As a student completing a PhD in theoretical physics (specifically physics beyond the standard model/quantum gravity), your physical intuition and ability to effectively communicate these ideas is truly inspirational. Please keep doing these videos!

48:50 Sean Carroll: "No one in their right mind will ever remember it". Also Sean Carroll: * Remembers it * Man you gotta love him 😄

@seandimmock5813

3 жыл бұрын

Adam Albilya I think he was reading it off his notes, but come on you still gotta love him.

Sean- thanks for so generously sharing this part of your life with the world, ( well at least this world).

@Wolf-ic1pd

Жыл бұрын

Thanks again … for sharing and allowing others to share their own healing insights and experiences with other aspiring Christian Scientists … God … good … guides … guards and governs the scientifically informed Mind … of the ever presence of divine Love both infinite and eternal … and likewise here and now … ❤ …

Another fascinating session with Dr. Sean Carroll. I can't emphasize enough how much I (we) appreciate your time and sharing of knowledge.

I get a incredible sense of excitement watching this video, Professor Carrol is such a great person.

Always wonderful elucidations, Prof. Carrol. Thank you for taking time to communicate physics in such a fantastic manner.

Sean Carroll is gold.

Great. Brilliant. Thanks again Prof. Carroll for another superb Q & A. Will watch it tonight and again in the morning. I have binged watched the whole series this week. (Well, almost.) That was FUN !!

Dr. Sean, I remember your lectures that I was listening to last year. Want to take a moment to say, Thank you~~~♡♡♡

Sean Carroll is awesome. The videos are definitely focused on novice (unlike Leonard Susskind’s lectures) but still wonderful! Thank you Sean

So, I want a "24 video course just about black holes"! (33:40)

I like the fact that even though Hawking didn't like the 2nd generalized law, in the end he believed in the two best known theories.

Thanks Doc. Great stuff.

Sean you are the best ever teacher I ever had in physics ... Thanks very much I wonder if you going to review the film TENET and the inversion of time...

Thanks, Sean!

40:47 The Penrose process. Since the object doesn't require to get close to the event horizon, it sounds like the process is not dependent on black holes. And then it looks familiar, similar to the gravitational sling-shot effect.

Thanks again for these brilliant videos. Ps minor fact check - Hawking's memorial is in Westminster Abbey not Winchester cathedral. It is where memorials to great artists and scientists are traditionally put in the UK; there is a prominent monument to Newton as well as many others.

02:00 the Principle of Equivalence. This is more of a inspirational tool to get you to think about spacetime in the limit, not to be taken as a deep down feature of reality. It helps you get to the top of the building, to GR, a deep down feature of reality, at which point you can throw away the ladder.

SUGGESTION - Dear Professor Carroll, “The Biggest Ideas in the Universe” is a genuinely excellent & inspirational video series, for interest, intellectual benefit & education. Would you consider releasing the whole series (after completion), as a set of DVDs ? This would be of special benefit to those people who are not always able to get on-line and access KZread. (Such as seafarers, for example.) I know that I would definitely buy the DVD set if it became available. I realise that DVDs may seem very out-of-date and Old Hat to some viewers, but they are still very popular with a significant number of the audience. Thanks again Dr. Carroll, and I hope you will consider this suggestion favourably. Looking forward to the next video.

@capoeirastronaut

3 жыл бұрын

You can get a KZread membership & download videos in the app

Thanks for doin, these videos ❗️

At some point I got lost, because I could not figure out any more how metric / connection and curvature behave as functions, that is, what kind of objects these functions take as input and what they send back as outputs. Maybe this would be easier to grasp for non mathematicians like me if it were presented using a sagittal representation ( explicitly stating the domain and the target set of the function). For example, when curvature is identified to a matrix, I cannot see anymore how it can be a function and what it "does" ( so to say). Anyway , these vidoes are absolutely unique and incredibly helpful! Merci à vous Pr Carroll !

