[tweener]

Maybe we can't find alien life because the universe is so tremendously huge that the probability of finding them is extremely small.  Think of the entomologist trying to study ants, but there are only 10 colonies in all of the land surface of the earth.  And because of the "speed of light" limitation (in the universe not the analogy), she cannot go faster than a slow walk.  Odds are the entomologist will have a very very long search.  Maybe longer than the life span of her "civilization".


----
John

[drkev]

We will never make contact with extra terrestrial life and we will never make journeys into deep space.

The simple answer follows:

E=MC squared. Where E is energy required, M is mass and C is the speed of light.

Now based upon this equation, the closer we get to the speed of light, the more energy is required. If we plot this equation on a graph, we find that when we get to the speed of light we require infinite energy and infinite mass.

Now as this is impossible we can summise that nothing can travel faster than the speed of light.

I do not know how far away the nearest inhabited planet is but I'm pretty sure that it is millions of light years away.

This means that at the speed of light it would take millions of years to get there.

Thus we can see that this would be impossible.

When I have told people this before I usually get the "Star Trek" response ie "It might be possible if we had the technology..." This isn't an issue of technology but the laws of physics.

Intergalactic travel is and always will be impossible but then I'm a Pharmacologist and not a physicist.

Live long and Love life

Kevin Fisher

[tweener]

drkev -
There are some theories being bantered around that might allow for "faster than light" travel.  I don't understand the details, but they involve tunneling through other spatial dimensions to come out in another area of our own four dimensional space.  It's probably a long way off.


----
John

[NakedScientist]

We did a piece about time travel and wormholes last year.

Here's the link. The audio is in the third block down, and the text transcript is at the bottom of the page under "full length text" - click top right.

http://www.thenakedscientists.com/html/shows/2002.05.26.htm

Chris

[Pappy]

This subject came up during dinner with some friends. I'm constantly amused at how vigorously people insist extraterrestrials are here now or have visited in the past based on a negative argument (prove they're NOT here!). I'm also amazed at the suggestion that our government is suppressing the evidence and has dead aliens, crashed space craft, etc. Wow, in this day and age of fast information, a free and vigorous press and an abundace of interested, probing individuals, no government agency is that secure and non-porous. It's funny how people are so quick to point out the stupidity and incompetance of our government, except when it comes to hiding the evidence of alien visitation. In that respect, they are flawless! In addition, is the USA the ONLY country visited, certainly not.....perhaps every country has been visited and EVERY government is successfully hiding the evidence....ABSURD!!

The reason no tangible evidence has been presented is because there is no tangible evidence to present!! Occam's Razor!

[Pmb]

Amoung many other very important factors I think that the most imporotant factor is that intelligent life is so rare that its two species living so close togther in interstellar space is next to zero. It's just too difficult to comminicate over those distances with any technologym, even ones that we haven't been exposed to at all.

[CliffordK]

If someone is trying to publish the DNA sequence of Sasquatch, we should next see a publication of the DNA of "Aliens", and alien-human hybrids, showing startling similarities to the researcher's own DNA.

The prerequisite for intelligent life is just life.  And, unfortunately we don't know how common either one is, or whether it is possible for life to be something other than hydrogen/carbon/oxygen/water based. 

"Nearby" is all relative, astronomically speaking.  There about 260,000 stars within 250 light years of Earth. 

The two-way communication delay would be quite extraordinary between systems 250 light years apart, but one could imagine sharing data streams over moderate astronomical distances, even if direct travel is not practical.

The question is whether "life" or "intelligent life" is more common than 1:260,000

[syhprum]

I sometimes wonder if the extra-terrestrials have a different conception of time to us so that instead of looking for signals in a 1 Hz bandwidth we should be looking at a 0.001 Hz bandwidth. 

[CliffordK]

The bandwidth of the signal would depend somewhat on one's ability to decode the signal.  I'm not real familiar with computer communications, but it would not be too surprising to use multiple channels for parallel communication, using as tight of frequency separation as could be discerned.  Perhaps adding a timer signal to correct for frequency shifts.  To an outsider, such parallel data transfers might look like "noise".

Our radio signals, of course, incorporate both amplitude modulation (AM) and frequency modulation (FM).

If one wished to initiate "first contact" with an alien species, say 250 light years away, I would think one would choose a very simple signal until one could ascertain that both parties were listening, then choose a more complex pattern.  Or, perhaps both transmit a simple AM signal, as much to get attention as anything else, as well as a much more complex data transfer signal.  Could you embed the key for the complex signal in the simple AM signal?

Of course, if one was just intercepting communication such as we use to voyager, and various satellites and deep space probes, then that would depend on the technology at the time of manufacture.

Anyway, a "first contact" signal should also be transmitted continuously, or as continuous as possible, just to increase the possibility that someone is listening.

[evan_au]

Dolphins live in the sea, so that makes them non-terrestrial.
Why can't we learn to communicate with them, first?

[yor_on]

You know Evan. I think we do know how to communicate with other animals here. We just don't notice that we do. And sometimes we don't want to notice it either, consider how many cultures that treat animals as less than humans, then consider how we use them for our food industries. To do the same with humans would indeed be inhuman, but seems acceptable when it comes to other species.

[Pmb]

I think spending millions of dollars on trying to contact something in space is rediculous. .

It's hardly ridiculous since it would answer a question that we've all been asking since the man walked the Earth: Are we alone?

It would make an immense difference to everyone on the planet. Hardly a ridiculous effort.

[syhprum]

I do not think SETI ridiculous but rather futile if we did find evidence of intelligent life the distance would probably be so great that with the large time delay any conversation would be impossible 

[imatfaal]

Syhprum - I agree with Pete, it would be an incredibly important moment in world history, finally knowing we are not alone.  I think it would alter the way we approach many things

[CliffordK]

If we wished to establish communication with aliens, perhaps the best thing to do would be to broadcast a "here we are" signal.

The likelihood that a single burst sent towards a neighboring star would be picked up would be low.

Earth, of course, "leaks" some radio waves, but not at a power or design to attract attention of extraterrestrials.  Perhaps communication satellite uplinks, but even those would tend to sweep around the sky on a 24 hour basis, and not give continuous coverage anywhere.

What we really would need is a powerful omnidirectional broadcast antenna sending out, a simple, but unmistakably artificial signal.  Then on a different frequency, perhaps a weaker signal carrying a digital photo dictionary, uncompressed, of course, and other selected communication.  Embed information to find the second signal in the first one.  And, if a response is received, to expect to send directed communication on a 3rd frequency.

And the signal pair would have to be continuously maintained for thousands, or perhaps millions of years, while always scanning for a response.

If we are unable to, or unwilling to invest in initiating contact, why would one think that an alien race would be doing it?