What If Gravity is NOT A Fundamental Force? | Entropic Gravity

[@nobody.of.importance]

Matt O'Dowd is unquestionably a fantastic host, as was his predecessor, but I wanna give a shoutout to those workin behind the scenes, especially the graphics team. Trying to visualize quantum phenomena is an actual exercise in madness, and you guys always make it professional and, at least as far as my tiny brain can understand, pretty good visualizations. The music is chill, mildly spooky, but with a scifi twist, which is spot on for this kind of video. The title cards are always fantastic, and rarely do I see an upload where I think "Iunno, that doesn't sound very interesting." Everyone on your team does a great job, EVEN YOU SUSAN, so keep it up! We appreciate every unit of planck time and body superfluids you guys put into these videos!

[@PlantsAndInsects]

Well said!

[@PedroAbilleira]

100% agreed

[@philharmer198]

There is nothing mad about understanding .

[@nobody.of.importance]

@@philharmer198 True, but I was saying visualizing quantum processes can be incredibly difficult to do well, and they really nail it.

[@philharmer198]

@@nobody.of.importance what did they nail down ? How did they nail it ?

[@kohbaker3394]

6 years ago this channel got me obsessed with physics. About a month ago I started my PhD in gravitational wave instrumentation. Thanks for all the inspiration!

[@Meena-ib5rr]

❤

[@flo0778]

6 years ago this channel got me obsessed with physics, I started to think about it in all my free time. And I started my machine learning degree. Now I have a good wage and I can still dream and discuss fundamental physics.

[@ontoverse]

@@flo0778 savage

[@Reggie-zw8rm]

Six years ago I watched this channel and smoked weed. Six years later I still watch this channel and still smoke weed.

[@Peoplearedumb47]

Just wish he was putting out correct info. He states that time dilation is cause for gravity and speed of light doesn’t have anything to do with light but the speed of causality. He gets some of it but botches more

[@sebastiankalman9097]

This wins 1st place for the number of stops, rewinds and pauses. A thrilling journey - Thank you

[@ninadgadre3934]

Lol seriously i was like a bad record, skipping 30 seconds every 1 minute.

[@jilmarit]

Same here - I usually don’t rewind too much, but here 4-5 times at least.

[@melanieenmats]

Lol indeed same for me :). These videos are brutal. But excellently made imo. I love that they seem to not dumb things down to where it is wrong like in many documentaries. At least that is just my impression cause I can't know. I like this much more than the Neil Degrasse Tyson story-time style.

[@sebastiankalman9097]

Yes. I also prefer this style. Every word counts.@@melanieenmats

[@agrajyadav2951]

you tried at all? Kudos to you man!

[@wolrdsstrongestdrummer]

The algebra connecting entropic force to newtons universal law of gravitation is an absolute masterpiece. I never realized how beautiful math could be

[@Kwauhn.]

13:35 "... although the derivation is a bit much for this episode." Noooo! I need more! Entropic gravity is one of the most interesting subjects Spacetime has covered in recent times! Please cover more!

[@lexidugo]

AGREED

[@lucasvella]

I find it fitting that Newton's gravity was found, because Bekenstein bound is a sort of coordinate trick. I mean, the radius is given in coordinate space, not in the proper space of the stuff actually falling into the black hole. It should be no surprise the results are weird, like the singularity at the event horizon in Schwarzchild coordinates is also weird.

[@Vaporfry]

You have finally crossed the boundary marking the limits of what I can currently understand.

[@Lowenaaa]

yes me too

[@allisonmclay7137]

They get me every week 🙃

[@Salamandra40k]

☝️🤓 "Also when I was 5 years old I figured out the primes from 1 to 100"

[@mrevilducky]

There's no way you understood electron spin

[@CATinBOOTS81]

Maybe also your mind is holographic, maybe if you look at her boundary you'll understand this episode 😁😉

[@roysteves]

Watching the animated algebra as a way of summarizing the path between two versions of the equation is AMAZING. Just a good bit of explanatory visualization, that.

[@shayneweyker]

You can thank the makers of the PBS Mechanical Universe TV series and its sequel for coming up with idea. Graphics were a bit simpler back then though.

[@ultimaIXultima]

It really was! Watching all of that simplified down into something so elegant... Really was impressive!

[@klosnj11]

I want more of that. Animated equations showing how different ideas and theories are linked via mathematics. Glorious!

[@ravengrey6874]

Y’all should watch Animation vs math

[@JimmyCerra]

That’s literally how I visualize algebra in my head when studying math.

[@jajssblue]

Starting from thermodynamics and going to gravity is a really cool idea.

[@IAmJamesTheFirst]

I think you mean it's a really cooling idea.😉

[@jajssblue]

@@IAmJamesTheFirst Glorious physics pun!

[@MichelleHell]

Thermodynamics is the ultimate puppet master.

[@TMmodify]

​@@MichelleHell nurgle confirmed to be the most powerful chaos god

[@TheEduInitiative]

But you are assuming then thermodynamics to be fundamental. You could do the same for gravity and get thermodynamics from it instead.

[@BelgaersTounge]

The animations/visuals of this channel have always been really good, but at this point I would be utterly lost without them. Thank you to the writers and illustrators. Your combined talent almost lets me understand the most bizarre and abstract ideas.

[@Stealth86651]

Man, my favorite youtube channel that i don't actually understand.

[@freakbyte]

I really like how you guys don't shy away from hard-to-wrap-your-head-around topics. Ya'll did a great job of breaking this down into consumable pieces, thanks!

[@manuelcaride7762]

This should be celebrated specially in this 15sec-everything times

[@scottsanford1451]

Agreed! I actually understood most of this. (After watching 30 other "homework" videos). Pure genius. Thanks Dr. Matt!

[@matthiaswolfe9435]

There's the physicists Oppenheim and Oppenheimer, now all we need is an Oppenheimest.

[@happyputt9709]

And beyond the hymen is God. Oppenhymen.

[@AntithesisDCLXVI]

Mirror, mirror, on the wall... Who's the Oppenheimest of them all?

[@DESOUSAB]

Alternatively, Oppenheimerer.

[@smolblacquecat7148]

Not just any old Oppenheimest, *The* Oppenheimest

[@badroad1000]

He's probably friends with actor Tom Hollandest

[@deepblue812]

Having the Newtonian gravity equation just 'drop out' of entopy math really feels like a thread worth pulling

[@thej3799]

I love this kind of stuff because when I was younger we were told that all this would be non intuitive. But now people are finding these things by intuition that feel like they make sense. I'm excited to see what comes out of it.

