Philip Lacroix |
04-05-2016 09:41 AM |
Quote:
Originally Posted by OregonJim
So much of science is self-fullfilling prophecy - science suggests a theory, and then manipulates the pre-conditions such that the theory holds 'true'. This is necessarily so, as much as you wish to deny it, since science cannot consclusively prove the state or condition of things that occured in the distant past (...)
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It is not "necessarily so". Of course one has to start from somewhere, i.e. the present, however this is not as limiting as you seem to think. Regarding the concentration on nitrogen in the ancient atmosphere, as in your question, you can analyze minerals for example, and look for traces of water:
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Understanding the atmosphere's composition during the Archean eon is a fundamental issue to unravel ancient environmental conditions. We show from the analysis of nitrogen and argon isotopes in fluid inclusions trapped in 3.0 to 3.5 Ga hydrothermal quartz that the PN2 of the Archean atmosphere was lower than 1.1 bar, possibly as low as 0.5 bar, and had a nitrogen isotopic composition comparable to the present-day one. These results imply that dinitrogen did not play a significant role in the thermal budget of the ancient Earth and that the Archean PCO2 was probably lower than 0.7 bar.
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Source: Nitrogen Isotopic Composition and Density of the Archean Atmosphere (Abstract)
Regarding the same paper:
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«We were looking for rocks that might have preserved a record of the ancient atmospheric composition, and found quartz crystals that contained minute, micron-sized fluid inclusions that had trapped and preserved 3.5 billion-year-old fossilized water», said lead author Bernard Marty of CRPG-CNRS. «Analyzing extracted gases by mass spectrometry allowed us to identify ancient atmospheric gases, and to derive the atmospheric pressure of nitrogen (N2) at that time was similar to, or even lower that, that of the present-day».
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Quote:
«This measurement shows that Earth's environment did not change drastically over the last several billion years, a stability that was necessary on our planet to permit life to flourish», said Marty. «Carbon has been pivotal to maintain such clement environmental conditions at Earth's surface for several billion years».
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Source: Nitrogen Concentration in Earth's Archean Atmosphere
Also, at astronomical scales the fact that the speed of light is limited makes an excellent time machine, hence you can actually see things (and not just in the visible spectrum) that happened billions of years ago, and analyze them as if they were happening today (with spectroscopy for example). One possible assumption? Well, you should assume that the laws of physics themselves didn't change over time, but apparently there's no element suggesting they did, which is nice.
Quote:
Originally Posted by OregonJim
(...) science cannot consclusively prove the state or condition of things that occured in the distant past - it must make assumptions based on how things are in the present. And much of what happened in the distant past is the foundation for what science considers to be 'fact' now. Catch-22.
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Regarding the first sentence, science can prove such things, as I tried to show by some examples. Overall, you're creating a paradox where there is none. Of course if you're looking for an absolute perfection then you should stick to a religion, but I'm not sure it is a good idea if you want to understand how nature works.
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