I spend a lot of time thinking about Einstein and his theories of General Reletivity and Special Reletivity. Both theories have significant impact on our lives regarding how we perceive the universe’s function. In SciFi we like to talk of Lightspeed travel, when in reality we should talk of super-luminescent travel, travel at the speed of light, and sub-luminescent travel. General Reletivity deals with sub-luminescent travel and Special Reletivity deals with the transcendence of the speed of light.
Einstein’s simple yet elegant summation of E=mrelc2 (Eo=moc2) is at once a masterpiece, yet hard to understand. It means that the total energy (E) of a system in motion is equal to its relative mass (mrel) times the speed of light squared. When a system is at rest, the total energy, rest energy (Eo), will be equal to the rest mass (mo) times the speed of light squared (c2).
However, the problem lies with the location of the observer. If multiple observers are outside of the system in question, with differing velocities regarding the observed mass, they will see the system in motion with differing relativistic total energies. The faster each independent observer goes regarding the observed system, the lower the observed relativistic energy of the system. When the observer is stationary, regarding the moving system, you will get a maximum comparison. An observer moving slower than the system under observation will report that the object has greater inertial energy compared to an observer going faster than the system, and an observer going the same speed will report rest energy for the system in motion.
If the observer is with the body, like with space travel in a ship of some sort, then the observer cannot conclude the mass is in motion relative to themselves. This is obvious, but I must point out again that the observer MUST be outside the system to observe correctly and the measurements are relative to the observer’s motion. So if you are in motion WITH the system you will have the same inertia as the system and thus the same relative mass. For maximum realization of inertial energy, the observer must be stationary regarding the system being investigated and be outside the system.
At rest, the system’s energy, referred to as the rest energy (Eo), is at its lowest, as the system speeds up, the acceleration adds inertial energy to the system which makes the matter seem heavier. We call this relative mass (mrel) and it will approach a maximum the closer to the speed of light an object gets. The object will never reach the speed of light, at least according to modern models, but it will get infinitely close thus the system’s mass will approach infinity.
According to Special Relativity, which deals with super-luminescent velocities, the system at the speed of light will undergo foreshortening and will appear to elongate. The foreshortening relative to a stationary observer will appear different to an observer in motion relative to the system being observed. The faster an observer moves regarding the system in question, the less evident the foreshortening will be. Foreshortening is because the matter of the system exists in three states simultaneously. Sub-luminescent, Lightspeed, and super-luminescent as different parts of the system undergo the ‘jump’ to super-luminescent velocity at different times.
The leading edge of the object is pushing through the light barrier and is again accelerating, now faster than Lightspeed, The middle of the system is right at the speed of light, an instantaneous barrier, akin to standing still, and is moving slower than the leading edge, but faster than the trailing edge of the system. At this point the system releases all the stored energy and the relative mass is again equal to the rest mass, like the object is momentarily stationary. The trailing edge will quickly catch up, but is still moving at sub-luminescent velocities and still filled with inertial energy.
To see this effect in action, watch any Star Trek episode from The Next Generation and just wait for the ship’s captain, Jon Luke Picard, to wave his hand and say his catch phrase ‘Make it so’ for the jump to super-luminescence. You will notice the clear foreshortening of the U.S.S. Enterprise as it goes through the leap as described above.