# General relativity vs special relativity

• Starlover
In summary, according to special relativity, a change in speed results in a change in length contraction as well as in a change in time dilation. According to general relativity, the effects of constant acceleration - a change in speed - cannot be distinguished from the effects of gravitation.

#### Starlover

Hello, Everybody!

I'm new to the board, and am happy to have found you!

I have six questions I can't seem to find the answers to, either in books or online -- yet I know the answers are out there! I'll post each question in a separate thread, and hope that someone who knows far more than I do will be generous enough to assist!

My first question concerns general relativity vs. special relativity. The question is: Does the spacetime warp created by velocity ultimately hark back to general relativity? In other words, is the gravity created by acceleration and velocity actually creating general relativity?

Starlover said:
My first question concerns general relativity vs. special relativity. The question is: Does the spacetime warp created by velocity ultimately hark back to general relativity? In other words, is the gravity created by acceleration and velocity actually creating general relativity?
That's simply wrong. No space-time warp is caused by acceleration or velocity!

Whether or not spacetime is flat is a frame invariant thing. Relative velocity does not alter the curvature of spacetime.

Starlover said:
[..] Does the spacetime warp created by velocity ultimately hark back to general relativity? In other words, is the gravity created by acceleration and velocity actually creating general relativity? [..]
Hi, as already mentioned, your questions contain several errors. But it's still possible to guess what you likely meant:

According to special relativity, a change in speed results in a change in length contraction as well as in a change in time dilation.
The basic idea of general relativity was that the effects of constant acceleration - a change in speed - cannot be distinguished from the effects of gravitation. In that way, predictions of special relativity were helpful in the development of a theory of gravitation.

Einstein explained it for example here (in particular from chapter 20): http://www.bartleby.com/173/

Starlover said:
Hello, Everybody!

I'm new to the board, and am happy to have found you!

I have six questions I can't seem to find the answers to, either in books or online -- yet I know the answers are out there! I'll post each question in a separate thread, and hope that someone who knows far more than I do will be generous enough to assist!

My first question concerns general relativity vs. special relativity. The question is: Does the spacetime warp created by velocity ultimately hark back to general relativity? In other words, is the gravity created by acceleration and velocity actually creating general relativity?

I'm not sure how to interpret this. "The spacetime warp" could maybe be the Riemann tensor, but then "created by velocity" doesn't make any sense in this context. I have a feeling that we are assigning different meanings to words. This makes communication difficult. If I were to reply with some textbook responses about what GR is, I suspect we'd have the same difficulty in the opposite directions.

Cold you ask something concrete? For instance, would comparing the gravitational effects caused by the low-speed fly-by of a massive body in Newtonian theory to the results that GR predicts for a high-speed ultra-relativistic flyby be helpful to you in answering your question? There is a paper on that I could refer you to, if the answer would be helpful.

## 1. What is the difference between general relativity and special relativity?

General relativity describes the effects of gravity on the fabric of space-time, while special relativity describes the relationship between space and time in the absence of gravity.

## 2. How do the principles of special relativity apply to everyday life?

The principles of special relativity are applicable to everyday life in the sense that they govern the behavior of objects moving at high speeds, such as in particle accelerators or when using GPS technology.

## 3. Does general relativity replace special relativity?

No, general relativity does not replace special relativity. General relativity is a more comprehensive theory that includes the principles of special relativity, but also explains the effects of gravity.

## 4. What are some practical applications of general relativity?

General relativity has been used to accurately predict the behavior of planets in our solar system, to explain the phenomenon of gravitational lensing, and to inform the development of technologies such as GPS and satellite communications.

## 5. Is it possible to prove or disprove the theories of general and special relativity?

While it is possible to test and verify the predictions made by general and special relativity, it is not possible to definitively prove or disprove these theories. They are currently the most widely accepted explanations for the behavior of space and time, but future scientific advancements may lead to new understandings or modifications of these theories.