Is the speed of light the fastest speed possible?

[anglepose]

arkain

"Ive heard there was recent observations that detected matter from the earliest point in the big bang era. It was said the matter was expanding at 12x the speed of light..

It almost sounds like a bunch of hooey but I assure you this was from a reviewed scientific study. I'd have to look into it again. sry.."

This contradicts the law that it would take infinte amounts of energy for an item of mass to reach the speed of light.

 

So can you go faster than the speed of light?

[InfiniteNow]

Monty Python: The Meaning of Life - Galaxy Song

Just remember that you're standing on a planet that's evolving

And revolving at nine hundred miles an hour,

That's orbiting at nineteen miles a second, so it's reckoned,

A sun that is the source of all our power.

The sun and you and me and all the stars that we can see

Are moving at a million miles a day

In an outer spiral arm, at forty thousand miles an hour,

Of the galaxy we call the 'Milky Way'.

Our galaxy itself contains a hundred billion stars.

It's a hundred thousand light years side to side.

It bulges in the middle, sixteen thousand light years thick,

But out by us, it's just three thousand light years wide.

We're thirty thousand light years from galactic central point.

We go 'round every two hundred million years,

And our galaxy is only one of millions of billions

In this amazing and expanding universe.

 

The universe itself keeps on expanding and expanding

In all of the directions it can whizz

As fast as it can go, at the speed of light, you know,

Twelve million miles a minute, and that's the fastest speed there is.

So remember, when you're feeling very small and insecure,

How amazingly unlikely is your birth,

And pray that there's intelligent life somewhere up in space,

'Cause there's bugger all down here on Earth.

[Jay-qu]

no you cant. but some things can (thought they do not exceed c) do a search on cherenkov light, there is a thread on it somewhere, or at least its discussed in some thread..

[Pyrotex]

...do a search on cherenkov light, ...

You would have to bring up Cherenkov light, or as it was originally called, Bremmstrallung, which is German for "braking radiation". As it was taught in college in the 70's, a particle traveling very close to the speed of light © could enter a material, such as glass or a crystal, where the LOCAL speed of light (cL) was less than the speed of the particle.

 

cL, it turns out, is a function of the Index of Refraction (Ir) of a material. So, cL in glass = c/(Ir of glass).

 

The particle finds itself in violation of local speed laws! (And this is where everything gets hazy) The particle then "brakes" down to a speed just under cL, by giving off photons--Cherenkov light. But this leaves big questions. How far does the particle enter the material before it "knows" the cL has dropped? Does the particle actually travel at speeds > cL for some tiny distance before its Cherenkov light brakes it to a lower speed? Is this even possible to conjecture? HOW does the particle know what cL is? And on and on and on...:hihi:

[InfiniteNow]

show off. :hihi:

[Pyrotex]

show off. :eek:

I can't help it!

Somebody stop me before I lecture on physics again!!!! :hihi: :cup:

 

BTW...Kudos on Python reference!!

[Qfwfq]

I see that you aren't a particle physicist, Pyro! :eek2:

 

The particle finds itself in violation of local speed laws! (And this is where everything gets hazy) The particle then "brakes" down to a speed just under cL, by giving off photons--Cherenkov light. But this leaves big questions. How far does the particle enter the material before it "knows" the cL has dropped? Does the particle actually travel at speeds > cL for some tiny distance before its Cherenkov light brakes it to a lower speed? Is this even possible to conjecture? HOW does the particle know what cL is? And on and on and on...:)

:)

We particle physicists :) don't consider it a problem with SR at all. Never forget: It isn't c that's the speed of light, it's the speed of light that's c. In vacuo that is. The fact that propagation is slower than c in a material medium doesn't have any bearing at all on the geometry of space-time.

 

Also, Cherenkov light isn't really the same thing as bremstrahlung radiation. A high energy particle can well maintain velocity for quite a while through a material, energy loss can be very gradual. The beam is often passed through layers of material before being used, further to the thin walls of the pillboxes that actually accelerate the particles and maintain their velocity compensating for the loss by synchrotron raditation.

 

See also: "Before starting the description of the Cherenkov effect it must be emphasized that the Cherenkov radiation is entirely unrelated to the bremsstrahlung, which is emitted by the moving electron itself when it collides with atoms in the medium. The Cherenkov effect involves radiation emitted by the medium under the action of the field of the particle moving in it. The distinction between the two types of radiation appears with particular clarity when the particle has a very large mass: bremsstrahlung disappears, but the Cherenkov radiation is unaffected." for instance, from:

 

http://www.gae.ucm.es/~emma/tesina/node4.html

[Qfwfq]

So can you go faster than the speed of light?

