If you're in a spaceship going at the speed of light and you turn the headlights on, do they do anything?
916821
Yes the headlights will work!!  Einstein's theory of special relativity explains that space and time "dilate" as the observer approaches the speed of light so that the observer will ALWAYS be able to "measure" the speed of light to be 300 million meters per second no matter how fast he is traveling.
70554
First of your car can't go faster than the speed of light.  If your car were going faster than the speed of light, the laws of physics would not apply (since the car is breaking them), so there is no way to accurately predict what would happen.\n\nThat said, if you were going really close to the speed of light relative to some observer (keep in mind that velocity is relative, so it could just as easily be you standing still and the observer moving at near the speed of light), you would see the headlights behave perfectly normally, but he would see you almost catching up to them.  So if we imagine that you could go faster than the speed of light it would follow that everything would seem normal to you, but the observer would see you pass the front of the beam of light emitted by the headlights (actually he would see you in front of the light because he can only see the light when it reaches his eyes, and basically you would get there first, but it's the same idea).\n\n***Response to Cecil***\nAnyone with the audacity to assert that they *know* what would happen based on the laws of physics is mistaken.  Because the car CANNOT travel faster than the speed of light, and therefore the laws of physics DO NOT APPLY!  Any attempts to address this question are purely speculative, and an explaination based on science is no more likely to be correct than one based on Gene Roddenberry's imagination.  Anyone who attempts to apply Einstein's theory of relatively or any other scientific law or theory to this senario and present it as the absolute truth clearly has no understanding of the theories they are attempting to apply, and is, so to speak, the one "without a clue."\n\n***Response to Boomer***\nApparently I need to defend my answers yet again.  Nothing can travel faster than the speed of light.  There are no exceptions, and that's not a "belief," it's a fact.  Thus the car defies the laws of physics, and consequently its interactions with the physical world are unpredictable.  Meaning we cannot predict them, and thus cannot know what would happen.  And anyone who thinks that light and urine behave in the same manner is in no position to be calling others "ignorant morons."\n\n***Response to Cecil's Response***\nFirstly, if you're going to assert that your answer is correct based on the extend of your education, I strongly recommend the use of proper grammar.  As for the car and the light, if you had actually read my answer you may have noticed it is based on the assumption that the speed of light is constant.  For the person in the car, everything is perfectly normal.  He would see the light moving in front of him at 3 x 10^8 m/s and the observer (relative to whom we are measuring the speed of the car) would appear to be moving away from him faster than 3 x 10^8 m/s second, lets say 4 x 10^8 m/s.  The observer would also see the light moving 3 x 10^8 m/s, but he would see the car moving in the same direction at 4 x 10^8 m/s, so to the observer it would appear that the car reaches any given point before any of the light it had previously emmitted.  Also, I'm not sure what the doppler effect has to do with any of this, but it occurs because the wavelength of the sound waves decreases because the object creating the wave moves either closer to or farther away from the previous peak before creating the next one, not because the speed of the sound waves change.  This occurs with light as well, and can been observed as red shift and blue shift.  When this occurs, the speed of the light does not change but the wavelenght of the light is altered by the motion of its source.\n\n***Comment on Tjtindal's Response to Cecil***\nStar Trek is science fiction, but the entire concept of faster-than-light travel is pure fiction.  Nothing can move faster than the speed of light because mass increases with velocity and becomes infinite at 3 x 10^8 m/s.  Because F=ma the force need to i
75582
Tehnically, yes. Scientists succeeded in sending light through a light accelerator. Light beams are already going the speed of light so any acceleration would cause them to jump past the speed of light. The resuly was that the light actually came out the other end before it went in. This was actually measured. I heard this on NPR radio a couple of years ago.
688056
This question comes up very regularly. If you do a search you will find it has been answered dozens of times in the past few months.\n\nThe speed of light is an absolute constant. It doesn't matter what speed you are travelling at the light will always be travelling away from you at the same speed: the speed of light.\n\nThe freaky part is that the light from your headlights would seem to be travelling away form you at the speed of light (C), but to an observer who was sitting still the light would also appears to be travelling away from them at the speed of light. How can that happen? Well it's one of the tricky bits of relativity, but part of the solution lies in understanding that although light never slows down or speeds up relative to any observer it does change frequency.\n\nSo to you the light from your headlights will look quite normal, but to someone sitting still your headlights will appear to be emitting x-rays. The light would be invisible to them.\n\nThe corrolary of that is that any light approaching your windshield will be equally shifted into the x-ray part of the spectrum. Although the headlights will be emitting visible light, any time they strike an object and reflect back they will reflect back extremely low frequency light that is invisible to the human eye.\n\n\nSo no, it won't do a damn bit o good to turn on your headlights. That's not because the light won't travel, it will travel just fine. The problem will be that any light that reflects back off the road will be invisible to the human eye.
