When Conservation of Energy FAILS! (Noether's Theorem)

[@AndrewDotsonvideos]

Really helpful as I insist on only learning through squirrel motion examples.

[@ScienceAsylum]

I saw your "Undergraduate vs Graduate Physics" video a while back and laughed so hard I got hiccups.

[@Eigenbros]

A wild Dotson appears 😎😎

[@johnbode5528]

@@ScienceAsylum "what exactly _is_ spin?" got me.

[@AdityaKumar-ij5ok]

@@ScienceAsylum you and Andrew should definitely do a collab(any topic), it will be a must watch for me!!

[@krishnasimha8097]

Hey Andrew

[@DanteKG.]

Emmy Noether is quite likely the most intelligent person of the 20th century. Brutally intelligent.. Physics had a crisis that no one could solve so they asked her for help.. She proceeded to formulate her theorem which links continuous symmetries to conservation laws. Her field is abstract mathematics (abstract algebra to be precise) and was described as reasoning about operators in a completely different way than her peers. She was a professor in the most prestigious math college in germany but because women weren't allowed to teach at college back then she had to officially work under the name of a collegue and without pay... For years the most brilliant mathematician was teaching students at the top faculty for mathematics and she did it for free

[@ScienceAsylum]

Her contributions were revolutionary.

[@Warlord_Megatron]

Thanks for the info :)

[@MattMcIrvin]

Noether's Theorem to physicists is like water to a fish. It's just everywhere.

[@educatedguest1510]

Conservation of energy does not work only with time dilation, and works perfectly within absolute time. And so are all Newton's laws, momentum conservation, and even particles entanglement. Check "Is Energy Conserved in Variable Time? All real systems (macro and micro) experience time dilation."

[@DavidFMayerPhD]

You are the ONLY person I have found on the Internet who CORRECTLY explains Conservation of Energy and Wave Function Collapse. Kudos to you.

[@Blox117]

you conserve energy by turning off the lights, and waves collapse on the beach. gosh its not like this stuff is difficult!

[@Warlord_Megatron]

@@Blox117 thanks lord blox for this knowledge.

[@Warlord_Megatron]

@@Blox117 my lord, can you explain me that where all the energy which is present in our universe came from? Maybe big bang but where did big bang get it from?

[@kiraPh1234k]

@@Warlord_Megatron What a strange question to ask someone who just made a joke. Is that normal for you? You hear a joke and then ask the comedian a question nobody has been able to answer yet?

[@TheCollectiveHexagon]

@@Warlord_Megatron Thats the thing: its always been here the only thing that change is its location and distribution

[@IllogicalMachine]

"Potential energy is stored in the balls." -Particle Physicists

[@glory6998]

😂😂😂😂😂

[@wasoncethr7565]

😂😂😂

[@seven-qpitt2176]

Masterful! 🤣🤣🤷🏽‍♂️😎

[@karmiclaugh]

You mean the tustecuts😂😂😂

[@karmiclaugh]

You know what i mean

[@FLS96]

Weird how this is still widely regarded as an exact law of physics, altrough it is known to not hold for a long time. Another one is the 2nd law of thermodynamics: there's an extremely small, but non-zero probability for entropy to decrease in an isolated system.

[@ScienceAsylum]

Most people don't need to know about this long-time exception, so it's often just easier to lie about it to emphasize the importance of the principle. A lot of the time, successful teaching is knowing exactly how much to lie.

[@ralfbaechle]

Let's not forget how quantum theory shakes it left and right as well. That said, for most applications treating energy anything other than conserved is very pedantic and totally unhelpful. I'm sure NASA hasn't even thought about it when sending space probes to the wastelands of the outer solar system. That said, while Noether's Theorem makes a big dent into the holy priciple of the concervation of energy, the concervation of energy for a long time indeed has been a holy foundation of physics like so many other asumptions. Newtonian physics was improved by the relativity. Atoms once were considered indivisible, then electrons and the nucleus were discovered, it was discovered that the nucleus is made from two types of particles which eventually again were discovered to be composed from yet smaller bits and pieces. Like so many principles one should keep in mind that they're helpful shorthands that hold up when looking at things from a certain distance but fail close scrutiny.

[@winniepooh4130]

@@ralfbaechle If I remember correctly then in the vacuum of space or where (I don't remember exactly if it's some dimension or what but obviously in this universe) energy is actually being created but it's of lowest potential so that's why we can't extract it. The zero point energy if I recall correctly.

[@suryanarayan2032]

Yes, in an isolated system. Doesn't the second law state that net entropy always increases?

[@ecicce6749]

@@suryanarayan2032 it says "tends" to increase. I think Brownian motion or the Brownian Ratchet shows it's not really a law but just an observation of the most common case.

[@randomisedrandomness]

Ooooohh, so that's why squirrels in my park explode...

[@_Arminius]

Indeed, so there might be truth in that old wives tale that Lemmings explode too... 🤔

[@ScienceAsylum]

@@_Arminius I used to have the old Lemmings game. I like puzzle solving games.

