The Time-Reversibility Paradox - Why Time Flows Both Ways

[@MedlifeCrisis]

I aspire to the energy on Boltzmann’s face when he thinks about unifying Newtonian laws 🙌

[@adityakhabiya5348]

Hey! I saw you on Tom Scott plus. You're amazing

[@nefariousyawn]

It's all in the beard.

[@kronologie]

5:30

[@vigilantcosmicpenguin8721]

Gotta say, that's not exactly the disposition I would want from a heart surgeon.

[@modemmark421]

*Confessions* *Of* *A* *Buddist* *Yogi:* Time and Space do not exist in "actual" reality, they exist only in a Human reality. The concepts of Time and Space are mutually complementary, i.e. they only exist commensurate with each other, or, they only exist as they imply each other. Kind of like Left and Right, or, Up and Down, you can't have a Left without implying a Right, or, Up only exist relative to your understanding of Down. "There is nothing good nor bad, but thinking makes is so" (Bill Shakespeare, as Hamlet). When you understand that a Left means nothing unless you infer a Right which defines and describes it, but neither exists alone, then you will see that "Time" is simply the Human way of defining and describing the duration of "Space" relative to an observer, but in "Actual" reality, there is only "Here" and "Now". The "Past" does not exist; the "past" only exists as a memory, but that memory is always being experienced, or happening in the Now. The "future" is nothing more an expectation of what may happen, but when that expectation is realized, it will be happening in the "Now". Get Real, *BE* *HERE* *NOW!*

[@Zeero3846]

This is the first I've even considered that every path from low entropy to high entropy has a corresponding path of high entropy to low entropy. I guess most others don't really go into much about the implications of that, so apparently, I've had a somewhat misleading understanding of the 2nd law of thermodynamics all this time.

[@honorarymancunian7433]

Right? So we're climbing out of the valley towards the heat death of the universe, but one day in the unimaginable far future we'll be climbing down into another valley of life once again? Big (bounce) if true

[@vigilantcosmicpenguin8721]

The universe is just a big Rubik's cube that keeps getting scrambled. It just seems highly unlikely that it'll ever get solved.

[@martifingers]

@@honorarymancunian7433 Isn't this akin to Sir |Roger Penrose's idea of Conformal cyclic cosmology?

[@stevenjones8575]

@@honorarymancunian7433 Yeah, but the expansion of the universe seems to undermine that argument. The classic entropy demonstration of gas molecules in a box doesn't really translate to cosmic scales unless there are some enigmatic walls that the expanding, accelerating spacetime of the universe can bounce off of.

[@mako9579]

Think of a lava lamp. That is CCC. Or at least I understand it that way. Or is it the Big Bounce? Help... My brain is rusty. 🤯

[@TheStubertos]

I went through 5 years at Engineering School not knowing what entropy really was, and you explained it to me in one KZbin video!

[@lorenfulghum2393]

I hope you aren't working on any critical infrastructure

[@thisguyy]

@@lorenfulghum2393 or or any everyday objects for that matter lmao

[@TheStubertos]

@@lorenfulghum2393 Nah just nuclear power stations lolz

[@YodaWhat]

It IS very confusing when they talk about Specific Entropy as just Entropy... source of a LOT of confusion when Engineers talk to Physicists.

[@naughtynedflanders434]

"Thermodynamics is a funny subject. The first time you go through it, you don't understand it at all. The second time you go through it, you think you understand it, except for one or two small points. The third time you go through it, you know you don't understand it, but by that time you are so used to it, it doesn't bother you any more. "

[@hallucinogender]

It strikes me that the graph you used with valleys representing temporally-local entropy minima could just as easily treat the entropy minimum at the big bang as just another dip in overall entropy. Could it just be that the universe never "started" at all, and the big bang is just the most recent in an infinite chain of entropy minima?

[@upandatom]

Watch my video on Boltzmann brains (or any video on it) to learn more about your questions :)

[@jorgepeterbarton]

Roger Penrose CCC theory? When all is at maximum state, there is no time as everything is photonic, the universe is a singularity in a sense and expands again into an infinitely larger universe that conforms to the last one in cycles...or something (i am not the best at explaining this, but a flat infinite equilibrium with no reference frames, may as well be a dimensionless point in conformal geometry and progresses to the high entropy state)

[@John-zz6fz]

Your point is good and seems inline with a pendulum-like state view of the Universe. Another way to look at that however is to revisit the old idea of big-crunch cosmology. We typically focused on gravity as the mechanism for cosmological reversal to a pre-big-bang state. Another option is that the big-crunch isn't induced by Relativistic physics but by QM effects. That is, if you consider the point just prior to the big bang to have a certain (very high) energy state then a ground state transition could occur that results in an emission, aka the big bang. That's a way oversimplified analogy to particle energy states but spontaneous emission is well established in QM so it's an easy if somewhat leaky analogy to start with. Obviously talking about cosmological scale QM isn't very natural with the typical formulation. If you think of extending the graph from the video over a cosmologic time scale with the big-bang on one end with the lowest entropy point and then assuming the universe were to evolve to a heat-death state, then the far end on the right could be a point of total thermal equilibrium. The pace of changes on the chart wouldn't be a constant, things are changing quickly in the beginning and then the dynamism of events essentially stops, or its at least moving as slow as possible at the other end. We can think of the flow of time as the rate of dynamism irrespective to a preferred direction. E.g. the pace that time flows is the rate of changes in the system relative to some minimum value (a cosmological tick, obviously ignoring Relativity). With lot's of changes, time is moving fast, with few changes relative to some fixed slowest process then time is moving slowly. In one sense time slows down to the point that spontaneous quantum events are the only remaining dynamics as kinematics are all in equilibrium. In that state even the extremely long timelines for electron and proton decay are now relevant. This is obviously beyond the area of what we understand and is now squarely in the field of speculation. Continuing to speculate and assuming the universe ends up with a state where particles have all spontaneously decayed into photon's or some other similar boson state then every particle in the universe is at complete thermal equilibrium and is entirely composed of bosons. That would put the entire universe into a Bose-Einstein condensate where most if not all of the Boson's are entangled. The comparison between the pre-big bang state and the heat-death state have some interesting questions. What is the difference in the total energy states from the beginning of the universe and the end? Meaning is the total energy of the systems in the two states the same? Conservation of energy would imply that the total energy in the two states should be the same. If the two states have the same total energy where is that energy bound? Say it's not the same, then we can assign the value |1> to the pre-big-bang state and |0> to the heat-death state. If all of the energy in the universe for either the beginning or the end is evenly distributed and all of the particle(s) are in the same energy level, is there a lower ground state? In the beginning we pre-supposed there was via our extremely leaky analogy. In the case of the universe as a Bose-Einstein condensate, if the universe is in equilibrium (temperature is zero) is there a lower ground state to transition into? If there is a lower energy state then what would happen to the entangled Bose-Einstein condensate if one of the Boson's were to decay to an even lower energy state? If the heat-death universe has no lower ground-state where did the energy get bound from the transition from |1> at the beginning to |0> at the end. If the energy at the end is bound somewhere else, can the heat-death universe in the Bose-Einstein condensate state transition to |1> via a QM absorption? I don't have any answers, just questions. My instinct on this is that the energy isn't really |1> or |0> but possibly some possibility like |1>,|0> and |0>,|1> or even more combinatoins. What I mean is in the pre-big-bang all of the energy is bound in one state and so the big-bang is a transition from the |1>,|0> towards the |0>,|1> state. The question on if the mechanism can reset itself is difficult obviously, though my bias is pulling me towards probably.

[@stevenjones8575]

@@upandatom Pardon my tangent, but the Boltzmann brain argument defeats itself: a hypothetical brain spawning randomly into existence is far, far more likely to spawn with an incorrect belief of the nature of the universe than to spawn with the correct one. By the boltzmann logic, we (as boltzmann believers) must therefore consider ourselves as almost certainly part of the incorrect class, and therefore rule out boltzmann brains.

[@jjhggdcqz]

@@upandatom How would a wormhole to the past work if time is an emergent property?

[@rayperkins6006]

The most accessible explanation of time and entropy I have yet come across. Well done.

[@sparky7915]

It is incredible that you can explain so many different and complex ideas so well!

[@larsnystrom6698]

@SPARKY If you can't explain it simply, you doesn't really understand it. I think R8chard Feynman said something like that. Anyway. If you can explain it comprehensively, then you know it. I guess that's why Jade do these videos!

[@rutomeds]

​@@larsnystrom6698 It's obvious though because any knowledagble person would know the way they understood the topic on the first place but a good teacher or explainer would try to use their methods of whatever they used to understand each topics to the listeners/students. This has been an intuitive process because the human mind works that way. But Feynman was surely the first person to popularise this concept. His learning techniques are still one of the greatest approach in underestanding anything.

[@markstracy5466]

Signing off with "I'll see you in the next episode" .... isn't it just as likely that you will see us in the previous episode? ;)

[@DonaldKronos]

Yep. Pretty much zero chance of either. Unless one of us is in a collab or something.

[@Buphumut]

Well, from your perspective, it may be an episode of the “past” but it is YOUR next episode. Her statement still stands.

[@nidadursunoglu6663]

But then the previous episode would be the next episode for you

[@StudlyStudmuffin]

That will be the next episode then.

[@RecklisBalla]

Hey hey hey heeey

[@truwth]

I've lately (or, futurely ?) been obsessed with time and entropy. This is a wonderfully clear overview. Great job.

[@hyperduality2838]

There is also a 4th law of thermodynamics, watch the spinning dancer:- kzbin.info/www/bejne/i5KraIt3fbR7r6c Bistability implies duality! Clockwise is dual to anti-clockwise. Left brain dominance is dual to right brain dominance. Master (Lordship) is dual to slave (Bondsman) -- the time dependent Hegelian dialectic. Brain dominance is visual proof of the Hegelian dialectic at work, problem, reaction, solution. The Hegelian (Fichte's) dialectic is dual if it is dependent & independent of time (both at the same time):- Thesis (action, problem) is dual to anti-thesis (reaction) creates the converging thesis or synthesis (solution) -- the time independent Hegelian dialectic. Action is dual to reaction -- Sir Isaac Newton (the duality of force or all forces are dual). Mind (the internal soul, syntropy) is dual to matter (the external soul, entropy) -- Descartes. Syntropy (prediction) is dual to increasing entropy -- the 4th law of thermodynamics! Teleological physics (syntropy) is dual to non teleological physics (entropy). "Always two there are" -- Yoda. Duality creates reality! The Necker cube is a good example of duality. From a converging, convex or syntropic perspective everything looks divergent, concave or entropic -- the 2nd law of thermodynamics! All observers have a syntropic perspective. Space is dual to time -- Einstein. Time symmetry is dual to time asymmetry -- time duality. Space symmetry is dual to space asymmetry -- space duality. Time duality is dual to space duality. Energy is dual to mass -- Einstein. Dark energy is dual to dark matter. The Big Bang is a Janus hole/point (two faces = duality) -- Julian Barbour physicist. Topological holes cannot be shrunk down to zero -- non null homotopic. Null Homotopic is dual to non null homotopic -- Duality.

[@10002One]

@@hyperduality2838 your comments, my anti-your comments. duel that!

[@rutomeds]

@@hyperduality2838 bruh

[@samanvayasrivastava559]

I am an arts grad and this scientific explanation of such a complicated matter was so easy to follow. This shows the brilliant work done by creator. I am subscribed ☺️.

[@nickmoore5105]

I have degrees in maths and engineering, and I find Jade’s videos is amazing too. She is able to choose and break down a topic, and communicate it so well for everyone without dumbing it down at all.

[@pasijutaulietuviuesas9174]

What I found missing is an explanation of why increasing entropy points the arrow of time. There's a correlation between the arrow of time and entropy increasing, but physicists often note that linking them together is a huge misconception and that correlation should not be confused with causation.

