The Black Hole Entropy Enigma

[@wabznasm9660]

"Let's figure this out" nah mate you go on ahead, I'll wait here and nod if I hear a word I know.

[@suri_youtu2463]

😂😂

[@ruatsangawhite7261]

🤣🤣

[@douglaswinters9695]

I recognize a lot of words by themselves. It’s when he puts them together into sentences I get confused. Am I not supposed to nod through the whole video?

[@BurningRoman]

LOL

[@MoshkitaTheCat]

That’s hilarious!

[@michaelriley8879]

Anytime I'm feeling too smart, I come here to be humbled.

[@Dutchman536]

When come back here , do you understand it , if one is smart, can he be too smart , or can we find these answers on the surface of my thinking , is arrogance lost in a blackhole

[@ducky36F]

The more you learn the more you realise you know nothing

[@mrcesarnieto]

the only show I rewind several times, get that I'm just not there yet, and love it still

[@secretagent0280]

LMAO.

[@mangalvnam2010]

Me three and a half!

[@Mritunes89]

I know this proably won't be read, but I want to thank you guys for putting these videos out. Physics is one of my favorite subjects and has inspired me to study physics in college. So thank you guys for the great videos, and keep them coming . :)

[@glendrake9268]

I read it!

[@asshatteryengaged813]

Aye 👍

[@tnetroP]

Read it!

[@frankschneider6156]

Can't read but looked at your photo and the letters that don't make sense to me. Does that count ?

[@jackmuller5478]

it was read

[@exoplanets]

Each of your videos is a joy !

[@alexandermartin1837]

The Exoplanets Channel indeed !

[@rubenmartinez2994]

Videos for the ignorant and the indoctrinated.

[@PabloMartinez-kx9yq]

The Exoplanets Channel i totally agree

[@dna7767]

@@rubenmartinez2994 maultaschen

[@rubenmartinez2994]

Do you mean A Schwäbisch Maultaschen (Big, Fat German "Ravioli"), this is more believable than a black hole.

[@michaelblacktree]

So that's where the holographic universe theory came from. Thanks for explaining. So many other KZbin channels feel like they're sucking IQ points out of my brain. I come to PBS Space Time to get them back. 👍

[@secretagent0280]

Same. As far as feeling stupider after observing certain content.

[@PhoenixT70]

Max0r in a nutshell.

[@robertcaracuda2363]

Great video, as always. You made this channel something amazing and unique. Lots of love, keep the great work up.

[@StarCoreSE]

I could umderstand old episodes. Now each new episode is overly complex for a non-astrophysist person. I keep watching them without understanding anything. This channel has really lost quality over time. Knowing physics is a skill, but teaching them understamdably to someone who doesn't have 4 phd is another skill...

[@WarrenK2]

Star Core watch them again, they have a very intuitive rhythm to the videos. Top notch I say. Way more in depth than NDT does on Star Talk, love it.

[@coolkatmehrfth]

Star Core if you have watched all the videos, you should have built a good enough base of understanding of the core concepts of physics to understand these videos

[@frankschneider6156]

Star Core This stuff is neither complicated, nor badly explained (actually is the pedagogic approach nearly perfectly executed). If you don't understand a word, the problem is clearly you, because you are very likely missing some essential basics. Some things require a certain level of knowledge and can't be explained without it (if you don't think that's true, try teaching a 3 year old, what mutation via photo-dimerisation of DNA nucleotides means and how it works in details). You'll also have a hard time learning assembly, if you don't know what a CPU is. Similar with some newer aspects of physics.

[@guanche011]

Holy shit.. I had a "Holy Shit" moment seeing how the holographic principle could make sense.. Thanks for going in (casual-conceptual) depth!

[@tesseract3966]

I had the exact same thing. Mindblown!

[@anubisvex3309]

Pretty much describing how an eyeball works

[@Hecatonicosachoron]

The holographic principle makes sense, you just need to hear several detailed explanations a few times. Reading a few important papers also helps, but they are not written in an accessible style. You just have to keep in mind that the "hologram" is not necessarily a physical object, but a *theoretical* correspondence of quantum gravity in N dimensions with a lower-dimensional quantum field theory (in N-1 dimensions).

[@GenevaRob72]

Renzo I thought the holographic principle was disproven?

[@alexandruianu8432]

GenevaRob72 Uhm, no it wasn't.

[@ASLUHLUHC3]

Yesterday I watched your video on entropy with no intention of learning about black holes and the holographic principle. I love this channel!

[@painzockt]

Quantum information is stored in the balls.

[@yanisgarcia7602]

Pain Hyena Just like pee, coïncidence ??

[@kapsi]

Yes papa

[@asvpab]

Fax

[@BaldingClamydia]

@@yanisgarcia7602 pee isn't in the balls lol

[@Krokoklemmee]

I mean... you're not wrong

[@llcn829]

I love the new aesthetic of your graphics! Keep up the good work. This is one of my favourite channels on KZbin.

[@0dWHOHWb0]

Oh, was just about to go to sleep It can wait

[@Premed1981]

same :) GMT+3 here

[@DodoRecordings]

Woke me up, while falling asleep listening to another episode :-)

[@hillarycorona8249]

Where are you? It’s 5:30 pm here

[@justin.187]

Hillary Corona it's 436pm here in LA

[@DodoRecordings]

@@hillarycorona8249 Netherlands, 11:30 pm

[@energymaster7]

Coming back in 2020, this one is one of your best scripts. One of the best videos of yours.

