Some insight into Einstein's Theory of GR

Nice Demonstration though not an accurate simmulation of GR

[@KishanLovesAstro]

Sir I found this video as a short but I didn't saw the full video. By the way thank you so much !!!!

[@ketansharmag1]

Sir i didnt knew nothing about theory of relativity. I only knew name of it and also that it is given by einstein but after watching this video my mind is blown up and gets more interested in physics. Thanks ❣

[@Sciencebuff0003]

Almost all the lectures l have seen and now I am preparing for physics Olympiad. Thank you a lot sir. Physics is ❤️

[@Piyushvaksh12]

Sir your explanation is amazing, really loved it

[@1275karie]

Thank you for the visualization of this theory. This made way more sense. ❤

[@fruityrazzmatazz9183]

Hey wonderful demonstration, thank you for sharing. One question that comes to mind, when a star goes supernova, does its gravitational field become limited or reduced?

[@nthumara6288]

sir i am very interested in physics and this week i am having a interviw for a physics special degree.i have wached all most evey lecthers of you. and i want to thanks for all of the help you provided for lerners like me.thank youuu so much sir

[@Folorunsho3729]

please I have a question, since time runs slower on Jupiter due to its gravitational force compared to Earth's time. if Earth and Jupiter were to be placed side by side and an observer in each of them to measure the time it takes for sunlight to reach them. since the light will travel the same distance and it takes 8mins for it to reach Earth, will the time measured by the observer on Jupiter be less since time runs slower on it? that is, will the time in the internal clock of the observer on Jupiter be less?

[@boramordo1554]

Thank you. This is a very good illustration.

[@JohnSmith-xn3fr]

And why doesn't the orbiting planet crash into it's star ?

[@sifatahmed1413]

Same question

[@in-diaonic3391]

This demonstration is taking place on the Earth. It's the EARTH's gravity which causes the smaller ball to collapse into the heavier ball. This isn't the case for outer space. So if the object has sufficient linear velocity it will be captured into the orbit of the star and won't collapse into it.

[@avneet5665]

It's because planet also has gravity, planet also pulling stars towards themselves. But star has much more mass than planet that why it's looks like planet just orbiting only star.

[@LucasRichardStephens]

I feel there was somewhat of a lack of dimensions in this demonstration. Has the centripetal movement of the spiral in water been modelled mathematically now, I wonder? If so does explain how or why the water is condensed it this motion? Is there a connection or parallel between water in the river and stars in their galaxy?

[@MirFeriha]

Sir you the best🍃

[@talentlogic1512]

The man, the myth, the legend, Walter lewin. I’ve decided to watch all of your lectures, starting at the beginning, with 8.01 lecture 1. I’m on lecture 26 now. I love it, it’s fantastic. I have a degree in engineering, so I find physics to be very interesting.

[@huseyinsekerci6283]

Professor Lewin, have you ever thought sharing questions about special relativity or GR here?

[@lecturesbywalterlewin.they9259]

specvial relativity. YES I have done sevveral Bi-weekly problems with SR - GR is not possible at college level.

[@ekanshsinha3673]

Come to India sir please ❤❤❤❤.

[@ganesh3533]

Sir which one is good,Msc physics in nuclear physics or applied physics,can u please answer?!❤

[@lecturesbywalterlewin.they9259]

depends on your taste

[@ganesh3533]

@@lecturesbywalterlewin.they9259 I think nuclear is best for me

[@Aletheia.m.a.]

Sir if the revolving of planet is due to curved extra dimension according to Einstein, then why don't planet fall into star and collapse, neglecting the gravity? Thankyou❤

[@lecturesbywalterlewin.they9259]

use google

[@abulkhayer4898]

Sir I'm reading in class 9 and I have a question that....what force acts on photons so they move forward or why they move?.....what phenomenon caused it to move?....

[@lecturesbywalterlewin.they9259]

photons are massless they therefore must move with the speed of light. Photons have mometum, p, and energy, E and frequency f. E=pc=hf. use google

[@abulkhayer4898]

Thank you sir

[@micloue]

Sir, I have a question: What would be the consequences for our understanding of the universe if the speed of light were not an absolute limit, as postulated by Einstein's theory of special relativity?

