Life on other planets

You are also forgetting one other VERY strong possibility. Maybe there is no life anywhere else in the universe?.

The likelyhood of us being alone is miniscule but i guess possibe. How many galaxies are there in the known universe?

How many solar systems exists around a parent star in those galaxies?

The chances of Earth being the only thing in the universe with life on it is remote.

WHY..............why should one little rock like Earth be the ONLY thing in the known universe with life (in any way shape or form) on it?

Thats just silly.....................or maybe its true.

I just dont think we are alone.

Maybe i am just living in fantasy land..........................but i cant see why Earth is so damn special as to be the only place in the universe where there is life.

Til the day i die i will always believe that there is life beyond earth.............we may never know it but i strongly believe in the possibility of it.

WHY should life on any other planet even remotely resemble life on earth. Chances are if it exists it would be so different that we may not even recognize it AS life.

I doubt it, it might not have 2/4 limbs and a head, but if it is alive we'd see it.
Come to think of it why is like on Earth so similar?, it appears that there appears to be only one formula of life that works on Earth, carbon based.
There is a massive about of silicon on the Earth,
Just look a beach and yet to silicon life..

I remember a talk at the Whirlpool a few years back (I cant remember the speaker) but he basically said that nature will arrive at the same answer for an animal no matter its environment or genetics presuming life is favourable, he pointed out as an example the European sabre tooth tiger (mammal) and a sabre tooth in Australia (marsupial), they looked almost identical but were very different once you scratch the surface.

I'm convinced that there has to be life beyond this planet of ours, where is it and what it is poses a question I cannot answer, I hope there is life on Mars (microbial) and I hope it has a radically different genetic make up to us thus proving it originated completely independent of the Earth (all organisms so far discovered on Earth that use DNA use the same code book of genetic base pairs), this would go down as one of the most important discovery of all time.
If it has the same number then maybe we came from a common source or cross contamination occured (Asteroid maybe) some time in the past.

The implications and questions raised by finding life on Mars are enormous.

You are also forgetting one other VERY strong possibility. Maybe there is no life anywhere else in the universe?.

The likelyhood of us being alone is miniscule but i guess possibe. How many galaxies are there in the known universe?

How many solar systems exists around a parent star in those galaxies?

Lots. Then we narrow down the search.
How many of those stars are stable main sequence stars?
How many are in a safe part of the galaxy?
How many are in a single star system?
How many planets are there in the habitable zone?
How many of those planets have a stable orbit? (The Earth needs the Moon to keep the orbit and tilt stable)
How many are large enough to hold onto an atmosphere?
How many of those are small enough to have a low enough surface gravity?
How many have sustained their internal magnetic field?
How many have managed not to go into a runaway greenhouse system?
How many have managed not to go into a big freeze system?

The field gets narrowed down rather quickly.

And in the one system we know with life in it we've only found on one planet. The best chances for us to find life in the universe are on Mars, Venus, Titan and Europa.

DaveL, Simon Conway Morris gave the talk. Great presentation and a great book - Life’s Solution: Inevitable humans in a Lonely Universe.

~Al

Should this forum be renamed "Cosmology, physics and biology"?

I doubt it, it might not have 2/4 limbs and a head, but if it is alive we'd see it.
Come to think of it why is like on Earth so similar?, it appears that there appears to be only one formula of life that works on Earth, carbon based.
There is a massive about of silicon on the Earth,
Just look a beach and yet to silicon life..

I remember a talk at the Whirlpool a few years back (I cant remember the speaker) but he basically said that nature will arrive at the same answer for an animal no matter its environment or genetics presuming life is favourable, he pointed out as an example the European sabre tooth tiger (mammal) and a sabre tooth in Australia (marsupial), they looked almost identical but were very different once you scratch the surface.

I'm convinced that there has to be life beyond this planet of ours, where is it and what it is poses a question I cannot answer, I hope there is life on Mars (microbial) and I hope it has a radically different genetic make up to us thus proving it originated completely independent of the Earth (all organisms so far discovered on Earth that use DNA use the same code book of genetic base pairs), this would go down as one of the most important discovery of all time.
If it has the same number then maybe we came from a common source or cross contamination occured (Asteroid maybe) some time in the past.

The implications and questions raised by finding life on Mars are enormous.

To be honest, i think if life was discovered elsewhere most people would still be more interested in what Britney is up to this week. Id like to be proved wrong, i really would, but i think itll only be the groundbreaking event for a small percentage of Earths population. unless little green men actually land on the White House lawn (and zap georgie bush for a bonus ) i dont think itll make much of an impact. People in general just dont get excited over bacteria/bugs, even it it was proved to be extraterrestrial.

Its one reason why some people (as on this forum) look up at the sky and wonder; yet many people see whats above their heads and never give a second glance or thought to those most profound and soul-searching questions.

I think were the result of an impact of some sort ; as you said life here is eerily similar in development direction. look the the eye of the octopus ; from what ive read its disturbingly close to a human eye. why do we all (the wider animal kingdom) develop in the same general way, ie, head, 2 eyes, forelimbs, rearlimbs, etc etc. Theres a theory that goes Nature, once it finds a good way to do something, will continue to do it that way in future, like a good recipe for a cake.

