What I love about him is, his explanation seems so honest!. Unlike most professors I have seen, he doesn't use fancy words and act as if it's something everybody should know out. He calls out that words like Flat and curved are pretty abstract and that even he doesn't understand it. Such words feel very encouraging if you find it difficult to grasp these concepts.
Great answer, I am reading a book about how Einstein created general relativity, and this question indeed was one of his inspirations for his new theory. Thank you, this answer helped me to undertand this subject better.
The faint smile on his face through the entire video really conveys how much passion this professor has for physics. It seems to bring such a joy to him, that honestly, I'm jealous.
That is very well explained sir...one doubt if anyone can help. The change in time, or the time dilation that we are talking here in a strong gravitational field, isn't that itself came from the fact that speed of light is constant?
Actually I read your question once again.. you're right Under strong gravitational field time dilation occurs and in general we express it in terms of T(moving)=gamma×T(stationary).we can derive this by assuming two postulates of G.relativity. speed of an object is relative and c is the fastest speed for anything in the universe.Time depends ,it speeds up or slows down according to our speeds...but it also speed up of slows down according to the force which we experience due to gravity..... The first case is general relativity And the second one is special relativity. I don't know why but somehow c,t,g are related.
You can watch Fermi lab series on relativity ...it has helped me to understand it - somewhat...he is a source you can trust and don't forget Carl Sagan..his explanation are awesome.
Greetings sir. It is very kind of you to answer all our doubts and everything, so much grateful to you. I have a question sir if space and time is a same side of a coin if the space changes accordingly time also changes right sir! If that is so the accordingly changes doesn't be balanced to keep the speed of light a Constant one in non inertial frame sir? Thank you for your valuable time sir
Sir, Your explanation is really fantastic... But I am having a question - Light comes to Earth by travelling from sun and distance from the sun to the Earth cannot be said as local distance in space-time as it is a quite large distance but still we are defining velocity of light to be constant over such a large distance. So, what can be the explanation to this fact?
The ether is nothing, speed does not depend on distance and there is a phase when light changes it's speed after getting into earth's atmosphere it just a constant in a certain atmos
As answer to your question lies between dillema of earth is a inertial frame or not. It is inertial as it revolves around the sun with constant velo. But due to its rotation over axis produces centripetal acceleration it is non inertial so your answer lies between this
There is weak gravitational limit. Since earth is not as compact for general relativistic effects to be significant we can assume the spacetime around earth to be flat to a certain degree of approx. In this locally flat spacetime the speed of light is c. If u were on a blackhole this assumption would be invalid as the spacetime near blackhole is highly curved spacetime.
As the curvature increases in space time the time dilation occure and the distance become larger for light to travel Here at the same time distance increase and also time increase in the same amount so the value of speed become constant
Professor lets imagine that i had divided the spacetime into very small scales of dx and dt so that for each division there is no change in length scale and time scale now all i need to do is to add all the small length scale and time scale, calculate the errors and i have founded velocity in any direction and can also calculate acceleration can this work for both inertial and non inertial frames plz reply
Sir please make the concept clear of what is the meaning of constant k in F=kma. And also make me understand what is the meaning of constant in physic. Please tell me earlier because I am not able to study effectively. Please help me sir. 😔😔
Sir travelling with speed of light contracts space length and dilates the time.cant we take this fact to make speed of light constant both in inertial and noninertial frame?
Yeah but the point is that, those Lorentz transformations for curved spacetime are not linear, so you can't use them. It's like if you have a second degree polynomial, and you ask what is the rate of change from x=1 to x=10. That question doesn't mean anything because for a non-linear function, the rate of change is continuously different for every real value of x...
Sir if the velocity is not c is it more than c or less than c?If it is more than c won't Einstein contradict his own statement that "nothing travels faster than light". If somehow this is achievable then will we be able to accelerate things beyond the speed of light?
As proposed in the video that a frame can or can not have a gravitational field... hmmm but isn't it true that fields are always present in the 3+1 dimensions, they are part of spacetime itself? So a frame without a field needs to be outside the spacetime itself. Anyways any measurement of speed will be instantaneous and since EM waves don't require any medium to travel though, there isn't any relative relationship between the speed of EM waves from different frames, it will always be 'c' regardless of the frame's properties.