Wow, never thought Hawking radiation would be overpowered by micro wave background

@SkorjOlafsen

3 жыл бұрын

You need a black hole about the size of the moon for the two to balance. Anything smaller will explode before very long, anything larger will grow from background radiation faster than it shrinks from Hawking radiation.

Equivalence Principle, Symmetry, In variance are aspects of the laws of nature. Maldacena introduced another aspect called 'duality' (ADS-CFT) as another law of nature, so as Sean explains entropy S is very high and very low for a BH, temperature T is very high and low, time similarly is high and low, information is lost and not lost etc., viewed from inside and outside of the BH, may explain the true nature of BH.

Requesting a book from you with all the topics in this episode.

At 52:00 and just before, you give the lifetime of an astrophysical black hole. Is that taking into account the cooling temperature of the CMB? Or is that as if it were in a zero-K context? A BH that doesn't eat will still grow as long as the CMB is higher than its own temperature. Then, what is the curve of the falling CMB temperature? If it's above the BH temperature due to evaporation, then the in-situ evaporation will be pegged to remaining in equilibrium as the universe cools.

@Dongufo15

3 жыл бұрын

BH have negative specific heat so the equilibrium would be unstable and with the slightest fluctuation the BH temperature would go above the CMB's starting a runaway effect.

I know I will sound like a terrible pedant, but 48:45 it's Westminster Abbey (between Newton and Darwin). This is a wonderful resource for anyone remotely interested in what modern physics has to say about the world.

@paulc96

3 жыл бұрын

That's right Steve. For those who don't know - Westminster Abbey is in London, whereas Winchester Cathedral is in the city of Winchester.

But Professor Carroll in his book on p.320 does mention and have a problem on the Lense-Thirring effect.

Two questions regarding the Time Symmetry talk in the video for White Holes: 1) Before the formation of the Black Hole, at an earlier time on the graph when the star collapses, isn't the Supernova like a White Hole? There'd be a section where nothing can enter it, and the explosion ejects matter from the centre of the star - opposite to the Black Hole. 2) If you extend the graph, such that R is the radius of the entire Universe beyond the observable Universe, the Black Hole in that scale is where everything is accelerating towards, analogous to a 'North Pole' (if you consider the Universe slightly curved like the Earth). And in the earlier time on the graph, the White Hole is a Big-Bang like explosion near the time of creation, leaving the 'South Pole' of such a curved Universe - a larger version of the Supernova from Q1. On this larger scale, you'd get Time Symmetry as well.

I love the part about the book: Singularities in GR!!

I saw an episode of "60 Symbols" explaining that a new paper explains the Information Paradox. But, his presentation is not elucidating. As of the making of this video, you should have known about this advancement. So what's up?

@Dongufo15

3 жыл бұрын

as far as i know there is more than one way to resolve te paradox, either giving up the "no drama" at the event horizon firewall style; or locality like in the ER=EPR conjecture, which is what leads to the little whormholes cited at the end of the video.

@fredrikekenborg4112

3 жыл бұрын

01:08:30

i hope to see in the near future a series on various speculation about quantum gravity

@timjohnson3913

3 жыл бұрын

Sean has a long solo podcast episode on quantum gravity (it’s on KZread as well)

@timjohnson3913

3 жыл бұрын

Sean has a long solo podcast episode on quantum gravity (it’s on KZread as well)

Time-Symmetry implications. Suppose that reality is time symmetric. The BB happened both ways in time. We "see" a universe collapsing over time to the (1) size -- the smallest possible size, perhaps with a non-uniform distribution of energy. The denizens of the negative-time universe experience entropy away from time 1, too. They, too, see, using their time direction, a universe collapsing into (1). There just is no time 0. The universe likes cause-effect. Okay each causes the other. Interesting questions arise if the directions in time are more than two. These directions are, IMO, probably QM probabilities.

Awesome. !

Whoa -- I think i'll need enter into review.

