So whatever that last term is () it’s also conserved (as long as you don’t change your own speed). Could this whole thing (thought Einstein) be the energy of the object in question, divided by c? And, since c is a constant, energy divided by c is also conserved. Notice that the energy and momentum here are not the energy and momentum: and .This only has noticeable effects at extremely high speeds, and at lower speeds they look like: and , which is what you’d hope for.If you have a vector (x,y,z), then it’s length is denoted by ““. When relativity came along, time suddenly became an important fourth component: (x,y,z,t).

” Why is it that the only part of the energy that anyone ever noticed was ? Up until Einstein that fastest things around were bullets moving at about the speed of sound.

“Spacetime rotations” (changing your own speed) are often called “Lorentz boosts“, by people who don’t feel like being clearly understood.

You can prove that the spacetime interval is invariant based only on the speed of light being the same to everyone.

Take everything that could have anything to do with the question (any speeds, densities, sizes, etc.) and put them together so that the units line up correctly.

There’s an excellent example in this old post about poo.

” Why is it that the only part of the energy that anyone ever noticed was ? Up until Einstein that fastest things around were bullets moving at about the speed of sound.“Spacetime rotations” (changing your own speed) are often called “Lorentz boosts“, by people who don’t feel like being clearly understood.You can prove that the spacetime interval is invariant based only on the speed of light being the same to everyone.Take everything that could have anything to do with the question (any speeds, densities, sizes, etc.) and put them together so that the units line up correctly.There’s an excellent example in this old post about poo.If you take a stick and just turn it, then of course it stays the same length.