Re: are we alone in the universe?
 

I think that it is almost statistically impossible for Earth to be the only planet that has life on it. Now there may not be other life forms in our galaxy, but there are sure to be some somewhere at some other infinitesimal part of the universe. On the second slide from this powerpoint presentation given by my astronomy professor for next semester really shows how large the universe is when compared to the Earth. Really, the universe is beyond HUGE, and contains billions and billions (if not more) stars, and with many of those stars come planets, however the vast amount of these cannot be seen from Earth.

And I'd also like to bring up another point to add to the discussion. In every case that I have seen, scientists look for signs of water that would be able to sustain alien life. But who says that these life forms are dependent on water? Given a completely different planet with a completely different set of environments, I think it would be possible that the life on that planet would develop so that it actually lives off some completely different natural resources. It could be that a planet is inhabited by life that lives off of Helium in the air and some kind of Jello for food. Then we have a nice planet of squeaky-voiced Bill Cosby aliens.

Also, it may be that alien life forms have or will exist. Given the great amount of time that the universe has been around and probably will be around, all life forms on a planet may have already died out, or are just coming into existence. The possibilities truly are endless.

However, given the size and scope of the universe, I believe it to be very unlikely that we will ever come in contact with any such civilization, because it would take nothing short of science fiction to allow for such beings to travel the great distances of space to just-so-happen to pass by our planet.

My 2.5 cents ;)

Re: are we alone in the universe?
 

Maybe we can somehow generate and extremely massive electromagnetic storm so that if any other intelliegent beings are out there we could let them know that we are here. Didn't at one time the US have like 70,000 nukes. Maybe they still do. What if we sent them way out to space and blew them up all at once to make a signal of our presence.

Re: are we alone in the universe?
 

I hate posting things I can't explain and things I am not very knowledgeable about, but I wanted to throw this into the mix:

Astronomers have calculated stars seemingly to be older than 16 billion years old. They can not explain how a star can be older than the universe itself. How could it have existed before the calculated time before the big bang? Its like having a child older than its grandmother.

Re: are we alone in the universe?
 

Here's the problem as I see it. As has been mentioned previously and numerous times, the universe is very big. I'll add that it's also very old. In terms of astronomy, Earth is only +/- 4.4 billion years old. I saw a special on either the National Geographic channel or the Discovery channel a few months back which chronicled the development of the Earth from debris field to the formation of our solar system, to the development of life. According to the show, the earliest signs of life on Earth showed up only a few hundred thousand years after the planet formed. They were simple bacteria, and helped process the hydrogen and carbon dioxide rich atmosphere into the oxygen we all know and love. What's not yet known is what kicked off the reaction which led to the amino acids to form into bacteria.

The problem is humanity has developed the tools to help observe and understand the nature of the universe only in more recent years. The telescope was invented around 1608, and computers and space telescopes have only really been in service since the early 90s. (Hubble was in development since 1977, but wasn't launched until 1990). So, for all intents and purposes, humanity has really only had eyes in the sky since 1608, and the ability to track stellar events since the early 90s. So we have roughly 400 years of data. Out of the 16 billion year old universe, we've only been watching it for 0.000000025% of it's existence. That's like watching 1/125th of a single frame of a 2 hour movie on TV (at 30fps). Of course, we can apply our knowledge of physics as we know it and extrapolate approximate positions, speeds, distances, etc. based on what we see. But what we see now is less than a fraction of what's happened/happening out there. Add to that the problem of the speed of light, where what we see from the other side of the galaxy happened thousands of years ago, and the picture becomes a bit murky. Add in a dash of the human lifespan, and we have a pretty good recipe for misconceptions and misunderstandings.

It took until the late 1400's for people to understand the world was round instead of flat, and the 1500's to find out the Earth rotated around the Sun. That's roughly 500 years ago. Space is a new frontier we're only beginning to explore and understand. Things like dark matter and anti-gravity particles have yet to be definitively discovered, and for all we know there could be structures of even more curious things floating around up there. Therefore, at this point any equations are based on a number of unconfirmed variables.

Also, the assumption that all life is based on DNA is a bit presumptuous. They key words are "life as we know it." Like Ken, I don't want this to become a religious debate, but let's say for the sake of argument that life on earth did start from a spontaneous chemical reaction, producing bacteria which then evolved into higher life as conditions became more favorable. Given that if all life rose from simple amino acids and then bacteria, it only makes sense that all life here would share the same structure in DNA. However, the theoretical existence of silicon based life-forms means there may be life in places carbon-based life couldn't possibly survive. In any case, my feeling is there's really not enough data either way to draw any sure conclusions. My personal feeling is we are not alone. Perhaps more advanced civilizations have visited our solar system at one point, or still do. If they have, maybe they consider our species to be too primitive, selfish, and greedy to make any meaningful contact worthwhile. I'd also guess if they have the technology to travel between stars, they would have the capability of hiding themselves from our relatively primitive telescopes.

