Lisa: There’s no air in space!
Homer: But there’s an Air in Space Museum!
An astronomer was giving a lecture on the sun, and finished by saying, “And in four billion years, the sun will expand into a red giant star, consuming the planets Mercury and Venus, and boiling Earth’s oceans, turning it into a barren waste.”
A panicked voice from the audience cries out, “Did you say four million years?”
The astronomer corrects him, with “No, sir, I said four billion.”
The voice from the audience, “Thank God! I thought you said four million!”
My three-year-old once asked me what stars were, and I (not a scientist) said, “They’re enormous balls of burning gas.” He scrunched up his nose and said, “Gas? You mean like farts?”
In the equation E=mc2 c is the speed of light, and you multiply by it, correct? Forgive me for asking but what does the speed of light have to do with matter and energy. It would seem the speed of light is woven into the basic fabric of all matter and energy? Is this correct? If so it’s very, very strange!
It’s more accurate to say that c is the inherent speed built into the laws of physics, and the laws of physics state that anything massless must travel at that speed. Since photons appear to be massless, they travel at that speed, but it’s not a property of light specifically, and in fact if it turns out that light isn’t completely massless after all, that would imply that it doesn’t quite travel at c, either.
Consider someone dropping a bullet into your hand from their fingers, vs. someone shooting it at you. The impact of the latter is increased by its kinetic energy, which is a product of its velocity.
Well, the rest mass of any matter is equivalent to its kinetic energy, and the velocity in question happens, for the reasons Chronos alludes to, to be c, the speed of electromagnetic radiation in a vacuum.
As an interesting aside, the c was originally derived from the Latin word “celeritas” meaning swiftness or speed.
Considering that the speed of light is approximately 186,000 miles per second, the designation seems an apt one.