# A HARD question NONE of you will get.

ChessManCLoss
Posers and Puzzles 28 Oct '06 21:33
1. 28 Oct '06 21:33
If you are going the speed of light in a car, and you turned on your headlights, would you see them? Also another question. If you are going the speed of sound in a car and you turned on the radio, would you hear anything?
2. 28 Oct '06 22:01
Originally posted by ChessManCLoss
If you are going the speed of light in a car, and you turned on your headlights, would you see them? Also another question. If you are going the speed of sound in a car and you turned on the radio, would you hear anything?
it is physicily impossible to travle the speed of light.
3. 28 Oct '06 22:16
drumset04 is right it is impossible for an observer to travel at the epeed of light. But theoretically if you could you would see the headlights as light always appears to travel at the speed of light rellative to any observer at any vellosity (these are the basics of specsial relativity).

For the second part, yes you would hear the radio as normal as long as it was in the car. this is because the sound waves are emmited from the speakers with there normal velosity plus the vellosity of the car (the car and radio are in the same inertial frame).

Note: the sound could be slightly distorted if the car was accellerating at any speed.
4. SiteNine
Zinc Saucea
29 Oct '06 01:04
Originally posted by danandi1
drumset04 is right it is impossible for an observer to travel at the epeed of light. But theoretically if you could you would see the headlights as light always appears to travel at the speed of light rellative to any observer at any vellosity (these are the basics of specsial relativity).

For the second part, yes you would hear the radio as normal as lo ...[text shortened]... ame).

Note: the sound could be slightly distorted if the car was accellerating at any speed.
5. 29 Oct '06 01:49
Originally posted by SiteNine
A sonic boom occurs to people standing still, not the person in the vehicle. right?
6. 29 Oct '06 02:14
Originally posted by drumset04
it is physicily impossible to travle the speed of light.
its a hypothitical question. you can go the speed of light and sound but you cant do it in a car.
7. AThousandYoung
All My Soldiers...
29 Oct '06 03:47
Originally posted by ChessManCLoss
its a hypothitical question. you can go the speed of light and sound but you cant do it in a car.
No, you CANNOT go the speed of light.
8. 29 Oct '06 06:34
Originally posted by danandi1
drumset04 is right it is impossible for an observer to travel at the epeed of light. But theoretically if you could you would see the headlights as light always appears to travel at the speed of light rellative to any observer at any vellosity (these are the basics of specsial relativity).

For the second part, yes you would hear the radio as normal as lo ...[text shortened]... ame).

Note: the sound could be slightly distorted if the car was accellerating at any speed.
That's completely wrong! No you would not see headlights.

We have to assume that if you are in a car traveling the speed of light we'll need lots of empty space in front of us. Since you don't actually see light (as a driver) until it's reflected off of something in front of you. And since we know there is nothing in front of you (or you would have crashed into it) you will not see your headlights!
9. 29 Oct '06 06:49
Originally posted by SiteNine
This is completely different. Sound waves travel through air (by compressing it locally) and thus completely relative to the speed of the air it is immersed in. I.e. the air in the cab of the car is also traveling the speed of "sound" relative to an observer. However, relative to the speaker, the air is stationary therefore the sound wave travels exactly as it normally would within the confines of the cab of the car.

Light is different. Light does not travel "through" a medium, at least, none that we know of. It has different properties entirely.

Sonic Boom is entirely different phenomenon and would be external to the cab of the car. The air outside of the car is not stationary relative to the radio. I suggest you read this:

http://en.wikipedia.org/wiki/Sonic_boom
10. 29 Oct '06 11:03
Originally posted by Sickboy
That's completely wrong! No you would not see headlights.

We have to assume that if you are in a car traveling the speed of light we'll need lots of empty space in front of us. Since you don't actually see light (as a driver) until it's reflected off of something in front of you. And since we know there is nothing in front of you (or you would have crashed into it) you will not see your headlights!
That's rubbish, you could use the same argument for a car travelling at non relativistic speeds.

When you are in a normal car you see the light reflected off things on the side of the road and the road itself, this case would be no different.

NEVER SAY SOMEONE IS COMPLETELY WRONG UNLESS YOU KNOW THAT IT IS TRUE!
11. 29 Oct '06 11:35
Originally posted by danandi1
That's rubbish, you could use the same argument for a car travelling at non relativistic speeds.

When you are in a normal car you see the light reflected off things on the side of the road and the road itself, this case would be no different.

NEVER SAY SOMEONE IS COMPLETELY WRONG UNLESS YOU KNOW THAT IT IS TRUE!
This case would be different. For you to see reflected light there has to be time for the light waves to travel from the source to the object, and then from the object to your eye. If both you and the light source are moving together at the speed of light then there is not time for this to happen, you will pass objects before the light reflects off them.
12. 29 Oct '06 11:41
Originally posted by Ian68
This case would be different. For you to see reflected light there has to be time for the light waves to travel from the source to the object, and then from the object to your eye. If both you and the light source are moving together at the speed of light then there is not time for this to happen, you will pass objects before the light reflects off them.
I explained why this is not the case in my first post. Special relativity states that any observer at any velosity will see the speed of light relative to themselves as the actual speed of light.

So an stationary observer would see te car travel at the speed of light but not see the light that it is emmitting. The observer in the car would see the light travelling away from himat the speed of light
13. 29 Oct '06 11:51
Originally posted by danandi1
I explained why this is not the case in my first post. Special relativity states that any observer at any velosity will see the speed of light relative to themselves as the actual speed of light.

So an stationary observer would see te car travel at the speed of light but not see the light that it is emmitting. The observer in the car would see the light travelling away from himat the speed of light
You only see light if:

a. you have a direct line of sight to the source, which in this case you don't.

or

b. you see the light reflecting off something else, which cannot happen for the reason I gave before.
14. 29 Oct '06 12:01
Originally posted by Ian68
You only see light if:

a. you have a direct line of sight to the source, which in this case you don't.

or

b. you see the light reflecting off something else, which cannot happen for the reason I gave before.
You nare able to see the light reflected of other objects as in a normal car as explained in my last post (if you do not understand special relativity the it can be confusing)
15. 29 Oct '06 12:29
obviously there are countless obstacles to each scenario but the answer to both is yes, at some point in time.