Shoutbox

i think its a about speed mainly,

for example, your on a train, you see the scenery woosh past, you think your going fast, but related to the spinning of the globe your not..

this is me trying to sound clever, i read this somwhere i think its wrong but you get the idea...

After reading some,

I believe the theory is, that when say you travel with in a car that's going 50 mph, another car passes also going 50 mph, it seems that the car is going 100mph. BUT when going almost the speed of light this is not the case...

Say you travel in your spaceship with 0.99 the speed of light and another spaceship passes also going 0.99, it still looks like it's going 0.99

Then what was what I said before?

There are two theories of relativity: special and general. I doubt you want the general one explained because it is vastly complicated and reserved for PhD level research only. There are two parts to the special theory of relativity:
1. That, in a vacuum, the speed of light is constant no matter your frame of reference, the inertia of the observers or the velocity of the object emitting the light. (c)
2. Basically that the laws of physics do not depend on the state of inertial motion.

The theory is basically E = mc�. That's the widely known usage, to be physically correct it is: (delta)E = c�(delta)m. The change in energy is equal to the speed of light squared multiplied by the change in mass.

That's the fundamental, underlying stuff about it. That was basically me reciting what I remembered from my uni textbook. Heh.

Of course the effects of this theory are more widely known, i.e. the faster you travel the slower time goes, so if you travel really fast you age slower.

A small expansion to tantalise everyone:
Theoretically, purely as a mathematical construct, one thing can travel faster than the speed of light.
Imagine you have a donkey equidistant from two bales of hay that are exactly the same, EXACTLY the same... which bale does the donkey choose?
That's the analogy, and it forms a perfect symmetry. When that symmetry is broken (where such a symmetry exists) a particle called a tachyon is created and emitted, which travels faster than light.

technicly you wouldn't see the other spaceship, it passes by too fast

but y is it the 50+50=100 and 0.99+0.99=0.99?

quote:

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Originally posted by Supersonicdarky
but y is it the 50+50=100 and 0.99+0.99=0.99?

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That's not completely true.
I said 50 mph and .99 speed of light.

And what Time said can be read at wikipedia, but we wanted it explained for the people that don't understand that

And other thing: Some scientist managed to slow down light to 17 meters per second, and also stop it momentarily

quote:

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Originally posted by Ezra
And other thing: Some scientist managed to slow down light to 17 meters per second, and also stop it momentarily

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link to source?

quote:

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Originally posted by Ezra
And other thing: Some scientist managed to slow down light to 17 meters per second, and also stop it momentaraly

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Which is why we say that c is the speed of light in a vacuum. It's ever so slightly slower in normal air than it is in a vacuum (but so inperceptibly so that we can just use c in most of our calculations...).

quote:

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Originally posted by Ezra
And what Time said can be read at wikipedia, but we wanted it explained for the people that don't understand that

And other thing: Some scientist managed to slow down light to 17 meters per second, and also stop it momentarily

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Yes, it can be. Though I remember it all from Contemporary Physics classes. That was written from memory, hence all my edits.
Light travels at different speeds in different media, i.e. it travels slower in water, slower in glass... c is only its speed in a vacuum.

quote:

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Originally posted by MoRiA
Which is why we say that c is the speed of light in a vacuum. It's ever so slightly slower in normal air than it is in a vacuum (but so inperceptibly so that we can just use c in most of our calculations...).

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Yeah I know that , I just thought It was pretty clever (That's also why light slows down 30% in a fiber optic cable)

About that thing with the spaceships:

quote:

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Originally posted by wikipedia
if two cars approach each other from opposite directions, each travelling at a speed of 50 kilometres per hour (31 miles per hour), one expects that each car will perceive the other as approaching at a combined speed of 50 + 50 = 100 km/h (62 mph) to a very high degree of accuracy.

At velocities at or approaching the speed of light, however, it becomes clear from experimental results that this rule does not apply. Two spaceships approaching each other, each travelling at 90% the speed of light relative to some third observer between them, do not perceive each other as approaching at 90% + 90% = 180% the speed of light; instead they each perceive the other as approaching at slightly less than 99.5% the speed of light.

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Source: http://en.wikipedia.org/wiki/Speed_of_light

Not that we would see the spaceship, because our eyes don't even capture images that fast.