A: If your car could travel at the speed of light, would your headlights work?
A: Yes, er, no, er, wait a minute! This is a trick question. I don't like trick questions. I think you must be one of them dad-burn pinko-commie-hippie-trouble makers. Get offa my lawn!
Actually, yes they would. There is no absolute velocity. There is only relative velocity. The light given off by things coming at you is blue shifted, light from things going away is red shifted. When light is blue shifted the apparent wave length goes down and the frequency goes up. Just the opposite happens when it is red shifted: the wave length gets longer and the frequency gets lower.
On earth, shoot, even in the solar system, relative velocities are too small to make a noticeable difference. But you get going really fast and it does start to become noticeable. When they talk about the red-shift of light from stars they are talking about measuring how fast the stars are going away. If they were going really fast, the light would get shifted down into the infrared or even the microwave region.
Things approaching each other will see the light of the other blue-shifted. If they were going fast enough the light would shift into the ultra-violet range, then X-rays and finally gamma rays.
So if you were driving down the road at the speed of light, everything in front of you would be being blasted by really powerful gamma rays. Any light reflected back at you would be the same. Put on your super gamma ray goggles. Any light from your taillights would be so red shifted as to be undetectable.
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Ah, but if you were going at the speed of light (relative to me) I would percieve that you had no time (sic!) to turn them on!
just turn them on before you take off and you won't be able to catch up with them(the lights)
Question: If your car could travel at the speed of sound, would your ears work?
Yes, your ears would still work, but mostly what you would hear would be sounds from inside the car. You would not hear sounds coming from things behind the car (things you had already passed). Any sounds coming from ahead of you would be squished into a shorter, higher frequency. And it would have to be pretty loud to be heard over the noise of air rushing by. And maybe not. The shockwave set up by your car hitting the air might effectively block out any sound coming from in front of you.
And if you were driving a covertible with the top down, forget about hearing anything at all.
Nearly right, Charles.
Having flown aircraft at over twice the speed of sound I can tell you that
1) You can hear anything inside the plane as its going the same speed you are.
2) You don't hear the sonic bang as the shockwave is with you, not passing you.
3) You don't hear the shockwave of your wingman either.
OK Stu, you can't just throw a comment like that out there. You have to tell us the whole story, or at least tell us where to find it, if you've already told it somewhere else.
But speaking hypothetically, I mean we are driving a supersonic convertible, suppose you passed another vehicle traveling supersonic going the other way. Would you hear the boom? Or would you and your vehicle just disintegrate?
Or how about if someone was shooting a cannon at you (but missing) would you hear the report from the cannon?
1) http://www.savory.de/blog_feb_09.htm#20090207
2) You would hear opposite traffic within the approach cone.
3) You would only hear the cannon if it was within the approach cone (e.g 180° at Mach 1, less if you are faster).
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