Special Relativity | Lecture 10

[@AT-27182]

These lectures are a gift to humanity. Thank you so much Prof. Susskind. Thank you Stanford.

[@ravinchoudhary7617]

So it is last lacture, i've seen all these video lactures in just one day, those guys who were in that class are very lucky, i had read somewhere 'if you want to learn something, learn it from the best'. You are a legend sir. this is june 2020 you gave these in 2012 at the age of 72, i appreciate your energy levels (now you are 80 😔😔) Thank you Stanford and Thank you so much Dr. Susskind 🙏

[@tritoncozy8354]

7

[@tritoncozy8354]

888888

[@MrAngryCucaracha]

Jesus man, the whole lectures are 18h.

[@muditchaturvedi5276]

@@MrAngryCucaracha People with interest and dedication can do anything !

[@santiagoerroalvarez7955]

Both this and the General Relativity set of lectures were absolutely fantastic. It's a privilege to have access to this. Huge thanks, Dr. Susskind!

[@massimoacerbis8138]

Standing ovation to prof Susskind

[@hasanshirazi9535]

Just finished watching this 10 lecture series on Special Relativity. Thanks Prof. Susskind and Standford.

[@henrywang6931]

Its been a great pleasure! I have learned so much! Thank you!

[@tommie997]

Yes! I prefer the chalkboard over the whiteboard just as much as I love Professor Susskind's lectures. People who say it's old fashioned are completely missing the point. More chalk! (and physics)

[@Akash_Tyagi_93]

GRATEFUL GRATEFUL GRATEFUL. Thanks Dr. Susskind Thanks Stanford.

[@joshrebholz237]

Hhhvvvhvhvvhvvhv

[@joshrebholz237]

H h to hh h. Hhhjh h. Hh hhhjh. Hh h h hh I’m. H h h hhh. Hhh.

[@joshrebholz237]

H h h h h h h h hhhj. H h hh h. H hh

[@joshrebholz237]

H h h h h h h h hhhj. H h hh h. H hh

[@joshrebholz237]

Hh h hhh hhh h hh. Hhh. Hhh. Hh h. Hh. H. Hh h hh. Hh. H.

[@laitailai]

Thank you very much ! Professor Susskind.

[@brainstormingsharing1309]

Absolutely well done and definitely keep it up!!! 👍👍👍👍👍

[@fsh3702]

This is really some wonderful and accessible explanation of some really difficult subjects.

[@pedroakjr2371]

i can't remember the last time I saw a class clapping at the end of a lecture.

[@abhinandan008]

Leonard susskind,I want to meet you.How amazing it would be to sit down with him over some bottles of beer.Great lectures,particularly the way you broke down the Energy momentum tensor and explained it with such ease.Thanks stanford for encapsulating those priceless lectures and for making it available to the general public

[@craigfowler7098]

Shows how intelligent Einstein was, he came up with this stuff from scratch!! I have a Physics degree and I am lost!!

[@sherlockholmeslives.1605]

+Craig Fowler I failed GCE Physics from school with an F.

[@Akash_Tyagi_93]

:)

[@sherlockholmeslives.1605]

I don't think Einstein was clever at all! Art Garfunkel is clever! Einstein was just that big-headed prick who through inertia thought that he knew better than quantum mechanics!

[@sherlockholmeslives.1605]

I'm a Very Clever Person!

[@craigfowler7098]

Yep I thought so as he is making stupid comments - e.g. how can he be a clever person, if he failed GCSE Physics and think that Art Garfunkel was more intelligent than Einstein!!!??!!

[@petergreen5337]

❤Thank you very much Professor and class.

[@notyourbusiness090]

Hey can you please tell what are the prerequisites for this lecture series. I know basic Newtonian mechanics only

[@physicsofphysics-sksamrat1309]

Sir, we love you

[@bibekgautam512]

Thank you 🙏 its been a pleasure!

[@qwadratix]

The move at @1:40 when he introduces Div.E by using partial integration is a bit of a cheat. He misses out something important. It only works if E.A is independent of x (the partial integration always includes a term given by d(E.A)/dx that he assumes to be zero). E.A is only independent of x (or any of the other spatial directions) if A and E are perpendicular. Since B=curl A that also means E and B must be measured perpendicular to each other. (This is why I lose track in lectures generally. My mind goes off at a tangent in such circumstances. I wish I could just take notes and think about it afterwards.)

