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SYFY WIRE Science Behind the Fiction

Sonic's gotta go fast. Unfortunately, science says it would tear his body apart IRL

By Cassidy Ward
Sonic the Hedgehog music video

Sonic the Hedgehog is one of the most iconic characters in the video game lexicon. He's been around for almost 30 years, giving fans plenty of time to speculate about his true nature. Lots of thought (maybe too much, but who are we to judge?) has gone into just how fast he truly is.

The folks over at Game Theory spent some time calculating just how fast Sonic is in his various game titles and the results are... underwhelming.

According to their calculations, the Blue Bolt clocks in at just about 80 feet per second, on his best day. That's a far cry from the bill of goods we've all been sold. The word "sonic" is in his name, after all.

To be fair, these calculations stuck strictly to what can be seen during gameplay and that is, understandably, restricted in order to make the game playable. If Sonic were truly zipping around faster than the speed of sound, it would have a pretty detrimental effect on gameplay.

If we allow ourselves to suspend our disbelief, we could trust Sonic Unleaded's in-game speed meters, which have clocked Sonic at up to 2,500 miles per hour. We might also reference the manual for Sonic Adventure DX, which boasts a top speed of 3,840 miles per hour. There are, of course, also the light-speed shoes to consider.

The question of Sonic's top speed is seemingly unanswerable. Even the in-game answers don't agree with one another and that's to say nothing about the cartoons or comics.

And, to be honest, enough has been said about Sonic's speed. What we're interested in is the consequences of traveling at those speeds. And with his live-action debut finally hitting theaters this weekend, what better time to find out?


Sonic's primary concern is not his speed, but his acceleration. Once at speed, things level out. The G-forces level to 1 once you stop gaining speed. That's why astronauts on the space station don't splatter against the walls, despite traveling at more than 17,000 miles per hour while inside it.

The forces inside your body when accelerating are the same as if you're already moving fast and suddenly stop. Your body doesn't care whether you're coming or going — it's all about changes in momentum.

For our purposes, we'll assume Sonic's top speed is 767 miles per hour, the speed of sound. That's fast. Faster than any creature on Earth can go without the aid of technology. Despite common knowledge, the animal speed record is not held by the cheetah. While it's land-speed of 75 miles per hour is impressive, the animal speed record is actually held by the Peregrine Falcon with a maximum diving speed of 242 miles per hour, fast enough to swoop down from above and punch other birds out of the sky.

Sonic's speed is more than three times as fast as that, and he accelerates to the speed of sound almost immediately. Therein lies the trouble. The G-forces during that sort of acceleration would wreak all sorts of havoc on a body.

Assuming a zero-to-sound barrier time of 1 second, Sonic would experience more than 34 G-forces on his body, albeit for a short period of time. The impact of those sorts of forces are many and none of them are good.

First, he'd experience "grayout." He'd lose the ability to process color as blood flow to his eyes diminished. Ultimately, he'd blackout as his blood failed to replenish the sensitive cells in his eyes. Then he'd pass out.

Short of some unusual circulatory system, Sonic's heart wouldn't be able to combat the force of acceleration and would fail to supply blood to his brain.

Ironically, slowing down the acceleration makes the situation worse. Doubling the amount of time it takes him to hit Mach 1 still results in G-forces almost double what a human being can stand without losing consciousness while doubling the amount of time he'd experience those forces.

What's worse, if Sonic were to lose consciousness while running at the speed of sound, he'd very likely collide with a stationary object and immediately come to rest. When we crunch the numbers on a collision of that kind, we find that Sonic would suffer what we in the scientific community call "death."

The kinetic energy of a 35 kg object traveling at the speed of sound (343 m/s) comes in at 2,058,858 joules. For context, a one-ton wrecking ball dropped from a height of two meters, on a pendulum, reaches a maximum of 17,000 joules at the peak of its arc. Which is to say, if Sonic hit a building at full speed, it'd do a hell of a lot of damage and he would be a puddle of blue mush. Probably with a lot of red in it.

If Sonic were to come to a stop, at the mercy of an immovable object, he wouldn't even have the luxury of the one-second deceleration. The forces acting on his body would be immediate; his bones and organs would come into contact first with his skin, then with the outside world, at the speed of sound. Bones would break and organs would burst. He'd never have the chance to regain his sight because his eyes would no longer be tethered to his brain.

Speaking of eyes…


Though hedgehogs rely almost totally on their senses of sound and smell because their eyesight is terrible, let's assume that Sonic, clearly a talented hedgehog, has eyesight similar to a human being and that he's not blinded by his acceleration. Assuming he's running on a level plane (accounting for the curvature of the Earth), Sonic should be able to see objects his own size roughly two miles away.

Given his speed, he'd cover that distance in roughly 10 seconds. This would give him plenty of time to adjust for such an object and move out of its way.

The trouble comes in when he has to account for smaller objects, or for larger ones moving when he's closer to them.

The reaction time (the time needed for light to enter your eye, hit your brain, and elicit a response from your muscles) is about .2 seconds.

At the speed of sound, Sonic would be traveling approximately 225 feet while his brain was processing the visual input in front of him. Even accounting for the brain's lag-correction, any changes to the landscape within the first 100 feet or so in front of Sonic would be invisible to him. He'd come into contact with any moving object before his brain ever had a chance to notice.

No matter how fast you run, you can't outrun the speed of cognitive processing. In order for Sonic to stay alive with the sort of speed he's at, he'd need a whole host of other superpowers just to prevent himself from becoming mush the first time he turned on the afterburners.

Sonic the Hedgehog


The next best thing (or worst, given the political climate) after his incredible speed is Sonic's penchant for collecting gold. Riches abound in Sonic's world and gold coins almost the size of his body are all over the place. Sonic swoops them up while he runs, tucking them into his… pockets (?) before continuing onward.

The in-game rings are about the size of Sonic's head. We'll assume a foot in diameter. Even if we're being conservative, we're talking about an amount of gold equal to a standard gold bar — about 400 ounces, or roughly 25 pounds. Just three of them would amount to Sonic carrying his weight in gold while running at Mach 1.

The number of rings he's able to carry, with no impact on his speed, is limited only by the number available in a given level. This raises a whole host of questions about his true top speed. Surely if he can maintain momentum while carrying thousands of pounds of gold, he could go faster without that burden.

In any event, carrying even a dozen rings would increase his total weight to five times standard.

In-game, if Sonic comes into contact with an enemy or an object (sometimes a sharpened spike, dear God), he has a moment of panic and spills his rings all over the place.

In reality, the above mentioned physical impacts would only be heightened. The gold would surely spread across the land at incredible speeds, but Sonic would never have the chance to collect them again.

It's lucky that Sonic hails from the planet Mobius, where the laws of physics are surely totally unrecognizable. Because the truth is, he wouldn't last a fraction of a second here on Earth. Despite all our warnings, you'll have a chance to see him in action on the big screen on February 14.