[@genseek00]

​@@thej3799if you love this type of things, please check out the Kaluza-Klein theory (if you have not already done so). In short, they write the Einstein equations in 4+1 dimensions. Further,they show that if one compacts one of the spatial dimensions, one arrives at the Einstein equations in 3+1 dimensions plus the Maxwell equations in 3+1 dimensions. Thus, the 5D Einstein equations generate the usual 4D Einstein equations along with the usual 4D Maxwell equations. The compact dimension becomes periodic with its period determining the relation between the speed of light and the gravitational constant.

[@das_it_mane]

​@@thej3799it SHOULD BE intuitive. Only reason it's not is because we lack a complete picture

[@asd-wd5bj]

@@das_it_mane Why should it be intuitive? Our intuition is based on our experience, which is inherently tied only to an extremely specific scale, there is no guarantee that the same rules should apply at the universal and subatomic scales as well (and well, it doesn't). Unless you believe in an intelligent designer there really isn't any reason to assume that Not to mention that at the very least the fact that quantum particles are delocalized is rigorously mathematically proven (the opposite fundementally contradicts observations), which is as "unintuitive" as you can get, so why should that "pattern" be present anywhere else

[@AlexGrossman-g8y]

I was flabbergasted when he did that. Truly some compelling links.

[@MaximUsubyan]

I love the direction this series is heading! Please don't stop.

[@tomaikenhead]

Please do the next episode in this series next! It's a challenging viewing experience to have a miniseries like this interrupted by unrelated episodes, because the concepts are complex and it's not always easy to track down the earlier episodes later

[@Strydr8105]

This is the absolute pinnacle of space and time series on KZbin. Although I have to watch it several times to comprehend it. I thoroughly enjoy every episode. Thank you!

[@Julius_Hardware]

Fascinating, I didn't understand any of it. But gravity as an emergent force has a certain elegance to it.

[@paulmichaelfreedman8334]

Curve spacetime , let time pass and you have gravity. The emergence is elegant and simple. Mass curves space, and the curvature tells mass where to move to.

[@dand9244]

emergent gravity is elegant and may help work out some inconsistencies in physics but i wonder if that is all of it. that things bind, coalesce, attract, repel, radiate and are contained or shaped is a consistency between fundamental forces that gravity shares as well. these are things that are not entropic and form unique relationships. i think if you look long enough at the right perspective all the forces - maybe more than just the forces - will appear to be emergent. @@paulmichaelfreedman8334

[@suckmydickthatsrightyousuc1423]

@@paulmichaelfreedman8334 Did you watch the video? It has nothing to do with the curvature of spacetime and stands into direct opposition to the idea that spacetime curvature is where gravity comes from. Who is upvoting this?

[@antonystringfellow5152]

@@paulmichaelfreedman8334 That doesn't explain how/why mass curves spacetime. This video does (or tries to).

[@arctic_haze]

@@antonystringfellow5152 General Relativity certainly explains the *how* question.

[@androsp9105]

'if you allow that entropy to hold you in your seat for a bit' 'No' *floats away*

[@TMmodify]

IN THIS HOUSE WE OBEY THE LAW OF THERMODYNAMICS

[@scalesconfrey5739]

@@TMmodify Oh no, the Entropists are here! Quick, through the escape tunnel!

[@LiftandCoa]

YOU ARE NOT MY DAD you can tell me nothing punk @@TMmodify

[@blizzard1198]

​@@LiftandCoa proceeds to break all fundamental laws of physics.

[@MrTrouserpants101]

@@TMmodify nuh uh

[@vaterchenfrost7481]

it still could be a self circulatory derivation of the end equation. By introducing of Beckenstein-Hawkings corelation for enthropy and gravity one "injects" inderectly the Newtons law of gravity in to the thermodynamical equation.

[@catoleg]

The animation is just perfect, describes exactly what Matt says 10/10

[@olli3686]

You know what was also emergent? Plant walls! They messed up alpha glucose and made beta glucose which was just a flip on one side’s connection, so it became water insoluble and they didn’t have the enzyme to break it down, so their cells pushed these fibers to the edge of their walls. This mutation was just left there.

[@iampixel4086]

Yeah, when I found out that cellulose was just sugar pointed in the "wrong" direction, I was p shocked myself... crazy how small things like that can make a huge difference. We wouldn't have trees if it weren't for that.

[@xyzpdq1122]

That’s for a different PBS channel, Eons 😂

[@Soupy_loopy]

That reminds me of the time I put my shorts on backwards before bed, and I didn't notice until I took them off the next morning. And that one time I wanted juice, but my wife said we don't have any, so I just had go on the rest of the day like maybe it didn't matter if I had juice or not. But I usually don't have juice anyway, so...

[@KatyaAbc575]

Wait what?! That is amazing!

[@SynthwaveDuck]

Plants are really smart. Could have been on purpose.

[@JerBoyd42]

That may be the most satisfying physics derivation I've ever seen. You guys are doing awesome stuff!

[@dcy665]

Please tell Leonardo Scholz that their animations were/are sheer perfection

[@SpaceChimes]

❤

[@4creax]

I don't think I've ever consumed and assimilated as much complex information as I have in the past 16 hours, studying as much as I can about QFT, GR and AdS/CFT. Proud to say I understood pretty much everything on the second watch. Can't wait for next week!

[@MarsStarcruiser]

Nice, lol wish I could say the same but many more rewatches to go for me. Still glad he’s been pushing vids more often than he use to, even though it hasn’t been easy to keep up.

[@tonibat59]

One little problem: If Bekenstein-Hawking formula uses grav theory and thermodynamics to derive the calculation for entropy at the surface (13:09), this means Verlinde is also using gravity (+Thermodynamics, +Q-theory, +Relativiity) to derive ... Gravity ? Voilà

[@XEinstein]

That might perhaps be the little problem indeed. The BIG problem is that we live in normal De Sitter space, which does not have a holographic boundary.

[@morningstarkid07]

The audio quality this episode is way better than it has been lately! Matt sounds like a real person again and not an AI!

[@yyyy-uv3po]

That's what an AI would want you to think.

[@nielskorpel8860]

Well, an AI would look real. To simulate real data is the point of generatie AI. And yes, we will be in the era where that works too well.😢 Reality will be like a dream, and quickly turn to nightmares.

[@Divide_et_lmpera]

Wait... Matt is a real person??

[@VARUNRV007]

Good to see that you have slowed down…I can understand much better now

[@Pratalax]

Putting the bekenstein-hawking formula on a mug and smashing it was a very nice touch!

