# What is the difference between special and general theory ?

• sciboudy
In summary: Yes, definitely get a book to start with. There are many great books on special relativity, but I would recommend either An Illustrated Guide to Relativity by Takeuchi or It's About Time: Understanding Einstein's Relativity by Mermin.
sciboudy
what is the difference between general theory and special theory of relativity ?

The Einstein Field Equation.

can you Explain more ? i need to learn

This may be too technical of an answer,but in special relativity, the geometry of space-time is Lorentzian and globally flat.

In general relativity, the geometry of space-time is still Lorentzian, but it's no longer globally flat. The geometry of space-time is locally flat if you consider a small enough region, just as the surface of the Earth is locally flat (within some specified accuracy) if one considers a small enough piece of land. "Locally flat" doesn't mean the curvature dissapears, it just means that you can ignore it for practical purposes like surveying.

GR also has Einstein's field equations, which relate the curvature of space-time to the matter and energy present.

If you need or want a defintion of "Lorentzian" geometry, just ask, though it might be helpful to have some idea of the level at which you want the answer.

really i need definition of lorentzian geometry and
what is the meaning of globally and locally because I'm not good at English

The special theory is a theory without gravity.

The general theory of relativity is a theory of gravity (and I have no idea why it is called "general relativity" instead of "Einstein's theory of gravity").

so general theory discuses the relation between space time and gravity
and special discuses the space time relation
so G theory more difficult than special
so i will focus special

sciboudy said:
so general theory discuses the relation between space time and gravity
and special discuses the space time relation
so G theory more difficult than special
so i will focus special

The general theory simply says spacetime is gravity. Since mass generates gravity, gravity is changed by moving masses, which means that spacetime is curved.

Yes, it's good to start with the special theory. There spacetime is flat and unchanging, since there is no gravity.

atyy said:
The general theory simply says spacetime is gravity. Since mass generates gravity, gravity is changed by moving masses, which means that spacetime is curved.

Yes, it's good to start with the special theory. There spacetime is flat and unchanging, since there is no gravity.

before i start in spatial Explain how mass generates gravity ? how are you Concluded that mean
spacetime curved by moving masses?

sciboudy said:
before i start in spatial Explain how mass generates gravity ? how are you Concluded that mean
spacetime curved by moving masses?

Gravity is the force of attraction between masses. We think of a mass generating the gravitational field, which acts on another mass, attracting it to the first mass.

Now, what do we mean by spacetime? We mean something that we measure by rulers and clocks. If our ruler has mass, it will be attracted by other masses, and will be bent, so spacetime will appear curved in the presence of gravity.

atyy said:
Gravity is the force of attraction between masses. We think of a mass generating the gravitational field, which acts on another mass, attracting it to the first mass.

Now, what do we mean by spacetime? We mean something that we measure by rulers and clocks. If our ruler has mass, it will be attracted by other masses, and will be bent, so spacetime will appear curved in the presence of gravity.

good i think i will begin by special theory ? although i think general theory is more interesting

sciboudy said:
good i think i will begin by special theory ? although i think general theory is more interesting

Yes. Definitely start with the special theory. It is a bad idea to start with the general theory. Mastering the special theory is the best way to start understanding the general theory:)

i heard that michlson experiment helps Einstien to begin in the theory of special
what is this Experiment ? and HOw it helped him ?

sciboudy said:
i heard that michlson experiment helps Einstien to begin in the theory of special
what is this Experiment ? and HOw it helped him ?

This is the stage where you really want to get a book. You're not going to be able to learn SR by asking people questions on web forums. Some special relativity books that I like are (from easiest to hardest):

Takeuchi, An Illustrated Guide to Relativity
Mermin, It's About Time: Understanding Einstein's Relativity
Taylor and Wheeler, Spacetime Physics

bcrowell said:
This is the stage where you really want to get a book. You're not going to be able to learn SR by asking people questions on web forums. Some special relativity books that I like are (from easiest to hardest):

Takeuchi, An Illustrated Guide to Relativity
Mermin, It's About Time: Understanding Einstein's Relativity
Taylor and Wheeler, Spacetime Physics

okay i need easy book or some books

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bcrowell said:
This is the stage where you really want to get a book. You're not going to be able to learn SR by asking people questions on web forums. Some special relativity books that I like are (from easiest to hardest):

Takeuchi, An Illustrated Guide to Relativity
Mermin, It's About Time: Understanding Einstein's Relativity
Taylor and Wheeler, Spacetime Physics

and I love discuses with people now i thin k they will help me ..

sciboudy said:
and I love discuses with people now i thin k they will help me ..

Well, yes, folks here WILL help you but I think Ben's point in saying that now is the time you need a book is that by JUST asking questions here, you will jump around too much. Get a book and read the whole thing through so that you get ALL of the aspects.

As you are reading, if you have questions then of course it is a good idea to ask them here.

Good luck.

okay thank can you give link for simple book of relativity special ...

