Earth as Inertial Ref. Frame: Test Relativity's Precision

In summary: So, in summary, special relativity is a well-tested theory in physics that postulates that the speed of light is the same for all observers in inertial reference frames. This has been tested with great precision and has led to the discovery of time dilation and other effects. However, the Earth is not an inertial reference frame due to its rotation and revolution, and this can have an impact on experiments such as the Michelson-Morley experiment. While the effects of this acceleration may be small and negligible in some experiments, they can still be observed in others, such as the Sagnac interferometer.
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pixel
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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?
 
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  • #2
pixel said:
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
pixel said:
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.
 

FAQ: Earth as Inertial Ref. Frame: Test Relativity's Precision

1. What is an inertial reference frame?

An inertial reference frame is a coordinate system that remains at rest or moves with constant velocity in a straight line, as described by Newton's first law of motion. In other words, it is a frame of reference that is not experiencing any acceleration.

2. How does using Earth as an inertial reference frame test relativity's precision?

Since Earth is rotating and orbiting around the sun, it is not a perfect inertial reference frame. However, by accounting for the Earth's motions and using it as an approximation of an inertial reference frame, we can test the principles of relativity with high precision.

3. What are the main findings of using Earth as an inertial reference frame to test relativity?

One of the main findings is the confirmation of time dilation, which is the slowing of time in a moving frame of reference. This has been demonstrated through experiments such as the Hafele-Keating experiment, where atomic clocks were flown on airplanes in opposite directions.

4. How does the concept of space-time come into play in using Earth as an inertial reference frame?

The theory of relativity states that space and time are intertwined and form a four-dimensional continuum known as space-time. By using Earth as an inertial reference frame, we can observe how space and time are affected by the Earth's motions, thus providing evidence for the theory of relativity.

5. Can using Earth as an inertial reference frame help us understand the concept of gravity?

Yes, it can. The theory of relativity also explains gravity as the curvature of space-time caused by massive objects. By using Earth as an inertial reference frame and observing its interactions with other celestial bodies, we can gain a better understanding of the concept of gravity and how it affects the movement of objects in the universe.

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