[@jasonlough6640]

I noticed that too. How does moving particles the other way cause time to go backwards? It shouldnt, unless Im missing something. Also, note that even in the graph showing increasing and decreasing entropy, the axis it happens on is the time axis, and always in the same direction. I think theres a conflating of ideas between direction of time and arrangement of particles. I also think that even if you were in a frame of reference going backwards in time, you would still perceive it as forward in time for yourself. On a slightly crazier note, dosent it seem like were going backwards through time? We see the past, but not the future, although the future is forward, therefore were walking backwards.

[@pasijutaulietuviuesas9174]

@@jasonlough6640 You're not missing something. Time does not go backwards inside your refrigerator despite entropy decreasing locally. The second law of thermodynamics is not broken because while entropy is decreasing inside the refrigerator, the refrigerator is not a closed system. The back of your refrigerator still ratiates heat into the environment and so entropy increases overall. But if entropy direction pointed time direction, the inside of your refrigerator should go backwards in time and it clearly doesn't. The point of the graph and the link between entropy and time direction is the idea that time should be symmetrical. If you cut out the beginning of the graph, it doesn't matter which way you point the time axis, the graph will look indistinguishable. The problem is that entropy increasing breaks time symmetry so because of entropy, time direction is distinguishable. But that's it. Entropy does not make time move forward, entropy only makes time direction distinguishable. That's why it's important not to fall into misconceptions. One solution to the problem shown by the video is that the big bang was the lowest point in entropy and that if you go back further in time, entropy increases backwards as well. It is possible that the universe started at the big bang but branched out into two opposite directions. 2nd law of thermodynamics is not broken before the big bang if the second branch of the universe ticks time in opposite direction. If we saw the dwellers of that branch of the universe, we would perceive them as moving back in time. But for those dwellers, time would move normally and they would perceive us as moving backwards in time. So yes, like you said, regardless of what arbitrary direction time moves, from our point of view, it moves forward.

[@JohnnyArtPavlou]

@@pasijutaulietuviuesas9174 Yes, but… Would we see people getting younger turning into babies and then into infants and then going back into the womb and then becoming an individual egg and an individual sperm cell? I mean I suppose if that’s how it occurred in our universe we were just accept it and find a way to explain it. And the other hand in the universe which was mirror “backwards“ time-Symmetrical to ours the mechanisms of life and death might operate in a completely different fashion.

[@pasijutaulietuviuesas9174]

@@JohnnyArtPavlou I can't imagine how the 'other' universe would form, so I can't say people would turn into babies and then go into wombs, but what we would observe is a trend towards all entropy decreasing and all matter and energy would trend towards a single point, towards the big bang, their time moving backwards. Whereas we see our universe in the opposite direction, trending away from the big bang and increasing entropy. But the dwellers of the 'other' universe would still see themselves as moving forward in time, they would actually see us going backwards in time. Now, obviously, "seeing" is a bit of a cheat because there would be no actual physical way to observe the other side of the universe. No information could pass between the two sides of the big bang. All we could know is that if such an opposite side of the universe would exist, it would exist reversed in our timeline. But just like different versions of the multiverse theory, this is just another version of speculative universes outside of our own.

[@pasijutaulietuviuesas9174]

@@micahmeneyerji You can. Because you have a direction of time yourself that you can compare to.

[@bonononchev634]

Your illustration of the ideas are great - I would also like to point out that when you are in a lower entropy state, essentially both ways increase it - and both ways are in fact "the future" for that person. I like Sean Carroll's explanation that it is not that entropy increases when time goes forward, but that "time going forward" and "entropy increasing" are the same statement - "entropy increase" is what our brain perceives as "time going forward". In a maximum entropy universe there will be no "time going forward".

[@mesplin3]

Speed of time = abs(d entropy / dt) ? ...? Idk. I don't know what t is.

[@notgary1111]

I always liked Dr. Carroll's explanation until I realized that it seems very unlikely we could have any awareness of the overall state of entropy in the universe. I'm beginning to wonder if the explanation of time's arrow has anything at all to do with entropy.

[@peterpike]

@@notgary1111 -- Time only matters to people who have the ability to think about time. Rocks don't care. Chemical reactions don't care. None of them understand "before" or "after". So, in that sense, time only exists as a construct of a mind that is capable of considering the difference between past and future. And since your memory is ALSO formed via physical processes, processes which if flipped would be undoing your memory, then you can only ever experience these processes in one direction. But secondly, your experience of time doesn't depend on your knowledge of the entire universe, just on your knowledge of what you are capable of perceiving at any given moment. The overall state of entropy in the universe doesn't matter to the person making observations, in other words. If I see an egg splattered on the floor suddenly put itself together inside a shell which then unbreaks, then I'm going to need to come up with an explanation for it. However, I strongly suspect that any part of the universe where a broken egg puts itself back together probably exists in the same state where an observer watching it happen is going to forget that the egg was ever broken "before" since whatever energy is needed to flip all of those physical forces is probably going to be flipping the physical forces recording memories too, such that the person who experience it in this framework is going to be "forgetting" instead of "remembering" things.

[@hyperduality2838]

There is also a 4th law of thermodynamics, watch the spinning dancer:- kzbin.info/www/bejne/i5KraIt3fbR7r6c Bistability implies duality! Clockwise is dual to anti-clockwise. Left brain dominance is dual to right brain dominance. Master (Lordship) is dual to slave (Bondsman) -- the time dependent Hegelian dialectic. Brain dominance is visual proof of the Hegelian dialectic at work, problem, reaction, solution. The Hegelian (Fichte's) dialectic is dual if it is dependent & independent of time (both at the same time):- Thesis (action, problem) is dual to anti-thesis (reaction) creates the converging thesis or synthesis (solution) -- the time independent Hegelian dialectic. Action is dual to reaction -- Sir Isaac Newton (the duality of force or all forces are dual). Mind (the internal soul, syntropy) is dual to matter (the external soul, entropy) -- Descartes. Syntropy (prediction) is dual to increasing entropy -- the 4th law of thermodynamics! Teleological physics (syntropy) is dual to non teleological physics (entropy). "Always two there are" -- Yoda. Duality creates reality! The Necker cube is a good example of duality. From a converging, convex or syntropic perspective everything looks divergent, concave or entropic -- the 2nd law of thermodynamics! All observers have a syntropic perspective. Space is dual to time -- Einstein. Time symmetry is dual to time asymmetry -- time duality. Space symmetry is dual to space asymmetry -- space duality. Time duality is dual to space duality. Energy is dual to mass -- Einstein. Dark energy is dual to dark matter. The Big Bang is a Janus hole/point (two faces = duality) -- Julian Barbour physicist. Topological holes cannot be shrunk down to zero -- non null homotopic. Null Homotopic is dual to non null homotopic -- Duality.

[@karenjeandiez6331]

@@peterpike yeah so its kind of the same with the conundrum "if a tree falls in the forest does it make a sound"? ...BTW this question was featured in this channel some time ago... which leads me to my point, something about the Copenhagen interpretation .. so is there a possiblity that because,us, humans, are able to measure time has made all the difference why we experience increase in entropy with time rather than the opposite? But, of course, were nonexistent during Bigbang so who was culprit? GOD? .. would want to hear your thoughts about these questions ...I dont even know if these questions are valid.... lol...

[@thecellulontriptometer4166]

I get the sense while watching this that Jade has the intelligence and teaching skills to work at any University as a lecturer. Makes me feel lucky she has decided to present science material on youtube.

[@pb6801]

The only problem is that she has fallen into a trap of just accepting some ideas such as the "big bang" as fact and is building a straw house on a foundation of shifting sand. Most scientists are now either rejecting the big bang or at least questioning the theory in response to the fact that the outer extents of our observable universe are accelerating away from us and are travelling faster than the speed of light. A common theory recently was the "big crunch" (it started a few decades ago and gained acceptance over time just like the big bang theory did before that), might I mention that the big crunch disregarded the laws of thermodynamics, and now is totally rejected by almost all scientists as just a weird idea that doesn't hold water.

[@marios1861]

@@pb6801 yes yes it's actually sky daddy. run along now.

[@MuffinMachine]

I just started reading “the three body problem” by Cixin Liu, and your opening section had some eerie parallels. Obviously this is because it illustrates some fundamental stuff about physics, of which I know nothing. But I do enjoy fantasizing about it artistically, which is why I also wanted to say I enjoyed your drawing of a well-landscaped graph of entropy. Thanks.

[@hyperduality2838]

There is also a 4th law of thermodynamics, watch the spinning dancer:- kzbin.info/www/bejne/i5KraIt3fbR7r6c Bistability implies duality! Clockwise is dual to anti-clockwise. Left brain dominance is dual to right brain dominance. Master (Lordship) is dual to slave (Bondsman) -- the time dependent Hegelian dialectic. Brain dominance is visual proof of the Hegelian dialectic at work, problem, reaction, solution. The Hegelian (Fichte's) dialectic is dual if it is dependent & independent of time (both at the same time):- Thesis (action, problem) is dual to anti-thesis (reaction) creates the converging thesis or synthesis (solution) -- the time independent Hegelian dialectic. Action is dual to reaction -- Sir Isaac Newton (the duality of force or all forces are dual). Mind (the internal soul, syntropy) is dual to matter (the external soul, entropy) -- Descartes. Syntropy (prediction) is dual to increasing entropy -- the 4th law of thermodynamics! Teleological physics (syntropy) is dual to non teleological physics (entropy). "Always two there are" -- Yoda. Duality creates reality! The Necker cube is a good example of duality. From a converging, convex or syntropic perspective everything looks divergent, concave or entropic -- the 2nd law of thermodynamics! All observers have a syntropic perspective. Space is dual to time -- Einstein. Time symmetry is dual to time asymmetry -- time duality. Space symmetry is dual to space asymmetry -- space duality. Time duality is dual to space duality. Energy is dual to mass -- Einstein. Dark energy is dual to dark matter. The Big Bang is a Janus hole/point (two faces = duality) -- Julian Barbour physicist. Topological holes cannot be shrunk down to zero -- non null homotopic. Null Homotopic is dual to non null homotopic -- Duality.

[@harperthejay]

Oh my goodness, I always love coming across new science youtube channels that I haven't seen before - I absolutely love the way you explain things, and I look forward to seeing more of your videos!

[@seanleith5312]

This woman is incredible: beauty never goes with intelligence, never. I see these two things in this woman. It's not supposed to happen. What is going on?

[@harperthejay]

@@seanleith5312 I don't know what you think you were doing here, or if you thought I was going to agree with you ,but this comment is disgusting and reeks of misogyny. Don't say shit like this.

[@l1mbo69]

@@harperthejay misogyny is hatred against women in general Beauty and intelligence not going together first of all has little to with women in particular, it can be applied to men just by changing beauty to handsomeness. Even that shouldn't be strictly needed but its unusual to use beauty in the context of males. Secondly, it's clearly not saying that women are on avg less or more intelligent or anything like that, just that for any one individual it's either of the two. So the statement is really just an expression of a statistical truth, assuming a high enough barrier for what we consider beautiful and intelligent, say the upper 1/10th of the entire population for each trait. Then, the probability for someone to be in top 1/10 for both would be 1/100. Ofcourse it's not really never, but that was just hyperbole If you're wondering why i even bothered wasting my good 3-5 mins writing this comment, its because I'm tired of people labelling everything misogynistic without actually giving any thought to if that even makes sense

[@TimJBucci]

@@seanleith5312 There are many forms of intelligence and beauty, and about as many ways to find those in a woman if you're actually looking for them.

[@seanleith5312]

@@TimJBucci I am aware of that. I just don't see beauty and intelligence that often. Do you?

[@willardroad]

8 AM..... 8 PM..... same outfit.... as a video editor, I was delighted to see the efficiency of looping the first bit with exposure and saturation dialed down. Nice! And I am loving these videos - kinda binge-watching tbh. Thanks for making them.

[@Lucky10279]

7:36 The better way to say it is, "The entropy of a closed/isolated system tends to a maximum". i.e. Given sufficient time, any system that has no energy entering or leaving it will eventually end up in the most probable macrostate, where a macrostate is just a description of the system in macroscopic terms. That's most certainly a _statistical_ law -- it's essentially just an application of the law of large numbers, but, in my view, that actually makes it cooler.

