WHAT IS LIFE ?

[afrologics]

apart nfrom our primary difenition of life i.e our definition with respect to planet earth, do you think that life could exist elwere in our own galaxy?

[Freethinker]

Define "Life" for us afrologics.

[TeleMad]

Could life EXIST elsewhere in our galaxy? I'm pretty sure it could. The question is, could life ARISE elseewhere in our galaxy?

It is often times pointed out that bacteria have been found to flourish in all kinds of extreme environments here on Earth, from extremely salty, to extremely radioactive, to extremely acidic, to extremely hot, and so on. But just because bacteria could evolve and ADAPT to such environments does not mean that life could ORIGINATE is such environments. For example, it is thought that life originated just once on Earth - all life is descended from one origin. Well, since life can EXIST in millions of different environments, why didn't it ORIGINATE millions of different times? It may very well be that the conditions required for life to arise are an extremely small subset of possible conditions, and experimentation to date supports this notion.

[Uncle Martin]

I think we have too little data to even speculate. We have one living planet to extrapolate from. The Drake equation is rather comforting but really nothing more than dart board mathematics. Then we have to consider the Fermi paradox. Which only tells me that interstellar travel is impractical, or intelligent life is rare or we are unique.

We are learning that planetary systems could be the rule rather than the exception. Nothing we observe prohibits life elsewhere, but unless SETI produces positive results we are a very long way from knowing anything definitively. If we cannot find simple life in our solar system we may never know.

[Freethinker]

I highly recomend

Probability 1: Why There Must Be Intelligent
Life in the Universe, Amir D. Aczel

It takes the Drake equation and works out in a fairly well reasonsed and supportable fasion how he comes to this conclusion.

[Uncle Martin]

I ordered that book from Amazon.com. I'm looking forward to reading it. Thanks for the recommendation. Few books I've read on the subject were more than science fiction disguising themselves as science. Intelligent extraterrestial life would be to science what the rapture would be to religion. Of course its's fun to imagine. I just hope they both occur at the same time, they couldn't handle the truth.

[TeleMad]

Unfortunately, what the book is going to boil down to, is "There MUST be other intelligent life somewhere in our Universe IF THE UNSUPPORTED ASSUMPTIONS I MAKE TURN OUT TO BE TRUE". Read the book if you want and enjoy it like any other good fiction novel.

[Bo]

i firmly believe that we leave on a normal planet, orbitting a normal star, in a normal galaxy; so there is no reason whatsoever to assume that we, or life on earth an sich (to use the beautifull german language ) are in any sense special. Bo

[Freethinker]

Originally posted by: TeleMad
Unfortunately, what the book is going to boil down to, is "There MUST be other intelligent life somewhere in our Universe IF THE UNSUPPORTED ASSUMPTIONS I MAKE TURN OUT TO BE TRUE". Read the book if you want and enjoy it like any other good fiction novel.

Funny, that's not what the book's jacket indicated! :-)

On Amazon there is mixed reviews.

SO I did a little Googleing. The biggest challenge was finding sites that were not either generic Book Reviews or "personal opinions" from those not in a position to make critical scientific analysis, e.g. he draws a lot of ire from Christian sites because he supports the idea that their god would create someone else besides them. This also means ignoring sites such as Uri Geller's or UFOers. WHile plain book review sites had good things to say because they wanted to sell you the book.

I tried to stick with sites that either were from educational institutions (.edu's) or sites that had some related scientific orientation, such as the SETI League. I found many sites that listed the book favorably as a resource on the SCIENTIFIC or STATISTICAL exploration of possible ETI. But most just listed the book and perhaps had a sentice or two, but not anything addressing specific accuracies.

These three filled the bill. Education/ Science orientation with some details RE accuracy of the presentation. Unlike at the Amazon site, I did not find a single site which met these criteria which warned against the book's (lack of?) accuracy. The only consistant possibly negative comment was that the book is more of a surface level understanding. It is not a detailed scientific manual.


