There is a wonderful book on Cosmology: Its called Cosmology, the Science of the Universe by Edward Harrison. It explains difficult concepts very concisely. In the chapter on Special Relativity I came across the following quote:
“Brief happenings are events denoted by points in spacetime diagrams. Things that endure, such as observers, are world lines extending from the past to the future. An observer receives light signals that come in from the past and transmits light signals that go out into the future.”
What an incredible image of us existing on the brink between future and past. Any information that comes at us from the environment, comes from the past. And, anything we transmit, a word, an action, our image, transmits into the future. Even as a thought makes its journey from our brain to our mouth, it’s coming from the past to be transmitted to the future. Instead of time being either a river we are wading in, or an unfolding dimension propagating along with space, we find ourselves at a nexus. Each and every piece of matter is located at a similar junction. This image/idea is somehow haunting and visceral.
But, what about energy? Is it different for energy because of the speed of light? Harrison says that “the fact that light moves at speed c, and c is a speed limit for all particles moving at high energy, is not in itself greatly astonishing. It is the constancy of c for all observers, even for observers moving in opposite directions at high-speed, that astonishes.” Light travels through spacetime, subject to the laws of physics, but it doesn’t receive and transmit information, it is information, strange.