113625
The car, you, and the headlights would no longer exist.  Light would continue at its usual speed.
506771
Actually by what Einstein explained, da light will still be in  front of da car, it won't go behind u no matter how fast u r going even if u r faster dan da speed of light. Weird? rit. I too thought so, It was explained in discovery channel. Well I'll try 2 explain it 2 u, But it wud hav been easier if I cud actually show it by som animations. When u r travellin at da speed of light, time stops. Ya it does. Time is somthin like per user setting, it is unique for u & each & every one. Think dat ur carrying an Einstein's clock, which is a simple devise with 2 mirrors facing each other with a photon bouncin of the mirror. Each time it bounces from a mirror u'll hear a tic sound, that will b 1 second for u. Say u travel at a speed little less dan light u r movin forward but da photon has 2 move a lot more distance than it initially had been, which was in a straight line, but now it's motion will b som what like a hypotenuse, so it has 2 travell more distance dependin on ur speed. So ur 1 sec will not be da same as 1 sec is for som 1 on earth. So actually ur headlight will be actually movin faster dan u no matter what
211837
This is where the general theory of reletivity comes in.  if your car is moving at light speed. it needs a refrence point. Its moving light speed from one point to another point. Say point   A    is the point where you are starting, and point   B  is the point you are going to.  Since YOU are in the car moving at exactly the same speed as the car its general speed is Zero. so the lights would turn on as normal. from a third persons point... say a person on the side of the road point    C    his movement would be ZERO, and YOUR speed would be light speed, as you turn on your headlights they WOULD come on, because once again light speed is general.  Time is general, and space is general.
163148
Nothing happens, the car lights will travel at the speed of light in comparasion to the car. This doesn`t mean that the lights will travel twice as fast, you cannot add this velocities without taking into account Lorentz equations.\n\nIs it deja-vou or is it the third time this question has been asked?
1005590
hi buddy!\nscience has not developed so much that planes could fly at a speed equal to light!!!!\nhowever, if a plane is so developed, you will be able to see the light if you switch it on inside the aircraft, the same theory is applied for super sonic aircrafts. if there are two pilots inside the aircraft, they can hear their talk as both are flying at the speed greater than sound. here, relative speed comes into play. airsraft and both pilots acts as a single body. so, relatively, they are all still to each other. so, they can easily talk to eachother.\n\nif you turn on the switsh which would light a bulb outside the aircraft, then you will not be able to see it. same happens in super sonic planes. if a sound is made outside the aircraft, the pilots will never be able to hear it.!!!\n\nhope that i have answered ur querry!\nif further clarification is needed, u can mail me at mangeshome1982@yahoo.co.in
1002480
It doesn't matter if the person inside the ship isn't aware of his speed, he cannot double his speed if he started out going 99.9 times the speed of light.  Period.\n\nSo, your question doesn't have any relevance.  \n\nAlso, it is the observer from the outside that sees the slowing of time for the people in the ship.  The people in the ship aren't aware of any slowing of time, because everything including their motion inside the ship, and brain functions slow down as well.  They have no idea that their time is slowed.\n\nBut, you are correct: neither ship can go faster than the speed of light, and each ship will not see the other ship going faster than light either.  It can't even look like something is going faster, even if its speedometer shows a speed slower than light.
1061558
Moving faster than light isn't really the real issue for space travel as traveling AT the speed of light solves all the distance problems(unless you are interested in time travel!). Of course that in itself is a big challenge. If one could demass the vehicle then surely one could achieve the speed of light!!! Afterall photons do travel at this speed.\nBut we would do very well even with speeds like .99999c because time dilation will reduce the time required drastically. Have the science, just need the technology!
