Silly speed of light question..

Silly speed of light question..

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Discussion

wayne_uk

Original Poster:

260 posts

236 months

Sunday 24th October 2004
quotequote all
Right,your car is having a nice little trundle along at the speed of light ( trying to keep it car related here.. ) , you turn you lights on..

Does your lights go twice the speed of light,or don't they come on ?,or do they come on,but stay still..ie it the car does 5 mph slower will you see light travelling at 5mph ?


beer...,stop...,now....

DanBoy

4,899 posts

205 months

Sunday 24th October 2004
quotequote all
Or do they come on but you just don't see them!

tvrgit

8,449 posts

214 months

Sunday 24th October 2004
quotequote all
If you are going slightly slower than the speed of light, will you see your own lights catching up in the mirror? Then when you move over to let yourself past, you move over too.... so then...

<splatt> my head just exploded

alexkp

16,482 posts

206 months

Sunday 24th October 2004
quotequote all
The problem here is that you assume you can be travelling at the speed of light.

Einstein says you can't.

However, some theorists hypothesize that it may be possible to travel vast distances across space without contravening Einstein's laws, but that is another question.

thebluemonkey

1,296 posts

202 months

Sunday 24th October 2004
quotequote all
alexkp said:
The problem here is that you assume you can be travelling at the speed of light.

Einstein says you can't.


Might be wrong here but doesn't he actually say that you could never accelerate to that speed because of the mass increase, but you could travel at that speed if you started off at it ?

regmolehusband

3,555 posts

219 months

Sunday 24th October 2004
quotequote all
But light travels at the speed of light so if you could get said car up to 10% of the speed of light would what speed would the light wavefront travel through space at 110% of the speed of light?

Eric????

Maybe the car would be speared by your light beams if you turned them on!

>> Edited by regmolehusband on Sunday 24th October 19:30

wokkadriver

695 posts

204 months

Sunday 24th October 2004
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Ah Ha! You have just hit upon my theory - the speed of dark, the only thing faster than the speed of light, because it is always there first!

groucho

12,134 posts

208 months

Sunday 24th October 2004
quotequote all
Let's say you could travel at warp 1 (star trek here) I don't think you would need headlights.
Speed of light is not possible as for reasons that thebluemonkey explained.
But who knows? light travels at that speed, so why not other things.

Grouch.

David A

3,221 posts

213 months

Sunday 24th October 2004
quotequote all
thebluemonkey said:

alexkp said:
The problem here is that you assume you can be travelling at the speed of light.

Einstein says you can't.



Might be wrong here but doesn't he actually say that you could never accelerate to that speed because of the mass increase, but you could travel at that speed if you started off at it ?


Correct, anyone else watch K-PAX last night????

alexkp

16,482 posts

206 months

Sunday 24th October 2004
quotequote all
thebluemonkey said:

alexkp said:
The problem here is that you assume you can be travelling at the speed of light.

Einstein says you can't.



Might be wrong here but doesn't he actually say that you could never accelerate to that speed because of the mass increase, but you could travel at that speed if you started off at it ?


Well....yes and no. The problem is that to accelerate to the speed of light would require infinite power as you would achieve infinite mass.

However, there are of course particles that travel at the speed of light in a vacuum (and possibly some that travel even faster). The key thing is the vacuum bit. Some particles can travel faster than light in a medium such as water.

When high velocity particles travel faster than the speed of light in a medium they create a blue flash. This is called Cerenkov Radiation and it can be detected.

To go back to the original question about headlights at the speed of light - if you could achieve it, you would still see the light as you hadn't exceeded the SoL. If you exceeded it you would leave your light behind - however, physics becomes very weird at these kind of extremes, so time would be dilating also, and you would be creating a very strong gravitational field which can actually bend light.

So it's all rather complicated. LOL.

will_t

821 posts

204 months

Sunday 24th October 2004
quotequote all
thebluemonkey said:



alexkp said:
The problem here is that you assume you can be travelling at the speed of light.

Einstein says you can't.





Might be wrong here but doesn't he actually say that you could never accelerate to that speed because of the mass increase, but you could travel at that speed if you started off at it ?