[@AlexDesise]

I consider myself to be a somewhat intelligent person. I'm not a genius nor am I dull but every time I try to attempt to follow these videos I get lost after about 20 seconds. I feel like a total moron but would still like to thank the PBS team for these videos. They are highly informational and what pieces I can comprehend are very well explained and produced.

[@shanebailey9128]

Ever heard of the “Dunning-Kruger effect”?

[@SolaceEasy]

Enjoy your break, and thanks for leaving us such a well planned out series of vids.

[@1cyanideghost]

I really love your videos, always look forward to watching them, thank you and everyone involved in making it happen.

[@TheMildConfusion]

I'm amused that your shirt near the end says, "The heatdeath is coming" considering how closely you resemble Tyrion Lannister. Also a shoutout to serialized content. Great video, by the way.

[@JoshuaHillerup]

Wait, can you go back and explain how you can reduce the mass and radius of a black hole without reducing the surface area?

[@NavarroRefugee]

That does reduce the surface area. It only happens via hawking radiation, which he explicitly lists as the exception to that rule.

[@VuvuzelaTM]

You can't. Any interaction with the black hole will increase it's mass. BUT... You interactions with it's gravitational field can decrease its momentum and consequently decrease it's energy. Right?

[@JoshuaHillerup]

@@NavarroRefugee he said that merging or extraction rotational energy would reduce the (combined) volume, but not the surface area.

[@asshatteryengaged813]

I can wrap my head around mass decreasing (less stuff in the same space). But I thought surface area of a sphere is a function of radius. My mind is blown. 😨

[@burtosis]

@Thiago Reis. Not really. You just need to dump negative energy into the black hole (Hawking radiation). Vacuum fluctuations cause a particle-antiparticle pair to appear close to the event horizon of a black hole. One of the pair falls into the black hole while the other escapes. In order to preserve total energy, the particle that fell into the black hole must have had a negative energy (with respect to an observer far away from the black hole). This causes the black hole to lose mass, and, to an outside observer, it would appear that the black hole has just emitted a particle. In another model, the process is a quantum tunnelling effect, whereby particle-antiparticle pairs will form from the vacuum, and one will tunnel outside the event horizon.[

[@epocfeal]

The definitions of entropy had been hammered into my brain for the last 2 episodes and then a lot of things were just casually thrown out at the end leaving me with one big "wait... What?"

[@noxabellus]

Man, PBS Space Time has some of the best infographics on KZbin. Aesthetic!

[@jamesaltonfilms]

Who is the designer of all the typesetting, animations and colour sequences? They're absolutely stunning!

[@XrollhaX]

A black hole video! I've been waiting for this moment. Got trapped inside of one and I'm waiting for you guys to find a way out.

[@VA-ph2ml]

2nd law of thermodynamics, do not talk about thermodynamics.

[@nosuchthing8]

Words worth fighting for

[@benoregan4623]

That's also the first law of thermodynamics.

[@redshiftedlight205]

Yes it does

[@medexamtoolscom]

Coincidentally, that's also the 1st and 3rd laws.

[@addyyyyg]

*First law of thermodynamics-can’t break the “Fight Club” theory

[@ChrisNihilus]

String Theory! Finally. I was expecting this moment for so long.

[@techman2553]

Some random blackhole questions from a curious layman that felt like asking the expert commenters... 1) Is there a maximum size to a black hole ? What if you feed a blackhole everything in the universe ? 2) If 2 blackholes are close to each other, are their event horizons still spherical, or do they warp ? 3) Can 2 blackholes orbit eachother close enough that their event horizons overlap ? If so, what happens to particles that cross the overlapping horizons ? 4) Can a smaller black hole be torn apart by the extreme gravity of a nearby giant blackhole ? 5) Does a blackhole have a temperature ? 6) Does a blackhole have regrets ?

[@robinsuj]

I can honestly answer 5: Yes, and it's indirectly proportional to its mass (yes, the larger the blackhole, the lower its temperature).

[@TurkeyMeat]

I would like to see that citation lmao they are literally the densest thing in the universe. Here's a stackexchange calculating some densities physics.stackexchange.com/questions/26515/what-is-exactly-the-density-of-a-black-hole-and-how-can-it-be-calculated. Even a galaxy-sized black hole is 200kg/cubic meter.

[@ballom29]

200kg/cubic meter is nothing. Neutron stars are around thousands of ton per centimeter cube But the singularity of a black hole got the cake, it has an INFINITE density...because it have a volume of 0

[@robinsuj]

Yes and no. The thing is, all of a black hole mass is in the singularity at its center. Not evenly distributed along its volume.

[@TurkeyMeat]

To an onlooker it would be equivalent but yes. And that is galaxy-sized schwarzschild radius which is insanely large.

[@mantisproductions31]

Fucking love this channel. Thank you for existing, everyone who is a part of making this channel

[@josephelston4101]

Lovin these vids, please never stop doing this

[@CCCW]

Man, this is just one of the best channels on KZbin

[@necrosodomblasphemia]

how come gravitational waves and the penrose effect can decrease the radius of a black hole but not the surface of the event horizon?

[@robinsuj]

They can, just as applying work to a system can decrease its entropy.

