Top Document: [sci.astro] Astrophysics (Astronomy Frequently Asked Questions) (4/9) Previous Document: D.09 How can gravity escape from a black hole? Next Document: D.11 What are magnetic monopoles? Are they real? See reader questions & answers on this topic!  Help others by sharing your knowledge See also the sci.physics FAQ part 4: ftp://rtfm.mit.edu/pub/usenetbyhierarchy/sci/physics/ sci.physics_Frequently_Asked_Questions_(4_4)] Tachyons are theoretical particles that always travel faster than light. Tachy meaning "swift." There is a formula that relates mass to speed in the special theory of relativity: m = m0 / SQR(1  v^2/c^2) where m = energy divided by c^2 (sometimes called "relativistic mass") m0 = rest mass v = velocity of mass relative to you c = velocity of light (constant in all frames of reference) So, as you see an object moving faster and faster, its mass increases. A simple experiment with electrons in a vacuum tube can convince you that mass increases in this way. So you get something like: v/c m/m0 0.0 1.000 .2 1.021 .4 1.091 .6 1.250 .8 1.667 .9 2.294 .95 3.203 .99 7.089 .995 10.013 .999 22.366 1.000 infinity This led Einstein and others to conclude that it was impossible for any material object to travel at or beyond the speed of light. Because as you increase speed mass increases. With increased mass, there's a requirement for increased energy to accelerate the mass. In the end, an infinite amount of energy is needed to move any object *at* the speed of light. Nothing would move you faster than the speed of light, according to this type of analysis. But, some researchers noted that light has no trouble moving at the speed of light. Furthermore, objects with mass have no trouble converting to light. Light has no trouble converting to objects with mass. So, you have tardyons and photons. Tardy meaning slow. These classes of objects can easily be converted into one another. Now, in terms of the equation given above, if you start out with *any* mass you are constrained to moving less than the speed of light. If you start out with zero mass, you stay at zero mass. This describes the situation with respect to photons. You have zero over zero, and end up with zero.... But, what if you started out faster than the speed of light? Then the equation above would give you an imaginary mass, since v^2 / c^2 would be greater than 1 and that would be subtracted from 1 to produce a negative number. Then you'd take the square root of the negative number and end up with an imaginary number. So, normal matter moving faster than the speed of light ends up with imaginary mass, whatever that may be. Imaginary mass travelling faster than the speed of light would show up as regular mass to an observer at rest. v/c m/m0 (m/m0)*i infinity 0+0.000i 0.000 1,000 00.001i 0.001 100 00.010i 0.010 10 00.101i 0.101 8 00.126i 0.126 6 00.169i 0.169 4 00.258i 0.258 2 00.577i 0.577 1.5 01.118i 1.118 1.1 02.182i 2.182 1.05 03.123i 3.123 1.01 07.053i 7.053 1.000 0inf*i infinity So, if there was such a thing as imaginary mass, it would look like normal mass but it would always travel *faster* than c, the speed of light. When it lost energy it would move faster. When it gained energy it would move slower. So, in addition to tardyons and photons, there might exist tachyons. Description Tardyon Photon Tachyon Gain energy faster c slower Lose energy slower c faster Zero energy rest c infinity Infinite energy c c c Now, do tachyons exist? If tachyons exist they can easily be detected by the presence of Cerenkov radiation in a vacuum. Cerenkov radiation is radiation emitted when a charged particle travels through a medium at a speed greater than the velocity of light in the medium. This occurs when the refractive index of the medium is high. Cerenkov radiation is like the bow wave of a boat, or the shock wave of a supersonic airplane. Photons bunch up in front of the tachyon and they're radiated away at an angle determined by the speed of the tachyon. Cerenkov detectors are useful in atomic physics for determining the speed of particles moving through a medium. Light slows as it passes through a medium. That's what's responsible for optical effects. There's nothing mysterious about Cerenkov radiation in a medium. So, folks know how to make an operate Cerenkov detectors because they're a useful speedometer when you're working with subatomic particles Now, there have been a few studies looking for Cerenkov radiation in a vacuum. This would indicated the reality of tachyons. Cerenkov radiation has never been detected in vacuum. So, most people believe that tachyons don't exist. User Contributions:1 xoran todorovic Jun 23, 2018 @ 2:02 am The Theoretic Research of Tachyons with Real Mass:Tachyon Transformation Matrix, Tachyon Oscillations, and Measuring Tachyon Velocity: published in International Journal of High Energy Physics,June 11,2018. 2 zoran todorovic Jun 23, 2018 @ 2:02 am The Theoretic Research of Tachyons with Real Mass:Tachyon Transformation Matrix, Tachyon Oscillations, and Measuring Tachyon Velocity: published in International Journal of High Energy Physics,June 11,2018. Comment about this article, ask questions, or add new information about this topic:Top Document: [sci.astro] Astrophysics (Astronomy Frequently Asked Questions) (4/9) Previous Document: D.09 How can gravity escape from a black hole? Next Document: D.11 What are magnetic monopoles? Are they real? 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