[@henrymarckisotto9025]

This is hilarious thank you. And I totally pictured lemmings too lol I miss that game they should make a new phone version. A good one

[@mal2ksc]

Nah, there's just a shortage of whale carcasses to explode and _they_ need to stay in practice. 💥

[@gustavgnoettgen]

@@ScienceAsylum "UUEEH!" * *SPLAT!*

[@mrudulvemuri182]

Somebody said "We imagine that the universe is strange. But, in reality the universe is stranger than we can imagine." The universe is under no obligation to make sense to us.

[@mrhatman675]

It s like everytime the universe evolves and new laws exist wtf

[@mrhatman675]

I bet there s going to be a new form of physics that says everything in relativity and quantum mechanics is partially false in the certain extreme circumstances

[@namidawhamida5958]

@@mrhatman675 you are already correct

[@jaredgarbo3679]

@@mrhatman675 You are right.

[@mrhatman675]

@@namidawhamida5958 what happened?

[@ibanix2]

PETA called, they're asking about your non-conservation of squirrels But seriously, great episode

[@BainesMkII]

Maybe it is just a really defective clone, and not a squirrel at all.

[@jamestheotherone742]

@@BainesMkII #defectiveclonelivesmatter

[@adeshpoz1167]

@@jamestheotherone742 hahaha

[@Warlord_Megatron]

@@jamestheotherone742 lmao

[@vinnyhorapeti2461]

@@Warlord_Megatron please watch gary yourofsky's speech on veganism on KZbin please and end animal cruelty also check out earthling Ed, Dr neil Barnard, mic the vegan , Dr michel greger and joey carbstrong for more info and insight 😇💚

[@planckvanilla8997]

03:05 I love how it shows the earth burning a 100 years from now.

[@otakuribo]

You have a gift for turning complex physics math salad into intuitive concepts with these animations; like the energy bar changing over time to show where the energy is but that the overall amount of energy you're looking at is still the same.

[@raphaelalcantara3248]

This ist the only channel in YT that I watched every single episode, best science channel!

[@SaberTooth2251]

I really like seeing videos that call back on previous videos to allow for a complex subject to effectively be communicated in a quick video.

[@SilverAlex92]

wow the thumbnail was genious! I always loved your conservation of energy running gag, so this ep feels like a conclusion to a plot line that you have been setting for some years. Also its good to see some love for Noether, she was a true maths and psychics badass

[@brandonklein1]

*physics

[@nokian9005]

I just want to say that you're on the same level to me as "physics videos by eugene khutoryansky". Both you and Eugene do a fantastic job at teaching difficult subjects and making abstract AF concepts actually "click" and finally make sense. I've never had as many "eureka I finally understand this" moments from the same creator as I've had from watching your videos. If Richard Feynman was alive and had a KZbin account, I'm sure that he would have been a great fan of your content. Keep up the great work. The world needs more videos like yours.

[@ScienceAsylum]

Thanks! 🤓 It's always nice to hear that my work helps people understand.

[@Warlord_Megatron]

I agree.

[@LookingGlassUniverse]

Wow, amazing video Nick! I didn't know that! Super interesting :)

[@ScienceAsylum]

Thanks Mithuna!

[@bucke9228]

I lose my conservation of energy every morning when I wake up.

[@TheCimbrianBull]

Relatable!

[@ScienceAsylum]

😂

[@robertsparkman8516]

Coffeeeeeeeeeeee!!!!!!!!!

[@ScientificReview]

Dark energy sucks your energy to expand the universe 😁

[@radix4801]

Coffee energy is transformed into brain energy.

[@alexanderalden3318]

I died at “conservation of energy is sometimes violated”

[@karabomothupi9759]

One of the best physics channels. Up there with PBS Space-time

[@TheChrasse]

@@Neoprototype That channel might just be aimed for just a bit more knowledgeable audience. Doesn't make it a bad channel.

[@mask3dal3xx]

patrick henry Why? It is not crap.

[@seangeiger45]

@@Neoprototype I'm not sure you've ever even watched PBS Space Time, because Matt goes into great detail explaining the concepts (sometimes too much). Just because it may not be a style that you enjoy doesn't mean he's not explaining.

[@Tore_Lund]

@@TheChrasse Sometimes you can just hang on with the tip of your fingernails, other episodes of PBS spacetime are for 5'th year theoretical physicists that read up on obscure 1800' theories in their sparetime.

[@lyrimetacurl0]

At least PBS Space Time doesn't think conservation of energy can be violated.

[@rekhamishra9208]

I love it when he says "Conservation of energy shall not be violated", but this video made me think, like crazy, hope you keep this up.

[@bdpc-dk2xb]

Been a fan for years, glad to see the channel is steadily growing, but it's a fricken crime this isn't the number one science channel on youtube.

[@herbie909]

I never thought about those two exceptions changing the actual quantity of energy in the universe, but that seems obvious now. Thank you for pointing that out! Your videos are a joy to watch as well as informative.

[@bhaswatidasgupta8055]

I just wanted to say thank you. 😊 Because every time I watch your videos I fall in love with Physics, Mathematics and this Universe..... Wonderful and Informative videos. Keep up this great work.

[@ScienceAsylum]

That's wonderful!

[@yadav-r]

Not a Physics student, you explain things so clearly & in such a digestible way, I enjoy watching it. even though I might not use that in a professional capacity. Great to find your channel. Good Day.