I love this series but it would be better if Sean says goodbye in each video, otherwise at the end it seems like if something is missing :o)

@remogaggi82

3 жыл бұрын

I like how he says "let's go" after his monologue. It's inspiring to me

@hokiturmix

3 жыл бұрын

On facebook it is rare when i start with hello and end vith good bye. If i turn into preaching mode to explain something to my mother or a friend i usually write The End at the end. With so many freinds we get to the point but if we cant get to an agreement of a meeting we don't apologize or anything... no need :D In science there is no final proof or argument :D

@jonathansharir-smith6683

3 жыл бұрын

@@remogaggi82 Agreed, I love that too. If you find that "let's go" particularly endearing, try his podcast (Mindscape) which is fantastic as well. He says it to begin each show!

@remogaggi82

3 жыл бұрын

@@jonathansharir-smith6683 I watch everything he does :) love me some Sean carroll

How can a BH have a measurable charge? Given that EM force carriers are photons and therefore cannot go beyond the EH. Is the charge entirely contained just above the EH? In that case doesn’t gravitational red shift reduce the effectiveness of the charge?

do BH really have charge? or is it just seeing the spin friction with the compressed space/time. and the charge building on the horizon? vs the actual "charge" of the hole. the hole itself has spin, and mass. EM and etc is the friction of space and matter falling into the hole.

Once you pass the event horizon of a black hole, it's not that you can't escape, it's that you won't escape because all your futures point toward the singularity. The light cone representing your future only points toward the singularity and no longer outside the event horizon. Does that sound right?

You explain the subject very well and it requires me to repeat a video hardly 2 or 3 times to understand fully. Thanks for your effort. I get confused that GR says that gravity is not a force but a warping of space-time Whereas while explaining Supernova explosion, it is explained with gravity as defined in Newtonian Physics. Similarly escape velocity is calculated (at least in most of the textbooks) using Newtonian Gravity, even the potential energy is also defined using Newtonian definition of gravity. I am searching for books or articles or video where These are explained using GR. If you find this is worthwhile, Can you please take this as subject in one of your video

Sean, following 35:47, does that imply that the entropy of black hole by itself is lower compared to, say, Jupiter? In your black hole video can you please cast a light on what is going on with the entropy of a black hole - Jupiter system when the prior swallows the latter?

@dimitrispapadimitriou5622

Жыл бұрын

No, even a typical small / medium size black hole has an entropy that is many orders of magnitude larger . Roughly speaking, the number of all possible configurations of matter ( of the collapsed star e.g.) that correspond to the final state of a black hole that has a specific mass, angular momentum ( and perhaps, charge ) is tremendously large, so the entropy of a black hole is way larger than any other astrophysical object ( like a star alone or a planet etc).

For the sake of the future of physics, I think, there is much guidance to be drawn from the fact that in the field of time nature exists as a duality. In view of this fact, a singularity is a useful device, and there is reason to believe it is only half the story.

So the singularity is the moment time stops for you? (Or rather for the elementary particles that were you)

What about something involving the holographic principle as far as a solution to the information loss problem? Is that seriously respected as a possible idea, or is it too much of a departure from our current understanding?

I think CCC likes it when entropy is reset by the evaporation of a black hole.

39:45 or so - the area theorem. Even throwing "negative mass" into a black hole would still increase the area, as it's proportional to the mass squared. You'd need to throw imaginary mass in, which might be a tad harder.

@dimitrispapadimitriou5622

Жыл бұрын

Nope. "Negative mass" will decrease the horizon area! For further details, look for Hawking's area theorem in conjunction with energy conditions and black hole thermodynamics.

@davidgould9431

Жыл бұрын

@@dimitrispapadimitriou5622 I knew I should have spent more time looking into it. Thanks for the pointers.

As a chemist, I know of course that ethers are very real and a bugger to break up. 1:09:00 I now envision a number of theoretical physicists torturing a black hole and saying "we have ways of making you talk!"

