Speeds greater than the speed of light

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SUMMARY

The discussion centers on the concept of superluminal speeds and their implications for relativity and causality. Participants argue that while theoretical calculations may suggest speeds greater than light, such phenomena cannot transmit information, thereby preserving the universal constant 'c' as the speed limit for communication. The conversation highlights the paradoxes that arise from accepting superluminal communication, including the rejection of fundamental principles such as causality and the uniformity of physical laws across inertial frames. Key references include Nick Herbert's book "FASTER THAN LIGHT" and the article by Mattingly on Lorentz invariance.

PREREQUISITES
  • Understanding of Einstein's theory of relativity
  • Familiarity with Maxwell's equations
  • Knowledge of Lorentz invariance and its implications
  • Basic concepts of causality in physics
NEXT STEPS
  • Research the implications of superluminal communication on causality and free will
  • Study the theories surrounding Lorentz invariance violations
  • Examine the content of "FASTER THAN LIGHT" by Nick Herbert for examples of superluminal phenomena
  • Explore the Free Will Theorem by Conway and Kochen for insights on determinism and free will in quantum mechanics
USEFUL FOR

Physicists, students of theoretical physics, and anyone interested in the implications of superluminal speeds on relativity and causality.

  • #91
I'm not sure if my answer would fall under this category. I want to introduce an idea of transmitting information at a speed faster than the speed of light. I am sure somebody has already thought of this...? Basically all you need is a rod which would exceed the distance of the speed that the light travels, say in an hour (just for practical applications). Pushing that rod at one end will result in the rod being moved at the other end instantly, with zero delay. A principal of a Morse code can be applied - a rod can be pushing a button on the other end, thus transmitting information at a speed faster than the speed of light. Obviously there can be a number of problems with this - the rod can simply be pulled by a gravity of a passing planet, or be hit by a meteorite, etc... But the fact of the matter is that, information can be transmitted at a speed greater than the speed of light.
 
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  • #92
No, it can't. Pushing on a rod transmits information at the speed of sound in that material, which is always much less than the speed of light. And yes, your idea has been thought of many many many times on this forum already.
 
  • #93
escogido said:
I'm not sure if my answer would fall under this category. I want to introduce an idea of transmitting information at a speed faster than the speed of light. I am sure somebody has already thought of this...? Basically all you need is a rod which would exceed the distance of the speed that the light travels, say in an hour (just for practical applications). Pushing that rod at one end will result in the rod being moved at the other end instantly, with zero delay. A principal of a Morse code can be applied - a rod can be pushing a button on the other end, thus transmitting information at a speed faster than the speed of light. Obviously there can be a number of problems with this - the rod can simply be pulled by a gravity of a passing planet, or be hit by a meteorite, etc... But the fact of the matter is that, information can be transmitted at a speed greater than the speed of light.
Turns out this idea doesn't work because there are no perfectly rigid objects in relativity (solid objects are just collections of atoms held together be the electromagnetic force, and electromagnetic interactions travel at light speed). If you push one end, it creates a compression wave that travels along the rod at the speed of sound in the material, the other end doesn't move until the wave reaches it. See here for more info:

http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/FTL.html#4
 

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