Testing for life
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Testing for life
A question I've been thinking about, I think it was featured in New Scientist: What would be a reasonable experiment to test whether something was alive or not? (Taking into account that we don't actually have a definition for 'life' yet!)
True, what about viruses, they are on the borderline. A lot of people regard them as life that can be killed, but some say it isnt life. A definition of life still has to be known if you want to know if you have just ceased the function of a very complex mineral (what some people regard viruses as being), or have killed a living organism.
Terrestrial because we can't be sure what limitations this environment had on the development of some features.
Is cellularity probably common? Yeah, but it might not be a "deal-breaker" feature if you're deciding Life or Not Life.
Personally, I think viruses are descendants of some of the earliest terrestrial life, from the precellular period. Definitely Life. But many disagree, for various reasons.
Is cellularity probably common? Yeah, but it might not be a "deal-breaker" feature if you're deciding Life or Not Life.
Personally, I think viruses are descendants of some of the earliest terrestrial life, from the precellular period. Definitely Life. But many disagree, for various reasons.
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This is intensely interesting, and is the crux of Biology for me.
All the suggestions so far given, while excellent, can be applied to many things or argued against. Think about this.
I refer you all to the work of Lovelock, who asked the same question. "How do we know there is life on Earth?".
In short, and even this has intense criticism, the test for life is simply this: energetic disequilibrium.
Think about the atmosphere of Mars - this is chemically balanced according to the physics that govern the gases (etc.). Now consider Earth's atmosphere: there should simply not be 21% Oxygen in the atmosphere under 'normal' circumstances - its absurd. The chemical is highly reactive and frankly dangerous.
I may appear to be talking nonsense here, but I urge you to consider this thoroughly. "Life fights chaos".
(But I particularly like 'poke it with a stick')
All the suggestions so far given, while excellent, can be applied to many things or argued against. Think about this.
I refer you all to the work of Lovelock, who asked the same question. "How do we know there is life on Earth?".
In short, and even this has intense criticism, the test for life is simply this: energetic disequilibrium.
Think about the atmosphere of Mars - this is chemically balanced according to the physics that govern the gases (etc.). Now consider Earth's atmosphere: there should simply not be 21% Oxygen in the atmosphere under 'normal' circumstances - its absurd. The chemical is highly reactive and frankly dangerous.
I may appear to be talking nonsense here, but I urge you to consider this thoroughly. "Life fights chaos".
(But I particularly like 'poke it with a stick')
"What are humans if they don't learn at University? Animals, yes."
^^One of my ex-girlfriends said that. I stress the ex part.
^^One of my ex-girlfriends said that. I stress the ex part.
St.NorbertBiologyStudent wrote:Doesn't all life respond to some type of stimulus?
If not, what living organism doesnt respond to some sort of stimulus?
Yes but how do you find a "correct" stimulus? I can poke bateria for hours with a stick without seeing any evidence of reaction. But If I had some glucose to their Minimal medium, I will be able to see something.
Now identifying the stimulus that will collect a life like response from alien life form might be hard to identify.
The criterion offered by Kotokeru seems better.
Patrick
Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)
Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)
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