# Time & Gravity in Rotating Faster Than Light?

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• deedee6905
In summary, if a person is rotating on a vertical axis from head to toe like the Earth or quasar, distant stars traveling across the sky may eventually appear to be traveling faster than the speed of light due to the coordinate speed of light and not the true physical restriction. This is true for all stars except for those on the celestial equator, and the number of stars that could potentially fall within this limit is estimated to be around 80 in the observable universe. Additionally, time in a rotating frame of reference is shared with the clocks in an inertial frame of reference, making it inconvenient to use.
deedee6905
TL;DR Summary
If the earth rotates faster, distant stars traveling across the sky would eventually look like they are traveling faster than the speed of light. From the distant star's perspective, we are just rotating like crazy. How would time and gravity change for the two reference points of view if the speed of light can't be exceeded?
If a person was rotating on a verticle axis from head to toe like the Earth or quasar. If nothing can go faster than light, from the person's perspective looking at the stars traveling across the night sky, if you increase the rotation of the earth, stars further than a certain critical distance will have to appear to be traveling faster than the speed of light in the sky. The person on Earth wouldn't know that he is rotating. They would think they are standing still and everything is rotating around them. From the distance star, they would think they are standing still, and we were rotating super fast like quasars do. How does gravity and time work in this scenario?

The rule that nothing can exceed ##c## applies to inertial frames only. You don't need excessive rotation to cause distant objects to exceed ##c##. Just turn in place. If you can turn a full turn in one second, the nearest star traveled nearly 25ly in one second in your frame. But it will never overtake a light ray, which is the true physical restriction.

So there's nothing particularly special about something spinning in terms of time. You will, of course, be able to detect your rotation with sensitive enough experiments - meteorologists and artillery gunners routinely have to account for Earth's rotation.

PeroK
What will be larger than c is the coordinate speed of light. This is an artefact of a coordinate choice. What cannot exceed the speed of light is the speed relative to other nearby objects.

Demystifier and vanhees71
deedee6905 said:
If the Earth rotates faster, distant stars traveling across the sky would eventually look like they are traveling faster than the speed of light.
That's already true for our actual Earth for stars that are far enough away. But the speed you are thinking of here, as others have already commented, is a coordinate speed in a non-inertial frame, and coordinate speeds in non-inertial frames are not limited to the speed of light.

PeterDonis said:
That's already true for our actual Earth for stars that are far enough away.
In fact, it's true of anything more than ##1/2\pi## light days away, which includes Neptune and Pluto if my arithmetic is reliable.

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Ibix said:
In fact, it's true of anything more than ##1/2\pi## light days away, which includes Neptune and Pluto, if my arithmetic is reliable.
So ... all stars except one. ;)

Ibix said:
In fact, it's true of anything more than ##1/2\pi## light days away, which includes Neptune and Pluto if my arithmetic is reliable.
Orodruin said:
So ... all stars except one. ;)
To be pedantic, only for bodies on the celestial equator. The limit is really$$\frac {1} {2\pi \,\cos \theta}$$light days, where ##\theta## is angle above the celestial equator.

Ibix
DrGreg said:
To be pedantic, only for bodies on the celestial equator. The limit is really$$\frac {1} {2\pi \,\cos \theta}$$light days, where ##\theta## is angle above the celestial equator.
How many stars would we expect to find in the observable universe that fall within the cylinder so defined?

I get in the neighborhood of 80 stars. A cylinder 90 billion light years in length, a cross sectional area of a circle ##\frac{1}{365\ 2\pi}## light years in radius and a stellar density of 0.004 stars per cubic light year.

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Your argument does not rely on magnitude of the rotation. Everything far from the ##\rho## distance of ##\frac{c}{\omega}## in spinning cylindrical coordinate ##\rho, \phi, z##, cannot stop in that rotation system. For an example, 1 light year ##\rho## distance star has speed of ##2\pi/24## light year / hour > c in the Earth spinning frame of reference as we observe in the sky.

I would add to say time in rotational frame of reference share time with IFR clocks. Residents in rotational FR do not own their clocks but use time of "rotating" clocks which are at rest in the IFR where the center of rotation is at rest. This is the reason why 24 hours on the Earth is denominator on the above calculation.
The clocks at rest in rotational FR which cannot be synchronized are inconvenient to use.
The IFR clocks move faster than light speed as well as everything where
$$\rho > c/\omega$$ .

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## 1. What is the theory behind "Time & Gravity in Rotating Faster Than Light?"

The theory behind "Time & Gravity in Rotating Faster Than Light" is based on Einstein's theory of relativity. It suggests that as an object approaches the speed of light, time slows down and gravity increases. This is known as time dilation and is a fundamental principle in understanding the effects of objects moving at high speeds.

## 2. How does time dilation affect the perception of time for an object moving faster than light?

For an object moving faster than light, time dilation causes time to slow down relative to an observer who is not moving at such high speeds. This means that for the object, time will appear to pass slower than for the observer. This effect becomes more pronounced the closer the object gets to the speed of light.

## 3. Can an object actually rotate faster than the speed of light?

According to our current understanding of physics, it is not possible for an object to rotate faster than the speed of light. This is because as an object approaches the speed of light, its mass and energy become infinite, making it impossible for it to reach or exceed the speed of light.

## 4. How does gravity change in a rotating system that is moving faster than light?

In a rotating system that is moving faster than light, the effects of gravity become more pronounced. This is because as an object moves faster, its mass and energy increase, leading to a stronger gravitational pull. Additionally, the rotation of the object can also create gravitational waves, which can further affect the gravitational force.

## 5. What are the potential implications of "Time & Gravity in Rotating Faster Than Light" on our understanding of the universe?

The concept of "Time & Gravity in Rotating Faster Than Light" has potential implications for our understanding of the universe and the laws of physics. It challenges our current understanding of the speed of light as the ultimate speed limit and raises questions about the nature of time and gravity. Further research and experimentation in this area could lead to new discoveries and advancements in our understanding of the universe.

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