Thanks :)

They are already big but in french 😁

👍👌

Why wouldn't it be available without the lockdown?

These videos have already been published over a year ago on the main ScienceClic channel over a year ago - in french dub though. So the majority of the work has already been done I believe.

It's was available in french berofe the english chanel started. It was before lockdown

@@lounesz.5156 I just noticed there have been many General Relativity educational videos created in 2020. Veritasium, PBS Spacetime, and Minute Physics have all created new videos on General Relativity. Even at Science Asylum there was a new video on tensors, but it may have been produced before the lockdowns.

based covid

It's impossible to denote Tensors any other way. If you are a physics student, just know that there are much harder things in the world.

@@aniksamiurrahman6365 I think they were referring to "mu" and "nu". They could have easily named them something else.

@@APaleDot No matter what system u adapt, I believe they'll end up just as complex.

@@aniksamiurrahman6365 It has nothing to do with the complexity of the system. It's specifically about how the names of variables sound when spoken aloud.

@@APaleDot They're greek letters, and they are not pronounced like in the video. µ is pronounced "mi", and ν is pronounced "ni". Not really that important to distinguish them either, just need to know that they are indices. Anybody can mix them up or switch them out. Not like it's suddenly much harder just because the letters are similar. They don't matter that much.

Thanks ! I think so too :)

Get rid of the “the”. Saying “the humanity” would be referring to being humane and not all people

@@biblebot3947 isnt it the opposite?

Yeah it's the kind of thing you only do once. Thankfully wolfram alpha lists all of these values related to several coordinate systems

It is! But it is worth and a good practice to calculate all those objects (metric tensor, Christoffel symbols, Riemann curvature tensor, Ricci tensor and Ricci scalar) by hand. It takes a while but this will teach your brain :)

You really need to understand Vector Calculus to get a conceptual grasp of Tensors because Tensors are extensions of vectors.

One way to think about it is you are holding a stick pointed straight ahead from you ( lets say pointing straight ahead away from your nose ) and you keep walking. If you walk straight , then you keep holding it straight ahead. Now if you turn 90 degrees to the left, then instead of turning the stick along with you, you try to keep it as it was. So, once you have completed the turn , now the stick should be pointing away out of your right ear. Whenever you move , you just keep following this rule. That is parallel transport

@@silverrahul Nevertheless, as Collaz said, the upper and lower arrows move to the right in a different manner. More specifically, the upper arrow moves "parallel" to itself, but the lower didn't. That makes the comparison not very convincing since it's normal the resulting orientation is different. That said, perhaps the results would *also* have been differents if the arrows had moved in the same manner.

@@joluju2375 " _More specifically, the upper arrow moves "parallel" to itself, but the lower didn't. That makes the comparison not very convincing since it's normal the resulting orientation is different._ " That is the whole point. That the resulting orientation is different because of the different topology of the surface.

@@silverrahul I stopped the video at this point since I’m siding with Jolulu on this one, perhaps there is an explanation further in in the video, but for now I can’t help myself from getting into the discussion. The lower arrow keeps the head pointed towards the “north pole” while the higher arrow keeps it angle intact relative to our perspective which makes it deviate from pointing towards the North Pole and instead pointing eastwards. I believe what is lacking is proper usage or visualization of geodesics vs curved lines. In the video, both arrows move upwards in a straight line (geodesic) while the sideways motion is not (can’t remember if the lower lateral movement is on the equator) or at least not the upper lateral movement. Point is, if you have two vectors on spherical coordinate system, moving the vectors in a straight lines only (geodesics) but in different orders like in the video should render the effect the video is supposed to demonstrate. Instead he is actually n o t moving the vectors in straight lines with the same angle in reversed orders, by not following a geodesic the lateral movement is actually curved. Meaning the lower vector is moving laterally in a straight line if on the equator or with a flatter curve compared to upper vector’s lateral movement if not on the equator.

@@johanpersson8156 I have no recollection what the discussion was. This was from 6 months ago.

std?

@@llamatown8160 sus

I'm in 7th grade and I can understand and work on general relativity problems.... I have studied quantum mechanics too.

@@brett_webber233 nice to hear

@@brett_webber233 can you do calculus as well?

Whoa! Calculus anyone?

@@aniksamiurrahman6365 Vector calculus

Thank you :)

Thank you very much, it's great that in highschool you're already interested in such topics !

Thank you ! Glad you like it :)

Seshnag R follow prof Leonard susskind if you want to learn the mathematics behind these nice explanations

Raytracing in realtime is impossible at the moment, but it can be done with some approximations in certain specific situations. Check out my personal channel "Alessandro Roussel", I am developing an algorithm to do some realtime relativistic "raytracing" around black holes (it's not really raytracing as my algorithm gets rid of integrals, but the maths that are involved are doing the raytracing in a way)

Thanks !

Same. But thinking of R tensor as a tool and not something physics helps a bit

@@abhijithcpreej go for weyl tensor

That's a necessary condition before understanding GR

Take a Ricci aspirin.

Thanks !

if there is gravitation then it's not flat Minkowski space any more

The vector transpositions are along the basis vectors of the space. (i.e. in the direction of the derivatives of the basis vectors) There is no need to the basis vectors to be 90 degrees (ortogonal). It all depends on what coordinate system is chose to span the space.

The 16 components is a consequence of mapping 4D spacetime on a matrix. The rows and columns each encode one temporal and three spatial components, and so 4*4=16 total matrix components.

There are 16 components in 2D, because a component of the Riemann tensor corresponds to : - a choice of basis vector (2 possibilities) - a choice of coordinate to transport along (2 possibilities) - a choice for another coordinate to transport along (2 possibilities) - a choice of component to express the vector R (2 possibilities) So this yields 2*2*2*2=16 possibilities. If we have 4 coordinates (in a 4D spacetime in particular) then this would be 4*4*4*4=256. So the Riemann tensor always have N⁴ components, where N is the dimension of the surface on which we calculate it. The vectors are transported along the coordinates that we choose. The coordinates are completely arbitrary, it's just a grid that we draw on the surface. So we can choose the axis to be perpendicular or not, it's arbitrary. That's the great power of this formalism : everything works regardless of the grid we use.