Recently I was asked a qeustion that has been boggling my mind for a while now, and alas my thought processes behind answering this question is not too qualified nor too logical toward answering the question; it has been bugging me and driving me crazy, so I thought I should post it here. My knowledge of physics is quite small, but here is the question: "if a car is travelling at the speed of light, and while travelling, turns it's head lights on, what happens?"
Symmetry Canada. September 02 2009 10:18. Posts 48
I'm pretty sure light doesn't care how fast its emitter is moving, and a car can't travel at the speed of light since it's a massive object.
Anyways, I think the light appears to be moving at the speed of light from the perspective of a viewer in the car (as Micronesia said) as well as from a stationary perspective, but time is different from the perspective of the car as from the perspective of a stationary viewer. (Hence the slower aging for people going near the speed of light.)
What happens is so broad a question that you can really answer it in many ways.
1) The car remains the same at constant speed. 2) In the point of view of a bystander who could see the car moving at the speed of light would not see the light emiting from the car if standing on its side. Since the car and the light are traveling at the same speed the shining of the light would be diminished so low that you could not notice it. 3) Standing in front of the car you would see a ray of light passing you by.
etc.
Another reason the light can't project itself outside of the car is because it would mean that the light of the car is traveling faster than the car itself. Since nothing can travel faster than the speed of light. You'd probably not see light coming from the car if you were looking at it pass you by.
you -> looking at this direction car -^ lights going that way.
Last edit: 2009-09-02 10:25:48
We are going to die some day, and that makes us the lucky ones.
sigma_x Australia. September 02 2009 10:30. Posts 118
Relativity is awesome. We usually think of time and distance as constant, whereas speed is changing depending on both time and distance. In actuality, it's the other way around. Speed remains constant, and time and distance is what changes to keep it constant.
NRCC will destroy Virginia Tech... as soon as they stop dodging our exhibition challenges.
Many research papers have other ideas that weren't touched upon included in the "limitations" or "conclusions" section. The drawback being that there are a lot of terms that have complex meanings.
At least you have that quality of dwelling on something unknown to you.
That's why the car CAN'T travel at the speed of light.
From the perspective of the DRIVER, the light would zoom ahead of you at the speed of light.
From the perspective of the BYSTANDER, the light would still be moving at the speed of light, just as fast as the car is. Which is impossible. Which is why it's theoretically impossible to go the speed of light.
Now if the car was moving at ALMOST the speed of light, time would dilate for the car, making the speed of the headlight seem the same from both perspectives.
KwarK Great Britain. September 02 2009 11:01. Posts 8521
On September 02 2009 10:31 vAltyR wrote: Relativity is awesome. We usually think of time and distance as constant, whereas speed is changing depending on both time and distance. In actuality, it's the other way around. Speed remains constant, and time and distance is what changes to keep it constant.
I very much dislike this. It makes my brain hurt to think about just how far I'm moving when you take the expansion of the universe and the whirling of galaxies into account.
Misrah: by the way Einstein- you can't use sarcasm online." Aegraen: "Don't worry, if things don't change, and change in a respectable manner sometime soon, you will see the second American Revolution, because tyranny in any form, must be fought against."
ghostWriter United States. September 02 2009 11:20. Posts 2188
On September 02 2009 10:31 vAltyR wrote: Relativity is awesome. We usually think of time and distance as constant, whereas speed is changing depending on both time and distance. In actuality, it's the other way around. Speed remains constant, and time and distance is what changes to keep it constant.
I very much dislike this. It makes my brain hurt to think about just how far I'm moving when you take the expansion of the universe and the whirling of galaxies into account.
Have you ever seen the pictures where they compare the sizes of the earth to jupiter/the sun then the solar system to the largest stars ever discovered?
This is seriously mindblowing.
Today I found out her real name. No, I didn't ask her myself; when the class was doing a group assignment I walked to her desk and found her last name on a paper.
First of all that's no surprise since a massive object can't travel at the speed of light anyway (hence my claim that we should assume the car is moving very close to the speed of light). Second of all I don't believe you can use that formula for photons.
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CharlieMurphy United States. September 02 2009 14:40. Posts 17055
the most basic answer would be the lights go on but don't seem to shine anywhere.
A better way to think of it is if you take a ray of light and assume that it can shoot off another ray of light. But since they both move the same speed it would just be a brighter ray, not a longer ray.
Last edit: 2009-09-02 14:41:25
So I had ta, ya know, check 'em. (Aka SpoR)
micronesia United States. September 02 2009 14:57. Posts 9999
On September 02 2009 14:40 CharlieMurphy wrote: the most basic answer would be the lights go on but don't seem to shine anywhere.
A better way to think of it is if you take a ray of light and assume that it can shoot off another ray of light. But since they both move the same speed it would just be a brighter ray, not a longer ray.
This is the second time tonight I am speechless.
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Nitrogen United States. September 02 2009 15:01. Posts 3802
On September 02 2009 14:40 CharlieMurphy wrote: the most basic answer would be the lights go on but don't seem to shine anywhere.
A better way to think of it is if you take a ray of light and assume that it can shoot off another ray of light. But since they both move the same speed it would just be a brighter ray, not a longer ray.
This is the second time tonight I am speechless.
LOL.
"I'M FUCKING SICK OF PLAYING WITH THESE LOW SKILL RETARDS" - Testie
nimysa United States. September 02 2009 10:12. Posts 346
Symmetry Canada. September 02 2009 10:18. Posts 48
micronesia United States. September 02 2009 10:19. Posts 9999
Murlox France. September 02 2009 10:20. Posts 638
Rev0lution Albania. September 02 2009 10:21. Posts 1413
vAltyR United States. September 02 2009 10:31. Posts 524
Sky Jordan. September 02 2009 10:56. Posts 634
theonemephisto United States. September 02 2009 11:01. Posts 207
ghostWriter United States. September 02 2009 11:20. Posts 2188
citi.zen September 02 2009 12:14. Posts 456
CharlieMurphy United States. September 02 2009 14:40. Posts 17055
Nitrogen United States. September 02 2009 15:01. Posts 3802
