Physicist explains General Relativity | Sean Carroll and Lex Fridman
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- เผยแพร่เมื่อ 27 เม.ย. 2024
- Lex Fridman Podcast full episode: • Sean Carroll: General ...
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GUEST BIO:
Sean Carroll is a theoretical physicist, author, and host of Mindscape podcast.
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Guest bio: Sean Carroll is a theoretical physicist, author, and host of Mindscape podcast.
When Einstein published his theory of relativity, mainstream science considered Newton as god, the same way Sean thinks Einstein is god. Religion of Newton failed to predict Mercury's orbit and mainstream science eventually accepted Einstein's theory. Religion of Einstein cannot predict galaxy rotation curves, expansion of the universe, entanglement and quantum nonlocality but it is still the official religion of mainstream science.
Sean at his best. Some new and interesting facts about Einstein's gravitas. A stepped-up version of Lex, too. Good clip.
Einstein published 3 papers all in 1905 - Light as particles and not just waves, special relativity, and proof that atoms exist.
That's incredible, that's genius.
He actually wrote 4 papers. Professor Carrol forgot the most famous - energy/matter equivalence
e=mc^2
@@ShareTheMike But that's not in 1905
100 years later, in 2005, i shit my pants as a 6 year old.
He has a great voice. Carrol is one of the most respected science communicators and scientific theorists in his field.
Its good to 9.45- i sort of got it, then im out can someone explain the explanation
I like Lex, he's a very good interviewer
Lex's small hands makes this video better.
Thank you for crediting Minkowski
So special relativity is based on the Michelson-Morley experiment (1887), which found that the speed of light is the same for all observers. This seems ridiculous based on classical intuition, but once you've accepted it as confirmed fact, SR follows from it directly. Einstein's genius was being completely open-minded about following confirmed truths to their logical conclusions.
The motivation for general relativity is even older: It had been known since Newton's time that inertial mass (resistance to acceleration) and gravitational mass (mutual attraction of massive objects) are exactly the same. Again, from a conceptual standpoint, all Einstein had to do (in addition to the math of GR, which is much harder than SR) was clear his mind of traditional assumptions and find the theory implied by that simple, universal fact.
Nice shirt
Could someone elaborate on why it takes less time when you zig zag from point A to point B?
imagine yourself as a massless object on a flat spacetime whose "time" component is defined as the measure of events occurring. if, in the temporal dimension you zigged and zagged between the same two points, more events have occurred than if you went just "straight", ergo making the measure itself larger or in simpler words, slowing down time.
So a black holes emit radiation?
Sean Carroll reminds me of the dad in Happiness (1998)
Great movie, one of the best comedies of all time
Spitting image of that guy
Can someone explain to me why: over the last 50 years of studying black holes, we learned that the clock slows down as you approach the event horizon (go deeper into the gravity well). But nobody has proposed that there could be higher gravity potential energy "planes" or "dimensions" where the clock runs faster. Like a skyscraper where the event horizon is in the basement, we are in the first floor. The clock runs faster on the second floor, so that spaceships can move faster on the second gravitational floor or dimension. Maybe you have to get to the 50th gravity floor, where the clock runs 50x as fast, before you can think about using the 50th floor for interstellar travel.
I see where you’re going with that.. not bad
Theorem 7: The vacuum expectation value of the energy-momentum tensor in general relativity is proportional to the metric tensor.
Proof:
In general relativity, the energy-momentum tensor T_μν is a symmetric second-rank tensor that describes the density and flux of energy and momentum in spacetime.
The vacuum expectation value of T_μν, denoted by ⟨0|T_μν|0⟩, is the expectation value of T_μν in the vacuum state |0⟩.
According to the Einstein field equations, the energy-momentum tensor is related to the curvature of spacetime via:
R_μν - (1/2)Rg_μν + Λg_μν = (8πG/c^4) T_μν
where R_μν is the Ricci tensor, R is the scalar curvature, g_μν is the metric tensor, Λ is the cosmological constant, G is Newton's gravitational constant, and c is the speed of light.
In the vacuum state, the energy-momentum tensor vanishes classically, i.e., T_μν = 0.
However, in quantum field theory, the vacuum state has zero-point fluctuations that give rise to a non-zero vacuum expectation value of T_μν.
By the principle of general covariance, the vacuum expectation value of T_μν must be proportional to the only available second-rank tensor in the vacuum, which is the metric tensor g_μν:
⟨0|T_μν|0⟩ = κg_μν
where κ is a constant.