[@jensphiliphohmann1876]

About 02:40: I learned it differently: Any (continuous) symmetry of _action_ leads to a conserved quantity. This is not the same because it's both a one-way implication. NOETHERs theorem, as I learned it, means that you might have a conserved quantity without a symmetry of acton behind it but not the other way: If a quantity's conservation is violated, the underlying symmetry must also be so.

[@5pecular]

In the beggining God said Let there be light, then light redshifted

[@PabloEscobar-gu8sd]

My God that was a nerdy jokes

[@user-vg7zv5us5r]

What do you do with your life?

[@stefansauvageonwhat-a-twis1369]

@@user-vg7zv5us5r make people laugh apparently

[@natealbatros3848]

I've thought a couple days ago about that, it seemed unreasonable that the universe is expanding but the amount of energy stays the same. by the way, love this channel youre making science understandable for everyone.

[@globaldigitaldirectsubsidi4493]

You really make it understandable. An ethical channel!

[@Zubzub343]

Really love your channel. Especially the fact that you try to go a bit beyond what usual popularization physics channels do while staying simple ! Keep going through "untold" subjects :)

[@MattMcIrvin]

I like this guy, he includes all the caveats and edge cases. And this is one. It's possible to stick an extra term for spacetime into the energy density of the universe such that it's still conserved. But that quantity is dependent on the coordinate system you choose. In other words, it's not a thing, not physical, just a bookkeeping contrivance. If I recall correctly, this whole issue really hung up Einstein when he was developing general relativity. He felt there ought to be a conserved contribution to his energy-momentum tensor for spacetime itself. But he couldn't do it in a coordinate-independent way and he eventually just gave up on it, which let him move forward. Not long after, Emmy Noether clarified what the trouble was.

[@rajatkarmakar4586]

Great video as always. I would like to mention another situation. During Meson exchange inside atomic nucleus conservation of energy is violated all the time. Heisenberg's uncertainty principle ∆E∆t>h/(4π) allows it. In this case ∆E∆t

[@vikashkotteeswaran700]

you are just awesome sir!!! before seeing this video i thought that there wouldn't be any source of 'noether's theorem and conservation of energy in large scale' that suits me, but this video gave a great outlook on the concept. I think u must release a book on some concepts which are not familiar and not explained well or which are of inadequate of sources that suits people like us

[@alexandertownsend3291]

He wrote a physics book. Check it out.

[@RobinPillage.]

YDT is the man! (or lady, not sure which😊) And as usual great video. This is one of the best channels by far. Not to mention important. imo

[@monkbunk1396]

"Conservation of energy shell not be violated!" Gets funnier every time.😆

[@ABC-cr9mi]

I honestly don't how your channel only has 152k subs, you deserve millions, I guess you just need a video to go viral to get the exposure. good luck

[@anderstopansson]

The majority of people(like 85%) is not the clever one. Everyone subscribe to what they understand or what´s trendy on main stream media... Good luck with the elections!

[@Lucky10279]

I asked a question about this topic online and I was quite surprised at how many physics literate people didn't know about this exception to energy conservation. I'm not surprised the average person doesn't know about it, but I thought most physicists would. On the bright side, I've already linked to this video twice in response to people who didn't know about. Hopefully you'll get some new subscribers.

[@Warlord_Megatron]

But I didn't get that where did universe get it's energy from? From the big bang? But then where did big bang get the energy from?

[@Lucky10279]

@@Warlord_Megatron We don't know.

[@InssiAjaton]

Just as you stated at least twice, the variations on our everyday life are so tiny that we might as well just ignore them. Which is good, because so many of my required calculations during my studies depended on the principle of energy being conserved. Otherwise, I probably would not have got my degree.

[@Mathieu_Matheow_Benoit]

I know what is NOT conserved...my previous physics knowledge...AGAIN 😫😬

[@glory6998]

😂😂😂😂😂

[@fidelio6311]

I told this to my friend. He may think I am crazy now. i guess I'm in the right place :)

[@TheOtakuPrince]

Dont worry. Your not alone. Actually I cannot believe it. If the first rule of thermodynamics fails on the cosmic level then something is wrong.

[@dankuchar6821]

Energy is always conserved! Expanding universe, "Hold my beer." Conservation of energy works for closed systems. An expanding universe is NOT a closed system. It's that simple. I think. 👍

[@snekwrek5454]

It is, no energy is added from the environment, infact there is no observable and as far as we know, intractable environment, so it's a bit more complicated than that.

[@neil2444]

Maybe what we think of as dark energy is merely energy and matter existing in parallel universes. Point in favor for many-worlds interpretation of quantum theory?

[@pawemarsza9515]

@@neil2444 it makes no sense, at all. Why, and how, would parallel universes interacted with ours, and why in a way that they transform energy from their universe to ours, and in a very specific way, that it is spread evenly in the whole space

[@neil2444]

@@pawemarsza9515 How does dark energy interact with us at all? It's just a theory, and it makes as much sense as claiming 80% of all energy just exists, despite not having any proof of said energy. My point was just that if positioning of particles is a probability wave function, then finding that particle in its most probable spot is just a sliver of that entire probability wave function. Maybe the universe is the whole probability wave function, not just the sliver where you find the particles.

