Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: IAMREALITY on 22/07/2016 20:23:30
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I've always wondered this... How the temperature range found in the universe is so immense, from just above absolute zero to trillions of degrees celsius; yet life will generally only thrive in what, like a 200 degree range? That's like .0000000028 of a %. That's kinda insane to think about right?
But why, if atoms can obviously handle such an incredibly large range of temperatures, would life, which is nothing but a collection of atoms at the end of the day, be so delicate, to only be able to handle .0000000028 of a % of the universal range?
Kinda a weird question, but just a curiosity.
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In a somewhat different context, I recently heard a cosmologist talking (http://www.bbc.co.uk/programmes/b07jyrdg) about the "ridiculously strong anthropic principle" (or words to that effect). The idea that "I will only consider theories that dictate my observations to date".
His argument was that you at least need to keep other theoretical possibilities on the table, even if you haven't observed them at this stage.
Our sole experience and observation of life to date is based on observations of 1 planet (Earth), and most of those observations have been within a couple of kilometres of the surface of the Earth. Life here is based on water-soluble organic chemicals, which only occur in a limited temperature range from slightly below 0C (in very salty water) to slightly above 100C (in pressurized water).
Based on this experience, exobiologists are eager to explore other places where liquid water may also exist - on Mars and Europa, for example. We are looking for "life as we know it".
Our limited experience does not rule out other kinds of life.
But I do think we would have a hard time recognizing other kinds of life, even if it were right under our noses.
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All of what we call life depends on self-replicating molecules. The process of accurate mitosis is only possible if the conjugate parts of the molecule are weakly bonded to each other and individually composed of relatively rigid components.
Think of a zip fastener: the teeth are rigid, so can only bond to their conjugate teeth and not, for instance, the teeth of a bigger zip, but the support structure is flexible so you can join two independent parts into a single unit.
In the case of DNA, the bases ("teeth") are sterically rigid over a small temperature range and the inter-strand bonding (hydrogen bond) can only break and re-form accurately within the temperature range of liquid water. Thus we find creatures living around undersea smoke vents where the hydrostatic pressure allows water to remain liquid at high temperatures, and active arctic bacteria contain chemicals that lower the freezing point of water, but the overall range is, on a cosmic (or even terrestrial) scale, very small.
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Life has many layers of atomic structuring. It is composed of atoms which are sturdy at high temperature. The atoms are combined into molecules, which can then polymerize into macro-molecules. These are sturdy but within a narrower temperature range. These then assume secondary, tertiary and quaternary shapes, held together with weak binding forces.
As we go from atoms all the way to quaternary shapes, the temperatures for stability get narrower since the binding forces get weaker and more subtle. The narrow temperature range for life is connected to the needs of the weak binding forces that hold together the secondary, tertiary and quaternary shapes. If these shapes are not within their narrow specs, enzymes won't work. If we heat a protein and denature it, it will never do anything again. The atoms, molecules and polymers remain viable, but loss of shape is devastating.
Water plays an important role in the structuring in life, because of its ability to form four hydrogen bonds. This allows the water to bind to organics as well as form extended water structures; clusters. The energetically favorable self ordering of water, which is also binding to organics, helps force order into the secondary, tertiary and quaternary shapes of the organic molecules. Protein in air, or in any other solvent, will not fold properly, since these all lack the push of water.
As a working example, if we mix oil and water, the self binding of water is so energetically favorable, that the oil beads up and separates out to minimize the potential of water. If we boil water and oil, oil will now become soluble in the steam; called steam distillation. If fact an oil that boils at 250C will boil off with water at 100C. The water as steam, which is no longer self binding, begins to alter the binding forces of the oil so its boiling point goes down as ti solubilizes. Once the water and oil cool, the water becomes active again, in another more self binding way, which forces the oil back into spheres. Life is at the sweet spot where water can induce perfect folding of protein; probability= 1.0.
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I've always wondered this... How the temperature range found in the universe is so immense, from just above absolute zero to trillions of degrees celsius; yet life will generally only thrive in what, like a 200 degree range? That's like .0000000028 of a %. That's kinda insane to think about right?
But why, if atoms can obviously handle such an incredibly large range of temperatures, would life, which is nothing but a collection of atoms at the end of the day, be so delicate, to only be able to handle .0000000028 of a % of the universal range?
Kinda a weird question, but just a curiosity.
I'm not sure that this is a valid analysis. There is a much larger range of pressures in the universe (more than 50 orders of magnitude between intergalactic space and the core of a neutron star), and yet life is only known to exist between 10–2 and 103 atmospheres of pressure (0.0000000000000000000000000000000000000000001 of a % of the universal range)
The universe contains "objects" as small as 10–15 meters (a proton) to 1025 meters (the largest known large quasar group) while known organisms only span a range of 2x10–7 meters (small bacteria) to 4x103 meters (largest fungus known) --> 0.000000005 %
etc.
Also, as others have pointed out, there is a strong bias here, in that we can only observe life on Earth (which has a fairly small range of temperatures and pressures)