There have already been several threads on the matter:

 

http://hypography.com/forums/search.php?searchid=55547

[Pyrotex]

I see that you aren't a particle physicist, Pyro! ...We particle physicists :eek2: don't consider it a problem with SR at all. Never forget: It isn't c that's the speed of light, it's the speed of light that's c. In vacuo that is. The fact that propagation is slower than c in a material medium doesn't have any bearing at all on the geometry of space-time. Also, Cherenkov light isn't really the same thing as bremstrahlung radiation. ...The beam is often passed through layers of material before being used, further to the thin walls of the pillboxes ...

Ahhhh, Qfwfq. How do you pronounce that, by the way? I see you aren't a professor of Medieval French poetry. :)

 

I stand corrected and am delighted to do so. The distinction that c is the speed of light in vacuo cleared up all my questions about Bremstrahlung most effectively. Thank you! And I was unaware that Ch. and Br. were independent phenomena.

 

However, the sentences that begin, "The beam is often..." is completely indecipherable to me. What were you trying to say there? :)

[Tormod]

There have already been several threads on the matter:

 

http://hypography.com/forums/search.php?searchid=55547

 

This way of linking to searches doesn't work as it is a cached search with a timeout.

[Qfwfq]

This way of linking to searches doesn't work as it is a cached search with a timeout.

Ooops! So many things one can learn...

 

http://hypography.com/forums/physics-mathematics/1937-can-something-move-faster-than-light.html

http://hypography.com/forums/physics-mathematics/4425-moving-faster-than-speed-light.html

http://hypography.com/forums/physics-mathematics/3778-particles-can-travel-faster-than-light.html

http://hypography.com/forums/physics-mathematics/1836-faster-than-speed-light.html

http://hypography.com/forums/physics-mathematics/532-faster-than-speed-light.html

http://hypography.com/forums/physics-mathematics/299-faster-than-light-travel-2.html

http://hypography.com/forums/astronomy-cosmology/235-faster-than-speed-light.html

[D3x]

Aren't blackholes pulling matter at speeds greater than c ?!

[Jay-qu]

nope, close to, but not reaching let alone exceeding c.

[Pyrotex]

As I have said before [sigh] Special Relativity (SR) is a description of what the observer observes. Einstein's genius was (partially) in his realization that we do NOT and CAN NOT ever, ever, ever know what is ACTUALLY "going on" anywhere in the Universe outside our immediate frame of reference, right NOW.

 

That was a big sentence. Read it again.

 

All we can do, Einstein understood, is ... observe whatever it is that we observe. That's it. Well, PLUS, we CAN calculate what we should be able to observe.

 

SR is a calculation of what we should (and in fact DO) observe when objects are traveling near the speed of light. But we cannot come to conclusions about objects or events that we cannot observe.

 

By "cannot observe", I don't mean because the closet door is closed. I mean because the object or event is so far away, going so fast, in a strong enough gravity field, or some combo of these, that the light from that object or event can never reach us.

 

Einstein never "proved" that no objects can exceed the speed of light. Oddly enough, he assumed it as a given. Then he built his SR on top of that assumption. The fact that his SR actually gives the observed results is rather spooky to some folks, and is accepted by others as indirect proof that his assumption was correct.

[hallenrm]

This way of linking to searches doesn't work as it is a cached search with a timeout.

 

That's indeed wonderful administration, Tormod. :):

 

BTW, I have a suggestion, can't we have an alphabetical directory of emoticons? :D

[LJP07]

Anyway, why is the Speed of Light the fastest thing possible, what convinced scientists that this observation is true and why can't you get any faster?

[ronthepon]

From what I know, it's the relativistic mass-velocity relation.

 

[math]m = \frac{m_{rest}}{\sqrt{1 - {\frac{v}{c}}}}[/math]

 

As v gets closer to c, te mass of the particle keeps increasing. If the velocity of the particle (v) would reach the speed of light © at any point of time, it's mass and thus kinetic energy would be infinite.

 

Since you cant have any particle having infinite energy, you cant have a particle at the speed of light.

 

Consider it in a way that as you keep applying force to the particle it keeps getting heavier and heavier, and the acceleration gets smaller and smaller with a constant force.

 

Eventually, the observation that confirms the deal is that the momenta(is that the correct usage of plural) of electrons have been found to increase with increase in their velocity. This ain't the best proof, but it's all I know. Try googling to find out the reasons why cyclotrons are not used to accelerate electrons.