[@patrickfrank7397]

@The Science Asylum What makes you so sure that the energy gain from dark energy is not compensated by an energy loss in other (potentially unknown) quantum fields?

[@nibblrrr7124]

The energy in those hypothetical fields would still count towards the total energy density in the Friedman equations that describe the expansion of space. So AFAIU then there would be no accelerating expansion we could observe, and thus no need to postulate dark energy in the first place. Plus, y'know, the complete lack of evidence or theoretical necessity for any such field. :^)

[@justdave9610]

If it's balanced by an energy loss that would be gravitational potential energy which is a negative number but I'm not smart enough to know if this even comes close to balancing out

[@Johncornwell103]

Dark Energy makes up 70% of all known energy/mass in the observable universe. That quantum field you postulate would probably already be discovered by now.

[@unname8486]

Isn't 1:40 incorrect. There should be some kinetic energy left at the top, because a squirrel still has horizontal velocity.

[@ScienceAsylum]

CRAP! No matter how much I double and triple check things, there's always a mistake. I'll pin a comment.

[@billjensen401]

Great catch!

[@Mckeycee]

finally thank you for clearing this up I have been wondering about this for a while

[@ScienceAsylum]

You're very welcome :-)

[@gaeb-hd4lf]

Underrated channel for sure...

[@samuelowens000]

I literally found this channel this week, and have binge watched the whole thing. I think I may have gone a little crazy 🤪 (but that's OK 😆)

[@ScienceAsylum]

I'm glad you're enjoying my work 🤪

[@Odskee]

Love finding a new science channel to binge watch - amazing stuff, thank you!

[@paulvale2985]

Yet again elegantly explained. Thanks. Best science vids on YT.

[@flannn6]

OMG! He made an entire video about it! ahahaha so funny! It seems like whenever we get closer to fully understand something the universe somehow blow it away. xD

[@felipemldias]

This channel deserves many more subscribers

[@Kapomafioso]

If the "energy" is not conserved, I don't know what quantity we're actually talking about. Let me clarify; as you already mention Noether's theorem - if there's time translational symmetry, you can DERIVE what the corresponding conserved quantity is and slap the name "energy" on it. However, if there isn't time translational symmetry, you don't have such a quantity, so what do you call "energy"? To me this is like saying "my car is red" and my friend says "I don't have a car, so it is not red" - but how can he say what properties "his car" has or has not, if it does not exist? To me it doesn't make sense to say my car is or isn't red if it doesn't exist in the first place. Same with energy - if it can't be defined, I don't like to say "it" is not conserved. The only way out I can think of is calling Hamiltonian "energy". If the system described by a particular Hamiltonian is time-invariant, then the Hamiltonian itself turns out to be the conserved quantity, so I guess we can call it "energy" even in cases when it explicitly depends on time.

[@anonkiddo]

I'm so glad I found this channel, already subscribed!!

[@robertschlesinger1342]

Excellent video and well worth multiple viewings for students.

[@tedarcher9120]

Isn't CMB just spread around the universe and red shifted, like light leaving from close to a black hole?

[@ScienceAsylum]

Yes, it's more spread out, but that's not why it's losing energy. There's still the same number of photons, but now they're all at a lower frequency. That means the _total energy all together_ has gone down.

[@tedarcher9120]

@@ScienceAsylum yeah, but photons leaving a gravity well also loose energy due to red shift. Does the conservation principle break there also?

[@locutusdborg126]

@@tedarcher9120 Yes, you are correct I think.

[@leobidussi5039]

For Black Holes the situation is a little bit more complicated. The question is always the same: does the system photon-black hole has time traslation invariance? If and only if the answer is yes, than the TOTAL energy is conserved. For the most archetipical black hole, the Schwarzshield one, it is true and the total energy of the photon is conserved. But a gravitational red-shift is indeed present, as the photon travels away from the BH, it appears to red-shift, and the energy measured by different observers is different. This is because, loosely speaking, the photon acquires gravitational potential energy relative to the BH as it goes far away. The concept of gravitational potential energy is usually ill-defined in General Relativity, but for some BHs it can be a useful concept and it is not cheating, we have that the total energy is conserved, it is just that it differs from the energy that different observers measure. For the cosmological red-shift the story is different, the object that defines distances in GR, the metric, changes with time, hence we have no time traslation invariance and the photon's energy dilutes away as it travels through an expanding universe, energy is truly lost.

[@tedarcher9120]

@@leobidussi5039 photons don't have mass, so they can't have potential energy. Red shift is happening when photon is travelling from more compacted space near black hole into less compacted, and thus redshifts. Literally the same thing happens with cmb, but the whole universe

[@TheyCallMeNewb]

So generous a patron supporting the obviously worthy Asylum. I hope to follow the example post-university!

[@geekjokes8458]

This is actually the first good explanation for this on youtube

[@kbbeats3099]

I'm fond of your explanation of energy. So many people are using that word incorrectly, or have incorrect ideas about what energy is. Great work, Nick.

