MadSci Network: Agricultural Sciences
Query:

Re: how do we know aliens didn't make crop circles?

Date: Mon Feb 7 22:53:49 2005
Posted By: Neil Saunders, Research fellow
Area of science: Agricultural Sciences
ID: 1106615038.Ag
Message:

Hi Arun,

Thanks for your very interesting question. You are in good company - I don't believe that aliens make crop circles either, nor do any of the scientists that I know, or indeed most of the non-scientists. So perhaps I can ask your question slightly differently - why don't scientists believe that aliens make crop circles? To answer this, we need to look at how scientists try to solve problems and answer questions.

Let's imagine that you are walking through a field, when you come across a crop circle. "That's interesting", you say to yourself, "I wonder how that got there?" This is the first step in asking a scientific question - you make an observation (the circle), you think it's interesting and you decide that you want to explain what you are seeing.

So, you come up with some possible explanations. In science language, this is called "forming a hypothesis". Perhaps the circle formed through a natural process - maybe the wind, perhaps a whirlwind or tornado, or some electrical discharge like in a thunderstorm? Or perhaps it was made by people, who tied a length of rope to a post and walked round and round to flatten the crops? Or just maybe, something circular and heavy was resting in the field? Could that be an alien spaceship?

Now you want to gather evidence for and against all of your alternative hypotheses. You might do further observations. For instance, you could set up video cameras to watch the field and see if the circles appear again and that way, you might film what makes them. If you worked in a laboratory, you might be able to build a small model of a field and test the effects of electricity or wind on it. You would also read as much as you could to find out if other people had seen this before and to see if they had done experiments or come up with explanations. Gradually, you would start to see that some explanations had more evidence in their favour than others and those explanations were more likely. At this point, your hypothesis becomes a theory. In everyday language, you might hear people say "it's just a theory", but in science, a theory is a very good explanation of an observation with lots of evidence to support it. (By the way, this is the definition that you should give to anyone who says that evolution is "just a theory").

So scientists have done all of these things when they have looked at crop circles and their best theory is that they are made by people, who sneak into the field at night when no-one is around and make the shapes for fun. When you think about it, that's also the most likely explanation. If your hypothesis is that crop circles are made by aliens, you have to assume an awful lot of things. First, you assume that there are other intelligent life forms in the universe. Then, you assume that they have figured out a way to travel enormous distances through space and that for some reason, out of all the places in the vast universe, they have come to earth. Next, you have to explain why they have not been detected - yes, some people do claim to have seen them, but there is no strong scientific evidence at all. Finally, and most strangely, you have to wonder why they would bother to come all that way just to land in a field in the middle of the night, make some circles and then go away again. You can see that with the alien explanation, we are assuming all kinds of things for which there is no evidence. So as well as the scientific data, we are making use of a principle called "Occam's razor", which says that a hypothesis which makes fewer unfounded assumptions is more likely to be correct than one with more assumptions.

Scientists are not narrow minded people - they just expect that if you make a claim about how something works, you can back it up with good evidence and a strong theory. So to answer your last sentence - "how do I know they didn't?" - you can say, at least I know why I believe they didn't. The people who believe that they did can't tell you why they believe what they believe and that makes you a better thinker!

Keep being critical!
Neil


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