[@rxscience9214]

I can’t get enough of these videos!! There’s nothing that puts me to sleep like Dr. Matt’s soothing voice and physics I can’t understand.

[@fdwyersd]

@PBS please make him the next host of Cosmos v3.. I think Carl would approve.

[@jojosteel3399]

He's doing just as well a job of it here! Maybe even better

[@fdwyersd]

@@jojosteel3399 agreed... wider audience on tv

[@animalbird9436]

​wider audience in usa aswell😂😂😂@@fdwyersd

[@JJ-fr2ki]

I think Tyson ruined the brand. His portrayal of Newton as ‘the first scientists, rejector of religion and superstition” was HPS malpractice. Gleick’s little bio is called “The Last Alchemist.” Tyson had many unforgivable errors and an irrational confidence in current theories. As well as a gross misunderstanding of scientific methodology which he summarized. This despite me correcting him in person on the later topic over dinner at the Beyond Belief Conference. Also, A. Druyan’s personality is toxic. I say that PBS spacetime and host can stand on their own. They are top notch! And careful.

[@EleneDOM]

@@JJ-fr2ki Wow-- Newton was extremely religious, and that's easy to find out about.....

[@silentwilly2983]

Ever since I learned that gravity is curvature of space (and more or less understand it) I've a hard time to see gravity as a true force, let alone a fundamental force. The entropy approach is new to me, certainly an interesting idea. Would love to see a video about the link with dark matter.

[@SimonBuchanNz]

The *effect* of gravity is due to the curvature of space, but what causes that curvature? All quantum particles are also fields, so if gravity is similar, the gravitational field should also have a gravitational particle, which would mean that it's pretty fundamental.

[@TMmodify]

​@@SimonBuchanNzthe thing that creates the curvature is mass and mass is itself a byproduct of energy that's contained within a system

[@SimonBuchanNz]

@@TMmodify in general we expect there to be something to connect the source and the field: the EM field is caused by electrons, but carried by photons, for example.

[@SimonBuchanNz]

@@TMmodify also, there's the weird detail that we can't directly detect mass, eg in the sense of seeing "mass particles", only infer it via it's effects of inertia and gravity - which is part of why we don't have any theoretical reason why inertial and gravitational mass *have* to be equal (other than not having any reason to think they would be)

[@prich0382]

Gravity is not a force

[@jacksonstarky8288]

Honestly, the more I think about it after watching this, the more the idea makes sense. My academic background is in cognitive science, and the idea of consciousness as an emergent property resulting from the complexity of the brain has stuck with me ever since I encountered it in my first year of university thanks to the work of Daniel Dennett and others. If gravity is something similar, that explains why it disappears at the quantum level; it just doesn't exist at such scales, and can only be perceived at the macro level, just as it ceases to make sense to talk about minds and thoughts at the level of a single neuron or synapse.

[@ignasiusiu]

and what isn’t an emergent property…

[@kylekoschalk7011]

​​DEEZ NUTS EMERGING FROM YO MOUTH! LOL - sorry. ..😂

[@datto2471]

BSc in Neuroscience, engineer now. I've had this thought for more than a few years, really since I learned about neural processing as an undergraduate, not this exact interpretation mind you, but rather our interpretation of the universe could form from a higher or lower dimensional universe which our mind happens to reconstruct in three time and one spatial dimension.

[@AndrewBlucher]

Reading this comment on Easter Friday was particularly amusing. Emergent properties rule!

[@juliavixen176]

​@@datto2471The 3D+1D spacetime coordinate system is because any and all velocities in the entire universe can be uniquely described with only four numbers... Three numbers for space, and one number for time... (Although the distinction between which is which is actually somewhat arbitrary, but you will always have four linearly independent coordinates.) It's... an artifact of describing everything in physics in terms of _motion_ Things moving around -- that's physics! That's literally it... We can't directly measure "time" or "space", we can only measure "things moving" and work backwards to call some parts of that motion "time", and other parts "space". It's a useful mathematical framework and language. You can add more numbers "dimensions", but they don't "go anywhere". All electromagnetic interactions (which includes atoms in solids and light) only needs four, maybe five, numbers: three space-like coordinates, one time-like coordinate, and maybe one more space-like coordinate for electric charge, but the choices are "+1" and "-1" for this extra dimension. Mathematically, you can just keep adding another dimension for every variable in your equation, but these extra variables are not "locations in physical space separated by macroscopic distances which take time to travel across". I forgot the point I was going to make, but even if you add more dimensions for temperature, mass, acceleration, those are all derivatives of 3D+1D velocity. String theories add "dimensions" that are really more like "rotations" of an internal symmetry of a "particle". They don't "go anywhere" any more than how the North and South poles of a magnet can be a "dimension"... It's a number... but not one of the four numbers that describe velocity.

[@johnniefujita]

This is a very provoking idea, whenever 2 different branches merges like that so neatly, usually we find some hidden relation like proposed there. Beautiful work

[@tsm688]

It may be accidentally self-referential... newton may drop out so nicely because some of the inputs depended on newton too. It's still controversial. But damn, what a lovely and elegant idea if true.

[@redandblue1013]

This is by far one of the most fascinating episodes you’ve ever done!

[@beaudweiser]

I have no idea what is going on but I watched it all.

[@byronryan4216]

😂😂😂😂😂😂😂😂😂😂😂

[@Ta2dwitetrash]

Reminds me of an emergent property of mass. Like water is wet only when you have enough.

[@mrptr9013]

Mass *itself* is an emergent property as far as we know, gluons have no mass, but their coupling gives rise to the mass of protons and neutrons. Bosonic mass comes from the interaction with the Higgs field.

[@juliavixen176]

Yeah, "inertial mass" is an emergent property of confined energy.

[@Livlifetaistdeth]

I usually understand some of what he's saying but today...I got nothing. I'm going to have to study up and watch that again

[@nathangamble125]

My understanding of it, simplified: The 3D (or 4D, if you include time) universe might not be physically real or fundamental, but a result of interactions in an real 2D universe, which effectively acts as an "edge" or "boundary" to the 3D universe (even though it isn't a physical edge or boundary in a literal sense, merely a 2D region which describes/encodes the emergent 3D universe, which doesn't actually exist). In other words, we might be living in a simulation, and the real universe is 2D. This is the holographic principle. Gravity can be explained as a result of entropy increasing on this 2D universe, even though gravity seems to result in no net change or a (local) decrease in entropy within our perceived 3D universe. This is currently all hypothetical, but if it makes testable predictions beyond phenomena that are already known to exist, we may be able to find evidence for (or against) it.

