How Sci-fi Doesn't Work

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Black Holes in Sci-Fi

A supermassive black hole ripping apart a star and consuming a portion of it.
A supermassive black hole ripping apart a star and consuming a portion of it.
Image courtesy NASA/CXC/M.Weiss

In contrast to weightlessness, some sci-fi films tackle an object where gravity is extremely high: a black hole. Near the end of "Galaxy Quest," helmsman Tommy Laredo tells Capt. Jason Nesmith that the NSEA Protector must go through a black hole to return to Earth. In Disney's "The Black Hole," a spaceship crew goes through a black hole and ends up in another place far away. The problem is that you cannot go through a black hole.

A black hole is caused by the collapse of a star at the end of its life (The star must be at least three times more massive than the Sun). The core of the collapsed star becomes so dense and the gravitational forces so great that nothing, not even light, can escape. A black hole is not a tunnel. Any object that enters the edge or event horizon of the black hole falls into it. The gravitational forces inside would rip any matter apart.

One misconception about black holes is that they suck everything nearby into them like a huge vacuum cleaner. This is not necessarily true; only objects that fall within the event horizon go into the black hole. They will attract objects by virtue of their mass and gravity just as the star that bore them did (remember that the black hole has the same mass as the star, just more compact, or dense). If the Sun were to instantly become a black hole, many people think that it would suck the Earth into it (Although the Sun does not have enough mass to become a black hole). But if you examine Newton's law of gravity above, neither the mass of the Sun nor the Earth changes, and neither does the distance between them. So, the Earth would experience the same gravitational attraction to the Sun if it became a black hole as it does now. The Earth would merely orbit the black hole, just as it orbits the Sun now (The loss of sunlight would cause severe problems for life on Earth, however).

Next, we'll look at how science fiction has handled lasers, sound and aliens.