### How slow can light go?

In some special substances, it was possible to slow the speed of light to just a few meters per second - incredibly slow compared to the speed of light in a vacuum. In some special substances, it was possible to slow the speed of light to just a few meters per second - incredibly slow compared to the speed of light in a vacuum. In some special substances, it was possible to slow the speed… Read More

### Is the universe moving with the speed of light?

In fact, the farthest galaxies we can see are receding at several times the speed of light. While moving above the speed of light is forbidden in the Special Theory of Relativity, in this case it is space itself that is expanding at that speed. In fact, the farthest galaxies we can see are receding at several times the speed of light. While moving above the speed of light is forbidden in the Special Theory… Read More

### If special relativity states that the speed of light is a constant how can refractive index be an indication of a change in the speed of light?

The relativity statement refers specifically to the speed of light in a vacuum.

### What accurately states the claim of special relativity with respect to the speed of light?

The speed of light in a vacuum is constant, and it is the same for any observer.

### Is the speed of light faster in a liquid?

No. According to special theory of relativity, the speed of light in all inertial mediums remains the same as that in the vacuum.

### If you turn on a flashlight while on a spaceship going the speed of light what speed is the light from the flashlight moving at?

c - Light goes at c in all frames of reference according to Special relativity

### Where does a photon get its speed from?

Nowhere. A photon must travel at the speed of light so it starts with that speed when it is created. This is the origin of the theory of special relativity.

### Is it possible for a human to travel faster than the speed of light according to scientist?

According to special theory of relativity no body can be accelerated from Rest to more trhan speed of light. A body as it approaches the speed of light its mass increases and thus would require infinite energy to reach speed of light.

### What is the speed of a radiowave?

In free space, radio waves travel at the speed of light. In a material, such as co-ax cable, the speed is much lower, perhaps as low as 0.6 of the speed of light. Special arrangements may lower its speed even further.

### What is the speed of light per planet?

The speed of light is the same for every observer everywhere. That is a fundamental tenet of the theory of special relativity (and everything based on it, such as the general theory of relativity and quantum field theory). To date no violation of the consistency of the speed of light has been measured. By the way, this does not say the speed of light is the maximum speed, just that the speed of light is… Read More

### What is the speed of sound added with the speed of light?

The speed of light in vacuum added to the speed of sound in dry air at 20 deg C at sea level is 299,792,798 metres per second.

### What whould happend if uneverse expand faster than speed of light?

The Universe actually DOES expand faster than the speed of light.

### Is the speed of light directly proportional to the distance traveled?

Einstein's theory of "special relativity" says that the speed of light is constant across all frames of reference. The speed of light is about 186,000 miles per second, or 300,000 km per second.

### Why speed of any object on earth can not reach the speed of light?

According to the Special Theory of Relativity, this isn't possible. One of the reasons is that it would require an infinite energy to speed up an object to the speed of light - and it would acquire an infinite mass.

### Is it possible for a human to move quicker than the speed of light therefor aging more quickly?

No, a human being cannot travel faster than the speed of light. In fact, according to the Special Theories of Relativity state that it would take an infinite amount of energy to accelerate to light speed, meaning that it is impossible for ANY particle to accelerate to light speed. As for the aging idea, this is just a bit of science fiction. However, the Special laws say nothing about particles constantly moving at light speed… Read More

### Is it true or false the second postulate of special relativity says that the speed of light in empty space depends on the motion of the source or of the observer?

False. The speed of light in empty space is a constant, independent of the motion of the source/observer. An observer travelling towards or away from a light source at 99% the speed of light would measure light going the same speed as an observer stationary relative to the light source.

### How did Albert Einstein determine the speed of light?

Albert Einstein did not determine the speed of light, rather that the speed of light was the maximum speed possible in the universe. The speed of light was discovered in the late 1600's by Danish astronomer Ole Roemer, using Jupiter and its moon Io. It was later used in Maxwell's equations of electromagnetism, and then later used by Albert Einstein in his theory of special relativity.