[@lecturesbywalterlewin.they9259]

the consequence would probably be that the Universe could then not exist

[@micloue]

@@lecturesbywalterlewin.they9259 Merci pour ta réponse! Ma chaîne est en développement et j'apprécierais vraiment ton soutien en t'abonnant. Merci beaucoup!😁

[@unprovengravity]

Relativity: The Special and General Theory by Albert Einstein, page 61, paragraph 2. Zur Elektrodynamik bewegter Körper, translation- On the electrodynamics of moving bodies; by A. Einstein, Paragraph 2, sentence 1... Why did Einstein state this? Furthermore, if this were true at the time, and Einstein could not in fact detect earths motion, would the laws of physics today stay the same and still have correct mathmatical equations?

[@lecturesbywalterlewin.they9259]

take a course in GR - it's quite difficult though

[@omkar_thite]

Planets revolve due to space time but still follow newton's theory. Two different perspectives but both produce same results (equations)? I'm no expert but are both theories connected?

[@lecturesbywalterlewin.they9259]

Einstein's theory explained a famous observation that Newtonian gravity could not: a subtlety in the orbit of the planet Mercury. And his equations implied further slight deviations from Newtonian calculations.

[@asthargf]

The mavity of the situation 👀

[@meikejune4009]

This experiment looks easy to understand at the first look, but in real it is so crazy difficult.

[@lecturesbywalterlewin.they9259]

very true

[@Divyansh-ox4bf]

Sir soon I will share pdf of Ohanian physics with you ...... Thanks

[@amarlalsaw9243]

Suppose there is a spacecraft travelling with the speed of light ,now at that time its mass and also energy required to move it will become infinite.So according to Einstein's special theory of relativity [e=mc²],which tells us that mass and energy are both interchangeable,so if I change the mass of spacecraft travelling with the speed of light into energy that is then used to fuel it. -If I apply this concept then is it move with superluminal speed? Please tell me Love you Walter levin sir❤

[@lecturesbywalterlewin.they9259]

according to Einstein's Theory of SR, nothing that has rest mass can move with the speed of light. Light itself has no restmass (but it has momentum p, and Energy E, E=pc) photons therfore must move with the speed of light.

[@amarlalsaw7220]

Thanks for your answer but i have other doubt that sir you are telling that light also possess mass so how could it move with the speed of 3 lakh km/h.

[@lecturesbywalterlewin.they9259]

@@amarlalsaw7220 > *NOOOOOOOO I did not write that. Light has enery and momentum* *but no rest mass*

[@gabest4]

With this model no one mentions why two "depressions" would want to move towards each other. Isn't it because the fabric wants to stretch back to the smallest surface? I think there must be something similar to surface tension in space.

[@sujalpratapsingh5993]

Sir I have a doubt about light.Sir if light is massless then how does it have momentum

[@lecturesbywalterlewin.they9259]

light is massless but it has momemtum p which is E/c use google

[@user-vr5nx6kh1w]

Sir i had a question that pseudo forces don't even exist but we use them to solve all the numerical why so?

[@lecturesbywalterlewin.they9259]

they exist in the rotating frame of refence which is not a universal reference frame. use google.

[@MirFeriha]

I wonder how einstein gave this theory that too in earlier era ... i mean mind blowing

[@fehmidonmez7810]

Why does gravitation have one direction like downward in that experiment?

[@duckyoutube6318]

Its not downward. Its always pushing you towards the center of mass. Mass bends space. Space tells mass how to move.

[@duckyoutube6318]

On the surface of the earth it would appear that gravity pushes in the -y direction. Thus, this is why in kinematic equations gravity is taken as a negative number because it is pushing in the -y direction. Hope this helps!

[@russchadwell]

Oh! NOW I see... Use gravity to demonstrate gravity.

[@duckyoutube6318]

No you did not see. He used gravity to demonstrate the bending of space, or in this case, a sheet of cloth. Because you cant see the bending of empty space. Mass bends space. Space tells mass how to move. Watch again.

[@krishvekariya7598]

But like there isnt any particular direction where the mass will make a sink...like there are so many planes of rotation....and why would dat ball rotate around any other mass ....theres no gravity in space so planet must stay at its place even if theres a slope...its on earth that gravity makes everthing come down on slope... isnt it??

[@michaelbruning9361]

I've seen something like this before in a zoo. Instead of planets you could use pieces of money and in the middle there is a black hole that eats up all your money.

[@adamskywalker2327]

I believe this is not the best example to explain relativity. A better example whould be : "You and your friend are on the equator, 1000 miles apart. You both start due North. And meet at the north pole. If you didn't know the earth is a sphere, you would think that there was an attraction force between you two. But the reality is far from the truth!" The big reason because this example is not the best is, anyone can ask the question, the cloth-space that was curved because of the big mass is because this experiment is done on earth. If you did this experiment in the space the cloth-space will not curve and the big mass will just hover over the cloth.

