Yes, it's true! You can move something on the moon faster than the speed of light. It's all in the wrist.

You will need:


  1. Wait for full moon.
  2. Put batteries in laser pointer.
  3. Switch pointer ON.
  4. Point beam at moon.
  5. Flick wrist.
That's it! The area of the moon you're lighting up will move faster than the speed of light! If you don't believe me, work it out...


  1. No natural laws are broken in the course of this experiment.
  2. No information is transferred, either.
  3. It has been brought to my attention that concern by some elders has been expressed as to the physical possibility of said experiment. The diameter of the moon is approximately 3500km, and it subtends an angle of 0.5degrees. To attain light speed of 300000km/s, we would have traverse it in something above 0.01s. My wrist can do 90 degrees in well under 0.18s, which would translate to the desired speed.
  4. It has furthermore been brought to my attention that some elders have expressed their concern that "things" may not really be things. Are they ideas, persons or places?? The short answer is that it depends on what things are. For the same answer but without short non-technical words, I can do no better than refer the interested reader to genidentity. I can also recommend genidentity for readers who are interested in Philosophy rather than just in making fun of Physics; the long words are more needed for that purpose.
  5. If you really insist on doing it right even quantum mechanically, try quantum entanglement and faster than light communication!
So Einstein said that nothing can travel faster than the speed of light, and in fact getting anything going at any relativistic speed at all isn't feasible. So what? There are ways of getting around this. The real trick to moving something faster than light speed is to remember that "velocity" is just the distance traveled divided by how long it took to travel there.

  • Warping Space: As seen in Star Trek as warp drive. Ever been on a long car trip through many small towns, or roads you know are infested with highway patrolmen, and wished that the road would just get shorter since you can't go any faster? That somehow a mile would only be half as long? That's exactly what warping space does. You make the space in front of you "smaller" than it actually is (possibly using a gravity field), thus increasing how much distance you cover without actually increasing your speed. For example, if one could warp space in front of one's car by 10%, a mile would only be 4752 feet long, and a car travelling at 50 miles per hour would cover a little over 55 miles in an hour. Hence, you could travel 186,001 miles per second without pushing your speed above 169,092 miles per second.

  • Folding Space: As seen in the book A Wrinkle in Time in the form of the tesseract. Madeleine L'Engle explains folding space in the book by imagining a string stretched between your fingers. Now imagine that there's an ant at one finger who wishes to get to your other finger, so he is going to have to walk all the way across the string. It would certainly make the ant's job much simpler if you'd just bring your two fingers together, now wouldn't it? Of course, space is a bit more complicated than that, and you can't just ask someone to fold it for you. An immense gravitational force might be enough to fold space like this, though the energy requirements would be astronomical, and by some estimates, exceed the total ammount of energy knowt to exist in the universe. Travel would be instantaneous, so you could travel the entire span of the universe in no time at all, with an effectively infinite speed.

  • Tunneling Through Space: As seen in the movie Event Horizon as the thing that sent a ship full of folks to Hell somehow, in Deep Space Nine as a quick way to piss off the Cardassians, and in Contact as the thing that aided Jodie Foster's breasts to a zero-gravity perkiness. Also known as wormhole, or Einstein-Rosen Bridge travel. As Sam Neil stated in EH, the shortest distance between two points is not a straight line, but zero. He illustrated the point by drawing two points on a piece of paper, folding the paper so that the points were in the same spot, and then poking his pencil through the paper. At first glance, space tunneling looks just like space folding; however, space tunneling does not fold space. It bridges two separate points in space by poking a hole in the fabric of space itself. You go in one hole, and instantly emerge at the other one, like the playing field in "Asteroids." (actually, that's a torus, but you get the idea) Black holes are thought to create these "pokes" in space. They could be used to move something faster than the speed of light, if only they weren't unstable and didn't immediately crush you to maximum density as soon as you got past the accretion disk, not to mention the fact that we have no idea if they open up anywhere. A wormhole, more or less, would be a stable black hole that opened up somewhere else and didn't crush you. Again, travel would be as close to instantaneous as makes no difference.
  • Hyperspace: As seen in Star Wars as the hyperdrive, a rarely working feature on the Millenium Falcon. Imagine playing with toy cars on an old, warped, gritty table, where the cars are hard to slide back and forth. The cars can't really get going very fast at all. It's much faster to pick them up to move them from place to place, but to pretend like they're still cars, you hold them up just a little ways from the table, so they can still interact with whatever else you're playing with. A hyper-space is a space that is somehow above or beyond "real" space. Anyhow, the idea is that travel in a hyperspace is somehow shorter than in real space; either time goes slower, or distance is shorter, or maybe both. You go into hyperspace at one point, travel a ways, and drop out of hyperspace quite a long ways farther along in real space than you flew in hyperspace. When you picked up the toy car, you moved it through a hyperspace (the space above the table, to be specific). There was no old table to worry about, just like there would be no physical world to worry about in hyperspace. Still, you had to keep interacting with your play world, so you didn't pick the car up too far. Moving into a hyperspace would be really hard to do, and you couldn't get too far away from real space or you might not be able to find your way back; it would be like going out to sea on a foggy night without a compass. So when you hit hyperspace, you haven't really left this dimension. There's still an "echo" of you in real space, and there are "echoes" of real things in hyperspace. Speeds through hyperspace would be like speeds through warped space, with your apparent speedup being determined by how much faster hyperspace was than real space.
Right then! So now that we all know how to move something faster than the speed of light, I want to see you people devising ways of doing this by the end of the century. Bloody hell, it's almost 2002 and we have yet to send something alive to Mars. Makes me weep for the future...
All content for this node (minus the smart-ass asides about Jodie Foster) courtesy of Prof. Benjamin Blackhawk's "Let's Get Hyper(spaced)!" summer course, which I took eight years ago. I've never seen the world the same way since.

