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Author Topic: Is there an ideal "gravity" for life to exist?  (Read 1499 times)

Simon Pringle

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Is there an ideal "gravity" for life to exist?
« on: 26/07/2015 15:36:32 »
Simon Pringle asked the Naked Scientists:
   
Kepler has found a planet 60% larger than size of the Earth, this could mean it's gravity is 60% stronger. This turn would imply that its "atmosphere" would be very different from that of the earth - but could this still suggest that some form of earth like life forms? i.e is there a " gravitational zone " for life forms as there is a " habitable zone ". Indeed, do you know what the range for the " habitable zone " including gravitational zone is? What these parameters are?

Many thanks,
Simon
What do you think?
« Last Edit: 26/07/2015 15:36:32 by _system »


 

Offline alancalverd

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Re: Is there an ideal
« Reply #1 on: 26/07/2015 16:29:46 »
Aquatic life can be adapted to pretty much any gravitational field by altering its mean density. We know that aquatic life exists on earth at almost all temperatures within the liquid range of water.

Assuming that any recognisable life form will use DNA or something similar - i.e. a selfreplicating molecule held together by hydrogen bonds - we can therefore assert that any planet with liquid water can sustain life and probably does, did, or will. 
 

Offline chris

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Re: Is there an ideal
« Reply #2 on: 26/07/2015 21:35:00 »
Great point Alan.
 

Offline evan_au

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Re: Is there an ideal
« Reply #3 on: 26/07/2015 22:26:38 »
There is still considerable uncertainty about planets discovered by the transit method - it gives the size of the planet, but doesn't tell you about its atmospheric composition. (Planets discovered by the stellar Doppler shift method have even greater uncertainties...)

This latest discovery could be an Earth-like rocky planet, a planet covered entirely by water, or it could be a mini-Neptune, a small gas giant.

In the hydrogen/helium/methane atmosphere of a gas giant, the density increases with depth, to the point that the density is comparable with the density of water, and could potentially support atmospheric life (although the chemistry of such life would be quite unlike anything found in our oxygen-rich atmosphere).

On the "lighter" side of gravity, bodies less massive than the Earth would tend to lose their atmosphere to stellar winds, which would make surface life as we know it impossible. However, icy moons like Europa could hide a habitable zone beneath their icy crust, with effectively no atmosphere above the crust.

Assuming you had a big hollow spaceship I see no reason why air-breathing life could not live in free fall, providing you had a way to distribute light around inside it, without having plants block all the windows. 
 

Offline Bored chemist

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Re: Is there an ideal
« Reply #4 on: 27/07/2015 14:21:40 »
I wonder how many life-forms have come up with an idea something like this.
"This is rather as if you imagine a puddle waking up one morning and thinking, 'This is an interesting world I find myself in an interesting hole I find myself in fits me rather neatly, doesn't it? In fact it fits me staggeringly well, must have been made to have me in it!' This is such a powerful idea that as the sun rises in the sky and the air heats up and as, gradually, the puddle gets smaller and smaller, frantically hanging on to the notion that everything's going to be alright, because this world was meant to have him in it, was built to have him in it; so the moment he disappears catches him rather by surprise. I think this may be something we need to be on the watch out for.
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Re: Is there an ideal
« Reply #4 on: 27/07/2015 14:21:40 »

 

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