Howtosignalprocessing
The idea of a speed limit comes from two predictions of the theory, that inertia increases towards infinite as velocity approaches light speed and that causality, the succession of cause and effect, is violated if we could signal at speeds above the speed of light.
- Is causality limited by the speed of light?
- What if the speed of causality was infinite?
- Why is there a cosmic speed limit?
- What is the speed of causality?
Is causality limited by the speed of light?
Similarly, a cause cannot have an effect outside its front (future) light cone. These restrictions are consistent with the constraint that mass and energy that act as causal influences cannot travel faster than the speed of light and/or backwards in time.
What if the speed of causality was infinite?
If the speed of light was infinite, all points in the universe would be able to communicate with each other instantaneously.
Why is there a cosmic speed limit?
Nothing can travel faster than 300,000 kilometers per second (186,000 miles per second). Only massless particles, including photons, which make up light, can travel at that speed. It's impossible to accelerate any material object up to the speed of light because it would take an infinite amount of energy to do so.
What is the speed of causality?
As Matt explains, the speed of light should really be called the speed of causality. You can think of causality in relation to a concept known as the spacetime interval, which states that causal connections are the only order of events that all observers, from wherever they're positioned in the Universe, can agree on.
