Physics in a Flash

The Flash was born in 1940 with that opening declaration. Jay Garrick had a nifty metal helmet with wings on the side and he could run really really really fast. Not fast enough to propel sales of his comic book, however. He vanished in less than a decade.

Fear not, speed fans! The adventures of Jay Garrick inspired Barry Allen to become The Flash after he coincidentally spilled just the right set of chemicals on himself when a lightning bolt crashed through the window, allowing him to run really really fast. Yeah that seems a bit improbable. But, it turns out it isn’t improbable at all! Just three years later, young Wally West was visiting his idol The Flash, when a lightning bolt came streaking through the window causing the exact same set of chemicals to spill on Wally! Kid Flash is born!

More years, more Flashes. They come and go. But, they all run really really fast!

Which presents certain…problems.

The Laws of Physics catch up to the Flash. You see, running faster than the speed of light is, well, a might bit difficult. Now, in Superhero Land, you do have to suspend disbelief a bit—people can do all sorts of impossible things in comic books. But Physics plays a really big role in the development of the Flash over the years. This is really apparent in The Flash: A Celebration of 75 Years. At various points you can see the writers realize that the laws of physics might have some weird effects on a guy who can run really fast.

First off, as Einstein (a real person! Not a comic book person!) showed, as something speeds up, it acquire more mass. If it moves at the speed of light, it would have infinite mass, which is a lot of mass. A fist, for example, moving at something close to the speed of light would pack a rather powerful punch. The Flash isn’t strong, but he is fast. Theoretically, if he swings his fist fast enough, he can hit harder than anything else ever could. One punch and he could lay out even Superman!

But, unfortunately, while the mass is rising to infinity, the energy required to move the object is also rising to infinity. So, it takes a lot of energy to move really really fast. To do so requires a source of energy. The Flash would need to eat a lot, a whole lot, to generate that much energy. (This is actually a plot line in one of story lines from the 1980s.)

But, wait, there is even more physics! As The Flash moves faster, time slows down. So, the Flash will age slower than all those slower mortals as long as he keeps running really fast. Move faster than the speed of light, and time goes all wonky (that is the technical term) in the governing equation—so who knows what happens? Maybe…time travel! The flash travels through time a lot. He even has special time travel treadmill because, you know, trying to run faster than light on the earth means you’ll run into something sooner or later.

But wait, if you can move really, really fast, then your molecules must be moving really fast too, right? So what if you just vibrated all your molecules really fast? You could take advantage of all the empty space between your molecules and between the molecules in a solid object (like, say the bars in a jail cell), and you could walk though solid objects. Quantum Tunneling!

Oh, and if you are running at the speed of light (or even faster) you are really going to need to be thinking really fast.

And, by this point in the list of all the nifty things The Flash can do, you realize it might be a bit hard to generate that much energy even if you do eat a lot. So, along comes the Speed Force, which is some mystical energy field that screams in huge Neon Letters “The writers just gave up trying to explain all this.”

And at that moment, all the excitement of the physics of The Flash dies. He cheats. He has the Speed Force and his time traveling treadmill and so has pretty much unlimited power to wander through time really fast and do whatever he wants to do. So what started out as a nifty little idea of a guy who can run really fast ending up meeting the laws of Physics which led to a guy whose powers seem to know no bounds because all he has to do is run really fast on his treadmill and go back in time and fix whatever mistake he just made.

Is there a lesson here? Of course there is: Physics is amazingly interesting. Lots of kids learned about Einstein and the theory of relativity from reading The Flash. You know all those people who complain that kids don’t like learning physics? Maybe they should read comic books first and then work backwards to figure out the physics behind it all. It is not the worst educational idea out there. It might just work.