Scientists Mess with the Speed of Light (breaking the speed limit, sort of)

pure energy systems ^ | 19 aug 05 | Ker Than

[Drammach]

Somebody 'splain to me where this 'misconception' is, because I was pretty sure that one of Einstein's laws is exactly that.

While Einstein says that Light can't surpass C, nor can any mass, it does not address relative speeds..( I think )

You have a line, A,B,C..
A "particle" travels from A to B at light speed...
Another "particle" travels from C to B at light speed..
Both particles are traveling at light speed in relation to B...
A and C are travelling relative to each other at Twice the speed of light..

Are you thouroughly confused now?
I am..

[Drammach]

Once you get past the speed of light, the equations work again, except that a number of them have an imaginary component (sqrt-1).

That sounds much better than what I remembered reading about in the mid-70's..
About all I could remember was that it was theorized there were particles that travelled faster than light and that relativity made it "practically" impossible to slow to that limit..

[Izzy Dunne]

You have a line, A,B,C..
A "particle" travels from A to B at light speed...
Another "particle" travels from C to B at light speed..
Both particles are traveling at light speed in relation to B...
A and C are travelling relative to each other at Twice the speed of light..

Sorry, but that's not the case - Einstein addressed that:
It turns out that when you ADD two velocities, you are using an approximation that works fine at "normal" speeds (two cars at 50 MPH, say), but it fails at near light speeds.

The real equation is NOT V = V1 + V2, but this:

v = (v1 + v2) / (1 + v1*v2/c^2)

If you work that out (with c = speed of light), you'll find that even if V1 = 100,000 MSP, and V2 = 100,000 MPS, they are traveling relative to each other at 155,258 MSP.

Try it again, with V1 = 180,000 MPS and V2 = 180,000 MPS (0.96c). Surely that exceeds the speed of light, right? Nope. Relative to each other, they are traveling at 186172 MPS.

You can't get there from here.

[Drammach]

Thanks for your explanation..

I am no mathematician, so I will have to take your word for it..

I will look into this some more and attempt to understand it a little better..
I avoided using "v" instead of "c" because I assumed that there would not be a "slower" speed for the observation of relative space from the 2 moving objects..

I will have to research this and learn more..

[Izzy Dunne]

If you Google EINSTEIN VELOCITY you will find several explanations.

[Drawsing]

Speeding up the speed of light? Hah! This is easy. Everytime I go 70 miles per hour down the highway and turn on my headlights, then that light is going the speed of light plus 70 miles per hour!... :)

[Drammach]

Thanks..

[Sensei Ern]

If going the speed of light stops time, then if I can slow light down, will that make it easier to time travel? If we slow light by 75% and I can go twice that, will that mean I can go back in time?

I may be old fashioned and like the priests who persecuted Galileo, but until it is proven, I refuse to accept time tripping as anything but science fiction.

[Shalom Israel]

I'm having trouble with this. For one, what if the light is all one frequency, as in a laser? For two, doesn't incoherent light all travel at C?

Not a physicist, but I'll have a crack at that. If you've ever tuned a guitar, you'll have noticed that when a string is almost in tune, the sound appears to "ripple". That's the two nearby sound frequencies combining to produce an apparent third wave as the two sometimes add to each other, and sometimes cancel.

From the article, it sounds like they're doing something similar with light, where the "pseudo" wave produced by interference actually propagates faster than the light itself.

[IronJack]

the "pseudo" wave produced by interference actually propagates faster than the light itself.

How? I can see some sort of a harmonic being generated, but I can't fathom how it would actually travel faster than the light that generated it. To use your example, it would be like the harmonic being propagated at greater than the speed of sound, simpy because it's a harmonic ...

You might be right, but it makes no sense to me.

[SunkenCiv]

from 2005

[Calvin Locke]

Until then, it's just gloried parlor tricks.

Oh yeah? Just wait until they start assigning a light frequency class to ip addresses.

When your internet slows down, then you got to upgrade your service plan...

[19th LA Inf]

information can be channeled through fiber optics at the speed of light

OK, but the "speed of light" in a fiber optic filament is not 186K miles per second as it is in a vacuum, but is reduced in proportion to the refractive index of the glass. I was embarrassed back when I was a mechanical engineer working on an electro-optics design layout and had to have this explained to me by a physicist - - something I had known when I was 12 years old and had forgotten. The neat illustration in the old 1912 encyclopedia at home was based on a formation of troops approaching a plowed field. Their marching speed slowed down when they hit the rough, so the whole formation had to change its direction to keep in step. Refraction explained!