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.

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.

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

Like it!

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.

Loved 'Contact' one of my fave films.

Carl Sagan was a master of communication, one of my favourite scientists. "The Cosmos" was as enthralling as "Life On Earth". I think that film was spoiled though by the religious thread that ran through it - although it's in the book also I think. I think Sagan was an agnostic, but hadn't his wife just died or soemthing when he wrote it? I can't remember.

Actually our ability to see and think beyond observation is the principle defining characteristic we have compared to the rest of the animal kingdom. You just defined the human race. Theoretical physicists, biologists (like me), chemists, artists, base a huge chunk of what they do on things they have never seen or may actually never observe.

which team do you think is most likely