Headlights at the speed of light.....
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Headlights at the speed of light.....
I'm not a frequent visitor to this section but somebody in Private Flying suggested I asked my question here.
To tie up an old debate I have been having with a friend can somebody give me the UNDOUBTEDLY CORRECT answer for the following?
The driver of a car travelling at night time at the speed of light turns his headlights on, do they light the way ahead of him?
To tie up an old debate I have been having with a friend can somebody give me the UNDOUBTEDLY CORRECT answer for the following?
The driver of a car travelling at night time at the speed of light turns his headlights on, do they light the way ahead of him?
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if you were sat immediately above the lights then no, you wouldnt see anything because the car arrives on the surface taht would reflect your lights immediately, but say you were 1.5m behind the lights (approx. driving position) then your brain would have 0.0000000025 seconds to interpret the signal and see the light, which i believe is a bit too quick
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the UNDOUBTEDLY CORRECT answer:
(if the current understanding of the universe is undoubtedly correct)
Yes
no matter what speed you are travelling at, the speed of light is constant relative to your motion.
ie the light still travels away from you at the speed of light, even though you are travelling at the speed of light.
... that's what relativity is all about
Hence the lights would light the way ahead of you... (from your perspective at least).
Mind you, travelling at about 670 million miles per hour but only lighting the road a few hundred metres ahead might not be much use after all...
(if the current understanding of the universe is undoubtedly correct)
Yes
no matter what speed you are travelling at, the speed of light is constant relative to your motion.
ie the light still travels away from you at the speed of light, even though you are travelling at the speed of light.
... that's what relativity is all about
Hence the lights would light the way ahead of you... (from your perspective at least).
Mind you, travelling at about 670 million miles per hour but only lighting the road a few hundred metres ahead might not be much use after all...
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As an object's speed increases, so does its mass until at the speed of light the mass is infinite. Therefore you would be unable to:
a) Lift your hand to reach the light switch;
b) Move the light switch; or
c) Open your eyelids to observe the results!
However, I do agree that the speed of light is constant, relative to the observer, irrespective of the observer's speed.
a) Lift your hand to reach the light switch;
b) Move the light switch; or
c) Open your eyelids to observe the results!
However, I do agree that the speed of light is constant, relative to the observer, irrespective of the observer's speed.
ddraig wrote:
"the UNDOUBTEDLY CORRECT answer:
(if the current understanding of the universe is undoubtedly correct)
Yes
no matter what speed you are travelling at, the speed of light is constant relative to your motion.
ie the light still travels away from you at the speed of light, even though you are travelling at the speed of light.
... that's what relativity is all about"
Thats wrong, like Einstein tells us, the speed of light is 300000 km per second.
Thatīs a fixed speed.
So if you are travelling with lightspeed, it will remain dark in front of you.
"the UNDOUBTEDLY CORRECT answer:
(if the current understanding of the universe is undoubtedly correct)
Yes
no matter what speed you are travelling at, the speed of light is constant relative to your motion.
ie the light still travels away from you at the speed of light, even though you are travelling at the speed of light.
... that's what relativity is all about"
Thats wrong, like Einstein tells us, the speed of light is 300000 km per second.
Thatīs a fixed speed.
So if you are travelling with lightspeed, it will remain dark in front of you.
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Thanks for the response although I must admit I'm still none the wiser.....
I posted this thread in Private Flying too and the response was just as mixed. Perhaps there is no definitive answer but at least it makes us wonder.
How about.....
If a marksman fell from an aircraft at the speed of a bullet from a gun and he fired his gun up at the aircraft............would it leave the barrel or would it stay in the barrel???????
I posted this thread in Private Flying too and the response was just as mixed. Perhaps there is no definitive answer but at least it makes us wonder.
How about.....
If a marksman fell from an aircraft at the speed of a bullet from a gun and he fired his gun up at the aircraft............would it leave the barrel or would it stay in the barrel???????
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yes, of course, travelling at the speed of light is not possible, but the question still has its merits. It is useful to help in the understanding of relativity.
Ignoring the (minor!) problem of it being impossible, i stand by my earlier response...
... let's say you're travelling at 0.99*c (c: the speed of light) to make it just practically impossible.
Einstein's theory tells us that the speed of light is constant relative to any inertial (that is, non-accelerating) frame of reference. It does not say that the speed of light is constant relative to just one inertial frame as suggested. That is what newton's laws were all about.
It seems that the common misconception with this type of problem is as follows:
If you are travelling at .99c, and the light is travelling away from you at speed c, then the surely the light has speed 1.99c. This is not the case.....
Relative to you the light has speed c, and relative to a stationary observer the light also has speed c, not 1.99c... Even if you could travel at 1000c, the speed of light relative to you would still be c.
So according to Einstein's theory of relativity the definitive answer to the question...
it's not possible.. but if you could get to that speed, then yes.. the road would be lit...
Ignoring the (minor!) problem of it being impossible, i stand by my earlier response...
... let's say you're travelling at 0.99*c (c: the speed of light) to make it just practically impossible.
Einstein's theory tells us that the speed of light is constant relative to any inertial (that is, non-accelerating) frame of reference. It does not say that the speed of light is constant relative to just one inertial frame as suggested. That is what newton's laws were all about.
It seems that the common misconception with this type of problem is as follows:
If you are travelling at .99c, and the light is travelling away from you at speed c, then the surely the light has speed 1.99c. This is not the case.....
