Thorne's error in explaining gravitational time dilation

In summary, Thorne uses a thought experiment to explain gravitational time dilation and the equivalence principle in Box 2.4 of his book "Black Holes & Time Warps." He describes a scenario with two identical clocks dropped in a gravitational field from different heights and how this results in a gravitational Doppler shift. However, this thought experiment is not a valid basis for discussion as it is presented in a pop science book, not a textbook or peer-reviewed paper.
  • #1
Guillermo Navas
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TL;DR Summary
Error in explaining gravitational time dilation using the equivalence principle and the Doppler effect.
In Box 2.4 of the book "Black Holes & Time Warps" by Kip S. Thorne, he explains gravitational time dilation using the equivalence principle. For this he uses an experiment thought analogous to the one used by Einstein in 1911 to postulate the existence of a gravitational Doppler shift, but slightly modifying the initial conditions.

Thorne's thought experiment is as follows: consider two identical clocks that are dropped in free fall into a gravitational field from different heights. Light pulses are sent from the highest clock to the lowest clock. The clock on the ceiling emits its first pulse of light when it begins its fall, while the lower clock begins its free fall when it receives the first pulse of light. The detailed explanation can be seen in the image on the Box 2.4 pages, Thorne says: “Because the ceiling clock was dropped before the floor clock, its downward speed is always greater than that of the floor clock (diagram b); that is, it moves toward the floor clock. This implies that the floor clock will see the ceiling clock’s light pulses Doppler-shifted (Box 2.3); that is, it will see them arrive more closely spaced in time than the time between its own ticks”.

Can you see which the error is?
 

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  • #2
Guillermo Navas said:
the book "Black Holes & Time Warps" by Kip S. Thorne

...is not a textbook or peer-reviewed paper. It's a pop science book. So it's not a valid basis for PF discussion.

Thread closed.
 

Related to Thorne's error in explaining gravitational time dilation

What is Thorne's error in explaining gravitational time dilation?

Thorne's error in explaining gravitational time dilation is a mistake made by physicist Kip Thorne in his explanation of how gravity affects the passage of time. Thorne proposed that time slows down in the presence of a strong gravitational field, but his explanation was later found to be incorrect.

What did Thorne propose about gravitational time dilation?

Thorne proposed that time slows down in the presence of a strong gravitational field, meaning that clocks would run slower near massive objects like planets or black holes. This was based on Einstein's theory of general relativity.

What was the problem with Thorne's explanation?

The problem with Thorne's explanation is that it did not take into account the effects of acceleration. In reality, it is not gravity itself that causes time dilation, but rather the acceleration caused by gravity. This was later corrected by physicist John Archibald Wheeler.

How does acceleration affect gravitational time dilation?

Acceleration is a key factor in gravitational time dilation. The greater the acceleration, the greater the time dilation. This means that objects in a strong gravitational field will experience more time dilation due to the acceleration caused by gravity.

What is the correct explanation for gravitational time dilation?

The correct explanation for gravitational time dilation is that it is caused by the acceleration of objects in a strong gravitational field. This was first proposed by physicist John Archibald Wheeler and is now widely accepted as the correct explanation for this phenomenon.

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