[@peterlane7042]

I don't particularly like it either. It gives you the illusion that you understand GR. Why objects are attracted in GR is hand-waved away, letting gravity stand in for the mechanism behind gravity. It's a tautology. Gravity works because gravity causes things to attract each other.

[@jmcsquared18]

This is a disappointing demonstration decision. The trampoline analogy cheats quite badly, as it uses the gravitational weight of the ball to explainthe very phenomenon of the ball's gravity, which is completely circular. Feynman would not approve. Moreover, spatial curvature doesn't give rise to the gravitational field of the Earth in the weak-field limit. The time component of the curvature (the metric) contributes to the overwhelming majority of the acceleration due to gravity we experience. That requires more subtle analogies, of course, but this illustration does not suffice to convey how gravitation actually works in Einstein's theory of general relativity.

[@FrankPerau]

Is there a video that explains how this time component causes the acceleration? I always wondered how an apple gets its acceleration when you let it go.

[@user-MHR555]

Sir love from Bangladesh! Im in 11th class and pray for me i want to be a scientist 💫

[@mahinderpal9419]

So, I can safely say What sir Newton did was a sort of description of gravitation ,but Einstein gave an explanation of what gravitation is .

[@in-diaonic3391]

There is some inaccuracy in that understanding. Both, Sir Isaac Newton's and Einstein's models explain what gravity is, just with different approaches. Newton's model considered gravity a force while Einstein's model considered it a result of warping in the extra dimension of space-time. Einstein's GR doesn't explain WHY energy/mass makes space-time warp around them, this is an assumption (or a postulate) that the entire theory is based on. We also know that GR is not a perfect theory as it doesn't explain how gravity works at the quantum level.

[@moltenknightgaming4744]

love your lectures sir

[@lecturesbywalterlewin.they9259]

Glad to hear that

[@PrinceBlake]

The most important quality of gravity is that it traces out a regenerative wave structure called the Arrow of Time. At quantum scales, it is called the wave function. The most stunning find in recent years is that the structure of this gravity wave matches John's description of God's throne room in Revelation 4. How? Why? It appears it is possible to quantify this wave function in a logical manner by considering all the possibilities of paths available in the universe. For example, there is the path of least resistance that governs what pathway an object will take and there are the laws of linear and angular momentum to consider. My wife provided the missing piece of the puzzle. I had stalled out in my attempt to map out Time's arrow without using negative integers. The result is a conjunction between an ever-expanding path and an orbital path. When it comes down to it, there are only two types of pathways available to a vector. It can move linearly or it can be curved. One produces a line and the other a circle, all things being equal. Taking an average of all possible pathways allows us to peer into gravity's quantum mysteries. SanctionedIvan is a KZbin blogger and Putin critic who left Russia with his wife just days after the Concert Hall shooting and fire. His intention is to move to America but for now he is cooling his heels in Pattaya, Thailand. He doesn’t plan on spending a long time in Thailand so he recently purchased a car that many viewers advised him against - a used and modified power car. Even I joined the chorus of those cautioning against it. He struck out on his first attempts as the cars were in poor condition, but he hit pay dirt with a visit to Bangkok where he secured the car of his short-term dreams. kzbin.info/www/bejne/j16coqOafdipf68 15:35 is equal to 935 seconds. At this timestamp in his video “Buying My First Car in Thailand after Leaving Russia”, IIvan says "Bump". Consider that in Internet slang 'bump' means Bring Up My Post. From Wiki, "Bump' is used when a specific post has to be boosted enough for it to appear on top of the required page/feed. 'Bump' is commented on a post by many people and thus it appears on the top of the page, i.e. as the most important post of the page/feed." Also check out the odometer reading 4:53 (369250)and the license plate number 11:30 (5739) and see what numbers they have in common: 9, 3, and 5. These three numbers are found aligned at the core of model of the wave function that matches Biblical descriptions of God's engine room of Creation. Also, the number 935 is the sum of the object's expanding cross intervals from one generation to the next. 935 as a transliteration (a conversion from letter to number) is found in Yes, Yeshua, Jesuit, and Jesus: 935, 935HUA, 935UIT, and 935US.Why is this ‘935’, this Christlike number getting a 'bump' at the 935-second mark in this video (equal to 15:35)? It's not just happening in Ivan's videos, it's happening all over KZbin. Something big is happening in regards to the 935INE room of Time. God is trying to tell us something through Ivan's search for a powerful engine. Maybe God is reminding us not to forget that the most powerful engine of all is God's 935INE room as described in Revelation 4. Maybe he's pointing out that in God's throne room there are 24 Oddfellows (wise of both sexes) cheering on God's 935INE room of all creation. In other words, even God relies on the praise of the wise elders in comparison to the dictators who often appear on Earth to rely on their own prejudices and whim. the Bible says the 24 elders sit in even seats. evenly spread in a circle about the throne. By even, the Bible also means to show their wisdom and even-handedness and equity to one another. As we celebrate Ivan's turn towards America for freedom of speech, may we also celebrate this cue, this bump from God to remember the Big Engine, Our Creator and HIs Son, Our Lord 935US "Bump" Christ. Just maybe God is telling us that the Universe is a Living Object of Infinite Size. We have responsibilities to leave this blue marble to the next generation better than when we inherited it. My wife was awarded the premier award of the Institut Quantif’s Noble Prize in Physics for her discovery of Time’s Arrow, aka Matthewave 935. The award is not to be confused with Europe’s Alfred P. Nobel Prize. With the award to Mrs. Krchnak, the Institute Quantif hopes to bring humanity’s noble purpose into focus for the betterment of the next generation.

