Are we alone?

[Brendan Janus]

I thought she only thought that she was?

Your right, she was indecisive back then, but nowadays she's not so sure !!

 

[Seathestars]

I believe alien life is quite common in the universe, although intelligent life is less so. Some say it has yet to appear on planet Earth.

Steven Hawking, good enough for him, good enough for me.

 

[chrismpw]

Also annoys me when it's said water must be present to sustain life.

Says who?

Other life might not need it.

Other life could look at our set of planets and think "Nah, no life there. There's no Zahdyatsm".

I get your point, and once thought the same. It's not until you learn how unique water is that you start to think that, actually, it's a pretty good assumption that, as far as we know, there just isn't a substitute.

Some food for thought:
It's a simple molecule made of two of the most abundant elements in the universe.
It is likely that water is a very common molecule.
It's shape is bent meaning that water is slightly sticky. This means, for its tiny size, it has a melting point and boiling point much higher than it should. This means it can exist as a liquid, rather than a gas, on planets near enough to stars to receive enough energy & warmth to drive chemical reactions - such as, for example, photosynthesis, but far enough away to be away from harmful radiation.
Being slightly sticky means that it can interact with and dissolve a huge range of different substances, such as oxygen, glucose, minerals, CO2 ... And let go of them with little effort. Water dissolves more different substances than any other substance we know of, nothing comes close, meaning it can dissolve the huge range of substances that need to pass into and out of living cells. One day we might make or discover a new chemical that can do the same, but it won't be small and it won't be simple, so it won't be abundant.
Being a tiny molecule means it can pass freely through cell membrane holes, which are small enough to keep big important molecules inside where they take part in the chemical reactions of life.
The only molecule we know of which comes anywhere close to these properties, is ammonia. Ammonia is also common, but it is less sticky, less useful as a solvent, and only liquid farther away from stars where less energy is received, making life (based on solar radiation) less likely.
Two last features of water that is subtly important to life:
1. It's solid form floats on its liquid form. The solid forms an insulating layer which dramatically slows down the cooling of the liquid beneath. Without this, liquid water in oceans would freeze from the bottom up, freezing the entire column of water, acting as a heat sink deterring the water at the top from ever melting again, making it very difficult for life to evolve.
2. Its thermal inertia makes it very hard to heat water up or cool it down. Harder than most other substances we know. This gives life a very stable environment to develop in, which is cushioned from extremes of heat and cold.

So this is why we look for water.

 

[Eggs]

...I think so.

 

[LEONARD]

When trying to explain Koppites, was it not the great Dr Leonard McCoy, who stated?

'It's Life Jim, but not as we know it'

 

[NEWSWEETTOFFEE]

Of course it does.

The universe is so vast we'd be silly to think our spec of dust in that space is that unique.

Note that number of numbers is infinite, but there is only one zero!

 

[Woolly Blue]

I think we're alone now

Deserved more credit that.

 

[paultheblue]

I dont know mate I dont live round here