Why try to get an object to travel beyond c (the speed of light)? Another way to move faster than light is slowing down light or even stopping it.

Photons are massless, and that's why they can travel as fast as they do. So we need to weigh photons down in order to slow them down.

The technique to accomplish this requires warm rubidium vapours, a glass cell and two lasers, a "control laser" and a "signal laser". The signal laser is the one to be stopped. Using the control laser, we can cause rubidium gas in a glass cell to become "dispersive" -- in other words, the velocity of light passing through the gas depends sensitively on the colour of the light. In such a dispersive gas, atoms and photons interact strongly. Effectively dragged down by strong interactions with atoms, the photons will slow to a "crawl". An atom-photon system like this is called a "polariton".

Next we reduce the intensity of the signal laser until the polariton is 100% atomic. There will be no photons left inside the chamber. Yet the imprint of the photons will remain -- on the atoms themselves. Information describing the fading laser pulse will be stored, like a code, in the up-and-down patterns of the atoms' spin axes, from where it can be released afterwards by another laser beam directed through the chamber.

Does this sound like science fiction to you? It's only quantum physics. Scientist at Harvard University managed to slow down light by sending it through atomic vapours (extremely cold sodium gas can be used as well as warm rubidium) in 1999 and to stop it completely about two years later. So all you need to travel faster than light is a bicycle and a Harvard quantum physics lab to drive by.

The basic idea in special relativity that nothing can travel faster than the speed of light is a consequence of the Lorentz transformation equations, which if they hold exactly, it would indeed be true that getting to the speed of light would require infinite energy. There are, however, indications that Lorentz invariance indeed does only hold as an approximation. There is a growing body of evidence, both theoretical and experimental that shows that some of the predictions of Lorentz invariance do not exactly hold.

First from a philosophical standpoint. The two pillars of modern physics of the present day, quantum field theory and general relativity, both developed and use equations that describe the vacuum that look remarkably like the equations of fluid mechanics, i.e. they describe free space as though it were a material medium. In classical fluid mechanics with the linear partial differential equations that are used to approximate the behavior of the fluid, we have the result that exceeding the wave speed of the underlying medium would result in infinite pressure. Naively, we might then say that it's impossible to break the speed of sound in a medium. Of course, everyone knew that these linear equations were only approximations and more complicated nonlinear equations needed to be developed to describe the behavior of the fluid at transonic and supersonic conditions. From this point of view, we might say that the same situation might be true for these equations that are being developed at the frontiers of modern physics.

A seeming sign that Lorentz invariance does not hold exactly comes with the formulation of quantum electrodynamics, and Richard P. Feynman's infamous renormalizations. The requirement for mass and charge renormalizations in QED is a signal that Lorentz invariance is not quite holding up. These deviations in intrinsic mass (not to be confused with the relativistic mass increase) and charge occur not only in the presence of very strong electromagnetic fields such as near an atomic nucleus, but also as the speed of the particle increases, meaning that the deviation from Lorentz invariance actually gets worse with increasing speed. Which is exactly what one would expect with the analogy to a material medium given above. One might wonder that perhaps Feynman's cavalier attitude to the mathematics in that instance has obscured something more fundamental. The fact that subsequent quantum field theories have followed the same pattern may have made this obscurity even worse.

