# Spd. of light

1. Jul 6, 2009

### tomfr62

When or if an object exceeds the speed of light what will the reaction be a) in our atmosphere, b) in space?
Tom F

2. Jul 6, 2009

3. Jul 6, 2009

### HallsofIvy

Since it is not possible for an object to move faster than the speed of light, relative to any frame of reference, your question is moot.

4. Jul 6, 2009

### tomfr62

Pupil
Thank you, I am aware that nothing can travel faster than the speed of light, I am just curious as to what would be the result if an object could exceed that speed.
Thank you
Tom F

5. Jul 6, 2009

### jobyts

Since the OP's question is answered, I'll use this thread for a related question.

If the speed of light in a different medium is c', is c' the maximum attainable speed for any object in that medium? I do not think so, but I would like to confirm it.

6. Jul 6, 2009

### nasu

No, if the speed of light in a medium is c' (where c' is less than the speed of light in vacuum) an object cam move faster than c'.
The phenomenon is not uncommon for elementary particle and is used to build detectors.
When the particle moves faster than c' there is a "flash" of light that can be observed - Cerenkov effect.

7. Jul 6, 2009

### SmashtheVan

8. Jul 7, 2009

Staff Emeritus
It's a little like asking what's north of the north pole.

In a medium, the answer is given: you get Cerenkov radiation for charged particles. In a vacuum, there is no answer.

9. Jul 7, 2009

### Byllie

It is physically possible to travel faster than the speed of light by invoking general relativity, that is by either warping or ripping space-time. Think about it if we rip or warp space time so that an object is closer to us, it's gonna take us a shorter amount of time to reach it, and therefore we're gonna travel faster than light (if we want to). Similarly the shortest distance between two points is a worm hole rather than a straight line, so it is possible to travel faster than light this way aswell. However both these methods require elusive negative energy of which I know very little about, and is way beyond anything we can achieve in the foreseeable future. With regards to travelling through space faster than light, its handy to look at the highly theological Alcubierre drive (he dreamt it up via star trek) which uses negative energy rather than postive energy to power the body, as opposed to the positive energy used today to travel at lower than speed of light speeds. What you would effectively see, travelling faster than the speed of light according to Alcubierre is this "In front of the ship, stars would become long lines, streaks. At the back, nothing would be seen as light from previous stars wouldn't be travelling fast enough to keep up". Basically like the millenium falcon out of star wars.

How true that is I don't know, just out of this Kaku book i've been reading

10. Jul 7, 2009

### Pupil

None of these sound like faster-than-light travel: they sound like finding-shortcut travel.

11. Jul 7, 2009

### Byllie

But even so, if you can get from A to B faster than light, is that not faster than light travel?

12. Jul 7, 2009

### Pupil

Are you talking about velocity or speed?

13. Jul 7, 2009

### Byllie

velocity, I am speaking in speed due to the common phrase 'speed of light'. I can see how those methods may not seem conventionally 'hyperspeed' like, infact space needs to be pre-ripped in order for faster than light travel to take place (bit like a pre-exsisting highway), but then again, this is only relative to light that does not travel through the ripped space, so you would still be travelling slower than light in the warped zone. So as I said, not faster-than-light travel in the conventional sense.

Take a look for yourself pupil

http://dsc.discovery.com/news/2008/07/28/warp-speed-engine.html

Last edited: Jul 7, 2009