"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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Communication via teleportation/entanglement (FTL communication)

I know this has been asked many times, but I have a hard time "crystallising" it in my mind. First: let's say we teleport a DVD (with quantum teleportation). Isn't this FTL communication? Second: ...
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Imagine I'm on a spacecraft that was accelerated to 1.0$c$ could I only move backwards? [duplicate]

Imagine I'm in a sapcecraft1 that is moving with 1.0$c$ or at least is so close to that speed that a few miles per hour would just be left to reach $c$. So when I'm traveling now in the direction ...
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Can the Higgs field and gluon binding energy be manipulated to reduce the mass of an object? [on hold]

I've read that the Higgs field gives mass to elementary particles. I've also read that the mass of protons and neutrons are more effected by gluon binding energy. If both were somehow manipulated, ...
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Dark energy and gravitation force

This might be a silly question to ask but still I had to ask. we know that gravitational force between two galaxies are quite less as compared to the dark energy. so two galaxy are separated at speed ...
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74 views

Faster than light travel…? [duplicate]

So - Black holes possess a gravitational force so great it can pull anything in. Including light. So placing these side by side, If I were to shoot a laser pointer out of a cannon at a black hole, ...
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Is Dark Radiation Superluminal in speed?

In recent news http://www.kolkata24x7.com/tech-news/universe-expanding-faster-than-expected scientist have observed that the universe is expanding 5 to 9 percent faster than their calculations. ...
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Speed of Dark experiment, does it *really* travel faster than light? [duplicate]

I have seen many folks doing this Moon shadow experiment concluding that shadow from point A on the Moon can travel to point B on the Moon faster than light. What I fail to understand here (and I am ...
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Can't quantum teleportation be superluminal some percentage of times?

I apologize if this is a really silly question. In the (textbook) quantum teleportation algorithm, in the step right after Alice has measured her system but before she has sent her classical ...
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Why can an object not reach the speed of light by falling in a gravitational field with constant acceleration?

I recently learned in school that the gravitational potential energy of an object is equal to $mgh$. I also learned that the kinetic energy of an object is $\frac12 mv^2$. If an object falls in a ...
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Path integral (sum over paths where $v>c$) [closed]

The path integral formalism is used to get for example the propagator of particles. In this formalism we integrate over all mathematically possible paths (and weight them with the non-relativistic ...
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92 views

Do Gravitational Waves disprove superluminal Alcubierre drive?

I am not a physicist. But... does the rate at which gravitational waves travel set an upper limit to the "speed" of a ship propelled with Alcubierre drive? Or does it present a relativistic trick (...
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What's the problem with light traveling at speed higher than $c$?

I'm trying to understand how Einstein concluded that time is relative based on thought experiments such as a torch attached to the end of a rocket. Based on answers to questions like this one, this ...
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Multiple Objects at Constant Speed

Imagine 1 million objects travelling in space, at a constant speed, along an imaginary line. They don't deviate from that line for the sake of this argument. Now, object 1 has a velocity of $v_{1}=1$ ...
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2answers
377 views

How to achieve speeds faster than light? [duplicate]

So, I heard that all speed is relative. And that nothing can travel faster than light. Then I guess it is OK for a spaceship to leave Earth at 0.6c constant speed. And what if an other spaceship were ...
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Can information be sent faster than speed of light [duplicate]

I just had this idea one day and I decided upon a thought experiment to verify it. Imagine 2 people A & B sitting on two sides of a pipe which is stretched to a length of 3x10^8 m. The pipe is ...
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Can ray of light reflect from another ray? [closed]

Consider three light rays 2 parallel 1 perpendicular and source of the perpendicular ray is in between other two. If ray of light reflect from the other two rays then it must be like standing in front ...
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Incomprehensible substance: information traveling faster than light? [duplicate]

Say I'm holding a rod composed of an incomprehensible solid, and this solid rod is 1 light second long. Then say I poke you with the rod and at the same time I flash a light on you. If light is the ...
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How can muons travel faster than light through ice?

When a neutrino traveling through ice hits and interacts with an oxygen atom, muons are created. Cherenkov radiation can be created when muons travel through ice faster than light and create a ...
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If space can expand faster than light why can't gravitational wave?

I heard that gravitational wave is the measure of stretchiness of space time, so since there is no limit to how fast space can stretch what about gravitational wave?
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Does antimatter travel faster than light

I have read in the answers here that an electron traveling backwards in time would behave as a positron. I also read in another there that antimatter is matter traveling backwards in time As far as I ...
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107 views

Objects travelling relatively to each other faster than light?

When we say that something is travelling a certain speed, it's really travelling that speed relative to the Earth. When saying the speed of anything, it is, for the most part, relative to something ...
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Is General Relativity compatible with relative speeds bigger than $c$ between two inertial frames?

My question is motivated by a remark done by Tegmark in his book "Our Mathematical Universe". He says that GRT does not prove that relative speeds between material points are always smaller than c. It ...
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If there is no speed limit on space-time compression, why do gravitational waves travel at light-speed?

From what I've read about spacetime and general relativity it seems there is no limit on how quickly space-time can be compressed or expanded. Why then gravitational waves are limited to light speed? ...
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What will be the weight of 1kg body at event horizon and then at the centre of black hole?

