When Science Goes Right... For the Most Part Anyway

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Stargate SG-1 is a science fiction television show.  In the show, the US military acquires a device that allows them to connect to other planets via wormholes.

In the episode "A Matter of Time," one of the military groups begins to explore a planet before they realize that it is being drawn into a black hole.  When the earth facility attempts to get in contact with the the group on the foreign planet, the gravitational effects of the black hole are transfered through the wormhole.  This causes the facility on earth to experience time dilation.

For a more complete synopsis go here.  And to watch the episode go here.

There are a few things in this episode that are correct but I will be focusing on time dilation, since this is a major point of the episode.

Time Dilation

Time dilation is when time slows down in the presence a great gravitational force, or A LOT of gravity, to an outside observer.  Let's consider a person, call him A, and another person, call him B.  And let them be separated by a great distance.  And let them each have a similar clock that are in sync.

As they are now, A and B will observe time to pass the same.  Meaning that A sees his time pass exactly like B and B observes A's time to pass exactly like his own.  So, three hours later looks like:

Now let's add a little black hole next to A, so that A is effected by the gravitational force.  And let's assume that B is far enough away that the black hole doesn't affect him. (The black hole is the dot next to A)

Now, let's view things from B's eyes.  B will see his time run normally, but see A going in slow motion.  So, when 6 hours have passed for B, only an hour has passed for A.

However, if we now view things from A's eyes, we see that time seems to be running at the same rate before.  A doesn't notice any of the time effects from his view point, on his own clock, but he'll see that B's time is quicker than his own.

The episode clearly shows this on numerous occasions.  For example, a worker is running some checks in front of the wormhole.  The personnel watching him from an observation deck view him walking and moving slowly, even his speech has slowed down.  This can be seen 21.45 minutes into the episode.

Other Right Things

Some other correct things are:  gravitational redshift, orbiting around a black hole, and tidal effects.

Gravitational redshift is when light waves are stretched.  The colors we associate with light waves is due to the wavelength, or how long the waves are.  When light gets near a black hole, the waves get stretched.  Let's look at the visible spectrum:  red, orange, yellow, green, blue, indigo, and violet.  So, if we redshift something that is violet it will now look green, and if we red shift green it will now look red.

A common misconception about black holes is that they "suck" in stuff.  Consider this.  If we were to instantaneously swap out the sun for a black hole with the same mass (you can think of mass as your weight) the planets wouldn't be "sucked" into the sun, they would continue to orbit around the black hole.  This is shown in the episode, see right, as swirly stuff around the black hole.

Tidal effect can be thought of one part of an object is feeling a stronger pull than another part of the object.  Remember A from earlier?  Tidal effects are how he will die, since he came to close to the black hole.  To the left, we see A falling head first into the black hole.  His head is stretched out, while his legs are not.  I can't even imagine how that would feel, O_o.  In the episode, the astrophysicist on the show, the blond lady, mentions how they will be pulled apart by tidal effects.

What is your favorite representation of a black hole in a movie/show/what-have-you?  It doesn't matter if it's a good or bad representation.