[@anywallsocket]

the law of large numbers is itself just the fact that an infinite number of random variables between let's say -1 and 1 must have its mean equivalent to the range's mean = 0. This is the definition of the simplest possible random variable.

[@Lucky10279]

@@anywallsocket I've never heard ot described like that. I've already heard it described along the lines of "as the number of trials of some experiment approaches infinity, the proportions of each outcome will approach the theoretical probabilities." e.g. If you roll only a few times, it wouldn't be that weird to get, say a 3 each time. But if you keep rolling the die more and more times, the proportion of times each number is rolled should get closer and closer to 1/6. Hmm. Now that I've typed that out, I realize that actually is very similar to how random variables are usually defined. It's been a bit since I've actually used the term "random variable". I'm a stats tutor, hence my familiarity with probability, but I can't remember the last time a student asked me about random variables. Lots of people ask me about the basics of what probability is though.

[@jimmyr545]

One of the most fascinating videos I've ever seen. Eye opening that entropy could go either way and it only increases because we started at low entropy and who knows why. And that time is an emergent property. And loved the explanation of entropy as equilibrium instead of disorder.

[@Zuzezno]

Actually, the video stated that time having a direction is an emergen property, not time itself. I'm not saying that time isn't an emergent property, but this wasn't what the video was about.

[@jimmyr545]

@@Zuzezno yes you're right about that. Thanks for pointing it out.

[@maxsamarin9002]

I love this! Finally a proper explanation. The popular explanation for the direction of time due to "at the next time step, the system is more likely to evolve into a more disordered state" never sat well with me, because in this phrase the word "next time step" already has the future arrow of time baked into it. Same should be true for the "previous time step". This video addresses that problem very nicely! In the example of particles in a box, if the particles start off in a highly ordered state in the corner of the box, it is there only because we humas set it up that way and used energy to do so. Naturally, entropy increases in both directions of time - if we look at the film of particles in a box backwards, they will eventually bundle back into the corner, but after that, bounce back to the high-disorder states all around the box. The reason why we don't see that happen backwards in time, is because in the moment when particles come back to the corner, there will be a human hand to interrupt the whole process of entropy increasing backwards in time (because a human hand placed those particles there :D ). So all apparent directions of time simple stem from the mysterious low-energy state of the universe in the beginning. How cool is that? We psychologically experience the flow of time, remember the past but don't know the future, stems from a much larger picture that universe as a whole is tending towards an equilibrium on a scale of billions of years. Indeed, the question remains, why was the universe in such a low-entropy state in the beginning? Maybe this doesn't even need a special reason- like was pointed out in the video, given astronomical amounts of time, dips of entropy can get very big, so maybe the same was for the big bang. So all good there! However, one final question remains to me: why is there a cosmological arrow of time (the expansion of the universe only in one direction)?

[@sebastianwittmeier1274]

If the future would have lower entropy instead, we would call it the past. The definition of a low-entropy state (=grouping of microstates) is arbitrary. Every state is special. Quantum mechanics time evolution is reversible. Quantum computers are computers, where the state does not change entropy during the computation. There is no reason, why the past (or the time with lower entropy) should be 'more' fixed than the future (time with higher entropy). The people making probabilistic arguments about the past, and saying that a low-entropy state is so improbable (if a state is chosen at random) are basically (if one applies their thinking) also saying that it is 1:(10^high power) more likely that all humans are manipulated than that our research and logic and rememberance of our past and experience of the present or any deduction of physics law or mathematics is true. So it is an argument, which denies its own logic.

[@GraemePayne1967Marine]

Finally --- a description of entropy that I can actually understand. Thank you.

[@doloreslehmann8628]

So glad I found your channel today. It's absolutely amazing how you manage to explain those complicated topics in such an easily understandable way! Subscribed!

[@gangsterdaddy510]

That is the best explanation of entropy i've ever heard. it really helped me understand it better

[@CstylesX]

I'm new to your channel, but it's good to see you posting videos again! Keep up the great work, and thanks for the interesting videos!

[@upandatom]

Welcome!!!!!

[@leif1075]

@@upandatom Hey Jade. I hope you can respond to my question about quantum entanglement when you can. Thanks very much .

[@AquarianSoulTimeTraveler]

@@upandatom @Up and Atom you are such a living walking piece of garbage I can't believe you just took this video and spun it into anti Big bang propaganda BS! One of the biggest problems with third dimensional existence is the fact that we think that whatever we can see we can measure accurately... This is completely untrue! If we sent out a enormous amount of spaceships that we could actually accurately track the distance in which they have traveled from this Earth and we mapped our entire galaxy it would be nothing but a tiny little speck compared to the entire universe of everything we can see. Accelerating expansion of the universe pass the speed of light and constantly picking up speed is an illusion caused by dark matter... Contrary to popular belief dark matter does interfere with regular matter. I think it's pretty audacious of the scientific community to say that dark matter has no interaction with regular matter when they haven't even identified what dark matter is comprised of and have never even found a dark matter particle!!! Everything bust forth from the singularity the problem is science wants to move itself away from the singularity because it realizes that the singularity is "God". Ultimately everything is one. Dark matter is the counter action force to the expansion of the universe... Let's say that dark matter is comprised of hooks instead of strings. This is the reason why we cannot view a dark matter particle and I've never found one because we are composed of strings these hooks can rip off tiny fractions of those strings of all material that pass through it and convert it into hooks. Light has mass this is the reason why I like cannot escape a black hole it is mass in motion when it comes to a resting point it no longer contains mass and it no longer exists. Light sheds its mass to maintain its velocity just like everything else. The reason why light cannot escape a black hole is because guess what it contains Mass anything that contains volume contains Mass... You cannot give something volume without giving it Mass! If you take a two-dimensional plane and you put it in any direction in any position near a black hole wherever you want to put it it will have absolutely zero interaction with a black hole! Do you know why because guess what in the second dimension there is absolutely no mass and therefore black hole cannot have any interaction with that two-dimensional plane! I'm not disagreeing with you on the fact that time can reverse and roll backwards but to think that anything ever started from anything other than a singularity is just insanity! This anti Big bang mindset is totally insane! Also this accelerating expansion of the universe pass the speed of light mindset is equally insane! And I completely understand what the idiot say about how since it is expanding into nothing it can pick up speed past the speed of light but that's just total garbage! Dark matter is absorbing bits and pieces of all energy that pass through it it is surrounding our entire solar system our entire galaxy and is constantly growing by absorbing bits and pieces of energy that pass through it ripping off strings fractions of a penny of mass and slowly increasing it's density... This is happening equally as this does happen and dark matter increases its density it creates an illusion of accelerating expansion of the universe past the speed of light! It is far more logical and far more reasonable to say this than to say any of the BS that people spout about anti Big bang! Sorry but I just couldn't let you get away with it especially when you leave it on a cliffhanger like that and obviously really don't know anything... There's a reason why your video got pushed to me by the KZbin algorithm because it's nothing but BS propaganda anti Big bang anti-singularity anti-god BS crap! Then again none of us are immortal beings that have existed from the very beginning of time and will exist to the very end of time so none of us can experience real objective truth and objective truth does not exist here in the third dimension... So guess what I'm wrong and you are wrong and every single person here will be wrong and it is completely pointless to even try to figure anything out because guess what they will be wrong too!!!!!

[@alvgadea]

You've got some of the best production quality. The music in your videos is so good that I often get distracted just listening to it and stop paying attention to your explanations haha. Thanks for another great video!

[@thesearesystems2003]

Fantastic video, and a great explanation! I'd love to mention one more detail distinguishing the past from the future: the past is the only time direction that we can form memories of! That's why, while a universal entropy gradient defines an arrow of time, one of those directions feels distinctly to us like "the past" and the other like "the future". (Of course, then we wonder why it is that we can only store memories of states behind us along the universe's entropy gradient, rather than those ahead of us, and then we end up at the fascinating thermodynamics of computation and memory).

[@davidpetersonharvey]

Consider that the state of particles and energy in your mind also follows these laws, so you do not experience the reversal because your makeup and memories are part of the system.

[@thesearesystems2003]

@@davidpetersonharvey Precisely!

[@twinsoultarot473]

If we are already being visited by "us" in the future. These "us" beings with human like qualities have achieved this coveted state of equilibrium to be able to traverse the sea of time in both directions. They can go either way.

[@mimigoodcat4950]

You are observing your thought process time is psychic.

[@ianoliver3130]

@@davidpetersonharvey true! If you reversed the speed of every snooker ball exactly soon after the initial break, they would not return to to form a triangle and push the white out back along the table. Because some energy has been lost as sound making air molecules, your eardrum and cells in your brain vibrate forming a memory.for time to reverse you would have to lose that memory in a exact reverse procedure

[@Dudleymiddleton]

Good on you, Jade as usual - So well explained, such an extremely difficult skill to put it into layman's terms. Well done! :)

[@phillippearson7740]

Thank you for that explanation. My students are learning Thermochemistry right now and I might be able to explain delta S a little differently now. Your graph helped to visualize the concept well, and it made me think. What if the big bang isn't a beginning, but only one of the extreme dips in the graph. There could have been a state of equilibrium before it, but with a state of such low entropy, then there was a violent rush toward high entropy.

[@GradyPhilpott]

That sounds like a bounce.

[@zbzbzbzbzb3288]

How do we know if it's extreme at all?

[@undercoveragent9889]

How did your students cope with the revelation that a system in equilibrium can spontaneously fall out of equilibrium?

[@josemanueld5413]

Love how well you approached and gave rich insight on such a complex issue in so brief lapse of time!

[@binbots]

The arrow of time points forward in time because of the wave function collapse. Because causality has a speed limit every point in space sees itself as the closest to the present moment. When we look out into the universe, we see the past which is made of particles. When we try to look at smaller and smaller sizes and distances, we are actually looking closer and closer to the present moment. The wave property of particles appears when we start looking into the future of that particle. It is a probability wave because the future is probabilistic. Wave function collapse happens when we bring a particle into the present/past.

[@THeMin1000]

Goddamn! 😲 This is an intersting interpretation. Is there any book that discusses this in detail with the math included?

[@binbots]

@@THeMin1000 I came up with it about a year ago. But apperantly Lee Smolin wrote a paper about it last year that seems to say the same thing.

[@TheDanEdwards]

" The wave property of particles appears when we start looking into the future of that particle." - if that were true then we'd never have experiments which demonstrate wave properties. By definition, when we look at empirical results we are look at what happened in the past, and pleny of experiments demonstrate wave properties. " It is a probability wave because the future is probabilistic. " - a wave function of a particle is not a "probability wave". It does turn out that we interpret Ψ*Ψ as a probability, but Ψ itself is not.

[@jorgemachado5317]

Could be a good idea for a video: What is probability? Probability is just a concept? If it is how it describes the universe? Probability could be a law of nature? Probability could be a fundamental force? What does it mean to be probable?

[@lvmbk3755]

It's probably the 5th dimension Did I answer in terms of probability to a question about probability? 🤔

[@ZelphTheWebmancer]

@@lvmbk3755 Probably

[@mesplin3]

the price at which one would buy or sell a bet that pays 1 unit of utility if event E occurs and pays 0 units of utility if event E doesn't occur.

[@VictorSiberian]

She makes a good teacher of physics, doesn't she. I lacked this illustrative approach back in the days when at school. Kudos!

[@seangilbreath7378]

You explained entropy very well and I actually understand it a ton more from this. Thanks!

[@elminster8149]

I don't know how long you spent on this Jade, but this is one of the best videos I've seen for a while and explains it really clearly. Time well spent!

[@narfharder]

Forward time primarily, amirite?

[@upandatom]

Thanks I spent 3 months on it :)

[@aniketmore8236]

@@upandatom omg 3 months But it's worth it

[@vigilantcosmicpenguin8721]

@@upandatom So it'd take three months in the other direction to destroy this video.

