Discussion
bluespanner said:
no because the light would travel at your speed, plus the speed of light. 
Afraid not. You lights would become 'bluer' as it approached the speed of lights because they apparent shortening of light waves. The speed of light would remain constant but time would change. So if you did a quick loop round a few suns which took you, say 5 years it would be many years to those back on earth. The only constant in the universe is the speed of light, time is not constant, time is relative.
srebbe64 said:
Smartie said:
what about if your reversing lights were on too? 
Then these would appear to be going red as the apparent light waves increased. Anyway, why would the revering lights be on if the car was going forward?
thought we'd established that this 'vehicle' was using Lucas electrics!
fidgits is right, light can't travel any faster than the speed of light so you can't just add on source speed. Think of a super-sonic jet - it can fly past with no sound then you get hit by the sound afterwards. By the logic of adding in source speed the sound waves would be travelling at speed of sound + source speed, which they obviously don't as the jet can fly past you in front of its' sound. Sound travels at the speed of sound, light travels at the speed of light.
If you travelled faster than light, you would physically be in one place but your image would be behind you as light has a finite speed. At t=0 the bulb and the light particles are at the same point in space, at t=1 they will both have travelled 1 x c metres and again be in the same place. There is no force to accelerate the light away from the source. Therefore the headlights will work in the sense that the bulb will emit, but they will be useless as they won't be able to light the area in front of ou before you get there.
If you travelled faster than light, you would physically be in one place but your image would be behind you as light has a finite speed. At t=0 the bulb and the light particles are at the same point in space, at t=1 they will both have travelled 1 x c metres and again be in the same place. There is no force to accelerate the light away from the source. Therefore the headlights will work in the sense that the bulb will emit, but they will be useless as they won't be able to light the area in front of ou before you get there.
Gazboy said:
simpo two said:
And you can still fire a bullet in Concorde.
(well, you could have done)
(well, you could have done)
But what if you were sat on it's roof and fired? Would the bullet spurt out 100 feet, only to knock your teeth out as you caught it up again...
No as gravity would make it fall. It might take your knackers out, (or more accurately your knackers would take the bullet out) it just depends on how fast it is fired as to how far away it would get.
vrooom said:
Duh! headlight is running at speed of light, so car moving at speed of light, So The headlight will be running a twice of speed of light
So you're saying that light can travel faster than light? And what about the rear lights - does that light stay stationary once emitted?srebbe64 said:
Afraid not. You lights would become 'bluer' as it approached the speed of lights because they apparent shortening of light waves. The speed of light would remain constant but time would change. So if you did a quick loop round a few suns which took you, say 5 years it would be many years to those back on earth. The only constant in the universe is the speed of light, time is not constant, time is relative.
Wouldn't they only appear "bluer" (or rather appear to emit gamma rays) to those observing from the outside?
But, in reality, wouldn't the headlamp itself (let alone the car it's attached to) become infinitely massive when it reaches the speed of light and would therefore require all the energy in the universe to propel it at that speed. Hence, I don't think the scenario's entirely realistic.
(Don't fail me now, schoolyard physics...)
knoxville said:
Nothing can travel faster than the speed of light. Any example you think of that logically seems to prove otherwise can be answered by either:
At close to the speed of light, time slows down
or
At the speed of light you have infinite mass
At close to the speed of light, time slows down
or
At the speed of light you have infinite mass
No, that's just a theory which you cannot prove, only disprove. What tends to happen in science is a theory will appear to have been proven simply because it is the best explanation at the time. At some stage this theory will be disproven and there will be a shift to a new set of rules. If you look back that's how it has happened with all great scientific theories.
Additionally, time does not slow at close to the speed of light. Time only slows relative to an observer who is not travelling as fast. It's called time dilation.
jewhoo said:
The OP was if you could drive that fast
But if you lok at the quote I cunningly included, you will notice I was not replying to the OP, or the OAP, because then I would have included a quote from srebbe. Now if you look at my susequent edit you will notice I have realised you were not talking to me.
Edited by moleamol on Wednesday 11th October 21:36
The speed of light is the same for all observers due to time dilation effects:
If the two blobs represent two people and the green block is a mirror the light clock will tick (light goes to the mirror) and tock (light returns from the mirror) at the same rate. If however one of the people is moving relative to the other then to each of them the light clock will tick and tock at the same rate, however if the staionary person observes the moving light clock it appears to have slowed down relative to their light clock:
This is as far as my understanding goes at the moment, and I can't be arsed to get my head around the whole time dilation thing and how it relates to light speed cortinas, however I feel that this effect is central in understanding what is happening. Basically for the person at or near the speed of light time appears to speed up and for those that are stataionary the person travelling at the speed of light appears to have slowed down, however, because the speed of light is constant for all observers the light would shine out of the headlight for both parties. Although now I've thought about it I'm not so sure.... Any clever people want to pick up the baton from this dribbling biologist?
If the two blobs represent two people and the green block is a mirror the light clock will tick (light goes to the mirror) and tock (light returns from the mirror) at the same rate. If however one of the people is moving relative to the other then to each of them the light clock will tick and tock at the same rate, however if the staionary person observes the moving light clock it appears to have slowed down relative to their light clock:
This is as far as my understanding goes at the moment, and I can't be arsed to get my head around the whole time dilation thing and how it relates to light speed cortinas, however I feel that this effect is central in understanding what is happening. Basically for the person at or near the speed of light time appears to speed up and for those that are stataionary the person travelling at the speed of light appears to have slowed down, however, because the speed of light is constant for all observers the light would shine out of the headlight for both parties. Although now I've thought about it I'm not so sure.... Any clever people want to pick up the baton from this dribbling biologist?
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