SETI Book Review: Probability 1
The SETI League, Inc.

"For me, the book became more interesting as Aczel introduced mathematics (don't worry-the concepts don't transcend high-school algebra and probability), and the combination of science and a statistical framework to find solutions to problems that were thought to contain no answer. The focus of this book, and what makes it different from all of the others, once again, is the attempt Aczel makes at mathematically proving extraterrestrial existence-and the kind of existence SETI is looking for. Think of the book as a eulogy to Carl Sagan, who himself wished to write an analogous book, but unfortunately never got around to writing it. Aczel is no Sagan, but then again, who really is?"
http://www.setileague.org/reviews/probabil.htm



SEDS
S P A C E V I E W S
Book Review
"While much of the background material will be old hat for those already familiar with the field, and is not otherwise distinctive, his conclusions are novel but are firmly rooted in his analysis. For anyone looking for new evidence that we are almost certainly not alone in the universe, "Probability 1" will be an excellent read." (Students for the Exploration and Development of Space was founded in 1980 at MIT and Princeton)
http://www.seds.org/pub/info/newsletters/spaceviews/text/990108.txt



MathK-PHD
Our purpose: To bring you readable books on unreadable subjects.
Our criteria for book selection:
(1.) The book must be factually correct.
(2.) It must be readable (i.e. understandable) for non-mathematicians as well as serious mathematicians within the age and knowledge limits listed.

[i]"Aczel tackles that paradox after he goes through the statistical calculations for the probability of intelligent life, considering factors such as how many stars are in a galaxy, how many of those stars might be hospitable, how many might have planets, and how many planets might have environments suitable to support life as we know it (or as

[TeleMad]

Yeah, and from your own quote...

"Aczel tackles that paradox after he goes through the statistical calculations for the probability of intelligent life, considering factors such as how many stars are in a galaxy, how many of those stars might be hospitable, how many might have planets, and how many planets might have environments suitable to support life as we know it (or as we don't). Aczel also provides an overview of the relevant developments in astronomy and biology--laying the groundwork to show that the universe's chemistry must add up to life. After teasing readers with scientific history, Probability 1 delivers on its promise to prove Aczel's conjecture through a clearly explained application of known statistical theory to the chaos of the universe.
http://www.mathk-phd.com/probability.htm

He's proving the probability is 1 BASED ON HIS UNSUPPORTED ASSUMPTIONS. See all of the MIGHTs? And what evidence demonstrates that life as we DON'T know it exists? And why is he looking at what environment can SUPPORT life as opposed to what environments can ORIGINATE life?

He's playing with numbers, some of which have no solid basis in empirical science.

Let me give it a try. The standard RNA World theory has life arising as a self-replicating RNA molecule. The closest thing to an RNA replicase produced by directed evolution to date is about 180 nucleotides long (and even it can copy only 14 nucleotides). Even if we assume that a trillion trillion trillion trillion unique sequences 180 nucleotides long could function as RNA replicases, the probability of hitting any one of them in a single shot by the random sequencing of RNA monomers (which we have to assume the environment allows) is still only about 1 in 10^60. What about in multiple shots? Roughly speaking, to have an even chance of success we’d need to have a trillion trillion trillion “shots” on each and every of the approximately 10^20 planets thought to exist in the known Universe: of course, each of those shots on all of those planets would require the same (unlikely) environment that allows random RNA sequences to be pumped out one after another. Worse yet, a single RNA replicase arising by the chance (i.e., undirected) ordering of nucleotides would not suffice since the ribozyme would make copies only of other RNA molecules it encountered, not itself. What is needed is for a pair of RNA replicases to arise at virtually the same instant and in the same microscopic, bacterial-sized volume. Now, how likely is that to occur prebiotically? Something like 1 in 10^120? Now plug that number into Drake's equation and see if the probability still comes out to 1!