Faster than light travel

[Morrus]

It's very cool that this thread involves people talking about stuff that the rest of us don't understand -- and I don't mean that sarcastically, I heartily approve! I love that this place can host that sort of conversation, even if it's beyond me personally!

 

[Umbran]

That's true for light originating at the event horizon. Light originating within the event horizon follows a path that reaches the singularity at the center of the black hole. Any direction in which light can be emitted within a black hole points towards the singularity.

I'm aware.

Sorry, I do more editing of my comments for a broader audience than some of the rest of you, and that was a level of complexity I didn't think relevant for this discussion.

 

[Umbran]

Except that special relativity allows you to change things by merely changing your velocity. If there are 2 events outside each other's light cone, the order in which they happen can be changed by changing your velocity. The past is not fixed; it depends on your point of view.

But, again - sub-light, there are places you CANNOT get to. If they are outside your light cone when you start, there is NO WAY to ever get there.

Some of the reading I've done on the Alcubierre drive suggests that it may have similar, but far more complicated, aspects. There may be regions of spacetime that it cannot reach, such that the closed curve is impossible.

Whether it is true? Moot, until they bring the energy requirements down by 30 orders of magnitude or so. That's unlikely to happen in any of our lifetimes, so I am happy to toy with the possibility. If you aren't happy to do so... that's your choice.

 

[Ryujin]

Really, REALLY hoping that this is all moot and that "The Road Not Taken" is accurate, with respect to faster than light travel.

The Road Not Taken (short story) - Wikipedia

en.wikipedia.org

 

[shawnhcorey]

But, again - sub-light, there are places you CANNOT get to. If they are outside your light cone when you start, there is NO WAY to ever get there.

There is no way to get there without FTL travel. But with FTL travel, even the far past is accessible.

 

[tomBitonti]

I'm aware.

Sorry, I do more editing of my comments for a broader audience than some of the rest of you, and that was a level of complexity I didn't think relevant for this discussion.

Sure, but this is important to understanding how things work inside a black hole. There are a lot of misconceptions that are cleared up knowing that all movement within a black hole at less than or equal to the speed of light points to the center of the black hole.
Thanks,
TomB

 

[Umbran]

Sure, but this is important to understanding how things work inside a black hole.

Except, of course, it isn't. For the majority of readers here, it is a curiosity, and nothing more. It doesn't even fit into the science literacy needed to make reasonable decisions for day-to-day life in a technological culture.

There is a strong argument that since by definition these things cannot be observed, they fall into the pile of "non-falsifiable" items that aren't even science, per se.

 

[tomBitonti]

Except, of course, it isn't. For the majority of readers here, it is a curiosity, and nothing more. It doesn't even fit into the science literacy needed to make reasonable decisions for day-to-day life in a technological culture.
There is a strong argument that since by definition these things cannot be observed, they fall into the pile of "non-falsifiable" items that aren't even science, per se.

Well sure. What can be said about the interior of a black hole is arguably philosophy, not physics. One simple alternative view of black holes is that they have no interior. No currently conceivable experiment can measure anything about the interior. The point is important for anyone wanting to deepen their understanding of things. Special relativity is a subject that extends beyond black holes. But the real problem is that the statement is quite misleading. I don't think it should be provided even casually, as it leads folks to incorrect thinking. For example, it seems to allow a chain of in-falling devices, each with an emitter and a receiver, relaying signals outwards, while removing the incremental red-shift of the prior device.
Thanks!
TomB

 

[GreyLord]

Well sure. What can be said about the interior of a black hole is arguably philosophy, not physics. One simple alternative view of black holes is that they have no interior. No currently conceivable experiment can measure anything about the interior. The point is important for anyone wanting to deepen their understanding of things. Special relativity is a subject that extends beyond black holes. But the real problem is that the statement is quite misleading. I don't think it should be provided even casually, as it leads folks to incorrect thinking. For example, it seems to allow a chain of in-falling devices, each with an emitter and a receiver, relaying signals outwards, while removing the incremental red-shift of the prior device.
Thanks!
TomB

Isn't Physics...pure physics...mostly a math driven thing? Thus, there are things that they can't even observe but which they can see the math predict which are theories.

In such a way, couldn't the math be part of the evidence regarding the interior of a black hole or special relativity?

 

[shawnhcorey]

In such a way, couldn't the math be part of the evidence regarding the interior of a black hole or special relativity?

You can prove anything with math; it all depends on your assumptions. Nobody knows what the interior of a black hole is like, so the assumptions run wild. I read one article where gravity was reversed inside the event horizon. Everything was pushed out to the event horizon. The math was good but the assumptions were debatable.