Okay people. Here it is. Faster Than Light propulsion theories. Ideas? Questions? Answers?


Here are some of the theories I found on Wikipedia. Enjoy.

<b>Option A: Ignore special relativity</b>

This is the simplest solution, and is particularly popular in science fiction. However, empirical evidence unanimously support Einstein's theory of special relativity as the correct description of high-speed motion, which reduces in the low-speed case to Galilean relativity, which is an approximation only valid for slow speeds. Similarly, general relativity is unanimously supported as the correct theory of gravitation in the regime of very large masses and long distances. Unfortunately, general relativity breaks down at small distances and is no longer valid in the quantum regime. Special relativity is easily incorporated into nongravitational quantum field theories, however it only applies to a flat Minkowski universe.[citation needed] In particular our expanding universe contains stress-energy which curves the ambient space time and perhaps even has a cosmological constant and so is not Minkowski and in particular is not invariant under Poincaré transformations. However even in the broader context of general relativity, acceleration from subluminal to superluminal speeds does not appear to be possible.



<b>Option B: Get light to go faster (Casimir vacuum)</b>

Einstein's equations of special relativity posit that the speed of light is invariant in inertial frames. That is, it will be the same from any frame of reference moving at a constant speed. The equations do not specify any particular value for the speed of the light itself. That is an experimentally determined quantity, though it has an exact value because the units of length are defined using the speed of light.

The experimental determination has been made in vacuum. However the vacuum we know is not the only possible vacuum which can exist. The vacuum has energy associated with it, called the vacuum energy. This vacuum energy can be changed in certain cases. When vacuum energy is lowered, light itself can go faster than the standard value 'c'. Such a vacuum can be produced by bringing two perfectly smooth metal plates together at near atomic diameter spacing. It is called a Casimir vacuum. Calculations imply light will go faster in such a vacuum.[citation needed] However, there has been no experimental verification, since the technology to detect the change isn't yet available.

Einstein's equations of special relativity have an implicit assumption of homogeneity. Space is assumed to be the same everywhere. In the case of the Casimir vacuum, this assumption is clearly violated. Inside the Casimir vacuum, we have homogeneous space, and outside it, we have homogeneous space as well. Inside the Casimir vacuum, the equations of special relativity will apply with the increased value of the speed of light. Outside it, the equations of special relativity will apply with the normal 'c'. However, when considering two frames of reference, one inside the vacuum, and one outside, the equations of special relativity can no longer be applied, since the assumption of homogeneity has been broken. In other words, the Casimir effect breaks up space into distinct homogeneous regions, each of which obey the special relativity laws separately.

While this may technically qualify as 'faster-than-light', that is only true relative to two disconnected regions of space. It is unclear whether (and unlikely that) a Casimir vacuum is stable under quantum mechanics, and whether non-trivial communication is possible between two such regions.

While getting light to go faster still doesn't mean you can travel faster then it, it just ups the speed limit from the standard one of 299,792,458 m/s, which would be useful.



<b>Option C: Give up causality</b>

Another approach is to accept special relativity, but to posit that mechanisms allowed by general relativity (e.g., wormholes) will allow traveling between two points without going through the intervening space. While this gets around the infinite acceleration problem, it still would lead to closed timelike curves (i.e., time travel) and causality violations.[citation needed] Causality is not required by special or general relativity, but is nonetheless considered a basic property of the universe that should not be abandoned. Because of this, most physicists expect (or perhaps hope) that quantum gravity effects will preclude this option[citation needed]. An alternative is to conjecture that, while time travel is possible, it never leads to paradoxes; this is the Novikov self-consistency principle.



<b>Option D: Give up (absolute) relativity</b>

Due to the strong empirical support for special relativity, any modifications to it must necessarily be quite subtle and difficult to measure. The most well-known attempt is doubly-special relativity, which posits that the Planck length is also the same in all reference frames, and is associated with the work of Giovanni Amelino-Camelia and João Magueijo. One consequence of this theory is a variable speed of light, where photon speed would vary with energy, and some zero-mass particles might possibly travel faster than c. While recent evidence casts doubt on this theory, some physicists still consider it viable.[citation needed] However, even if this theory is true, it is still very unclear that it would allow information to be communicated, and appears not in any case to allow massive particles to exceed c.

There are speculative theories that claim inertia is produced by the combined mass of the universe (e.g., Mach's principle), which implies that the rest frame of the universe might be preferred by conventional measurements of natural law. If confirmed, this would imply special relativity is an approximation to a more general theory, but since the relevant comparison would (by definition) be outside the observable universe, it is difficult to imagine (much less construct) experiments to test this hypothesis.



