That ‘directional radio signal’ is taking a longer path, as noted by the fact that a different directional radio signal (one that went with the traveler) would get there first.
Are you using a Euclidean definition of speed? Part of the insanity is that the payload, inside the bubble, can be at rest relative to the origin and/or destination, despite the distance changing.
Sanity check: before, during, and after the trip, shine a laser continuously ‘forward’, toward the destination. Turn off the bubble well short of arrivial. What pattern of red shifting should the destination expect to see?
Part of the insanity is that the payload, inside the bubble, can be at rest relative to the origin and/or destination, despite the distance changing.
I’m sure it only looks like insanity to people who haven’t studied general relativity.
The point is that an Alcubierre drive lets you get from here to Alpha Centauri (which I now discover is actually 4.4 light years away, since I finally decided to look it up just then) in less than 4.4 years. Whether it does that by temporarily making the distance shorter along a certain path is mostly irrelevant for the purpose of classifying it as a particular kind of starship drive.
The point which started the discussion is that you don’t get to look back and see yourself leave. (probably; I’m not certain how light behaves when there is more than one ‘straight line’ path, of different lengths, to the destination; that seems like is could happen if you took a dogleg around the most direct path.
That ‘directional radio signal’ is taking a longer path, as noted by the fact that a different directional radio signal (one that went with the traveler) would get there first.
Are you using a Euclidean definition of speed? Part of the insanity is that the payload, inside the bubble, can be at rest relative to the origin and/or destination, despite the distance changing.
Sanity check: before, during, and after the trip, shine a laser continuously ‘forward’, toward the destination. Turn off the bubble well short of arrivial. What pattern of red shifting should the destination expect to see?
I’m sure it only looks like insanity to people who haven’t studied general relativity.
The point is that an Alcubierre drive lets you get from here to Alpha Centauri (which I now discover is actually 4.4 light years away, since I finally decided to look it up just then) in less than 4.4 years. Whether it does that by temporarily making the distance shorter along a certain path is mostly irrelevant for the purpose of classifying it as a particular kind of starship drive.
The point which started the discussion is that you don’t get to look back and see yourself leave. (probably; I’m not certain how light behaves when there is more than one ‘straight line’ path, of different lengths, to the destination; that seems like is could happen if you took a dogleg around the most direct path.