Aliens - where are they?

[Magic_Man]

Back in undergrad I took a class called "History of Ancient Astronomies." It was a little mistitled, because it was mostly a cosmology class. We talked about the cosmological views of various cultures, particularly the Mayans & Aztecs, but we talked about our own personal cosmologies as well. There was a bit of relativity and astrophysics thrown into the mix. A cool class, at any rate.

Anyway, one of the discussions we had was on the existence of aliens. Most people in the class believed that there was intelligent life out there, somewhere, so where are they? Earth, I believe, is a fairly young planet, so presumably there could be life out there that has been around FAR longer than us, and could have developed interstellar travel. Why have we never received convincing communication or visits from extraterrestrials? A number of theories were offered:

1) They simply haven't found us yet. The universe is large, but life is rare, and we're just too far away and tough to find.

2) Perhaps interestellar travel over any appreciable distance is too hard, so unless they're nearby, they'll probably NEVER come here. Of course, this doesn't explain why we don't receive messages.

3) They ARE here, and we simply aren't convinced. Those loonies in the tabloids are actually right.

4) They are so advanced that they are monitoring us and purposefully avoiding contact with us, for any number of reasons.

5) ...

I could probably come up with more, but I'm interested in your ideas. I tend to choose number (1) when pressed. What do you think? Are aliens out there? Will we ever contact them?

[reb]

If they have peaceful intentions maybe they think that we are too dangerous to approach and if they are hostile and know about us we should have known by now so in this case I pick number 1.

[bocablkr]

1 and 2 are probably correct.

[Justin A]

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2) Perhaps interestellar travel over any appreciable distance is too hard, so unless they're nearby, they'll probably NEVER come here. Of course, this doesn't explain why we don't receive messages.

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Yes it does. Messages can't get here faster than the speed of light.

[mjkidd]

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2) Perhaps interestellar travel over any appreciable distance is too hard, so unless they're nearby, they'll probably NEVER come here. Of course, this doesn't explain why we don't receive messages.


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Actually, them picking up any sort of radio waves we're sending out would be tough at any sort of distance. A powerful AM radio station has a power of about 100,000 watts. So, assuming a 1 km wavelength, a radio station is pumping out 5.0e32 photons/sec. Lets say someone is trying to pick up a signal from us using a radio telescope 100 light years away...the area of a sphere with a 100 light year radius is 1.1e33 square meters. So if they have a radio telescope of 100 square meters pointed right at us, they are going to recieve a stream of data consisting of 50 photons/sec. This is not a strong signal.

[pokerbobo]

There are a few things you need to examine here.

Lets assume for sake of discussion there are other intelligent life forms out there. (it is almost a mathmatical certainty that they are there based on the number of stars like our sun and the number of planets in the "life supporting" distance from those stars.)

What reasons would they come?
Really there are few answers to this. the first being that their sun is about to expire and they need a new planet. If this is the case, they would likely exodus to the nearest planet that suits their needs. this would almost always keep them in the same galaxy. The cost and resources required for a mass exodus like this would obviously be enormous. This fact leads into the second reason and makes reason number two extremely unlikely.

The second reason some people would say is to conquer us. This is very unlikely in my opinion. If another life form has the technology to travel the great distances needed to reach us, obviously they are much more tech advanced than we are. This means that this alien civilization has passed thru the "self destruction" or "nuclear" threshold. Which means they have been able to develop and harness the energy required to kill off their entire civilization and managed not to do it. (Earth has recently entered this threshold, but we are not near passing thru it) The innovation and technology required to advance to this point can only come from a freedom loving and capitalist society. There is no long term innovation in any other way of life. Once again cost and resources come into play. The cost to invade and destroy human life on earth would likely exceed any war spoils gained by coming here.

The third reason is just plain galactic contact. This would likely be on audio or video contact prior to actual physical contact, but my guess is that will not happen unless Earth passes thru the nuclear threshold. Why would you show further advanced technologies to a society that still has yet to prove it desires to exist for eternity, and may use those technologies in a desructive fashion.

i guess in summary, what reason would a further advanced people want to come here. We cannot offer them any intelligence they dont already possess, we have shown many times we will kill based on differnces among humans (ie religion and skin color) so on a galactic level we are not a very inviting planet. [img]/images/graemlins/cool.gif[/img]

[Rearden]

Either theyre not within reasonable distance (we may be a backwater and we would be infants with toy guns compared to their tech) or we're not worth bothering (Im not a Star Trek fan but I always enjoyed the concept of contacting a civilization only after it had advanced to a reasonable tech level). Coming to conquer us... that seems far fetched. If they can travel faster than light or have built a civilization that has expanded to multiple planets or systems Im sure terraforming is nothing for them, nor mining dead worlds, etc... why would they even want to bother with us?

I think another interesting topic on this is...

Aliens land tomorrow and make contact at official levels and announce peaceful intent ["We're just here to see whats up and help you guys advance and stuff"] while displaying (obviously) tech abilities and intelligence beyond our own.... society reacts how?

I say mass chaos. I dont think society can handle that shock. The collective view of billions being shattered... yeah. Paranoia... fear of the outsiders... that would live on well beyond the lifespans of anyone involved with that first meeting I think.

[Magic_Man]

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The third reason is just plain galactic contact. This would likely be on audio or video contact prior to actual physical contact, but my guess is that will not happen unless Earth passes thru the nuclear threshold. Why would you show further advanced technologies to a society that still has yet to prove it desires to exist for eternity, and may use those technologies in a desructive fashion.

i guess in summary, what reason would a further advanced people want to come here. We cannot offer them any intelligence they dont already possess, we have shown many times we will kill based on differnces among humans (ie religion and skin color) so on a galactic level we are not a very inviting planet. [img]/images/graemlins/cool.gif[/img]

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The only problem with theories like this, and other things people say like "oh they obviously don't contact us because we are so immoral and evil", is that in order to KNOW that we are not sufficiently advanced/moral, they would have had to contact or observe is in some way. I suppose a highly advanced people might have some technology that would allow this to be performed undetected, but I find it much more likely that they just don't know we're here.

[Magic_Man]

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2) Perhaps interestellar travel over any appreciable distance is too hard, so unless they're nearby, they'll probably NEVER come here. Of course, this doesn't explain why we don't receive messages.


[/ QUOTE ]

Actually, them picking up any sort of radio waves we're sending out would be tough at any sort of distance. A powerful AM radio station has a power of about 100,000 watts. So, assuming a 1 km wavelength, a radio station is pumping out 5.0e32 photons/sec. Lets say someone is trying to pick up a signal from us using a radio telescope 100 light years away...the area of a sphere with a 100 light year radius is 1.1e33 square meters. So if they have a radio telescope of 100 square meters pointed right at us, they are going to recieve a stream of data consisting of 50 photons/sec. This is not a strong signal.

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Presumably, there are lifeforms with sufficiently advanced technology to be able to detect this kind of signal, or at least to be able to send one of their own.

[George Rice]

Life as we know it requires water and other fluids to exist. This reduces the possible places that can sustain it. And such places must be able to sustain it for millions of years for all the requisite evolution to develop. And the planets must evolve too. So while Earth may be relatively young, so too may be most other planets that may have life on them.

The distance that must be traveled is too great for living beings to survive. Both because of life span and supplies needed to make the trip.

Communication is only possible if similar technologies and language structure develop. For all we know, light coming from some of the stars is being modulated some how and we have no way of deciphering it.