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Five Needlessly Inaccurate Sci-Fi Myths and Their Awesome Truths

by Timothy Johnson


These aren’t those times.


1. The Exploding Astronaut

Few things are as dramatic as a human body literally exploding or the threat of such calamity. After all, Scanners successfully spanned several decades to land on the Internet as one of the most-often used memes, and the film did it just by blowing up heads.

But when it comes to the vacuum of space, few sci-fi violations are as egregious as a human being literally blowing up from the pressure differential. It may seem plausible, but it just isn’t what would happen if a person were exposed to space.

Because of the elasticity of our tissues, there wouldn’t be a sudden outward push from the pressure inside our bodies. Our tissues would inflame, resulting in bruising, and our blood would boil (in the sense that it would develop gas bubbles, but not burn in our veins). The nitrogen in our blood would spontaneously become a gas, which could rupture small blood vessels.

But how do we know? Admittedly, much of this is theoretical, but NASA has Chamber A, in which it conducts a lot of vacuum-related experiments. And in 1966, Jim LeBlanc famously lost pressure in his suit while in a vacuum chamber and reported feeling the moisture on his tongue evaporating before he lost consciousness in 14 seconds.

Really, when it comes to space, the vacuum is the least of our worries, because we’d be dead before it stood any chance to kill us. For instance, no one has ever said they’ve heard it’s nice this time of year in space.

2. The Human Popsicle

After spontaneous explosion, it’s often alluring to the gore fanatic to think of the deep freeze of space and what would happen to a human being exposed to it. After all, deep space is roughly estimated to be about 2.7 Kelvin, which is very close to absolute zero. That’s cold! If we’re not going to blow up, we’ll probably instantly freeze in those temperatures, right? Not likely, and it’s because of the physics of heat transfer.

Why is a 70-degree spring day the best thing ever while 70-degree water is almost too cold to swim in? Heat transfer. Generally speaking, it is much easier for your body to transfer heat to another solid than a liquid. It transfers heat better to water than to air. Seeing a trend?

The reason why you wouldn’t immediately freeze in space is because there is no matter to conduct your body heat. Of course, it’s extremely cold, and even a moment in space would be a bad time. But just because the temperature is remarkably below any extreme you’ve ever experienced, it doesn’t mean you’d immediately become an ice block.

So if you won’t explode in space and you won’t die from freezing, how would space kill you? You’d probably suffocate.

But let’s assume this isn’t a man vs. nature scenario. Let’s say it’s the future, and you’re trying to defend yourself from a violent alien race.

3. Kill It With … Lasers

Two inaccuracies persist regarding lasers. Think of any energy weapon in sci-fi, and what visual comes to mind? It’s probably a dash of red light flying through the air, right? Well, if it’s a laser, there are two things wrong with that picture.

First, lasers move at the speed of light, so they hit their targets instantaneously. Also, as a result, they won’t emit a small dash of energy like a projectile. They will draw an unbroken stream of energy between the weapon and the target.

The second myth regarding lasers, however, is one of the most persistent in one of the most popular sci-fi franchises in history: Star Trek. You see, lasers depend on the presence of atmosphere to be visible. In space, there is no atmosphere. There is no dust to scatter the light, so the human eye would not be able to perceive it. As a result, lasers are invisible.

If that revelation just blew your mind, try to contain it because…

4. In Space, No One Can Hear You BOOM

Or rather, there’s no fire. Explosions in space are dramatically different than in atmosphere with gravity. Several factors alter their behavior, and they are not always accurately portrayed in science fiction.

First, fire depends on oxygen to burn, so anyone who tells you, “there’s no fire in space,” isn’t technically wrong, but fire necessitates oxygen. Since oxygen is in limited supply in space, it isn’t going to last very long.

Second, the exertion of force is dramatically different than on Earth. Since there is nothing to push back on the explosion, debris would fly away from the center of the explosion without a decaying rate of speed.

Finally, the sound of an explosion in space will not be deafening because you can’t hear it. Without atmosphere, sound waves can’t travel.

