A physicist says The Flash must have these extra superpowers or he'd die

Barry Allen was just a shy Central City crime scene investigator. Until, that is, a particle accelerator accident transformed him into a super-powerful force: The Flash.

In the hit TV show "The Flash," which recently returned for its second season on the CW, Allen (played by actor Grant Gustin) can reach blinding speed in the blink of an eye. He applies this speed to bend the rules of physics, leaving sonic booms and shattered glass in his wake as he scales buildings, hydroplanes across water, and punches faster than the speed of sound.

It's the kind of speed that makes dodging bullets look boring and passé. Assuming his superhero alter-ego, he seeks out other metahumans transformed by the accident and clashes with the less-than-lawful ones using his mind-bending feats of speed.

But there must be more to The Flash's superpowers than velocity — otherwise Allen would be torn apart by brutal high-speed physics in a ball of magnetized static electricity (more on that in a moment).

To figure out how Allen might actually survive, Tech Insider spoke to James Kakalios, a physicist at the University of Minnesota and author of "The Physics of Superheroes." The Flash is one of Kakalios' favorite superheroes and he's a big fan of the show.

Kakalios gave us some insight into the extra powers that The Flash would need to make superspeed work. (And obviously we're suspending our disbelief pretty heavily for this, since we all know the show is a work of fiction.)

Body-mashing acceleration (and superhuman healing)

It's Allen's acceleration and deceleration abilities that really impress Kakalios.

The Flash isn't just fast, he's instantly fast. He goes from standing still to blistering speed without any noticeable delay. Nothing in the real world accelerates that quickly. Even a cheetah has to take a few strides to get up to sprinting speed and a Lamborghini a few seconds of engine time to reach 60 mph.

But Allen can accelerate at a rate that would break legs, smash organs against the inside of the rib cage, and generally wreck your body. Each stop would be like getting into a terrible car accident — although a supersonic plane crash might be more appropriate, in terms of speed and force.

And early on in the series, while still getting used to his superspeed, Allen smashes into things at speeds above 200 mph. Collisions like this do not do a human body good.

"It would pretty much spoil your whole day," Kakalios joked.

Hence, his (overly convenient, in my opinion) superhealing power. Without it, The Flash wouldn't do much at all — he would have died after just one super sprint.

Superhuman reflexes

Just like Allen's body needs superhealing to make superspeed possible, his brain needs a major upgrade as well: Moving at superhuman speed requires superhuman reflexes.

The human body already has fast reflexes. We can process information in mere milliseconds, and our instinctual reactions often happen before we even realize we're shielding our faces or ducking for cover.

Kakalios mentions a sudden stop in stop-and-go traffic as an example: You're jolted into alertness, adrenaline surges, and you brace yourself for a collision, all within a single second.

But Allen's reflexes would have to be unfathomably quick, considering the guy is constantly sprinting in and out of moving traffic as a blur.

"The Flash obviously has a faster clock in his brain," Kakalios said. "He's moving at such speeds that if he had normal reaction times, he would be colliding into things."

Superhuman eyesight

And these reflexes would mean nothing if his eyes weren't super-powered themselves, providing the visual input needed to make split-second decisions (though "split-second" may be an understatement with this kind of speed).

Allen would need faster eyes to see all the obstacles coming at him at superspeed. And the way he looks to us at high-speed reveals why stock human eyes wouldn't cut it.

"The Flash looks like a blur because the brain can’t process the optical signal that fast," Kakalios explained.

The kind of acceleration and deceleration the Flash experiences also cuts off circulation to the eyeballs. As test pilots in the space race undergoing G-force tests learned, this blinds you (at best, temporarily).

Superhuman anti-static cling

We also need to look at the powerful electrical charge that Allen would build up while running.

Friction between the ground and our feet is fundamental to walking and running, but it can also generate a static charge. And if enough builds up, it's discharged in a little static shock — a surprising jolt, but not dangerous or painful.

The massive amounts of friction between the ground and the Flash's feet would generate a ton of electricity. So much, Kakalios suggests, that all that electricity running through his body would create a magnetic field, "pulling everything magnetic in his wake."

At superspeed, the Flash would turn into a weaponized magnet, dragging cars, uprooting streetlights, and turning small metal objects into bullets rocketing behind him. The Flash couldn't keep himself from wrecking infrastructure and smashing bystanders with debris, let alone keep Central City safe from metahumans.

Science as an Easter egg

Again, this is a fictional character in a fictional universe — but the CW's "The Flash" is actually pretty good when it comes to scientific accuracy. At least they changed The Flash's power origins to a particle accelerator mishap, instead of the original, and harmless, "hard water" spill. (They may have meant "heavy water," used in nuclear reactors and bombs.)

Kakalios is willing to forgive most superhero science mistakes, though. But he says when producers get it right, it's a nice touch.

"I don't watch the show with a pad of paper and calculator," he said. "If they get the science right, it's like an Easter egg hidden in the story."

Besides, if "The Flash" followed all the rules of physics to a T, Barry Allen would be reduced to a useless, blind pile of static electricity and broken bones.

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