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
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)
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 www.setiathome.com Also,
the movie Contact, with Jody Foster and Matthew McConaughy is quite
philisophical about this topic.
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".
University of Wyoming
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Update: June 2012