: Wed Mar 11, 2009 12:59 pm  

AdmiralHanson wrote:

Shhhh ! You'll give me away ....

Mate, NOBODY believes you're from this planet!

: Wed Mar 11, 2009 1:20 pm  

AdmiralHanson wrote:

snip

I think to rule out any life on other planet is stupid, and naive

: Wed Mar 11, 2009 1:42 pm  

leicester_rhino wrote:

I think to rule out any life on other planet is stupid, and naive

Not to mention scientifically impossible. Any "rule out" approach would require vastly more information than we have to do it with even modest confidence.

I would rate the probability of being visited by other life as vanishingly small, based on the available information, which may/will be subject to change. I could not begin to rate the probability of life exisiting elsewhere, and nor could anybody else. Whatever equation you use, we don't have enough reliable values to plug in to it to make it meaningful.

: Wed Mar 11, 2009 3:11 pm  

AdmiralHanson wrote:

If we did discover life of any sort on Mars, even microbial, it would have a massive effect on how we thought about the universe around us. If it can 'live' there, then where else could it be that we have previously dismissed as inhospitable ?

One thing I think most scientists would agree on is that life is dependent on one factor more than any other - liquid water. Even on this planet the temperature scale at which life can exist is fairly narrow. There are some tricks bacteria can use to avoid freezing at low temperatures, and they have some unique enzymes that can work and survive temperatures near boiling point (crucial for the development of PCR and producing recombinant proteins in labs) - but all life here needs liquid water. In the universe and our solar system that narrows habitats down a bit. -200 degrees C is not survivable in.
There are a number of alternative metabolic pathways that can allow to exist in an oxygen free state (oxygen is the final requirement for respiration in most life - without it the whole pathway jams up and you can't generate biological energy, but there are substitutes). And there are many sources of external energy - ie volcanic springs at the sea bed. However, once again there are scant few signs of volcanic activity outside the Earth in the solar system.
Europa is an intersting one as it's thought the huge gravitational force it endures creates enough movement in it's ice to generate friction - and thus heat. If there is liquid water there is the possibility of life there of some kind.
But in reality most discovered planets are gas giants, any solid planets would have to fit in an orbit suitable for liquid water to exist - and that narows things down a bit.

: Wed Mar 11, 2009 3:30 pm  

Dave Heron's Moustache wrote:

One thing I think most scientists would agree on is that life is dependent on one factor more than any other - liquid water. Even on this planet the temperature scale at which life can exist is fairly narrow. There are some tricks bacteria can use to avoid freezing at low temperatures, and they have some unique enzymes that can work and survive temperatures near boiling point (crucial for the development of PCR and producing recombinant proteins in labs) - but all life here needs liquid water. In the universe and our solar system that narrows habitats down a bit. -200 degrees C is not survivable in.
There are a number of alternative metabolic pathways that can allow to exist in an oxygen free state (oxygen is the final requirement for respiration in most life - without it the whole pathway jams up and you can't generate biological energy, but there are substitutes). And there are many sources of external energy - ie volcanic springs at the sea bed. However, once again there are scant few signs of volcanic activity outside the Earth in the solar system.
Europa is an intersting one as it's thought the huge gravitational force it endures creates enough movement in it's ice to generate friction - and thus heat. If there is liquid water there is the possibility of life there of some kind.
But in reality most discovered planets are gas giants, any solid planets would have to fit in an orbit suitable for liquid water to exist - and that narows things down a bit.

I would say that the above is very sound logic, but we do not know of what life is like outside our own experiences. On earth life is based on water, and mostly oxygen, but there is nothing to say that in other galaxies around other stars that other rules apply.

: Wed Mar 11, 2009 4:08 pm  

The answer to the question about the ufo last week is simple Brent Webb is back

: Wed Mar 11, 2009 4:09 pm  

roo wrote:

The answer to the question about the ufo last week is simple Brent Webb is back

Like it!

: Wed Mar 11, 2009 4:13 pm  

leicester_rhino wrote:

On earth life is based on water, and mostly oxygen, but there is nothing to say that in other galaxies around other stars that other rules apply.

I agree. There is nothing in our biology or chemistry research to suggest that other rules apply elsewhere in the universe.

: Wed Mar 11, 2009 4:13 pm  

Dave Heron's Moustache wrote:

I agree. There is nothing in our biology or chemistry research to suggest that other rules apply elsewhere in the universe.

true, but why would we research the possibility of life based on consuming platinum only for example? As a race I think we have an inability to think beyopnd what we see / witness.

: Wed Mar 11, 2009 4:31 pm  

Dave Heron's Moustache wrote:

It's called the Drake equation and is explained here by Carl Sagan.

Loved 'Contact' one of my fave films.