Faster than light travel

[Umbran]

Also, black holes are not the final word on super-massive objects. An better theory is magnetospheric eternally collapsing object (MECO).

Lots of people have issues with the idea of singularities, and for nearly a century now, there's been folks looking for arguments that they are not possible. MECOs are another in the long series.

In the end, the only clear measure of "better" is fitting the observational data more cleanly, which the MECO model does not, as yet, do. Beyond that all distinctions of "better" or "worse" are matters of human aesthetics, not science.

 

[Morrus]

Also, black holes are not the final word on super-massive objects. An better theory is magnetospheric eternally collapsing object (MECO).

What makes it better?

 

[Umbran]

First of all, all FLT travel is time travel.

This may not be exactly true. Einsteinian closed timelike curves are, yes. However, the Alcubierre drive may not be. The wall of the "warp bubble" is a barrier between the interior and the rest of spacetime that prevents those inside from having causal connection with the rest of the universe. This may prevent the people inside from following a closed timelike curve - it rather depends on what slowing down and opening the bubble looks like.

 

[shawnhcorey]

What makes it better?

Gravity travels at the speed of light. Yes, it's been measured. So if light cannot escape a black hole, how can gravity? With a MECO, there is no event horizon and so, it still has gravity.

 

[Morrus]

So if light cannot escape a black hole, how can gravity?

You’re saying gravity is slowed by gravity?

 

[shawnhcorey]

This may not be exactly true. Einsteinian closed timelike curves are, yes. However, the Alcubierre drive may not be. The wall of the "warp bubble" is a barrier between the interior and the rest of spacetime that prevents those inside from having causal connection with the rest of the universe. This may prevent the people inside from following a closed timelike curve - it rather depends on what slowing down and opening the bubble looks like.

This is a common misconception. It does not matter how FTL travel is done. All that matters is that there are 2 events outside of each other's light cone. And the events are starting FTL travel and ending it.

The only way to do FTL travel without time travel is to have a preferred frame of reference. But since both special relativity and general relativity assume there is no preferred frame of reference, having one would invalidate them.

 

[Umbran]

You’re saying gravity is slowed by gravity?

Not any more than gravity slows down light - which is to say not at all. Things with zero mass (photons and gravitons) move at a fixed speed in vacuum. Rather than slowing down, they lose energy - meaning the their wavelengths get red-shifted. Saying "light cannot escape a black hole" is saying that light originating within the black hole gets red-shifted to nothing.

 

[shawnhcorey]

You’re saying gravity is slowed by gravity?

Is light slowed by gravity? No. The supposition that is given is that gravity expands the radial distance. For a black hole, it is expanded to infinite. Since everything travels at the speed of light or slower, nothing can escape a black hole.

 

[Morrus]

Is light slowed by gravity? No. The supposition that is given is that gravity expands the radial distance. For a black hole, it is expanded to infinite. Since everything travels at the speed of light or slower, nothing can escape a black hole.

My brain is just kinda hurting by the concept that something which causes gravity is the very thing that prevents gravity escaping it. I get stuck in this circular self-referential loop, which basically means I don't understand it.

 

[Umbran]

This is a common misconception. It does not matter how FTL travel is done. All that matters is that there are 2 events outside of each other's light cone. And the events are starting FTL travel and ending it.

Again, the warp bubble complicates this. It takes the interior of the bubble outside everybody's light cone - things inside are causally disconnected from the rest of the universe while it exists. If the event that is "staring" effectively happens inside, there's no violation.

There are some other aspects of the Alcubierre drive that may limit where one goes at what speeds, which may prevent a closed timelike curve from forming. Basically, you may be able to take such a drive from point A to point B faster than light, but it may be that you could not return to your starting point (at least, not any sooner than light would make the round trip) - so the curve cannot be closed.