555954
Updated 1997 by PEG.\nOriginal by Philip Gibbs 1997.\n\n\nI am driving my car at the speed of light and I turn on my headlights.  What do I see?\n\nSadly this question and all others about experiences at the speed of light do not have a definitive answer.  You cannot go at the speed of light so the question is hypothetical.  Hypothetical questions do not have definitive answers.  Only massless particles such as photons can go at the speed of light.  As a massive object approaches the speed of light the amount of energy needed to accelerate it further increases so that an infinite amount would be needed to reach the speed of light.\n\nSometimes people persist: What would the world look like in the reference frame of a photon?  What does a photon experience?  Does space contract to two dimensions at the speed of light?  Does time stop for a photon?. . .  It is really not possible to make sense of such questions and any attempt to do so is bound to lead to paradoxes.  There are no inertial reference frames in which the photon is at rest so it is hopeless to try to imagine what it would be like in one.  Photons do not have experiences.  There is no sense in saying that time stops when you go at the speed of light.  This is not a failing of the theory of relativity.  There are no inconsistencies revealed by these questions.  They just don't make sense.\n\nDespite these empty answers, nobody should feel too put down for asking such questions.  They are exactly the kind of question that Einstein often asked himself from the age of 16 until he discovered special relativity ten years later.  Einstein reported that in 1896 he thought,\n\n``If I pursue a beam of light with the velocity c (velocity of light in a vacuum), I should observe such a beam of light as a spatially oscillatory electromagnetic field at rest.  However, there seems to be no such thing, whether on the basis of experience or according to Maxwell's equations.  From the very beginning it appeared to me intuitively clear that, judged from the standpoint of such an observer, everything would have to happen according to the same laws as for an observer who, relative to the earth, was at rest.  For how, otherwise, should the first observer know, i.e., be able to determine, that he is in a state of fast uniform motion?  One sees that in this paradox the germ of the special relativity theory is already contained.  Today everyone knows, of course, that all attempts to clarify this paradox satisfactorily were condemned to failure as long as the axiom of the absolute character of time, viz., of a simultaneous, unrecognizedly was anchored in the unconscious.  Clearly to recognize this axiom and its arbitrary character really implies already the solution to the problem.''\n\nIn 1905 he realised how it could be that light always goes at the same speed no matter how fast you go.  Events that are simultaneous in one reference frame will happen at different times in another that has a velocity relative to the first.  Space and time cannot be taken as absolute.  On this basis Einstein constructed the theory of special relativity, which has since been well confirmed by experiment.\n\nQuestions of relative velocity in relativity can be answered using the velocity subtraction formula v = (w - u)/(1 - wu/c2) (see relativity FAQ: velocity addition).  If you are driving at a speed u relative to me and you measure the speed of light in the same direction (w = c in my frame), the formula gives v the speed of light in your reference frame as, v = (c-u)/(1 - u/c).  For any speed u less than c this gives v = c so the speed of light is the same for you.  But if u = c the formula degenerates to zero divided by zero; a meaningless answer.\n\nIf you want to know what happens when you are driving at very nearly the speed of light, an answer can be given.  Within your car you observe no unusual effects.  You can look at yourself in your mirror which is moving with the car and you will lo
158568
All these answers are wrong. Light moves from each source at a speed we'll call one. If you are traveling at the speed of light, then anything that leaves you at the speed og light will be traveling the same. Now while you will not see far with your headlights, they may well provide sufficeient view, as they are ahead, to give you sight enough to drive. But you shouldn't think about changing direction. Those sorts of speed are highly unstable and could rip your car apart
591715
No. First, matter can't get to the speed of light because it would be infinitly massive and would take an infinite amount of energy to do it so the question starts out with a bad premiss.\n\nHowever, if a plane were traveling at half the speed of light and turned on it's headlights, they would be going the speed of light to him and the speed of light for someone on the ground watching. You see the speed of light is constant for all observers in a non-Newtonian reference frame.
794003
Any speed really will do. Even on modern day jet airliners the Time Dilation effect is measurable with very precise atomic clocks. Of course, its a very small amount, and you must travel at a significant fraction of the speed of light to experience a significant difference from a human perspective (e.g. at half the speed of light, the time dilation faction is about 1.15 (so time travels about 15% faster for everyone else than for you)). Though, to you, everything will 'feel' normal, as every atom in your body is experiencing the same effect. It's kinda weird (and by weird I mean awesome), but that's how it is.\n\nJust for reference here's the equation:\nt= t0/SQRT(1-(v/c)^2)\n\nWhere,\nt = the time observed in the stationary frame (say Earth)\nt0= 'proper time' the time in the moving frame (i.e. a spaceship, etc.)\nv=velocity at which the moving frame is moving\nc = speed of light
178453
Ignore the other retards who answered this.  This is actually a very intelligent question.  If you look into Einstein's theory of special relativity, you will see that no matter how fast you go (including light speed itself) light will always appear to be traveling at the same rate to you.  That means that you would still observe your headlights the same as usual.  They would still be ahead of you.  That also means that your time is slowing down greatly.  If there were a video camera on you while you were traveling this fast and someone were watching you on a monitor from the comfort of their own home, it would appear to them that you are almost frozen in time because your time reference would be so slow.  To you, your time would seem to go by at a normal pace.
33169
IF YOU WERE GOING AT THE SPEED OF A BULLET,YOU WOULD BE RIGHT NEXT TO IT AT SPEED O. THE SAME WITH LIGHT, IF YOU WERE GOING THE SPEED OF LIGHT IN YOUR CAR (LET'S SAY )YOU WOULD SEE THE LIGHT ON,BUT TO SEE THE LIGHT OFF YOU MUST BE GOING FASTER THAN THE SPEED OF LIGHT.SO THEN YOU SEE THE LIGHT ON AT THE SAME SPEED THE CAR IS GOING.