Speed of light is constant in relative motions not in the case when it passes a denser medium. It's speed slows down in denser medium, that's why refraction occurs.
I am very much interested to learn physics and do some research and advanced and deep study of physics and want to make our Bharat more advanced in science and technology.
why should we assume that time changes with curved space and not speed of the light? I understand that time at different space is different, but why should speed of light be constant and not time. Light traveling point a to point b on curved space will take same amount of time for light traveling from point a to point b on flat space. Here the explanation is time is slower on curved space, but my question is, why is it so, why cant we treat time as constant and say speed of light varies according to curvature of the space?
My answer may sound bizarre but don't blame a 10th grader. If you look at the time period formula, it's inversely proportional to acceleration due to gravity ( Too lazy to break my head ). Acceleration due to gravity depends on Gravity which curves space....so yeah. I guess you got my point. There is an equation to calculate *Time* *Dilation* . Google it if you wanna break your head.
Its just an assumption which is started by maxwell and continued to relativity by einstein that the light of speed is observer independent. And the results predicted by relativity matched with experiments. However,it is not proven.
At absolute zero temperature Pauli's Exclusion Principle fails. That is at this temperature atoms will not move relative to each other and all the atoms will clump/group together and will be in the same energy level as if they are a single atom.
No brother.... Although the direction of Earth is changing, but it's rotation tends to zero. Hence acceleration of Earth is considered to be zero. So, we are considered generally in inertial frame.
Light is made up of photons or quanta. Which are just the packets of energy They don't have mass. The momentum that we define for them is due to the energy they carry. So, the momentum of light is due to Energy and not mass itself.
Depends on if you are at rest or moving, * If at rest then your speed wrt light is same as speed of light *If your are moving then your speed wrt light is (V - C) ,where V is your speed and C is speed of light note it is a vector subtraction
@@shubhamjanagal7090 u haven't heard it carefully sir said it is not possible to define speed for a long interval of time.since it has no definite answer
Sir you say that in non inertial frame the velocity of light can not be defined So the gravitational force is everywhere It's because of any mass Then where can be the inertial frame possible
Even a non inertial frame has a particular velocity at any given instant. So momentarily the non inertial frame is identical to some inertial frame which matches this velocity. next instant the non inertial frame has a different velocity.... but there exist another inertial frame that again matches this new velocity and therefore identical to the non inertial one. 😂So instant by instant we can think of the nonertial frame as inertial frame only. And in each of these inertial frame the speed of light is c the universal constant. So collectively even the observer of a non inertial frame will also see the speed of light as c... no need to think of gravity or General relativity here.
Yeah... Actually due to gravitational force.. This huge fabric of cosmos, I.e.,spacetime bends... More the mass, more is the warping of space... And interestingly we can also pop the spacetime up by using negative mass
sir your explanation was fabulous, but I have one question that "If I travel at the speed of light and the light wave from the sun is also traveling with me, what is the speed of light with respect to me?"
Tarush Tandon as he said the shortest distance in gravitational field is curved so longer than even a straight line. Approximating or taking limit will also result in a different scale
Sir, maybe you should try talking to spiritual enlightened masters... They say space-time is really experiential in nature. If we pay attention to macroscopic changes on cosmic level, the changes seem to be at a less frequent pace with respect to time while if we observe changes at microscopic level, the frequency of changes is very high. Let's suppose we take a point to travel on the sine curve of changes happening at microscopic, macroscopic and cosmic level. The point will seem to move fast on the sine curve of microscopic sine curve line because of high frequency. If we observe the same on cosmic level the wave length of sine curve is huge, so the point on sine wave curve which may seem to be slow because of lower frequency will actually be high fast speed because of the big cosmic size at which we are dealing. If we observe the changes in our macroscopic observable world, the size is less but frequency higher than that of cosmic level and, the size of changes is more but less frequent than that of microscopic level. I am just trying to say, fundamentally everything is changing with same speed but it's basis of point of our experience that making anything seem to be slow or fast.
ajj pura desh ek bihari se physics pardh raha hai aur log dekh rahe hain ki bihari ko jaisa dikhaya jata hai woh waise nahi balki knowledge with decent hote hain
@@thebhaskarrajput abe gadhe pahale padh le aur smjh bhi le tb bola kr aur ye jan le tu ek darshanik se bat kr raha h jara sonch samjhkr bola kr. Pahle mera comment ko padh aur smjh ki maine kya bola h tu sonch raha h ki mai angreji bolane ki bat kr raha hun per tujhe smjh nahin aaya ki maine hindi ko prtoshahit kiya h.
