"Faster-than-light", also known as superluminal velocities, refers to any sort of travel at a speed greater than the speed of light. Prohibited in mainstream physics due to the Special theory of relativity.

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About the nonlocality of QM and faster-than-light/backward-in-time machines

The fact the quantum mechanics is nonlocal is known already for a long time, since the Bell works (1966 and later) and the Aspect's group experiments confirming the Bell-type CHSH inequality (1980 ...
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Question about the no-clone theorem

The quantum no-clone theorem states that one cannot "build" a perfect cloning device for arbitrary quantum systems. There also exists a famous thought experiment where Alice transmits information to ...
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Speed of approach between image and object

A plane mirror image approaches the object at the same rate the object approaches the mirror. So the speed of approach is twice the speed at which the object approaches the mirror. If the object ...
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Navigating a Time Machine

Notes: The background for this question is working out details of a sci-fi story. Answers to the effect of "time travel isn't possible" or "FTL isn't possible" are therefore not helpful. I'm looking ...
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Status of experimental searches for tachyons?

Now that the dust has settled on the 2011 superluminal neutrino debacle at OPERA, I'm interested in understanding the current status of experimental searches for neutrinos. Although the OPERA claim ...
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Would warp bubbles emit gravitational Cerenkov radiation in general relativity?

Inspired by the gravtiomagnetic analogy, I would expect that just as a charged tachyon would emit normal (electromagetic) Cerenkov radiation, any mass-carrying warp drive would emit gravitational ...
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Alcubierre warp bubble effect on gravity and space

I read the question Faster-than-light communication using Alcubierre warp drive metric around a single qubit?, and these questions came to mind: What kind of impact would an Alcubierre warp bubble ...
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What's going on along the “sides” of an Alcubierre warp bubble?

The models/depictions I've seen of warp bubbles show space compressed ahead of the bubble and expanded behind, so that the space inside the bubble moves with respect to the space outside. If that is ...
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Does FTL signaling allow signaling in the past at the cost of arbitrary precision?

In a recent paper (http://link.springer.com/chapter/10.1007/978-3-642-30870-3_53#page-1), G. Szekely and P.Nemeti wrote the following. Let us consider two reference frames A and B initially, at event ...
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Can be this configuration used to faster than light communication?

I know from some popular science articles or books that is possible to make special pairs of particles which are quantum entangled. Then each of entangled particles can be moved to different places ...
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Could one transmit a signal with equally-tuned casimir plates across the quantum field?

It seems, one could exploit the Casimir effect to send messages across arbitrarily-large distances with carefully-tuned Casimir plates. Obviously, relativity would preclude FTL information transfer, ...
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Would superluminal signalling imply the violation of the No Cloning Theorem and unitarity?

The no-cloning theorem implies that we cannot use entanglement to send signals faster-than-light. Has anyone proved the contrapositive? That is, if we are given a system for superluminal signalling ...
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Theoretically if you passed the speed of light, would there be a sonic boom equivalent?

I know that it is technically impossible to reach the speed of light since the mass of the object traveling would reach infinity. Despite this if it were possible, would there be some sort of ...
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Impulse travelling faster than light

There have been conducted many experiments in which light impulses traveled faster than light like the one in Princeton in 2000. This phenomenon has something to do with quantum entanglement. Does ...
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Scenarios of subverting causality with “superluminal cables”

Due to insistence of the community, the original question is separated to three parts. The basic scenario for a causality-violating signal transmission with two constant-length and symmetric (in rest ...