Substituting this into the Einstein field equations, we obtain:
R_μν - (1/2)Rg_μν + Λg_μν = (8πG/c^4) κg_μν
This implies that the vacuum energy-momentum tensor acts like a cosmological constant term in the Einstein equations, with an effective cosmological constant given by:
Λ_eff = Λ + (8πG/c^4) κ
The fact that the vacuum expectation value of the energy-momentum tensor is proportional to the metric tensor suggests that the concept of zero or nothingness may be deeply connected to the geometry and topology of spacetime, and may play a crucial role in the large-scale structure and evolution of the universe.
Can you explain this in layman’s terms?
curious, how much information does a black hole contain, just epically compressed.. The univers's "HardDrives"
(Event horizon area divided by Planck area) bits.
Cool idea
I think this gent is the bass-vocal in rockapella
How does quantum compare to corpuscle theory?
Corpuscular theories are still classical theories, so all of your intuitive understandings on motion apply to corpuscle. In quantum mechanics classical understanding of motion doesn’t apply. In QM we deal with the ‘motion’ of wave functions i.e how the wave functions change in time. The wave function contains all of the information we need to describe a quantum system, whereas there are separate functions that describe the information in classical systems.
@@FPSIreland2 that's a terrific answer
Comment section is bunch of people trying to sound smart saying stupid shit
Matter(s)=matter matters
It is odd to me that it is considered an accomplishment that they got rid of the aether, but then immediately replaced it with space-time and quantum fields. It seems like the aether never went away. They just got better at describing it.
"They just got better at describing it."
I think that's just science in general lol
there is no smallest jar
11:10 I’m so lost
Who created the universe and why?
Who created whoever created the universe and why?
You created universe to have 6 in it
@@Michael75579But who created whoever created who created who.
Infinite system. Something has always existed.
😂
Black holes fix entropy, no? Are things becoming more or less ordered as they cross the event horizon of a black hole?
Death is a black hole for the soul
Edgy comment. But I vibe with it
So beautifull
Birth is a White Hole for the soul. White hole is other side of black hole according to Roger Penrose.
r/showerthoughts
So when is Lex interviewing Terrence Howard? 😂
Maybe we r all living in a simulation, and the black hole is the program's equivalent of the PC trash bin. And EH is emptying the bin.
And the reason why black holes are so dense is bc of all the deleted files being accumulated inside the simulation's trash bin before it being emptied
The information problem doesn't seem terribly difficult. Quantum information is easy to conserve if it is fungible. I might never get my exact test particle back, but I can find one that has my particle's charge, and maybe another with its spin, etc. The only problem that might arise is if, somehow, the sum of the radiation is not equal to the sum of everything it ate. This has been neither predicted nor observed, and is unlikely to ever be. I think we're fine.
You can only proof a theory wrong but never right - feynman
Because God exists
Minkowski was a nut who deserves no praise. Recognition for coming up with spacetime as a concept, yes, but he was a zealot who hallucinated that space and time would forever be forgotten. That’s crackpot territory. Spacetime is a metric, nothing else. It isn’t real.
The earth isn’t flat
The Universe is Flat
I guessed
Time is law in motion...to be more exact...time is gods law in motion...all laws are created and have purpose and intention...they can't be broken..they can only be discovered. Time is those laws working...time ceases when laws cease....when a living creature dies,, all laws have ceased for that person..
They should make a movie about Herman Minkowski, then he might get the public profile he deserves.
I know that Lex Friedman was born in Moscow, but he totally looks like a love child between Joe Rogan and Belinda Carlisle. . . . Maybe Joe was at a GoGo's concert in 1983. 😅
A black hole is a star turned inside out.
Time is objective reality other than that it doesn't exist. There is movement, movement is affected by gravity.
How can a thing move without time? Without time, movement doesn’t make sense as a concept. Going from one place to another… but not being in both at once. You have to have time to have movement
@@Jm-wt1fsexactly, time is something we 😊believe is fundamental, its just the way we make sense of movement and the awareness of our mortality. aging, as a process is very apparent in humans. but, to your point, cellular degredation is part of motion and necessary to 3D. motion is the key
seems legit
I am so much dumber now after reading these comments 🤦♂️
I think Einstein’s greatest accomplishment was laying down the theoretical foundations of Lasers.