[@proloycodes]

@@vigilantcosmicpenguin8721 lmao

[@monkeycigs4762]

"Is time going backwards in my refrigerator?" That blew my mind and made me laugh out loud. Well done!!

[@CaioKauffmann]

Dear Jade this was so beautifully put together! Thank you for producing great content!

[@MitchJ]

Hi Jade! Thanks for another great video. You always explain things so well, and they're always interesting physics concepts.

[@KarlDeux]

And so catchy!

[@upandatom]

Thank YOU for watching :)))

[@hyperduality2838]

There is also a 4th law of thermodynamics, watch the spinning dancer:- kzbin.info/www/bejne/i5KraIt3fbR7r6c Bistability implies duality! Clockwise is dual to anti-clockwise. Left brain dominance is dual to right brain dominance. Master (Lordship) is dual to slave (Bondsman) -- the time dependent Hegelian dialectic. Brain dominance is visual proof of the Hegelian dialectic at work, problem, reaction, solution. The Hegelian (Fichte's) dialectic is dual if it is dependent & independent of time (both at the same time):- Thesis (action, problem) is dual to anti-thesis (reaction) creates the converging thesis or synthesis (solution) -- the time independent Hegelian dialectic. Action is dual to reaction -- Sir Isaac Newton (the duality of force or all forces are dual). Mind (the internal soul, syntropy) is dual to matter (the external soul, entropy) -- Descartes. Syntropy (prediction) is dual to increasing entropy -- the 4th law of thermodynamics! Teleological physics (syntropy) is dual to non teleological physics (entropy). "Always two there are" -- Yoda. Duality creates reality! The Necker cube is a good example of duality. From a converging, convex or syntropic perspective everything looks divergent, concave or entropic -- the 2nd law of thermodynamics! All observers have a syntropic perspective. Space is dual to time -- Einstein. Time symmetry is dual to time asymmetry -- time duality. Space symmetry is dual to space asymmetry -- space duality. Time duality is dual to space duality. Energy is dual to mass -- Einstein. Dark energy is dual to dark matter. The Big Bang is a Janus hole/point (two faces = duality) -- Julian Barbour physicist. Topological holes cannot be shrunk down to zero -- non null homotopic. Null Homotopic is dual to non null homotopic -- Duality.

[@AquarianSoulTimeTraveler]

@@upandatom @Up and Atom you are such a living walking piece of garbage I can't believe you just took this video and spun it into anti Big bang propaganda BS! One of the biggest problems with third dimensional existence is the fact that we think that whatever we can see we can measure accurately... This is completely untrue! If we sent out a enormous amount of spaceships that we could actually accurately track the distance in which they have traveled from this Earth and we mapped our entire galaxy it would be nothing but a tiny little speck compared to the entire universe of everything we can see. Accelerating expansion of the universe pass the speed of light and constantly picking up speed is an illusion caused by dark matter... Contrary to popular belief dark matter does interfere with regular matter. I think it's pretty audacious of the scientific community to say that dark matter has no interaction with regular matter when they haven't even identified what dark matter is comprised of and have never even found a dark matter particle!!! Everything bust forth from the singularity the problem is science wants to move itself away from the singularity because it realizes that the singularity is "God". Ultimately everything is one. Dark matter is the counter action force to the expansion of the universe... Let's say that dark matter is comprised of hooks instead of strings. This is the reason why we cannot view a dark matter particle and I've never found one because we are composed of strings these hooks can rip off tiny fractions of those strings of all material that pass through it and convert it into hooks. Light has mass this is the reason why I like cannot escape a black hole it is mass in motion when it comes to a resting point it no longer contains mass and it no longer exists. Light sheds its mass to maintain its velocity just like everything else. The reason why light cannot escape a black hole is because guess what it contains Mass anything that contains volume contains Mass... You cannot give something volume without giving it Mass! If you take a two-dimensional plane and you put it in any direction in any position near a black hole wherever you want to put it it will have absolutely zero interaction with a black hole! Do you know why because guess what in the second dimension there is absolutely no mass and therefore black hole cannot have any interaction with that two-dimensional plane! I'm not disagreeing with you on the fact that time can reverse and roll backwards but to think that anything ever started from anything other than a singularity is just insanity! This anti Big bang mindset is totally insane! Also this accelerating expansion of the universe pass the speed of light mindset is equally insane! And I completely understand what the idiot say about how since it is expanding into nothing it can pick up speed past the speed of light but that's just total garbage! Dark matter is absorbing bits and pieces of all energy that pass through it it is surrounding our entire solar system our entire galaxy and is constantly growing by absorbing bits and pieces of energy that pass through it ripping off strings fractions of a penny of mass and slowly increasing it's density... This is happening equally as this does happen and dark matter increases its density it creates an illusion of accelerating expansion of the universe past the speed of light! It is far more logical and far more reasonable to say this than to say any of the BS that people spout about anti Big bang! Sorry but I just couldn't let you get away with it especially when you leave it on a cliffhanger like that and obviously really don't know anything... There's a reason why your video got pushed to me by the KZbin algorithm because it's nothing but BS propaganda anti Big bang anti-singularity anti-god BS crap! Then again none of us are immortal beings that have existed from the very beginning of time and will exist to the very end of time so none of us can experience real objective truth and objective truth does not exist here in the third dimension... So guess what I'm wrong and you are wrong and every single person here will be wrong and it is completely pointless to even try to figure anything out because guess what they will be wrong too!!!

[@TurnerRentz]

This sharply done video covers alot, in a very small amount of time. Well worth the watch. Wonderful job.

[@elminster8149]

If we ask "Why did the universe start in such a low entropy state with the big-bang, if this is highly improbable?", then shouldn't we be asking if the big bang was the start of the universe? After all, it may have just been a dip in entropy.

[@anywallsocket]

indeed. perhaps the global entropy of the greater universe is like the Weierstrass function, always increasing or decreasing, depending on your level of zoom.

[@Vastin]

Bear in mind that when you say 'a dip in entropy' on that scale, you are describing time running backwards for our entire universe for its entire 15-odd billion year lifespan so precisely that every single particle in it just happen to all end up at a single point in spacetime. I think you could safely argue that it's almost infinitely more likely for countless universes to simply pop out of the vacuum state by pure chance than for an existing one to 'reset' itself by chance in this manner - unless we can posit a more realistic mechanism for it to do so.

[@Vastin]

Think about what it would look like to live in a universe during such a period of statistically unlikely anti-entropy. The rules of physics and math would be no different from ours, and their derivations would tell them that entropy should increase - but against all possible chance, nothing would behave as it should. That world would seem utterly magical, with vases unbreaking, animals undying, people being unborn - not because the laws of physics say it should happen, but because pure chance must generate such thermodynanically unlikely miracles one after another for BILLIONS OF YEARS on end to get back to that ultra low entropy state. In our universe any one of these events would be so unlikely as to have almost no realistic probability of happening even once before every star in our universe undergoes complete baryon decay.

[@anywallsocket]

@@Vastin your understanding is weak but your imagination is strong

[@Vastin]

@@anywallsocket Well, go ahead and describe an extended period of steadily reducing entropy in our universe then. I'm all ears.

[@NullPointerException7]

This is my favorite video of yours to date! Such a fascinating concept and you explained this so well.

[@hyperduality2838]

There is also a 4th law of thermodynamics, watch the spinning dancer:- kzbin.info/www/bejne/i5KraIt3fbR7r6c Bistability implies duality! Clockwise is dual to anti-clockwise. Left brain dominance is dual to right brain dominance. Master (Lordship) is dual to slave (Bondsman) -- the time dependent Hegelian dialectic. Brain dominance is visual proof of the Hegelian dialectic at work, problem, reaction, solution. The Hegelian (Fichte's) dialectic is dual if it is dependent & independent of time (both at the same time):- Thesis (action, problem) is dual to anti-thesis (reaction) creates the converging thesis or synthesis (solution) -- the time independent Hegelian dialectic. Action is dual to reaction -- Sir Isaac Newton (the duality of force or all forces are dual). Mind (the internal soul, syntropy) is dual to matter (the external soul, entropy) -- Descartes. Syntropy (prediction) is dual to increasing entropy -- the 4th law of thermodynamics! Teleological physics (syntropy) is dual to non teleological physics (entropy). "Always two there are" -- Yoda. Duality creates reality! The Necker cube is a good example of duality. From a converging, convex or syntropic perspective everything looks divergent, concave or entropic -- the 2nd law of thermodynamics! All observers have a syntropic perspective. Space is dual to time -- Einstein. Time symmetry is dual to time asymmetry -- time duality. Space symmetry is dual to space asymmetry -- space duality. Time duality is dual to space duality. Energy is dual to mass -- Einstein. Dark energy is dual to dark matter. The Big Bang is a Janus hole/point (two faces = duality) -- Julian Barbour physicist. Topological holes cannot be shrunk down to zero -- non null homotopic. Null Homotopic is dual to non null homotopic -- Duality.

[@YvanCartwright]

Very enlightening and gave me a more thorough insight into the concept of entropy than I had before. +1 subscriber!

[@doopox]

This is one of the best explanations of the concept of entropy I have ever seen. Given the fact that it was done in about 15 minutes. Rising some new questions in my head. Is the time determined only by the state of elementary particles? If we somehow arranged particles in the way they were in the past, would that mean that we moved back in time?...

[@kenten]

Okay, that's a fascinating idea. If a hypothetical being from the Q continuum rearranged all particles to a previous state, say, one year ago, including all photons, unfusing nucleii in stars, pulling all absorbed photons out of particles and sending all emitted photons back into particles, resetting all particles positions and every states, which resets all chemistry including resetting all brains back to previous configurations (meaning most recent stored memories are from one year ago), technically the universe would be in March 2022 but in the state of March 2021. So is that in any way distinguishable from the ACTUAL 2021, or is the process of rearranging the particles indistinguishable from actual time travel? Though the rearranging would probably have to be universe-wide at the same time, right? Otherwise if the Q being went planet by planet or galaxy by galaxy, new light from Star A would fall on the Planet B while Planet B is being rearranged, and now rearranging Star A means having more undo-work to do on affected Planet B, so Q would be stuck in a never-ending task running around and re-tweaking things that keep affecting each other. Anyway, fascinating.

[@doopox]

@@kenten wow, nice answer. It's like something impossible from our perspective. From that Q being's perspective, it can be something like resetting the computer game to some previous state (every bit in that computer's memory). Or what if we have done it more locally, on macroscopic scale? Let's say that you live in a cave and never go out. You have few things in there (bed, cup, watch...). You go to sleep and I enter the cave, arrange everything in the cave the way it was let's say two days ago. An I leave. You wake up and probably would feel like some time traveller who travelled two days backward in time (keeping your memories and also aging normally)

[@anywallsocket]

All particles of mass have a corresponding wave-length, and so act like clocks - which are themselves irreversible. Indeed, it's thought that even elementary particle will all eventually decay. To understand this consider the fact that no matter how efficient you think your 're-arranging', it will never be 100% efficient, and therefore you will waste heat trying to fix things, and more heat trying to fix the heat you wasted, etc., like trying to sweep the last bit of dust into the dustpan -- it's impossible.

[@tedwalford7615]

@@kenten WE would never know that that had happened!

[@vigilantcosmicpenguin8721]

@@kenten Dude, if there are any hard sci-fi authors reading this, this HAS to be the premise for a time travel story.