[@markmetalen37]

During the last few year I 've enjoyed quite some of the online-lectures by professor Susskind, which have been made available by Stanford University. I have an undergraduate degree in physics so in some cases is has been a nice refreshment of theory that I didn't encounter for a while. I want to thank Stanford for this nice lecture series-project! Secondly I wondered if professor Susskind and his group ever tried to tackle some of theoretical problems regarding the systems that he's interested in, i.e. quantum-entanglement in extremely gravitationaly curved spaces (black holes, Einstein-Rosen bridges and such), with the help of Lorentz Invariant Theory of Gravitation (LITG) instead of General Theory of Relativity? I really feel that this idea should be dropped somewhere because it does indeed seem that LITG leads to the same results as GTR/GR whenever checked through experiments and it might work a bit better in combination with quantummechanics and quantumfield-theory due to the fact that it involves slightly less tensor 'action' and is easier to grasp (no worries, it contains enough tensoralgebra). I suppose that this went by somewhere at one point in time but I never encounter references to LITG in these kinds of lectures and talks.

[@NazriB]

Lies again? Better Than SAF

[@hellotoearth]

Exactly how does answering the question "why" shed light on the most important questions of all?

[@tommie997]

I'm not against expression of opinion, calm down. All I am saying is he is not strictly 'wrong' and it was ignorance on your part to assume so. Also I believe the question "why?" was in the context "why do we believe something to be so" -- asking for an elaboration of the theory rather than a reason as to why nature does something.

[@DrDress]

1:16:10 That was weird :-S

[@adamfattal9602]

It's because they were using iMove lol

[@massimoacerbis8138]

Most appreciated prof

[@tejasgokhale01]

Where can I get notes he talks about?

[@tejasgokhale01]

Ajay Rawat thanks Ajay!

[@ShivnarayanDhuppar]

Thanks so much! :)

[@massimoacerbis8138]

That is the third times I complete this course

[@ADITYAKUMAR-mb5ht]

Can anyone provide some materials for practising something regarding this topic

[@tungMJ1996]

LOVE STANDFORD

[@abhijithrambo]

At 1:39:15 , we can set An to be vanishing at infinity by setting ds/dXm (Gauge factor) to the required value. But since we already used that freedom to make A0 to be zero at the start of analysis, is that integration valid ?

[@qwadratix]

No he didn't. Infinity doesn't come into it. He observed that the expression is div.E, which is zero in charge free space.So the second part of the curl expression that he wants is necessarily zero - so he can insert it for free. It changes nothing. It's a rather elegant proof. It took me quite a while to wrap my head around the fact that he can define the potential out of existence like that! (Not really - it's just the definition of A and the freedom of the gauge change allows an amazing degree of mathematical flexibility)

[@evielily7350]

Meanwhile me at joinor high reading these comments 🥶😳

[@frankdimeglio8216]

@@qwadratix The ultimate unification and understanding of physics/physical experience combines, BALANCES, AND INCLUDES opposites, AS E=MC2 is CLEARLY manifest as F=ma ON BALANCE; AS ELECTROMAGNETISM/energy is gravity. Here's the proof. This also explains why objects (including WHAT IS THE FALLING MAN) fall at the SAME RATE (neglecting air resistance, of course), AS E=MC2 IS CLEARLY F=MA ON BALANCE; AS ELECTROMAGNETISM/energy is gravity. TIME dilation ULTIMATELY proves (ON BALANCE) that E=MC2 IS clearly and necessarily F=ma ON BALANCE, AS ELECTROMAGNETISM/energy is gravity. Gravity is ELECTROMAGNETISM/energy ON BALANCE. ON THE CLEAR, EXTENSIVE, SENSIBLE, BALANCED, THEORETICAL, AND UNIVERSAL PROOF THAT ELECTROMAGNETISM/energy is gravity, AS E=MC2 IS clearly PROVEN TO BE F=MA ON BALANCE: Balanced inertia/INERTIAL RESISTANCE is fundamental, as ELECTROMAGNETISM/energy is gravity. The stars AND PLANETS are POINTS in the night sky. Energy has/involves GRAVITY, AND ENERGY has/involves inertia/INERTIAL RESISTANCE; AS gravity AND ELECTROMAGNETISM/energy are linked AND BALANCED opposites; AS ELECTROMAGNETISM/energy is gravity; AS E=MC2 is CLEARLY proven to be F=ma ON BALANCE. This NECESSARILY represents, INVOLVES, AND DESCRIBES what is possible/potential AND actual IN BALANCE. Indeed, A PHOTON may be placed at the center of what is THE SUN (as A POINT, of course); AS the reduction of SPACE is offset by (or BALANCED with) the speed of light (c); AS ELECTROMAGNETISM/energy is gravity ON BALANCE; AS E=MC2 is CLEARLY F=ma IN BALANCE !!! Gravity is ELECTROMAGNETISM/energy ON BALANCE, AS E=MC2 is CLEARLY proven to be F=ma IN BALANCE. TIME dilation ULTIMATELY proves (ON BALANCE) that ELECTROMAGNETISM/energy is gravity, AS E=MC2 is CLEARLY F=ma ON BALANCE. Gravity/acceleration involves BALANCED inertia/INERTIAL RESISTANCE, AS ELECTROMAGNETISM/energy is gravity; AS E=MC2 is CLEARLY F=ma ON BALANCE; AS the stars AND PLANETS are POINTS in the night sky. Accordingly, ON BALANCE, the rotation of WHAT IS THE MOON matches it's revolution. TIME is NECESSARILY possible/potential AND actual IN BALANCE, AS ELECTROMAGNETISM/energy is gravity; AS E=MC2 is CLEARLY F=ma ON BALANCE. The stars AND PLANETS are POINTS in the night sky. Accordingly, ON BALANCE, it makes perfect sense that THE PLANETS (including WHAT IS THE EARTH) will move away very, very, very slightly in relation to what is THE SUN !!! ELECTROMAGNETISM/energy is gravity, AS E=MC2 is CLEARLY F=ma ON BALANCE. Inertia/INERTIAL RESISTANCE is proportional to (or BALANCED with/as) GRAVITATIONAL force/ENERGY, as this balances gravity AND inertia; AS E=MC2 is CLEARLY F=ma ON BALANCE; AS ELECTROMAGNETISM/energy is gravity. GREAT. I have explained the cosmological redshift AND the supergiant stars. Stellar clustering ALSO proves ON BALANCE that ELECTROMAGNETISM/energy is gravity, AS E=MC2 is CLEARLY F=ma IN BALANCE !!! By Frank DiMeglio