KYA BHAI AAP ENTRANCE HINDI MEI DOGE KYA PHYSICS ENGLISH MEI SAMZE TO BEHTAR HAI HINDI MEI KUCH NAHI CLEAR HOGA KYA CHAL RAHA HAI AUR KUCH KAHNE KI JARURAT NAHI HAI AAP SAMAZ GYE HONGE
@@beeta108_kartikkumarathani9 tumhare jaise sonch ke karan hin ye bharat puri trh bs handicap bnkr rah gya h ek bat aaj jan lo ki yahi isthiti rahi to tumlog kabhi vigyan ki duniya me kuchh naya nahin kr skte bs dusron ki do huyi chijono ko ratne ka hin pryas krte raho.
2:44
He says "I don't understand much"..
Shows his intense humbleness....
What a great personality he is..!!
What I love about him is, his explanation seems so honest!. Unlike most professors I have seen, he doesn't use fancy words and act as if it's something everybody should know out. He calls out that words like Flat and curved are pretty abstract and that even he doesn't understand it. Such words feel very encouraging if you find it difficult to grasp these concepts.
i totally agree with you and apreciate the fact that you understand him so well and the way you have described him is just exceptional
Great answer, I am reading a book about how Einstein created general relativity, and this question indeed was one of his inspirations for his new theory. Thank you, this answer helped me to undertand this subject better.
YOUR BOOK MAKES MY PHYSICS BASIC CONCEPTS CRYSTAL CLEAR & STRONG
What's the name of book?
Concepts of physics, of course
your contribution to society is par excellence , keep it up sir
Kya baat hai sir...nice... this little bit explanation about GTR is awesome
My favourite prof. In world
Sir you are genius.Your physics is still my favourite book.
undoubtedly,Sir is genius but the concept of physics is super overrated book
It should not be your favorite book
The faint smile on his face through the entire video really conveys how much passion this professor has for physics. It seems to bring such a joy to him, that honestly, I'm jealous.
Shandaar Sir.
I am in science college but I prefer ur lecture than my professor
You are best sir apka lectures se very very help ho raha h thanku so much
That is very well explained sir...one doubt if anyone can help. The change in time, or the time dilation that we are talking here in a strong gravitational field, isn't that itself came from the fact that speed of light is constant?
Hope it helps
@@AmanDeep-yc4iz Thanks bro...I'll try to understand it
Actually I read your question once again.. you're right
Under strong gravitational field time dilation occurs and in general we express it in terms of
T(moving)=gamma×T(stationary).we can derive this by assuming two postulates of G.relativity. speed of an object is relative and c is the fastest speed for anything in the universe.Time depends ,it speeds up or slows down according to our speeds...but it also speed up of slows down according to the force which we experience due to gravity.....
The first case is general relativity
And the second one is special relativity. I don't know why but somehow c,t,g are related.
You can watch Fermi lab series on relativity ...it has helped me to understand it - somewhat...he is a source you can trust and don't forget Carl Sagan..his explanation are awesome.
@@AmanDeep-yc4iz yeah bro..thanks for explaining😎
Mazaa aagaya sir !
Sir you are legend of iit
YES OBVIOSLY BRO
Greetings sir. It is very kind of you to answer all our doubts and everything, so much grateful to you. I have a question sir if space and time is a same side of a coin if the space changes accordingly time also changes right sir! If that is so the accordingly changes doesn't be balanced to keep the speed of light a Constant one in non inertial frame sir?
Thank you for your valuable time sir
Sir, Your explanation is really fantastic...