Regarding No Hair: Suppose you fed a black hole with baryons, blue quarks, or leptons. Would you then need to label the black hole with conserved quantum numbers like baryon number, color charge, or lepton number as well as mass, charge, and spin? If not, where did these conserved quantities go? Is this related to the information paradox?

@JohnDlugosz

3 жыл бұрын

My understand is that the conservation rules are relative to the types of interaction. Baryon number is *not* conserved by the usual electroweak interactions due to quantum chiral anomaly. Though that's never been observed to happen, it (or something else that violates it) was presumably important in the energy levels shortly after the Big Bang. I don't know how you'd get a BH to swallow an isolated blue quark, since that would mean leaving non-white color charge behind in the regular universe as well. Since BH does show electric charge, it might show other kinds of charges but the point is moot. But, gravity doesn't preserve baryon number. You could convert matter to anti-matter by harvesting the anti-matter from Hawking radiation and throwing the matter back in. Conversation of baryon number or lepton number is not like conversation of energy and momentum. The latter we expect to to be universal due to deep principles. The former are simply that we've not seen any process that changes them. Even the "deep" stuff gets funny once you include the bending of spacetime -- if space is non-Euclidean, you can rotate your momentum vector by carrying it along a closed path, and in GR conservation of energy is not well defined except in special cases.

Ok for a spinning black hole wouldn't the angular momentum exceed the actual physical integrity of the black hole? In other words spin so fast it overcomes its own Gravity and rips apart?

A question I always had is, if there is no preferred velocity, then how could there be centrifugal force due to spin. Is there preferred spin but no preferred velocity? How is that possible?

@bozo5632

3 жыл бұрын

If the spinning object has a radius, in other words if it isn't infinitely small, then different bits of the object, at different distances from the center, experience different amounts of centrifugal force. The bits are continuously accelerated, so they're not in an inertial frame. So you can tell whether you're spinning, even in Einstein's windowless room, because you can detect forces / acceleration. If you knew the exact masses and distances and forces of all the bits, you could calculate how many revolutions per second you were spinning relative to yourself without reference to external objects or any preferred frame. So it's different from inertial motion, which you can't detect or measure without an external reference. There is a minimum spin of zero, where no centrifugal forces are detected, but there is no equivalent minimum velocity. If you arbitrarily say that any object has a velocity of zero, and then you would measure the apparent (relative) motion of all other objects in relation to that object. But there's no equivalent way to say that one object is not spinning and everything else is spinning in relation to it, the forces won't add up. Unless maybe you do it in higher dimensions, IDK, it hurts my head to think about.

GWAN SEAN!

Another serious question, Sean. If I can create information by writing a book, but I can't destroy it by subsequently burning the book, which implies that the total amount of information in the universe increases with time, is information somehow related to entropy?

@timjohnson3913

3 жыл бұрын

I could be wrong, but I don’t think you are creating information by writing a book. You might be reducing a tiny amount of entropy (i.e. increasing order) by writing a book (life itself is a pocket of order), but on the whole, the universe is still increasing in entropy no matter how many books you write.

Isn't the conservation of information postulate just an axiom and not a theorem? I.e. it's a speculation that hasn't apparently been disproven, but to think this idea applies to black holes, etc. seems a stretch that does keep a segment of the theoretical physicist population busy.

Love listening to your explorations...imagining if the universe was an infinite ocean with consistency as liquid or jelly substance, with all elements moving within it causing curvatures, variety of formations depending on size, distance and impact......seems incalculable challenge of it's totality!

1:43 "when the wise man shows the moon, the fool looks at his finger" 😅

Isn't quantum teleportation a way to create a perfect copy of something?

13:20 - But why are they equivalent?

A whopping good romp around the block... there's a zillion good ideas in this video. Really good job Sean. Here, let me solve the info paradox for you... Information doesn't really exist anymore than "fourteen pi r squared" exists. Info is just one of those mythologies people made up because we are all inherently story tellers. It's a real as Zeus or Teenage Mutant Ninja Turtles and it's loss is not a meaningful concept. So there ya go :))

Maybe there is no singularity. Perhaps all 100% of the mass that made up the star was converted to gravity in some as of yet unknown way. So if that's true then perhaps the event horizon is the only physical thing that remains of the original star.