[@Darfail]

I'd rather have a prof who records his voice and posts the class notes, like my Modern Physics teacher does right now. Of course, having the video is the best of all worlds...still, I like digital better than chalk.

[@pconstantino201]

We've called too many things "p", lol, I love susskind

[@KipIngram]

20:00 - Wait a minute - I don't get that. It sounded like he said that the conserved quantity (the momentum was PROPORTIONAL to the infinitesimal shift. But that could be anything - it's arbitrary. What's up with that?

[@AT-27182]

For more information on this, maybe this could be helpful: The section entitled "Brief illustration and overview of the concept" on the Wikipedia article "Noether's theorem". The rest of the article discusses the details. (en.wikipedia.org/wiki/Noether%27s_theorem#:~:text=As%20an%20illustration%2C%20if%20a,of%20its%20laws%20of%20motion.)

[@chayanaggarwal3431]

You should see nother's thoerm on wikipedia but it's something like this - for example you have a quantity say energy and want to know if it's conserved or not you could see the generater of the quantity if the generater of the quantity is symmetric about its infinitesimal generation then the quantity is conserved it's a little bit complicated so better see the wikipedia

[@MrAngryCucaracha]

If x is conserved, so is x times a constant. Because the constant is by definition always conserved.

[@hellotoearth]

A simple swap of the two!

[@tommie997]

It's called Rayleigh scattering, he was right, he just didn't explain it in enough detail. And the "why" is left open to interpretation because none of us can prove otherwise but using common sense he probably didn't expect Susskind to tell us why nature behaves the way she does because everyone knows that's impossible. Don't be offended btw I was talking in general in my first statement not just about you.

[@hellotoearth]

Also, the air does not "appear blue," but the quantum effects of re-emitted photons from the excitation of particular atoms allows for particular wavelengths.

[@sabrewolf479]

42:17 He confuses Hamiltonian Density with the summation of "i" Canonical Momentum Conjugates. See en.wikipedia.org/wiki/Hamiltonian_field_theory for the correct expression and derivation.

[@Tunatunatun]

So close, bro. You missed that ray scattering is inversely proportional to wavelength! XD Then blue (small wavelength) scatters more than red (long wavelength), and so on with sunset. But the explanation is right!

[@Tunatunatun]

I wasn't even trying to... Don't take every comment as an offense, I was trying to be constructive to your point by adding the RIGHT WAY to make your ideas work. But now, I'm not only not on your side because you rejected my help on your discussion, I am now against your short-minded inability to understand the concepts properly to make a valid statement, and I'm probably thinking you don't know much about physics. If you had, you'd have just been happy I corrected the only mistake you had.

[@ivanrango]

Muuuy capo Leonard! clap clap clap

[@littlewhitebutterflies4586]

I think physics would be easier with the chinese alphabet. You'll never have to use the same letter twice lmao

[@RobeonMew]

Is this professor also a parking attendant for a law building?

