Help!

[Rasine]

i'm new to this forum and the physics world. please don't laugh if inqure about subjects that seem ignorant to you.

what does eveyone think about particals travling faster than light, inwhich the minimum speed is just above the speed of light and the maximum is just below double the speed of light?

[Mean-Hippy]

Well well, I don't know if you are refering to some reasearch in particular but the lightspeed limit for objects travelling in space is really something quite solid. See, as objects gain speed, they gain energy and therefore mass. And of course you need more energy to push a styrofoam ball than a metal ball, so the faster you object goes, the more energy you need to make it accelerate . By the time you reach 99.999999...% of the speed of light, you would need an infinite amount of energy to accelerate your object some more so..... not gona happen. The particles who do travel at light speed can do so because they have no mass, like photons ! ALWAYS be extremely doubtfull of any physics that claims to have figured out faster-than-light-travel. Their are however some theory about attaning that by acting upon the fabric of space itself but so far we dont even know if thats even possible, let alone how...
If you just discovered yourself an interest with physics,let me suggest a few good reads:
Stephen Hawking ( astrophysic ) :
- A brief history of time ( mildly outdated but still good for the basics )
- The Universe in a Nutshell ( their is a beautifull deluxe set with both books illustrated)
Gary Zukav ( quantum physic )
- The dancing Wu Li Master
Brian Greene ( Superstring theory )
- The Elegant Universe ( make sure you get some background before tackilng this one )


Hippy :rofl:

[Gara]

Well there are particals that go faster than light, when light is being slowed down.

I want my PC to give off Cerenkov Radiation. hmmmmmmm blue glow ^_^

[JohnDubYa]

Well, if a particle had imaginary mass and traveled backward in time it could go faster than the speed of light. I have no problem with imaginary mass, but traveling backwards in time is a no no (at least to me).

[Albert's your uncle]

Mean-Hippy, you are right in saying that to get something to speed up from < c you would need infinite energy for anything with mass. It is also true that anything without mass (i.e a photon) cannot travel faster than c. However, what if the particle was already travelling at > c? The maths is quite clear about getting something travelling below c to accelerate to a speed > c, but the maths also works for particles which always travel > c.

I'm not saying that such particles exist - I've never seen one! I'm just saying that 'theoretically' it is possible.

[Nenad]

why can't anything without mass travel faster than c?

[alpha_wolf]

why can't anything without mass travel faster than c?
It's a consequence of special relativity - if a particle has a mass of 0, it must be traveling at exactly the speed of light.

Edit: Sorry for not giving a more detailed answer, but it follows from a mathematical derivation (not too complex), which I do not remember.

[Rasine]

what if there are particals out there that we don't have any knowledge of becuase of the fact that they travle faster than c? what if they always have been, thus not needing to run into the impossibility of accelerating past c?

[pmb_phy]

It's a consequence of special relativity - if a particle has a mass of 0, it must be traveling at exactly the speed of light.

Edit: Sorry for not giving a more detailed answer, but it follows from a mathematical derivation (not too complex), which I do not remember.
It's not really a consequence of SR per se. It can be shown using SR that if a particle moves at speeds >c then there is a problem with causality. Tachyon's (defined as particles for which v > c) don't violate energy conservation if v > c.

Pete