But I am having a question - Light comes to Earth by travelling from sun and distance from the sun to the Earth cannot be said as local distance in space-time as it is a quite large distance but still we are defining velocity of light to be constant over such a large distance. So, what can be the explanation to this fact?
The ether is nothing, speed does not depend on distance and there is a phase when light changes it's speed after getting into earth's atmosphere it just a constant in a certain atmos
As answer to your question lies between dillema of earth is a inertial frame or not. It is inertial as it revolves around the sun with constant velo. But due to its rotation over axis produces centripetal acceleration it is non inertial so your answer lies between this
Speed of light is constant in vaccum.
There is weak gravitational limit. Since earth is not as compact for general relativistic effects to be significant we can assume the spacetime around earth to be flat to a certain degree of approx. In this locally flat spacetime the speed of light is c. If u were on a blackhole this assumption would be invalid as the spacetime near blackhole is highly curved spacetime.
As the curvature increases in space time the time dilation occure and the distance become larger for light to travel
Here at the same time distance increase and also time increase in the same amount so the value of speed become constant
Sir how can we say that light speed is constant
@Nikhil Gaonkar thnx
Awesome sir
Professor lets imagine that i had divided the spacetime into very small scales of dx and dt so that for each division there is no change in length scale and time scale now all i need to do is to add all the small length scale and time scale, calculate the errors and i have founded velocity in any direction and can also calculate acceleration can this work for both
inertial and non inertial frames plz reply
No we don't know how space and time is changing we need a relation or function to integrate
@@vishesh5492 Couldn't agree more👏
But quantum mechanics does not agree , because firstly you difine ,how the space made form
Kya wastab m time hota h ya ensano ke dwara ye banaya gaya h agar ensaan time ko mapne ke liye koi ekai banata hi nahi to time kase hota?
Bruh..Go and learn Special Theory of Relativity!
Sir please make the concept clear of what is the meaning of constant k in F=kma. And also make me understand what is the meaning of constant in physic. Please tell me earlier because I am not able to study effectively. Please help me sir. 😔😔
Here K is unit force whose value is 1 constant in physics is its value never changes
Is light is also affected by gravity?
Yes at black holes
Yes gravity affects light.
Yes bro light of stars is curved
due to space time curvature
Yup because it has mass in motion
Sir then how we will explain time deletion
Light speed should be const in non inertial frame
Mind blowing
Why is spacetime curved by mass but not charge?
It is curved by mass of the charge
@@alapandas6398 Because electric field and magnetic field needs a net charge on the body
Sir travelling with speed of light contracts space length and dilates the time.cant we take this fact to make speed of light constant both in inertial and noninertial frame?
Yeah but the point is that, those Lorentz transformations for curved spacetime are not linear, so you can't use them. It's like if you have a second degree polynomial, and you ask what is the rate of change from x=1 to x=10. That question doesn't mean anything because for a non-linear function, the rate of change is continuously different for every real value of x...
Sir sunne me to bohot achha laga par samajh me jyada kuch nahi aaya
Sir if the velocity is not c is it more than c or less than c?If it is more than c won't Einstein contradict his own statement that "nothing travels faster than light". If somehow this is achievable then will we be able to accelerate things beyond the speed of light?
Every object have masses the real enisten equation is E^2=(mc^2)^2+(pc) ^2 if you put m= 0 then you achive light of speed
I know the universe expanding with c^2 but we don't know about dark matter and dark energy
But light would still travel shortest path in the curved space..
As proposed in the video that a frame can or can not have a gravitational field... hmmm but isn't it true that fields are always present in the 3+1 dimensions, they are part of spacetime itself? So a frame without a field needs to be outside the spacetime itself. Anyways any measurement of speed will be instantaneous and since EM waves don't require any medium to travel though, there isn't any relative relationship between the speed of EM waves from different frames, it will always be 'c' regardless of the frame's properties.
Yes I agree
This question began relativity😎
I think you didn't heard about Gallielian Relativity
Sir..If speed of light is constant so how refraction occurs ???
