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To: HerbVic who wrote (87017)	8/12/2018 2:45:44 PM
From: Stock Puppy	2 Recommendations Recommended By HerbVic Honey_Bee Read Replies (1) \| Respond to of 458182

Even if you go outside our solar system, beyond Pluto. It never gets to absolute zero pressure. There is always some small amount of positive pressure above absolute zero. Who knows how much? Probably something like 0.00000314159 psi, which is minuscule. Herb, great post as usual. You will need quite a few more decimal places for deep space - see below. But I'm sure that you're familiar with this, and if not, it's fun: In any event, pretty good vacuum can be created on Earth, so if materials do funky things at low pressure - well it been tested zillions of times. Check out turbo molecular pumps which can achieve vacuum of 10^-8 Pa ( = 0.0000000000015 PSI or 1.5 x 10^-12 PSI), much lower than the surface of the moon. en.wikipedia.org The problems with materials at low pressure/vacuum is that they start to outgas - stuff in the material goes into the vapor phase. Usually it's adsorbed water and gases. It could also be the material itself - then you don't use it in vacuum! That's a main reason when you flip the switch on a vacuum system it can take quite a while - much longer than predicted by pumping speed - to get down to the pressure that you want - stuff is going into the gas phase. But at some point, especially with carefully selected materials, the outgassing ends and there you are. Finding materials that work well in vacuum is not rocket science. :-) The atmosphere at the surface of the moon is 0.0000003 PSI or 3•10^-7 PSI nssdc.gsfc.nasa.gov Deep space - 0.0000000000000015 PSI or 1.5•10^-15 PSI <- ha! there are your zeros! hypertextbook.com I remember seeing somewhere that deep deep space has something like 10 particles/ cubic meter, but this is from memory... - similar frequency of testing for relativity/time distortion at high speeds/E=MC^2 - they are tested every day and any physicist would love to be the one to disprove! Most established theories are not just some scientist deciding to do a special experiment one day - they are used on a daily basis and any discrepancies would be investigated. That's how the hard sciences chemistry/physics work.