To think about.Ginkgo wrote: ↑Fri Jun 26, 2015 6:19 amSystematic wrote:The speed of light is finite, therefore it would take a finite amount of energy to reach it.Ginkgo wrote: It doesn't. It is impossible to accelerate a mass to the speed of light. It wold require an infinite amount of energy to do so. This idea is probably related to a mathematical explanation, or logical outcome of such a scenario. It isn't possible.
This connection between energy and mass, known as mass-energy equivalence, was immortalized in Einstein’s equation E = mc2, where E stands for energy, m stands for mass and c is a constant (which happens to be equal to the speed of light). Actually, E = mc2 is just the simplest case scenario, that for a body or mass at rest. For a body in motion, with a velocity v, the equation becomes E = Einstein's Mass-energy equivalence equation. We have already seen that the Lorentz factor γ ≡ Lorentz Factor, so we can therefore also say that E = γmoc2 (where mo is the rest mass of the object). As can perhaps be reasonably easily deduced from these equations, as the velocity (v) approaches the speed of light (c), energy (E) approaches infinity, indicating that the body would in fact require an infinite amount of energy to accelerate to the speed of light. We can also see how (as mentioned in a previous section) the mass of a moving object becomes greater and greater as its velocity increases until, at the speed of light, it becomes infinite.
Taken from The Physics of the Universe.com
Velocity is relative. A object's velocity is only in relation to some other object. There is no, "absolute," velocity.
If object M is moving at a velocity 40% C (ninety percent of the speed of light) relative to object N, and, in the same direction, object N is moving at a velocity 40% C relative to P, what is the velocity of M relative to P? Won't it be 80% C (velocity of M plus the velocity of N)?
If object M is moving at a velocity 90% C (ninety percent of the speed of light) relative to object N, and, in the same direction, object N is moving at a velocity 90% C relative to P, what is the velocity of M relative to P? Won't it be 180% C (velocity of M plus the velocity of N)?