They Say Running can be Beneficial to Your Health

One of the many, many things I don't understand about physics is the idea of time moving more slowly as you go faster. That whole bit about how, if you traveled to the nearest star and back at the speed of light, it would be 8 years for you, but some thousands of years for people back on Earth. Doesn't make any sense to me at all.

But, if I'm accepting that's true, and for the purposes of this post I might as well, would that mean the various Flashes should live an exceptionally long time, at least from their friends' perspectives?

There's a lot of DC heroes that seem to live a long time. Superman's living in the heart of the Sun for however long, Martian Manhunter's still alive in the 853rd Century, The Shade is still around in the 30th, at bare minimum. There's always a damn Hawkman around, and Dr. Fate's helmet.

The Flashes, though, they time travel a lot, or get lost in the Speed Force. But it feels like we're more likely to see them aging faster because of some side effect of all the super-speed, rather than slower. (Maybe I'm just thinking of Barry Allen withering away in Crisis on the Infinite Earths.) But if they spend a bunch of time moving at near-light speeds, even only for a few seconds at a time, then much more time than that should have passed for everyone else when Barry or Wally slow back down again.

This seems like it would negate the advantage of super-speed now that I think of it. You got someplace instantaneously, but somehow a whole bunch of time still passed. I'm probably thinking of it cock-eyed.