I suggest that you look up the books Ben listed on-line (Amazon will probably have reviews of them) and see if one of them would be right for your level of understanding of math. Doing that will lead you to other titles that you might want to explore to see if they are right for you.

phinds said:
I suggest that you look up the books Ben listed on-line (Amazon will probably have reviews of them) and see if one of them would be right for your level of understanding of math. Doing that will lead you to other titles that you might want to explore to see if they are right for you.

i will do when i finish my Exams i will search for find good book
thank you

Usually, I need many, many books, since one book will explain somethings well and other things not so well (at least for my background). So it's good to buy maybe one or two cheap books, but otherwise visit a good library, or have some free stuff on the web to download, otherwise it'll be pretty expensive. Here are some things from the web, ordered roughly according to difficulty, though there's no reason not to jump around and cross-check that they all say the same thing. Tatsu Tekeuchi's and Michael Fowler's materials are probably the ones to sit down with and work through carefully.

http://www.einstein-online.info/elementary
http://www.phy.syr.edu/courses/modules/LIGHTCONE/
http://www.phys.vt.edu/~takeuchi/relativity/
http://galileo.phys.virginia.edu/classes/252/
http://people.maths.ox.ac.uk/nwoodh/sr/index.html
http://www.damtp.cam.ac.uk/research/gr/members/gibbons/gwgPartI_SpecialRelativity2010.pdf
http://ocw.mit.edu/courses/physics/8-033-relativity-fall-2006/lecture-notes/
http://www.bartleby.com/173/
http://www.fourmilab.ch/etexts/einstein/specrel/www/

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atyy said:
Usually, I need many, many books, since one book will explain somethings well and other things not so well (at least for my background). So it's good to buy maybe one or two cheap books, but otherwise visit a good library, or have some free stuff on the web to download, otherwise it'll be pretty expensive. Here are some things from the web, ordered roughly according to difficulty, though there's no reason not to jump around and cross-check that they all say the same thing. Tatsu Tekeuchi's and Michael Fowler's materials are probably the ones to sit down with and work through carefully.
thank you very much very good webs

Just for completeness, it doesn't look like anyone actually defined the term Lorentzian (in reference to a manifold) for you? Essentially, it means that the metric has a signature (- + + +) or (+ - - -) if you like. The crucial point is that it is a (3,1) spacetime, as opposed to something like (- - + +) or (+ + - -) which would be a (2,2) spacetime. When we break the space/time symmetry, we can identify a (3,1) spacetime by saying there are 3 spatial dimensions and 1 time dimension, which is, for practicality, the definition of a Lorentzian spacetime. In contrast, a (2,2) spacetime would have two time-like dimensions and two space-like dimensions.

Nabeshin said:
Just for completeness, it doesn't look like anyone actually defined the term Lorentzian (in reference to a manifold) for you? Essentially, it means that the metric has a signature (- + + +) or (+ - - -) if you like. The crucial point is that it is a (3,1) spacetime, as opposed to something like (- - + +) or (+ + - -) which would be a (2,2) spacetime. When we break the space/time symmetry, we can identify a (3,1) spacetime by saying there are 3 spatial dimensions and 1 time dimension, which is, for practicality, the definition of a Lorentzian spacetime. In contrast, a (2,2) spacetime would have two time-like dimensions and two space-like dimensions.

thank you very much

## What is the difference between special and general theory?

The special theory of relativity, proposed by Albert Einstein in 1905, is a theory that describes the relationship between space and time for objects moving at constant speeds. It is based on two postulates: the laws of physics are the same for all observers in uniform motion, and the speed of light is constant for all observers regardless of their relative motion. On the other hand, the general theory of relativity, proposed by Einstein in 1915, is a more comprehensive theory that explains the effects of gravity on the structure of space and time. It expands on the principles of the special theory to include non-uniform motion and acceleration.

## How do special and general theory differ in their treatment of gravity?

The special theory of relativity does not account for the effects of gravity, while the general theory explains gravity as the curvature of space-time caused by the presence of mass and energy. In the special theory, gravity is treated as a fictitious force, while in the general theory it is a fundamental property of space and time.

## Which theory is more widely applicable in real-world scenarios?

The general theory of relativity is more widely applicable in real-world scenarios as it can account for gravity and non-uniform motion, while the special theory is limited to objects moving at constant speeds in a straight line.

## What are the major implications of special and general theory in our understanding of the universe?

The special theory of relativity revolutionized our understanding of space and time, challenging the Newtonian concepts of absolute space and time. The general theory expanded on this by providing a framework for understanding the effects of gravity and the behavior of massive objects on the structure of space-time. Both theories have had a significant impact on our understanding of the universe and have been validated through numerous experiments and observations.

## Are there any current debates or controversies surrounding special and general theory?

Theories of relativity have been widely accepted and confirmed through experiments and observations, but there are still some ongoing debates and controversies. For example, there are ongoing discussions about the exact nature of gravity and its relationship to other fundamental forces, and attempts to reconcile the theories of relativity with quantum mechanics. Additionally, some scientists are exploring alternative theories of gravity that could potentially challenge the principles of special and general relativity.

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