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Possible to self-teach General Relativity?

This may be absurd (feel free to tell me so) but i have always wanted to study the Physics of space-time and eventually General Relativity. Looking around, this seems to be a 3rd/4th year option... but i really don't want to wait that long, and i have an entire summer of boredom to fill. Is it at all possible to self teach the materials required to get even a basic understanding of space-time? Obviously i have an understaning of what GR is, i mean from a mathematical stand point?

I've just finished my A-Levels so my vector knowledge streches only as far as FP3 (dot/cross products, intersection of planes etc) and (i think) i'm fairly competant at Special Relativity, though this may only be because certain mathematics has been ommitted from books i have read. I am confident with Lorentz transformations, etc.

Every time i look up anything on the topic i get lost at mathematical techniques i don't know (vector calculus, tensors, geodesics, partial differentiation, etc) and when i look up one of these it requires knowledge of another. Could someone tell me where to start? Which order to learn these techniques? Any books or websites recommended?

I guess i'm just crazy trying to learn this, it's done in fourth year for a reason. I just started reading the Feynman's Lectures chapter on space-time and i wondered whether with a whole summer free, it would be possible?

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I have been interested in GR for 6+ years now and when I got into my 2nd year of University I'd had enough of waiting for the 4th year course so I decided to teach it to myself. I bought Relativity Demystified and sat down with it and worked through it. Its got all the mathematics in it and all the physics. The biggest hurdle is the mathematics and notation; the notation adopted by GR (and all similar physics like QFT) could be described as a "generalised vector".

If I have a vector, I could write it in cartesian coordinates as:

r=Ai+Bj+Ck \mathbf{r} = A \mathbf{i} + B \mathbf{j} + C \mathbf{k}

or polar coordinates as:

r=Dr^+Eθ^+z^ \mathbf{r} = D \mathbf{\hat{r}} + E \mathbf{\hat{\theta}} + \mathbf{\hat{z}}


But here we are specifying the coordinate system. So I can choose a notation that is coordinate independent, a sort of standardised notation:

r=a1e1+a2e2+a3e3=i=13aiei \displaystyle \mathbf{r} = a_1 \mathbf{e_1} + a_2 \mathbf{e_2} + a_3 \mathbf{e_3} = \sum_{i=1}^{3} a_i \mathbf{e_i}

I then later decide what my coordinates are and I can make the e's become the i's,j's and k's if it is cartesian coordinates we are dealing with.

Once you conquer the idea of this standardised notation, you can then move on to trying to understand tensors and how they relate different vectors to each other. I'd say it was do-able to a certain point, it may be the mathematics that holds you back. The ideas of GR are accessible without lots of maths but to understand them properly I think you need to understand the mathematics properly first. Most people met this type of maths in their 3rd year at university, probably in a course on Electrodynamics or Elasticity.
0 div curl F
I have been interested in GR for 6+ years now and when I got into my 2nd year of University I'd had enough of waiting for the 4th year course so I decided to teach it to myself. I bought Relativity Demystified and sat down with it and worked through it. Its got all the mathematics in it and all the physics. The biggest hurdle is the mathematics and notation; the notation adopted by GR (and all similar physics like QFT) could be described as a "generalised vector".

If I have a vector, I could write it in cartesian coordinates as:

r=Ai+Bj+Ck \mathbf{r} = A \mathbf{i} + B \mathbf{j} + C \mathbf{k}

or polar coordinates as:

r=Dr^+Eθ^+z^ \mathbb{r} = D \mathbb{\hat{r}} + E \mathbb{\hat{\theta}} + \mathbb{\hat{z}}


But here we are specifying the coordinate system. So I can choose a notation that is coordinate independent, a sort of standardised notation:

r=a1e1+a2e2+a3e3=i=13aiei \displaystyle \mathbb{r} = a_1 \mathbb{e_1} + a_2 \mathbb{e_2} + a_3 \mathbb{e_3} = \sum_{i=1}^{3} a_i \mathbb{e_i}

I then later decide what my coordinates are and I can make the e's become the i's,j's and k's if it is cartesian coordinates we are dealing with.

\mathbf{} (boldface), not \mathbb{} (blackboard bold), which seems to give some odd Hebrew characters when you try to make small letters bold. :p:
0 div curl F
I have been interested in GR for 6+ years now and when I got into my 2nd year of University I'd had enough of waiting for the 4th year course so I decided to teach it to myself. I bought Relativity Demystified and sat down with it and worked through it. Its got all the mathematics in it and all the physics. The biggest hurdle is the mathematics and notation; the notation adopted by GR (and all similar physics like QFT) could be described as a "generalised vector".