General relativity also gives indications that Lorentz invariance should only be taken as an approximation. It is stated by the theory that in real curved space with real bodies inducing their own spacetime curvature, Minkowski space cannot exactly hold, in other words, Lorentz invariance does not exactly hold in real curved space. General relativity also seems to give a similar result as quantum field theory in that that deviations from Lorentz invariance get worse with increasing speed.

So what does this all mean? If Lorentz invariance can be shown to not exactly hold, then it is indeed likely that all of its other predictions are approximations as well, that in particular its prediction that physical objects cannot move faster than the speed of light is an approximation, and that at high enough energies, it is possible to go faster than c. I know, I know, this is all highly speculative, but then again, it seems that this doctrine of Lorentz invariance has reached the status of dogma among scientists, and anyone who questions its "absolute truth" is immediately labeled as a crackpot propagating heresy and any possibly valid arguments that might have been made are discarded solely on that basis. This is not the way science progresses.

The original source for much of this wu (which I have paraphrased and summarized) comes from the discussion in, "Experiments Poke Holes in Quantum Physics". See especially postings written by rgclark. The original Slashdot article had to do with the anomalous measurements of the muon magnetic moment that cannot be derived from modern theory, and could be further evidence that the Standard Model is invalid, and that the Lorentz invariance it takes for granted cannot be perfectly accurate.

And by the way, going faster than the speed of light does not necessarily imply a violation of causality: it could be that there is a special inertial frame of reference and that the principle of relativity needs to be abandoned, yet another idea considered heretical by most physicists.

Update: Some Australian researchers from the University of New South Wales have today (August 7, 2002) announced that they have detected some deviations in the value of the fine structure constant while observing light from a distant quasar 12 billion light years away, meaning that the light was generated only a short time after the creation of the universe. The value of α that they obtained was slightly higher than the traditionally measured one. Since the fine structure constant depends both on the electronic charge and on the speed of light, it could mean that either the value of the elementary charge has increased since the birth of the universe, or the speed of light was slower. Other observations they made rule out the possibility that elementary charge has changed as it would violate the Second Law of Thermodynamics. This could be construed as further possible evidence that Lorentz invariance is inexact. It seems the fine structure constant node already has some wu's about related discoveries. The article is:

One aspect of relativity that used to bug me was a thought experiment that I came up with similar to the one ariels describes above. I node it here mainly so that I don't feel like I've completely wasted my time in thinking about it for so long:

Imagine a lighthouse situated at a given distance from a wall of infinite length. At t = 0, the beam of light is perpendicular to the wall.

  L                                               angle = 0

The beam then begins to rotate, sending the point of light made by the beam along the wall.
  |   /      ~         _  -
  |  /    ~      _  -
  | /  ~   _  - 
  |/~_  -
  L                                    angle = 30, 45, 60...

As the above diagram shows, the point where the beam of light hits the wall begins to travel faster and faster, even though the rate at which the beam rotates is constant. The reason for this is that the distance travelled by the point of light is calculated using the tangent function, which approaches infiniti as an angle approaches 90 degrees. Eventually, as the beam of light becomes almost parallel to the wall, the speed of the little point of light where the beam hits the wall should also approach infiniti, and therefore appear to be moving faster than light along the wall, right? Well, not really. In fact, the photons that make up the beam of light are only travelling at the speed of light themselves, which affects when they actually hit the wall. The photons leaving the lighthouse are therefore spread out in an ever-expanding spiral:
              *                            *
                 *                           *
*                  *                          *
--*---------  ------*------------  -----------*------------------
   *                *                         *
L*            L    *               L         *
               * *                 *       *
                                      * *

So how do we figure out how fast the point of light is moving? Well, like all good scientists, we substitute a simpler model because we're lazy. Imagine instead of a rotating beam of light, we release a single burst of light in all directions at t = 0. In this example, the point of light will certainly travel no slower than in the previous example, as all of the photons will be released at the same time, instead of having to wait until the lighthouse has rotated. The model should now look like this (dubious ASCII skills notwithstanding):
            *                                      *
                 *                                   *
 *                  *                                 *
    *                *                                 *
------*---  ----------*--------  -----------------------*---
       *               *                                *
 L     *    L          *         L                      *
       *               *                                *
      *               *                                 *
    *                *                                 *
 *                 *                                  *
As the third figure shows, eventually the point of light on the wall will be travelling at about the same speed as the burst that created it - namely, at the speed of light - but no faster.

