Physics

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01-12-2002, 10:28 PM
elimc

Simple physics question?

This may be a simple problem but it has been bugging me. If you make a car that can travel at .9999999999999 the speed of light (which 1986 Ford Tauruses can do) and you turn on your headlights, will you be able to see the headlights in front of you?

If the answer is yes:
Then wouldn't this violate the Law of General Relativity?

If the answer is no:
This would mean that the speed of light is relative. In that case, how can we observe the speed of light without it breaking the Law of General Relativity since earth is moving at half a million miles per hour.

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01-12-2002, 10:40 PM
elimc

I forgot to mention that this is for a . . . computer class https://www.sharkyforums.com/images/.../2005/06/6.gif

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01-13-2002, 12:22 AM
andy3109

Well first of all if you were traveling that fast yes you would see the light in front of you. This is for the same reason that if you shot a bullet on a train moving 1000 miles per hour. The bullet would just be travling 2000 miles per hour. Another words the car is already moving at a certain rate, anything that is static or has a force behind it will remain static or move ahead of the car. (if that makes any sense to you)
-andy

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01-13-2002, 12:25 AM
andy3109

To add on that, the earth's rotation wouldn't have anything to do with this equation, it would however have an effect on the angle of the headlights that appear in front of you. If a car was traveling at a certain high speed the lights of the car would appear tilted or striated.

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01-13-2002, 09:58 AM
talldude

Quote:

Originally posted by andy3109:
To add on that, the earth's rotation wouldn't have anything to do with this equation, it would however have an effect on the angle of the headlights that appear in front of you. If a car was traveling at a certain high speed the lights of the car would appear tilted or striated.

well, that bullet thingy doesn't apply to this situation. Nothing can travel faster than the speed of light. At the speed of light the energy required to move any amount of mass becomes infinite, so nothing can go faster than the speed of light. If you are not moving at exactly the speed of light (impossible) you will see light ahead of you from the headlights, although it will be very slow.

secondly, if your hypothesis is correct, the headlights would not be tilted. The light would travel at the speed of light + the speed of the car. This would mean that the light is still moving at the same pace as if the car was in a standstill, and we all know that no matter how hard you turn, the light will not bend https://www.sharkyforums.com/images/.../2005/06/5.gif.

the light will be tilted if, and only if, light cannot go any faster than the stated speed of light.

keep on topic... https://www.sharkyforums.com/images/.../2005/06/4.gif

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[This message has been edited by talldude (edited January 13, 2002).]
01-13-2002, 10:25 AM
Sinnersis

One thing that you've all forgotten is that traveling at that speed will cause time to slow down a lot - a few seconds in the car would in fact be centurys in the outside world. As a result you would indeed see the light from the headlights since it is traveling faster than you (Not much faster) and time in the car is going so slowly.

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01-13-2002, 12:27 PM
Moridin

I’m not sure why you think you would not be able to see the headlights in front of you. The key (and bizarre) thing that happens in his situation is that RELATIVE TO YOU the light behaves exactly as it normally would.

It travels away from you at the speed of light, even though you yourself are already traveling very near the speed of light. This would seem to violate the speed of light as a fixed constant idea, but it does not and that is where things get strange. To an observer stationary (relative to you) it would look like you were traveling away from them at very near the speed of light while the light from the headlights as traveling only slightly faster. I.e. they would see the difference in speeds as .00000001 * c while you in the Taurus would see it as simply c.

Light is always a constant speed relative to any observer, even though those observers themselves may be traveling different speeds.

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01-13-2002, 01:22 PM
elimc

So to another observer it would appear that you are going faster than the speed of light? And then according to their time, you would be traveling back in time?

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*Creative Statement*
01-13-2002, 01:39 PM
Moridin

Quote:

Originally posted by elimc:
So to another observer it would appear that you are going faster than the speed of light? And then according to their time, you would be traveling back in time?

??? To the external observer nothing would or could exceed the speed for light.

What the external observer would observe is the Taurus traveling almost as fast as the light from its headlights. To an observer within the car itself the difference in speed between the car and its headlights would always be c, the speed of light.

This is where time/space distortion comes into effect. The only way to account for this perceived difference is if time passed differently for someone inside the car then for the external observer.