[@chelsiec3819]

The stuff making up the hologram clumps (or falls) together so that the hologram projectors (the 2D spherical boundary surrounding the hologram) increases its disorder over time (entropy). That's the best i got after one watch. I've been waiting for this video for about 4 years and it didn't disappoint.

[@pansepot1490]

I prefer Sabine Hossenfelder approach. She doesn’t refrain from saying explicitly that a lot of the esoteric physics theoretical physicists write papers about is as good as pseudoscience when there’s no way of testing it. Other physicists I follow like dr Lincoln of Fermilab or Sean Carroll make a point of explaining clearly what’s established science and what is still speculation. Matt doesn’t.

[@antonystringfellow5152]

You're not the only one!

[@slowfuse]

this video is an April Fools joke is my guess

[@farhadtowfiq6767]

A good step forward to the understanding. The other contradictory step to understanding is how the same entropy is the same as the expansion of the universe.

[@neom0nk]

I see whoever made the visuals on this visited the same DMT space as me. Right on buddy!

[@SpaceChimes]

🌿☕️

[@IIIAnchani]

FINALLY! I've been wanting more mathematical background and I got it. Simply lovely!

[@Saint_Oscar]

I just had a nutty thought. Wouldn't it be weird if the universe is recording information on it's surface depending on the events within it, and that's why it's growing? Like a hard drive that's constantly saving all of the operations of a computer, past and present, and in doing so must grow in size? Weird.

[@MarsStarcruiser]

You just described literally the premise of the “Holographic Universe” hypothesis. It’s mainly in disregard due to the potential lack of any known idea of verifiability, while also within the system.

[@EdwardBlakeley]

Check out Stephen Wolfram and his branchial space stuff

[@gramail2009]

So the more people watch this video and try to get their heads around entropic gravity, the faster the universe expands, right?!

[@PieterPatrick]

I want to thank you for giving Erik some attention. I love his idea of gravity. But it takes a while for understanding it.

[@theastropods]

haven't watched pbs space time in a while, the old intro has such nostalgia. I'm gonna miss it

[@marfmarfalot5193]

Im a Junior in college for theoretical physics and this video made 100% sense and was amazing. Can’t say I would have understood if I wasn’t here but glad to be able to

[@NepzRemix]

This a hood classic

[@nextgenproductions980]

😂😂

[@keithmichael112]

Gravity may not be a fundamental force, but it's still a certified banger

[@Xx_BruhDog_xX]

A hood classic, to be sure, but allegedly not a certified one

[@wmpx34]

Keep…my force’s name…out of your Fing mouth!!!

[@civotamuaz5781]

On crip

[@preppen78]

I enjoyed the trippy Amiga music at the end

[@chriskelvin248]

I’ve always been just as excited about the synth tracks on PBS ST as purposely exposing my brain to ~15 minutes of ionizing radiation that is sitting down for this show.

[@Divide_et_lmpera]

Not sure about Amiga, but the music starting at 14:59 is really trippy. That should be made into a 1-2 hours long track.

[@ChronosTachyon]

I have a hunch that, if the universe is holographic, then the emergent dimension is time, the center is the present, and the boundary is the infinite future. In which case, entropic gravity would be maximizing the final entropy of the end-state universe... and the boundary would have laws explaining correlations, but no actual dynamics.

[@otaku-chan4888]

You call the 'center' the present, but the 'present' doesn't even exist, it's a hallucination of human consciousness. saying the center is the 'past' would make more sense. BUT in that case, what you're calling a holographic universe is just the light cone of the big bang. The light cone of the big bang is our universe, not a single dimension higher or lower... and there goes your theory oops

[@incogniftoar3943]

Like a constant state. No end or beginning, we're just too tiny to grasp the grand.

[@ShaneTheViking]

I've been watching spacetime for years, and have seen every single video up to this one, and have followed along, despite no formal education, and have thoroughly enjoyed this channel's content. Seems like about 3 months ago, your videos stopped being recommended on my feed, and it dawned on me today I haven't seen one in a while. so I searched, and here I am. As I'm watching this one, I'm feeling a bit lost, and I'm going to assume that 3 months of shorts, while sometimes humorous, have blinded me to actual useful, and/or educational content, and have made me, if not dumb, dumber. To combat this going forward, I think I will avoid shorts, perhaps not entirely, dr glaucomflecken deserves an exception, and I'm going to rewatch spacetime content, perhaps from the beginning. Couldn't hurt, revisiting the basics with new understanding is often a good thing, also, I'll get to see power metal stance Matt again. Thank you, Cheers.

[@a176]

to be honest you explained this so well. i have had more difficulty with some of your other episodes than in the combination of this and the previous holographic one. great stuff explaining his theory.

[@joshieecs]

the outro music when he doesn't answer questions is so spooky and threatening

[@Divide_et_lmpera]

You mean the music starting at 14:59 ? That should be made into at least an hour long video with some dark space imagery. Would be a great relax..

[@benmcreynolds8581]

Have you guys covered the research that was done that breaks the concept of relying on Dark matter? It showed the universe might be much older than we once thought. I won't explain the whole thing. It's just fascinating to see a concept that gets around the road block physics has been stuck on for yrs. It's worth looking into it

[@thenullvoidabyss]

Could you provide me some resources for this dark matter, ancient universe theory please my good sir?

[@benmcreynolds8581]

@@thenullvoidabyss let me look. I saw a video of it being covered and I think they have links to the research. It's obviously still a theory being worked on but so has the dark matter theory all these decades.. It was just refreshing to see some members of the scientific community are even getting to the point where they at least thought they should consider going back over certain things to see if certain things maybe got overlooked and maybe that led things to get into this dark matter situation..

[@mixes-level1613]

When an episode references another episode, you should link it in the description! Every time! Because it can be hard or impossible to find!

[@Divide_et_lmpera]

Bloody nerds always need to be told how to do things like normal people!

[@Numba003]

This idea is elegant, but honestly, these last couple of videos have gone over my head a bit. 😅 I hope I'm alive to see our understanding of gravity get a little more concrete one day. Thank you guys for yet another excellent video! God be with you out there, everybody. ✝️ :)

[@quinn_m]

Love this one. It'd be pretty funny if this was all the holographic projection of some quantum file compression.

[@MathMagician93]

Relevant XKCD: 2904 At this point, I firmly believe (and fear) that thermodynamics will turn out to be the unifying theory of everything.

