In modern physics it is also known as theory of relativity.
The theory of relativity, or simply relativity in physics, usually encompasses two theories by Albert Einstein:
Concepts introduced by the theories of relativity include:
- Measurements of various quantities are relative to the velocities of observers. In particular, space contracts and time dilates.
- Spacetime: space and time should be considered together and in relation to each other.
- Space is a physical entity that can be changed, space is not just nothing, space can affect mass (gravity)
- The speed of light is nonetheless invariant, the same for all observers.
- The term "theory of relativity" was based on the expression "relative theory" (German: Relativtheorie) used in 1906 by Max Planck, who emphasized how the theory uses the principle of relativity. In the discussion section of the same paper, Alfred Bucherer used for the first time the expression "theory of relativity" (German: Relativitätstheorie)
Source adapted from:
Theory of relativity. (2015, November 21). In Wikipedia, The Free Encyclopedia. Retrieved 08:23, November 22, 2015, from https://en.wikipedia.org/w/index.php?title=Theory_of_relativity&oldid=691723653