###### Why do we assume that travelling faster than the speed of light necessitates time travel?

We can show that it is possible to travel backwards in time if you can travel faster than the speed of light according to the theory of Special Relativity. The fact that time travel becomes possible is actually meant to show that traveling faster than light

###### If you were traveling at .5C, how much time would pass for a traveler in 1 light year of travel?

Let's see here. The equation for time dilation as a result of velocity is[math]t = t'*sqrt(1-v^2/c^2)[/math]Really, what we're interested in is the sqrt(1-v^2/c^2) as this will give us the percentage of the time dilation by setting c = 1.[math]sqrt(1-.5^2/1^2) = sqrt(1-.25) = sqrt(.75) = ~0.866[/math]So, time is dilated to about 86.6% of

###### Can we make a rocket which travels faster than light?

When speed of any particle become comparable with the speed of light, Einstein's relativity is relevant.If you use Einstein's velocity addition formula for any arbitrary direction (X,Y,Z- axes) you will find an interesting fact that no particle will exceed the speed of light.Even in a frame where light is moving with

###### Would I see the speed of light as 'c' even when I am running at the speed of light?

Even if you travel at 'c', light would still appear to move at speed of light wrt to you. To explain this, we need to consider the space as a 5 dimensional region.(5th : flexible)When you travel at the speed of light, the space before you expands

###### Do gravitational waves travel faster than the speed of light?

Answer to: Is there a speed like the speed of light other than the speed of the gravitational wave?I'm not sure what you mean. Are you asking if there is another speed which all observers in different inertial reference frames will agree

###### What is inertial frame?

The frame of reference whose a = 0 i.e acceleration is zero is called inertial frame of referenceIt can also be defined as a frame where Newton's laws of motion are valid.Example : A car standing still or moving with constant velocity

###### Does red light travel faster or violet light?

No it doesn't. In vacuum, the entire electro magnetic radiation has the same velocity. Once it enters a medium, short waves (violet) are more prone to absorption and scattering whole long waves (red) are more likely to penetrate. Hence the red signal can be seen thro mist more easily than a blue or violet signal

###### If a light source is travelling at the speed of light, does it emit light?

The answer to your question is a simple yes it does. An observer will observe the emitted light and would MEASURE its speed as

###### What would happen on a carousel moving at the speed of light?

Quora is full of questions (and answers) to

###### In layman's terms, why can't we go faster than the speed of light?

[NEW SECTION added 2018–11–18 16:07 UTC]Short answer:All motion is relative. The speed of light is a constant, independent of the motion of its source.When you combine the two, you get special relativity (SR).In SR you find that as the speed

###### How is the speed of light the highest possible speed?

It is not the light that sets the limit, its the speed at which the light travels. Light travels at the speed of light which is 299,752,458 m/s. If the gravtational waves ad been discovered earlier this speed might have been named as speed of gravitational waves. So at last it's not the light it's the speed of

###### If nothing travels at the speed of light except light, how can a black hole also pull light into itself?

If nothing travels at the speed of light except light, how can a black hole also pull light into itself?The statement that starts the question is not correct. Phenomena other than light travel at speed C.A Black Hole is a postulated phenomenon in an attempt to explain the proven abnormal condition located in

###### If, at the speed of light time stops, how do photons have motion that is measurable?

Different frames of reference.Time stops in the frame of reference of a photon - a massless particle travelling at the speed of light (as seen by other massive observers.)For observers that have mass, the photon is travelling at the speed of light - although the observervers will experience that photon to have different wavelengths (or energy).

###### How is the speed of light calculated because of its incredible speed?

See picture: http://www.chegg.com/homework-he...As the gear spins faster, the light will take time to travel and be blocked by the time it gats back to the gear.

###### Is air faster than light?

Ok first of all, call to mind a commonly used phrase based on Einsteinian principles

###### How far are we from creating a spaceship that travels almost as fast as light (photons)?

The question should be analyzed as how close are we to being able to transfer a human consciousness into an electronic neural net or similar form, which can be encoded as information and sent at the speed of light (as light, in fact).I, myself, do not want to make a journey that way. I'm

###### Does the speed of a photon equal c or 0 when observed by another photon moving on a parallel trajectory?

Much of what we have today in the form of viable, testable, reliable theories of various aspects of physical reality began as a thought experiment. The notion that a photon has a point of view, or can

###### How fast can the speed of light potentially travel?

No.It isn't really the speed of light. After all, light doesn't always travel at c. Better to think of c as the speed of causality, the maximum rate at which a signal from one event could influence other events.If causality is rigidly respected, then c provides a hard upper limit on everything.

###### If you were traveling at the speed of light how long would it take to travel around the earth?

The question needs to say in what frame of reference.In an inertial frame on earth then [the circumference of the earth] /[the speed of light] = 40075000m/299 792 458 m / s = 0.133676 s.Light has no time and we cannot go that fast so no

###### If light travels at the speed of light, then can light go back in time?

Light is travelling at the universal speed limit (3e6km/s) and has no mass. This means that light will not experience any change in time if it were to travel from one end of the universe to the other.In other words let's put

###### Do souls travel at the speed of light?

Assuming that souls exist, they would be tied to extra-dimensional relativity. That means something like quantum entanglement tying the soul to the location it currently is, and upon the decease of the living creature, instantaneously traveling to another realm. That means that yes, they

###### Would time dilation alter our chances of discovering extraterrestrial life?

Depends on the kind of extraterrestrial life.If the extraterrestrial life is not much different from earth's bacteria and is present on any of the planets in the solar system, then time dilation need not play much of an important part in finding

###### Are there galaxies traveling at light speed?

No, nothing can travel at the speed of light, but, from our perspective, it can appear to travel faster than light.The speed of an object is determined by the distance it moves from it's current location to another location, within a period of time. The speed of light is about 300 000 km/s. No

###### If light has absolutely 0 mass, then why doesn't it travel instantaneously?

Because when it flies, and *because* it flies, it stops being zero-mass!