I'm from K PAX and you'r dead right.

Will

Aaargh beaten by 2 mins ..........must type at the speed of light next time.

>> Edited by will_t on Sunday 24th October 19:40

>> Edited by will_t on Sunday 24th October 19:42

ThatPhilBrettGuy

11,804 posts

202 months

Sunday 24th October 2004
quotequote all
Let's not get into the theory of relativity here eh? If we do they'll be all the time slowing down as you go faster stuff, and you'll all wish you've never started it.

turbobloke

92,156 posts

222 months

Sunday 24th October 2004
quotequote all
thebluemonkey said:
Might be wrong here but doesn't he actually say that you could never accelerate to that speed because of the mass increase, but you could travel at that speed if you started off at it ?
Yep, and he'll also let you travel faster than the speed of light, but you'll never be able to slow down and cross through the light speed barrier the other way. It's a 100% effective cosmic no through zone

imperialism2024

1,596 posts

218 months

Sunday 24th October 2004
quotequote all
alexkp said:

thebluemonkey said:


alexkp said:
The problem here is that you assume you can be travelling at the speed of light.

Einstein says you can't.




Might be wrong here but doesn't he actually say that you could never accelerate to that speed because of the mass increase, but you could travel at that speed if you started off at it ?



Well....yes and no. The problem is that to accelerate to the speed of light would require infinite power as you would achieve infinite mass.

However, there are of course particles that travel at the speed of light in a vacuum (and possibly some that travel even faster). The key thing is the vacuum bit. Some particles can travel faster than light in a medium such as water.

When high velocity particles travel faster than the speed of light in a medium they create a blue flash. This is called Cerenkov Radiation and it can be detected.

To go back to the original question about headlights at the speed of light - if you could achieve it, you would still see the light as you hadn't exceeded the SoL. If you exceeded it you would leave your light behind - however, physics becomes very weird at these kind of extremes, so time would be dilating also, and you would be creating a very strong gravitational field which can actually bend light.

So it's all rather complicated. LOL.


But what about if you turn on your high beams?

thebluemonkey

1,296 posts

202 months

Sunday 24th October 2004
quotequote all
alexkp said:

The key thing is the vacuum bit.


Is this to do with the constant velocity part of newtons laws ? or alot more complicated than that ?

thru5h

26 posts

196 months

Sunday 24th October 2004
quotequote all
if you travel at or above the speed of sound you can still hear your self talk or talk to the person in the next seat.

scientists always say things are impossible and give you reasons why (remember when the sound barrier couldnt be broken), only for someone a few decades later to do the impossible and prove them wrong, a theory is a theory.

turbobloke

92,156 posts

222 months

Sunday 24th October 2004
quotequote all
Beam me up Scottie

alexkp

16,482 posts

206 months

Sunday 24th October 2004
quotequote all
thru5h said:
if you travel at or above the speed of sound you can still hear your self talk or talk to the person in the next seat.

scientists always say things are impossible and give you reasons why (remember when the sound barrier couldnt be broken), only for someone a few decades later to do the impossible and prove them wrong, a theory is a theory.


There's a big difference: 733mph at sea level vs. 186,000 miles per second in space.

But there are theories as to how you can get around the light barrier without having to break it...

alexkp

16,482 posts

206 months

Sunday 24th October 2004
quotequote all
thebluemonkey said:

alexkp said:

The key thing is the vacuum bit.



Is this to do with the constant velocity part of newtons laws ? or alot more complicated than that ?


This is Einsteinian physics, Newton does not really cover this - apart from any action having an equal and opposite reaction - which does realte to the problem of infinite speed = inifinite energy = infinite mass.

A vacuum means nothing can interfere with a particle/wavicle in either a negative or positive manner.

(BTW there is no such thing as a perfect vacuum)

gh0st

4,693 posts

220 months

Sunday 24th October 2004
quotequote all
groucho said:

Speed of light is not possible as for reasons that thebluemonkey explained.
But who knows? light travels at that speed, so why not other things.

Grouch.


Because a photon has no mass therefore does not need infinate energy to achieve the speed of light.