To put it another way after n seconds a stationary observer would see a different separation between the car and it’s headlights then an observer in the car itself. Since distance is velocity * time and both observers see the same velocity, this implies that time itself actually passes differently for the two observers. Alternatively you could say distance itself changes, and this effect has been shown to occur as well.

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01-13-2002, 02:42 PM
elimc

I see, thanks. Anything else?

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01-13-2002, 03:27 PM
Moridin

Quote:

Originally posted by elimc:
I see, thanks. Anything else?

Hmmm, how about this brainteaser.

Since nothing can exceed the speed of light is it possible to complete a 100 000 light year trip in YOUR lifetime given a sufficiently fast spacecraft? Why/Why not. https://www.sharkyforums.com/images/.../2005/08/2.gif

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01-13-2002, 03:39 PM
elimc

I would say yes because when you traveled the speed of light to a planet and came back, you would be the same age as when you left. I believe that this is known as the twins paradox.

Edit
Except when you came back everyone you knew would be dead.
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[This message has been edited by elimc (edited January 13, 2002).]
01-13-2002, 03:44 PM
Moridin

Quote:

Originally posted by elimc:
I would say yes because when you traveled the speed of light to a planet and came back, you would be the same age as when you left. I believe that this is known as the twins paradox.

Edit
Except when you came back everyone you knew would be dead.

I’ll leave this for a bit to let other people get a chance to answer https://www.sharkyforums.com/images/.../2005/08/2.gif

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01-13-2002, 06:56 PM
elias5886

I think that no matter what speed you are traveling, light always travels at 186000mp/s. So yes, you would see the light, and it would look like it normally does. And, btw, how do we know nothing can break the speed of light? I believe we can, and will someday, just not in the way conventional science would think.

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01-13-2002, 08:40 PM
mrspm2003

Ok, this is confusing me a bit http://dev.www.sharkyforums.forums.relay.cool/

Lets say yo travel to mars at the speed of light, and come back to the sun. Why would you not age? I mean, if you come back everyone else you knew would be dead, but why not you? I may seem stupid, but im quite confused http://dev.www.sharkyforums.forums.relay.cool/.
Ok, distance = time*speed
so that means to get time, you would have to divide distance by speed. SO if your traveling at the speed of light(3X10*10 cm/s, correct?) SO you go to mars and back, thats a round trip of 282 million miles from the sun. So, going at the speed of light, 186000mp/s, you would get there in aprox. 1,500 seconds, right? In that time, why would you age so much yet not show the effects? I think i just confused myself...hope I did everything right https://www.sharkyforums.com/images/.../2005/08/2.gif

Quote:

Originally posted by elimc:
I would say yes because when you traveled the speed of light to a planet and came back, you would be the same age as when you left. I believe that this is known as the twins paradox.

Edit
Except when you came back everyone you knew would be dead.

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01-13-2002, 09:00 PM
yargman

Quote:

Originally posted by elias5886:
And, btw, how do we know nothing can break the speed of light?

right now the theory is that objects gain mass the closer they get to the speed of light, i think this has been confirmed by several experiments
of course it is merely a theory, not an immutable law written in stone

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01-13-2002, 09:02 PM
yargman

Quote:

Originally posted by Moridin:
Hmmm, how about this brainteaser.

Since nothing can exceed the speed of light is it possible to complete a 100 000 light year trip in YOUR lifetime given a sufficiently fast spacecraft? Why/Why not. https://www.sharkyforums.com/images/.../2005/08/2.gif

some "creative" ways that have been thought up include suspended animation - basically "freezing" you (using subzero temps or not) so that your life basically experiences a big long pause, and you wake up after 100k years

and i think if wormholes do exist, you may be able to surpass the speed of light, not real sure

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01-13-2002, 10:51 PM
ilkpc's

present theoretical physics supports 1. substanially different particle make-up/behavior from your discussion; 2. multiverse probable existance; 3. c now recognized as having varying value under different conditions; 4. frame of reference of observer must be clearly defined

the light "beam" reference must take into account multiple simultaneous observers ... to be valid today ... cheers
01-13-2002, 10:55 PM
elimc

Quote:

Originally posted by elias5886:

I think that no matter what speed you are traveling, light always travels at 186000mp/s. So yes, you would see the light, and it would look like it normally does. And, btw, how do we know nothing can break the speed of light? I believe we can, and will someday, just not in the way conventional science would think.