[@localverse]

What is his explanation of energy? (i.e. what's the correct explanation)

[@Kislay11]

@@localverse he has a video about what is energy, you may watch it, its great too

[@deltabeta5527]

@@Kislay11 that video was the reason how I discovered this awesome channel on KZbin

[@ScienceAsylum]

@@localverse What the HECK is Energy? kzbin.info/www/bejne/qZ_NYqp4qdNpf5o

[@kbbeats3099]

@@ScienceAsylum Precisely the video I'm referencing. As eloquently/simply explained as I've ever seen.

[@SirWussiePants]

Question: if the CMB is shifted to lower energy due to the expansion of the universe - isn't that energy just spread out over more space making the sum of the energy the same across the universe, but less only locally?

[@ScienceAsylum]

The total across the universe is _also_ less.

[@consciousenergies]

Love your videos! I do think its important to state a theory when it arrives in our conversations. Dark Energy is still a theoretical postulate to fill a space of physics we don't understand isn't it? The CMB is also our best theory and has yet to be proven as anything other than the furthest we can "see" in our 4D understanding of the universe. In all tests of the 1st law of thermodynamics, conservation of energy prevails true experimentally. Keep up the great videos and I appreciate all the time you put into explaining complex topics simply.

[@haddow777]

I've had questions about this for a while. In another video, someone showed that Planck's constant is used in the measurement of energy in a photon. This makes sense that the smallest indivisible unit of measure for distance is used to measure the smallest indivisible unit of electromagnetic radiation, the photon. How though, does the universe expand the fabric of spacetime? The two possible methods I can see is, either it just gets larger, inflating through increasing the size of Planck's constant. You increase the constant, and everything gets larger, stretched out. The other way, is new space is added somehow. Some some portion of space has a specific number of Planck measurements and then it has one more than it used to. So, space expands at the fundamental level by increasing its dimensions, thus adding to its ruler. Basically, at one time you had thirty skittles in a row, then over time you have 31. Over time, new skittles get added, increasing the total. In this scenario, couldn't it be that as a photon is traveling through space, this expansion stretches the photon, adding space to it too? In this event, the photon stretches past the indivisible size of a single photon and divides into two photons. In this way, the energy, thus the frequency, is divided amongst the photons. Each contains carries a lower frequency, divided from the total original frequency. Thus, the energy is divided up amongst the photons and not lost. That makes more sense to me than so much energy just going out of existence.

[@constpegasus]

Best science videos on KZbin.

[@lonneke1725]

awesome vid as usual! I found your channel last week and binge watched all your videos! I have a request - i'd like to see more quantum mechanics/theory videos. I've been wondering about quantum particles and how QFT relates to the larger macro world. thx!

[@ScienceAsylum]

Working on it :-)

[@James42_]

Wait so everything gonna disappear over time (if every mass turned in to light and no black hole )?

[@addajjalsonofallah6217]

Yup

[@locutusdborg126]

And since we are in a simulated universe, we will eventually pixilate and disappear.

[@leobidussi5039]

Only the energy of photons is lost as they travel through an expanding universe. Massive particles retain their energy and experience no cosmological red-shift. Whether or not matter itself will decay away on cosmological scales is a question for the Standard Model of particle physics, as far as General Relativity is concerned they are not affected at all.

[@cleitonoliveira932]

Basically we are not allowed to travel beyond the local group of galaxies because of the expansion. The rate is so high that it's higher than the gravity pull, the groups will escape from each other and accelerate above the speed of light.

[@martiddy]

Yeah, is called "Heat Death of the Universe". And it will happen at the end of the Dark Era of the universe (which will be around 10^1000 years from now)

[@SpiritmanProductions]

Great video, but I'm confused by one thing: Why isn't the dark energy density simply decreasing?

[@julien5053]

We don't know what it is and where it comes from. Maybe the ernergy could be conserved if we could mesure the transfer of ernergy into dark energy. (highly speculative, because we don't know)

[@lezhilo772]

Dark energy is an extra term in Einstein's field equation(how matter curves spacetime), so it may seem that physicists can just add whatever term into the equation to explain anything. But there are certain principles that these extra terms have to obey, and these principles imply that the dark energy density must be constant. Specifically, a non-constant dark energy density violates the local energy momentum conservation condition, which is still true in GR. It is the global conservation of energy(adding up all the energy/momentum in a finite region) that is violated.

[@SpiritmanProductions]

@@lezhilo772 Makes sense.

[@raduarghiros7364]

@@lezhilo772 since we don't really know what dark energy is, maybe we are missing something here.

[@lezhilo772]

@@raduarghiros7364 Yep you are right. This is what our current theories say, but it is entirely possible that they will be proven wrong in the future.

[@scotthansen1442]

Finally, someone who can intelligently explain that there isn't truly conservation of energy. I used to say that conservation of energy was a bunch of bunk when I was in school because they kept adding/redefining energy until it was once again conserved. Hopefully, now that we have the better understanding of dark energy, we will let go of that archaic principle which was declared. Dark energy disproves the conservation as you said. Let the thought of conservation go.

[@narfwhals7843]

There is conservation of energy in a time invariant system. Its just that the universe isn't one. Conservation of energy shall not be violated* stands. *terms and conditions may apply

[@antoniomaglione4101]

The possibility of experiencing a lapse of the conservation of energy is the same of experiencing time dilation because of relativistic speeds. It is mostly of use for theoretical physicists, nonetheless extremely important for everyday science. Two notes. In the physics books I used to study, 40 years ago, the "Universe is lazy" thingie was described as "Principle of minimum energy". I won't loose the occasion to appreciate Emmy Noether intuition and extreme intelligence, in seeing the necessity for a form of simmetry at the base of energy conservation and transfer. Thanks for the video...

