Uncovering the Mystery of Centrifugal Forces: Hafele and Keating Experiment

In summary, Laurent introduces the concept of using a rotating earth as a reference frame to study the effects of centrifugal forces on space ships. This leads to the discussion of the principle of inertia and the role of distant masses as the cause of inertia. The relationship between the motion of the ships and the rotating earth is further explained, and the effect of gravity on selecting an inertial frame is addressed.
  • #1
matheinste
1,068
0
Hello all.

From Laurent – Introduction to Spacetime. Referring to the Hafele and Keating experiment.

---Let us neglect gravitation and picture the Earth as a merry-go-round all alone in empty space. The rim of the merry-go-round corresponds to the equator. Let us further assume that two space ships are flying along the rim in opposite directios with such a speed that they circle once relative to the merry-go-round while it rotates one turn. This has the effect that centrifugal forces are felt on board one of the ships but not on board the other one.-----

Why! Obviously some fundamental law or principle is involved.

Matheinste.
 
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  • #2
Imagine the motion of each ship as seen by an inertial observer watching the Earth rotate. The one going in the same direction as the spinning Earth clearly undergoes circular motion (and feels a centrifugal force), but the one going against the Earth's rotation is really just sitting there with respect to the inertial frame.
 
  • #3
Hello Doc Al.

As simple as that. Thanks.

Matheinste.
 
  • #4
matheinste said:
Hello all.

From Laurent – Introduction to Spacetime. Referring to the Hafele and Keating experiment.

---Let us neglect gravitation and picture the Earth as a merry-go-round all alone in empty space. The rim of the merry-go-round corresponds to the equator. Let us further assume that two space ships are flying along the rim in opposite directios with such a speed that they circle once relative to the merry-go-round while it rotates one turn. This has the effect that centrifugal forces are felt on board one of the ships but not on board the other one.-----

Why! Obviously some fundamental law or principle is involved.

Matheinste.

The principle of inertia. Einstein addressed a similar problem in this paper: http://hem.bredband.net/b153434/Works/Einstein.htm [Broken]

As a local system, there is no cause to be found for the centrifugal forces. Einstein called this an "inherent epistemological defect" in classical physics, and in SR. And he points out that the cause must lie outside the system, ie distant masses as the cause of inertia.

I've asked questions about this on this board, but no one seemed interested in it.

Al
 
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  • #5
Doc Al said:
Imagine the motion of each ship as seen by an inertial observer watching the Earth rotate. The one going in the same direction as the spinning Earth clearly undergoes circular motion (and feels a centrifugal force), but the one going against the Earth's rotation is really just sitting there with respect to the inertial frame.
I don't suppose he is sitting, he has the same absolute speed with respect the inertial frame as the other, and his speed with respect to the surface of the Earth could be the double as the other one.
 
  • #6
Pippo said:
I don't suppose he is sitting, he has the same absolute speed with respect the inertial frame as the other, and his speed with respect to the surface of the Earth could be the double as the other one.
The speeds are defined in the original quote. They each circle once with respect to the Earth in the time it takes the Earth to rotate once. So with respect to the inertial frame, one will have speed 2ωR, the other 0.
 
  • #7
Doc Al said:
The speeds are defined in the original quote. They each circle once with respect to the Earth in the time it takes the Earth to rotate once. So with respect to the inertial frame, one will have speed 2ωR, the other 0.

Perhaps I am still missing something, but what happen if the Earth stops rotating ?
 
  • #8
Pippo said:
Perhaps I am still missing something, but what happen if the Earth stops rotating ?
If the ships maintain their speed with respect to the Earth's surface and the Earth stops rotating, then the ships will have the same speed ωR but in opposite directions. Of course this in an entirely different situation than that described by Laurent.
 
  • #9
How does neglecting gravity affect the selection of an inertial frame here?
 
  • #10
With gravity, either ship would be in an inertial frame (assuming they are at the right altitude for geosynchronous robit; around 22,365 mi). Without it, of course, neither is.
 

1. What is the Hafele and Keating Experiment?

The Hafele and Keating Experiment, also known as the "Clocks in Flight" experiment, was conducted in 1971 by scientists Joseph C. Hafele and Richard E. Keating. It was designed to test the effects of time dilation and gravitational forces on clocks that were traveling at high speeds and different altitudes.

2. How does the Hafele and Keating Experiment relate to centrifugal forces?

The Hafele and Keating Experiment showed that as objects move at high speeds, they experience time dilation, meaning their internal clocks run slower than stationary clocks. This can be attributed to the centrifugal forces acting on the objects, which are caused by their acceleration and velocity.

3. What were the results of the Hafele and Keating Experiment?

The results of the experiment confirmed the theories of relativity, specifically the time dilation effect predicted by Einstein's theory of special relativity. The clocks that traveled eastward around the Earth had slower times compared to the stationary clocks, while the clocks that traveled westward had faster times.

4. Why is the Hafele and Keating Experiment important in understanding centrifugal forces?

The Hafele and Keating Experiment provided concrete evidence for the existence of time dilation and the relationship between velocity and gravitational forces. This has important implications in understanding the effects of centrifugal forces on objects in motion.

5. How does the Hafele and Keating Experiment impact modern science and technology?

The Hafele and Keating Experiment has contributed to the development of technologies such as GPS, which rely on the principles of relativity and time dilation to accurately measure and track locations on Earth. It also continues to be used in further research on the effects of centrifugal forces and the theories of relativity.

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