[@ramyhhh]

necrosodomblasphemia the surface of BH is not perfectly smooth, it has wiggles which allows for more surface area than a perfect sphere

[@leobidussi5039]

The Penrose effect is a process whereby you can subtract energy from a rotating BH. This kind of BH doesn't have a spherical event horizon, but it is rather an elipsoide, so it doesn't have just a radius. Once you have extracted all the rotational energy from the BH, you are left with a Schwartzshield BH, and when you compare the surface area of the elipsoidal BH with that of the spherical one, you find out that the latter is bigger. So during the entire process you are subtracting energy while increasing the surface area of the event horizon

[@frankschneider6156]

necrosodomblasphemia 2 merging black holes loose mass / energy in form of gravitational waves. If the masses are M1 and M2, the resulting mass Mres will be Mres < M1 + M2, because deltaM = M1 + M2 - Mres is emitted in form of gravitational waves. for the surfaces this means: be the surfaces of the merging black holes A1 and A2, the resulting surface Ares will still be Ares > A1 and Ares > A2 this means the surface only increases. Thus you can reduce the resulting mass Mres, while there is never a decrease of a single black hole surface (although of course Ares < A1 + A2).

[@leobidussi5039]

@@Binyamin.Tsadik actually the area that we are talking about is precisely the area of the event horizon. Below the event horizon there is by definition the black hole.

[@Zdman2001]

Dang, this one just blew my mind. First new major concept I've hit in quite a while. So, awesome!

[@alessandrocapurso2977]

if we see spacetime not in 3D space + 1D time, but as a 4D Hypersphere quantised on Plank Units, with 2D "Real plane" Space (kind of holographic hypersphere surface expanding that bends according to mass) and 2D Imaginary plane of time, it all seems to make sense, from quantum to relativity... We can consider, as "axes" of time, an Absolute Time of "evolution of the universe" (iT, a kind of tick as the Plank Time perpendicular to the Real plane) and a local time of "quantum blurriness" as e^(it), that we perceive as third spacial dimension developing linearly e^(it)... then a universe of possibilities could start evolving... considering elementary forces particles as vibration "shifted in time" relatively to the surface (maybe the famous string theory extra dimensions :) even the "un-existence" of magnet mono-poles or quark mass could be explained and black holes and dark matter figured out... The local time maybe could also be called free will ;-)

[@tlreclipse1126]

Brilliant video, really like where this series heading keep up the good work Matt!

[@piotrgpt-4178]

I love how this channel stimulates my intelect tho some subjects are just too much for me :(

[@rszabla]

Wow what a series! All the episodes are coming together... Super excited to see where this is going

[@Binyamin.Tsadik]

Holographic principle just makes sense mathematically. A higher dimension can always be projected onto the surface of a lower dimension. Basic engineering blueprints contain all the volume information about any component simply by projecting the volume onto 3 planes. A 2d drawing can be projected onto the perimeter and recreated The only exception is that a 1d line cannot be projected onto a 0d point. But a set of 0d points can't exactly surround a 1d line.

[@garethdean6382]

Yes, but if I want to draw all the details of an object twice as long on a side, containing 8 times as many equally intricate parts can I do so on a blueprint 4x the size but no more informationally dense?

[@Binyamin.Tsadik]

Blueprints only capture 3 sides and sometimes an isometric picture. The other 3 sides are usually redundant. It doesn't really matter how complex the volume is, a blueprint can always capture it. You could ideally capture an entire car's engine in a blueprint, but it's simpler for us to understand it when we separate out each component into its own blueprint. Effectively, a 3d printer large enough could print out anything as long as it has 3 perspectives of that image.

[@garethdean6382]

I'm still not convinced. Imagine taking a 3D object, an engine, and making a blueprint with a resolution of x. Now we make a 3x3x3 block of engines and try to draw a blueprint that contains 27x the information on 9x the area. You're going to need one of two things. Either you're going to need to increase the resolution of the blueprint, which we have a limit on (X can be our planck length.) or you're going to need some way to simplify or encode that information. Also I'd be interested in how a 3D printer could print a box with a ball in it only using different perspectives of the outside of that box. There'd need to be some way to get a complete internal shot, and if the box walls count as information then we can't simply render them see-through. Encoding seems like the path to follow, but that's easier said than done. How exactly do you losslessly encode ALL the information in a volume of any given size onto something proportional to its area? If you can crack that write a paper because nobody else has yet.

[@ezzie_baby]

I absolutely love this channel oh my god. thank you so much!!!!

[@redahessi4101]

Quality content, as usual!

[@elsenorcostaricence]

this is absolutely the best channel on the internet

[@garavonhoiwkenzoiber]

I UNDERSTAND quantum mechanics... but " 'T Hooft. " that's where I draw the line buddy!

[@GRasputin91]

Thats one of the mysteries of language

[@SharperthanA]

Finally a great video to explain to friends how these complex ideas came together to form the basis for the holographic principle!! Thank you

[@druid_zephyrus]

I love this fucking channel. It is understandable, digestable, and exciting. Yet every now and then it goes above and beyond and literally blows my godsdamned mind! Thank you. Just thank you. I feel so small and inept yet satisfied that there are those that not only stretch our understanding, but just want nothing more than for others to catch up. I work in a field where the individuals I support can be very selfish or self centered and my most fervent goal is to get my guys and gals to instead want to build others up to their level rather than brag that they are on another level. An episode like this, where all the lessons and conversations have started to come together in such a way that anyone could realistically follow just for the sake of building an increased collection of people at a higher level of learning...gods it gives me a mind boner so hot and dense it might be a blackhole. And this is not even enough to say alone. The support of the comments section and those that will have personal conversations when someone falters. The channel, the community, scratch that, the FAMILY propagated by spacetime is just ...is just...indescribable.

