some scientists say a supernova can explode and send matter hurtling into space at 90% the speed of light. here's a question as a scenario...just hypothetical. if carl sagan was sitting on one side of a star before it goes supernova and stephen hawkings was sitting on the opposing side, the star explodes,.....how fast apart from each other are the two scientists traveling away from one another as the star explodes?........this question suggests that light can travel at the percieved speed we think about plus 80% or that light can only travel at 50% of what we percieve it to be.........answer the $64,000.00 question, but re-read the question word for word first,...hypothertically speaking of course.
135212
I came across the Heisenberg Principle when doing some light reading ("A Brief History of Time" - SH)and thought that it would be a great joke, if I should ever need a defense of a speeding ticket.\nBut I'll simply use it here, instead, as I'm sick of waiting for that opportunity to arise ;)\n"In another uncertainty principle joke, a quantum physicist is stopped on the highway by a police officer who asks "Do you know how fast you were going, sir?", to which the physicist responds, "No, but I know exactly where I am!"."
25100
to answer your question it is possible to go faster the the speed of light. The speed of light is 186,000 miles per second.\n\nIf zooming beyond the local speed limit is punishable by law, then some scientists may have a gargantuan speeding ticket to pay. \n\nIn a controversial experiment reported in this weeks journal Nature, scientists at the NEC Research Institute in Princeton, New Jersey claim to have broken the ultimate speed limit -- the speed of light. Though hotly contested, some say this achievement could dramatically increase the speeds at which we can send and receive information. \n\nTaught in physics classes the world over, Albert Einsteins theory of special relativity holds that no object or information can move faster than the speed of light in a vacuum, or 186,000 miles (300,000 kilometers) per second. But NECs Lijun Wang says he created an experiment in which a light beam raced through a gas-filled chamber so quickly, it exceeded the speed of light by a factor of 300. Whats more, the light pulse appears to have left the confines of the chamber before it even entered a seemingly impossible occurrence according to theories of causality, which predict that causes must always precede their effects. \n\n"It sounds crazy, but this can actually occur," said Raymond Chiao, a physicist at the University of California at Berkeley. Chiao, one of a group of researchers who have been working to break the speed-of-light limit, explained that although a common object such as a baseball could never be flung faster than the speed of light, pulses of energy with certain complex properties have been known to bend the rules. \n\n\n\n"It sounds crazy, but it actually can occur." \n\n\n\n\nIn fact, several recent experiments, including one done by Chiao earlier this year, have pointed to energy pulses zooming faster than light speed. Yet each of these experiments has been encumbered by severe limitations on measurement or observation of the energy pulses. In contrast, this latest experiment is being touted by some as the most dramatic example yet of light breaking its own speed barrier. \n\n"The effects are much larger and more spectacular" than previous observations, said Chiao. \n\nIn Wangs experiment, a pulse of light passed through a small chamber filled with atoms of elemental cesium. A light beam traveling through such a medium has two different velocities a velocity for the individual light waves in the beam and a group velocity for the entire beam. Oddly, some light waves in the beam can actually travel backward for miniscule amounts of time, creating a sort of "tail" behind forward-moving waves. As such, a light wave and its tail can leave the gas cavity at different times, creating the effect that the light beam has left the cavity before its even entered. \n\nConfused? Youre not alone. In fact, even scientists who are familiar with this area of study are unsure about the details of Wangs experiment. And many scientists said the experiments results are still open to interpretation. \n\nWilliam Happer, a physicist at Princeton University argued that several specific problems exist with the experiment, including the fact that pulses get distorted when passed through any media other than a vacuum, or empty space. In addition, he said Wang and his colleagues performed the experiment in a way that doesnt tell the whole story, and that it can be interpreted incorrectly. "This is anything but dramatic," said Happer. "If you look at the data, theres essentially no evidence that [the beam] is going faster than the speed of light." \n\nWhats more, most scientists agree that even if such a beam can be proved speedier than light, it would probably not be able to carry any information. Such a feat could conceivably allow data to be sent back in time, thus violating laws of causality and sending quantum physics into disrepair. \n\nOthers are more optimistic as to the possible
16024
It is definitely possible. However, we do not have the technology needed to reach the kind of speeds necessary to allow for travel to other solar systems, stars, etc. Here's something to consider, though. Einsteins Laws of Relativity, while not allowing travel at full light speed, do allow travel almost up to (and just short of) light speed. As you go closer to light speed, the traveler's clock would "slow down" as compared to an observer's clock on a "stationary" object. If you got close enough to light speed, you could travel across the galaxy (100,000 light years wide) in what might seem minutes or hours to you, and about 100,000 years to me. Great, great stuff. To learn more about this concept, google "twins paradox". Or go to http://media.nasaexplores.com/lessons/02-060/9-12_2.pdf and scroll down to page three. This will explain it more fully to you.