That said, it should be possible to create a point of light that appears to move faster than the speed of light - if the lighthouse beam began parallel to the wall and rotated so that the beam moved in the opposite direction from that of the first example, the point of light created by the beam should appear to move faster than light (and indeed, at a theoretically unbounded speed). Of course, to put this into practice you would need an infinitely long wall1, but given that it's simply a matter of getting photons to strike specific points at specific times, it wouldn't be that hard to kluge something similar.

1ariels points out that the infinitely long wall is only necessary if we want the point of light to move infinitely fast - in order to go faster than light, a really, really, REALLY long wall would suffice.

Some of the writeup above refer to things that do, in fact, move faster than light. Moreover, there's nothing wrong as far as physics is concerned.

In fact, there's a whole bunch of 'things' that are allowed to go faster than light, for example:

  • Marquee lights - like in Las Vegas, if you had a sufficiently large array of lightbulbs, you can make the 'moving lights' move faster than the speed of light to any arbitrary observer. Nothing is actually moving faster than the speed of light here, but if you calculate how fast an object would need to move to 'keep up' with the lightbulbs, it can be any arbitrary speed.
  • the intersection point in a pair of scissors, for instance - the point on a pair of scissors that do the cutting. If you take a sufficiently large pair of scissors, and close them sufficiently quickly, the movement of the point can move faster than the speed of light. Once again, there's nothing actually moving here.
  • phase changes - It's hard to see, but when something like water freezes, it's possible to observe the changing of liquid to solid moving accross medium. This phase change can move faster than light, but once again, nothing is actually moving faster than the speed of light, just the change in phase is moving.

As long as there are no 'particles' moving faster than the speed of light, and as long as there's no way you can use the moving thing to transmit information faster than the speed of light, a 'thing' can go faster than the speed of light.

I seem to have read somewhere that some things could move faster than the speed of light. It was said that the imaginary point where the two blades meet in a pair of scissors can travel at speeds faster than light, given a sufficiently long pair of scissors, even if the individual particles that constitute the mass of the scissors don't approach that speed.

When you close a pair of scissors, the aforementioned imaginary point travels the length of the scissors in a certain amount of time (the exact amount of time you take to close the scissors). The moment when the point reaches the pointy end of the scissors could be defined as the moment the scissors are completely closed; the moment the two blades align at their pointy end.

Now imagine we have a pair of scissors that are roughly 744,000 miles long and slightly open. They don't have to be uber-large, just uber-long. We'll say the fulcrum is at the exact center of their length, at 372,000 miles from either end. Now, Alice and Bob synchronize their watches and Alice stands at the rounded end of the scissors, with Bob making a short journey and manning the pointy end. Let's have Alice close the scissors, starting at precisely noon. What's more, lets have her do it naturally, taking only a quarter of a second to fully close them. Let's have Bob observe the pointy end and take down the time when they are fully closed. After the experiment, Alice and Bob will meet somewhere and compare their observed times.

So you might say that Alice started closing the scissors at 12:00:00.00 and Bob saw his end of the scissors close at 12:00:00.25, meaning that the imaginary point traveled the full 372,000 miles from the fulcrum to the pointy end in only a quarter of a second. The speed of light in a vacuum is roughly 186,000 miles/sec, so you might say that the point traveled at eight (8) times the speed of light. If you did say those things... you obviously weren't there when Alice and Bob compared their times.

See, the kicker is this: Information cannot travel faster than light. Period. If Bob is standing on the pointy end of this pair of scissors, he won't actually witness the closing at the same moment as Alice. Why is this? We must ask ourselves how the pointy end of the scissors knows when the other end has been closed? The atoms in the scissor material bump into one another conveying the energy along its length via a compression wave, much like the balls in Newton's Cradle. This compression wave of particles can only travel at the speed of SOUND in the given medium, likely steel if that's what our scissors are constructed of. The speed of sound in steel, depending on the exact alloy, is roughly 12,300 miles per HOUR. So when Alice closes the scissors, it's going to be about 60.5 hours before Bob knows it, and consequently, 30 hours and 15 minutes between the time that the little imaginary point left the fulcrum and made it to Bob. The speed of the compression wave in a solid is a function of the elasticity of the solid. With rubber scissors, it will take even longer for Bob to get closure.

The concept gets even weirder when you make the scissors longer. For a pair of steel scissors that are seven light years long, it will be 381,554 years from the time force is applied until the pointy end actually closes. That little point, whether the individual particles of the scissors moved uber-fast or not, cannot move faster than light. Hooray physics!

Update: Many thanks to Santo for correcting my originally incorrect assumptions and pointing me in the right direction concerning compression waves.

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