[@kevin7410]

This was FANTASTIC! It's so satisfying to see such interesting concepts explained so well and so concisely. What you covered in this video used to take years of study. Time may not exist, but the future is now :D

[@hyperduality2838]

There is also a 4th law of thermodynamics, watch the spinning dancer:- kzbin.info/www/bejne/i5KraIt3fbR7r6c Bistability implies duality! Clockwise is dual to anti-clockwise. Left brain dominance is dual to right brain dominance. Master (Lordship) is dual to slave (Bondsman) -- the time dependent Hegelian dialectic. Brain dominance is visual proof of the Hegelian dialectic at work, problem, reaction, solution. The Hegelian (Fichte's) dialectic is dual if it is dependent & independent of time (both at the same time):- Thesis (action, problem) is dual to anti-thesis (reaction) creates the converging thesis or synthesis (solution) -- the time independent Hegelian dialectic. Action is dual to reaction -- Sir Isaac Newton (the duality of force or all forces are dual). Mind (the internal soul, syntropy) is dual to matter (the external soul, entropy) -- Descartes. Syntropy (prediction) is dual to increasing entropy -- the 4th law of thermodynamics! Teleological physics (syntropy) is dual to non teleological physics (entropy). "Always two there are" -- Yoda. Duality creates reality! The Necker cube is a good example of duality. From a converging, convex or syntropic perspective everything looks divergent, concave or entropic -- the 2nd law of thermodynamics! All observers have a syntropic perspective. Space is dual to time -- Einstein. Time symmetry is dual to time asymmetry -- time duality. Space symmetry is dual to space asymmetry -- space duality. Time duality is dual to space duality. Energy is dual to mass -- Einstein. Dark energy is dual to dark matter. The Big Bang is a Janus hole/point (two faces = duality) -- Julian Barbour physicist. Topological holes cannot be shrunk down to zero -- non null homotopic. Null Homotopic is dual to non null homotopic -- Duality.

[@gabrieltomaz6034]

“Time may not exist” Does anyone knows a way to prove it does exist? Because it doesn’t seam necessary indeed I can say “I’ll arrive in 24h” It only means Earth is gonna round around itself once It’s actually space based

[@RF-fi2pt]

@@gabrieltomaz6034 Time existe! Movement is a changing of states. Your "Earth round itself once" is measured in other axis which register that space changed states: time axis. dx=v.dt. Like the videos of thesseract, using one (unproved) Space time of 5 dimensions, where the 4d space object change states measured at more one time dimension.

[@mervinlitzenberger4779]

@@gabrieltomaz6034 I also cannot justify the existence of time. It is a useful calculation of kinetic energy's effect on a mass.

[@RF-fi2pt]

@@micahmeneyerji hours definition are exact by a multiple of the exact definition of second by the ceasium 133 Atom transition. But to be coherent with rotation of Earth the difference in seconds from 24 is counted and in some point adjusted, as the yearly translation time is adjusted every 4 years. So the reference hours institutions know at each instant the difference to a perfect 24h day and perfect 365 days year.

[@mrclint7377]

Without having watched any other videos it feels like time does not reverse but slows down with low entropy. Like when the universe were born.

[@minimike1995]

I feel like I'm missing something here. To me, the time-reversibility paradox comes from the assumption that consequences are the same forward and backward in time. Take 2 particles travelling at each other at 10ms-1. These particles would collide and deflect, but would lose some energy through sound or heat, leaving 2 particles with less combined energy between them. Going backwards the 2 particles would have to gain energy to return to their full 10ms-1 each. Would they not lose more?

[@jayquirk2297]

Just figuring this out myself, but does the heat/energy not reverse as well? If you added energy to the particles at the time of collision, they could leave at a faster rate than they arrived. Jade's ball example is very similar. In forward time, energy was released to propel the ball and then energy was absorbed when caught. In reverse time, the energy that had been absorbed is now released to throw the ball in reverse time.

[@Iffy50]

Great thought. I think that the video was a simplification of the theory. I think the point is that for any position of the particles, there exists a set of velocity vectors that will bring them all back together into a lattice. (the initial conditions change depending upon what factors you are considering (heat/sound/gravity/drag), but there is always a solution set that will work, actually there are probably an infinite number of solution sets) Anyway, I don't know why that would make me believe that time can go backwards.

[@maximejanuel8118]

It doesn't make sense. Particle can't lose heat energy 'caus it is the particle themselves who posses heat in bigger system. colliding particle lead to two thing : if their velocity is hight enough they'll merge into bigger particle by losing neutrino and other particle OR have an elastic shock. in both way it's possible that things can happen in reverse but quasi improbable. Due to the stable statesment of the universe that everything tend to have lower energy. The universe can't gain or lose energy he is stable finite with finite energy.

[@eugenkeller]

Not sure it's relevant but... I'm really astonished that people discuss time reversibility. Forwards or backwards, the particles will always lose energy by colliding. Reversibility does not work with time (only time invariance, different topic). Everything flows in one direction, with time. I would say, the basis for this is causality. Describing colliding backwards in time is a nice one. Time reversibility is a childish star trek myth. This is what entropy is about, what second law of thermodynamics is about and what time is about. AND: what causality is about, you cannot reverse CAUSE and EFFECT. First cause, after some TIME, we have the effect. Also existence and energy preservation is dependant on time. Also, there are no time wormholes, this is nonsense, only space wormholes. No going back in time, and no "faster than light" speed of particles. This all should flow from the current physics. Or am I missing something?

[@galenburnett9791]

@@eugenkeller that’s what i think too

[@raman_14264]

This video was really awesome Jade. Well Done It cleared my doubts related to time and entropy. Even can you make your new video on Fermi Paradox

[@upandatom]

Thank you! Hmm I don’t know there are already so many great videos about fermi’s paradox!

[@autohmae]

@@upandatom well, not enough include the The Lucky/Rare Earth Hypothesis. And if we are so unique maybe we should really be taking better care of our environment (I initially wrote planet, but the planet will be fine). But also important to point out: the more conditions we add to the Rare Earth Equation, the more we limit our view to 'life like our own' instead of life in general. Something else to consider: are you trying to educate your audience (your current subscribers) or are you trying to grow your audience ? Because if it's the first then it doesn't matter if other videos already exists just the probability of them having already seen it

[@curtissmith6507]

whether you are going from high to low or low to high you will always go that way because there is nothing which can bounce time and make it change directions.

[@luudest]

The arrow of time is associated with entropy. What is associated with time as a quantity? Why is a second always a second?

[@Cythil]

Well... A second is not always a second to being with. That is what that fellow Einstein figured out. Though, this is a dumb way to dodge your question. Since whole length of time can contract and lengthen, there is still an idea of a length of time. If all things are being equal, a second is as long here as any other place. Relative to where I am, a second is always a second. It does not speed up or slow down locally. I am not sure if I am equipped to explain why this is. But I will try. And I will bring it back to those symmetries mentioned before. The quantiles of the system is preserved. That includes the motions. So even if something would start to change faster, you would have to trade it off with something else. Preserving the whole symmetry of the system. Again, I am not sure if this helps at all to explain it. Edit: Try to think of it like you did not have time at all in your model of the universe. Just states that changes continuous, but is always in symmetric.

[@franciscofernandez8183]

Same as space, what defines the amount is what can happen/be in between.

[@Vastin]

Well - it isn't? Thanks to relativity, a second gets shorter when you go into orbit, and it gets longer when you hang out too close to a black hole. In terms of perception, time can also vary significantly. Many species perceive time at different rates. A bird that evolves to fly through dense forests at high speeds should perceive the world at a significantly different 'frame rate' than we do, simplifying their view of the world but also slowing it down so they can make decisions fast enough to not go splat. Even a pro-sports-ball player most likely sees the world at a very slightly slower rate than does the average person, and there are a few drugs that can more dramatically change your perception of time (and other things...) As for the objective measurement of time, I think the core value there is Plank Time, which is the theoretical shortest amount of time over which any change at all can happen - but even plank time is affected by relativity, so there is no perfectly fixed unit of time.

[@davidh.4649]

I don't always fully understand the concepts you try to explain to us in your videos Jade (despite having degrees in Physics and Engineering) but I always look forward to them. You and Physics Girl are the best at explaining complex ideas in a way that gives us the best chance to understand them. Good video as always! 😊 Oh, and some good ball skills there! 😁

[@andybaldman]

Physics girl is way more fuckable.

[@deer001]

OMG,you made my day. Whenever I watch a video and don't understand something, I feel like a dumbass😂 Sometimes I try to make myself understand that I'm only in 12th grade,It's okay if i don't understand something of higher level... Now knowing that others also don't understand something despite having degrees, made me feel good😂😂

[@davidlafleche1142]

Time does not flow backwards. Time travel is impossible. God shall never permit it.

[@galenburnett9791]

you would like to see her ball skills i think?

[@KW-12]

Got my like when you mentioned that entropy isn't disorder. The definitivo you gave is mucho better. I also like to think of entropy as a measure of irreversebility in an isolated system. Almost every physics theory assumes that the system is isentropic for a good reason (and also isolated)

[@muhammadismaeel8759]

Constantly waiting for two weeks to listen you explaining these fascinating concepts ❣❣ Finally it's here🤩🤩🤩

[@alisherghumman2810]

Me toooo ❣️

[@airfiregamer4550]

Time is really a fascinating creature

[@AliSher-ik8uu]

Ah! Me too anxiously waiting for the video

[@stephenpuryear]

Jade this is another superb video. I am so glad to see that you are surviving the adventures that the world happens to be going through. Please keep it up!

[@hyperduality2838]

There is also a 4th law of thermodynamics, watch the spinning dancer:- kzbin.info/www/bejne/i5KraIt3fbR7r6c Bistability implies duality! Clockwise is dual to anti-clockwise. Left brain dominance is dual to right brain dominance. Master (Lordship) is dual to slave (Bondsman) -- the time dependent Hegelian dialectic. Brain dominance is visual proof of the Hegelian dialectic at work, problem, reaction, solution. The Hegelian (Fichte's) dialectic is dual if it is dependent & independent of time (both at the same time):- Thesis (action, problem) is dual to anti-thesis (reaction) creates the converging thesis or synthesis (solution) -- the time independent Hegelian dialectic. Action is dual to reaction -- Sir Isaac Newton (the duality of force or all forces are dual). Mind (the internal soul, syntropy) is dual to matter (the external soul, entropy) -- Descartes. Syntropy (prediction) is dual to increasing entropy -- the 4th law of thermodynamics! Teleological physics (syntropy) is dual to non teleological physics (entropy). "Always two there are" -- Yoda. Duality creates reality! The Necker cube is a good example of duality. From a converging, convex or syntropic perspective everything looks divergent, concave or entropic -- the 2nd law of thermodynamics! All observers have a syntropic perspective. Space is dual to time -- Einstein. Time symmetry is dual to time asymmetry -- time duality. Space symmetry is dual to space asymmetry -- space duality. Time duality is dual to space duality. Energy is dual to mass -- Einstein. Dark energy is dual to dark matter. The Big Bang is a Janus hole/point (two faces = duality) -- Julian Barbour physicist. Topological holes cannot be shrunk down to zero -- non null homotopic. Null Homotopic is dual to non null homotopic -- Duality.

[@BartdeBoisblanc]

The part about a closed system is where some people get confused. An open system can allow energy in from outside itself a closed system can't.

[@YisusBlakSpp]

I have one puzzling question to me. How is gravity, a force that tends to concentrate mass in a single point, contributing to the overall *increase* in entropy? You'd think that higher entropy would imply matter scattered diffusely rather than focused.

[@ThatCrazyKid0007]

Because gravity isn't the only effect at play, in fact it's the effect that contributes to entropy decrease. There is a negative pressure effect in the universe, currently coined dark energy which little is understood about, that drives mass distribution and therefore mass distribution towards a diffuse state, so opposite of what gravity tends to do. The disbalance in the strength and magnitude of the way these effects can affect the system dictates towards which state the system is heading towards on the grand universe scale.

[@michaelsanders8961]

Are our cells affected by gravity or just our bodies? Meaning they flow all around without a need for gravity. And inside cells atoms and protons etc do the same thing. It's the observable plane we are on.

[@guytech7310]

@@ThatCrazyKid0007 Objects trapped in a gravity field can be consider as pocket of trapped entropy, like water trapped in a cup. However give enough energy from an external force can release trapped entropy. For instance if another large mass traveling very fast hits the earth it can scatter matter out of the earths gravity well. Although the matter trapped on earth still undergoes entropy (for instance chemical reactions: burning fuel). The Earth does constantly gain energy from the sun (external source), to offset energy losses.

