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Review: Contact
The movie was based on the novel of the same name by the famous astronomer Carl Sagan. Sagan was a brilliant researcher, and found that he was even better at describing the wonders of the Universe. He explained science to people in a way that not only could they understand, but so that it also moved them and made them appreciate the awe and majesty of the sky around them. I could write reams about the man and his influence both on the public and astronomers, but that's already been done. Let's talk about the movie instead. ``Contact'' stands out from almost every other science fiction movie ever made in that it went to great pains to be accurate. Almost all of the plotline is based on either solid physics, or extrapolated from current theories. Some of the astronomers were slightly exaggerate in character, but it's safe to say that every stereotype depicted in the movie has seen its moment in real live astronomers. I'm glad that the Ellie Arroways outnumber the David Drumlins though! Mind you, some of the characters are based at least in part on real people: there is a blind SETI astronomer named Kent Cullers (in the movie the character was named Kent Clark). Despite her denials, I think Jill Tartar was in large part the inspiration for Ellie. If Sagan had an inspiration for Drumlin, he never said who it was. Those of you familiar with my reviews know that I take a dim view of science errors in movies. However, I loved ``Contact'' and so I am willing to give it more leeway. Does that sound unfair? Too bad! It's my website! ;-) Actually, I am willing to give it more leeway because to went to such lengths to be accurate. While there are some errors in it, most are small, and some of the parts it got right are so amazing that I am astonished at the level of detail. In light of that, this review will be a bit different than the others: along with the errors, I will point out little details that were correct. The next time you watch the movie, check them out! So: on to the review!
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That said, there are some problems with it astronomically. One of the points it is making is that the farther from a source, the farther back in time it appears to be. Light waves (of which radio is a part) travel at 300,000 kilometers per second. The Sun, being about 150 million kilometers away, is about 8 minutes away at the speed of light. So, in a sense, we see it as it was 8 minutes ago. As we pull back from the Earth in that opening sequence, the radio broadcast we hear represents that by playing older and older songs and other radio bits as we get farther away from home. The problem is, the radio goes back in time too fast. We are hearing radio shows from years gone by before we ever leave the solar system. However, it only takes light about 6 hours to go from the Sun to Pluto, so really at that distance we'd hear radio from 6 hours before. Having said that, I'll add that this doesn't bug me. I'll chalk it up to artistic license. They are trying to make a point ,and had to compromise on the timing. As far as I'm concerned, that's okay. If you want to get really picky, we shouldn't hear radio at all: we're apparently moving faster than light in the sequence, and would leave radio waves behind us. If we heard them at all, they'd sound backwards!
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They do show too many asteroids though! On average, there is about 2 million kilometers between asteroids out in the belt. They are also small and relatively faint, so you could be in the middle of the thickest part of the belt and not even see a single asteroid with the naked eye! So the flurry of asteroids shown in that sequence is overestimating how many there really are.
One more note: they show the Red Spot rotating counterclockwise. I was suspicious; it's in the southern hemisphere, and hurricanes on the Earth's southern hemisphere rotate clockwise. However, the Red Spot is a high pressure system, while terrestrial hurricanes are low pressure systems. A high pressure system rotates in an opposite sense from a low pressure system. They got that right! Pretty neat.
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Good: The Eagle Nebula image is probably the most famous Hubble picture ever taken. The composition and color are beautiful, eerie and dramatic. The problem is, in the opening sequence, after we pass through it we see as if we were still seeing it from Earth. The point is, we should be seeing it from the other side, and so it should at least look flipped left-to-right. In reality, the structure has three dimensions, so it probably looks very different from the backside. Still, this was a very cool effect.