[@thevigilantone5902]

Very interesting, I was just wondering and I couldn't how energy is always conservating if we have this issue of dark energy and CMB, Thank you, You explained it in a very fun and understandable way.

[@ScienceAsylum]

Happy to help 🤓

[@thevigilantone5902]

@@ScienceAsylum love your videos. They fun and informative at the same time❤️

[@crouchingtigerhiddenadam1352]

Conservation of Information shall not be violated! Its good to see you plug your book again. It's a very useful book. Whatever next, posters?! 😀

[@ScienceAsylum]

I'd love to make that types of energy chart into a poster, but it needs to look cooler. I need to talk to my graphic design friends.

[@hebruixe9125]

I love how your clone bows his head in shame every time you answer his question. LMAO

[@jlpsinde]

Great video, as always! Man you deserve more subscribers! Ly

[@TunaAlert]

A few days ago the question of where the energy of the CMB goes as it gets redshifted by expanding space has popped into my mind, so thank you for answering that!

[@saumitrachakravarty]

This video was a long time due. Every time you uttered your conservation of energy mantra I screamed Noether's theorem internally.

[@tommywhite3545]

Haha 🙂. But mostly WOW and Woh .. and 🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔 so, hmm .. but it is unclear where this dark energy (vacuum energy) comes from? And to truly understand this I guess I need to go study Noether's theorem and Lagrangian mechanics (more) and pff you mentioned some terms and equations I never even heard from .. so could you give me some advice? One of your best imo 👍!!

[@mask3dal3xx]

Can dark energy theoretically be harvested? Like by connecting two very distant part of the universe with elastic ropes? What would the power output of such a system be?

[@nibblrrr7124]

AFAIU no, because putting energy which is already equally distributed (in equilibrium) to work would decrease entropy, and therefore violate the second law of thermodynamics. (Kinda like the hot high-pressure gas in a combustion chamber has lots of energy, but it will not expand & make the piston move one bit if it's just as hot & dense outside of the piston. PBS Space Time did an episode on zero-point energy.) The huge rubber rope is a nice thought experiment, and I haven't figured out yet why it wouldn't work. :^)

[@martiddy]

I don't think dark energy works that way

[@nibblrrr7124]

As for the power: Dark energy is spread around incredibly thinly, with a constant density of a couple *nanojoules per cubic meter.* That should be an upper bound, and it's not a lot. Not sure how that would translate to power per length of rope (disregarding that it can't work b/c thermodynamics), but only using 1 dimension of the 3 expanding ones probably doesn't help? ^^ * It only makes up ~70% of the universe's total, because the universe is mostly empty space with barely any matter (dark or regular), but just as much dark energy per volume

[@mask3dal3xx]

nibblrrr I watched that video on PBS Space Time too and I understand what you mean but I think my design is fundamentally different from that piston. It might not work because of locality though.

[@mask3dal3xx]

nibblrrr Why would my system violate the second law of thermodynamics?

[@bardrick4220]

It's good to talk about the exceptions . . . there's more, but we're not allowed to talk about them because of dogma . . . Remember that the universe is under no obligation to behave the way we want it to!

[@Chad_Thundercock]

3:04 I appreciate what you did there.

[@Anamnesia]

Damn! You should have been reclining on a chair & doing from a beer bottle (or perhaps a test tube?) when you said, "Boy, that escalated quickly..."

[@ScienceAsylum]

😂

[@thassalantekreskel5742]

Opinion: The CMB's "loss" is accounted for by the expansion of the universe. There isn't less energy, it's less energy density because the same energy is stretched over more space. In fact, with the right equations and precise measurements, we should be able to calculate exactly how much the universe has expanded from the moment the CMB was emitted. As for dark energy, there are plenty of folks in the scientific community who are less than convinced that it's even real. New models of physics are being developed that do away with dark matter and dark energy, and are showing great promise in being just as useful, or even more so, in predicting galactic movement and the formation of the universe as we see it today.

[@mohammadqasem4060]

I don't think we should redefine energy we can consider these events as special cases

[@snolahc]

Special cases don't exist. Either energy is conserved and we don't understand what the expansion of space-time is, or we don't understand what energy is.

[@sorry6726]

This make us more eager to find what dark energy actually is

[@mohammadqasem4060]

Sure dark energy will be as a key for a lot of questions

[@EngenhariaHardcore]

Like you said, it depends on the timescale you are investigating. If it is a humanly realizable timescale (from fractions of seconds to hundreds of years) then we can just stick ti the energy concept we already have and it will all be fine. In you are investigating cosmic events, like the big bang for example, then the corrected concept of energy could be more appropriate.

[@ScienceAsylum]

Fair.

[@Roonasaur]

Fun fact about squirrels: They are one of only a few animals that can survive a fall from any height. They can spread themselves out enough that their terminal velocity results in an impact that they can handle.