Why is it necessary to speak about the charge of a black hole? I understand mass and spin because those properties are visible outside the event horizon. How can one speak about charge when the charge cannot be measured from outside the event horizon? (or can it? If so : How can the electric field escape from the black hole?).

Well, but after all, do they really exist those Big Monsters we call BH? Or are them only our trivial but fancy speculation about something we should be IN PRINCIPLE ignorant? (Hic sunt leones, but then eventually some new more accurate map of the world may came...)

I'm probably going to get fussed at for all these dumb posts but in regard to Hawking radiation here's a thought: I call this Hawking radiation paradox: If time runs faster outside the event horizon of a black hole than it does inside the black hole, Hawking radiation would evaporate the black hole before enough time has passed inside the black hole for such an event to have occurred. So how is it that a black hole could experience two frames of reference at the same time? There seems to be a real paradox here. If an observer inside a black hole looking out could survive long enough, could she witness hawking radiation evaporate the black hole before enough time in her frame of reference passed for the evaporation to occur?

Come on Sean, Boltzmann got more than a little sad, he killed himself. Left his formula on his headstone.

Can you define the term "manifold"? Many thanks

@benwincelberg9684

3 жыл бұрын

A shape (but could have any number of dimensions)

Sean, serious question: can't the Big Bang be thought of as a "white hole" in the past of the universe?

@dimitrispapadimitriou5622

Жыл бұрын

The Big bang singularity ( if existed) was spacelike and *isotropic*: That's what observations ( e.g. from CMB) indicate. On the other hand, white holes, as Sean pointed out in the video, are the time reversed versions of black holes, so their initial singularity is *anisotropic*. In other words, the Weyl curvature, that has to do with tidal forces, diverges *initially* inside white holes ( just like it does *finally* inside black holes), but this is not the case for the beginning of our real universe! So the answer is No: white hole and Big bang singularities are very different in that aspect.

20:44 How exactly does that gel with the fact that an event horizon is, well, an event horizon? I'm sure a single particle wouldn't notice, but a large object such as a person with forces traveling all around it that has partially crossed the singularity would no longer be able to interact with itself across the horizon (and thus would not be able to remain a single coherent object held together by chemical bonding and van der waals forces and whatnot that is all mediated by the electromagnetic and photon fields that necessarily transmit information), would it not? I can't imagine how forces could keep something together across an event horizon without also necessarily transmitting information across the horizon, which should not be possible. Does this actually true for a large object?

@Dongufo15

3 жыл бұрын

if the object is relatively large compared to the BH radius the tidal forces will spaghettify and destroy the body. If you are trying to keep the object from completely falling in there will be two opposing forces that will stretch and break the bonds. If the body is simply falling no information will escape and leave the BH.

@hokiturmix

3 жыл бұрын

Small object small black hole Big object big black hole With big enough black hole a person won't feel the spagettification :D

@capoeirastronaut

3 жыл бұрын

Have a look at cosmological event horizons - which you are constantly passing through, in relation to different places in the universe all the time. Event horizons arevrelative, or 'as seen from -'. The black hole's event horizon is a feature looking /from outside/, where we would see time come to a stop at the horizon. But to the horizon-crosser the picture is different. It's the extreme case of time dilation, where time goes slower on a spaceship seen from Earth, but from the spaceship time there is normal, & Earth slows.

@Nosirrbro

3 жыл бұрын

@@Dongufo15 I understand that large black holes do not cause significant tidal forces in small objects, my question is specifically about the event horizon itself as any object passing into the black hole would, at least by my understanding, spend a non-zero amount of time only partially across it from its own perspective.

