This is hard to ask.  If you lined up a bunch of mirrors on Mars and Earth, and had them reflecting off eachother, like mirror A on Mars points to Mirror A on Earch, then Mirror A on Earth points to Mirror B on Mars, and so on.  If you looked at a mirror on Mars with the Hubble telescope what would you see in the mirror?  Earth's past?  As the images would only reflect at the speed of light, then the time would be squared after each reflection.  So I think if you look into the mirror you might see dinosaurs.  Yes, it might sound crazy, but someone prove me wrong.  If I'm wrong, then there is no such thing as the speed of light.
215956
A number of problems.\nMars and Earth rotate.. You couldn't line them up. However, as this is a theoretical question...\nSay it took two minutes for the light to travel from Earth to mars... \nTherefore if you had 20 mirrors you'd be looking at a 40 minute lag in what you see.\nTheoretically you'd be able to see a clock reflected so many times that it would be 40 minutes slower than it actually was but you'd need some damn good mirrors and damn good optical devices.\nHowever you could only see the light you trapped.. The light from the dinasaurs went away a long time ago.\nIn order to see that you'd have to get near to the edge of our known universe in an instant.. Not so easy.\nBy trying the experiment with the mirrors you'd be able actually to prove the speed of light.\nIt would be a pretty buzzy experiment to do though...
92939
Some people would argue the logic of a space craft having headlights at all, others might find fault in the fact that, physically, nothing with mass can ever travel at the speed of light.  But lets put that aside.\n\nThe speed of light is constant in any frame of reference, no matter who is "watching" it, it always travels with respect to them at the speed of light (c).\n\nIf you are in a space ship already traveling at the speed of light [with respect to some outside observer], when you turn on the headlights, the light will move away from you at the speed of light.\nIf some outside observer (who you are flying past at the speed of light) watches all this, they would, too, see the light travel at c with respect to them.  But since you and the light are traveling both at the speed of light with respect to the observer, you and the light would be keeping up with eachother.
55033
I went and did some investigation. It definitely looks to me like the Cydonia "pyramids" are real features on the surface of Mars. However, the question is, are these natural features, or are they artificial? \n\nOf course they might be artificial, and we won't know until we get more data. However, using Occam's Razor (i.e.,the simplest answer is the best) and erring on the side of caution, I would say that the evidence is that these are just natural formations (including the "face"; see reference). \n\nHuman beings are clearly wired for apophenia (also known as the clustering illusion; seeing patterns that are not really there), and in particular, for pareidolia (experiencing optical illusions). Humans are hired-wired to see patterns, and especially faces. On closer examination, and from different angles, a lot of the resemblance of the features on Mars to regular pyramids, or of the "face" to a human face or a lion's face, just disappear. Some of the features of the face were actually due to artefacts in the imaging system!\n\nHere are some other famous examples of pareidolia:\n\nman in the moon\nold man of the mountain NH (collapsed 2003)\nnapoleon's nose rock formation (north of belfast)\n\nThis phenomenon is the basis of  Rorschach inkblot test, even. \n\nIt is hard to imagine that if there had been life on Mars, that they would have left more evidence than that. Also, surely our tests for life on the surface would have produced better evidence.\n\nThis does not mean that it is absolutely impossible that these features are artificial. However, especially given Hoagland's checkered history (see reference), and the lack of evidence, I would say that it is a low probability event. The threshold for belief that these features are artificial is understandably quite high. For outrageous claims, one needs outrageous proof.
663703
If you are traveling at light speed (which of course you cannot do) then time stops completely. Thus you cannot see anything at all in the mirror.
325663
Is this a trick question involving looking at the stars? The stars being millions of light years away it takes millions of years for the light from the stars to reach the earth, Therefore what we are seeing are the stars in the past, or something like that.
110324
Yes, time is a relative and would be preceived differently if it could be perceived from all the various perspectives.  Time and space fold in upon each other and we see a result but not the only result.
407043
Yes, we're seeing what happened to/on that planet 50,000 years ago. Light years are a measure of distance, not time; one light year is the distance that light travels in one year. Therefore, the light we're seeing from that certain planet left that planet 50,000 years ago. It's like looking back in time.
