Alien Opinions

[mxsoar]

Hi everyone,

i am currently engaged in a school assignment in which we have to produce a 25 minute radio show to be broadcast on New Zealand radio later this year.
My friends and I are doing an investigation on extraterrestrial theories and concepts.
It would be really helpful if some of you could post your opinions on the subject of aliens and there existence.
By posting in this topic you agree that whatever you write may be broadcast our local radio station later this year.
thanks

[vbloke]

I recently taught my class about the possibility of alien intelligence (which is different to the possibility of alien life). This featured the Drake Equation, which is
N = R* x fp x ne x fl x fi x fc x L
where
N is the number of civilizations in our galaxy, with which we might hope to be able to communicate;
and
R* is the rate of star formation in our galaxy.
fp is the fraction of those stars that have planets.
ne is the average number of planets that can potentially support life per star that has planets.
fl is the fraction of the above that actually go on to develop life at some point.
fi is the fraction of the above that actually go on to develop intelligent life.
fc is the fraction of civilizations that develop a technology that releases detectable signs of their existence into space.
L is the length of time such civilizations release detectable signals into space.

So, this gives us
N = 6 × 0.5 × 2 × 0.33 × 1×10-7 × 0.01 × 69 = 1.3 ×10-7 = 0.0000001

This is not a measure of the possibility of any type of life, just intelligent life.

Other assumptions give values of N that are (much) less than 1, but some observers believe this is still compatible with observations due to the anthropic principle: no matter how low the probability that any given galaxy will have intelligent life in it, the universe must have at least one intelligent species by definition otherwise the question would not arise.

Also, given that complex carbohydrates and amino acids have been discovered spectroscopically inside Giant Molecular Clouds and various nebulae (from which stars and planets are made), then the building blocks of organic chemistry already exist in the universe, ready to be deposited on planets which might well give rise to simple forms of life, such as bacteria and microbes.

In order (according to current theories) for life to arise, you would need a stable star (no blue giants, red giants or other variable or short lived stars), the planet needs to be inside the "goldilocks zone" (the place where liquid water can exist) and should be of sufficient age that life can arise.

Recently, Gliese 581 c, a possible terrestrial planet has been found around a stable red dwarf star (Gliese 581) at an orbit where liquid water could exist, so it is a possible candidate for life.

[mxsoar]

Brilliant! thank you very much for that post it's exactly what we're looking for!
But do you believe in the existence of intelligent life and that we may have made contact on earth or do you just believe in the possibility that there is intelligent life out there?

[vbloke]

It's a question that has taxed the minds of mankind for time immemorial.

I do believe that there is intelligent life out there, however, I very much doubt, given the sheer size and scale of the universe, that it's likely that we'll ever be able to meaningfully communicate with it.

It takes light 300,000 years to cross from one end of our galaxy to the other and our nearest "neighbour", Andromeda is 2.5 million light years away - light (and any signal) takes 2.5 million years to reach us.

Even assuming a relatively nearby intelligence, it would take vast resources and power, as interstellar dust absorbs energy - the clarity of a signal degrades over distance. Even then, let's assume intelligent life on Gliese 581 c, it would take 20 years for a signal from them to reach us and another 20 years to get one back (assuming that there was no problem in actually understanding and translating the message).

The closest we have ever come to potentially discovering something was in 1977 - now known as the Wow! signal. It was a strong narrowband radio signal detected by Dr. Jerry Ehman on August 15, 1977 while working on a SETI project at the Big Ear radio telescope of Ohio University. The signal bore expected definitions of a potential non-terrestrial and non-solar system origin. It lasted for 72 seconds but has not been detected again.

Amazed at how nearly the signal matched the expected signature of an interstellar signal in the antenna used, Ehman circled the signal on the computer printout and wrote the comment "Wow!" on its side. This comment became the name of the signal.

[Cuddles]

In my opinion the Drake equation is worse than useless. It gives the impression there is actually something scientidic when it is just pure guessing.

R* = Rate of star formation. A bit is known about this, but certainly not enough to put a single solid number on, especially since the rate varies so much in different places and at different times.

fp = Fraction of stars with planets. Again, a little bit is known, but nowhere near enough to put a number on. At present we have found very few extrasolar planets, and just about every time we do we discover something new about how and where planets form, so this number is constantly changing.

Every other term is simply made up. We do not know which planets can support life, we don't know how common life is, and we certainly don't know anything about intelligence or how any technology other than ours might progress. We don't even know how our own technology will progress. For example, estimates for planets that currently support life, or are capable of supporting life are anywhere between one and four or five just for our solar system. How can we possibly say anything about others when we have no idea about our own?

The Drake equation could be useful as a way of pointing out all the things we need to find out in order to guess how many intelligent civilisations there are, but to actually try to put numbers in it is utterly meaningless and extremely misleading.

[vbloke]

I wouldn't worse than useless, but I would say it's not accurate as most of the variables are unknowns, but it's a useful gauge for academics of astrobiology.

[wollery]

Sorry vbloke, but Cuddles is right.

Also, the Drake equation gives a measure of the number of advanced intelligent civilizations that exist at the same time (or at least, that we might possibly detect) in the Galaxy.

The Drake equation contains one poorly constrained variable, one almost completely unknown variable, and 5 totally unknown variables. It's an interesting exercise in setting out a problem, and a useful roadmap for setting out what we need to understand in order to calculate this probability, but it's little more than that.