[@zetiks]

Those new layout for entropy and black hole graphics are beautiful.

[@joedoe3688]

What happen to Dark Matter when reaching the Schwartzschild radius of a Black Hole? Will it information also be imprinted on the surface and later with Hawking radiation emitted? So converted into usual matter? Can this be observed and so Dark Matter be proven?

[@TurkeyMeat]

Well we can't observe information from hawking radiation quite yet, but that is interesting.

[@Bradgilliswhammyman]

You make a great point and a intriguing prospect for a experiment. How would hawking radiation be detected?

[@TurkeyMeat]

It isn't the detection that's the issue it's confirming whether there is information encoded on it.

[@frankschneider6156]

Mohammed Lee Dark matter obviously has mass (that's how we call gravitational charge), so why should it behave differently from classical mass when falling into a black hole ?

[@frankschneider6156]

neil u For the same reason that neutrinos simply pass through you, because it doesn't interact via EM. This means DM interacts with itself gravitationally accelerates towards each other, then doesn't "collide" but due to lack of EM interaction simply passes through each other thereafter it is is gravitationally slowed down until it moves again towards each other, passes through and so on and forth endlessly. As DM is considered to be relatively hot (fast moving) the distances are larger and thus it doesn't aggregate into small amounts of space as ordinary matter does. It's more like hovering around (and through) a center of gravity.

[@revenantnox]

One of your best episodes yet. Thanks.

[@feynstein1004]

4:50 Hang on. If entropy is equivalent to information, then shouldn't a black hole be a higher entropy state than before because like he said, the more entropy a system has, the less certainty we have about its various properties and black holes are pretty much the pinnacle of that. We logically can't know anything about a black hole (save for the 3 properties), which means its other properties could be pretty much anything. Isn't that the definition of maximum entropy?

[@garethdean6382]

Black holes are very high entropy, but not the highest possible entropy since we know things like its volume and density. Any given 'bit' of energy in a black hole is limited to a certain volume, if it has a property such as charge then there must also exist something that 'balances' that to give the hole's total property. (So a neutral hole cannot contain an electron without also containing a proton, positron or other positively charged particle.) Holes can evaporate at which point the volume a 'bit' of energy can be in becomes unlimited. You get a specific set of particles (mainly photons) but this will always be so many of such low energy that they more than compensate and be higher entropy over all.

[@snowballeffect7812]

From 10:30 on, I am just going "holy crap! that's crazy! and somehow it still makes sense!" This channel is frickin' amazing.

[@ogdzqbjqbu]

Does the holographic principle imply that the universe either can't be infinite or can't be uniform? Let's say that the average entropy density of the universe is 1 unit per square meter. Then the entropy inside a region of space would be proportional to its volume while its maximum possible entropy would be proportional to the region's surface area. I could therefore designate a large region of space that contains more entropy than its maximum, which would imply that either the universe must be smaller than this region or that the universe's average entropy density per unit volume must tend towards zero.

[@burtosis]

One way to look at it is the maximum entropy of the *visible* universe is bounded by the same principle. However, every point in space has a different boundary, even your own two eyes are at two slightly different centers of the universe. We know from how flat space is that it must be at least 1000 times wider than we can see, it may in fact be infinite. Space is mostly empty which is something to consider. You also can't exceed the maximum entropy density as that just creates a (larger) black hole. Remember, a few million solar masses fits into a size smaller than our solar system.

[@loungelizard836]

I'm starting to get it now! Thank you for this excellent presentation!

[@gotbread2]

Lets assume i start to stack little boxes in a volume of space. Each volume contains one bit of information/entropy. The information content of that volume of space grows with R^3 but according to this idea the maximum amount is limited by its surface area. So at some point my volume would contain more information/entropy then allowed for a given surface area. Is this coincidentally the point where my boxes collapse into a black hole?

[@TurkeyMeat]

The whole point of the hologram theory is that the volume inside of your boxes does not affect how much entropy can be stored. The surface area of your chunk of space that holds the box is what determines that, since the 2d imprint is projected as the box, thus only the outside area affects information storage.

[@michaelbuckers]

Volume is immediately greater than surface, there is no threshold. The idea there is that the surface area is enough to encode entire internal volume, you don't need to actually fill the volume with data. If you take all oscillations on the surface and add them up, you get reconstructed internal volume of, any complexity. Speaking of coincidences, the observable universe weight has schwartzchild radius that coincides with observable universe radius. It doesn't says though that the universe is a black hole. But it explains that the universe is bound by an event horizon, the same way a black hole is bound by event horizon, except inside out.

[@shastro6939]

If its true that the observable universe has a schwartzchild radius that is the same as its radius, that would be amazing. I googled but found conflicting answers, by chance do you have a source for that? or any more information, id love to read up on it.

[@Julian-by7on]

yeah

[@drdca8263]

Well, why not try calculating it out? Take the formula for the Schwartzchild radius of a mass, and a given mass/volume density, and a given information/volume density, and look at what radius of your big ball of hard drives the schwarzchild radius of it becomes more than the radius of the ball. I've tried doing this though, and I might have made a calculation error, because I don't think the answer I got seemed to mesh with the most straightforward interpretation of that? I don't remember exactly what result I got. I think it seemed backwards in some way, like, something was in the denominator when it seemed like it should be in the numerator.

[@Danilego]

Wow, you guys made so many episodes that help explain this one, it’s almost like the MCU!