<b>Option E: Go somewhere where the speed of light is not the limit</b>

A very popular option taken in science fiction novels, movies, television programs, and computer games is to assume the existence of some other realm (typically called hyperspace or subspace) which is accessible from this universe, in which the laws of relativity are usually distorted, bent, or nonexistent, facilitating rapid transport between distant points in this universe, sometimes with acceleration differences - that is, not requiring as much energy or thrust to go faster. To accomplish rapid transport between points in hyperspace/subspace, special relativity is often assumed not to apply in this other realm, or that the speed of light is higher. Another solution is to posit that distant points in the mundane universe correspond to points that are close together in hyperspace.

This method of faster-than-light travel does not correspond to anything seriously proposed by mainstream science, although there are also no arguments precluding its existence.



<b>Option F: Become faster without acceleration</b>

An often-implicit assumption about getting something past light speed is that one must get it to light speed as an intermediate step, thus encountering the infinite energy problem. Similar to the idea of using wormholes to instantly change location, there might be a method to instantly change velocity, rather than having to accelerate through all intermediate velocities. The energy required for acceleration hits an asymptote as one approaches light speed. Thus, an object going much faster than light speed might only need energy comparable to an object going much slower than light; the difficulty lies in figuring out how to "convince" particles to move faster than light without resorting to acceleration. (This also gets around the problem of including a human being; inertia is related to acceleration, not velocity, so it would not occur.)

As of yet, no method is known of instantly changing the velocity of matter.




<b>Option G: Consider speed as a complex quantity</b>

A plot device put forth by science fiction author Catherine Asaro, arises from plugging in faster-than-light speeds into the equations of special relativity, to determine what conditions are necessary for faster-than-light speeds to happen. According to her, this is possible when speed has an imaginary component as well as a real one. See Inversion Drive.




<b>Option H: SpaceTime Fabric</b>

Although the theory of special relativity forbids objects to have a relative velocity greater than light speed, and general relativity reduces to special relativity in a local sense (in small regions of spacetime where curvature is negligible), general relativity does allow the space between distant objects to expand in such a way that they have a "recession velocity" which exceeds the speed of light, and it is thought that galaxies which are at a distance of more than about 14 billion light years from us today have a recession velocity which is faster than light.[1] Miguel Alcubierre theorized that it would be possible to create what is called an Alcubierre drive in which a ship would be enclosed in a "warp bubble" where the space at the front of the bubble is rapidly contracting and the space at the back is rapidly expanding, with the result that the bubble can reach a distant destination much faster than a light beam moving outside the bubble(journal paper). Such warping would require a source of negative energy which would act as anti-gravity.

gush i love the "ignore special relativity" ... that settles the nature of the post.

Yeah that one didn't really make much sense to me. But I just threw them on there so people had more to discuss, incase there were some on here who didn't know too much about the topic.

The idea is that science fiction is just that - science fiction. One can, in order for plot, assuming that -something- happened to disregard physical laws. It is a plot device to move things along, make them more interesting. Accordingly, special relativity isn't so hard and fast.

Yeah I thought it might suit the scifi area, but it doesn't seem to be very interesting to anyone(new user alert, sorry. =D). I'll probably ask that moderator person to delete it.

Yeah I thought it might suit the scifi area, but it doesn't seem to be very interesting to anyone(new user alert, sorry. =D). I'll probably ask that moderator person to delete it.

No.

Want people to reply to ur threads? Want to be in center of conversation?

Make it all facts...describe briefly what FTL propulsion is...get a picture...

only use 10 medium sentences for intro post. And thatll snap some interest to you.

Erm......I'm not really looking to be in the spot light. I was just curious to see if anyone had anything to say about it. You'll have to excuse my ignorance about the methods of posting, as most of this is new to me.

Erm......I'm not really looking to be in the spot light. I was just curious to see if anyone had anything to say about it. You'll have to excuse my ignorance about the methods of posting, as most of this is new to me.

(curious to see if anyone had anything to say about it) = (looking to be in the spot light)

:) :D

That's quite a presumption. So if you propose an idea, no matter the idea, and are simply looking for opinions, without sending thousands of private messages, you would be looking to be in the center of attention?

I don't agree at all.

That's quite a presumption. So if you propose an idea, no matter the idea, and are simply looking for opinions, without sending thousands of private messages, you would be looking to be in the center of attention?