592613
There may be objects (tachyons) that move faster than light, up to perhaps infinite speeds.\nHowever, nothing already slower than light can accelerate to or beyond the speed of light.
350228
At a speed of 0.95C, twin A's clock is:\nt1=1/sqrt(1-V^2/C^2) \n\nT=1/sqrt176,700,000^2/186,000,000^2)\nor a ratio of 3.2:1 time dilation.\n\nTotal trip time: \n2*(37,000,000+{2*37,000,000*0.95})\n\nTwin B, (although long dead) will be 77,700,020 years old. Twin A, (also long dead) will ONLY be 24,281,256 years old (earth time)\n\nThis does not take into account the acceleration factor on the time dilation effects - which, obviously, are moot in this example.\n\nBottom line - to travel to a planet that is 37,000,000 light years away, you'd better go a hell of a lot faster or find a short cut.\n\nAdded: OK, let's look at 37 light years.\nTotal travel time = 77.7 years\nThe ratio is the same  3.2:1 time dilation\nThe earth twin will be 97.7 years old.\nThe traveler twin will be 44.3 years old
136074
OK, to answer this question, we first have to make a few important assumptions, otherwise the question is meaningless.\nFirst, we have to assume that you can accelerate your car to the speed of light....this is not actually possible since it would have an infinfity mass and thius take an infinite amount of energy to achiece.  Secondly, wehave to assume that at the speed of light, your head lights will opperate noramlly (i.e. you turn them on and light shines out) due to [for reasons beyond the scope of this answer] the way head lights actually work.\n\nI would also like to preface my answer with say that traveling AT the speed of light is much different than traveling just UNDER the speed of light.\n\nOne VERY important thing to remember is that in ALL frames of reference, the speed of light is constant.\nNo matter who is watching the light travel and measuring its speed, it will always come out to be the exact some value, 299,792,458 m/s exactly.\n\nWhen you, inside your car traveling at the speed of light (with respect to some "stationary" observer), swtich on your head lights and look out the wind shield, you WILL see light traveling away from you at the speed of light.\n\nIf this "stationary" observer (by which I mean a someone who you are traveling past at the speed of light) watches all this happen, both you and the light are still traveling at the same speed in his reference frame....the speed of light.\n\nSo the answer depends on who's frame of reference your talking about.  From your point of view, yes, you would see the light traveling away from you at the speed of light as if nothing was out of the ordinary.\nFrom the "Stationary" person's reference frame, you and the light would be keeping up with eachother, neither moving infront or falling behind the other one...tied.
166208
Ah a question right up my alley...Moon - no you cant see the mirror, it would take 6 seconds for a light beam to get from here to there and back. Look for the crater Tycho (most notible because of the "ray" pattern) it is in the NE corner of the moon (you will see it in the SW corner because telescopes invert the image. Several other craters and mountains, make note of shadow positions. Using a lunar chart, find the Sea of Tranquility (Mare Tranquillium) where we first set down in 1969.\n\nSun - Using a white card held up to the eyepiece (some scopes have a bracket that can do this) Line the scope up so that it points to the sun DO NOT LOOK THRU THE SCOPE USE THE SHADOW ON THE GROUND. Focus the suns image on the white card and follow sunspots.\n\nOther planets Mars - track mars throughout the year and note the stars behind it.  As you see in just a few months mars will appear to go backwards in the sky then go forward again,  This is called retrograde.\n\nYou know of jupiter and saturn ring tilt, great spot moons etc.\n\nStar clouds and star clusters - you will need a star chart and not all are visable at the same time - M42 Orion Nebulae in his belt, M31 Andromada galaxy, the only object outside our galaxy visable to the naked eye located just above the second of third pair of stars coming off the great square pegasus - in the big dipper, second star in the handle should see a double star, this was used to test ship navigators in olden times, they had to be able to see the two stars with the naked eye.\n\nThat should keep you busy for one night LOL just kidding...email me anytime you need help
40823
First of all, travelling at the speed of light is not possible, so don't even dream about travelling faster than it.\n\nBut, if it were theoretically possible, then no, you wouldn't be able to see the star reappear again. This is because light travels at the speed of light relative to everything. So when you're travelling billions of times faster than the speed of light, the light from the star will still be travelling away from you at the speed of light, so you can never catch up to it.
