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Dr. Christopher S. Baird

Which space movie has the most accurate physics?

Category: Space      Published: February 23, 2013

In order to objectively answer this question, let's list the most common physics principles that movies get wrong and then judge the movies one principle at a time. Because the principles of physics apply universally to all galaxies, the excuse of "advanced technology" cannot be used to explain away physics errors in a movie. For this reason, the argument that "my favorite movie may have got the science right after all because maybe the physics is different in another galaxy" is not valid. Biology and chemistry may be different on distant worlds, but physics is not. This article contains items that are only physically impossible, and not items that may be technologically difficult. An alien race may indeed have advanced technology that we can not even dream of. But they still can't break the laws of physics. The following principles are considered:

1. No Sound in Space
There is virtually no air in space. Since sound is just vibrations of air, sound cannot travel through the vacuum of space. An exploding space ship would be perfectly silent to an external observer. (Read More)

2. Laser Beams are Invisible
To see light, it must enter our eyes. This happens when light reflects off an object or when the light source is pointed right in your eye. There are virtually no objects in space, so a laser beam shooting through space would be completely invisible. (Read More)

3. Ships Can't Travel Faster than Light
Nothing can travel faster than light, no matter how advanced its technology. This means that voyages to other planets in our solar system take from months to years and voyages to other stars take from decades to centuries. (Read More)

4. Acceleration Creates Inertial Forces
When a space ship speeds up, the passengers are thrown back violently because of the inertial forces. There is no way to cancel out or block inertial forces as they are caused by the motion of the objects themselves. Similarly, every time a space ship slows down, the passengers lurch forwards. (Read More)

5. Artificial Gravity Requires Spinning
Artificial gravity requires that all objects in a space ship feel an equal force down towards the floor. The only property that all physical objects share is mass, so the artificial gravity would have to act on an object's mass. The only effects that involve mass are gravity and inertia. Since gravity is ruled out (if there's real gravity doing the job, why would you need artificial gravity?), the only option left is inertial force. Inertial forces are created when a frame of reference spins or accelerates linearly. (Read More)

6. No Banking Turns in Space
A banking turn requires a cushion of air to bounce off of. Seeing as there is virtually no air in space, banking turns such as seen in dogfights are not possible. Space ships must turn be reorienting themselves to the desired direction and then firing their engines. (Read More)

7. No Time Travel to the Past
Time travel to the past is ruled out by mainstream physics. Time travel to the past would destroy the universe in a fireball of runaway energy. Time travel to the future happens all the time. (Read More)

8. Humans in Vacuum Don't Explode
Human tissue is strong enough to withstand the pressure imbalance between internal pressure and the vacuum of space. (Read More)

9. Space Weapons Have Unlimited Range
Because there is virtually no friction in space, no ground to hit, and almost no objects to get in the way, bullets, missiles, rockets, bombs, and laser beams travel forever in space. (Read More)

10. Asteroid Fields are not Thick
Real asteroid fields have such immense space between each asteroid that a space ship traveling through would miss them all unless it carefully aimed at one. (Read More)

11. Black Holes and Stars Don't Suck
The gravity of black holes and stars is the same kind of gravity we experience on the earth. An object near a black hole would do the same thing our moon does because it is near the earth: it would orbit the black hole and not be sucked in. For a space ship to fall into a distant black hole or star, it would have to be very carefully aimed, otherwise it would end up in orbit or slingshotting away. (Read More)

12. Space is Not Cold
Within the inner solar system, space is quite hot because of the sun. In deep space, things can become cold but it will take a long time because the vacuum of space is a good insulator. Astronauts exposed to space do not suddenly freeze. (Read More)

13. No Ambient Illumination
The ambient illumination on earth is provided by the sky. Space has no sky and therefore objects are lit only by the stark illumination of direct sunlight. (Read More)

14. Ships With Engines Off Don't Stop
Vehicles on earth experience friction from the road, the water, and the air which slows them down. Space has virtually no air, water, or ground and therefore has essentially no friction. Ships with their engines off coast forever instead of slowing to a stop. (Read More)

15. Stars Don't Move
When traveling in a vehicle, objects out the window seem to move past you due to parallax. The stars are so far away that their movement is essentially zero. Looking out the window of a speeding space ship, it appears as if you are not moving at all. (Read More)

With all of these physical principles appropriately explained, let's look at the scores. An "x" in the table below means that the movie got the physics wrong, while a check mark indicates that the movie either got the physics right or did not have any scenes where the corresponding physics would be evident.

table of space movie scores

To answer the original question, the space movies with the most accurate physics are Contact, 2001: A Space Odyssey, and Apollo 13. The movies with the least accurate physics are the Star Wars and Star Trek series. The bottom line is that if you want senseless fun, watch Star Trek or Star Wars. If you want serious space drama, watch Apollo 13 or 2001. This should not be surprising as Star Wars and Star Trek are essentially escapist fantasy while Apollo 13 depicts a true story.

Postscript: Below are principles that were not included in this evaluation because they may not be true in another galaxy, or are even not true in our galaxy.

Laser Beams Can't Kill
Despite the fact that most practical lasers encountered in every day life are too weak to hurt people, there are in fact lasers strong enough to do damage. The reason that police officers are not running around with laser guns is that under our current technology it takes a large machine with a significant energy source to create laser beams strong enough to be deadly. This roadblock is primarily technological. Lethal hand-held laser guns could become a possibility in the near future.

Aliens Don't Exist
Although there is no current evidence one way or the other, mainstream science predicts that life is quite common in our galaxy and through-out the universe. This prediction does not guarantee that alien life will be intelligent or resemble humans. Movies and television shows that are trying to be scientifically accurate are free to envision just about any shape of alien they wish without distorting science as long as basic principles such as conservation of energy are followed (i.e. creatures that expend energy moving about must consume energy in some way).

No Aliens are Humanoid
If the variety of species on earth is any indication, there is a low probability that life on alien planets will look human. But there is nothing physical that makes humanoid aliens impossible. It's just improbable that a given star system will have humanoid aliens. But multiply this low probability by the astronomical number of stars in our galaxy and humanoid aliens could end up quite common.

Other Planets are not Earth-like
While the planets in our solar system alone show that earth-like planets are rare, there is no principle that completely rules out earth-like planets. The heroes of shows may just be getting lucky in bumping into the ones that are earth-like, or avoiding the ones without breathable air. The scenario is improbable, but not impossible. Improbable things happen all the time in real life. The improbability of an event is what makes a story so interesting. The universe is so vast that improbable things quickly become probable.

Aliens Can't Speak English
The native Americans didn't speak English when the Europeans first discovered them, so it's even less likely that aliens can speak English. While this is perhaps true, this reasoning is more of a sociological argument than a physics argument. As such, we can always find holes in the argument. For instance, perhaps aliens observed earth's television broadcasts from afar and learned our language from them. Or perhaps, some English explorer had already visited the aliens and taught them English. Returning to our analogy, although the native Americans did not speak English natively, they picked it up very quickly from the early explorers. For instance, when the Pilgrims of Plymouth first met Squanto, he had already learned English. If aliens are intelligent enough to speak at all, they should have no problem quickly learning English.

Topics: movie physics, rate movies, space movie