Faster than light

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Faster than light

Why is it not possible to make anything go faster than light?
We first thought going 20km/h was immpossible..then we did go that fast, then it was said that the speed of sound was immpossible, but we can go faster than sound. Maybe we really CAN go faster than light...

You can't conquer the game if you can't conquer yourself.

Jetru

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The other two situations were just the unjustified opinions of a few people, but there exists actual evidence that you can't go faster than the speed of light.

Beer Hunter

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Beer Hunter wrote:The other two situations were just the unjustified opinions of a few people, but there exists actual evidence that you can't go faster than the speed of light.

Not wanting to decry your statement but what/where is the actual evidence that you cannot go faster than the speed of light?

Bugdude
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Actually, the speed of light limit is only in a vacuum, speed of light and faster can be acheived in a medium.

You can't conquer the game if you can't conquer yourself.

Jetru

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There isn't any actual evidence, however special relativity predicts than in order to accelerate to the speed of light, you would need infinite energy. Also, this means only 'massless' particles can travel at the speed of light, otherwise they'd have infinite mass. Testable aspects of the theory have been confirmed with great precision, but it's not strict evidence.
Quantum mechanics has uncovered some more interesting twists wherein things may possibly travel faster than light (for instance, the EPR paradox -- what Einstein called "spooky action at a distance" -- which has now been shown to exist), but the chances of being able to use these phenomenon practically to move objects or information faster than light still looks bleak. (Although there are other cool applications, like quantum cryptography)
Guest

So, why is the energy required infinite? I know about the mass increasing thing, but maybe it IS going faster than light but we just can't comprehend it from our DIMENSION. It seems as if mass is increasing,because momemtum increases(which is actually because of the increase in speed)

And how does light travel anyway. Electro-magnetic fields perpendicualr ...ya ya i know that. How can it just go through nothing like that?

You can't conquer the game if you can't conquer yourself.

Jetru

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This essay is over-generalized and makes some misleading statements, but it may help as an introduction to the concept. You could find a more complete description by searching for Special Relativity (here's the wikipedia article).

Electromagnetism (i.e. light) is a fundamental force of it's own right; like gravity. Current theories (QED) define it as the emission and absorption of photons (particles of light), which are free to travel through empty space just as any particle is.
Guest

Einstein's theories might not have been proven, but they remain consistent with experimental results. This is evidence. I never said we'd "proven" it, but I'm tired of hearing analogies between scientific theories and people's random opinions.

Beer Hunter

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Jetru wrote:Actually, the speed of light limit is only in a vacuum, speed of light and faster can be acheived in a medium.

I believe Snell's Law says that it's the reverse. Light is fastest in a vacuum and is slower in a medium.
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MXP

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Colin Jeanne wrote:
Jetru wrote:Actually, the speed of light limit is only in a vacuum, speed of light and faster can be acheived in a medium.

I believe Snell's Law says that it's the reverse. Light is fastest in a vacuum and is slower in a medium.

I think Jetru got this one right. The speed limit is the speed of light in vacuum, c. In a medium in which light travels slower, a particle can travel faster than light (but not faster than c).

I work with a bunch of physicists and, speaking about the speed of light, one of them told me that looking at it in a modern way, the speed of light is always c, but the particles in a medium deform time-space around them so light ends up twisting and being scattered when it passes near a particle. The net result is that light seems to travel slower, but actually it's just taking a longer path. The other consequence of this is that a ray going through that medium will scatter and disperse. For instance, if you launch a laser through air and point at a wall one mile away, you are not going to get a little dot of concentrated energy any more, but more like a blurred circle.

Alvaro
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Okey, c = fastest. Heat = particles "moving/shaking". Can you then say that when atoms are moving in the speed of light, c, thats the hottest anything can get?

-273,15 °C is when they're not moving at all.

Safari

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Safari wrote:Okey, c = fastest. Heat = particles "moving/shaking". Can you then say that when atoms are moving in the speed of light, c, thats the hottest anything can get?

-273,15 °C is when they're not moving at all.

No, there is no 'hottest' (as far as we know). What prevents things going faster than light, and arises from special relativity (and has incidentally been observed a lot in particle physics experiments, if you believe that sort of thing) is that when you accelerate something, it becomes heavier. Thus, by inertia, the next time you want it to accelerate, putting the same amount of impulse (impulse = force x time) will give you a smaller increase in speed.

This is very closely linked to E = mc^2, which you must have heard of. It's basically saying that when you make something go faster, you increase its kinetic energy. An increase in energy is equivalent to an increase in mass.

As an aside, special relativity is founded on the assumption that c (speed of light in a vacuum) is equal in all inertial reference frames. Once you've made that assumption, it's easy to work out for yourself. No calculus required! The reason people believe this to be true is that assuming c is the maximum speed leads to all kinds of interesting consequences, all of which (so far) appear to occur in reality.

GeekDog

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Alvaro wrote:
Colin Jeanne wrote:
Jetru wrote:Actually, the speed of light limit is only in a vacuum, speed of light and faster can be acheived in a medium.

I believe Snell's Law says that it's the reverse. Light is fastest in a vacuum and is slower in a medium.

I think Jetru got this one right. The speed limit is the speed of light in vacuum, c. In a medium in which light travels slower, a particle can travel faster than light (but not faster than c).

I see. I misinterpreted the question to mean that light will travel faster in a medium than in a vacuum.

I work with a bunch of physicists and, speaking about the speed of light, one of them told me that looking at it in a modern way, the speed of light is always c, but the particles in a medium deform time-space around them so light ends up twisting and being scattered when it passes near a particle. The net result is that light seems to travel slower, but actually it's just taking a longer path. The other consequence of this is that a ray going through that medium will scatter and disperse. For instance, if you launch a laser through air and point at a wall one mile away, you are not going to get a little dot of concentrated energy any more, but more like a blurred circle.

If you dont mind my asking, do you write programs for these physicists? What kind of programming do you do?
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MXP

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Colin Jeanne wrote:If you dont mind my asking, do you write programs for these physicists? What kind of programming do you do?

Errr, not exactly. These physicists and I (and astronomers, and experts in speech recognition...) write programs to model financial markets and invest in them automatically. I work for a hedge fund that uses quantitative methods.

Alvaro
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Alvaro wrote:Errr, not exactly. These physicists and I (and astronomers, and experts in speech recognition...) write programs to model financial markets and invest in them automatically. I work for a hedge fund that uses quantitative methods.

I'm somewhat curious. How do the other people factor in to how you make investments? Are there certain patterns in nature (i.e. celestials movements as studied by the astronomers) that correlate to market fluctuations, and that's how you base predictions, or what? I can see the usefulness of a mathematician like yourself, but I'm curious as to what speech recognition experts can do to help. Don't take this the wrong way, I don't mean any disrespect to any of your colleagues.
"Given enough time, man can do anything with a bit of string and some Tinker toys." Bruce Bolden, Senior Instructor at the University of Idaho.

leas5040

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