Īccording to Nemiroff, photonic booms could potentially be seen in NGC 2261, also known as Hubble's Variable Nebula: a fan-shaped cloud of gas and dust that is illuminated by a single star at its base. According to the statement from Michigan Tech, a light beam could be swept across an asteroid's surface "thousands of times per second, with each sweep forcing a harmless but telling photonic boom." Each boom would then be used to "reveal the size and surface features" of the asteroid. Measuring a photonic boom could reveal information about the object on which it appears. According to the statement, "details of the effect hinge on the interplay between the time it takes for a sweeping light beam to cross an object and the time it takes for the light beam to traverse the depth of the object." Therefore, if the moon were just a flat disc, a photonic boom could not be created across it. Rather than an infinite wall, a photonic boom would appear when a beam of light moves across a spherical surface with depth contours, like Earth's moon, Nemiroff said. Rosanne Di Stefano of the Harvard-Smithsonian Center for Astrophysics, added in the statement: "The concept, although not proven in practice, is quite intriguing," "Out in the cosmos, they last long enough to notice - but nobody has thought to look for them!" "Photonic booms happen around us quite frequently, but they are always too brief to notice," Nemiroff said in a statement from Michigan Technological University. Instead of a laser pointer, these photonic booms might be created by other bright sources of light like pulsars, which are collapsed stars that create very bright, steady beams of light. In the paper, Nemiroff argues that these photonic booms exist in nature. Nemiroff provided the technical details for this scenario in a paper that is now available on the preprint website. It is not a single photon traveling faster than the speed of light.) This creates a burst of light, which Nemiroff calls a "photonic boom" because it is similar to the sonic boom that occurs when an object exceeds the speed of sound and overtakes sound waves. (As with the laser pointer projected onto the ceiling, this is an illusion. One point of light is traveling more slowly than the speed of light, while the other appears to be moving faster.
In fact, the spot of light must always be in two places at once.īecause the photon must be in two places at once, Nemiroff explained, something very bizarre happens: Two points of light appear on the wall, moving in opposite directions - one away from you and one toward you. But it also can't be right next to you - it has to be at some point between you and infinity.īut according to Nemiroff, if you choose a finite point where the light should be, the beam must always be just beyond that point, one step closer to infinity.
At what point does the laser pointer intersect the wall? It can't be at infinity, because that would take infinite time. Turn your wrist so the laser pointer intersects the wall. Now, imagine you are shining the light parallel to an infinite wall. You don't see the laser dot projected anywhere because there is no end to this room. Now, imagine shining a laser pointer straight out into infinite space. This is the first part of Nemiroff's thought experiment. Each flash of light is an isolated event, and they only create the illusion of movement collectively. In theory, it would be possible to have a word move across the screen faster than the speed of light - because nothing has actually moved.
#Laser pulses travel faster than light series#
In reality, the word is created by a series of flashes from many individual, stationary lights. No single photon in the stream ever moves faster than the speed of light, but collectively, they can create the illusion of faster-than-light travel.Īnother way to understand this illusion is to imagine an electronic ticker tape, which creates the illusion of a word moving horizontally across the screen. Nemiroff's experiment doesn't break this physical law because the laser pointer produces a stream of photons, not a single photon. Einstein's theory of special relativity says it is impossible for an object (like a single photon of light) to look as though it is traveling faster than the speed of light.
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