If I have a vector, I could write it in cartesian coordinates as:

r=Ai+Bj+Ck \mathbf{r} = A \mathbf{i} + B \mathbf{j} + C \mathbf{k}

or polar coordinates as:

r=Dr^+Eθ^+z^ \mathbf{r} = D \mathbf{\hat{r}} + E \mathbf{\hat{\theta}} + \mathbf{\hat{z}}


But here we are specifying the coordinate system. So I can choose a notation that is coordinate independent, a sort of standardised notation:

r=a1e1+a2e2+a3e3=i=13aiei \displaystyle \mathbf{r} = a_1 \mathbf{e_1} + a_2 \mathbf{e_2} + a_3 \mathbf{e_3} = \sum_{i=1}^{3} a_i \mathbf{e_i}

I then later decide what my coordinates are and I can make the e's become the i's,j's and k's if it is cartesian coordinates we are dealing with.


Ah, okay. Thanks!

Yeh, the notation gets me confused whenever i've started these books that are too advanced.

Thanks for the recommendation of the book - it sounds excellent. Who is the author "David McMahon and Paul M. Alsing" or "R Wolfson"?

From what i could see the first bits of mathematics i need to learn are 'multivariable calculus' and 'linear algebra'. Would this book even cover these basic techniques in enough detail for me to learn them?

Thanks for responding.
generalebriety
\mathbf{} (boldface), not \mathbb{} (blackboard bold), which seems to give some odd Hebrew characters when you try to make small letters bold. :p:



Yep lol, I couldn't remember the correct command but I'm sure bb does something sensible in my tex program. All sorted now.
Reply 5
I don't think that an A Level student can understand general relativity in any meaningful sense, and certainly not in a summer. If you really wanted to be able to do all the maths, you'd have to learn:

Multivariable calculus
Linear algebra
Ordinary and partial differential equations
Differential geometry

Plus all of the prerequisites... and the prerequisites for the prerequisites.

General relativity is taught as a third year undergraduate course in Cambridge, and even then I don't think you do anything other than scrape the surface until the fourth year course.

You'd do much better reading popular science books (Brief History of Time, Elegant Universe, QED) in my opinion.
schrodinger's cat
Ah, okay. Thanks!

Yeh, the notation gets me confused whenever i've started these books that are too advanced.

Thanks for the recommendation of the book - it sounds excellent. Who is the author "David McMahon and Paul M. Alsing" or "R Wolfson"?

From what i could see the first bits of mathematics i need to learn are 'multivariable calculus' and 'linear algebra'. Would this book even cover these basic techniques in enough detail for me to learn them?

Thanks for responding.



Yes its the McMahon one. Multivariable calculus is an extension to single variable calculs. If your fluent in normal calculus, like:

y=x2dydx=2x \displaystyle y = x^2 \to \frac{d y}{dx} = 2x

Then multivariable calculus is the natural extension: In the above derivative the quantity y is simply a function of one variable, x. What happens if y becomes a function of both x and z? Maybe like: y=x2+z3+xz2 y = x^2 + z^3 + xz^2

What happens to my derivatives now?

Well when you differentiate wrt x, you treat z as if it were just a number (a constant):

dydx=2x+z2 \displaystyle \frac{dy}{dx} = 2x + z^2

and similarly for z:

dydz=3z2+2xz \displaystyle \frac{dy}{dz} = 3z^2 + 2xz


Obviously these are basic problems in MVC, there here so you start to see why its so called.
Linear algebra is basically what was in my first post, learning to deal with vectors and matrices in a more general way. It can be quite a difficult subject to learn but once you get the hang of it, it does tend to make sense.
Cexy
I don't think that an A Level student can understand general relativity in any meaningful sense, and certainly not in a summer. If you really wanted to be able to do all the maths, you'd have to learn:

Multivariable calculus
Linear algebra
Ordinary and partial differential equations
Differential geometry

Plus all of the prerequisites... and the prerequisites for the prerequisites.

General relativity is taught as a third year undergraduate course in Cambridge, and even then I don't think you do anything other than scrape the surface until the fourth year course.

You'd do much better reading popular science books (Brief History of Time, Elegant Universe, QED) in my opinion.