Which he did in 1917
I don't know why I don't like lex! Maybe it's the outfit
Postmodern sophistry
Are we not practicing black hole theories by stirring a cup of coffee with a spoon when mixing with sugar or milk or by cooking. Stirred,filtered and released.🤔 just asking?🤷🏾♀️
Mass creates a gap in spacetime, ez fucking definition
Falling to earth is space contracting with time
Define gap, what do you specifically by gap? To me a ‘gap’ in spacetime implies an area with no space or time.
@@lret2070 maybe he means dent or something
@@lret2070think of it like a ball in a pool. Freeze time and remove the ball. You see how there’s a hole where the ball used to be. Now the water is space time and a star for example is the ball.
Now the ball moves through space. Wherever the ball is in its place is the potential for that empty space to exist.
Hmm now if we could only find a way to have some sort of horizon like a boundary that exist with all the mass in a single point in that boundary. The left over space would be completely empty.
Now what’s the lowest field we know of. Zero point field. Well here’s the conditions for such a field. If only something like this existed.
Oh well I’ve said to much happy days
@@doomstarks182 I understand general relativity, my problem was with the word 'gap' being used and the person then acting like it was some intuitive explanation.
Bruh the other side is cool
Sean Carroll keeps talking with a strange inflection in his voice
And will not any seek any further insight
He needs to get high
It is rather frustrating to listen to
@deanodebo nah bro 🤣 close your eyes and it's Howard Stern 😂
I'm still with the doubters on Minkowski's contribution. Even in an outlandish world where 3D space emerges from some kind of cosmic brain or infinite-dimensional computerverse, I don't see how spacetime can be anything more than a mathematical convenience. I would put it up there with string theory in the category of physics being hijacked by mathematicians.
That was a pretty un-extraordinary explanation of general relativity. Perhaps good for people who already understand it.
Sean Carrol is regarded as one of the best science communicators in the world!!! And yes, this is neither a beginner's course or a comprehensive lecture... this is just a reply to lex's question
@@bluesque9687 Understood. But I think it would have been more valuable to give a more fundamental explanation. I think people like him forget how non-obvious this stuff is. :)
He claims Einstein didn’t understand black holes. Yes he did. He doubted that space could contain upwards of infinite density in a small area. Which by the way is still not proven.
He would hang around Amsterdam's Nigerian district
Yea. I’m gonna listen to you over Sean Carroll 😂😂😂
No, he claimed black holes were impossible several times. He even published a paper in Annals of Mathematics seeking to prove they were impossible. Black holes were not understood by Einstein, even though he laid the groundwork for understanding them through general relativity.
@@ballskin what makes you think he didn’t understand them? I’m missing your argument. You’re literally citing him addressing the issue.
@@deanodebo No, I said he thought they were impossible. Nobody fully understood them at the time, including Einstein. This isn't controversial. It's well-known. Black holes challenged some of the fundamental principles of general relativity, namely singularities. He thought they broke down the laws of physics as he understood them. His argument that they were impossible should be obvious enough. If your understanding of physics doesn't accommodate the existence of black holes, you don't understand black holes. Until the Penrose-Hawking singularity theorems (mathematical proofs that singularities are generic features of GR), Schwarzschild's solutions to Einstein's field equations, the Kerr metric, and other mathematical concepts like geodesic incompleteness and curvature invariants, black holes were not well-understood at all.
I cringe everytime I hear the words "space/time"
Why
@@polargeorge5872 because space has no properties. time is a measurement created by humans.
😂😂😂👌 so anyone can write a book now?
what do you mean by that?
@@campa6966 well I literally meant that I guess anyone who makes up anything in their own head can just write a book and then do a few paid interviews and all of a sudden it’s doctrine. Lol. Although I do enjoy listening to Lex Fridman, I found Sean Carroll to be redundant and a little uneducated when it comes to the subject matter, OK I’m kidding ,totally uneducated when it comes to the subject matter. But that’s OK. I guess he was left out of the gate kept peer group that we so lovingly and adoringly call the royal Academy of science.
Buddy, literally anyone CAN write a book. That’s always been the case if you can read and write. 💀💀💀
@@shaneperreault obviously. I do like the fact that that’s all you had to comment. It shows that you’ve never written a book. Lol.
So maybe a suggestion on who we should be reading on general relativity?
That's still not how you pronounce "Minkowski" correctly.
What's the correct way? MIN-KO-SKEE?
@@Picasso_Picante92Минковский
We pronounced it with American phonemes, so deal with it.