[@nigel0001]

PBS Space Time OR 'this is really interesting and confusing at the same time' .

[@AJarOfYams]

same

[@AlexanderGarcia-og9cr]

_

[@constpegasus]

Incredible. Keep these videos coming please.

[@MrExclaimed]

LOOP QUANTUM GRAVITY VIDEO PLS

[@LordAlacorn]

This. I like this man

[@moonshake1234]

flippin' yes

[@cezarcatalin1406]

That would break entropy so hard... I mean... the universe is supposed to have slightly negative curvature but LQG actually shows that it could change it's curvature at random... Imagine snapping between the inner and the outer side of a torus (and everywhere in between). What is scary about LQG is that it shows that our existence is truly a random event and that information leaves and goes whenever it pleases as long as it does not break time, spin, chirality and charge symmetries.

[@andrewbartram7688]

The holographic principle actually contains a solution for quantum gravity. In much the same way as it's encoded on the 2D space.

[@poll-lie-ticks1776]

The evidence doesn't look good for LQG, as unlike String Theory, LQG theory has undergone at least one experiment, which it appeared to have failed. What was the experiment? LQG states that over extremely long distances different colours will move through spacetime at very slightly different rates. Data from GRBs over 5BLY away showed that light, regardless of its colour arrived at the detectors at exactly the same time to an error ratio of something f*cking ridiculously small. This doesn't disprove LQG, but like for instance, like the LHC not finding any super symmetric particles so far, this experiment regarding light colour and LQG doesn't bode well for it.

[@MrSunny421]

I always want to understand these episodes and start off strong but usually end the video having gotten lost. Fascinating none the less 😁

[@ASLUHLUHC3]

Now that I think about it, the 'microstates and macrostates' definition of Boltzmann entropy is clearly *not* an objective measure, and thus probably shouldn't be used in physics. This is because it varies depending on the knowledge one has about the system and what one regards as distinguishable macrostates. For instance, consider an opaque box that contains feathers. According to Boltzmann entropy, one would say there is high entropy. This is because there are many possible feather positions (microstates) that would leave the box appearing the same (macrostate). However, it may actually be the case that the feathers inside the box are highly ordered, and thus there would objectively be low Shannon information/Kolmogorov complexity. Unlike Boltzmann entropy, this would be the case regardless of whether the box is opaque or whether you could somehow identity different feather configurations from outside. So are we thinking about black hole thermodynamics in the subjective Boltzmann entropy way? Surely it's wrong-headed to attribute high entropy/information to black holes just because we can't see inside it. For all we know, it's chock full of order, and thus has *low* Shannon information/Kolmogorov complexity.

[@somewherenorthofstarbase7056]

Good points

[@kylebell6239]

Atleast someone understood the video

[@prosimulate]

I completely agree, just because we cannot see inside we hit the high entropy conclusion. Strikes me that when matter falls into the BH the fact that space and time probably “divorce” each other at the EH what we end up with is a kind of ordering because space is being pulled in faster than light can escape it’s almost like a bubble per se a light bubble becuase light is trying to pull away but cannot. I cannot imagine any molecules, atoms or particles inside the blackhole. If time itself has divorced itself from space then particle decay might occur instantly since time is no longer a dimension inside the blackhole. Just thinking…

[@bruzote]

Regarding your comments about the claim black holes are high in entropy when we can't see inside them, I suspect black holes are claimed to be "high entropy" RELATIVE to their density. Right off, I would like to know if that is right or wrong. But that seems like a very reasonable assumption about the narration. After all, a black hole with a mass equivalent to one photon of 550nm light probably would not be considered to have much entropy, regardless of who is narrating and what ideas they subscribe to. As for most entropy of the universe being in black holes, I suspect that claim arises from the reality that galaxies can have superdupeultrauber-massive black holes at their center. I agree the state measures are subjective. I think the concept proves useful, and nobody has improved on the subjectivity so they just accept the microstate model as the best we can do. I believe for thermodynamic entropy, the microstates are infinite. How could you not have infinite locations? Even if Planck volumes exist, that doesn't mean some arbitrary grid exists with firm boundaries on each voxel. I suppose that is possible, but it seems highly speculative to make such a supposition.

[@canyadigit6274]

Wait...do you feel it? There is this happiness in the air...wait a minute... PBS SPACETIME UPLOADED!!!!

[@supreme84x]

Doesn't the Quantum Eraser experiment destroy information? When the information of which slit the particle goes through is destroyed, we get a wave pattern. If it isn't destroying information, what is it?

[@intialmayhem6973]

A wave function has less entropy than an a solid state when not being observed. So, infomation isnt being destroyed but being spread out to an equilibrium state.

[@frankschneider6156]

Lance Guimont Do you have ANY reliable source for that statement ? E.g. a university textbook or paper or something ? If at all a wave function should have a lot more entropy, as a localized particle as it is smeared across the whole universe. Therefore the uncertainty of is much higher should thus have a significantly higher entropy than any localized particle. If 3 degrees of freedom are completely unknown it's very hard for the 3 speed vectors with their upper boundary of c to overcompensate for that.

[@adamgalloy9371]

From my (admittedly limited) understanding of the PBS SpaceTime videos depending on your interpretation of QM information is destroyed or conserved during this experiment. If you take the "Copenhagen " interpretation then the wave function collapses into a single state and all other states are lost for good (and information is not conserved). If you use an interpretation such as "the many worlds" interpretation, then the information is not lost it's just in another parallel universe we cannot see. Can someone else confirm/deny this?