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One more note on this one: when we see Ellie listening on her headphones, in the background is the Very Large Array (VLA), a collection of 27 large radio telescopes near Socorro, New Mexico. You can see a few of them in the image above. This is a real site, and they simply filmed the scene there. However, when the scene first appeared, the guy in the seat in front of me at the theater leaned over to a friend and said ``What a great effect!''. He thought it was a computer image! How cool is it that we astronomers have instruments so impressive that people think they aren't real? ;-) Another One More Note (August 24, 2000): I get email from people asking if her walkie-talkie would interfere with the signal being received (when she first hears the Signal, she grabs her radio and starts yelling coordinates to her assistants). Bad Reader Ted Brattstrom asked Dave Finley, an astronomer at VLA, about this. Dave replied that since there are multiple dishes, interference at one is no big deal. They also have electronic techs who make sure the walkie-talkies are ```clean'', and do not interfere with the observations. Dave also told me that they allow cars as well; at some observatories, the spark plugs from cars messes up the signal as well. Only diesel cars are allowed; they have no spark plugs. Again, at VLA that's not such a big problem.
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Also, it is established later in the movie that her father died on November 10. There are no good showers on that date! The Leonids peak a week or so later, but are usually a fairly weak shower (except every 33 years). She wouldn't have been that excited about them; as a matter of fact, she sees a couple of meteors within a few seconds, which implies a pretty dense shower. As always, I am willing to forgive this because really, I am not that picky, and it's not that big a deal.
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Good: This one is subtle, but neat. Actually, the ships should heel
the other way, so that the decks lean away from the Machine. Why?
Because buoyancy works such that the deck of the ship will float horizontally
with respect to gravity. A ship in still water will have the deck perfectly
horizontal. If the gravity were to tilt, then the deck would tilt the
other way, so that it stays horizontal (what physicists call "normal")
to the direction of gravity. Like I said, subtle. So subtle I completely
missed it, and it took Bad Reader Kyle McIntire to point it out to me!
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The problem is the movie had too much dust around Vega. Measurements show that the total amount of dust is about one-half the mass of the Moon. That ain't much! Imagine it spread out over trillions of cubic kilometers of space... you could be in the middle of it and never notice. To be fair, that mass would be in the form of dust, and there might be bigger particles that we haven't detected. But that wouldn't add up to much. I remember an undergrad class I had shortly after the dust cloud was discovered. We were told how much extra IR light was coming from Vega, and we had to calculate the mass of the dust! My poor primitive computer could barely work out the number, but I was shocked to find out it was less than the mass of the Moon. My vision of planets circling a nearby star were dashed. I had to wait 15 years before the first real extrasolar planet was discovered. Another note: it wasn't as clear as it could be in the movie, but the aliens were not from Vega. They had an automatic radio telescope of sorts orbiting the star, listening to nearby stars. That's how they detected us. We don't know from where the aliens themselves came, but I'll note that just before Ellie is whisked away from Vega by the wormhole, some sort of array can be seen in the corner of the screen. I thought that was a very nice touch. She actually glimpsed the telescope that detected Earth in the first place!
[NOTE (May 11, 2000): This next Bad/Good section deals with Ellie's trip taking no time to the outside world. I originally argued that this was not possible. I was wrong; at least, I was wrong in the context of the movie. Sagan established both in the book and in the movie that the aliens have faster-than-light travel, and even may have the limited ability to travel in time. Basically, they took Ellie out of her coordinates in space and time, chatted with her for a while, then put her back to her original coordinates in space and time. Therefore, no time elapsed for people back on Earth. I have received copious emails about this pointing out my error! I have left it in so you can read it anyway.]
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The only way around that is to assume that the aliens could somehow
manipulate time, and I have to draw the line there. Her ``father'' admitted
they did not build the transit system, so I have severe doubts they
could shape time the way they want. It's a neat plot twist, but
the zero-time trip won't work.
Conclusion:
If you liked the movie, or even if you didn't, you really should read the book. It's a lot better than the movie, and has many concepts only hinted at in the movie. I have read it several times, and the hair on the back of my neck stands up every time I read the second to last chapter... If you want to buy it, you can order it from amazon.com through my website, or go to a used bookstore and pick up a copy. I think you won't regret it.
There are a lot of links for the movie, and for SETI on the web.
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