Barring significant new physics, nothing can travel faster than the speed of light. And that's really a very probably no - although you see popular science stuff written like it can solve the problem, it doesn't, and we have no real expectation that anything will.

Dark matter, if it is matter (and there are good but not totally confirmed reasons to think it is) is just that...matter. It would really be not that special at all, except that it doesn't interact electromagnetically, but this doesn't particularly have deep implications - we already know about particles like that, neutrinos, but they happen to be lighter than the ones that would make up dark matter.

Given that we know very little about gravity and other effects that distort space-time, it's conceivable that faster than light travel may be possible without violating the relativity limit, by distorting space. We don't think that it is possible without producing the ability to travel back in time -- which is considered impossible --, but we also know very little about the subject.

We're nowhere near it, but clearly at the stage of: we know that we know next to nothing about it. Just have a look at the discussion around the Alcubierre Drive and you'll get the feeling that it is pie-in-the-sky science.

So, I'd wager it's not a "very probably no". It's a "we have no clue".

I've heard of the possibility of "apparent" FTL through worm holes or other disturbances in spacetime, what do you think of those

There are lots of interesting questions about what this would really mean, but it wouldn't break the FTL barrier - it's really taking a shorter path, not taking a long path but going faster.

This potentially raises paradoxes etc, and may also be impossible, but it doesn't break the barrier in the above sense.

Well, other than space itself, hence the whole inflation idea when the whole universe expanded faster than the speed of light.

The universe initially expanded very quickly but not at the speed of light.

A university professor of mine[0] who was (perhaps still is) involved directly in international scientific efforts to examine the expansion of the universe once explained the speed of expansion of the universe to me in a way that made perfect sense.

Unfortunately I can't remember the precise details but the concept relates to a change in scale of the distance between bodies.

My best approximation is this: the measurable distance between two points can increase without either point moving if the nature of what is between the points changes.

You can pseudo-simulate the concept as follows:

1. Open Google maps at a reasonable "normal" scale

2. Affix two dots to your screen and take a guess as to the distance between them as if the dots were actually on the map

3. Zoom out the map quickly as far as it will go

4. Guess again the distance between the dots

The ground distance between the dots increases dramatically. One could argue that the dots moved apart at a great speed, possibly greater than the speed of light if the change in distance is sufficient.

Clearly we know that the dots did not move. The scale of what was between them moved.

During the initial stages of the universe things behaved very oddly.

[0] http://www.brunel.ac.uk/cedps/electronic-computer-engineerin...

There is a very interesting concept that indicates that the limit of speed is not light, but the space itself. Space itself is such that it cannot let anything travel faster than light. It's like check points in space which slows down light to it's speed we call C.

May be somewhere in the universe, or within the black hole, space is malleable enough to allow faster than light travel. It's just a concept, but a very interesting one.

Wanna know the real reason? C is just the maximum floating point value of the computer that our universe's simulation is running on. Similarly, the Planck length is the value closest to zero.

I reasoned about it in the same vein but with a different approach. We are running in a discrete simulation. The most you can move is one space quantum per time tick. That speed is C.

More likely, it is the maximum speed the physics engine can handle per tick.

That's exactly my point. If the speed (= distance / tick) is represented by a float, then we can travel no faster than the max float value.

"3 x 10^8 m/s ought to be enough for anybody"

That would perhaps be even more interesting!

That's beautifully put :)

I recall fragments of a theory that everything moves at the same speed (think multidimensional unit vector), just in various directions (time included as a "direction", explaining why if you travel C in one physical direction "your" time stops).

Perhaps someone can point me to a full description of this theory.

I just like to think of it at the universe's loading screen.

You couldn't travel in 3 dimensional space faster than the speed of light, but you can travel vast distances faster by taking "short cuts" through other dimensions.

I'm guessing the author used 'C space' as a way of describing '3 dimensional' (ie a = 1, b = 2, c = 3). So 'C space beings' would be limited to light speed travel (unless we build meat containers that could manipulate or penetrate 'D space')

I'm assumed that it's called C space because the speed of light is normally termed c - so the space was described in terms of the limiting speed.

wouldn't that break causality ? because light / information would still travel in 'C space'.

Not really. Sound travels faster than light so we see really fast moving objects before we hear them. If we folded the universe and took a shortcut then we'd just arrive at the destination before it's visible that we've left. But that's little different to seeing stars millions of light years away shining away which would have already died thousands of years ago (hence why some scientists romanticize about astronomy as being like time travel - as they're often looking at events that happened hundreds or even millions of years in the past)

In any case, there's already enough literature on this subject to last you a life time so if you have any question then it's an interesting subject to read. And by "literature" I don't mean "Star Trek" (though their "Warp Drives" are based on a similar premise or warping 3 dimensional space - despite obviously being a work of fiction)

Yes. Of course the only evidence we have for causality is that we have not observed it being broken (and recognized that observation)

Random thought: if, as we're concluding, it's information that cannot travel FTL, maybe "dark matter" is matter which information cannot adhere to (completely fungible: you absolutely cannot discern the difference between one piece and another), allowing FTL movement because you can't discern "it was here, and now it's there, so d/t > c" because you can't differentiate "it" from another "it".

Seems the emerging refinement is that information cannot travel faster than C. (Ergo "digital life" can't move FTL.) If anything can more FTL, the information associated cannot keep up, and the notion of "it" breaks down as what you know about "it" can't keep up with where "it" is.