[@upgrade1583]

university textbook lol

[@RedRocket4000]

That is how I recall it. I just did not get why Black Holes eating information that would not get out had to be a problem when information sent to a parallel universe is lost to our universe so effectively destroyed. Also, do not know why quantum information being destroyed messes up the rest of the theory as there is no use for this information except for an​ all powerful all knowing god. And 2nd Law is being held up by the expansion of the Universe in theory by dark energy. Without out this expansion gravity would trump the second law and organize everything in a big crunch. A theory is supported by an event that seams outside of it make the theory seams ordered by a god. I like the concept of deism. But I question ideas that seem to be the actions of a god in nature to keep a theory valid.

[@8cordas381]

Is it the surface area of the black hole or the event horizon's area that is affected by the collapsing star's temperature(or entropy)?

[@MichaelLloyd]

If I ever die (debatable, I plan to live forever) I want to be buried wearing a t-shirt that says Maximum Entropy. That'll show "those bastards" (whoever they are...)

[@jezusbloodie]

We can tell those bastards directly. We'll have quite some time to figure out who they are and how to find them!

[@frankschneider6156]

Michael Lloyd Good plan, but I predict shitty execution (e.g. by dying)

[@LordMichaelRahl]

"Not a great plan".

[@buttsufancypantsu1644]

I mean whoever reads it will be in a higher entropy state than your corpse (assuming it's a human), so maybe rethink that plan sometime between now and when you maybe die.

[@MichaelLloyd]

The will have energy to offer, I will not. How does that make them have higher entropy?

[@jakegrist8487]

Matt, I'm really troubled by a seeming paradox with event horizons. Please help. Here are the premises of a seeming paradox: 1. As mass approaches the event horizon, time, as measured from a distant outside reference frame, approaches a total halt. 2. Hawking radiation is a continuous process, as observed from the outside, and does in fact move real mass from inside the event horizon to being back on the outside. If these statements are true, doesn't it follow that all mass has to evaporate as Hawking Radiation before it can cross the horizon, as observed from its own reference frame? That is, basically in the same moment it falls into the horizon, it explodes back outward? So, to a black hole, black holes never form. Please help. It's keeping me up at night.

[@danielmihalik2785]

Wait, how can a black hole's size decrease while the surface area remains the same? Does it morph into another shape? And if it completely disappears, wouldn't that decrease the surface area to 0 or something?

[@levinotjeans]

but the event horizon can change size

[@Tomatoffel]

wait so it loses gravitons and the rest still stays? or how can i interpret that answer darjan? I still dont get how a small black hole that just hawking radiates away keeps his surface.

[@Kalenz1234]

Considering the singularity itself has no width, length or height the surface area already should be 0 right? unless he talks about the surface area of the schwarzschieldradius. In either case I don't see how the surface area can only increase. He really should have specified and explained that better.

[@septitais]

Listen carefully. He says "There's one property of black holes that no process other than Hawking Radiation can decrease, that's the surface area of a black hole. Do anything to black holes, and their total surface area can only grow or stay constant." The key words here being "other than Hawking Radiation" and "total surface area". This means that aside from Hawking Radiation effects, anything you do to a black hole, will always increase it's total surface area, even if the total mass goes down. For example, you have two merging black holes- the total area of the merged black hole will be the sum of their individual areas, however the total mass of the merged black hole will be less than the sum of their individual masses, and that is because of factors like gravitational radiation and the penrose process.

[@Tomatoffel]

ah ok ty ray.

[@martalaatsch8358]

I just realized when this video was made, we didn't have that picture of an event horizon yet

[@ImageJPEG]

“The second law’r of thermal dynamics.”

[@DuctTapeRapist]

I spend all day in physics classes, and I watch spacetime when I want to relax.. guess I'm just a work nut

[@disculpa]

I've been wondering this forever. Thank you for the video

[@ZomBeeNature]

My entropy leaked out... even when I tied strings around them... 😢

[@TheHellogs4444]

Mind = blown. This has given me so much. I love this. I want more.

[@DavidBeaumont]

God damn that's deeply unintuitive. I can bound 2 volumes of space with 2 areas and then combine the to get a space with 2x volumn but < 2x bounding area. Meaning that there's < 2x the information in the new space. o_O And what if I have a "fractal" surface bounded by a simple sphere? The inner volume would be able to contain an arbitrarily high amount of information, but the large volume around it would hold less information ? I must be missing something...

[@DeathBringer769]

Now think about how the reason the human brain has so many folds is simply to increase the surface area while keeping the volume the organ takes up in our skull mostly the same. All that extra surface area helps us think a lot easier, helps us store more "information" in the same(ish) volume. If you could make the folds infinitely smaller and smaller you could theoretically hold more and more information on there approaching infinity. So yea, a simple larger sphere bounding a more complex "folded" object would be like you're describing: with the "smaller" object actually being able to hold more information. It's about purely surface area here, not about volume (and no, I'm *not* claiming the human brain works on the Holographic Principle. They are completely different. I only was just including it as an example of something else that benefits from "information" density going up as a result of the surface area increasing without needing greater volume, our skulls being analogous to the "bounded by simple larger sphere" you mentioned, as just a *loose example in general* for the concept of surface area vs volume vs information density geometrically speaking.) ;)

[@chrisbecke2793]

In terms of regular space, the surface area does not represent the amount of information in the volume but serves as an upper bound. If you combine two areas you get a space with 2x the volume, and a more dense representation of that volumes contents on its surface area. It turns out, as you pack more spaces together, if they contain enough "information" they also contain enough mass such that as the actual represented information on the surface approaches its maximum, the volume of the mass contained approaches that which is sufficient to self collapse into a black hole.