[@Bora_H]

I went looking for that one. Awesome !!! - Thanks!

[@davidwilliams5497]

What about Lagrangians?

[@AndrewBlucher]

​@@davidwilliams5497Reply 1: shh my head hurts enough! Reply 2: They're already emergent. Reply 3: It's never aliens! Flip a coin ...

[@normusdoar]

it wont ever. thermodynamics needs at least one force to explain the moving of its inner constituents. thus, if there is such a force then a Lagrangian will be more fundamental than any thermodynamics equation.

[@CrispyGFX]

What if gravity was just the friends we met along the way.

[@FirestormX9]

It'd be disappointing af then 😂

[@positionthepositron]

Now I have to try to understand this

[@positionthepositron]

Is this simply a metaphor for finding meaning? Or do you mean to say, gravity operates outside of time, and all matter is the under tension, to tend to the past, where matter was all coinciding at one point simultaneously? I feel this is possibly an aspect of quantum entanglement?

[@FirestormX9]

@@positionthepositron quantum entanglement is your state when your friends leave before paying the restaurant bill

[@lunchbokth4895]

I love you

[@picksalot1]

It might be better to think of Entropy in terms of "stability" instead of order and disorder. This could proved more insight in understanding "energy states" in the observable Universe. There are many "Islands of Stability" at every size and location, and we see that everywhere in our lives and surroundings.

[@MichelleHell]

It's best to think of entropy in terms of the energy available to do work. As the entropy of the universe increases, the energy available to do work decreases.

[@kxjx]

Right yeah entropy drives change. Interesting processes like stars or life take ordered energy and disorder it. Eventually all is disorderd and the same and nothing is interesting.

[@MyNameIsSalo]

I see entropy as a measure of usable energy, like an efficiency score on a washing machine or something. The lower the entropy of the energy you receive, the higher its efficiency score. Low entropy means energy is packaged tightly together in a form that is usable. Increasing entropy means you've used up useful energy and turned it into useless energy. High entropy is useless. Or you can look at it as the passing of time. Entropy increasing means something worthy of time has occurred. If entropy never increases somewhere somehow, then time does not pass. As we know time can move only in one way, then entropy increasing pushes time along its one dimensional axis. Entropy is what prevents travelling back in time. Entropy literality means everything

[@khatharrmalkavian3306]

This is excellent work. The difficulty at this level of physics, as you suggested, is that even if Verlinde's model makes all the same predictions as other models, until it can make predictions that the other models can't, there's no real way to test it. Otherwise we run the risk that it's just a complex way of expressing the same math without noticing that this is what we're doing.

[@Kyzyl_Tuva]

This is your best episode yet. I’ve been following this channel for many years. Look forward to more on this topic

[@xchazz86]

Gravity is probably just a property of time, we are looking at a 3 dimensional outcome of a 4th dimensional feature. If you were able to flow time backwards, then in theory gravity would be negative as a push force. Therefore gravity isn’t a force, just a marker of the property of time.

[@TheSCPStudio]

You’re just saying things without explaining the mechanics behind it.

[@requiemphoenix2891]

And what if Time is just an illusion caused by entropy? Or in other words, what if the flow of entropy is the so-called flow of time? With flow I mean the fact that entropy in a closed system can only be the same or increase. Now consider that gravity arrives from thermodynamics. The Higher the entropy the slower the change in increasing the entropy. Cool, higher gravity results naturally in slower time flow. I love this idea that gravity is an emergent property of the universe.

[@orbismworldbuilding8428]

I might be missing the point but if you reverse a video of someone jumping you still get footage of a pull force because them being pulled toward the ground happens on the beginning and end of a sequence, its closed

[@thenullvoidabyss]

⁠@@orbismworldbuilding8428no, u delved into something deeper about Causality and nature of close loops system. It might be very possible the very end of universe/multiverse is the exact cause for the big bang or eternal inflation.

[@blodbotina]

Such a beautiful journey into abstract thought

[@xavierzabie8184]

I mean if I'm understanding right this also works for the big bang. If the boundaries of space are ever increasing there is a restrictive force, gravity, pulling back. This restrictive force can be and is related to entropy. And therefore gravity = entropy. Probably don't see it as entropy because it's working on a scale so much larger than we can even fathom. So we've been calling it gravity this whole time. I'm sure there's holes, but not a bad thought. I'll have to watch this again later to confirm some things.

[@juliavixen176]

Keep in mind that the universe has no center, and the big bang happened simultaneously at every location in space.

[@xavierzabie8184]

If there's no epicenter how do approximate using Hawkin radiation?

[@DirtyMardi]

Just what I needed when my brain is switching to its most entropic state, i.e. sleeping. Now it’s going to be fighting that entropy for at least 30 more minutes.

[@Michael18599]

My thoughts exactly. That's why I'm saving this one for tomorrow morning.

[@juliavixen176]

Brainwaves are more regular and orderly while asleep... Which actually means they have _less_ entropy than brainwaves in an awake brain.

[@otaku-chan4888]

@@juliavixen176 are you sure? To me, an awake brain requires a _very_ specific configuration. Our personality, our thoughts, and very ordered perceptions that look nothing like the crazed randomness of dreams take place when we're awake- so being asleep gives rise to _more_ entropy in the brain! the problem here is that neither of us are correct. We don't have the slightest clue what a 'less entropic brain' looks like, so it's your unscientific word against mine : )

[@RCaIabraro]

My soul feels right with this.

[@GodIsADelusion]

Look at you teasing us with merch we can never get again. I put my It's Never Aliens and The Devs Will Hear shirts in the drawer for posterity.

[@davidwhiteford4936]

Gravity as an entropic vacuum created by the inherent deficit of cumulative information. Attractive theory, but to me at first glance it feels more like a thought experiment than a functional state. I will ponder it further, thanks!

[@AndrewBlucher]

It means that the stupider I am the heavier I am.

[@davidwhiteford4936]

@@AndrewBlucher Good extrapolation. We can call it "Idiobesity", or "gravocaloric impairment".

[@tomszabo7350]

Some of this is on the right track but the theory is putting the cart before the horse. Gravity is not an entropic reaction via the holographic boundary, it is entropic because time itself is a spatial metric pursuant to which mass creates "defects" that form additional units of space that radiate outward. The radiation of space due to the presence of mass explains the expansion of the universe and dark energy. As the space radiates it creates inward pressure on mass that is perceived as a gravitational force in 3 dimensions and this radiative pressure on cosmic scales explains dark matter. And of course this inverse relation between mass attraction and spatial expansion is why gravity can also magically drop out of the thermodynamics as explained in this video. The very reason we have an observable universe is because the gravitational and cosmological constants are closely balanced and therefore it will take a very very long time for entropy to reach its maximum.

