How far is the nuclear fusion force

Is there a science-based travel system for a spaceship that is faster than light?

I've thought a lot about this topic and still haven't found a plausible FTL mechanism. Here is a brief overview of key features of the "standard" mechanisms used in science fiction. None of them are scientifically based, but some of them are in principle plausible.

This category of FTL transport mechanisms uses known facts since general relativity alone allows a very broad class of spacetime deformations. For almost any form of spacetime one can find a mass distribution that can produce it. This enables solutions such as the famous Alcubierre drive or movable wormholes. However, there are three very serious problems.

Problem of exotic matter

It is true that the solutions to the Einstein equations almost always exist, and some of them allow FTL travel, but almost always it requires what is called exotic matter. It is exotic in several ways: it has either negative rest mass or tachyonic properties. This poses many problems: in some cases, such matter can be created spontaneously from the vacuum, generating energy in the process. In other words, its existence would make our vacuum unstable. In other cases this problem is absent, but such a matter is likely to allow direct travel with superluminars and therefore necessarily time travel. (At best, we want wormholes to give us shortcuts to stars without breaking causality, which is always worrying.) In all cases, such a matter is unlike anything we've come across, and there is no good reason believed to be the case will be discovered in the future.

Someone says that quantum effects like the Casimir Effect can play an exotic crowd. This seems very unlikely to me as they are tiny compared to the residual masses already present in the system. For the construction of a warp drive or a wormhole we need effects that are comparable or larger than the other masses. If I wanted to introduce exotic mass into my universe, I would probably posit that new particles of these properties have been discovered.

Problem of density

Another big problem is that spacetime is only deformed at very, very high densities. Even with core densities of around 10 17 kg / m 3 there has to be an object the size of a neutron star to do anything at all. Much higher densities would likely be required for the FTL construction. This means that some form of reasonably stable ultra-dense matter would likely have to be introduced to make this form of FTL possible.

Problem of too much mass

Reaching wormholes or warp bubbles on a meter or kilometer scale would likely require masses comparable to the solar mass.

Warp drive

  • There is no evidence to suggest that there should be a required high density exotic mass.
  • Automatically allows time travel in the universe.
  • Probably requires the existence of a stable, high-density exotic matter such as im Orion arm proposed magmatter. It is unlikely that we can build it solely on the basis of atoms. (This implies that it probably cannot be based on a field that is just "on", as is the case in Star Trek. The energy required for such a field would far exceed any energy spaceship made of atoms , even in the form of antimatter.)
  • Warp bubbles large enough to contain spaceships require enormous energies at very high densities. Civilizations capable of their construction would likely find it easier to "rewrite" themselves in high density objects and use smaller bubbles.

Wormholes

  • There is no evidence to suggest that there should be a required high density exotic mass.
  • Wormholes would likely have a mass comparable to planets or even stars.
  • Do not allow time travel automatically. It can be prevented by the Visser Effect, as they called it in Orion's arm. However, the discussion about this effect is broader, including some scientific articles on the subject. Nicely explained on the Anderson Institute web

    It is believed that it may not be possible to turn a wormhole into a time machine. Some analysis, using the semi-classical approach to incorporating quantum effects into general relativity, suggests that a feedback loop of virtual particles would circulate through the wormhole with increasing intensity and destroy it before information could be passed through the wormhole according to chronology Presumption of protection.

  • Should be transported on the spot at sub-light speed.

Jump-Drive is used, for example, in the Battlestar Galactica- Series used with no explanation of the mechanism. A similar jump drive is used in Mass Effect used , where they basically offer this mechanism: The theory of relativity does not forbid the existence of tachyons - particles that always move faster than the speed of light. You can go back in time and break the causality, but that's not a problem in principle.

The jump drive works in such a way that the spaceship changes the local Higgs field, which leads to a change in the rest mass of the particles of the ship. Eventually all particles gain an imaginary rest mass and become tachyons. Then they move faster than light.

  • Requires the existence of tachyons. There is currently no evidence that they should exist.
  • Requires the viability of changing the residual masses to imaginary values ​​by changing the Higgs field. (Probably not really possible, but plausible.)
  • Automatically enables time machines.
  • Requires an incredible amount of energy.
  • It is very unlikely that the ship and crew will survive the tachyonic state or transition to it. When the residual masses change, the binding energy of each atom drops or changes wildly and the atoms become much larger. The same thing happens with the atomic nuclei.

The subspace / hyperspace idea assumes that it is possible to leave our spacetime in another space where the speed of light would not be the limit. The biggest problem is how to transition into hyperspace. We know how matter behaves up to very high energies (hundreds of GeV), and we have not yet seen anything similar. From this we can deduce that a transition into hyperspace would probably only take place with a very high-energy mechanism. This poses problems similar to those of the space-time manipulation mechanisms.

  • There is no evidence that hyperspace should exist.
  • Doesn't necessarily allow time travel. The structure of hyperspace could determine what really is "now". This violates the equivalence principle, but only if it is about hyperspace. (And therefore it does not contradict the experiments carried out so far.)
  • If the transition to hyperspace is possible, it will likely require energies so high that we have not yet noticed it. This could be prohibitively difficult to construct.

It's easy here. Although it is widely used in science fiction, it is shown that quantum entanglement cannot transmit data faster than light. Wikipedia:

However, it is not possible to use this effect to transmit classical information at a speed that is faster than light

There is a very extensive and scientifically reliable overview on the Internet of Project Rho. (Although some of the FTL drives listed are not very plausible - and the author admits it.)

Race of lightness in orbit

As far as I remember, the BSG FTLs were given off-screen by the manufacturers to take advantage of wormholes.

epsilon

I enjoyed reading your well thought out answer. One thing that nobody mentions about FLT is navigation. For one, how the hell would you stop? It appears to be required to discharge an infinite amount of energy, just as accelerating to FLT requires an infinite amount of energy - or at least an unlimited amount of energy.

Celtschk

"But such matter will probably make superluminal travel possible" - I thought this is exactly the point of a space system that is faster than light.

Irigi

Thanks, I'll rephrase it. I wanted to point out that if you let superluminar travel in any direction, it automatically means time travel. (Wormholes avoid this problem as you'd rather change distances in space than travel superluminar.)

Joshua

The thing about the warp drive field is that the required energy density is very high, but it contains negative energy components. It may well be possible to reduce the total energy to something manageable. The arithmetic in more complex fields has already reduced them from half the mass energy of the galaxy to a few masses of Jupiter.