During the early origins of the universe, the Laws of General Relativity did not apply. The crap that resulted from the big bang singularity accelerated faster than the speed of light until quantum mechanics had less of a play in the universe. Perhaps we will be able to create that state in a lab to send something at more than the speed of light (some say a 1986 Ford Taurus).

BTW, I like your name Elias.

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01-13-2002, 11:03 PM
elimc

Quote:

Originally posted by mrspm2003:

Ok, this is confusing me a bit
Lets say yo travel to mars at the speed of light, and come back to the sun. Why would you not age? I mean, if you come back everyone else you knew would be dead, but why not you? I may seem stupid, but im quite confused .
Ok, distance = time*speed
so that means to get time, you would have to divide distance by speed. SO if your traveling at the speed of light(3X10*10 cm/s, correct?) SO you go to mars and back, thats a round trip of 282 million miles from the sun. So, going at the speed of light, 186000mp/s, you would get there in aprox. 1,500 seconds, right? In that time, why would you age so much yet not show the effects? I think i just confused myself...hope I did everything right

See below

Quote:

Originally posted by Moridin:

To put it another way after n seconds a stationary observer would see a different separation between the car and it’s headlights then an observer in the car itself. Since distance is velocity * time and both observers see the same velocity, this implies that time itself actually passes differently for the two observers. Alternatively you could say distance itself changes, and this effect has been shown to occur as well.

Edit
Two young twins are separated at birth. One is sent the speed of light to another galaxy and back. When the twin arrives back to earth his brother has aged into an old man.

Pretty weird, but a couple of experiments have confirmed it.

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[This message has been edited by elimc (edited January 13, 2002).]
01-14-2002, 12:13 AM
dudephil

Quote:

Originally posted by elimc:
Edit
Two young twins are separated at birth. One is sent the speed of light to another galaxy and back. When the twin arrives back to earth his brother has aged into an old man.

Pretty weird, but a couple of experiments have confirmed it.

What experiments? You are getting too far away from logic and too close to scientific reasoning. There is a fine line between those. There is no way 2 people are born at the same time then find each other,lets say 50 years later,(no matter what) and are not the same age. It might be scientifically possible(in theory), but not PHYSICALLY possible. (Common sense)

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01-14-2002, 12:43 AM
macutty

Quote:

Originally posted by elimc:
This may be a simple problem but it has been bugging me. If you make a car that can travel at .9999999999999 the speed of light (which 1986 Ford Tauruses can do) and you turn on your headlights, will you be able to see the headlights in front of you?

If the answer is yes:
Then wouldn't this violate the Law of General Relativity?

If the answer is no:
This would mean that the speed of light is relative. In that case, how can we observe the speed of light without it breaking the Law of General Relativity since earth is moving at half a million miles per hour.

from hawkings "A brief history of time":

" As we have seen, Maxwells equations predicted that the speed of light should be the same whatever the speed of the source, and this has been confirmed by accurate measurements. It follows from this that if a pulse of light is emmited at a particular time at a particular point in space, then as time goes on it will spread out as a sphere of light whose size and position are independant of the speed of the source."

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01-14-2002, 12:47 AM
macutty

nm

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C900@1333 w/Alpha PAL6035----------------------C566@850
CUSL2-C------------------------------------------P2B-f
256MB Micron-------------------------------------256MB Micron
Elsa GF2MX 32MB----------------------------------Creative TNT2 Ultra
QuantumFB 20G ATA100/7200----------------------2X WD 13G ATA66
SBLIVE! Value-------------------------------------SBLIVE! Value

[This message has been edited by macutty (edited January 14, 2002).]
01-14-2002, 02:49 AM
ilkpc's

i have a deep respect for stephen hawkings, but his work is no longer entirely current ... leading edge theory has moved on ... & i'm not aware of any mass market publications ...
01-14-2002, 03:04 AM
ilkpc's

this is 1 of several resource websites:
http://www.ictp.trieste.it/ictp/prep...001LIST_1.html

pls respect author's copyrights if you quote from these papers

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