I asked Google Bard AI:
why length contraction in special relativity ceases when motion stop.

Bard AI answer:

Length contraction in special relativity is a consequence of the fact that the speed of light is the same in all inertial frames of reference. This means that if you are moving at a constant speed, and you measure the length of an object that is also moving at a constant speed in the same direction as you, the length of the object will appear shorter to you than it would if you were both at rest.

When the motion stops, the relative velocity between the object and the observer becomes zero, and the length contraction effect disappears. This is because the length of the object is no longer being measured in the moving frame of reference, but rather in the rest frame of the object.

The length contraction rule is given by the following equation:

L = L0 √1 - v^2 / c^2

where:

L is the length of the object as measured in the moving frame of reference
L0 is the length of the object as measured in the rest frame of the object
v is the relative velocity between the object and the observer
c is the speed of light

As you can see, the length contraction effect is inversely proportional to the square of the relative velocity. This means that the smaller the relative velocity, the less pronounced the length contraction effect will be. When the relative velocity is zero, the length contraction effect disappears altogether.

I hope this explanation is helpful. Let me know if you have any other questions.

On Tuesday, July 18, 2023 at 12:44:27 PM UTC-3, Richard Hertz wrote:
> I asked Google Bard AI:
> why length contraction in special relativity ceases when motion stop.
>
> Bard AI answer:
>
> Length contraction in special relativity is a consequence of the fact that the speed of light is the same in all inertial frames of reference. This means that if you are moving at a constant speed, and you measure the length of an object that is also moving at a constant speed in the same direction as you, the length of the object will appear shorter to you than it would if you were both at rest.
>
> When the motion stops, the relative velocity between the object and the observer becomes zero, and the length contraction effect disappears. This is because the length of the object is no longer being measured in the moving frame of reference, but rather in the rest frame of the object.
>
> The length contraction rule is given by the following equation:
>
> L = L0 √1 - v^2 / c^2
>
> where:
>
> L is the length of the object as measured in the moving frame of reference
> L0 is the length of the object as measured in the rest frame of the object
> v is the relative velocity between the object and the observer
> c is the speed of light
>
> As you can see, the length contraction effect is inversely proportional to the square of the relative velocity. This means that the smaller the relative velocity, the less pronounced the length contraction effect will be. When the relative velocity is zero, the length contraction effect disappears altogether.
>
> I hope this explanation is helpful. Let me know if you have any other questions.

It needs some heavy "tuning". This is wrong: "This means that if you are moving at a constant speed, and you measure the length of an object that is also moving at a constant speed in the same direction as you, the length of the object will appear shorter to you than it would if you were both at rest.°

A complementary question to Bard AI: clock time dilation when moving is permanent?

ANSWER:

No, time dilation when moving is not permanent. It is only a relative difference in the rate at which time passes between two observers in different frames of reference. If the moving clock were to slow down and come to rest, the time dilation would disappear.

The amount of time dilation depends on the relative velocity between the two observers. The faster the relative velocity, the greater the time dilation. However, even at speeds close to the speed of light, the time dilation is not infinite.

For example, if a clock were to travel at 99% of the speed of light for one year, it would only experience about 7 months of time dilation. This means that when the clock returned to Earth, it would be about 5 months younger than a clock that had remained on Earth.

Time dilation is a real and observable phenomenon, but it is not something that we would notice in everyday life. The effects of time dilation only become significant at speeds close to the speed of light.