Causality

I think there is a flaw in causality and this has a dramatic effect of things that can go faster than light (FTL).

First off, I believe that the distance between two events has a major impact as to how fast things can go without worrying about the cause and effect paradox. Let me explain a little.

Suppose there was a ship that could travel FTL and goes to a nearby star, say 4 light years. From the observation of Earth, the ship speeds up and eventually disappears as the speed increases past the speed of light. Essentially the local photons bouncing off the ship onto the observer on earth are greatly diminished in quantity as it speeds away, eventually going toward zero.

What really would be happening is that the photons coming off the ship still are limited by the speed of light and therefore would come in eventually when they travel the distance form where the ship was at the time of it coming off the ship and then traveling to the observer on earth.

So what happens when the ship arrives at the star. Well, to the observer on the ship, as they approach the destination, more photons will hit the observer and thus will have an increased view of what is happening at the star they are approaching. Basically they will have a fastforward view of the previous 4 years that the star was emitting its light. Most likely distorted by the Doppler effect.

Anyway, when they arrive, they are now slower than the speed of light and hence everything that happens and all the photons that bounce off it will be sent out to the universe as normal.

Now for causality. The observer on Earth will, after 4 years, see (with a sufficiently powerful telescope or measuring device) the events of what happen at the ship's destination star. Because it took that long for the photons to arrive here.

The issue with cause and effect that I say is flawed is that, even if the ship returns before those 4 years back to earth, the cause of those photons at the other star has already happened. It happened to the ship and the crew. So, just because the observers on earth don't actually see what is happening at the star at the time that the crew is doing it (different frame of reference), the effect will be seen when the photons arrive.

If, on the other hand, the ship stays at this new star for 4 years and were observing earth, then they would see their launch from earth. But at some point along this observation it will diminish to near zero while they are watching since the photons that had bounced off during their journey as they approached this new star would have already been seen by the ship 4 years ago. But this time, the approach of the photons as observed by the ship would be in reverse.

The cause and effect would not be changed, just the observation of those effects.

So basically, in a nut shell, the limitations put forth by General Relativity and the universal "speed limit" are merely an observational limitation. You would not see the effect before the cause, i.e. from the perspective of the ship, because the thing that traveled FTL was the cause and thus seeing the reversed "ghost" images of itself once it arrived at the new star are merely the limitation of the photons themselves. In other words, the observation is limited but the cause and the effects are unchanged, just the sequence of observations of the cause.

If the cause was the ship traveling FTL to the new star, then it obviously had to have done it before it arrived at the destination for the observer on the ship to see itself launch.

It's the distance that is traveled that makes this seem paradoxical. What would happen if the ship traveled 1000 light years. Neither the observer on the ship nor the observer on earth would even know, in their lifetime, about the other at all. And thus the cause and effect paradox would not even be an issue.

So things could be zipping around the universe at FTL speeds and we would be none the wiser. How that is achieved is another matter altogether but the need for a better understanding of the "speed limit" needs to be examined.

Perhaps the investigation of the "instantaneous" effect of gravity will help shed light, pun intended, on the matter, more puns. :)