As we know if we go to the centre of the earth our weight will decrease gradually and at one stage we feel weightless.... Then what will happen if go to the event horizon then to the centre of black ...
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Speed of stuff falling into a black hole, beyond the event horizon [duplicate]

We know the escape velocity from the event horizon (EH) $= c$. Anything that crosses the EH is destined to reach the singularity. Whether the escape velocity (beyond the EH) can be calculated, or not, ...
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If I turn the tip of a 100 light years long pencil, the other end instantly turns , or it takes 100 years? [duplicate]

If a civilization could build a strong , lightweight tube, hundreds of thousands of kilometers long , could theoretically use it to communicate faster than light, simply by rotating it at one end , ...
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Beyond the speed of light [closed]

Suppose that I can walk/run/travel (not sure if this matters) faster than the speed of light. What would I experience? I know speed of light is a constant and cannot be reached. If someone were to ...
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Does light accelerate as it nears a black hole? [duplicate]

As light is affected by gravity ( gravitational lending and black holes), it would seem that gravity causes acceleration. Acceleration has two parts: direction and magnitude. It is clearly evident ...
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Is the maximum possible measurable velocity = 2c

What is the maximum velocity that can be measured between two objects? Is 2C the correct answer? Two photons (A & B) are emitted simultaneously from my position; photon A going north and photon ...
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If a car is travelling faster than the speed of light, do the headlights still work? [closed]

If a car is travelling faster than the speed of light, do the headlights still work? If you can help because i really need to know i am going on a trip with my car tomorrow!
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Front velocity and Superluminal group velocity

In some cases, according to Wikipedia, the envelope of a gaussian beam can go faster than speed of light hence leading to superluminal group velocity. However, the signal/energy still propagates at ...
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Signal travels with speed greater than light breaks causality

Signal can't travel at speed greater than light speed in vacuum which is a assumption of special relativity. But if a signal travels at speed greater than $c$ then it will violate causality. I tried ...
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What field property may allow faster than $c$ speed?

What field property may allow faster than $c$ speed? Is there theoretical field or what property it needs to have to allow wave speed larger than $c$? What is the speed of the gravitational wave? Is ...
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Rate of expansion of universe during big bang [duplicate]

We say big bang was the explosion not in the space but of the space itself that took place in a fraction of seconds. Speaking practically, we say the universe has no edge and is infinite. If the ...
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Is the GW150914 signal consistent with a superluminal gravity wave burst?

I've been following the news about the detection of gravity waves with interest and had a question for those with a physics background. I've gathered that the preferred explanation for GW150914 (Fig 1)...
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Effects of FTL travel on time [closed]

The twin paradox explains, using relativity theory, what happens to a person travelling close to the speed of light. When he returns to Earth, he finds his twin brother much older because the ...
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Why relativity doesn't rule out Inflation theory? [duplicate]

Nothing can go faster than the speed of light, then how at the time of inflation space expanded faster than the speed of light? Clearly universe had already begun at the start (10−36 seconds) of ...
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How is it that we can send signals faster than the speed of light?

I came across this while reading The Feynmann Lectures on Physics (Vol.1,Ch.7)- According to Newton, the gravitational effect is instantaneous, that is, if we were to move a mass, we would at once ...
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Speed bigger than light? [duplicate]

We know, according relativity theory, no information or matter can travel with velocity bigger than light. However, consider the following situation: a completely empty water hose is hypothetically ...
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Information can't travel faster than $c$

When we say that information cant travel faster than light, we mean that phase velocity can go beyond $c$ but the group velocity can't. Hence, we say that a plane wave carries no information. What I ...
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Do gravitational waves travel faster than light?

In Feb 12, 2016 edition of Times of India, an article read [with the discovery of gravitational waves, we will be able to] Track Supernovas hours before they're visible to any telescope because ...
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Is it accurate to say that nothing can travel faster than $c$ in a GR context, where more space can be created?

Years ago, my brother and I had an argument where I was trying to convince him that nothing could travel faster than the speed of light. I was pursuing this in the context of Special Relativity. My ...
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My theory to travel near the speed of light. Why will this theory not work? [closed]

Why can't a spacecraft travel near the speed of light? Here's my theory. We assemble the spacecraft in the Earth's orbit just like the International Space Station, each time, equipping it with lots ...
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Group and phase velocity - why can the latter be faster than light? [duplicate]

The phase velocity can be faster than light. Some argue that the phase velocity doesn't convey information, but this doesn't convince me. We can emit a wave of a single one frequency. Then it will ...
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Do wormholes only allow FTL travel in “folded” spacetime?

Faster than light wormhole travel depicted in science fiction and in popular science articles seems to assume that rather than being flat (with dimples centered around large masses), spacetime is ...
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Telescopes and faster than light travel [closed]

If sometime in the future we master faster than light travel, could we solve past crimes by warping to a place in space where the light from Earth is just arriving from that time period and using a ...
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Can absolute speed of object be measured? [closed]

Let's say there are two objects in space - Station and huge non-transparent sphere. Sphere starts to move from station 5000 km/h. Inside the sphere, beam of light is produced in direction the sphere ...
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Is it possible to go faster than the speed of light in vacuum?

If it is possible for particles to go faster than the speed of light in certain events, would it be possible to create a situation in which the barrier of the speed of light can be crossed?
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Getting an object to travel at or near light speed by adding velocities [duplicate]

Firstly I'll just give a brief example of where my query came from. I was watching the episode of Futurama where Bender meets God after being fired from the planet express ships torpedo tube. The crew ...
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Do photon inside event horizon exceeds speed of light?

Event horizon is a region of space whereby nothing with information can escape, so I imagine that a photon falls into this region of space does it accelerates toward the singularity if it exists? Do ...