214704
This is a very intriguing question which I plan on researching. I have a conception of light and its physical properties and also the tremendous mysteries of a 'Black Hole'Where current day Physics is just beginning to grasp.NOTHING escapes the gravity of a 'Black Hole',not even light!Through the efforts  of dilligent astronomers, one was actually 'seen' and filmed as it passed in front of a known group of stars...outlining the very hole itself.(like passing an object in front of a bright light source and observing the outline of the object...i.e. Solar eclipse...,) knowing of there existence and how to track them now ,has given a whole new meaning to the destructive forces of a 'Black Hole' as it swallows up Stars, that Dwarf our Sun in comparrison,and the Solar System it may support.This is Truly Dark Matter on the 'Anti' side...Anti-matter...a Black Hole is given birth by a Star,such as our Sun, that is dying.As this Star,once a source of Light that supported a probable solar system, goes through its Final death throws it eventually explodes, but it just doesnt explode! as its  surface layers are  blasted outwards, its  core is smashed inwards. The center of the star  collapses in on itself. Billions upon Billions of tons of Star stuff crushed smaller and smaller until the whole Star is squeezed to a microscopic point,and from the remains of the dying Star, ....a BLACK HOLE is born....in our Galaxy,the Milky Way, a Massive Star explodes and creates another black hole every 1000 years. There is a estimated 10 Million Black Holes roaming our Glaxy today, creating Havoc sucking matter in around them... NOTHING escapes! As we know, anything of SUBSTANCE has mass, microscopic as well as Galatic.Once realized that the incredible forces hatched by a black hole having the ability to bend light and distort the Space/Time continuum which in itself is invisible to the eye, is it a possibility that this very same process is taking place at a molecular level? If manipulated correctly, is 'Cloaking' a possibility? your Question is very intriguing indeed!
217460
Looks like a controversy here....but no, gravity does not travel faster than light, it would take eight minutes before the earth's orbit changed.\n\n(If gravity was instantaneous, then it would be possible to use that to send messages faster than light!)
252553
Only massless particles can travel at the speed of light. Photons obviously can, since they constitute light. They can't collide, they simply pass each other. Look into a mirror...what happens? Nothing. Light goes towards the mirror, is reflected, hits the light coming towards the mirror but doesn't interact with it.\n\nVelocities don't add together in the normal sense (V = v + u) but instead they obey the relativistic formula at high velocities:\nV = (v+u) / (1+uv/c²)\nThis formula also works for lower velocities (like cars colliding) but try putting in the numbers...you'll realize it approximates extremely accurately to V = v + u
328776
The speed of light is the upper limit of speed in our space-time universe. Nothing here can be faster. And no car or any other macroscopic object can be equal to the speed of light. But the question is a thought experiment, hence, a good one indeed. Questions like this were raised by Einstein and Relativity became part of modern physical theory.\n\nSince the speed of light is an upper limit, the light from the headlamp of the relativistic car cannot be faster than the car. You won't see them in front.