Yep, thanks - this is what i was prepared for.

I'm prepared to just get a little way into it though. I've got little to do and div curl F = 0's recommendation sounds good, so i can at least make a start.

I've already read Brief History of Time, Elegant Universe, QED and many more. I have a fairly good understanding on the topics, i just just wanted to start some of the mathematics.

Would i be best (if i were to truly be this sad) learning:

Multivariable calculus
Linear algebra
Ordinary and partial differential equations
Differential geometry

in this order?
Reply 8
Basically, the preliminaries of general relativity consist of teaching you how to differentiate things. Presumably if you've sat an A Level you can differentiate a scalar function of one variable, i.e. f(x). From there you need to differentiate functions of several variables f(x,y,z), then vector functions f(x), then you need to be able to differentiate matrices, and then tensors (which are like matrices, but even more so) and you want to differentiate them with respect to whatever the hell you like. Then throw into the mix the fact that space is curved, so the way you measure distances changes as you move around in space (how do you measure distance on a sphere? on a donut? on a coffee cup?) and then consider the fact that the way you measure distances changes over time, and in relation to the mass present in the space, which affects how the mass moves around, which then has another knock-on effect to the way that the space curves, ad infinitum.

As I said, I don't think you can learn it in a summer.
Reply 9
I'd learn linear algebra and multivariable/vector calculus at the same time, since they're so closely inter-related. When you have a decent enough grasp of calculus, you can start to use the techniques to solve differential equations.

If you are really dead set on trying to learn this stuff you'd do well to pick up a copy of "Mathematical Methods for Physics and Engineering" by Riley, Hobson and Bence. It starts at A Level or below, and works its way up to second/third year material.

Edit: You could try going here and then keep clicking on "Next"...
0 div curl F
Obviously these are basic problems in MVC, there here so you start to see why its so called.
Linear algebra is basically what was in my first post, learning to deal with vectors and matrices in a more general way. It can be quite a difficult subject to learn but once you get the hang of it, it does tend to make sense.


Thanks.

Yeh, i started looking at these after i made my original post. It seems interesting enough and your beginners tutorial is good :p: Is it the sort of thing i would learn in the first year of a Physics degree?

The book looks very good and in depth from the 'search inside' feature on amazon. Plus it's cheap - i will definately order.

This gives me something to look forward to this summer, even if i end up getting out of my depth eventually.
The best thing to study IMO is linear algebra, it applies to both SR and GR and many other areas of physics. The other topics do appear in GR but they don't mean anything unless your linear algebra has a good foundation.

The starting places of SR and GR is generally learning the difference between contravariant and covariant vectors, how they relate to each other and how they relate to "proper observables". This would be a good place to start, and also the idea of lorentz invariance and lorentz invariant quantites (sometimes called 4-scalars or lorentz scalars).
Cexy
I'd learn linear algebra and multivariable/vector calculus at the same time, since they're so closely inter-related. When you have a decent enough grasp of calculus, you can start to use the techniques to solve differential equations.

If you are really dead set on trying to learn this stuff you'd do well to pick up a copy of "Mathematical Methods for Physics and Engineering" by Riley, Hobson and Bence. It starts at A Level or below, and works its way up to second/third year material.

Edit: You could try going here and then keep clicking on "Next"...


Thanks (for not just laughing in my face that i want to learn this stuff).

Obviously i realise that learning 'General Relativity' in one summer is far-fetched, i suppose my original title is misleading. I just want to at least make a start.

The book looks good. As it's an actual textbook it's quite pricey, but if i can use it in my degree anyway i'll give it a look.
Okay thanks for your help guys.

I'm going to get Mathematical Methods for Physics and Engineering and Relativity Demystified. I'll start on the maths you've stated. Then after a while see how far this gets me into Relativity Demystified.

I'm assuming these maths topics will come up in first year anyway so at the very least it might give me some preperation of what to expect and kill some time.
I recommend reading "Schaum's Outline of Vector Analysis" beforehand, to cover mathematical prerequisites. And Hartle's book Gravity: And introduction to Einstein's General Relativity. It presents a good, intuitive picture for beginners, as opposed to something like De Felice/Clarke. McMahon tries to do too much, without key focus on the principles at hand, I find. But it does as promised, and familiarises the beginner with some of the mathematics, though in a somewhat superficial way outside of the worked examples, which are really the only element to the book.
Symbioticenigma
I recommend reading "Schaum's Outline of Vector Analysis" beforehand, to cover mathematical prerequisites. And Hartle's book Gravity: And introduction to Einstein's General Relativity. It presents a good, intuitive picture for beginners, as opposed to something like De Felice/Clarke.