@Nosirrbro

3 жыл бұрын

@@capoeirastronaut Cosmological event horizons are relative to any given observer of course, but with the exception of high velocities causing objects to become 'compressed' from your perspective any given observer is going to agree on the schwarschild radius of a given black hole, including the top and bottom of some given object, no?

This whole series sets new standards.

@appercumstock3017

3 жыл бұрын

YT give him more money.

The equations around Einstein's guess and onward totally lost me. To quote, the British metropolitan middle class elite comedian, Stewart Lee, "like a dog listening to classical music".

@JohnDlugosz

3 жыл бұрын

Dog listening to classical music: "What's with these human speakers? Always losing the treble end." My parrot dislikes Bach for some reason, but likes Mozart OK.

If the smaller a black is the faster it radiates away there must be a minimum size limit of black holes in the universe, cause anything smaller would already have radiated away (unless of course they are being created today, and we see no evidence of that). If relativistic laws break down at the event horizon and quantum laws exist beyond wouldn't the relativistic information in your "book" break down also, or at least be captured or confined or spread across the event horizon.

If general relativity etc is a fundamental part of 'reality' ('Quantum' - thingness and 'quanta' - thinginesses) - then Einstein could not have invented it (or even discovered it). As a posited concept presented by him .. resting on the work or ideas of others, of course .. its maths fitted remarkably well with the earlier notions of 'time' as the relationship(s) marked by the (or, a) distance between two passing objects. Gravity, the weight or serious/ imperious majesty aka hefty power of attraction in the relations between material bodies, is, naturally enough, an abstraction from this observable force (i.e. power of attraction at work) specifically considered in terms of 'heaviness' (e.g. the ability to heave/ to have hove/ to be hoven/ to have been hoven) apparently governing two or more material persons/ bodies/ objects. See, it's that simple. Yeah! ;o)

@TheLeonhamm

3 жыл бұрын

@Road Runner Actually, to be pedantic, the stuff of Mechanics (of Quantum or quanta material) was built by no human hand or mind - being the underlying reality (aka substance and its working principles) of natural philosophy observed and considered, by 'us', in terms of the motions of more or less macroscopic objects. This science, for a genuinely empirical science it is, is concerned with the forces applied to or relevant to objects which result in displacements or other materially perceived changes of an object's position relative to its environment (i.e over 'time'). So I agree wholeheartedly, such knowledge can only be attained - or posited - by relying on the observations and presentations of others; and, mercifully, it would seem, the more we know the less we understand of what is now known .. not so much nescience as the product of the Via Negativa (a form of understanding still too often dismissed as 'metaphysical' - as, of course, indeed it does follow on after the Physics. Sorry to twitterate on. Thanks for the thoughtful reply. Cheers! ;o)

@TheLeonhamm

3 жыл бұрын

@ Indeed so; a truism is still true. No, the Thing at the start and the things that proceed from it, though organically one (thing) at conception, for instance, in growth, senescence and death, are rather different (things), in development and expression, at dissolution, in the end. Thus quantum anything (physics, mechanics, logistics) presents a distinct case in understanding and knowledge, quite other than the principles we perceive in the distinctive quanta somethings; so expecting that first (whathaveyou) to act like or even look like the abiding (whatsoevers) is .. umm .. a bit of a mistake. ;o) The Via Negativa helps us clarify such perplexities by setting out what (x - the object under consideration) is not - rather than noting the categorical difference between the idea of 'It' and the It that we actually observe.

Is it possible that Dark Energy is in fact caused by the rotation of the Universe?

@SkorjOlafsen

3 жыл бұрын

If it were, there would be more expansion on one side of the visible universe than the other, along the line towards the center of rotation.

@ovdtogt1

3 жыл бұрын

@@SkorjOlafsen You could assume our perspective is the center of the Universe, analogous to being in the center of a rotating disk in a 2d Universe.

Please define time in terms of mass.

Like a steak that was left on the grill too long. That was well done. Cheers.

Can time be ether?

If you've seen my office- you would know that books collapsing into a black hole is a real possibility.

They had hair in the 70s.