Chapter 37 - Relativity Flashcards
Newton’s Laws are valid in…
2
Inertial frame
Gallilean-Newtonian Coordinate System
GN Coordinate Systems and inertial frames have * * relative to a fixed system of coordinates
No acceleration
Is the earth an inertial frame?
No
What is a ‘fixed’ coordinate system?
So called ’fixed’ stars are often taken as a frame of reference (although fixed stars move as well)
What is the Aether?
The medium that light (an EM wave) passes through when travelling through space.
How do Newton’s Laws hold in the Aether?
They would hold exactly for the observer moving without acceleration relative to the aether.
What is a Michelson Inferometer?
A device sensitive enough to detect the movement of the earth relative to the aether.
It gave no result.
How did Lorentz and Fitzgerald explain the null result from the Michelson Inferometer?
A contraction of a body along its direction of motion through the aether by a factor of:
(1-v^2/c^2)^(-1/2)
There was no justification for this contraction.
By comparing mechanics with electromagnetism, Einstein concludes that this phenomena possess no properties corresponding to absolute rest, only * * is important.
Relative motion
Einstein’s first postulate of Special Relativity:
The laws of physics are the same in all coordinate systems (inertial frames) which move uniformly relative to each other.
IE. There is no preferred reference frame
Einstein’s second postulate of Special Relativity:
The velocity of light in empty space is the same in all reference frames and is independent of both the emitting body and the observer.
What does Einstein’s Second Postulate imply?
It is impossible for an inertial observer to travel at the speed of light.