323789
No, at the speed of light, the space the arrow would occupy is everything, therefore I'd only be hit by an infinite fraction of the arrow, ergo nothing would be felt, noticed nor seen. Furthermore, the arrow would take an infinite amount of time to get anywhere, although it would, from the arrows point of view, still move at the speed of light.\n\n[edit]: After having read all the other posts, I realize that I need to bring some proof of my statement since everyone are making a clueless guess. Thusly, I present to you a link to wikipedia, which fortunately validates my school/university teachings. If you search for the Lorentz Transformation (the factor of which an object stretches in relation to its velocity), you will find that at low speed this factor is very close to 1 (meaning no noticable change in stretch). Though, at a speed infinitely close to the speed of light, the factor also reaches infinity, meaning the object will have an infinite size (but not infinite mass), which means that the atoms of the arrow will hit everything at once, causing its finite momentum (movement energy) to be exerted upon every single atom in the entire universe. Not only does this mean that an arrow with the velocity of light cannot hit a single target, but it also means that nothing will notice anything other than the arrow suddenly disappearing. Furthermore, special relativity states that nothing can achieve the speed of light within a finite time-frame, making you question very theorical.\n\nI would also like to point out the sheer lunacy of the average 'answerer' here on Answers. If you take my answer as being truthful, which you should given the high support within modern physics (which I am also a student of), you would notice that only a small fraction of the members of Answers aren't guessing cluelessly. This is quite sad, and I advice you to regard every answer with suspicion, and use google/wikipedia for valification.
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.
14428
this is somewhat similar to a question I answered realative to time travel. The short answer is no, there was never a time, nor will there ever be a time when matter (massive fermions) travel faster than light (massless bosons). This is because massive objects need energy to accelerate and regaurdless of how much energy was released in the big bang, it could not have been infinite, and that is what is required to move a massive particle faster than light. Light speed is not a derived measurement, it is a fundemental constant that is the same in all reference frames. Here's the cool exception though.....and this is how a theoretical warp drive would work..... the actual expansion of space itself might have been faster than light. There has never been a limit imposed on the speed at which space expands although because gravity is a result of the deformation of space and gravitons are the theoretical force carrier, it has been assumed that the expansion of space would occur only as fast as gravitons can travel....which is most likely light speed. One of the many postulates asserted by string theory is that gravitons may not be bound to our spatial demensions, that they might radiate through extra demensions (which would account for gravity's lack of strenght compared to the other forces). If this is the case that the gravitons travel through other demensions it is quite possible that within a given reference time, a graviton could pop into a superior demension and back into our at some other point and essentially beat light to some defined location.\n\nI know thats a little confusing.....but its fun to think about.
507209
From the website taken among the other answers, I took this quasar with its 4 to 5 million - billions times brighter than the sun. If this light is the same as here around the sun, I consider that the total energy on a given sphere is a constant. But the energy density is directly related to the surface of the corresponding sphere. It growth to the second power of its radius. In other words, when the energy is 4 times the one of the sune, the earth has to be at 2 AU (300 000 000 km) from the sun to get the same light level. Having a 4 to 5 * 10^15 (million - billion) more light means 70 000 000 AU to get the same light level. Since 1 AU is 150 000 000 km, this means a 10^16 km away from the light source. This represents a 1000 light years of travel. The closest star, besides the sun, is a 4.5 light years.\nThat's bright !\n\nAnother source gives hypernovae as brightest. A value of 3 * 10^46 J is given as the same energy level as the universe (for two seconds). To have an analogous, it's necessary to go for the big bang theory. If we receive one joule per square meter and per day on earth from the sun, then the corresponding sphere for this flash is 5 millions light years big. That's brighter but damn short. Two seconds !\n\nI have a third candidate. It was much shorter and much brighter. The big band itself.
618604
Physics. Tasty, tasty physics.\n\nIt occours for the same reason a car rushing by you seems to change sound. To a stationary observer, the frequency (pitch) of the soundwaves made by the car as it drives away will decrease, so the pitch in your ear gets lower and lower as the car gets further and further from your location.\n\nSounds waves and light waves work much the same way - I used the car example to help with visualization. :3 It's all the Doppler Effect in action.\n\nSo, to answer your questions...\n\nIf space itself were not expanding, but galazies were moving away from each other, yes, redshift would still occour, since it's the light sources that matter, not the size of what they're contained in. If the stars are moving away, you will experience redshift looking at them.\n\nLight does indeed travel at a constant speed, but you've got the second part wrong. Yes, the energy, wavelength, and frequency changes. But all waves in a single medium (IE space) will have the same speed.\n\nTake a look at the equation v = lamba (f), which in words is velocity of the wave equals the wavelength times the frequency. If the wavelength doubles, frequency will halve, and velocity remains the same.
