Why not faster than light?

absolutezero · Jun 1, 2005

Ok, so regardless the material light is going through, the speed will remain constant... but does the speed slow down? Instead of traveling at 186,000 mps, does it say drop down to 100,000 miles per second? just a rough number, but that is what I am wondering? Thanks!

yevaud · Jun 1, 2005

Yes. Interference with the medium reduces it. Light travelling through water can have a velocity as low as 40% or less of that of light in a vacuum. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

spacechump · Jun 1, 2005

From a classical standpoint yes Yevaud. But not from a QED standpoint.

yevaud · Jun 1, 2005

Yes, well remember it's an averaging effect. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

Saiph · Jun 1, 2005

temperature has no direct effect on the speed of light. However, temperature does affect the medium in which light travels, and by altering the medium, the speed is altered. How it is altered depends on the medium. And there are two ways of looking at light traveling through a medium. As a wave, it travels slower, as the two constants that govern it's speed no longer have the value they hold in vacuum. The presence of atoms around them, shift the value of the constants (permeability and permisivity IIRC), and thus affect the speed of light. In the photon sense, each photon travels at the SOL in a vacuum. However, it is absorbed, and re-emitted enroute, which causes delays and interference. The net effect is slower light. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

spacechump · Jun 1, 2005

"Yes, well remember it's an averaging effect." That's true.

petepan · Jun 2, 2005

Sorry iv'e come in a little late, but i had a thought about this statement ... As it's mass increases, it effects the continuum around it more and more .. Could this be some sort of '(space/time) frame dragging' effect? Just a thought....

spaceinvador_old · Jun 2, 2005

Yes it should be possible to exceed the speed of light. I think if there was a "Big Bang", it could have propelled out debree faster. Infact we wouldn't see that debree cause it went passed light speed.

yevaud · Jun 2, 2005

Pete, in part, that's exactly what it is. Remember how godawful strong the gravity is approaching the event horizon. The spacetime metric is compressed, there is frame-dragging, and (depending on the size, eg mass) intense tidal effects. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

Saiph · Jun 2, 2005

Spaceinvador: You can exceed the speed of light, sorta. You cannot go "through" space at a higher speed. I cannot move from this location, to that location at a speed higher than C. I can, however, have space change at a higher rate. Space can expand or contract, or move however it wishes, at speeds higher than C. So if I can figure out a way to make that location come closer to this location...I can do so at speeds higher than C. It is a very non-traditional way of moving, as we can only move through space at this point. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

siarad · Jun 3, 2005

<blockquote>In reply to:<hr />So if I can figure out a way to make that location come closer to this location...I can do so at speeds higher than C. It is a very non-traditional way of moving, as we can only move through space at this point. <hr /></blockquote> Seems you're a Star Trek fan. The Space Warp drive moved space to them getting over the problem of crushing g force on the crew.

grooble · Jun 3, 2005

I'd ask all of you this - In the last 200 years we basically went from horse and cart to hypersonic flight, moon landings, and a probe almost out of the solar system. Who knows what we will acheive in 200 more? probably the better part of the speed of light. Do you honestly believe that given 100s of years we won't be able to crack light speed or find a way around it? What about 1000s, 10,000s of years?

absolutezero · Jun 9, 2005

Do you honestly believe that given 100s of years we won't be able to crack light speed or find a way around it? What about 1000s, 10,000s of years? Grooble, makes an excellent point and it comes back to my original first post. I agree with him on the fact given another hundred years or so, we could possibly get around this! I mean, I know there is "no way around this", but again, at a time, all the scientist thought the world was flat, that life was on Mars, all these other theories that were thought to be correct but weren't. So I guess, I feel its possible we can do it.

absolutezero · Jun 10, 2005

Yes it should be possible to exceed the speed of light. I think if there was a "Big Bang", it could have propelled out debree faster. Infact we wouldn't see that debree cause it went passed light speed. SpaceInvador made this comment. Is there in validity to this? Second question, this is kinda off subject but a photon. As electrons have quarks, quarks...maybe have strings. Do photons go down to smaller particles that we know of?

nacnud · Jun 10, 2005

As far as we know a photon is just energy, there are no bits it can be broken down to. There is no validity in FTL.

R1 · Jul 9, 2005

well this is something else. Reading todays Scientific American I see others do agree that when the observable universe as we see it today was the size of a grapefruit, it expanded faster than the speed of light. Does the next sequence of knowledge have stuff accelerating? In other words, the universe started to expand faster than the speed of light AND we are even in a universe of accelerating expansion? and can time travel to the past be possible at superluminal speeds? <div class="Discussion_UserSignature"> </div>

raghara2 · Jul 10, 2005

"i was also amused by your argument about infinity being a number, if u try to use infinity in an equation surly the equation becomes useless as the equation will always equal infintiy which can not be defined. I totally agree with najaB that you can not use infinity as you would use a number as in my opinion it is more a statement. " That's incorect. define inf = 1/0 0 * inf = 1 Obviously it's not about imposibility, it's rather about creativity. Note teachers are often lying you, or simplifying things to avoid questions on what they don't know correct answers. BTW this isn't chat.

raghara2 · Jul 10, 2005

When you'd like to try to talk about FTL then don't use photons. They are known to travel at perceived speed of c. You might more like to use Lorentz relativity.

Saiph · Jul 10, 2005

actually 0*inf = 0. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

raghara2 · Jul 11, 2005

It depends on what type of Math are you using, and who would you ask. However because I used define... it equals 1 by definition.

mrmorris · Jul 11, 2005

"One might hope this is possible, but as the laws of the universe forbid it, then it's highly unlikely." The answer then is obvious. We should stop having physicists look into ways to go faster than light. The people we really need working on it are lawyers specializing in criminal or tax cases. They can find loopholes in any law. It's about time we found a use for the slimey buggers.

Saiph · Jul 11, 2005

steve, objects with a redshift of 1.5 or greater are receeding at superluminal velocities. http://tinyurl.com/98chu <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

R1 · Jul 11, 2005

Saiph thanks for the article, it's very interesting I thought that there really is stuff out there traveling superluminally superluminal motion outside of local reality should merit interest at the very least because travel to the past may just be possible <div class="Discussion_UserSignature"> </div>

Saiph · Jul 11, 2005

You can travel to the past...if you can out race a light beam (via special relativity). However, even the galaxies moving superluminally via cosmic expansion don't do this, as they do not move through space to achieve those speeds. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

R1 · Jul 11, 2005

interesting then speeds above C are not reachable, unless you can control inflation and even though we cant travel faster than C on earth, I guess its interesting, the stuff traveling around 1.5 C just outside our local reality, I didnt realize we have already observed around 1000 objects to be traveling about 1.5 lightspeed ! and I didnt realize speeds about 50 times C are how fast the fastest stuff was receding(I guess in the seconds and minutes before matter formed), though now I'm beginning to think I guess if inflation is constantly accelerating, then I guess stuff about 300 million Gigalightyears away could possibly be traveling away from us at thousands of times faster than lightspeed by now. where the heck is everything supposed to be going in such a hurry just kidding, on this sentence. <div class="Discussion_UserSignature"> </div>

Why not faster than light?

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