Speed of light is constant in relative motions not in the case when it passes a denser medium. It's speed slows down in denser medium, that's why refraction occurs.
fantastic Sir👍
Love u sirji
All time great...
Can it be greater than c?
I am very much interested to learn physics and do some research and advanced and deep study of physics and want to make our Bharat more advanced in science and technology.
Agar ham har gati ko kisi ke saapeksh mante h to light ki speed ko kisi ke saapeksh kyu nahi ?
why should we assume that time changes with curved space and not speed of the light? I understand that time at different space is different, but why should speed of light be constant and not time.
Light traveling point a to point b on curved space will take same amount of time for light traveling from point a to point b on flat space. Here the explanation is time is slower on curved space, but my question is, why is it so, why cant we treat time as constant and say speed of light varies according to curvature of the space?
My answer may sound bizarre but don't blame a 10th grader. If you look at the time period formula, it's inversely proportional to acceleration due to gravity ( Too lazy to break my head ). Acceleration due to gravity depends on Gravity which curves space....so yeah. I guess you got my point.
There is an equation to calculate *Time* *Dilation* . Google it if you wanna break your head.
Its just an assumption which is started by maxwell and continued to relativity by einstein that the light of speed is observer independent.
And the results predicted by relativity matched with experiments.
However,it is not proven.
sir mery question ka jawab ni mila
What will be the object looks if it is kept at 0 kelvin
Freezed
At absolute zero temperature Pauli's Exclusion Principle fails.
That is at this temperature atoms will not move relative to each other and all the atoms will clump/group together and will be in the same energy level as if they are a single atom.
Time kaha se aaya sir😔 koi bata do plss
You are best sir
❤❤❤
Sir, kindly clear my concept on the limit of Galaxy...
The only concept this is Limitless
Earth has gravity
That means we are also in non-inertial frame?
No brother.... Although the direction of Earth is changing, but it's rotation tends to zero. Hence acceleration of Earth is considered to be zero. So, we are considered generally in inertial frame.
@@sonugagankarn
Thanks
Oh acceleration is constant
😊
Sir they say light has momentum but how can something massless can have momentum?
Light is made up of photons or quanta. Which are just the packets of energy They don't have mass. The momentum that we define for them is due to the energy they carry. So, the momentum of light is due to Energy and not mass itself.
@@rudranshsharma6255 what about p=mv
@@TheRetirementRoadmap Quantum physics bro.. E=mc^2
E = (mc)*c
E = P* C
(P = momentum and C = speed of light )
Sir can u say something on what is our speed with respect to light
Depends on if you are at rest or moving,
* If at rest then your speed wrt light is same as speed of light
*If your are moving then your speed wrt light is (V - C) ,where V is your speed and C is speed of light
note it is a vector subtraction
So speed of light is not constant as well
@@abhaypratapsingh1579 speed of light wrt to a observer at rest or moving with a constant velocity is constant
But when I said I am moving with a constant velocity
Assume I am having acceleration then even light will be constant
1 course we want on general relativity
You didn't answered how or why light speed seems constant even if our velocity changes
Sir answer to Mila nhi😒😒
Plz reply anyone
@@shubhamjanagal7090 u haven't heard it carefully sir said it is not possible to define speed for a long interval of time.since it has no definite answer
Thank u sir..
Sir how I can contact with you ....plz
Sir you say that in non inertial frame the velocity of light can not be defined
So the gravitational force is everywhere
It's because of any mass
Then where can be the inertial frame possible
0g can be obtained even on earth by using various setups. That can be considered as an inertial frame of reference
earth is also a non inertial frame
Sir, how can I show this in mathematical form??
For this you need to know
Tensor calculus and differential geometry
Even a non inertial frame has a particular velocity at any given instant. So momentarily the non inertial frame is identical to some inertial frame which matches this velocity. next instant the non inertial frame has a different velocity.... but there exist another inertial frame that again matches this new velocity and therefore identical to the non inertial one. 😂So instant by instant we can think of the nonertial frame as inertial frame only. And in each of these inertial frame the speed of light is c the universal constant. So collectively even the observer of a non inertial frame will also see the speed of light as c... no need to think of gravity or General relativity here.