### Why any object cannot travell with the speed of light?

Some particles, like photons and gravitons, are believed to ALWAYS travel at the speed of light. Particles, or larger amounts of matter, that move at a slower speed can't be made to travel at the speed of light - according to the Special Theory of Relativity, that would require an infinite energy.

### Can a lepton travel faster than the speed of light?

Leptons have mass. According to special relativity, no particle with mass can travel at or faster than the speed of light. It would take infinite energy to do so.

### What is the name of the theory that time slows down when approching the speed of light?

This is part of the Special Theory of Relativity.

### Can man go the speed of light in outer space?

No. Humans cannot travel the speed of light, and do not have the technology to even get close to this speed. According to the Special Theory of Relativity, it would be impossible for anything that has mass (which would include humans) to accelerate to the speed of light. This is because, as an object begins to approach the speed of light, the object's mass begins to increase infinitely. Thus, it will then take even more… Read More

### How much energy would be required to accelerate a 1kg of mass up to the speed of light?

Concerning Albert Einstein's special theory of relativity, no mass can be accelerated to the speed with light: this would acquire an infinitely amount of energy. For the special interested: the European Organisation for Nuclear Research (CERN), recently registered particles (Neutrinos) traveling faster than light. This is rather new research and are being debated and retested per today (2011), and will highly affect modern physics if proven true. UPDATE: per 2012, CERN found a computer error… Read More

### What is the speed that gravity travels?

Gravity is believed to travel at the speed of light. This follows from theory, especially the Special and the General Theory of Relativity; I believe there is not yet enough experimental evidence to confirm this speed.

### Why can nothing be closer than light to the relativity barrier?

Actually there are things that travel at the speed of light other than light itself. According to special relativity all massless particles must travel at the speed of light, so this includes for example gluons, or the particles that supposedly mediate gravity, the gravitons (the 'speed of gravity' is equal to the speed of light). The prime reason why this must be so is that the speed of light must be the same for all… Read More

### Why is the speed of electron beam greater than the light speed in cathode ray oscilloscope?

It isn't. Nothing travels faster than light, especially an electron. If it tried it would become infinitely heavy as it reached the speed of light. You would then need an infinite force to accelerate it further. To know more, Google on "special relativity"

### Why is the speed of light fastest in the universe?

Light is fastest because it is made up of particles called photons which have no mass. To speed up an object, you have to give it energy. The theory of special relativity predicts that to make an object with mass travel at the speed of light would require an infinite amount of energy, which is impossible. Thus, nothing with mass can travel at the speed of light (and, therefore, nothing with mass can travel faster… Read More

### Why can't anything travel at a speed faster than light?

Various reasons, most of them related to the Special Theory of Relativity. 1. To speed something up so that it even reaches the speed of light (from an initial speed that is slower than light) would require infinite energy. (However, this doesn't preclude hypothetical particles that ONLY travel faster than the speed of light.) 2. If it is were possible to travel faster than the speed of light, it would also be possible to travel… Read More

### Why do the mass increase by speed?

when the speed of the object of mass nearly reaches the speed of light , its length will be smaller(the theory of special relativity) , and so its size in space ,which leads to an increasing of mass. the discreasment of length given by : L = L0 / (1 - v2/c2)^(0.5) . where v : the velocity of the object. c : the speed of light .

### Is it the speed of light or light speed?

Is what the speed of light or light speed. ANSWER 300,000 km/s

### What does the theory of special relativity say about the equivalence of different frames of reference?

It says that the speed of light in a vacuum measured in any inertial frame of reference is equivalent to the speed of light in a vacuum measured in any other inertial frame of reference.

### What would happen if you traveled the speed of light?

Nothing in this universe travels with the speed greater than or equal to the speed of light. According to the special theory of relativity, if an object is traveling with the speed of light, length contraction of that object takes place. The length of the object in the direction of the motion will contract, whereas the length perpendicular to the motion will remain unaffected. But just for arguments sake, if you did travel at the… Read More

### If a plane is traveling at the speed of light and turns on its head ligths will the light be even with the plane?

this is a bit complicated but no, although the plane cannot reach the speed of light, even if it did the relative speed of the light is always the speed of light so it will not be even with the plane

### How is it possible for our light horizon to be 40 billion light years away when the universe is only 13.7 billion years old?

