31–40 of 61 posts
"Theory for a faster-than-light "warp drive" consistent with general relativity." For real?
http://en.wikipedia.org/wiki/Alcubierre_drive
I honestly can't imagine why NASA even acknowledges the idea of FTL travel - Is there some kind of propeller beanie PAC forcing their hand? They should just have a page that says: "FTL is impossible, but that's fine, once you get used to the way things are."
Earlier quoted context omitted.
I think, definitely not an expert, that when thinking about ways to travel faster than light would not actually involve an object moving through space in the classical sense. You could look instead of at the means (i.e. moving through space) at the goal: Mass first being somewhere, and then being somewhere else in a relatively short amount of time. So the solution would be to cross distance at a low velocity, so you…
Whether or not you drift there or instantaneously teleport there, there are still causality issues. You can make it into your own past by jumping once, changing your speed to tilt the frame of reference you're moving "instantaneously" in, then jumping again. http://casa.colorado.edu/~ajsh/sr/simultaneous.html
But, given the nature of probabilities, if enough trials occurred, eventually one would succeed in causing something to interact with its past self. How would you even detect if that occurs? The particles that have the highest likelihood of doing this by chance all look pretty much the same anyway.
Earlier quoted context omitted.
How do these "legitimate" ideas for FTL deal with causality? I've always wondered that. People always use causality to argue against FTL, but then readily acknowledge that wormholes or Albicurie might allow it. I'm not getting that disconnect?
Here's a link to a good discussion of some related issues by cosmologist Sean Carroll: http://www.preposterousuniverse.com/blog/2011/09/24/can-neut... (It's in the context of that mistaken "neutrinos move faster than light" claim from a few years back, but the arguments are general. Bob Geroch's article mentioned near the end is pretty much the gold standard for dealing with these issues as far as I know.) I really n…
http://exvacuo.free.fr/div/Sciences/Dossiers/Time/A%20E%20Ev...
TL/DR: Yes, the Alcubierre drive does violate causality.
Earlier quoted context omitted.
>They should just have a page that says: "FTL is impossible, but that's fine, once you get used to the way things are." No offense intended to you, but I feel this is a disastrously negative attitude to have. Except where morals dictate otherwise (which are outside the scope of science anyway) nothing is banned from exploration. Suggesting otherwise implies that we know all there is to know about a subject; to me, th…
nothing is banned from exploration Nothing is banned, per se... but there's just too much search space to sift through to not be smart about where you look.
Speaking as a professional physicist, this page feels awfully light on actual information. And as far as I can tell, that's merited: there's not a lot of solid science discussed on this page, or even especially tantalizing ideas for what might come next. They spend a lot of time discussing quantum vacuum energy, but the one short note about its "propulsion implications" includes the comment that "Those particular gra…
That's probably because nobody in the field pays any attention to Haisch, Puthoff, and Rueda, who have been publishing papers on "zero point energy" and how they claim it causes gravity and inertia for a couple of decades now.
Speaking as a professional physicist, this page feels awfully light on actual information. And as far as I can tell, that's merited: there's not a lot of solid science discussed on this page, or even especially tantalizing ideas for what might come next. They spend a lot of time discussing quantum vacuum energy, but the one short note about its "propulsion implications" includes the comment that "Those particular gra…
How do these "legitimate" ideas for FTL deal with causality? I've always wondered that. People always use causality to argue against FTL, but then readily acknowledge that wormholes or Albicurie might allow it. I'm not getting that disconnect?
Wormholes and Alcubierre drives do lead to causality violations. That's why most physicists view them as not physically possible. They're just mathematical solutions to the Einstein Field Equations that can't be physically realized. There are plenty of other such solutions; nobody has ever claimed that every mathematical solution of the equations has to correspond to something that's physically possible.
I honestly can't imagine why NASA even acknowledges the idea of FTL travel - Is there some kind of propeller beanie PAC forcing their hand? They should just have a page that says: "FTL is impossible, but that's fine, once you get used to the way things are."
Scientists, rightly so, are a little leery of stating "we know everything". There's no guarantees our current theories are perfect - in fact, it's extraordinarily unlikely that they are. Also of note: https://en.wikipedia.org/wiki/Alcubierre_drive
Earlier quoted context omitted.
How do these "legitimate" ideas for FTL deal with causality? I've always wondered that. People always use causality to argue against FTL, but then readily acknowledge that wormholes or Albicurie might allow it. I'm not getting that disconnect?
I have a hypothesis, unsupported of course, that everything has a fixed spacetime velocity. As beings with mass, we perceive the universe as having three spatial dimensions and one temporal dimension. We move relatively slowly in the spatial dimensions, and we find it easy to change direction. As a result, we are hurtling incredibly fast in the temporal dimension. A photon, on the other hand, moves incredibly fast in…
Earlier quoted context omitted.
I think, definitely not an expert, that when thinking about ways to travel faster than light would not actually involve an object moving through space in the classical sense. You could look instead of at the means (i.e. moving through space) at the goal: Mass first being somewhere, and then being somewhere else in a relatively short amount of time. So the solution would be to cross distance at a low velocity, so you…
Whether or not you drift there or instantaneously teleport there, there are still causality issues. You can make it into your own past by jumping once, changing your speed to tilt the frame of reference you're moving "instantaneously" in, then jumping again. http://casa.colorado.edu/~ajsh/sr/simultaneous.html