[@MusicalRaichu]

this is a really good overview! i think i learned more from this simple presentation than from the explanations on more nerdy physics channels!

[@DanielL143]

Best explanation ever, with one small flaw. The word 'time' is used to describe two different phenomenon on two different scales. There is (1) the phenomenon of time as the relative rate of physical change on the microscopic level that varies locally - change being the essence of reality as observed by the Greeks and other ancient cultures and therefore a fundamental aspect of the interplay of fields, and (2) the use of the term on the emergent macro scale which relates to the general average direction of the evolution of large complex systems and the universe as a whole. Wittgenstein warned us that problems and apparent paradoxes arise from the misuse of language. Nature has no paradoxes, only the human mind would allow us to confuse (this is why scientists should take a class in philosophy, sorry Feynman). Thanks so much! (We should refer to little t and big T and distinguish between the two to avoid these silly issues). Little 't' is directionless but big T' consolidates aggregate change to create the arbitrary arrow of time. Memory permits us to experience big T and our emotional state determines the rate of the experience of Time.

[@byronwatkins2565]

First, the premise that reversing all velocities (momenta) produces an equally likely state has no support. One thing the laws of physics definitely forbid is precisely this... every action requires an equal and opposite reaction and momentum was not conserved in any one of these spontaneous reversals. I do understand that the premise is that the system might "begin" with this as its initial state; however, memories of past events imply that all such "beginnings" are merely continuations of previous states and interactions. We can contrive systems that spontaneously reduce entropy but no such process has been observed to occur without explicit intervention. Second, it is conceivable that our universe's evolution might one day be described as a quantum wavefunction oscillating through the eye of a big bang 4D singularity -- not so different from an electron wavefunction oscillating through an atom's nucleus. Such self-similarity and scale invariance, in fact, is an essential part of complex systems. Third, if this is a valid explanation of our past and future, then we must surely be curious what will become of the matter and energy that has already expanded beyond our light cone. Is this possibly analogous to an atom ionization event? Or is it possible that sinh() and cosh() rather than sin() and cos() model our universe's past and future? Perhaps our space-time has confinement in common with quarks such that stretching it more simply creates new particle-antiparticle pairs.

[@stickmasterlukeRBX]

Who is to say that the big bang wasn't just a really uncommon deep valley in the time-entropy graph, one that occurs eventually and infinitely many times?

[@hyperduality2838]

There is also a 4th law of thermodynamics, watch the spinning dancer:- kzbin.info/www/bejne/i5KraIt3fbR7r6c Bistability implies duality! Clockwise is dual to anti-clockwise. Left brain dominance is dual to right brain dominance. Master (Lordship) is dual to slave (Bondsman) -- the time dependent Hegelian dialectic. Brain dominance is visual proof of the Hegelian dialectic at work, problem, reaction, solution. The Hegelian (Fichte's) dialectic is dual if it is dependent & independent of time (both at the same time):- Thesis (action, problem) is dual to anti-thesis (reaction) creates the converging thesis or synthesis (solution) -- the time independent Hegelian dialectic. Action is dual to reaction -- Sir Isaac Newton (the duality of force or all forces are dual). Mind (the internal soul, syntropy) is dual to matter (the external soul, entropy) -- Descartes. Syntropy (prediction) is dual to increasing entropy -- the 4th law of thermodynamics! Teleological physics (syntropy) is dual to non teleological physics (entropy). "Always two there are" -- Yoda. Duality creates reality! The Necker cube is a good example of duality. From a converging, convex or syntropic perspective everything looks divergent, concave or entropic -- the 2nd law of thermodynamics! All observers have a syntropic perspective. Space is dual to time -- Einstein. Time symmetry is dual to time asymmetry -- time duality. Space symmetry is dual to space asymmetry -- space duality. Time duality is dual to space duality. Energy is dual to mass -- Einstein. Dark energy is dual to dark matter. The Big Bang is a Janus hole/point (two faces = duality) -- Julian Barbour physicist. Topological holes cannot be shrunk down to zero -- non null homotopic. Null Homotopic is dual to non null homotopic -- Duality.

[@thisis87]

This lady is amazing. The clear description and visuals are great. Also she is the most cheerful physicist/ mathematician I’ve ever seen.

[@blacksmith67]

I have a great deal of difficulty with time symmetry. Here is a thought experiment that I came up with a few years back: Picture a room with normal air and simple hard surfaces. The temperature throughout is in equilibrium. At some point the gas and solids of the room start to spontaneously differentiate in heat energy until some significant clusters of molecules begin to vibrate in unison. The molecules’ motion increases in intensity until waves, very small at first but increasing in scale are launched in chaotic directions from the walls and air. Then these waves, fuelled by greater amounts of heat converted to kinetic energy increase in intensity, picking up more energy as they reflect off surfaces, becoming sound waves. Faint at first they grow and coalesce until they reach the centre of the room where they move shards of glass that are at rest. The conversation of heat from the walls into sound waves increases until these too coalesce into strong waves at the centre where glass is suddenly rocked and then launched into the air where it _unshatters_ to form a single piece vase that leaps from the floor in the suddenly silent room to alight on the edge of a shelf and come to a rest. Every bit of chaotic sound and motion being transferred to the potential energy of this precariously placed vessel. A minor vibration in the shelf moves the vase from the point of tipping to a point of complete rest just shy of tumbling. I can no more calculate the probability of this happening as I could calculate the likelihood of a chick spontaneous _unbreaking_ back into an egg and that egg getting sucked back into a bird to be _unformed_ and _undigested_ into food that is regurgitated into a living grub or worm. I may be out on a limb here, but for this and a few other reasons, I don’t believe that spacetime is deterministic. I also don’t hold that a lack of determinism violates any law of physics, nor that there is any contradiction in this position. I contend that if a cue ball strikes a break on a pool table and scatters the balls, that if the exact same conditions right down to the state of every molecule in the universe was reset and the break done again, that the resulting position of the balls would be different. The reasons I hold this position are difficult to explain, but are not based on any wiggle room arising from quantum effects. It has more to do with the the lack of significant impact between the micro and macro states and energies being so distant from each other in effect as to leave complete room for chaos as an emergent property.

[@peterchema7011]

1:40 when tossing balls in the air, you could estimate relative locations based on coriolis effect with a precise and powerful enough instrument (objects moving along a north-south path undergo an apparent westward deflection in the northern hemisphere, and eastward deflection in the southern hemisphere, coriolis effect differs depending on latitude, technically possible but altogether impractical)

[@coobit]

A gem of a video. Thanks for the work.

[@laurendoe168]

If you define "time" as the increase of entropy, then yes, it is logical to believe time can go backwards. If, however, you define "time" as simply the variable that allows entropy to happen, time cannot go backwards. Just because you observe entropy decreasing does not mean time is going backwards. If time was going backwards, it would be going backwards not only for what you are observing but also for you. While going backwards in time, you would observe entropy increasing because your view of entropy would also be reversed.

[@SpydersByte]

this honestly makes more sense to me than the entire video did.

[@jeffryglenn7024]

Unfortunately for you explanation, the claim made by the video is that the direction of time is not dependent on your observation of it. Much in the same way that you would be unaware of the slowing of time as you approach the speed of light.

[@laurendoe168]

@@jeffryglenn7024 While true... this raises interesting questions, like: If there are no observers, does time even exist? Can you prove entropy decreased? Can you prove that the direction of time changed when entropy decreased?

[@jeffryglenn7024]

@@laurendoe168 Or why accept entropy as a measure of time?

[@jeffryglenn7024]

@@laurendoe168 One key point overlooked in the video: as we move from low to high entropy, we don't see reversals. Only upon reaching equilibrium do we see rare "highly improbable" temporary reversals. From this we can infer 2 things: 1. entropy is a poor way to measure time given the most "probable" state is equilibrium; and 2. so long as the universe continues to expand from low to high entropy (in its pursuit of equilibrium) we won't need to concern ourselves reversals any time soon!

[@78dentedhead]

Hi Jade, just found this channel. Awesome explanation about time here! Subbed and notifications on, looking forward to seeing more Up and Atom content :)

[@Inverted-Compass]

Time is a scalar (a scalar is an element of a field which is used to define a vector space.) which is the same in all space E³ and is denoted as t. The ordered set { t } is called a time axis. Motion (also path or trajectory) is a function r : Δ → R³ that maps a point in the interval Δ from the time axis to a position (radius vector) in R³.

[@YourLocalCafe]

Hey Jade, i had been struggling with the concept of Entropy for a while now, but just as you introduced it with the better definition my problem got solved in an INSTANT. I cannot thank you enough for your help, by the way do you have any intuitive explanation for state and path functions in thermodynamics as well?

[@upandatom]

I’m glad it finally clicked! Unfortunately I don’t at this time

[@YourLocalCafe]

@@upandatom thank you so so much and it is fine that you do not at the moment have the explanation, I assume you must be occupied with other important things. Keep it up! :>

[@hyperduality2838]

There is also a 4th law of thermodynamics, watch the spinning dancer:- kzbin.info/www/bejne/i5KraIt3fbR7r6c Bistability implies duality! Clockwise is dual to anti-clockwise. Left brain dominance is dual to right brain dominance. Master (Lordship) is dual to slave (Bondsman) -- the time dependent Hegelian dialectic. Brain dominance is visual proof of the Hegelian dialectic at work, problem, reaction, solution. The Hegelian (Fichte's) dialectic is dual if it is dependent & independent of time (both at the same time):- Thesis (action, problem) is dual to anti-thesis (reaction) creates the converging thesis or synthesis (solution) -- the time independent Hegelian dialectic. Action is dual to reaction -- Sir Isaac Newton (the duality of force or all forces are dual). Mind (the internal soul, syntropy) is dual to matter (the external soul, entropy) -- Descartes. Syntropy (prediction) is dual to increasing entropy -- the 4th law of thermodynamics! Teleological physics (syntropy) is dual to non teleological physics (entropy). "Always two there are" -- Yoda. Duality creates reality! The Necker cube is a good example of duality. From a converging, convex or syntropic perspective everything looks divergent, concave or entropic -- the 2nd law of thermodynamics! All observers have a syntropic perspective. Space is dual to time -- Einstein. Time symmetry is dual to time asymmetry -- time duality. Space symmetry is dual to space asymmetry -- space duality. Time duality is dual to space duality. Energy is dual to mass -- Einstein. Dark energy is dual to dark matter. The Big Bang is a Janus hole/point (two faces = duality) -- Julian Barbour physicist. Topological holes cannot be shrunk down to zero -- non null homotopic. Null Homotopic is dual to non null homotopic -- Duality.