But while sound waves require atmosphere to carry them, objects in motion are just fine. The problem arises when they need to stop.

5. Slow Down! This Is A Neighborhood!

While there isn’t much that is less subtle than something going BOOM, there’s a subtlety related to a type of ignition that relates to propulsion. Often in science fiction, we see the spaceship approaching a planet, and we see its thrusters still burning. In some cases, we even see the spacecraft speed up. In reality, while much less dramatic, a space ship will need to fire thrusters to slow itself down as it approaches a planet. If not, depending on the approach vector, the ship’s motion could either be amplified by the planet’s gravity and pull it in for an inevitable crash, or the ship could skip over the planet’s orbit and miss it entirely.

On a related note is the misconception of “space friction” in that there really isn’t any. Newton’s Laws state objects in motion tend to stay in motion unless an outside force acts upon it. Rather, if an object is in motion, something has to slow it down. In atmosphere, we have friction to slow us down. In space, we don’t, so while in a lot of science fiction, there’s a concern about having enough fuel to reach a destination, in reality, reaching a destination is only a matter of achieving your desired velocity and then coasting. The real consideration is stopping when you get there, because if you can’t provide the force to counteract your trajectory, whatever body you’re hoping to land on will surely stop you, but your vessel probably isn’t built to sustain the impact.

9 Comments on [GUEST POST] Timothy Johnson on Five Needlessly Inaccurate Sci-Fi Myths and Their Awesome Truths

  1. James Campbell // December 19, 2014 at 8:48 am //

    Loved this article! A fun read.

  2. This is cool. Thanks for sharing.

  3. You do know that Star Trek uses PHASERS and not LASERS, right?

  4. James Munroe // January 6, 2015 at 8:17 pm //

    Re: #1 – in fact, your blood does not boil (though saliva on the surface of your tongue will), as a NASA report confirmed ( – your skin maintains your blood pressure sufficiently to prevent this.

  5. Harry Blanchard // January 6, 2015 at 8:41 pm //

    Remember too, it’s not just Newton who gets ignored, but Einstein as well…

  6. “First, lasers move at the speed of light, so they hit their targets instantaneously. ”

    Ummm, no. The speed of light is 299,792,458 meters per second (in a vacuum,) which sounds like an awful lot. In a space battle, however, distances would likely be thousands, if not hundreds of thousands of kilometers. That said, a laser beam travelling from Point A to Point B would take an appreciable amount of time — much as a radio signal takes about one second to travel from the Earth to the Moon.

    Sorry, but that’s not “instantaneous.” And keep in mind that space is awfully big. The likelihood of two sparring spacecraft exchanging broadside blows like two 18th century sailing ships is slim to none.

  7. Jon Humphries // January 7, 2015 at 9:29 am //

    Great article. Whilst you’re right about fuel, in sci-fi we’re generally looking at interstellar travel. Arguably a certain amount of fuel is needed to accelerate to the extremely fast speeds that these ships would need to attain to reach the target destination before they ran out of water, food, oxygen or died of old age. Also I’d say a very decent chunk of sci-fi ships travel by FTL (Faster Than Light) which tends to need exactly one unit of “SuperFuel” to work.

  8. Harry Blanchard // January 7, 2015 at 11:13 am //

    In the movie 2001, Bowman makes a short trip through vacuum in order to re-enter Discovery. I recall at the time there were critiques that this was impossible. However, according to Jerome Agel (“The Making of Kubrick’s 2001”) Clarke (who had a degree in Physics) proclaimed that it was in fact plausible. Despite getting this right in the 60s (well, maybe), many subsequent sf movies (e.g. Outland) proceeded to have people blowing up in vacuum as if they had eaten too much pizza, as in Myth #1. Sturgeon’s Law yet again, perhaps.

  9. John Smith // January 7, 2015 at 1:31 pm //

    If battles happen as portrayed in Sci-Fi, I wonder if you might just hear some explosions – not because the sound travels in space, but because your ship might be fitted with speakers to create them. The advantage being sound tells you what and where something is happening even when you aren’t looking at it so could be very useful way of conveying information.

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