229022
There are numerous problems with your assertion: you measure the universe's size using the farthest object viewed from earth (13.7 billion ly).  Then you assume (from your equations) that earth is at the center of the universe (a somewhat egotistical idea), also, you forget to measure in the opposite direction (galaxies are visible at 180 degrees of the one observed to be 13.7 billion ly from here). Add to all these your interesting equivalent of the speed of light...apparently you believe the speed of light to be somewhere around 34.2 meters per second (a mere 226.4 times slower than the space shuttle).  If you are going to try to figure out the size of the universe, do a little more research and brush up on your math...for example: \n\n"From new data collected from a space probe examining the Cosmic Background Radiation, astronomers estimate the universe is at least 156 billion light-years wide. Actually, it’s long been known that the universe was a lot wider than 27.4 billion light-years; this latest research tells us how much wider.\n\nAccording to researchers writing in the journal Physics Review Letters, the universe must have expanded much faster than light in its early stage." *\n\nSo take into account that one light year is 9,467,280,000,000 km ** and you get...\n\n1.476895680 x 10^24 km\n\nthat's 1 octillion, 476 septillion, 895 sextillion, 680 quintillion kilometers wide (or 1 quadrilliard, 476 quadrillion, 895 trilliard, 680 trillion kilometers wide for those following the European system of counting)...and that disregards the continued expansion since the observations.\n\nOf course there are also quite a few scientists who affirm that the universe is infinite, so, in the end, nobody really knows.
605053
That's a good question.  If everything started from a singularity and we can see some objects from early in the universe, you'd think they'd all be in one area in space.  \n\nBut you've got to remember, where we are now was also in that same area near the original singularity.  Although our sun, or our galaxy, did not exist 13 billion years ago, this point in space did.  This point in space was surrounded by the early galaxies and quasars of the early universe and they were close to us - a lot closer than 13 billion light years.  The light of many of those early galaxies washed over this point in space long ago.  \n\nBut this point in space has been moving away from all the other points in space at a rapid rate.  We've been moving away from the surrounding points in space and the light from those points has to chase us down.  So if we've been moving away from some point in space that once contained a quasar at 9/10ths the speed of light, that light would take 10 times longer to reach us than if we were standing still.  So if that point was really 1.3 billion light years away from us 13 billion years ago, its light would just catch up with us.\n\nYou got to think 4 dimensional now... we've been moving away from points on all sides of us, thus light needs to chase us down from every direction.  So were surrounded by these ancient quasars.\n\nWell, at least the astrophysicists seem to make the math work...
494846
Mirrors reflect light, not vision, and the movement of light is independent of human involvement.\n\nA test would be to use a mirror to reflect daylight or artificial light from one room into another, darkened room. The light would make objects in the second room visible, without the mirror being observed, and the reflective path could be defined and verified.\n\nThis would not solve the problem of whether any object (including a reflection or a beam of light) exists when it is not seen (a seen photograph of unseen objects only confirms that the illusion of objects can be preserved and shared, as when you leave a room and come back again with a companion).\n\nThis is a philosophical question, rather than a physical one, since all events observed in life are subject to observation by the living observer.
25124
Well, if you're traveling faster than light, then the light can never be in front of you.  There would be just a big nothing, probably drive you crazy if you looked at it.  I know, I come from andromeda.  We travel through space backwards so we can see where we're going.
367600
Theoretically, time travel is possible. But current technology does not permit it. An interesting article appeared in Popular Science a while ago on time travel physics (see link). You're right about the stars - in that we're not looking at them in real time. In a similar vein, light from the earth reaches outward into space. An alien civilisation looking at us from far away through a telescope could theoretically view our past history. But light also weakens the further it gets away from its source, so to really look way back into our past, we'd need a really powerful instrument to detect such light patterns.