[@AquarianSoulTimeTraveler]

@@upandatom @Up and Atom you are such a living walking piece of garbage I can't believe you just took this video and spun it into anti Big bang propaganda BS! One of the biggest problems with third dimensional existence is the fact that we think that whatever we can see we can measure accurately... This is completely untrue! If we sent out a enormous amount of spaceships that we could actually accurately track the distance in which they have traveled from this Earth and we mapped our entire galaxy it would be nothing but a tiny little speck compared to the entire universe of everything we can see. Accelerating expansion of the universe pass the speed of light and constantly picking up speed is an illusion caused by dark matter... Contrary to popular belief dark matter does interfere with regular matter. I think it's pretty audacious of the scientific community to say that dark matter has no interaction with regular matter when they haven't even identified what dark matter is comprised of and have never even found a dark matter particle!!! Everything bust forth from the singularity the problem is science wants to move itself away from the singularity because it realizes that the singularity is "God". Ultimately everything is one. Dark matter is the counter action force to the expansion of the universe... Let's say that dark matter is comprised of hooks instead of strings. This is the reason why we cannot view a dark matter particle and I've never found one because we are composed of strings these hooks can rip off tiny fractions of those strings of all material that pass through it and convert it into hooks. Light has mass this is the reason why I like cannot escape a black hole it is mass in motion when it comes to a resting point it no longer contains mass and it no longer exists. Light sheds its mass to maintain its velocity just like everything else. The reason why light cannot escape a black hole is because guess what it contains Mass anything that contains volume contains Mass... You cannot give something volume without giving it Mass! If you take a two-dimensional plane and you put it in any direction in any position near a black hole wherever you want to put it it will have absolutely zero interaction with a black hole! Do you know why because guess what in the second dimension there is absolutely no mass and therefore black hole cannot have any interaction with that two-dimensional plane! I'm not disagreeing with you on the fact that time can reverse and roll backwards but to think that anything ever started from anything other than a singularity is just insanity! This anti Big bang mindset is totally insane! Also this accelerating expansion of the universe pass the speed of light mindset is equally insane! And I completely understand what the idiot say about how since it is expanding into nothing it can pick up speed past the speed of light but that's just total garbage! Dark matter is absorbing bits and pieces of all energy that pass through it it is surrounding our entire solar system our entire galaxy and is constantly growing by absorbing bits and pieces of energy that pass through it ripping off strings fractions of a penny of mass and slowly increasing it's density... This is happening equally as this does happen and dark matter increases its density it creates an illusion of accelerating expansion of the universe past the speed of light! It is far more logical and far more reasonable to say this than to say any of the BS that people spout about anti Big bang! Sorry but I just couldn't let you get away with it especially when you leave it on a cliffhanger like that and obviously really don't know anything... There's a reason why your video got pushed to me by the KZbin algorithm because it's nothing but BS propaganda anti Big bang anti-singularity anti-god BS crap! Then again none of us are immortal beings that have existed from the very beginning of time and will exist to the very end of time so none of us can experience real objective truth and objective truth does not exist here in the third dimension... So guess what I'm wrong and you are wrong and every single person here will be wrong and it is completely pointless to even try to figure anything out because guess what they will be wrong too!!!!

[@galenburnett9791]

@@hyperduality2838 james joyce did this sort of thing. only his references i think all were coherent. i don’t have the time to check all yours unfortunately.

[@ElvenScholarMusings]

Ah, I look forward to the day when it is realized that "Time" does not exist but is merely our "perception" or reaction to the flow of space around (through) us. The Lorentz transformations do a wonderful job at displaying this fact. As our relationship to the flow of space changes due to our velocity, so to speak, so does our perception of "time". There is no actual flow, in any direction, it is but our interpretation of the passage of events in relation to space itself and the speed by which it is expanding ...

[@bariamtak]

Exactly. Been saying this since as long as I can remember. But "researchers, scientists, KZbinr" Need complex space time equation.

[@randomtester3442]

@Anubis Priest except in reverse, there's radioactive build-up. :-B

[@EduardoMartinez-fk2pv]

Doesn't all that the lorentz transformation displays is that the subjective perception of time? Also you speak about speed and movement being the source of the illusion of time, but movement is the change of location in time, if there's no time, in what "medium" is the change of position taking place?

[@ElvenScholarMusings]

@@EduardoMartinez-fk2pv That is exactly what I am talking about with time begin subjective but also objective, depending on the point of view of the observer. As for movement being a change in location depending on time, again, simply a point of view. As quantum mechanics has shown us, it is not always as it appears. Posting here is not an adequate forum for a more detailed discussion of our interactions with the fabric of "space" and our observations of that perception. Thank you though for your observation. :)

[@garyfilmer382]

All wonderful! The enigma of time continues to provoke us to speculate in wonderment, because it is so incredible! Thank you for this video!

[@photelegy]

11:49 This part really reminds me of anti-matter. Here the valleys are back and forth likely and it always seems like the other direction is backwards. Like matter or antimatter have the same rules and just because we (and almost everything) are made out off matter. But if there would be an antimatter-galaxy they could argue in the same way.

[@IXSigmaXI]

Yes thats true! antimatter behaves exactly as normal matter going backwards in time. Some might say that an annihilation event of a electron-positron pair looks identical to a solitary electron making a U-turn in time. Since the net charge of the universe is 0, you might imagine a single electron making its way backwards and forwards between the big bang and every eventual annihilation event, no matter how far in the future, accounting for every single element of charge in the cosmos. (except all the loops of pair production and annihilation)

[@techman2553]

I always wondered if the matter / anti-matter imbalance was due to simple geometry. If at the time of the Big Bang, an equal number of matter and anti-matter particles were created, and they interacted, any imbalance would cause one to dominate over the other. So the question becomes - is it physically possible for pairs of particles and anti-particles to be distributed in a cloud of expanding 3D space and remain balanced in every way, within each pair and between different pairs ? - Maybe it is mathematically impossible for a pair-balanced distribution cloud to hold in 3 dimensions. For example, take a sphere or bubble, can you have 2 different colored dots in equal amounts, say red and blue, exactly equidistant to each other and equally distributed around the surface of the sphere ? A pair imbalance might be mandatory for 3 dimensional geometry. I'm sure that someone with stronger math skills than I could try and model it.

[@blkk_mamba]

Superb work, Jade! To me, the best presentation of a topic by you till now. You spoke in just the right manner and with the right pace. Keep it up! 👏👏

[@upandatom]

Thank you that means a lot!! :)

[@Omlet221]

Nice quote at the beginning. I think it can apply more generally about how it’s easy for us to think we know things cause they seem right when we really don’t fully understand.

[@justinma1728]

This is such an interesting topic! I thought it was particularly interesting that Boltzman did his PhD on the Kinetic Theory of Gasses which is still something we learn today. It seems like it was much easier to have a sweeping impact on a field of study in the past then it is now. Topics today seem very specialized. That got me wondering...what field of study has the highest impact today?

[@hyperduality2838]

There is also a 4th law of thermodynamics, watch the spinning dancer:- kzbin.info/www/bejne/i5KraIt3fbR7r6c Bistability implies duality! Clockwise is dual to anti-clockwise. Left brain dominance is dual to right brain dominance. Master (Lordship) is dual to slave (Bondsman) -- the time dependent Hegelian dialectic. Brain dominance is visual proof of the Hegelian dialectic at work, problem, reaction, solution. The Hegelian (Fichte's) dialectic is dual if it is dependent & independent of time (both at the same time):- Thesis (action, problem) is dual to anti-thesis (reaction) creates the converging thesis or synthesis (solution) -- the time independent Hegelian dialectic. Action is dual to reaction -- Sir Isaac Newton (the duality of force or all forces are dual). Mind (the internal soul, syntropy) is dual to matter (the external soul, entropy) -- Descartes. Syntropy (prediction) is dual to increasing entropy -- the 4th law of thermodynamics! Teleological physics (syntropy) is dual to non teleological physics (entropy). "Always two there are" -- Yoda. Duality creates reality! The Necker cube is a good example of duality. From a converging, convex or syntropic perspective everything looks divergent, concave or entropic -- the 2nd law of thermodynamics! All observers have a syntropic perspective. Space is dual to time -- Einstein. Time symmetry is dual to time asymmetry -- time duality. Space symmetry is dual to space asymmetry -- space duality. Time duality is dual to space duality. Energy is dual to mass -- Einstein. Dark energy is dual to dark matter. The Big Bang is a Janus hole/point (two faces = duality) -- Julian Barbour physicist. Topological holes cannot be shrunk down to zero -- non null homotopic. Null Homotopic is dual to non null homotopic -- Duality.

[@cubicinfinity2]

Hard question to answer. I can only make suggestions. I think computer science has a lot of progression still and we might be getting into a new wave of it.

[@cubicinfinity2]

Maybe neurology + psychology?

[@meribarseghyan842]

This is a really interesting video. I have never thought before that time may flow in both ways. The fact that we can deduce that it is possible is fascinating, but I hope we will have more proof for this assumption in the future. Thanks for the video and your effort😊.

[@n2185x]

I have a suspicion of why time seems to flow in one direction. It's because of quantum mechanics. More specifically, the probability of a quantum transition in one direction *is not* guaranteed to be the same as the probability of the reverse transition. For instance, the probability that an electron will jump from a lower energy orbital to a higher energy orbital is *lower* than the probability that it will jump from that same higher energy orbital to that same lower energy orbital. The latter has a higher probability. This quantum transition asymmetry gives events in the universe an inherent direction at the quantum level. And if events have an inherent direction at the quantum level, they *must* have that same inherent direction at the macro level, since macro level events are just the amalgamation of vast numbers of quantum events. What we see as time is, if I'm right, indeed just an emergent property of the asymmetry of quantum transition probabilities.

[@paulakinsella2359]

All times exist all at once .

[@Kaepsele337]

@@n2185x This is incorrect. The time evolution operator in quantum mechanics is unitary, i.e. the probability that an electron will jump from the higher orbital to the lower is exactly the same as the reverse. An asymmetry only comes from the fact that it could spontaneously emit a photon while jumping down, while it has to absorb a photon to jump up. Which way is more likely depends just on how many photons with the correct amount of energy there are around the atom, i.e. the entropy of the environment. This however is the same situation as in classical physics, where the fundamental processes are time reversible, and the time direction comes just from the low entropy of the initial state. An atom with the electron in the high orbital with no photons around is just a low entropy state.

[@n2185x]

@@Kaepsele337 That's a good point, but it doesn't change the overall conclusion. In this case, the total probability of a jump from a lower orbital to a higher one is the combination of the probability of absorption of a photon *and* the probability of jumping up in the event of such absorption, plus the probability (which might be zero) of a spontaneous jump without such absorption, whilst the probability of jumping down is that alone. The two aren't equal in the general case, which means the probability of the event reversal is unequal in the general case and *that* is what gives us a time direction. The example I gave that you responded to is but one example. Nuclear decay is another example. The probability of an atom of a heavy, unstable element spontaneously decaying into a set of lighter atoms (and other things) is far lower than the probability of those smaller things spontaneously combining together to yield the heavier element, given the same environmental conditions. The point of this is that whenever you have an asymmetry of probabilities in opposite events, you *automatically* get an arrow of time as a consequence. And since that asymmetry of probabilities exists at the quantum level, you'll get an arrow of time in the macro-scale domain as an emergent property.

[@Kaepsele337]

@@n2185x Yes, but that's just the same old entropy increase that you also get classically, it's not about QM specifically. Take a look for example into cosmology, it's discussed a lot there in the context of recombination for example. In a high temperature environment (thus high entropy) you have a lot of photons such that at equilibrium the reverse of the process is equally likely. Your example of nuclear decay is the same way, the initial condition is simply low entropy, which is what gives the asymmetry. The point in both examples is that particle number is not constant, thus you have to consider the particle density of the environment for the entropy of the system. The transition matrix element is the same for either direction of the process (that's a very fundamental property of qm called unitarity) the only asymmetry comes from choosing a very peculiar initial condition, i.e. one where there are no photons in the environment. Or neutrons and electrons/positrons in the case of nuclear decay.

[@triplec8375]

Fun video! Thanks very much! As Rocky Kolb once said, in cosmology "topology is everything". And there may, indeed, be a topology for the universe that could explain some of the toughest questions in physics today. With the right topology, we can have not only the conservation of mass/energy and angular momentum, but conservation of space and time. Yes, that does allow for time to "flow" both directions, keeping in mind that there is no forward or backwards movement in time, only relative differences in time. Along the way, we might answer things like "Where's all the antimatter?" and "How can the universe start out with such low entropy at the Big Bang?" and even "How does the Universe end?" But to do so, physicists need to take a good hard (and healthy, IMHO) look at some assumptions and biases currently in effect,. For instance, the easily accepted, but not critically examined, statement that time cannot be a 4th spatial dimension because of the Inverse Square Law. In keeping with the title of this video, there are biases that keep physicists from examining the notion of time flowing both ways. I heard a nationally recognized physicist state on NPR that physicists don't want to accept (or admit) the bidirectional flow of time because of the potential ramifications (scrambled eggs recovering into the shell, people rising from the grave, billiard balls coming out of the pockets and reassembling into the break triangle, etc). Yet, those same physicists will treat a positron as an electron moving "backwards" in time. Some re-examinations of the basics will have to happen before the physics community really talks about time flowing bidirectionally outside of a Feynmann diagram.