So the possibility is there that life in the solar system/universe will actually be surprisingly similar to us - forward facing eyes, hands that grip, 2 arms, 2 legs. I dont know. I have a suspicion however that when life is found it may be overlooked - something like the "WOW!" signal. i think a fledging race out there in the cosmos will likely send a simple signal that will be misinterpreted by us as a neutron star / radiation / some other wave.

Hi Paul
These are excellent questions and viewpoints which seem to be a natural progression when people first become interested in astronomy and begin to appreciate how vast the Universe or indeed perhaps the Multiverse is, are we really alone in all this vastness and time? It’s an age old question that many people have tried to answer in so many different ways. Unfortunately (or fortunately depending on your point of view) there is no definite undeniable physical proof of biological material of extraterrestrial origin available that the majority of scientists could study and perform analysis on (not yet officially anyway)! All we currently know and understand, all our knowledge of life and its accepted definition is based upon one planet, as you can gather, biologists are at a severe disadvantage in this field of study if you consider hypothetically speaking another intelligent civilization elsewhere in the MilkyWay galaxy with a billion year head start in technological/social/spiritual evolution capable of studying life in all it guises /stages/evolution basically anywhere in space and time. However, our fledgling science of astrobiology has taken its first steps to perhaps one day answer many of the questions were are asking here and indeed NASA has published a document entitled “NASA ASTROBIOLOGY ROADMAP 2008” which makes for interesting reading; see: astrobiology.arc.nasa.gov/ . At the same time we are still finding new species on earth, we still have unexplored areas on earth, and we still don’t fully understand to 100% how life evolved here and our genetic coding but inroads have been made in varying degrees of discovery and success in all these fields and more.

Over the last 20 years there have been approximately 270 extrasolar planets (ESPs) detected, most of them within a 300 light year radius of the Sun, considering ~10% of the milky way galaxy’s stars are sun like (similar) and that there are ~1000 stars within a radius of the sun of 100 light years that fall into this category, none unfortunately we can say has truly “Earth like” planets, this doesn’t imply that none exists, it just means we haven’t developed the technology to a level were we can easily detect possible Earth like planets with high resolution, however new space missions such as the recent European “COROT” and the “James Webb Space Telescope”, which is scheduled to be launched in a few years will addresses these problems to a certain extent and become the foundation to build upon for near future space missions such as NASA's Terrestrial Planet Finder. If we do find other earth like planets orbiting other suitable and stable stars will these planets contain life as in the definition we know it? One way of detecting life is to measure an Earth like planet transiting its parent star and therefore obtain Spectroscopic measurements to understand the planet's atmospheric composition, if there is oxygen, water vapor, methane, nitrogen etc on this Earth like planet then we should be paying very close attention to it for future exploration when we have the capabilities to do so.
In the meantime of course we have our own solar system to explore and as Dave rightly said “The implications and questions raised by finding life on Mars are enormous” I am sure we would agree that would go for life even in its simplest forms anywhere else in the solar system which leads me on to the meteorite known as “Allan Hills 84001” which was ejected from Mars and ended up on earth long ago. There was much debate regarding this rock over the intervening years but recent studies reported last month on this Mars rock shows that Mars is capable of forming organic compounds at least in its ancient past, in other words the building blocks of life. These findings have paved the way for the “Mars Science Laboratory (MSL), a nuke powered rover mission due for launch in 2009 to ascertain if Mars still holds secrets in this regard.

If we consider the possibility of intelligent life (within the definition as we currently understand) in other parts of the MilkyWay galaxy capable of least rudimentary interstellar communication like us (we have sent deliberate and powerful directional EM signals BTW to nearby target stars already, active SETI rather than passive SETI which has caused some concern for various reasons) to other peoples elsewhere capable of traveling easily between stars, then the question is where are they? Is there so few to zero other civilizations, is that why their deliberate or non intentional signals have not been detected in over 40 years, or are there many civilizations capable of communicating and interstellar travel, then the question must be asked again; where are they? Which leads us into Fermi’s paradox. The Drake equation goes someway to give a number of civilizations within the MilkyWay Galaxy capable of communication, (N). Does N=0 or N=1.0X10^6+, who knows for sure, substituting numbers into the drake equation is best guess based of current knowledge. Other investigations by scientists involved in SETV (Search for Extraterrestrial Visitation) and SETA (Search for Extraterrestrial Artifacts) have perhaps answered Fermi’s paradox in the form of other beings technological manifestations and their detection by us within our solar system including Earth, for a further treatment of these highly interesting investigations and discussions there is another thread that you might be interested in Paul: www.irishastronomy.org/boards/viewtopic.php?t=2078&start=0

“We are Made of Star Stuff”, and “We are a Way for the Universe to Know Itself”, Carl Sagan.

Clear skies
Mike

SETI: www.setileague.org/
NASA's Terrestrial Planet Finder: planetquest.jpl.nasa.gov/TPF/tpf_earths.cfm
COROT Space Telescope: smsc.cnes.fr/COROT/
NASA Planet Quest: planetquest.jpl.nasa.gov/index.cfm
Life: en.wikipedia.org/wiki/Life
Intelligence: encarta.msn.com/encyclopedia_761570026/Intelligence.html
Astrobiology: astrobiology.arc.nasa.gov/
SETV: www.daviddarling.info/encyclopedia/S/SETV.html
SETA: www.daviddarling.info/encyclopedia/S/SETV.html
Mars meteorite: www.sciencedaily.com/releases/2007/12/071211095141.htm