What is General Relativity Lesson 1: Prerequisites, Books, Units, and Syllabus

What is General Relativity Lesson 1: Prerequisites, Books, Units, and Syllabus.

This is the introduction/invitation/welcome to a course in General Relativity.

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[philipchristiansen]

I feel like they are barely any GR series on youtube in this style. I'm very much looking forward to this!

[jakeaus]

I am so hyped for this series. My objective in studying GR has always been to get beyond the "ball on a rubber sheet" analogy to the heart of how it really works.
You make a really interesting observation at 37:00 about how Einstein arrived at his result, more by working backward from intuition than from the ground up. I read a really great biography of his and this seemed to be his approach to most things he thought about. Something like "I reckon it should work this way, and I know it sounds far out but it would totally work, I've got this funny feeling about it...", and sure maybe lots of people have had strange intuitions, just happens that Einstein's was on the right wavelength.
I'm really enjoying your Tensor series at the moment. Great to see all the stuff that is actually behind the scenes when you're presented with some tensor straight up.
If I could make one small suggestion, whenever you say something like "*This* object over here is related to *that* one there", it is helpful when you also point to them with the red dot so its clear which thing you are referring to.
Cheers!

[dunningrb]

This is a really fantastic channel. Thank you so much for putting all this together. I plan on going through as many videos as I can before I die!

[steveboigon]

i love all your lectures on tensors and manifolds and look forward to this series..however!!..who are you?? you obviously are extremely knowledgeable and are an excellent teacher..xylyxulyx is not divulging much..about yourself and i am interested!!

[Hannah-nfgf]

I just want to say thank you for this series, I'm grateful to you for taking the time to expand on concepts that seem obvious or implied in GR textbooks or lectures but are often missing in a student's knowledge base. Truly a public service you're doing here :) It definitely improved my confidence tenfold as I went through GR and I know it will do the same for others.

[ManishKumar-nrde]

Great work, looking forward for upcoming lectures

[IronCharioteer]

This is a wonderful series of vids. As he says in lesson 3, though, this series isn't really for people who haven't already been introduced to GR. Its a "second pass" series, as he calls it. I'm in a GR class which works from Weinberg's Gravitation and Cosmology and this series is awesome at reinforcing and illuminating the concepts introduced in that book. The book doesn't really use pictures so its hard to visualize what the math means and implies, but that's where this series comes in and shines.
Great work Xyl!

[larsbjrn]

Finally, I find the gold mine :p I will start your lectures today and they seem perfect to me. I am reading the Schutz A First Course in General Relativity(Second Edition). Its also a great book (in my opinion) but details are missing(which is normal since its an inroductory book). I am sure that your videos will help me to learn GR.

[TheJara]

Thank you so much for this labour of love...immensely helpful..

[signorellil]

Fantastic! Please keep this series coming!

[rktiwa]

In india we celebrate teacher's day today. I thank you my dear teacher for pulling me out of the murky depths of ignorance.

[earthperson]

11-7-17
So glad to get going on GR!
Thanks!

[shivamkumarmishra]

Your voice sounds very similar to Sean Carroll. Nice video.

[zarofara]

Hey man, I just want to tell you I really appreciate the vids you've made.

[haneen]

Awesome video, thanks for sharing your knowledge!

[andrewsheehy]

This is good. On many levels. Love it!

[Achrononmaster]

@44:00 seems a bit Frankenstein? Fwiw I've always thought the more natural and intuitive way to approach the GR field equations was from the variation of an Action principle. I've never seen a nice course going that route first-up, but it is so satisfying someone ought to go that route for beginners. Particles do *_not_* follow geodesics is the problem, not in quantum mechanics. So the metric-first approach has a bias against a possible natural "quantum gravity" approach. It's best to think of GR as already a quantum theory by assuming there are closed timelike curves at about the Planck scale. A Lagrangian approach is great for this sort of physics, since you naturally get a path integral picture.
Would be thus good to teach this right, GR from Action principle? In the quantum theory you have to use a Lorentzian path integral which is notoriously tricky, but Feldbrugge, Job, Boyle and Turok and others use Picard—Lefschetz to work with the Lorentzian path integral quite effectively. I'd put this near top of my wish list for EduPhys-tube.

[LibertyAzad]

Love your videos, and recently discovered you finally have a book.
Just curious, is the "Why does it move?" book printable? --(that would be easier on my eyes)

[frankbennett]

1) Isn't the curvature tensor, R, a function of space-time having two lower indices?

2) I don't understand natural units. If we measure the mass of a star in meters, what does this mean? A million meters say, means what?

3) If the field equations without the CC imply *either* an expanding or contracting universe (which is what I recall), why did Einstein introduced the CC as a repulsive force to presumably counteract contraction due to gravity (to get a steady state solution), but later lamented he could have predicted an expanding universe? Something about this story is incongruous if my facts are correct.

Thanks for your time.

[Tracks]

When is your next video? :D Keep it up!