[@pierfrancescopeperoni]

I would say we are in a lower entropy state because consciousness needs it to exist. The perceived direction is that towards equilibrium because the interaction between the brain and the environment makes it possible for information only to be gained while going towards equilibrium. The perception of time must be internal to the dynamics, which makes it difficult to look at time by an external point of view. Of course I'm an eternalist and don't believe in flow of time, otherwise the above would make no sense.

[@evilpandakillabzonattkoccu4879]

I used to think "if we were going backwards in time, how would we know?" it's not like driving forward, then backwards in a car since you have memory of going both ways. memory creation, however, is our brain recording changes over time, so if we were going back in time we would be unlearned things or unexperincing events. we wouldn't know, for example, that we were before the "Current Global Politial Conflict" (as that seems to be nearly a human constant) if we didn't know it was about to happen. You would to have experience invasion of Poland and known it would start WWII in order to tell that you were back before WWII. I don't think you'd keep memories going backwards in time. .....then again: my opinion isn't worth a thing, so I'm pretty much just an idiot talking nonsense.....a nonessential, useless sound.....like a caged crow's call.

[@upandatom]

I don’t think life could exist in decreasing entropy

[@harshaveluru2402]

@@upandatom If we think about it..living systems are eddies of low entropy in an ocean of increasing entropy..so wouldn’t it be more likely for life to exist..?🤔

[@evilpandakillabzonattkoccu4879]

@@upandatom Thank you! 👍 I assume you're correct ... and, even if I thought you were mistaken, I'm not educated enough to know either way. 🤷‍♂️😄 I trust your assessment. Thank you for the response!👍

[@evilpandakillabzonattkoccu4879]

@@harshaveluru2402 I used to frame houses with my dad most school days and most weekends as a kid. To motivate me to stay in school, my dad would wait until I was sore and tired from working, then he would repeat this old PSA quote: "miss school, miss out, huh?"...... .....this 'me being unable to even really participate in the conversation in a meaningful manner' issue.... that's the "missing out" part he was talking about....

[@specialrelativity8222]

I was thinking similarly. time going forward is creating memories so time reversal will erase that memory.

[@bryanmorwood]

I like Jade’s entropy at equilibrium drawing, where ‘decreases in entropy happen just as often as increases.’ (11:50) But surely it is unnecessary to equate the dips in entropy with going backwards in time? My physics teacher at school used to say, ‘If you put a kettle on the gas, there is a small chance that the water in it will freeze rather than boil.’ The chance is, of course, infinitesimally small, but the point was to stress the statistical nature of entropy. My teacher never claimed that when the water froze, it was going back in time. It wasn’t, it was just very improbable.

[@TrueCrazyLion]

Open-mindedness is truly a gift. 👌 What a fascinating, thought-provoking video! Great work Jade! 🙌

[@DanielF601]

Congrats on another great video. However, you lost me when you casually equated decreasing entropy with backwards time flow. On the face of it, the argument that entropy is just as likely to decrease as increase doesn't seem to equate to the statement that time could run in either direction (as distinct from the statement that we would not be able to tell just by looking). I'm also scratching my head over the decreasing entropy example, which tracks the motion "backwards" to a low entropy state but then conveniently stops at that point. In a continuous-time system, the particles would continue moving through that one moment of low entropy, and the entropy would then be increasing again... most likely forever.

[@sophisticatednebula4236]

Unless I'm missing something, that was the point, that if we observe entropy decreasing, that does NOT mean that time is flowing backwards.... The initial theory of entropy suggested that that was the case was, but upon further inspection we find that entropy is also symmetric.

[@joekingston822]

the distance in space between two objects is directly perceived by me (subject to assumption correponds well with external reality - see Hume & Mach). the monotonic increasing time is directly perceived by MEMORY - even if A occurs before B, if my perception of B occurrs first, then I can remember B when I perceive A. statistical nature of 2nd td law interesting but case for it puzzling - setting up 1-1 correspondence between states doesn't male probabilities equal; maybe there's a duration in low entropy states that is systemically shorter than high entropy because of collisions.

[@bryanreed742]

I get the impression that some time in the last couple of years you took a step back and really thought hard about how to improve both the depth and accessibility of your videos. If so, I have to say that the effort paid off in a big way.

[@dragonsouldevlog3982]

Is time bisexual?

[@jan-pi-ala-suli]

lmao

[@natedogtrainer3812]

That assumes two genders. It’s poly

[@laradrekko8928]

I love when the KZbin algorithm churns out a new channel at me to obsess about. BEAUTIFULLY DONE VIDEO. I can’t wait for more.

[@naveenrajukopparthi3046]

Thank you Jade, please do more videos.

[@georgcantor8859]

Interesting video, but one problem. Entropy is a state probability. For example, if all the atoms in a room are arranged in a corner equidistant to each other in a cubic manifold. That's really really low entropy. As soon as the clock ticks, they will start to disperse. After a while they will tend to be evenly distributed to the volume of the room, which is high entropy. The problem is the number of vectors each atom must take to return to its low entropy state is significantly lower, probably by immense orders of magnitude, than the number of vectors to move the atoms to the next evenly distributed state. Therefore the probability of moving from one low entropy state to another is so high that, I suspect for an average sized room (guessing here) that you'd have to wait longer than the age of the known universe for it to happen. It is a non-zero probability, of course, but so close to zero if you squint you'd miss it.

[@SteveTaylorNZ]

Thank you Jade, this video rocked my worldview like nothing else in 30 years of following popular science and maths topics.

[@videos_not_found]

Clausius succeeded in a coining a Word that means the same to everyone: Nothing. Leon Cooper ...Thank you Jane, this is great educational stuff!

[@helifynoe9930]

So, picture a bulb that is attached to a battery. The battery creates a DC current that goes through the bulbs filament, creates heat, and enough to also release visible light. But it is at times said that time could go backwards without breaking any laws. So, there would be a bunch of photons heading toward the bulb, heating the bulbs filament up, and magnificently also creating a electron current flow that goes in one specific direction. Amazing.

[@KrustyderkleineKraut]

I've never experienced anyone pronounce the word "collisions" nearly as lasciviously as Jade did at the 6:06 time point in the video. It gave me shivers.

[@craigcorson3036]

I have long maintained that the flow of time may constantly (or, I suppose, inconstantly) be speeding up, slowing down, and reversing direction, and that we would have no way of detecting these changes, either directly or with instruments, because we and our instruments are embedded within time, and thus would experience the flow of time in exactly the same way regardless of its speed and direction.

[@jean-baptiste6479]

Time reversability is purely theoric. In practice, if you reverse time simultaneously everywhere in the universe there are two big problems : -simultaneous does not mean a thing -some events are random : if you reverse time even very locally, there is no reason why the events will take place at the same time before time reversion. This is enough a perturbation to avoid things to actually roll back

[@deceptivebark671]

6:35 I like to imagine ghosts just spectating the universe waiting for a gas to bunch up like when everyone stares at a television waiting for the logo to go in the corner. “Here it comes!… oh wait… ALMOST!”

[@NathanSMS26]

My BS is in physics so its not often I actually learn from youtube videos on it, but I still enjoy them. But saying entropy is like a measure of distance from equilibrium is so much better than it being a measure of Order

[@gireeshbabuv]

Time always goes forward and backwards directions but we can only experience time moving forward because we can't separate ourselves or anything from the universe. Even if time is just moving backwards from end of the universe to begining right now we can still only experience the way we experience time now.

[@seanmostert4213]

A suggestion on the Big Bang: If the universe was a doughnut (torus) shape or an hourglass (double stacked torus) shape, which happens to be the same shape as a magnetic field or a planetary geomagnetic field. If there was flow direction through the centre of it like the right hand rule, then from the centre towards on one end of it you would experience a divergence effect where the universe would be expanding after what appears to be a big bang, and on the other side there is a convergence event where the universe gets siphoned in and crushed down to a singularity.

[@abhishekshah11]

CCC by R. Pensrose offers a very nice explanation as to why the past appears such a low entropy state. It's not a special state rather a phase in the eternal inflation of the larger universe ( a priori assumption) , forever expanding., creating pockets of low entropy that may appear gravitationally uniform and hot from the perspective of the child universe. Very fascinating idea. Although I'd also like to point out that a discussion on the nature of time just based on classical notions like entropy and classical motion is still limited. In my opinion, one must take into account the unitary evolution of the wavefunction, start there, and then build up this increasing entropy universe, by noting that through subsequent reductions of the wavefunction as it evolves, selecting from an ever narrowing range of possibilities, we introduce a kind of asymmetry in the objects of measurement one way rather than the other.

[@clivemitchell3229]

Almost any low-entropy state when altered slightly will still have a high probability of continuing towards a higher entropy state. However, any high entropy state moving towards a (coherent) low entropy state, if altered slightly, is probably going to become chaotic and not move towards the low entropy state. I suggest there are more low entropy pathways than high entropy ones, but I'm no physicist.

[@stampedetrail2003]

When forces balance, such as within a star that is fusing vs. the gravity holding it together, entropy decreases.

[@4xelchess905]

It is not necessarily the case that reversibility should imply that entropy should decreases as often as it increases. From an information stand point, states of higher entropy are exponentially more numerous than states of lower entropy, because the number of states you can describe grows exponentially with the length of the description (the entropy). Because of that, considering a chaotic reversible dynamics over the states and sampling a state at any given entropy is more likely to have entropy increase than decrease, because there are more states of high entropy to be paired up with. In a finite boundedsystem, once it reaches close to the maximum entropy, entropy does decrease as often as it increases, just not noticeably so. And it would eventually decrease according to Poincare recurrence theorem, just not within realistically observable times. But for an infinite or an expanding system, it doesn't even have to be the case.

[@bestview2397]

But I have queries: 1. If we throw ball in earth and in moon, won't we know where we are in space from the different ways of the ball behaves? 2. In earth if entropy increases it means time flows forward, but in saturn if entropy decreases time flows forward and not backward. Am I right?

[@joesands3350]

TIME = comparing the motion of the clock vs movement of earth, it requires a recording device or memory = duration of motion in space TIME INTERVAL = the spacetime separation between 2 events that occur at the same place Amrit Sorli's work which re-formalizes Einstein's relativity equations in terms of 3D space NOT 4D space-time. Time (I think correctly) is defined as: "the duration of motion in space" - it only requires memory & motion. So the time we measure with the clocks is the numerical order of events. The fundamental unit of time is Planck time. Every elapsed time (duration) is the sum of Planck time: t = tp x n, where n is a finite natural number. Taken from the article: " In their paper, Sorli and Fiscaletti argue that, while the concepts of special relativity are sound, the introduction of 4D Minkowski spacetime has created a century-long misunderstanding of time as the fourth dimension of space that lacks any experimental support. They argue that well-known time dilation experiments, such as those demonstrating that clocks do in fact run slower in high-speed airplanes than at rest, support special relativity and time dilation but not necessarily Minkowski spacetime or length contraction. According to the conventional view, clocks run slower at high speeds due to the nature of Minkowski spacetime itself as a result of both time dilation and length contraction. But Sorli and Fiscaletti argue that the slow clocks can better be described by the relative velocity between the two reference frames, which the clocks measure, not which the clocks are a part of. In this view, space and time are two separate entities. “With clocks we measure the numerical order of motion in 3D space,” Sorli told Phys.org. “Time is 'separated' from space in a sense that time is not a fourth dimension of space. Instead, time as a numerical order of change exists in a 3D space. Our model on space and time is founded on measurement and corresponds better to physical reality.” " p.s. one comment re: measurements (that many physicists use, incorrectly, as evidence for understanding) - just because we have measured a parameter e.g. the gravitational constant to the nth degree does NOT mean we understand its physical derivation.

[@melissarainchild]

Finally, a video that is not a "cut-n-glue" affair, nicely brought in one stream...