Okay, i'll have a look into those too. "Mathematical Methods for Physics and Engineering" seems fairly comprehensive, but i'll bare those in mind. "Schaum's Outline of Vector Analysis" is certainly cheap enough, i would have to have a quick look at the other before i buy.

And thanks for making your first post in my thread :smile:
Reply 16
Possible to self teach anything though you might be pressed for time in just a summer. I think the biggest caveat here is that to teach yourself things that are mathematical in nature you really need to put in the effort to do practice questions. It's not enough to merely read chapter after chapter in a text book and nod your head as you go along, you have to do the questions at the back of each chapter and that's the really time consuming part and also the part that is hardest to self-motivate for. If you do go ahead with it make sure you use text books that include lots of practice questions, solved examples AND answers (if not full solutions) to questions. (Anything in the Schaum's series is particularly good in this regard but you won't get much than the bare bones with them).

Also never ever buy text books. Always borrow. Though "Relativity Demystified" is relatively cheap I think.
schrodinger's cat
Okay, i'll have a look into those too. "Mathematical Methods for Physics and Engineering" seems fairly comprehensive, but i'll bare those in mind. "Schaum's Outline of Vector Analysis" is certainly cheap enough, i would have to have a quick look at the other before i buy.

And thanks for making your first post in my thread :smile:

It is indeed an excellent book, I used it to teach myself the Mathematics up to Tensor Analysis in order to prepare for GR. The experience gained of Vectors would no doubt serve as useful when you come to do EM during your early undergraduate period, with the same book going on to Tensors. But most standard GR texts, including Hartle, have a brief discussion on Riemannian geometry. It is just a case of choosing an introductory text that places it in the best physical context, since a page of lemmas is daunting for the beginner.
And yes, I could not resist a thread on GR.
KwungSun
Possible to self teach anything though you might be pressed for time in just a summer. I think the biggest caveat here is that to teach yourself things that are mathematical in nature you really need to put in the effort to do practice questions. It's not enough to merely read chapter after chapter in a text book and nod your head as you go along, you have to do the questions at the back of each chapter and that's the really time consuming part and also the part that is hardest to self-motivate for. If you do go ahead with it make sure you use text books that include lots of practice questions, solved examples AND answers (if not full solutions) to questions. (Anything in the Schaum's series is particularly good in this regard but you won't get much than the bare bones with them).

Also never ever buy text books. Always borrow. Though "Relativity Demystified" is relatively cheap I think.


Yes, i realise the maths (and doing questions) is the most important part - and where i'm most likely to fail in motivation, but i'd like to give it a try. "Mathematical Methods for Physics and Engineering" apparently has many questions and there is also a solution book you can buy with full working. the Schaum's series do look temptingly cheap :p: i might buy a few if i get anywhere with this to supplement my other books.

"Mathematical Methods for Physics and Engineering" is the only expensive book here. TBH i'm not too fussed on spending a bit of money - and if it truly lasts me the next 3 or 4 years it'll be worth the value of no hassle trying to 'borrow' it, especially when i'm not even at uni yet.
Reply 19
schrodinger's cat
Okay thanks for your help guys.

I'm going to get Mathematical Methods for Physics and Engineering and Relativity Demystified. I'll start on the maths you've stated. Then after a while see how far this gets me into Relativity Demystified.

I'm assuming these maths topics will come up in first year anyway so at the very least it might give me some preperation of what to expect and kill some time.

I'm doing something similar to what you are trying to do. Well, I'm not self-teaching physics/maths over the summer specifically for GR but just so that I can get a mini-headstart into the material.
The cool thing is that I have the Mathematical Methods for .... book. It is amazing, almost as cool at the bible. Highly recommend it. The other thing I would recommend is going through the first couple of chapters. I've discovered that I was taught a lot of crap at a-level and the textbook is more in depth and also contains some stuff not taught in the further maths syllabus (at least with my exam board anyway). The questions can be **** hard at times so the student solutions companion is not a bad idea.
Oh and the books is massive, so don't be disheartened if you don't make any real progress into it. It took me about 2 weeks to cover the first three chapters which is all stuff I've done in school. :s-smilie:
Anyway time for sleep...

PS: Do the cat jokes ever get old? :p: