Active Reading Solution: The High Energy Limit

It's not obvious what happens to that formula as E→∞, is it? But it's much clearer to look at it the other way; you can readily see that as v→c^-, that makes E→∞.

So as you add more and more energy—that is, you keep exerting force to accelerate an object—its speed does not approach infinity as it would in classical dynamics. Rather, its speed asymptotically approaches c.

We see this in particle accelerators in real life, where adding more and more kinetic energy accelerates particles to very high percentages of the speed of light, but never past.