Subject:
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Re: Home-made One-way valve
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 20 Dec 2001 21:46:31 GMT
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Viewed:
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1375 times
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In lugnet.robotics, sjbaker1@airmail.net writes:
> Duckie Dave wrote:
>
> * When you take more air out, do you get more vacuum?
> * If you double the size of a tank containing a fixed amount of
> air, do you have more vacuum or the same amount?
> * If you maintain that there is *some* vacuum stored in your Lego tank
> when it is at half normal atmospheric pressure, how much vacuum is
> there in the air we are breathing?
> * At what pressure can we say there is catagorically no vacuum present?
> * If there is no vacuum stored in a sealed vessel at one atmosphere here
> on Earth - will it somehow gain some vacuum if we take it to someplace
> on Jupiter where the ambient pressure is 10 atmospheres?
> * Does the vacuum leak out of the sealed tank if we take it up to the top of
> Mount Everest?
>
> The whole concept of vacuum as a tangiable 'thing' that you can "store"
> is just silly. Like Phlogistron was to the ancient alchemists or 'The Ether'
> was to pre-Einsteinian physicists.
>
> You may argue that it's only a matter of terminology - akin to the mythical
> "centrifugal force" that upsets physicists so much...but fuzzy thinking does
> not belong in a scientific pursuit such as robotics - and we should endeavor
> to stick with the correct way of viewing the world.
>
> Just because we talk about 'Vacuum Pumps' and 'Vacuum Cleaners' doesn't
> mean that the terms have physical meaning. Scientists also use the term
> 'Centrifuge' even though they know that these machines work by momentum
> rather than by some peculiar force that operates on objects that move
> in a circle.
If you had a 1 atmosphere vacuum in a blue LEGO tank and you took it to the
bottom of the Mariana Trench you would have about 13,000 atmospheres of
vacuum in it. And if you took it out into space you would have *no*
atmospheres in it. All this becomes more sensible when you consider that
vacuum is not a measure of quantity (cf farads) but state (cf volts). If
you are ok with negative voltage you should be ok with vacuum.
Are you comfortable with the fact that, when you close the refrigerator door
you get negative light? Do you think there really is 'antimatter' in
physics? And what do you make of ...ice-cubes... is it negative heat?
Jerry (while wondering if the bubbles are 'negative beer')
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Message is in Reply To:
 | | Re: Home-made One-way valve
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| (...) Argh! <rant> It's been a long time since domestic lightbulbs were even partially evacuated - these days they are filled with some kind of relatively inert gas. Back in the 1940's and 50's they were partially evacuated - and on some old movies (...) (23 years ago, 20-Dec-01, to lugnet.robotics)
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