132035
Think of this\nwhen it comes to space the constant thing is the speed of light. Speed is the TIME it takes something to travel set distance.\nAt the moment we are moving through space. An hour ago we were a few hundred thousand miles from where we are now. If you were sitting still where we were a few hous ago, you would be slightly older than us.\nThis is because the constant thing in space is the speed of light. As we get closer to the speed of light either time gets smaller or distance gets smaller.\n\nIf this does not seem possible, just think of a unit of time as one vibration of an atom. Go faster, atoms vibrates slower, your time is therefore slower than some one who is still. (this is a metaphor people can comprehend, not quantum fact)\n\nSo question 1. Light is travelling at speed of light. Time and space do whatever they have to do to accomodate this.\n\nQ2 No, see Q1. You also would no be strong enough to throw the ball\n\nQ3. The closer one gets there first. just like anything else.\n\nQ4. What fuel? It would accelerate exponentially as the mass decreased. Top speed comes dowon to rates of accelerate, motor efficiency, drag, ect. Then as you got really fast your mass increases. Mass increases (again I'll use a compehendable metaphor and not quantum physics) because distance decreases, things are closer together, denser, heavier. Then your rate of fuel consumption would increase exponetially and your velocity would barely change. Then you'd run out of fuel
404852
Good question, shows you are thinking.\n\nPresent technology contends that only light, pure energy, can go as fast as the speed of light.\n\nTaking that theory to heart, if a space ship actually achieved the speed of light it would turn into pure energy (light) and cease to exist as a solid object. The test pilot would theoretically commit suicide in an attempt to learn if it was possible.
624272
In astrophysics last semester we did several things to prove to prove the friedmann equation (equation derived from general relativity that governs the expansion and motion inside the universe).  One of the proofs is the redshift caused by the expansion of the universe (not technically a relative motion but it doesn't really matter).  So here's the evidence.\n\na)The numbers for the redshift/megaparsec cross check perfectly with other independent proofs of the friedmann equation, like the cosmic microwave background.\n\nb)The supernovae we are observing are what's known as a "standard candle" meaning that the intensity, spectrum, and mass can all be determined very accurately by observing the change of the intensity of the radiation as a function of time.  Because of this fact we can take into account the gravitational redshifts.  The end result is that they make up fractions of a percent of the total redshift (I'd have to dig up my note to find the exact answer but it consider that the redshift of far objects is over 90% while the redshift from gravity is on the order of 10^-4% (.0001%).\n\nFinally to answer part of your question.  Light is not redshifted by massive objects on it's path because the gravitational potential is the same upon entering the objects potential well as when it exits.  Put another way it is blueshifted upon entering the objects gravitational pull and equally redshifted back to the original value upon exiting.
84084
Actually light travels at the same speed no matter how fast it's source is traveling, nor which direction, as long there does not exist a certain level of gravity. Brightness of light however may be relative, except that you will have a definitive amount of photons in a given space...but we have no way of measuring that. The problem with the speed of light, however, is that gravity has an effect on it. Supreme amounts of gravity can actually attract photons and slow them down, or curve their direction towards the object. we do not know whether light actually orbits black holes because it's  constant inertia gives it enough centrifugal force, or if the light is actually sucked right into the object.\n\nYes everything is relative to something else. Your name spelled in English letters is even relative to other spellings of your name. Emotions are relative, hieght is relative, color is relative, even time is relative.\n\nThis is only true if you agree with Einstein's theory of relativity, but you couldn't say you didn't agree with it, because you would have to read all of it to understand. He has math that proves everything as relative, somehow.
278823
The speed of light is invariant---no matter how fast or slow its source is moving, the speed of light remains unchanged (...please don't ask 'why?' because nobody has the vaguest idea) If you're in spaceship going at 99% the speed of light and shine a light outward in any direction, that light will move away from you at the speed of light, no faster, no slower.\n\nWith regards to the answer given that mentions the Doppler effect. The FREQUENCY (wavelength) of light is affected by the speed of the light source (Doppler effect), but frequency has nothing to do with the actual velocity of the light itself.