[@themeeseman6950]

This is somewhat similar to what I have been thinking as well. Did you get this information from somewhere or come up with it yourself, I’d like to read more!

[@sageinit]

@@themeeseman6950 +1 to that question

[@Syphirioth]

If there is entropy at all and it not just the motion that overshots and pulls it back like an elastic to overshoot again. The pendulum is interesting you know.

[@Syphirioth]

@@themeeseman6950 This is my idea to. I can visualize it all in my head. Just try understand and visualize the known theories. Apply them in thought experiments. Like what was first? The egg or the chicken? Well I know the answer to. It was the egg. Cause the non chicken laid the egg that had the mutation that made it chicken.

[@carloguerrero6583]

wouldn't that push things away instead of pulling them in? " form additional units of space that radiate outward"

[@NefariousKoel]

This seems to be another suggestion that our universe exists inside a huge black hole.

[@juliavixen176]

The universe has no center location in space, and _might_ possibly (maybe) not have a boundary in space. (The only boundary is in time... in the past... at the big bang itself... which happened everywhere in space.)

[@selfsaboteursounds5273]

@@juliavixen176 Sure, but horizons are also time boundaries because they define how much information we know about something now as opposed to in the past. No reason an information horizon like a rindler horizon needs to be defined as a space boundary

[@VolodymyrLisivka]

We are inside infinite number of black holes.

[@drewg2403]

Unlikely depending on how you interpret whats happening inside black holes (which we ultimately do not know) but based on prevailing theory, there is a reason it is called an "event horizon." Beyond that boundary events in spacetime as we know them cease to exist. Spacetime is warped to the point where time no longer occurs.

[@VolodymyrLisivka]

@@drewg2403 "spacetime" is just a 4d array: [x,y,z;t]. It's model. You are basically saying that our mathematical model doesn't work in black hole.

[@Stinger-rq4gy]

Thank you for teaching me.

[@rossrhodes1963]

Now this needs multiple repeats. My head is spinning.

[@byronryan4216]

🫨

[@johnmckown1267]

The force keeping me in my seat is generally called laziness. 😊

[@davidwuhrer6704]

I call it inertia, but that's because I like to sound smart.

[@docpayce1]

Very honestly: WTF did you just tell me? Holy moley. What a ride... I will have to have a deeper think about that. Implications are crazy...

[@docpayce1]

After a few minutes: Wouldn't that link the 2-dimensional surface of the holographic principle to the 3-dimensional bulk in terms of gravitation being the limiting (i.e. linking) factor from 3D and 2D?

[@ganonfan98]

​@@docpayce1It's the other way around -- we arrive at Newtonian gravity if we assume the 2d boundary and 3d bulk are linked in the way discussed in the prior video, and driven by entropy. In other words, if we apply what we know about statistical mechanics -- which has only a few basic assumptions, the key one being equipartition -- to this model of a holographic universe, Newtonian gravity is "free". IF the holographic universe is true and IF thermodynamics is correct, Newtonian gravity MUST follow the law we know from classical physics!!

[@CATinBOOTS81]

@@ganonfan98don't forget also General Relativity, there's also a paper about that.

[@axle.student]

@@docpayce1 It's 4D. That's what makes it such a difficult realm to conceptualize. You can break it down into 3D and 2D to illustrate it, but ultimately in the end you have to treat it as 4D to make sense, which "Make sense" is an oxymoron for us humans when talking about 4D lol

[@captainpuffinpuffinson4769]

My problem with the whole derivation is that it uses the results from BH thermodynamics as a basis of its calculations It feels a bit like circular logic

[@BharathKumarIyer]

Thanks for covering this! I've been following this idea for the past decade and happy to see a video on it. Cheers!

[@mikebermea9366]

I have been working on a novel hypothesis for the last 2 years. I call it the time force hypothesis. It started out as a quest to understand gravity but ended up being much more. Not only is the idea a solid and plausible explanation of gravity, but it also explains the enigmatic phenomena of time as a mechanical action caused by the expansion of our universe. The basic premise of the idea is speculative at this point but is absolutely intuitive from a logical perspective. Essentially, it assumes that time is the 4th spatial dimension, and we, as threedimensional entities, reside on a membrane well-described by quantum field theory. This membrane is the fabric of our observable universe and is suspended in 4-dimensional space. A major event occurred in the 4th dimension, causing the energetic pressure on one side of the membrane to be higher than the surrounding 4D space. We know this event as the Big Bang. Since that event, our lower-dimensional 3D fabric has been thrust through the 4th "time" dimension. Our experience of this acceleration is both what we call time and gravity. In other words, we experience irreversible time because our 3D fabric is moving at an incredible velocity through 4D space. This is why matter has such incredible amounts of energy associated with it (E=mcA2), making the famous equation a calculation of momentum held within matter as we hurl through a higher dimension. The above description of time was derived from my attempt to define what gravity actually "is." Most people don't realize that the greatest minds in modern physics have no idea what gravity "is." So, I began researching the issue as a full-time job about 2 years ago. After thousands of hours and nearly 1 00 physics books, this is my idea. The Big Bang event was not the beginning of everything in 4-dimensional space but rather an energetic disturbance. It was the beginning of our 3D universe. The hot, dense moment created an energy gradient in 4D space, and this energetic pressure wave is the driving force of our 3dimensional fabric. Through Einstein's equivalence principle, we understand that this acceleration would affect our universal reference frame with the "equivalence" of gravity, hence the name "equivalence principle." I postulate that the perfect amount of acceleration since the Big Bang is what causes/produces Newton's Big G. Since this acceleration has been applied to our fabric, we have traveled an incredible distance. Variations in density in the early universe caused the fabric to deform due to varying inertial values, creating a surface topography described by Einstein's theory of General Relativity. If we adopt this perspective, unifying quantum mechanics and gravity becomes easy by removing it from the picture altogether. Quantum phenomena like waveparticle duality and superposition can be explained by the interaction of quantum particles in a stable 4D loop. Quantum entanglement and the measurement problem can be explained as intersections between particles along their paths in 4D space. Matter's natural frequency/vibration could be linked to stable 4D loops as energy packets race around their track through our 3D fabric's quantum field stack. On the other side of the size scale, we might speculate on what Dark Matter is. It could be nothing more than the residual warping of our 3D fabric caused by mass that progressed through the region at some point. This might be why dark matter exists in large amounts around galaxies and other large-scale objects. This hypothesis also explains Dark Energy, the 4th-dimensionaI energetic pressure that makes up 69% of the universe, creating a giant growing hypersphere that we reside on the surface of. The Time force is the remnants from the first cause that send us on this journey through time. In short, I propose a speculative but intriguing explanation for time, gravity, dark energy, dark matter, quantum entanglement, superposition, and waveparticle duality with one postulate (the 4th "time dimension is spatial) and one action based on the second law of thermal dynamics, all in the length of a KZbin comment. If you actually read this far and would like to read drafts of my actual scientific paper I have been working on for the last 2 years, email me at [e-mail]. It's a far more formal read, and I get into a bit of math, but I'm always looking for feedback.

