The visual effects of Faster-Than-Light (Superluminal) Travel

The visual effects of Faster-Than-Light (Superluminal) Travel are difficult to explain intuitively. Most people just ignore it.

I set up an animated gif to demonstrate how it might appear.

For those of you that might care about obscure Federation Lore and errata, this is the basis of the Picard Maneuver. You will be able to see how it would actually work.

This was based on a throw-away line Neil deGrasse Tyson said once at a conference about what would FTL look to an outside observer. It stuck with me for years. I am still looking for the original reference.

In this example, a spaceship takes off from the surface of the green planet and lands on a red planet which is slightly less than 1 AU (Astronomical Unit) away. 1 Astronomical Unit is 499 light seconds. In this example, it is 8 light minutes away. The white lines on the diagram are each 1 light minute.

At the beginning, the red observer and the blue astronaut look at the red planet. What they are seeing is what the red planet looked like 8 minutes ago.

The spaceship is travelling at a modest (modest for sci-fi) speed of 8 times the speed of light. It actually arrives at the red planet in 1 minute.

The red observer on the ground watches the blue astronaut take off in the FTL ship.

15 seconds after the blue person took off in the FTL ship, they are already 2 light minutes away from the green planet. It will take 2 minutes and 15 seconds AFTER the blue astronaut took off the the red person will see where they were 15 seconds after they took off.

1 minutes after take off, the blue astronaut's ship arrives on the red planet. It will not be until 9 minutes after take off will the red person see this.

Immediately the blue astronaut takes off and heads back to the green planet.

At the 2 minute mark, the Blue Astronaut is back on the green planet and watches their own ship.

By the time the blue astronaut is return, the Blue Astronaut and the Red Observer see that the Blue Astronaut's ship only appears to be 1.85 light minutes away.

The Blue Astronaut and the Red Observer also watch the FTL ship fly back from the green planet to the red planet and arrive at about the same time as they originally took off.

The red observer sees the return of the Blue Astronaut and their ship, but only see it arrive in reverse AFTER the blue astronaut arrived back on the green planet.

From the 2 minute mark onwards until the 9 minute mark, there will appear to be 3 space ships, then abruptly at the 9 minute mark, there will only be the final spaceship on the green planet.

The net result is that the blue astronaut travelled back in time 7 minutes.

If supeluminal travel were common, there would be no causal relationship between what is seen and what is actually occurring.

Superluminal travel which do not pass thru normal space do not have this acausality. The Superluminal Travel is still time travel but do not cause the visual paradox. They are still subject to Visser effects from retrocausality. retranscription.

In the relatively dense gravity well of a solar system, the energy density of the visser effects would destroy the attempted time traveller. In the ultra-vacuum and flatapace of the interstellar medium, the Visser effects would be minimal.

There are methods of superluminal travel that do not have such Visser effects, like fixed location stargates and fixed location traversible wormholes because the Visser effects were taken care of during the process of their construction.