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Name: Carla
Status: other
Grade: other
Location: NV
Country: N/A
Date: N/A

My question is regarding extraterrestrial life. I was reading an article on the NASA webpage that said SETI was looking for radio and/or television signals assuming that if there was intelligent life it might possibly be in possession of this technological knowledge. My question is, why would scientists believe that if other intelligent beings existed, they would even need to invent radio and/or television for communication? The lifeform would have had to develop eyes and ears in that case. Wouldn't it be kind of a long shot that another lifeform from another section of the universe would have arbitrarily developed along the same physical lines that humans have? Taking into consideration the laws of probability and how circuitously we got to where we are right now on the evolutionary tree of life through random mutation, what are the chances of another lifeform developing in even a remotely similar way so as to mimic us?


While I agree with you that it would be fortuitous that an intelligent life would also be in possession of something like television and radio, the extraterrestrial life forms need not have developed in quite the same way that we did. Remember that radiowaves are invisible to our natural senses and yet we use it to broadcast and detect signals. While lifeforms may differ in their evolution, the physics in any world should still be the same.

Ultimately, however, I think we should also look at it from the perspective of what signal might *we* be able to detect. Because of the distances of space, trying to detect a light-based signal is the only one that makes sense. Light is the only thing we can detect (so far) that can travel the distances of space within any meaningful time and with low interference. Light can also carry a message. It sounds like we are looking in places where there is better, uhm, light, but, really, it's our only (current) choice.


While the physical look of humans might not be replicated exactly as we on Earth are, the probability of intelligent life having very similar traits to humans is pretty high. To understand this, one must understand what traits intelligent life forms have in the first place. One of the biggest advantages is that our senses are focused right around our brain. Sight, hearing, taste, smell and touch are all very acute on our heads, which are all very close our larger than average brains. It is this concentration of senses in one place that has helped us evolve through time into "the top of the food chain".

Also, in order for life to form in the first place, a planet with very similar properties to Earth is fundamental in allowing life to begin in the first place. So already the environment for any life to begin is a narrowed set of conditions. It would make sense that any life form that has senses concentrated around a bigger than average brain would evolve to the top of the food chain once life is created and begins evolving. Since the fundamental properties of physics and math should hold true anywhere in the universe, if this alien race became so intelligent that it could develop math and physics, then they are bound to do it in similar fashion to how we humans have discovered these things.

The signals that we are looking for are repeating patterns of signals that we know could actually make the trip through space from distant stars to Earth in the first place. We are no looking for short range signals, so that narrows the bandwith or window of signals that we have to search for in the first place. We also assume that if they develop technology akin to ours, that they would come to the same or similar conclusions as us and send and look for patterns.

There are plenty of websites out there that will explain this further. I first suggest visiting the seti@home website at Also, the movie Contact, with Jody Foster and Matthew McConaughy is quite philisophical about this topic.

Matt Voss

It might not be very likely that ET will look much like us, even to the extent that ET from the movie or the stereotypical big-headed vertical-eyed Roswell aliens look like us. However, chances are good that they will have some way to detect light and sound, because those are such good mechanisms to learn about one's environment. Even on Earth, the eye evolved independently about forty times, I think.

It also makes fairly good sense that advanced civilizations will figure out how to communicate using radio or other electromagnetic waves. They're fast. And more to the point, if "others" don't use EM communication, how can we Earthbound humans possible learn about them? So we can only look for what we have "eyes" to "see".

Richard Barrans
University of Wyoming

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