[@loganfisher3138]

I hope that the followup episode that "picks this apart" will mention the work of Zhi-Wei Wang and Samuel Braunstein, which established that general spacetime surfaces that are not spherically symmetric and do not exhibit horizon-like behavior fail to obey an analog to the first law of thermodynamics. That undermines a major assumption of entropic gravity.

[@sageinit]

Got a title?

[@loganfisher3138]

@@sageinit "Surfaces away from horizons are not thermodynamics" arXiv: 2207.04390

[@sageinit]

@@loganfisher3138 thanks!!

[@drdca8263]

10:43 : wait, if N is the number of possible microstates, then the entropy should be log(N), not N. Surely the number of possible *configurations* is not proportional to the surface area, but rather the surface area is proportional to the *log of the number of possible configurations*, right? Like, as if each Plank length area portion of the surface had an independent (qu)bit? So, at 10:52 , should this N be “number of microstates”, or “log of number of microstates”? 10:58 : uh, ok.. (I guess this gives us a way to assign a K < (1/4) to any sphere surface in the bulk? 11:26 : why does it gain the same amount of entropy? I guess because the additional information it needs to describe is the same? Hm. Also, I’m not getting where this formula is coming from. If a black hole has entropy proportional to surface area, and the surface area is proportional to square of Schwartzchild radius, and the Schwartchild radius is proportional to the mass, then increasing the mass from M to M+m should increase the entropy from a M^2 to a (M + m)^2, an increase of a*(2 M m + m^2) (for some constant a) Oh, is this something about the de Broglie wavelength of the particle crossing the boundary? uhh, what’s the formula for that again..? For photons, E = h f , and lambda = c/f , So lambda = c/(E/h) = h c/E , ok that doesn’t appear to be what’s going on.. Edit: ah, I suppose the *Compton wavelength* (not de Broglie wavelength) is the one to use, with lambda = h/(mc) So, the 2pi(m c/hbar) depicted is, well, hbar=h/(2pi), so (mc/hbar) = (mc/(h/(2pi))=(mc/h) * (2pi) , hm, ok, so what they have written there is (2pi)^2 k_B ((delta x)/lambda) for lambda the Compton wavelength. Ok. Hm. So, if a particle with wavelength lambda travels a distance delta x, into a black hole? Why does the entropy increase by that amount?? 11:45 : oh, if I had kept watching he was just about to say it was the Compton wavelength. I’m unclear on why (2pi)^2 k_B would be “the minimum entropy” to add. It seems to make some sense that ((delta x)/lambda) could be like, “what fraction of the way through the one wavelength distance, had it traveled” I think, maybe. 12:50 : wait, but for the black hole entropy, K was (1/4), and in general it should be less, so, it can’t be 1! What?

[@sageinit]

First critical comment I could find after a while of scrolling

[@kindlin]

The fun thing about Black Holes is that their entropy is proportional to their surface area, not a log of microstates or anything else. I think that's why you just get a free N hanging around. Also, no need to try and pick this episode apart, I'm sure there are a MILLION things he could have asterisked and done entire other episodes on, but he's already lost 90% of his audience on the last episodes and 90% of the rest of his audience on this episode. Me and you may be in that rare 1% that actually thinks they understood most of this (thinks, mind you, because I'm sure neither of us has really dug into any of this on a formal level), but if he made this much more accurate or complex, we'd be totally gone, too. It's a fine line.

[@drdca8263]

@@kindlin well, he is talking about microstates a number of times throughout this. And, I think picking apart the parts one isn’t clear on, is a prime way to understand something better. Forces one to actually engage with the material, rather than forgetting the parts that didn’t seem to quite make sense as soon as it is over

[@binbots]

General relativity and quantum mechanics will never be combined until we realize that we are observing them at different moments in time. Because causality has a speed limit (c) every point in space where you observe it from will be the closest to the present moment. When we look out into the universe, we see the past which is made of particles (GR). When we try to look at smaller and smaller sizes and distances, we are actually looking closer and closer to the present moment (QM). 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 is what we perceive as the present moment and is what divides the past from the future. GR is making measurements in the observed past and therefore, predictable. QM is attempting to make measurements of the unobserved future and therefore, unpredictable.

[@drdca8263]

Are you aware that QFT uses special relativity, and therefore is using spacetime stuff? I think they probably have a decent grasp on “how does what we’re talking about relate to past/future”.

[@IronFairy]

12:07 - This sequence is SO satisfying

[@ektordarzentas]

Since it made sense to me that gravity is sort of the "opposite" of entropy this video makes so much sense!

[@susmitislam1910]

Is this not circular reasoning? Given that the Bekenstein-Hawking limit was calculated with a theory of gravity already. Although we could really change the perspective a bit, and assume that the Bekenstein bound is the more fundamental law, if we are to assume that spacetime is "informational" in nature.

[@livinlicious]

Gravity is by all likelihood not fundamental but an emerging property like temperature. Everyone will agree that temperature exists, but there is not such THING as temperature. On big scales we see it emerging the same as gravity. When you zoom down the concept of gravity goes away. The same happens with temperature. I don't really understand why we treat gravity as fundamental. There is no effect that is gravitational on the subatomic level. Before you complain, no orbitals aren't deformed because of relativistic effects they are because of quantum effects. Gravity on smallest scales simply is not existant. There is no gravity thing there. As an emerging property it's very real though when you combine all the mass of all the matter it creates this "force".

