Kyle™
Premium Member
pretty sure people have slowed light down. heard about it in a documentary a few months back. shooting light into a cloud of molecules or something. sounded boring so I didn't really research it.
Going the Speed of Light
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Ellis
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.............
Try shining light into...... ummmm ANYTHING
Sorry, I don't want to sound rude... but seriously.
ThePizzaGuy92
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whenever you look at anything, your looking into the past.
Ton
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My philosophy is that an object in this dimension and remain in current form can not go faster. The only option in theory is travel via other dimensions. e.g. Just has you can fold a paper a 2D object is limited by traveling on the paper but if the 2D object can travel in 3D he can skip space and travel relatively faster than light. Still in the 3D dimension you will not go faster. Any way travel like this you will not be able to go back in time, in my philosophy you could skip and take a shortcut in space.
Escher
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lolfailthread.
I'm still waiting on qqwref, stefan or dene to post.
I'm still waiting on qqwref, stefan or dene to post.
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nitrocan
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I'm just wondering one thing. If a photon is affected by a gravitational field, then shouldn't it have mass also?
brunson
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http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/photon_mass.html
I believe Einstein explained the effects of gravity as curvature of space, which would account for it's affect on a massless particle.
A friend told me an interesting way of looking at time dilation.
You may consider your velocity through space and time to be a vector in 4 dimensions with a magnitude of the speed of light. When you're at rest the vector lies along the axis of time, so you are moving through time at the full speed of light. When you begin to move in another dimension, say X, then your vector moves, maintaining the same amplitude, but changing direction. Decomposing the vector into it's component x and t vectors gives you your motion in x and velocity through time.
I believe Einstein explained the effects of gravity as curvature of space, which would account for it's affect on a massless particle.
A friend told me an interesting way of looking at time dilation.
You may consider your velocity through space and time to be a vector in 4 dimensions with a magnitude of the speed of light. When you're at rest the vector lies along the axis of time, so you are moving through time at the full speed of light. When you begin to move in another dimension, say X, then your vector moves, maintaining the same amplitude, but changing direction. Decomposing the vector into it's component x and t vectors gives you your motion in x and velocity through time.
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cheiney
Regular
Is it possible for any form of matter or energy to reach superluminal speed?
Ellis
Veteran
Nah. Maybe you just weren't specific enough. "People have slowed down light"?
What do you mean by that? If you shine light into air it slows down, or water, or a plastic bottle. So yea, when you shine it into a cloud a molecules, it's going to slow down... big whoop.
Johannes91
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+1 Insightful
I'm a noob at physics and that paragraph cleared up some things very well for me. Much clearer than many really long explanations.
brunson
Veteran
There is nothing in SR that prohibits a particle from travelling faster than light (c), only preventing something with mass from travelling *exactly* the speed of light. A particle would have to "skip over" c, making a discontinuous acceleration in order to go from sub light to super light speed, which would violate a ton of physics.
There is, however, nothing to preclude a particle from being created travelling superliminal. These theoretical particles are called tachyons and subluminal particles are called tardyons.
An interesting property of a tachyon is that the would travel faster the less energy they had. The more energy you put into it, the slower it travels, ultimately requiring an infinite amount of energy to slow down to the speed of light.
All this is theoretical, though...
brunson
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I just asked my friend and he says that with the right units and scaling on the axes, the point-distance formula (distance from (x1,y1) to (x2, y2) = sqrt( (x1-x2)^2 - (y1-y2)^2 ) if I remember right) even results in the correct time and length dilation formulae.
Kyle™
Premium Member
If light slows down when it hits everything, please explain how it is getting here from 5 billion light years away through so much space dust and gravitational force. Please. http://www.hno.harvard.edu/gazette/1999/02.18/light.html
edit: directed to ellis.
edit: directed to ellis.
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nitrocan
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(x1,y1) to (x2, y2) = sqrt( (x1-x2)^2 + (y1-y2)^2 )
It's basically the Pythagorean theorem. c = sqrt(a^2 + b^2)
brunson
Veteran
Why don't you go do some reading and educate yourself before trying to nit pick at everything you don't understand.
The speed of light through a medium other than a vacuum is less that than of the speed of light through a vacuum. When light passes from a vacuum to air, it slows down; from air to water, it slows, from air to glass, it slows down. When it goes from glass or water to air, it speeds up; when it goes from air to a vacuum it speeds back up.
The article you link to describes a material that slows down light a lot more than anything else known before. When the light leaves that material it doesn't continue moving through the air at 38 miles an hour, it returns to its normal speed.
vvtopkar
Regular
@Kyle
Sorry to say this, but Brunson is a really brilliant guy that absolutely knows what he is talking about.
On another note, while we are talking about the speed of light:
Imagine a record turntable. In the case of any rotating disk, a point on the inside of the disk travels slower than a point on the edge of the disk. What if the center of a record was traveling at the speed of light, at what rate would the edge of the disk travel at?
Sorry to say this, but Brunson is a really brilliant guy that absolutely knows what he is talking about.
On another note, while we are talking about the speed of light:
Imagine a record turntable. In the case of any rotating disk, a point on the inside of the disk travels slower than a point on the edge of the disk. What if the center of a record was traveling at the speed of light, at what rate would the edge of the disk travel at?
Johannes91
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It wouldn't travel at all because the record would break.
brunson
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Hardly brilliant, just educated. :rolleyes:
vvtopkar
Regular
Would the edge break at the point it reaches the speed of light since the center is still accelerating?
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