Faster than light Definition and 17 Discussions

Faster-than-light (also superluminal, FTL or supercausal) communications and travel are the conjectural propagation of information or matter faster than the speed of light.
The special theory of relativity implies that only particles with zero rest mass may travel at the speed of light. Tachyons, particles whose speed exceeds that of light, have been hypothesized, but their existence would violate causality, and the consensus of physicists is that they do not exist. On the other hand, what some physicists refer to as "apparent" or "effective" FTL depends on the hypothesis that unusually distorted regions of spacetime might permit matter to reach distant locations in less time than light could in normal or undistorted spacetime.
According to the current scientific theories, matter is required to travel at slower-than-light (also subluminal or STL) speed with respect to the locally distorted spacetime region. Apparent FTL is not excluded by general relativity; however, any apparent FTL physical plausibility is currently speculative. Examples of apparent FTL proposals are the Alcubierre drive, Krasnikov tubes, the traversable wormholes, and quantum tunneling.

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  1. Delta2

    I Entanglement and FTL signaling in professional scientific literature

    According to professional scientific literature and to our best understanding, are there any suggestions that entanglement might imply some sort of faster than light signaling between the entangled particles? I know that according to relativity nothing can travel faster than light, but what...
  2. M

    If you are moving in a ship at FTL, could a pilot react at FTL?

    Faster than light travel is most likely impossible (at least in this dimension) BUT hypothetically I was thinking back to Star Wars: The Force Awakens. At the near-end of the movie, Han Solo, Rey, Chewbacca, Finn and BB-8 get through Starkiller Base's shield by exploiting a loophole. The shield...
  3. M

    I Is this explanation of "space itself expanding" correct?

    Hi, I always used to struggle with the concept of "space itself expanding" (didn't Einstein say that the aether did not exist?) until one day an idea struck me that seemed to explain it all, without any need for complicated math. After talking about it with others, I got some great feedback...
  4. RosutoTakeshi

    B How many times faster than light is this?

    Ok so I'm having trouble understanding how to calculate this If an object is moving so fast that it would take... "Hours for light to catch up to it" .. how fast would it have to be moving? Let's say it would take 2 hours for light to catch up to it. What kind of speed are we looking at...
  5. A

    What do you think of this FTL/time travel engine?

    So, I have this idea for the FTL engine for artistic purposes and I wanted to ask if anybody could point out it's flaws. I would greatly appreciate if you were willing to discuss them further. It is just a rough summary, so if you want me to disclose more details, ask away. The idea is as...
  6. N

    I What time structure supports info moving backward in time?

    This of course is speculative, but IF faster-than-light travel (or wormhole tunneling or some other exotic means) was found to be able to communicate information from the future to the present, what would that indicate about the structure of time? Some might argue that indicates a block-type of...
  7. K

    B Exactly why FTLC is impossible with entangled photons?

    It’s written almost all physics books and courses that entangled photons can’t be used for faster than light communication. The question about used entangled photons to communicate faster than light has been discussed before, but I didn’t get exactly why faster than light communication with...
  8. ISamson

    Faster than light: Instantaneous lever

    Hello. I have been thinking on faster than light things. I thought about: chemical engines, lasers, wormholes... All that kind of cool, advanced physics. But, I stumbled on faster than light mechanical actions. I thought about a lever: first class, if you wish, if you apply a force to one side...
  9. C

    B Why doesn't this FTL communication scheme work?

    If Alice and Bob had a large number of particles entangled together (with state of either 0 or 1), could Alice send information by breaking the entanglement of particles with state of 1 (by flipping the state for example) so that Bob measures 50% of particles to be in the state opposite of 0...
  10. mpolo

    Can electrons move faster than Light?

    I just read this article and it sounds like they are claiming that there are electron currents moving 6 times the speed of light? Am I understanding this correctly. The article title is "Faster-Than-Light Pulsar Phenomena"
  11. MiLara

    B Information traveling faster than light

    I know there is a modern paradigm that states that nothing, including information, can travel faster than the speed of light. (With exception to quantum entanglement, but I'm not going to pretend like I know the exact details of that subject). Thought experiment. Imagine there are a series...
  12. M

    I Do distant planets move faster than light relative to Earth?

    From the observation point of Earth, you can say that the sky "moves" while the Earth is still. From this point, an observer on Earth would see a distant galaxy travel a circumference millions of light years lomg around the Earth in only a day - resulting in a velocity faster than light. Special...
  13. Seanra

    I My lecturer says "Special relativity is absolutely wrong"

    Hi guys In an assignment I wrote for university I was penalised for claiming that FTL neutrinos would violate special relativity. Below is the relevant part of my assignment and the response from my lecturer. Could somebody please explain what he could mean by that because as far as I can...
  14. Jim Hasty

    Quantum communication

    Quantum Communication. All systems described by quantum mechanics can display so-called entanglement, for example, the spin of one electron cannot be known in advance of a measurement yet will be perfectly correlated with the other, even if it is in a distant location. This has recently been...
  15. AlexDB9

    Faster than light travel and destination's time

    I've read that faster than light travel is possible if we manipulate the space around the craft, but the energy needed is on the order of the sun's output. So, even if not practical, since theoretically it is possible I want to ask what happens to our destination's time. As I understand at...
  16. Jesus

    Superluminal propagation of fields

    I am reading about the Velo-Zwanziger problem in which particles with spin higher than 1 propagates faster than light when the particles are coupled with an electromagnetic field. In the original paper: G. Velo and D. Zwanziger, “Propagation And Quantization Of Rarita-Schwinger Waves In An...
  17. A

    Information transmitted at speeds greater than C

    Hello, a question for all of you with its experiment. If I have a material that has a Bulk modulus higher, the diamond type (442 GPa) if I create a tube of diamond along 1 miles (or length less) with appropriate supports to decrease as much as possible the friction. At the same time I have a...