[@IsaacNewton.]

this is the longest youtube comment I have seen so far.....

[@Ayushsciphy]

I seen your video on Gyroscope. And I have a question what is the direction of produces torque when angular momentum changes.

[@lecturesbywalterlewin.they9259]

torque = dL/dt

[@Ayushsciphy]

@@lecturesbywalterlewin.they9259 means, toque is in the direction of changing angular momentum And so the torque of Mg on ring is balanced.

[@gaurav73539]

You are great sir❤

[@Harsha-bu7zq]

Don't you think he looks like Messi?

[@chinnuitube]

Isaac Newton? Gurutvakarshan was studied since ages in Bharathvarsh...

[@JEE_Beyond]

Sir i have a some confusion about space time theory for gravitation that einstein given, my confusion is sir if we are telling mass revolving around the big mass due to curvature in space and we are demonstrating the proof of the einstein theory with the help of plastic curves surface, but sir my thought is that mass is revolving around the center due to effect of components earth gravity and normal reaction from the surface (plastic,cloth)that acting on mass due to inclination of surface with horizontal, that make the mass to revolve due to centripetal acceleration. I think we should demonstrate this experiment where there is no net external force acting on the test body. Like in vacuum where no force is there even no gravitational pull of the earth. Sir please help me to clear my doubt.

[@lecturesbywalterlewin.they9259]

take a course in GR

[@divyanshkulshrestha7642]

​@@lecturesbywalterlewin.they9259adding on, the real space time is 3d. It is curved from every direction towards a mass present in it.

[@adamskywalker2327]

You and your friend are on the equator, 1000 miles apart. You both start due North. And meet at the north pole. If you didn't know the earth is a sphere, you would think that there was an attraction force between you two. But the reality is far from the truth! so the conclution is, the path of the smaller mass is not curved, it's still straight line. But the space in which its travelling in, just happend to be curved!

[@Blank_0P]

Don't write an essay bruh Hard to read For me & sir 🥸

[@Jamesbondhere]

What you're thinking is how the ball making a circular motion around the curve and you're right, the net force on the ball along the centripetal force makes the ball move in a circular motion, but the professor/lecturer is not explaining how the ball is moving around the object. This is just a demonstration relating to GR. The heavy object put at the center makes the cloth inclined which makes it look like the small object revolves around the heavy object (like planet - star system). Also the cloth here is like space-time curvature and a star is warped around it. That's the theory of General Relativity. Notice in the demonstration when we put 2 objects of nearly the same mass, both bend the space-time equally and they revolve around their center of mass (binary star system). This demonstration tells almost everything you need to know about GR. *Gravity in Newtonian mechanics is Space - time curvature in GR*

[@education7870]

I don't believe in that just to stay out of the science' religion and feel myself free.

[@sajjadurrehman1984]

Too simple, no explanation, why the earth does not fall on the sun?

[@user-xb5ys7hz4n]

Total pseudoscience!

[@ayushbais2504]

Care to explain?

[@adamskywalker2327]

I believe this is not the best example to explain relativity. A better example whould be : "You and your friend are on the equator, 1000 miles apart. You both start due North. And meet at the north pole. If you didn't know the earth is a sphere, you would think that there was an attraction force between you two. But the reality is far from the truth!" The big reason because this example is not the best is, anyone can ask the question, the cloth-space that was curved because of the big mass is because this experiment is done on earth. If you did this experiment in the space the cloth-space will not curve and the big mass will just hover over the cloth.