Exploring Faster-Than-Light Travel with a Black Hole

[Toms]

first, I would like to apologize for my lousy english
second,I hardly know anything about relativity (well I understand why you can't travel faster than light, and i understand a few concepts,so I get the simplfied big idea , but I don't know the fine stuff of it)
me and a friend were discussing f.t.l traveling yesterday.
We have read about faster than light traveling by taking a shortcut through space time
now so far evrything I have read is about light that travels in a straight line
but what if light is bended (by the gravity of an extremely dense object, for example, a black hole)?
i made a picture of this

http://img72.imageshack.us/img72/8672/ftltravelispossibleun7.jpg

now thanks to the black hole, the light is not taking a direct way from point B to C
and traveling more distance.
Assume you would counteract the gravitational force of the black hole by igniting side rockets, so you *DO* go in a straight line
faster than light travel mean : basically traveling faster than light, so in this example
is it true that you are traveling faster than light?
or are we horrible wrong here ?

 

[atyy]

In general relativity, it makes sense to say that we cannot travel faster than the speed of light, and also that we can - each meaning something different.

In special relativity, which applies when there is no gravity and space is flat, we can draw space as a horizontal axis and time as a vertical axis. Then the spacetime path of a ray of light will be a straight line with a certain slope. A spacetime path with a slope less than than that of the path of light, represents a particle traveling faster than light, which is forbidden.

When spacetime is curved, only very small parts of space are approximately flat, and within any small region of space, nothing can travel faster than light in the sense defined above.

For large curved regions of space, the above definition no longer holds, and the meaning of the speed of light is ambiguous.

Here is an article describing the different definitions of the speed of light in curved spacetime:
http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/speed_of_light.html

 

[Entropia]

First of all, don't apologize for your English! It's great that you are trying to understand complex concepts and discussing them with your friend.

Regarding faster-than-light (FTL) travel, you are correct that according to Einstein's theory of relativity, nothing can travel faster than the speed of light in a vacuum. This is because as an object approaches the speed of light, its mass increases infinitely and it would require an infinite amount of energy to accelerate it further. So, from a theoretical standpoint, FTL travel is not possible.

However, as you mentioned, there have been some theories proposed about shortcuts through space-time that could potentially allow for FTL travel. One such theory is the concept of wormholes, which are hypothetical tunnels connecting two distant points in space-time. Another idea is the Alcubierre drive, which would involve warping the fabric of space-time around a spacecraft to achieve faster-than-light speeds.

In your example of using a black hole to bend light and potentially travel faster than light, there are a few things to consider. First, the concept of "straight line" becomes tricky when dealing with the curvature of space-time. While the light may appear to be taking a curved path around the black hole, it is actually following a "straight" path in the warped space-time around the black hole.

Secondly, even if you were able to counteract the gravitational force of the black hole and travel in a straight line, you would still not be traveling faster than light. This is because the speed of light is a fundamental constant and cannot be exceeded, regardless of the path or method of travel.

In conclusion, while it is fascinating to explore the possibilities of FTL travel, it is important to remember that it is still just a theoretical concept and has not been proven possible. We must continue to study and understand the laws of physics before we can even begin to consider such possibilities.