Yeah... Actually due to gravitational force.. This huge fabric of cosmos, I.e.,spacetime bends... More the mass, more is the warping of space... And interestingly we can also pop the spacetime up by using negative mass
Sir please upload the topic de sittar relativity
Unbelievable...
Thanks sir
I knew that space-time bends but I want to know in that manner does it bend
Excited for 15 August
Iam feeling that u r books are so difficult. Include more basics from ground level please.
sir your explanation was fabulous, but I have one question that "If I travel at the speed of light and the light wave from the sun is also traveling with me, what is the speed of light with respect to me?"
c-c=c ...photon experiences no time
I'm in 10th now, and I'm sure it's not for my brain 🧠😬
Your comment is *IRONIC*
@@pfft3158 how ??
But can it ever be greater than c in a non inertial frame?
Tarush Tandon as he said the shortest distance in gravitational field is curved so longer than even a straight line. Approximating or taking limit will also result in a different scale
Thanks shehraj singh
Legend
Lovely.
Sir, why gravitational potential energy is negative
Sir, maybe you should try talking to spiritual enlightened masters...
They say space-time is really experiential in nature.
If we pay attention to macroscopic changes on cosmic level, the changes seem to be at a less frequent pace with respect to time while if we observe changes at microscopic level, the frequency of changes is very high.
Let's suppose we take a point to travel on the sine curve of changes happening at microscopic, macroscopic and cosmic level.
The point will seem to move fast on the sine curve of microscopic sine curve line because of high frequency.
If we observe the same on cosmic level the wave length of sine curve is huge, so the point on sine wave curve which may seem to be slow because of lower frequency will actually be high fast speed because of the big cosmic size at which we are dealing.
If we observe the changes in our macroscopic observable world, the size is less but frequency higher than that of cosmic level and, the size of changes is more but less frequent than that of microscopic level.
I am just trying to say, fundamentally everything is changing with same speed but it's basis of point of our experience that making anything seem to be slow or fast.
Space like, time like,light like interval read about these three terms guy's
Anyone from IIT?
sir bihari ki image badal kar rakh di apne india ke samne
How?
ajj pura desh ek bihari se physics pardh raha hai aur log dekh rahe hain ki bihari ko jaisa dikhaya jata hai woh waise nahi balki knowledge with decent hote hain
sir please explain in hindi
Bhai.. IIT mein class chal rha hai..koi majak nhi hai..sir ka without iit class Dekho
BRO SCIENCE HUM ENGLISH MEI HI PADHE TO ACHHA HAI
@@beeta108_kartikkumarathani9 tumhari baton se hin mai bata skta hun ki tumhe vigyan ki koi smjh nahin isiliye aisi bat bol rahe ho .
@@नेत्रावेदी kyon be tujhe jada angreji ati hai kya?
@@thebhaskarrajput abe gadhe pahale padh le aur smjh bhi le tb bola kr aur ye jan le tu ek darshanik se bat kr raha h jara sonch samjhkr bola kr.
Pahle mera comment ko padh aur smjh ki maine kya bola h tu sonch raha h ki mai angreji bolane ki bat kr raha hun per tujhe smjh nahin aaya ki maine hindi ko prtoshahit kiya h.
Great. I m not an expert of general theory of relativity.
Sir explain in Hindi ... Pls sir
Sir Hindi Me Samjhaiye
KYA BHAI AAP ENTRANCE HINDI MEI DOGE KYA
PHYSICS ENGLISH MEI SAMZE TO BEHTAR HAI
HINDI MEI KUCH NAHI CLEAR HOGA KYA CHAL RAHA HAI
AUR KUCH KAHNE KI JARURAT NAHI HAI AAP SAMAZ GYE HONGE
@@beeta108_kartikkumarathani9 tumhare jaise sonch ke karan hin ye bharat puri trh bs handicap bnkr rah gya h ek bat aaj jan lo ki yahi isthiti rahi to tumlog kabhi vigyan ki duniya me kuchh naya nahin kr skte bs dusron ki do huyi chijono ko ratne ka hin pryas krte raho.
Anybody who understood general theory of relativity?
fantastic Sir👍