That means that this "horizon" is receding faster than the speed of light from us. In Special Relativity, moving faster than the speed of light is not possible, but in general relativity, it is possible under certain circumstances. "Locally", nothing can move faster than the speed of light - in this case, informally, it is "space itself that is expanding".

### Albert Einstein theory of relativity?

E=mc2 is the formula but the theories were called: the general theory of relativity about mass traveling at or faster than the speed of light while accelerating positively or negatively the special theory of relativity about mass traveling at the speed of light while holding a steady speed The formula means: "Energy E equals mass m times the speed of light c squared"

### What travels at 300 000 km per second?

That is the speed of light. That is the speed of light. That is the speed of light. That is the speed of light.

### Why do you age more when you approach the speed of light?

Actually you would age slower. Time passes more slowly at higher speeds. For a detailed explanation (how this result is derived), read an article about the Special Theory of Relativity - however, it is based on the basic assumption that the speed of light is constant. This strange fact - that the speed of light (in a vacuum) is constant - has been confirmed by countless experiments.

### What is light speed relative to?

The speed of light is equal for all observers. This is a postulate of special relativity. Therefore the speed of light is absolute, it is not relative to anything. Because of this you get all the 'strange' effects like time dilatation and length contraction you might have heard of. The speed of light was calculated by James Maxwell in his theory of electromagnetism, but that theory didn't state what the speed was relative to, and… Read More

### Why is the speed of light not higher?

The Speed of Light is considered infinite speed, as no matter can reach the speed of light.

### Is it possible to travel at the speed of light in water?

The speed of light in water is less than the speed of light in space. Only light can travel at the speed of light.

### What is so special about c?

c is the universal speed limit. Nothing can go faster than c unless it has negative mass. c is represented numerically as 3X108. This is the speed of light in a vacuum.

### Why you are not able to reach at the speed of light although there is nothing in physics which stops us from doing this?

If you think that nothing in physics prevents objects having mass from moving at the speed of light, then you are over 100 years out of date on your physics. Special Relativity is the part of physics that prevents this.

### Why does E'm'c2 (Rest energyrest mass x speed of light x speed of light)?

Already we are familiar with kinetic energy = 1/2 m v^2 So with same dimensions we can accept E = m c^2 Here c the velocity of light. This can be derived based on the assumption that mass too would vary as the body speeds up. This is what we call mass variance. OK, Special Relativity is wrong; you've exposed it! Light has mass and it travels at -- the speed of light. So there… Read More

### Why can't you go as fast or faster then the speed of light?

Several reasons, related to the Special Theory of Relativity. 1) If you add two speeds that are less than the speed of light, the result will also be less than the speed of light. For example, a rocket moving at 2/3 the speed of light fires a bullet, which goes at 2/3 the speed of light relative to the rocket; the speed of the bullet relative to Earth would still be less than the speed… Read More

### What mathematical relationship exists between kinetic energy and mass?

Kinetic energy = 0.5 x mass x speed squared. This formula is for the special case that the speed is non-relativistic, i.e., much slower than the speed of light.

### What is the relationship between the velocity of propagation in a t.t.l and the speed of light?

I don't know what a t.t.l is but I do know that the propagation of the speed of light compared to velocity is explained in Einstien's Special Theory of Relativity. It basically states that as an object approaches the speed of light, distance becomes greater, and time slows down (compared to an object at rest). Unfortunately, there is no way to truly tell if you are at rest. Sure you can say that you are… Read More

### What does celeritas mean?

Celeritas means 'at the speed of light'. In Einstein's formula E=MC2, the 'C2' stands for 'the speed of light times the speed of light, or, the speed of light times itself, or, the speed of light squared.