Relative to you the light has speed c, and relative to a stationary observer the light also has speed c, not 1.99c... Even if you could travel at 1000c, the speed of light relative to you would still be c.
So according to Einstein's theory of relativity the definitive answer to the question...
it's not possible.. but if you could get to that speed, then yes.. the road would be lit...
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Another one, you say?
OK, this one used to keep us entertained for 15 hrs as we trundled across the North Atlantic in a C-130...we still don't have the answers....so here goes.....
A C-130 takes off with a load of Budgie birds. When loaded, it was kind of cool, so the birds were at rest and content! Therefore, when the birds were weighed on the scales, the total of their weight came to 30,000 lbs! Huge birds!!!
Now, the aircraft gets airborne and strikes off to it's destination. The birds become excited and start flying around in their huge cage....The question now becomes:
Does the aircraft still have the weight of 30,000 lbs with the birds all flying around, or do the birds still exert their weight on the aircraft?
OK, this one used to keep us entertained for 15 hrs as we trundled across the North Atlantic in a C-130...we still don't have the answers....so here goes.....
A C-130 takes off with a load of Budgie birds. When loaded, it was kind of cool, so the birds were at rest and content! Therefore, when the birds were weighed on the scales, the total of their weight came to 30,000 lbs! Huge birds!!!
Now, the aircraft gets airborne and strikes off to it's destination. The birds become excited and start flying around in their huge cage....The question now becomes:
Does the aircraft still have the weight of 30,000 lbs with the birds all flying around, or do the birds still exert their weight on the aircraft?
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first off, that is about 450,000 budgies. Cramming them into the back of a c-130, I doubt they will have the room to fly.
Assuming the a/c is sealed, then yes, they will weigh the same flying or not, due to the downdraft effect.
Assuming the a/c is sealed, then yes, they will weigh the same flying or not, due to the downdraft effect.
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another good'n
heres another great one, i know theanswer, but lets see what you lot think...
a man stood in a train facing the direction of travel fires a rifle at a target sat at the opposite end of the carriage.
another person on the train times the interval between him pressing the trigger (exactly) and the bullet hitting the target.
The train is moving at 120mph say.
Another observer, stood on the ground beside the track as the train goes past also times the interval between the chap pulling the trigger and the bullet hitting the target.
Are the times the observers record the same?
(Hint: This helps to prove that time is not after all constant!!)
a man stood in a train facing the direction of travel fires a rifle at a target sat at the opposite end of the carriage.
another person on the train times the interval between him pressing the trigger (exactly) and the bullet hitting the target.
The train is moving at 120mph say.
Another observer, stood on the ground beside the track as the train goes past also times the interval between the chap pulling the trigger and the bullet hitting the target.
Are the times the observers record the same?
(Hint: This helps to prove that time is not after all constant!!)
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To answer the original question, everything that you (the driver) could see around you (including the sides and back) would be concentrated into a infinitley compressed small bright point just in front of your eyeballs. Your headlights, the road, stop signs, frightened roos etc and your CD-player lights as well as your rear lights would all be in that bright point. So basicaly your stuffed as far as seeing anything ahead. Yep the headlights are in fact shinin on the road ahead of you, and the last thing a goanna would see before you took him out would be your headlights hittin his eyes at exactley C. Also the time taken to get wherever you were goin to at such a great rate of knots would be zero as measured by your watch. If you drove to Proxima Centauri (nearest star) youd be there in an instant but we back on Earth would measure 4.25 years in real time (as against apparant time which would be 7 years near enough).
Since C is a constant to observers, then time is the variable. The road-side garage bloke would see you wizzin past at C but hed definatley see your headlights (and your rear-plate rego too!).
Since C is a constant to observers, then time is the variable. The road-side garage bloke would see you wizzin past at C but hed definatley see your headlights (and your rear-plate rego too!).
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Oh yeah, tell it to Gene Rodenberry
Or possibly Han Solo. And what about Warp Drive?
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Well it has to be said that although your mass "increases" as you approach the speed of light "c" it's all RELATIVE. ie your eyelids will still weigh the same to you at c as they do to you at human speed. so you will be able to open them and see.......I think.
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What car does the speed of light and at night time to? Little boy racer lol. I think the correct answer is the one that it would, because it is travelling from its source at a constant speed, and if the source (light on the car) is moving foreward at the speed of light, then the light will stil travel foreward.
As for the marksman, if he is falling to the ground from FL350 at the speed of a bullet, and fires a bullet from a gun, what ever good that would do to save him, the bullet will leave the gun at the normal bullet speed so to speak.So would it not exit the rifle at the usual speed, but because the rifle is doing bullet speed, it would appear to exit at twice the speed but only be doing its normal speed, it appears as two times faster as it is going x m/s that way < and we are going this way > at bullet speed?
Just a thought, keep these coming, very interesting to ask and pass time.
As for the marksman, if he is falling to the ground from FL350 at the speed of a bullet, and fires a bullet from a gun, what ever good that would do to save him, the bullet will leave the gun at the normal bullet speed so to speak.So would it not exit the rifle at the usual speed, but because the rifle is doing bullet speed, it would appear to exit at twice the speed but only be doing its normal speed, it appears as two times faster as it is going x m/s that way < and we are going this way > at bullet speed?
Just a thought, keep these coming, very interesting to ask and pass time.
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When standing on the platform at an underground station as the train approaches there is an onrush of air ahead of it. If the train was travelling at the speed of sound would there be an onrush of air ahead of it (I know the answer!)?