I don't agree at all.

well ok in some sort of attention...maybe not center...maybe corner attention...:)

I'd still be inclined to disagree, simply because I'm a behind the scenes kind of guy, and I keep an open mind and value opinions of others. But...........I do enjoy my corners. =D

I liked the first post very much. It is a good idea to cover all the bases.One section caught my eye-
<b>Option C: Give up causality</b>

Another approach is to accept special relativity, but to posit that mechanisms allowed by general relativity (e.g., wormholes) will allow traveling between two points without going through the intervening space. While this gets around the infinite acceleration problem, it still would lead to closed timelike curves (i.e., time travel) and causality violations. Causality is not required by special or general relativity, but is nonetheless considered a basic property of the universe that should not be abandoned. Because of this, most physicists expect (or perhaps hope) that quantum gravity effects will preclude this option. An alternative is to conjecture that, while time travel is possible, it never leads to paradoxes; this is the Novikov self-consistency principle.
Apart from the Novikov solution, there is the possibility that simple geometry might solve the problem of causality. Perhaps the only wormholes which will be traversable will be the ones which do not create closed time-like curves; other holes might be closed by Cauchy horizons or a flood of virtual particles as suggested by Matt Visser.
See this page for a suggestion as to how that would work
http://www.orionsarm.com/whitepapers/wormholes_and_causality.html

I find it very suspect that nature would allow going back in time in theory, yet not in practice. Rather, I imagine time is impossible to travel back through.

I disagree I think back is the only way to go. Because you don't really have to travel anywhere all you need is a telescope and a distant light source. But hey who knows what we will be able to do in 50,100, or 200 years from now. what ever it is I wish I could see it.

I believed that some scientist were able to move "something" fasther then light the only problem was that it didn't carry information, so we will problably be able to surf FTL in no time
http://www.scienceblog.com/light.html
sorry couldn't find a better link for it, it's been a couple of years actually. Does annybody know in witch category this would fit from the first post?

Light can be sped up relatively past C, but we won't be able to take advantage of it to do anything at all with it.

Chances are we'll never go faster than light.

Light can be sped up relatively past C, but we won't be able to take advantage of it to do anything at all with it.

Chances are we'll never go faster than light.

past C? or past c? E=(m)(c^2)

Past celeritas.

realtivley spoken you may be right I don't believe we would ever build a ship that will thrust infinite energy for a infinite time without sending it in a bllack hole or something.
However keep in mind that evrything in the universe can be dublicated, and if wormholes are wreal, then ithrust might be comparising Daedalus with a modern aircraft

Does anybody know in witch category this would fit from the first post?Unfortunately none of them. All that is achieved in most experiments which speed up light waves to faster than light speed is an acceleration of the Group Velocity; the waves are superimposed upon one another in an ingenious way which makes the wave forms travel faster than light speed, while the photons themselves actually continue to travel at exactly the speed of light. Using this method can never convey information faster than light, unfortunately.

The idea which comes closest is the idea of speeding up light by changing the medium through which it travels; between two very close plates the Casimir effect comes into play, and it is possible that the speed of light is faster in that tiny region; exactly how that would work in practice I don't know, as you could hardly build a pair of plates which stretched all the way to Alpha Centauri now, could you?

Unfortunately none of them. All that is achieved in most experiments which speed up light waves to faster than light speed is an acceleration of the Group Velocity; the waves are superimposed upon one another in an ingenious way which makes the wave forms travel faster than light speed, while the photons themselves actually continue to travel at exactly the speed of light. Using this method can never convey information faster than light, unfortunately.
I'm afraid this is above my limit of knowledge of FTL how can you detect something and not carry information on it?

building your plates from one star to a other might indeed be a little bid silly (in the same way a space elevator is).

It's the one thing that violates the cardinal rule of sci fi, which is that all the science has to be realistic. As someone pointed out to me in a thread a while ago, perhaps this is science fiction's bit of magic realism. The story is precisely about what life would be like if that one thing about the universe--the impossibility of FTL travel--were different from our reality. That is indeed the essence of magic realism. Write it in Spanish about levitating priests and people who live forever and you'll win a Nobel Prize. Write it in English about an intricate interstellar civilization and the myriad ethical problems it entails and you'll be dismissed as a "genre" author.

That is indeed the essence of magic realism. Write it in Spanish about levitating priests and people who live forever and you'll win a Nobel Prize. Write it in English about interstellar civilization and you'll be considered a "genre" author.

It's human nature to label people, and it can't be helped I gues. I can't recall when ever a religious tinted novel ever won a nobel prize, but to my knowledge all religious novels are a bid of science fiction imagen if they would actually explain why deep meditation would result in people to hover around, such results could only halusanated when they 've smoked the ritual tobaco or sucked the ritual toad. In real live that guy should have to be in orbit to levitate and that's the simple truth.

The story is precisely about what life would be like if that one thing about the universe--the impossibility of FTL travel--were different from our reality
What is reality if not relative before baude and pascall if I would have asked what was in the emptiness of your hand you would proberly say absolutley nothing, now you know there is a interesting mix of oxygen and nitrogen in it, that in the right way could be pushed to produce lift. And if I would ask you now what is in the emptiness of space you proberly say there is nothing