[@burtosis]

black holes don't work like regular objects. The surface area of a black hole is A=m^2(16πG^2)/c^4 where (16πG^2)/c^4 is constant. which means the radius is proportional to mass. In a regular sphere, if you make it 8 times heavier the radius doubles. Black holes the radius gets 8 times larger. Ignoring the energy of merging them gravitationally, if you had two of the same mass and joined them you will have exactly double the surface area. If one is big and one small, it will be more surface area than both added. It's not like merging bubbles but more of an area of effect.

[@Tfin]

The event horizon isn't bounding the mass, it surrounds it at some distance. All the matter within has left its entropy at the door.

[@burtosis]

Lol entropy coat check.

[@Danilego]

Wow, you guys made so many episodes that connect with this one, it’s almost like the MCU!

[@NewMessage]

That title would be a great band name.

[@sadderwhiskeymann]

nah, just enigma

[@Alex-tn7pv]

A 70's progressive rock band

[@aleksandrpetrosyan1140]

I’d like to elaborate more on “it doesn’t depend on charge or radius, but the surface area”, bit, that might seem confusing. In the Schrawrzschild metric, the radial coordinate is referred to as the area coordinate, as the space time and simply space warp enough so that a spheroid’s area is not linearly dependent on the distance, i.e. the Jacobian is a function of radius. So you describe the system using another coordinate, which is the square root of the area times a constant, and to confuse everyone, call it r.

[@kooky45]

How can a black hole have an electric charge that appears to the outside universe if photons are the mediators of the charge yet cannot escape from the black hole?

[@bormisha]

Those charged particles never actually fall below the event horizon for an outside observer. They stay outside, along with their field.

[@TurkeyMeat]

They can with hawking radiation although that may not be the reason why.

[@ObjectsInMotion]

It is not the reason why. Electric fields are mediated by virtual photons which can escape the event horizon.

[@TurkeyMeat]

Ah you're right

[@ThrottleKitty]

It's because electromagnetic fields do not need bosons interacting with them to exist. If you've ever dumped iron filings onto a sheet of paper with a magnet beneath, you'll see a series of lines. These lines of charge are always there, even if you can't see them, and nothing is interacting with them.

[@DoryenChin]

The whole idea that black holes can only have mass spin and charge makes them sound a lot like quantum particles

[@atrumluminarium]

That moment when physicists question the laws of Thermodynamics in favour of new theories Thermodynamics be like putting on its boxing gloves saying _"I'm not locked in here with you, you are locked in here with me"_

[@thstroyur]

That should be an Eddington quote/T-shirt

[@atrumluminarium]

It's a quote from The Watchmen so you can probably just find a shirt and swap out the face :P

[@thstroyur]

@Deadeye Spider Now you're thinking Oppie

[@mikejones-vd3fg]

if entropy is the giver and take of life , does that mean entropy created the universe?

[@alexandragrace8164]

this was AWESOME! And yay for Aussie hosts!

[@UltimateBargains]

I watched the entire video. I have one question. What?

[@JulianMoon]

These videos are fantastic!!! Thank you!

[@pronounjow]

Watching this channel is like developing a civilization's tech/research tree in a 4X or RTS game. Cool.

[@GuitarAndDiablo]

this is a really good video. so hyped for the next instalment on this series. keep it up

[@firelow]

Something felt off about the introduction. So I decided to check it out because I'm procrastinating. "Black holes seem like they should have no entropy. But in fact they hold most of the entropy in the universe. Let's figure this out. At first it seems that black holes are so simple that they should have no entropy. Well it turns out they contain most of the entropy in the universe. Let's see why." What happened?

[@ablebaker8664]

on approaching the vicinity of a black hole, the local traveler can still interact with the universe, but the closer the local traveler comes to the event, the more the travelers future interactions with the universe are reduced. The traveler observes the distant clock as ticking faster and faster until at the moment of his crossing the future of the universe passes in moment. The distant observer sees the traveler approaching the black hole and observes the traveler's clock slowing to a crawl. By the time the distant observer saw the traveler cross the boundary, the distant observer would also be witnessing the heat death of the universe. It doesn't matter that a black hole looks like a discrete object from outside. All a black hole is is a gravity well left over from a supermassive star. Whether you measure the decrease in heat/potential of the universe expanding and cooling, or whether you measure the decrease in heat/potential of matter falling into a black hole, they are both the same event. Falling into a black hole ends a particle's interactions with the universe. Space expanding also causes a particle to lose the ability to interact... and for a surprisingly similar reason. The universe is expanding. The further from any given point the faster it expands. That means that there is a distance (The Hubble Distance) at which a particle at that distance would have to travel faster than light in order to have any further possible interaction with the starting point... So, any point in 3D space appears to be the center of the observable universe. In 4D space however, the center of the universe, is its expansion front. In order to get to the center of the universe there is no path or speed in 3D space that can get there, but in 4D space any path is irrelevant except the direction backward in time. So... only by traveling backward in time can the entropy of the universe be reduced. Expansion and cooling are the opposite sides of the same coin. Okay... fasten your seatbelt Dorothy because we are now leaving Kansas. The image of a black hole from the 50's and 60's understanding can be tossed in the rubbish bin, because while it is true in 3D space, a black hole is 4-Dimensional... just as our universe is. Human beings didn't evolve in a universe where it made perfect sense that a phone booth can be bigger on the inside than it is on the outside, but that is exactly what a black hole represents. At the event boundary, the space time metric (the amount of distance between two fixed points in an expanding space) begins to increase at a rate greater than the speed of light... in 4D space the inside of a black hole is not shrinking, it's expanding. The further inward you go, the faster space is expanding. That essentially makes the expansion boundary of our universe indistinguishable from the space inside the event boundary of a black hole. To escape a black hole, and to find the event "center" of our universe both require going backward in time. Expansion in both cases appears to correlate with the direction of the arrow of time. Heat death doesn't necessarily mean the "end of time." It probably means the end of time in this universe, but the direction of time for black holes is not the same time... It is by no means certain, but it suggests that our universe is a black hole in some other universe, and that the end of a black hole in this universe, would take an infinite passage of time in this universe to occur, while a universe that might be a black hole in our universe, actually doesn't owe this universe a bit of mass or information more than the expansion boundary of our own universe... and the Hawking Paradox was never a paradox unless you tried very very hard to ignore the changes in the direction of time at both event boundaries.