[@hellotoearth]

Still wrong. Visible light is passes through LESS atmosphere (nitrogen and oxygen atoms) when the Sun is directly overhead or higher in our sky, thus, we see the longer wavelengths (blue). Photons of visible light travel through MORE constituents of our atmosphere as the Sun dives lower on our horizon, thus, we see that only the shorter wavelengths (reddish orange) are able to pass through the thicker patches.

[@Tunatunatun]

Dude, why do you have to think I'm angry and attacking you? I was saying that you were just wrong when you said blue light has long wavelength and reddish orange has a low wavelength. It was the only thing wrong and I just put it right so the other dude couldn't correct you. Peace, man.

[@hellotoearth]

You missed the point of the question completely.

[@redrum41987]

1:17:30

[@patriciaheil6811]

it's all the same thing == "it's still rock and roll to me"

[@zxrxrichter4471]

🙏

[@hellotoearth]

Oh, and you got the answer to the how wrong as well.

[@aaronramen5926]

This is where the lecture ends.

[@Tunatunatun]

HEY, EINSTEIN I'M ON YOUR SIDE! - Falco

[@tommie997]

Are you sure that reddish orange is of shorter wavelength than blue? Which according to you has longer wavelengths? Hahahaha, you have proved my point!

[@zphuo]

20180515 Thanks Dr. Susskind...

[@satyaprakashjoshi1837]

why these students keep bugging him on sign........... come on; -1 is scaler just fix it whenever you feel your equation aren't matching with "notebook"

[@shiddy.]

in Crayola

[@supersopamop73]

way, way ovr my head. perhaps one day though

[@abhijithrambo]

did that one day happen? :)

[@AverageGaming101]

@@abhijithrambo lol

[@Hub632]

Susskind must have had a bad day. This lecture is much less comprehensible than the other 9. He looked a bit impatient.

[@jqahremani]

👏👏👏👏

[@shrook2257]

2021👽👽

[@tommie997]

It's not 'wrong' just not detailed enough... I hate how everyone on these videos are so arrogant and believe they are intellectually superior just because they are watching a physics video, funny thing is the majority of people here have no idea what he's talking about haha.

[@JamesCarmichael]

I so wanna understand it too lol.

[@hellotoearth]

Well, there's no way I'm going to argue on how many levels the answer was incorrect, because it seems that I'd be laughing at a stone wall. And, again, there is no answer to "why" anything is unless you have proof for the existence of a human-like entity which had a definitive purpose in creation - an unanswerable, philosophical question. Hint: We don't even have evidence that god exists, let alone able to understand the philosophy behind the god's reasoning.

[@stupidpdj]

I lost lots of signs.

[@hellotoearth]

No, he was wrong. And whenever you ask the why you are assuming there was a purpose intended and therefore a god which gave a particular reason for the way nature was put together. Please ask a philosophy instructor on this subject so you can be further educated on the differences.

[@hellotoearth]

How does this further explain anything more? You've just described what I already have but in different words and tacked on a measuring equation to try your hand at looking half intelligent. Sorry bro, you've failed at making me look silly.

[@جحخخحج-د9ص]

الترجمة رجاأ

[@РодионЧаускин]

Hall William Taylor James Young Jason

[@craigfowler7098]

So obvious!!!???!!! LOL!!

[@sherlockholmeslives.1605]

Craig Fowler Did you know that the memory is like a block of wax, you can mark it with a stick which leaves marks and overtime these wear away but new marks can be made in it. 'The Wax Tablet Hypothesis' by Plato ( 429bc - 347bc ). More recently memory has been understood to be to do with DNA. I like the first idea though as I can understand it. Both explanations are interesting pieces of scientific thinking!

[@hellotoearth]

First off, it's not that I feel higher up on the IQ scale than anyone viewing this video, because I'm not. It's that those whose view I'm taken back upon force me to show my opposing view back at them. If expression of opinion shouldn't be heard then I suggest you reason with KZbin to start censoring negative feedback. By the way, arrogance is not only found in videos relating to science :)

[@hellotoearth]

Sounds to me like someone has a severe case of intellectual pretense. 'Knowing' anything related to cause and effect in the natural world is never a matter of asking the question "why," because the question itself refers to a reason. As far as science is concerned, nothing in nature acts upon the base of reason, but simply acts the way it acts because it is the way it is. It's like asking why the sky is blue. There is no answer; it's strictly philosophical and worthless.

[@hellotoearth]

You just answered the question how it is, not why it is. Try again, genius.

[@hellotoearth]

Come now, you had no point to begin with :)

[@hellotoearth]

I take no offense, however, you seem very confused and misguided in your logic.

[@newtonrhodes7093]

Religious scholar. Teaches theories. Believes in the astro part of astrophysics. Believes in evolution. Smart in useless and scary educator sort of way.