###### Will a vacuum affect how the speed of light travels?

Light can change speed, even in a vacuum, a new paper reports. The discovery could change the way we think about one of the constants of the universe.

###### What makes the light travel faster than anything else?

All Quantum Fields "propagate change" at the speed of light as shown in Quantum Field Theory (virtual processes can "travel" faster but they don't carry information). Particles are excitations of these fields and thus all should travel at the speed of light. However, because the Higgs Field is interacting with many particles not all do.Particles like Quarks, electrons,

###### What makes light move? Why isn't light still?

Energy and momentum conservation laws dictates the motion of light. Light is the emitted energy from a source (i.e. atom) as an outcome of some process like jumping of electrons from higher energy state to lower energy state. Depending on the process by which light is emitted, it consist of wide

###### How much time at the speed of light would it take to reach Andromeda Galaxy?

The distance from Earth to the Andromeda Galaxy is about 2.5 Million Light Years. That, of course, is also the time it was take a Light Speed spacecraft to travel that far, even though no material object could travel that fast. Note that the diameter of Andromeda is about 10 %

###### Is it impossible to destroy the universe since it's expanding faster than the speed of light?

Assuming our modern theories of moder physics, dark energy and dark matter are correct, there will be tons of galaxies that are forever out of our reach, so no, we can't go around destroying every planet and star in the universe.That being said, we are fairly certain that the universe will end all on its own.

###### I just saw we are 6 light years away from a "super earth". Assuming we can travel as fast as our current rockets can go and not refuel, how long would it take us to get there?

I just saw we are 6 light years away from a

###### What if we accelerated the Andromeda Galaxy to near the speed of light at us?

If it does happen, the outcome would be complete, utter chaos!The gas giants in our solar system will explode!The rocky planets (including Earth) would spin out of their axis uncontrollably!Pluto would pulverize the Moon and smash it to pieces!It will not be a pretty picture, that's for sure!

###### What is the Mach equivalent of the speed of light?

Assuming room temperature of 20 C, speed of sound in air is given by the equation 331+0.6T = 343 m/s. The speed of light is defined exactly as 299792458 m/s. So, dividing 299792458 by 343 gives roughly 874030.5.

###### If nothing is impossible, can we move faster than light?

We know that the statement "nothing is impossible" is false.It is impossible to know both the position and momentum of a particle within a certain limit. If you precisely know the momentum of a particle it is impossible to know the position of the particle within

###### Does light travel forever?

It depends on the medium of propagation of light .we can consider two cases herepropagation through vacuum -as we know vacuum offers no resistance to light leading it to have a highest velocity ( 299,792,458 metres per second) in vacuum .therefore

###### Could there be a theoretical medium through which sound travels at the speed of light?

Well, yes, and no, it depends how you look at it. To start it is important to note that it was actually proven that sound can travel faster then the speed of light in vacuum. This was done by a physicist of the name of William Robertson along

###### Can't light reach us quicker if it is emitted by something coming towards us near the speed of light?

Nope! The velocity of light is a universal constant in nature and no matter how fast the emmiting source is moving, light velocity will ALWAYS be measured as being equal to c=300,000 km/s.This is known as Einstein's second postulate in special relativity theory:

###### Why can't an object travel at or faster than speed of light?

The premise of this question is false. [math]E=mc^2[/math] is not about objects traveling at the speed of light, nor is it about producing energy in any shape or form.Rather, [math]E=mc^2[/math] expresses an equivalence between rest mass and energy, with [math]c^2[/math] being the

###### What would happen if a train travels at the speed of light?

Consider you are in the train which is travelling at a speed of light. You could observe everything happening around you but you cant move. This is because when you move the velocity of your movement gets summed up with the velocity of light which ultimately leads to

###### Can light travel slow?

It depends on what you mean by slowLight can be slowed down by matter that obstructs its course such as air but by an insignificant amount so it can't really be defined as slow.Light also takes 30% more time to travel through water

###### Theoretically, if you could move a powerful telescope faster than the speed of light away from the Earth, could you see back in time?

If faster-than-light travel is possible, then not only is

###### If travelling at the speed of light is impossible, how do photons travel at the speed of light?

The speed of light, (or the speed of a photon) in a near-perfect vacuum is exactly 186,282 miles per second.   We perceive photons (light) traveling at this speed because they are   massless, or have no ‘weight' (but they do have kinetic energy,

###### If time has a speed, can light travel faster than it if time elapses faster?

You cannot calculate the speed of time. It is not absolute, it depends on the surroundings and the speed with which you're traveling.No matter how fast or slow your time is flowing, you'll never notice the difference because time decides your flow. An

###### The fastest speed known is the speed of light. For interstellar travel or exploration, is the speed of light too slow?

It's both too slow and too fast depending on whose making the observation.For a person travelling at near light speed, it's really too fast because the person could get to a star in a galaxy a billion years away in a matter of seconds.For a

###### What would happen if the speed of sound suddenly doubled the speed of light?

The speed of sound in a material is how fast a pressure wave propagates in the material. At microscopic level it means that if a molecule in the material is pushed by something, it will push the molecule next to it, which will push

###### How can we stop light?

A Bose Einstein Condensate (BEC) can stop a weak light pulse completely and store it by transforming the quantum states of photons into the spin quantum states or spin waves due to the outermost electrons of atoms that constitute the BEC. One can also recover this light pulse by tuning the BEC via an external magnetic field.