# Information traveling faster than light

• B
• MiLara
In summary, the gears proposal would be limited in the same way that the rod would be. It would be noticeable that the time delay between actions was there, but it might just barely be detectable.
MiLara
I know there is a modern paradigm that states that nothing, including information, can travel faster than the speed of light. (With exception to quantum entanglement, but I'm not going to pretend like I know the exact details of that subject).

Thought experiment.

Imagine there are a series of gears in a row that span a much greater length than 3*10^8 meters. Now let's say you turn the gear at the beginning and it sets off a reaction to the other gears down line from the beginning. Could the last gear turn "instantaneously" or much under 1 second after the first gear is turned? Would this then be considered information being conveyed at faster than the speed of light? What are the limitations of such a device, and how much would friction or any other factors play a roll in the time delay from the first gear turning to the last.

Now let's imagine a really long pole that is much longer that 3*10^8 meters. If you were to all of a sudden push that pole perfectly straight forward from one end, it seems like the other end would move at that exact moment because it is a rigid body. Would this be considered sending information faster than the speed of light, or even sending information instantaneously?

Now, I'm sure I'm not clever enough to have created such an simple device that seems to defy the laws of physics, and to that end, I'd love for someone to tell me what I am missing.

Actions taken at one end of your gears or the pole travel at the speed of sound through the material, which is much slower than c.

Stephanus and MiLara
MiLara said:
Now let's imagine a really long pole that is much longer that 3*10^8 meters. If you were to all of a sudden push that pole perfectly straight forward from one end, it seems like the other end would move at that exact moment because it is a rigid body. Would this be considered sending information faster than the speed of light, or even sending information instantaneously?
This is a pretty commonly asked question. Here is a good reference that discusses it

https://www.physicsforums.com/insights/can-i-send-a-signal-faster-than-light-by-pushing-a-rigid-rod/

The gears proposal would also be limited in the same way.

MiLara and Drakkith
MiLara said:
Thank you! That was very helpful. Now I wonder how long an object would have to be in order for the time delay to be noticed by human eyes.
Hmm, good question. Since movies play at like 22 or so frames per second, I would say that you could probably detect something at 100 ms for sure. The speed of sound in steel is about 6000 m/s, so you should be able to see it in a 600 m length.

Stephanus and stoomart
MiLara said:
Now I wonder how long an object would have to be in order for the time delay to be noticed by human eyes.
The speed of sound in solid steel is somewhere around 6 kilometers/second, and the human eye can distinguish events separated by maybe a tenth of a second... So you might think that under ideal conditions an alert person might just barely be able to perceive the time lag between pushing one end of a 600 meter steel rod and the other end moving.

There's no relativity involved here, this is just about steel not being perfectly rigid. On the one hand, six km/sec is about one five-thousandth the speed of light, far too small for any relativistic effects to appear. On the other hand, the non-rigidity of a 600 meter steel rod is going to be very apparent; it will behave more like a steel cable, all stretchy and flexible, than a rigid bar.

[edit: Dale beat me to it!]

Stephanus, Dale and stoomart
Nugatory said:
the non-rigidity of a 600 meter steel rod is going to be very apparent; it will behave more like a steel cable, all stretchy and flexible, than a rigid bar.

Like these, for example...

Stephanus

## 1. Can information really travel faster than light?

According to our current understanding of physics, no, it is not possible for information to travel faster than the speed of light. The speed of light is considered to be the maximum speed at which any kind of information or energy can travel in the universe.

## 2. What about quantum entanglement? Doesn't that allow for faster-than-light communication?

While quantum entanglement does involve instantaneous communication between two particles, it does not actually transfer any information. The properties of the particles are already determined before they become entangled, so no new information is being transmitted faster than light.

## 3. What would happen if information could travel faster than light?

If information could travel faster than light, it would violate the principle of causality, which states that an effect cannot occur before its cause. This could lead to paradoxes and inconsistencies in our understanding of the universe.

## 4. Are there any exceptions to the speed of light limit?

One exception is the expansion of the universe, which can cause objects to appear to be moving away from us faster than the speed of light. However, this is due to the expansion of space itself, not the actual movement of the objects.

## 5. Is there any ongoing research or theories that could potentially allow for information to travel faster than light?

Some theories, such as wormholes or the Alcubierre drive, propose ways in which information could travel faster than light. However, these are still theoretical and have not been proven to be possible or practical. Further research and experimentation are needed to fully understand the possibilities of faster-than-light travel.

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