You guys obviously never heard about terryology
انَا اختكمَ مَن اليمَن وّالَلَه ماتكلمتَ الَا من جوّع وًّمَنَ ضَيَقَ الَحَالَ انَا وًّامَيَ وًّخَوًّاتَيَ تَشَرَدَنَا مَنَ بَيَوًّتَنَا بَسَبَبَ الَحَرَبَ نَحَنَ فَيَ حَالَهَ لَايَعَلَمَ بَهَا الَا الَلَهَ حَسَبَنَا الَلَهَ وًّنَعَمَ الَوكيَلَ فَيَ مَنَ اوًّصَلَنَا الَى هَاذا الَحَالَ 💔💔وًّالَلَهَ الَعَظَيَمَ مَا كتَبَتَ هَذا الَمَنَاشَدَهَ غَيَرَ مَنَ الَضَيَقَ وّالَفَقَر يَاعَالَمَ حَسَوّا فَيَنَا ارَجَوّكمَ وّالَلَهَ الَعَظَيَمَ رَبَ الَعَرَشَ الَعَظَيَمَ انَه الَاكلَ مَا فَيَ عَنَدَيَ بَالَبَيَتَ وًّالَلَهَ يَا اخَوّانَيَ انَهَ خَوًّاتيَ بَقَعَدَوًّ بَالَيَوًّمَيَنَ مَافَى اكلَ وًّالَلَهَ وًّضَعَنَا كثَيَرَ صَعَبَ نَحَنَ 6 نَفَرَ دَاخَلَ الَبَيَتَ وًّابَيَ مَتَوًّفَيَ وًّلَا يَوًّجَدَ مَنَ يَعَوًّلَ عَلَيَنَا وًّسَاكنَيَنَ فَيَ بَيَتَ اجَارَ لَانَسَتَطَيَعَ دَفَعَ الَاجَارَ الَلَيَ بَاقَيَ عَلَيَنَا ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' اخي اول كلامي انا اقسم بالله على كتاب الله اني لااكذب عليك ولا انصب ولا احتال اني بنت يمنيه نازحين من الحرب انا واسرتي بيننا ایت الشهرب 15 الف يمني والان علينا 45 الف حق 3 شهور وصاحب البيت من الناس الي ماترحم والله يا اخي انه يجي كل يوم يبهدلنا ويتكلم علينا ويريد من البيت للشارع لانناماقدرنا ندفعله الأجار شافونا الجيران نبكي ورجعو تكلمو الجيران ومهلنالاخره الأسبوع معادفعنا له حلف يمين بالله هذا بيخرجنا إلى الشارع رحمه واحنا. بلادنا بسبب هذا الحرب ولانجد قوت يومنا وعايشين اناوامي وخواتي سفار والدنا متوفي الله يرحمه ومامعنا أحد في هذا الدنيا جاانبنا في هذه الظروف القاسيه خواتي الصغار خرجو للشارع وشافو الجيران ياكلو واوقفو عند بابهم لجل يعطوهم ولو كسره خبز والله الذي له ملك السموات والارض انهم غلفو الباب وطردوهم ورجعو یبکو ایموتو من الجوع ما احد رحمهم وعطلة ردها لقمت عیش والان لوما احدنا ساعدنا في إيكيلو دقيق اقسم بالله انموت من الجوع فيا اخي انا دخيله على الله ثم عليك واريد منك المساعده لوجه الله انشدك بالله تحب الخير واتساعدني تراسلي واتساب على هذا الرقم 00967717415667 وتطلب اسم بطاقتي وترسلي ولاتتاخر وايعوضك الله بكل خير ساعدنا وأنقذنا قبل أن يطردونا في الشارع تتبهدل أو نموت من الجوع وانا واسرتي نسالك بالله لولك مقدره على مساعد لاتتاخر علينا وجزاك الله خيرا،.،.،:^:؛^:🎉°~°~^~°^π√^π√~π~√~√~π^~^~π~π~√√~~ππ~π√~~^^°^°€€لب🎉🎉❤❤🎉..............
Carrol has the voice of a hairstylist, a male ballet dancer, or a catholic priest if you get my drift
Heeee stretchessss outttt theeee lasttttt syllableeee offf hisssss wordssss
Your hearing things
@@michaelhicks8603 true enough. His voice for example
Yes, you’re being a weird homophobe because of your own insecurity
@@oneill765 he is a man, isn’t he?