[@simplicitas5113]

Using combinatorics and the statistical mechanics interpretation of entropy, I predicted the breakdown of the 1st or 2nd law in an asymmetrical universe when you add the cosmological constant. And now I found this video. Wow. I feel like a genius.

[@Hexcede]

What do you think about this? If you say energy must have a constant rate of change per unit time, you solve everything super nicely. Energy by definition only means something *over time*, because really, what you care about is *not* conservation of *energy*, but actually conservation of *work*, which is just the transfornation or "consumption" of energy over time. You can gain energy, but you can't gain work. You can then redefine the cosmological constant not as the rate of change of the expansion of space, but instead as a rate of how quickly time slows at a given velocity. This is scarily similar to the thought experiment of how light speed travel would effect your perception of time relative to other objects. The expansion of space is by definition absolute and goes against the core of relativity, but the slow of time by an amount proportional to speed is relative and produces the same perception, or others which differ by the relative speed of an object. If it takes longer to reach a destination, it is perceived to be further, but that does not mean it is, just like traveling towards or away from galaxies causes the light to shift, which you could potentially explain as the exact same phenomenon, as relative movement to the light we perceive slowing or speeding the passage of time. That would imply that light red shifts as it travels not because the space it travels through is growing, but because our perception of how much time has passed for the light to arrive has grown from a strictly linear amount. In other words, time can be thought of as a rate of change of velocity as much as velocity can be thought of as a rate of change of time, they are both equal quantities by this definition.

[@anatheistsopinion9974]

5:14 That sound effect cracks me up every time XD

[@mal2ksc]

I didn't even realize it wasn't part of the background music track, since it's right in key and all.

[@diggerpete9334]

I don't get it.

[@benjaminbrady2385]

I felt pretty flattered the other day when my brother (who is in the last year of his physics degree) asked me for help in understanding the quintessence of dark energy, even though I am merely a 17 year old who reads Wikipedia articles and the linked papers at the bottom. Just felt like saying that this channel is where my interest in everything physics started, ha. Thank you Nick, you will always inspire younger scientists!

[@bdpc-dk2xb]

I welcome my new Warden YDT, you the real MVP

[@sanikadixit9223]

I like the way you always use a squirrel. It is pretty unique.

[@alyasker2194]

*Sees science asylum notification* IMMEDIATELY CLICKS

[@LiLi-or2gm]

Thank you for at least giving Emmy Noether a bit of respect and acknowledgement. Too often, the women in science are overlooked. Ms. Noether is sadly, barely known as the person of outstanding intelligence, work, and accomplishments. Comment readers: please take a few minutes to take a look at all she did: en.wikipedia.org/wiki/Emmy_Noether#Contributions_to_mathematics_and_physics

[@ScienceAsylum]

She was a big deal.

[@mask3dal3xx]

List of things that violate conservation of energy: -Cats -Toddlers -Human stubbornness -Politics -Naked Bart Simpson swinging on clothes line

[@kyedo]

okay so lets see if I can untangle space-times definition. First lets observe planck space, Now, forgiving any punctuation; The rule on the conservation of energy states this: All of the planck spaces of the filled(occupied) region of the universe must a. contain some energy at all times(virtual particles, photons, etc...) b. The planck space must conform to the geometry of lets say a photon, while the photon (particle, local wave function) occupies that space, on a relativistic scale this distortion is matter ie. and gravities interaction. Time is the total amount of entropy that takes place in a closed system as all closed systems become chaotic, and an expression indexable as the total descriptor value or wave funcion of the complete system.

[@DonDee123]

"The net sum of energy of the universe might be zero." (Leonard Susskind) "The universe is a free lunch." (Michio Kaku) So if the increased distance of matter over time due to dark energy increases the negative potential gravitational energy (don't ask me how that is supposed to work because from my understanding of classical physics gravitational potential energy is positive), the total energy of the universe is still conserved.

[@conscious_being]

As galaxies move away from each other, the negative gravitational potential energy _decreases_ i.e energy of the universe increases. That by itself would have been sufficient to prove energy is _not_ conserved at a Cosmic scale, if the expansion had not been slowing down (i.e no loss in "kinetic energy" of galaxies). But accelerating expansion, coupled with increasing dark energy simply makes it impossible for energy to be conserved on a Cosmic scale.

[@DonDee123]

@@conscious_being I would completely agree with you. But bigger physics brains than ours say it's different...

[@conscious_being]

@@DonDee123 The math is the same whatever the size of the brain. Unless someone can _demonstrate _ how that is so, one has no reason to believe them. Science is not based on faith in authority. The biggest fraud of them all is the claim that the net energy of the universe is zero, the negative gravitational energy cancelling out the positive mass energy. Let alone the fact that the latter is several orders of magnitude higher than the former, if that claim were true, matter should spontaneously appear everywhere without violating energy conservation law. Sometimes I wonder if these science popularisers are running a psy-op testing the gullibility of the audience.

[@joshuacoppersmith]

My two cents: We're missing something about Hubble expansion and dark energy...something big. Once we get it, we'll see that Noether still applies. Point is, we've got to stay humble if we're going to be crazy.

[@photelegy]

6:26 Ahh, he looks so sad 😥

[@jamestheotherone742]

"Dark energy" is a kludge to plug the errors in our cosmological models and physics. Noether's Theorem points out this paradox. Energy is always conserved, its our maths that are wrong.

