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In books of science fiction (Asimov) I saw the fancy idea of a "jump" over a space-time interval, (i.e. at superluminal velocity and for a VERY SHORT time). The result was landing in another region of the galaxy, that during a human life one has no chance to reach.

Can someone imagine that this fictional idea can become, some day, realistic?

Or, putting in negative form, are we DOOMED to remain exclusively in the neighborhood of our solar system? Given that our Sun is a yellow star (not young) and continuously aging, in a couple of millions of years the life on our solar system will become impossible.

I don't deal with general relativity, s.t. my question is surely naïve. Though, an answer like "light-velocity cannot be surpassed", would be trivial.

DanielSank
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Sofia
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  • We've got a lot longer than couple millions of years. We've got quite a few hundred million years, if not one billion. – HDE 226868 Dec 06 '14 at 01:08
  • This question seems to be a highly speculative, engineering-based, non-mainstream question. – Kyle Kanos Dec 06 '14 at 01:32
  • @KyleKanos: While this may be highly speculative, I hardly think it's "engineering-based". I also fail to see the relevance of whether or not it's mainstream, despite the site's discussion of that word, since the boundaries of what is mainstream are not at all clear. – DanielSank Dec 06 '14 at 01:39
  • @DanielSank: Mainstream physics has a clear definition. Building superluminal spacecrafts seems both engineering-based and non-mainstream to me. I chose primarily opinion based because physics, at this juncture, can't say jack about anything. – Kyle Kanos Dec 06 '14 at 01:46
  • @KyleKanos: According to the definition in the link you posted, this question is easily within the bounds of mainstream physics. I guess we should not argue this any more in the comments, but if you read the definition in your link I think you'll agree. – DanielSank Dec 06 '14 at 01:49
  • @DanielSank are you saying that superluminal travel (for short times) is widely accepted within the physics community? If so, I'd encourage you to make a meta post explaining your reasoning and asking for this question to be reopened. – David Z Dec 06 '14 at 07:33
  • @DavidZ: First of all, I mostly object to the notion that this question is somehow "engineering". As the for the mainsream issue, I could imagine someone discussing on/off shell trajectories, energy/time uncertainty, and why all of that does not mean that you can travel superluminaly. This would seem to me better than just shutting the question down as "off topic", which teaches OP nothing as, as usual, IMHO doesn't even make sense. – DanielSank Dec 06 '14 at 07:50
  • @DavidZ: paraphrasing, the questions are (1) Will superluminal travel ever be possible? and (2) If not, does that mean humans can never venture beyond the solar system? These are perfectly fine questions in the context of mainstream physics. Just because they were inspired by reading sci-fi doesn't make them non-scientific. Also, they aren't mainly about engineering as they are concerned with limitations imposed by physical laws instead of specific implementations. – Christoph Dec 06 '14 at 12:48
  • note that my answer does go the speculative route and is light on physics, but more technical answers about energy conditions, CTCs, some details about time dilation and estimates about interstellar travel with relativitic rockets are possible... – Christoph Dec 06 '14 at 12:58
  • Related: http://physics.stackexchange.com/q/2166/2451 , http://physics.stackexchange.com/q/147344/2451 , and links therein. – Qmechanic Dec 06 '14 at 13:58

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In principle, general relativity allows space-time to have non-trivial topology (wormholes) or dynamics (Alcubierre drive) that could be used to 'cheat'. However, it is very likely that such things do not exist (they violate some 'reasonable' assumptions about the universe, but without a predictive theory of quantum gravity, no one can say for sure); but even if they did, it is doubtful that they could be used for travel.

So no, we're stuck with the universal speed limit $c$. However, thanks to time dilation, that's not as much of a problem as one might think - you just cannot do real-time communications or round trips (more precisely: you'd 'time-travel' to the future - the well-known twin paradox).

Logistics would be a real problem if you ever wanted to establish a galactic civilization, but imo it is a great opportunity for 'hard' sci-fi.

As long as we're speculating, I can think of 3 different approaches for interstellar travel and colonization:

  • small relativistic rockets, possibly aided by cryonics (which might also help to avoid negative effects of radiation); such ships need heavy shielding at the bow
  • big generational ships, possibly using solar sails (seems that's not realistic for big payloads?), possibly using a big shell made of water and ice as shielding
  • not sending humans at all and going the AI route, possibly using self-replicating robotic ships
Christoph
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