How good an inertial reference frame is the Earth?

  • I
  • Thread starter pixel
  • Start date
  • #1
541
145

Main Question or Discussion Point

Special relativity is one of the most tested theories in physics. A central postulated of SR is that the speed of light is the same for all observers in inertial reference frames, and this leads to time dilation and the other effects that have been tested with a high degree of precision.

We know, however, that the earth is rotating and revolving around the sun, the sun is revolving around the galactic center etc. So at any given time there is a net acceleration of any earthbound reference frame and it is therefore not strictly inertial. Is this such a small effect as to be totally negligible for testing of SR, at least to the precision of testing to date?

I'm thinking in particular of the Michelson-Morley experiment. If the lab frame of reference has a net acceleration in some direction, wouldn't the speed of light be different parallel and perpendicular to that direction? Is this effect totally negligible?
 

Answers and Replies

  • #2
A.T.
Science Advisor
10,382
2,046
We know, however, that the earth is rotating and revolving around the sun, the sun is revolving around the galactic center etc
The Earth's surface has 1g upwards proper acceleration. That's what mostly makes it non-inertial in the relativistic sense.
 
  • #3
29,557
5,884
Is this such a small effect as to be totally negligible for testing of SR, at least to the precision of testing to date?

I'm thinking in particular of the Michelson-Morley experiment. If the lab frame of reference has a net acceleration in some direction, wouldn't the speed of light be different parallel and perpendicular to that direction? Is this effect totally negligible?
It depends on the specific experimental set up. The MMX design is simply not sensitive to the rotation, and in the horizontal plane it is not sensitive to the uniform vertical acceleration. A Sagnac interferometer is sensitive to the rotation. Other experiments are sensitive to the vertical acceleration.
 

Related Threads on How good an inertial reference frame is the Earth?

  • Last Post
Replies
7
Views
65K
Replies
14
Views
5K
Replies
3
Views
871
  • Last Post
Replies
13
Views
2K
Replies
3
Views
6K
Replies
12
Views
1K
  • Last Post
Replies
15
Views
5K
  • Last Post
Replies
4
Views
2K
  • Last Post
Replies
8
Views
2K
  • Last Post
Replies
15
Views
3K
Top