Re: are we alone in the universe?
 

if there are 10,000 earth like planets in our galaxy, then the odds are 1:10,000 that any given planet is the single origin of life

if we came here from somewhere else, then either we were involved in that transfer (as a species) or it was done by a species more evolved than us, and we were just cargo along for the ride.

But I think if we were going to colonize another star system, I cant think of any reason to send only one-cell organisms. I would send the most complex life forms we could, including humans if humans can survive on the new world.

so from what we know about earths biological history - tens of millions of years of life existed before humans showed up. Therefore, if we came here from somewhere else there must have been a very long program of first seeding the planet with plant and animal life, and then after 50 million years or more we came here too (after the earth was ready) ?

We only assume humans evolved from other lifeforms here on earth, because there is no other explaination based on what we have found here on earth. But if we came here from another world, then we dont know our own history as a species

which would be very strange.

we dont really know. Unless we find a starship buried under the pyramids Im inclined to believe we evolved here, and we are the only life in the galaxy.

Re: are we alone in the universe?
 

that ratio of 1:10,000 isn't any good lets say you add all the neighboring universes then your ratio could be 1:,100,000 and the actual ratio might end up being 1:1,000,000,000,000,000,000,000,000,000,000,000 (and actually i wouldnt be surprised if thats right)

Re: are we alone in the universe?
 

I believe that I saw some article a few months back that said something about there being some form of clay that actually, when reacted with water (I think) it creates amino acids.

Re: are we alone in the universe?
 

this is what I meant when I said the astronomers have not been talking to the bilogists. When Darwin first proposed that single cell organisms could easly assemble themselves in primortal soup I dont think we even knew about atoms and molecules yet (I will have to double check this). To Dawin a single cell organism was simple, a handfull of elements mixed together.

but we know know that a one cell organism is incredibly complex - and we can put a number on that complexity (how many atoms or molecules there are, and how many possible combinations)

so while the universe is very large (1E66 atoms in the universe), the most simple life forms are way more complex (1E350 possible combinations to get one cell correct)

Re: are we alone in the universe?
 

actually we know exactly how they are made and are even able to create them in labratories by simulating earths environment (not with some fancy machine) and chemicals present at the time. the word Atom comes from the greek word Atomos which was basically thought to be the smallest particle of matter. however no real knowledge came until Rutherford and the plum pudding model which comes after Darwin.

Re: are we alone in the universe?
 

it may seem presumtuous at first, but DNA based life is the only form of life in existance on the earth, the moon, on Mars - everywhere we have been able to investigate so far

and its incredibly complex. If simpler life forms could exists then probability says they would have spontaiously been created long before DNA life would, and there would be billions and billions of different life forms - all based on different molecular arrangements

but we find none, nothing here, only DNA life

now if lifeforms other than DNA based can exist, but they are more complex than DNA, then the probability equations hold true for them. They would be even more unlikely to spring into existance spontainously than we were

so (according to statisics) they are not out there either.

Re: are we alone in the universe?
 

you are correct, but the complexity of 1E3 is not the complexity of life based molecules (DNA)

the complexity of the most simple DNA is 1E350, and as I explained on the wesite, every single atom everywhere (universe) times every single second since the big bang only gets you to around 1E100.

Re: are we alone in the universe?
 

we are able to create amino acids in the lab, yes - but there are countless variations of amino acids. Most of them are tar like substances and are toxic.

To build one DNA strand every molecule, every atom has to be in the right place, or the DNA cannot reproduce, and it would not be suitable for life.

the fact that we can create amino acids in the lab is like taking 1 million dice and throwing them all on the floor - yes we can throw them, but we cant make them all come up 6 at the same time

we cant fabricate DNA from the raw elements

Re: are we alone in the universe?
 

However.... i think certian material made today merit attention. there are materials with a "memory" for their shape. i know it may not merit much at first glance but neither would amino acids to an alien. also if their is life like us than they probably wont be the ambasidors for their kind. look at our robotic research is the human race that far a way from giving birth to a mechanical life. and if so will they have a glowing red light that goes back and forth accross their faces. yes deep questions are these. and in responce to the last post the statment was that we didnt know how amino acids were created not DNA.

Re: are we alone in the universe?
 

it becomes a chicken/egg problem. DNA based single cell organisms can take oxygen, carbon, hydrogen... and build its own amino acids, its own protien strands, and create a complete perfect copy of itself

but anything less than that one cell organism cant - cant build any of the molecules needed

so that puts you back down to random chance - back to the 1E350 probability of it happening at random

it only has to happen at random once, in the right place, and the spark of life is ignited. All life on the planet can be the result of that one spark

but it has to happen spontainiously at least once.

Re: are we alone in the universe?
 

first of all viruses can be considered to do those things and what i ment was i was responding to the statement that we didnt know how amino acids were created.