[@MyNameIsSalo]

We can say that about temperature because we have a way to measure it precisely, making formulas from very different fields of physics and all giving the same equations for temperature. We cannot do that with gravity due to the existence of dark matter and our inability to calculate it. If you make a measurement of gravity and find you are wrong by 70% because of some invisible stuff, then something has gone wrong. If you do the same with temperature, you can be accurate to 0.0000001%. Big difference

[@denissavgir2881]

Before I watch, I'd like to say this: I have been giving this thought and I have 3 ideas regarding quantization of gravity: equivalence principle (seeing how acceleration of motion behaves at the quantum level and extrapolating from that), time (looking from the perspective of time dilation gradients causing what's perceived as gravity and extrapolating from there), and tying it all in with the higgs field (looking at how interaction with the higgs field affects motion at the quantum level and tying it with the previous two), and then statistically modeling it all to see how gravitation emerges at the macro level. Perhaps gravity is just a statistical phenomenon of quantum events, similar to how the probablistic nature of quantum physics becomes deterministic once the particle count becomes huge enough to where it becomes a matter of statistics. Many people don't understand that quantum mechanics doesn't "break down" at the macro level, but rather that at the macro scale, we can only see the statistical behavior that emerges when huge amounts of particles are at play. A ball can quantum tunnel through a wall, but only if almost all of its constituents happen to quantum tunnel simultaneously and end up in positions that would perfectly replicate the original ball, which is so unlikely that you'd need an eternity for that to start happening. This example is meant to be analogue to my idea of gravity behaving differently at the quantum level. So perhaps just like there are no quantum basketballs, there is also no quantum gravity, but rather an emergent phenomenon that only behaves like general relativity's gravity at the macro scale, all caused by the statistical outcome of quantum particles' motion being affected by the higgs field, time dilation, and the physics of acceleration. If you look at gravity from this perspective, it ends up being more of an imaginary or pseudoforce, manifesting due to the behavior of interacting quantum fields (including the higgs field) at different velocities and rates of time. I have seen an example that shows that the time dilation gradient caused by a warped spacetime field causes an object's particles' motion to be affected along the gradient, which ultimately causes the object to change direction and fall (Science Asylum channel), and this led me to forming the aforementioned idea. Being that I am not a physicist but rather a slightly autistic fan of physics, I lack the skillset to express these ideas mathematically. But what I described is what I saw in my mental physics simulator, and hopefully, this provides enough insight for you to understand what I'm trying to express.

[@SynthwaveDuck]

This is actually quite intuitive

[@chriswhite599]

I freaking love this channel

[@osmosisjones4912]

Maybe gravity isn't a force but accumulation of all tractive forces

[@transfered]

I moaned when I saw new spacetime video notification

[@TheSCPStudio]

What an intellectually challenging comment appropriate for this channel/topic.

[@peter5.056]

I've been thinking this was the case since my high school physics class. I even wrote a paper on it, and I got a C- on it, for it being "science fiction."

[@GehadIbrahim-f3p]

Thank you God for your putting your brilliant mind in this platform Fantastic I can't help to findy any other professional physics than this

[@myBestWishes677]

Thank you so much for this explanation of Verlinde's theory!!! One of the best videos of PBS Spacetime!!!

[@tuqann]

For the historical record, both fire and water were considered 'elementary', we now know the former is a form of plasma and the latter to be a molecule. Some day in the future I am sure people will say "remember when we used to think gravity was a fundamental force?"

[@Saintjackoftrades]

The actual fire part of fire is actually just gas.

[@abhir7823]

In that sense nothing is fundamental As we keep discovering more we find deeper layers ... like an Infinite onion

[@symmetricat188]

@@Saintjackoftrades The actual "fire" part of fire is actually just electrons having an existential crisis.

[@uzanym6919]

@@symmetricat188 I love your definition of fire/plasma.

[@tsm688]

fire is not plasma, the same way vacuum is not gas Plasma has specific, testable properties. It's extremely conductive -- not "a few less megaohms than empty air" like fire, more like "we need special measures to stop it from forming dead shorts across our circuit breakers" conductive. And it bends dramatically around magnetic fields. And it is fundamentally corrosive, eroding every known form of matter with its raw charged nuclei. Fire is none of this, unless you "help" it by pumping so much extra energy into it that it really does become plasma.

[@ravenlord4]

Graviton researchers have left the chat . . .

[@CATinBOOTS81]

My favorite kind of spacetime episode, the one which I can barely follow. Ah, I missed those, they were once more common! It wouldn't be interesting otherwise! Gotta use those neurons! 😂 Had a great laugh at 13:37, the derivation of General Relativity from the Enthropic Force at the Boundary of an Holographic Universe could be probably be the more mind melting episode of Space Time ever! 🤯🤯🤯

[@mogilews]

Really looking forward to the next video in this sequence, which I believe will be orbiting around the idea of "Induced Gravity", aka "Emergent Spacetime" (per Van Raamsdonk, ChunJun, and others), where the spatial dimensions are themselves emergent. I'm not a megamind physics guy, but honestly, I feel that emergent spacetime should *precede* entropic gravity. It ties it together.

[@willd4686]

Well boys looks like we're going to be rewatching this one a gazillion times

[@joz6683]

I have always thought this. Gravity is an emergent effect. Looking for a force carry is akin to looking for a sound particle. Sound is a compression wave, and gravity is the same, a compression wave in spacetime.

[@asdfasdf-dd9lk]

i mean phonons are a thing, and crazy important in multiple field of physics. That said, they are an emergent property too; that doesn't make them anything close to useless though.

[@JasonEdelman66]

​@asdfasdf-dd9lk so a physical photon travels from the sun (or a light bulb) thru glass and warms your face? see previous comment for source..

[@vaelophisnyx9873]

@@JasonEdelman66photons are a wave and a particle

[@juliavixen176]

Yeah, "photons" are really more of a mathematical tool than anything actually physical. The electromagnetic field is continuous, but sometimes you want to be able to talk about the smallest meaningful part of the field involved in some interaction with something else, and _that_ part is called a "photon".

[@asdfasdf-dd9lk]

@@juliavixen176 huh? the only way you could say photons aren't physical is if you dived too deep into epistemology or something. Photons are very real.

[@johncowart9536]

Finally we're doing ERIC! WOOT!! Love his lectures

[@jamesm1494]

Released 59 seconds ago and NOT the first!

[@mikapeltokorpi7671]

It happens. Apparently YT videos are downloaded in different regions at different times. And thus you may never be the first for certain popular channels.

[@gravitationalvelocity1905]

Great Episode. So, here is my question: How does this explain time slowing down in a gravitational field? How would tendency to move towards the high entropy configuration cause time to slow down in that region?

[@LiftandCoa]

This is by far the best channel on youtube. Lovely, lovely stuff.