[@MidnightBootySnatchr]

@@ablebaker8664 you just blew my mind

[@zorgius]

Able Baker wow, nice read, and all you have is a sewing playlist on your channel

[@Cavalorn12]

That was the coolest explanation of entropy ever.

[@PittooDesigner]

33 Views 69 likes, there's some unknown quantum mechanics properties happening.

[@user-be8ep2zd6r]

it is called caching. Something the nature doesn't use.

[@JS-fd5oh]

Just a simple time dilation

[@asterixgallier8102]

@@JS-fd5oh You mean a gravitational time idlation?

[@guilemaigre14]

Leonard Susskind beautifully explained that concept in one of his messenger lectures at Cornell. A must see.

[@recklessroges]

Pure math, 3 dimensions has the maximum platonic solids of any dimension, (implying 3d is special/zenith.) Physics: reality is 2d; 3d is a hologram/delusion of meat-space. Pseudoscience: we are all 1 with the universe. ;-s

[@MrSpikegee]

The idea that even black holes cannot destroy information is comforting. It helps me to know that my loving mother will always exist, encoded in the universe particles and fields quantum states.

[@solsystem1342]

33 views and 57 likes, seems legit

[@goheadfoehead]

Ender Bob 😂

[@Diggnuts]

Well, that would make sense in a universe that is a hologram I suppose..

[@thstroyur]

#BotLivesMatter

[@khatharrmalkavian3306]

This is definitely something worth fighting about.

[@JS-fd5oh]

Time dilation

[@VaradMahashabde]

I was kind of dreading the thermo and entropy they are a=gonna teach us this year, bu your videos now make me look forward to it :)

[@davids.2703]

"If black holes exist..."

[@JKDVIPER]

5:27 Just like or should I say much like the ADIABATIC changes we see here on earth. The shrinking of the stars core plus the fusion process being finished cause massive instant cooling and condensation.

[@TheZxcvbnm2100]

hi mom

[@inertialframe3424]

Honestly, Can anyone tell me the track name of the music playing at 8:04? @PBSSPACETIME whats the tracklist for this episode?

[@throwabrick]

Hi, I love this series, great coverage in both breadth and depth! I have been interested in Penrose's "Conformal Cyclic Cosmology (CCC)" theory since I saw him talk about it in a video. Now that he has published a paper claiming to have found evidence in the CMB for his theory... that there are features from a PREVIOUS AEON in the CMB... and that the clustering of them would seem to indicate gravity (or Dark Energy?) was different in The BeforeTime. Can you cover this. I can't think of a bigger story in physics right now. Once we have eLISA and other gravity telescopes online, we will be able to "see" back before the Dawn of Light... what are we likely to see, if there actually are features left over from an older universe? Also, I would really like you guys to cover Erik Verlinde's "Emergent Gravity" and Lee Smolin's ideas on the "natural selection of universes" and time NOT being an illusion. Also... Shape Dynamics? Cos it's really cool? And Transactional Interpretation of Quantum Mechanics.

[@redshiftedlight205]

The first video ever that's about the 2nd law of thermodynamics and not about the flat earth Also, the way you pronounced Gerard 't Hooft was hilarious, because I'm Dutch

[@zechordlord]

Great episode. It almost sounds as if it is some application of Gauss' law where an integral over a scalar field in the volume, translates to an integral over a its flow on the surface, but given the distorted nature of spacetime in a black hole I imagine calculating those is quite challenging.

[@CircusNarcissus]

You, my dear sir, are extremely talented !

[@davidwilliams9948]

Your channel is awesome!

[@demandred1957]

Outstanding episode as always.

[@conoroneill8067]

Can't wait for PBS to discuss String Theory. It's one of these concepts that gets talked about a lot, but rarely explained.

[@dejayrezme8617]

So as the information content in the universe increases, the universe also has to expand? Is that the reason why the universe expands? A kind of "information pressure" that defines the cosmological constant? Increasing entropy means increasing information content, right? Maybe this also explains the inflation period after the big bang? And does this have anything to do with the max speed of light or speed of causality? Somehow breaking the speed limit would break the amount of allowable information and reverse entropy / reverse time?

[@WhiteNucklin]

Highlight of my week. Thanks Time

[@semmering1]

This is so extremly excellent... Love it..