[@sorry6726]

U didn't get point

[@jamestheotherone742]

@@sorry6726 I did. I disagree with the premise. Apparently you didn't get my point.

[@nibblrrr7124]

You're begging the question by just assuming energy conservation. In a sense, Noether's theorem explains "why" conservation laws exist: symmetries. If a symmetry is broken, why should its conservation law still hold? Time translation symmetry is already broken in most solutions of general relativity. The accelerating expansion* of the universe is just empirical confirmation that it's actually broken in our universe, assuming GR. So to "save" energy conservation (again, why?), you would need to "sacrifice" not just LamdaCDM or anything fancy cosmologists have come up with to try to fit the data, but GR itself (which has passed every other empirical test and is derived from sound theoretical principles) - without any replacement theory in sight. * (AFAIU even anything but a perfectly static universe that doesn't expand or contract at all would violate TTS and therefore energy conservation)

[@jamestheotherone742]

@@nibblrrr7124 Symmetry is maintained by mass energy balance. You trade one for the other, right now as a one way street as with the flow of time. But that is only because we have a myopic view and incomplete understanding of what is actually going on. But it works practically the same way that Newtonian dynamics work for most things. We probably have as good an understanding of the true character of the Universe as Newton did relative to our current comprehension of GR. So imagine how far off we are...

[@red-.-red]

Yeah, scale can be more important than we think when we talk about physics. I remember reading how the laws of thermodynamics break down if the studied system gets too small.

[@ScienceAsylum]

Yep. A lot of thermodynamics is based on statistics in large systems of particles. If the systems aren't large, you can't necessarily make the same judgements.

[@pukkandan]

IMO, this is one of the most beautiful theorems in all of physics

[@ScienceAsylum]

So far reaching, especially in quantum mechanics.

[@lfvkx3929]

It completely depends on gravity ..... Doesn't it??

[@ScienceAsylum]

All spacetime, not just gravity, but yes :-)

[@99bits46]

when you click on a video faster than speed of light

[@ScientificReview]

Tachyonic order.

[@Cashman9111]

NOTHING is faster than light! you big liar....

[@WigantX]

It's plausible, but his finger would be traveling back in time. He would be pushing a different video probably, and losing his finger in the process

[@GTAVictor9128]

@@Cashman9111 Well... Yes and no. It is true that nothing is faster than light in vacuum. However, when light travels through a denser medium like water, it slows down (and bends as a result), so particles like electrons can travel faster than light in water, resulting in the so-called Cherenkov radiation.

[@wasoncethr7565]

By reading the title i am half way baffled but still i will watch the video.

[@dhireshyadav1783]

What I think is that the usual energy-momentum is a form of Space-time, i.e. energy-momentum and Space-time are two different forms of the same thing. To be more specific, energy-momentum doesn't just curve Space-time, energy-momentum "is" Space-time curvature. If one, for example say energy-momentum goes absent, then the other, i.e. Space-time must emerge, so that in total that quantity ("thing") is always conserved. So, energy-momentum (Space-time curvature) can convert to uncurved Space-time and uncurved Space-time (or just Space-time) can convert to curved Space-time. So with the expansion of Space-time, the amount of energy-momentum must be declining. Now, when Space-time stretches (opposite to its curvature), the result is dark-energy, which balances the stretching of Space-time. And hence, the total amount of that quantity is conserved.

[@Binyamin.Tsadik]

1. Dark Energy is not completely understood yet, so energy could still be conserved through some mechanism. 2. CMB energy loss? There are explanations for this, and this could also be due to a lack of current understanding of expansion.

[@kazedcat]

Nope Noether's Theorem means a conserve quantity is a consequence of symmetry or invariance. Conservation of energy is a consequence of time translation invariance. Since we know that time translation is not symmetric this means energy cannot be conserve. You can redefine energy to keep it conserve but that means you also need to redefine time to make it work.

[@Binyamin.Tsadik]

@@kazedcat Great, but Noether's theorem doesn't have to be more true than conservation of energy, also it can remain true because of the increase in entropy. Also the conception of time used for this is false to begin with, seeing as the light from the CMB has only moved through space and not through time.

[@kazedcat]

@@Binyamin.Tsadik Noether's Theorem is a theorem not a theory. Theorem is a mathematical term that is back with formal mathematical proof. Unless Noether included a new axiom outside of standard set theory it will be more solid than any scientific law. To become a theorem it must be logically proven correct unlike theories that just needs experimental verification. If I ask you to show a proof for conservation of energy you will not be able to do it. Scientific Law's are not proven just verified.

[@Binyamin.Tsadik]

@@kazedcat First of all, all science is made of theories. Even "Laws" are based on well established theories. The issue here is that a "Law" is being put against a "Theorem". The first question when encountering any contradiction is to ask "Is there truly a contradiction here?" If there is one, then either one of the two are false, or they are both false. At the moment, I am not certain that there is truly a contradiction, but even if there is one, the theorem could be false. Truth in Physics is Reality itself. Math, Theorems, Theories, Laws, Principles... etc. can all be false when compared to reality.

[@whispersilk]

I clicked so fast I violated conservation of energy at a local scale.