To LUGNET HomepageTo LUGNET News HomepageTo LUGNET Guide Homepage
 Help on Searching
 
Post new message to lugnet.roboticsOpen lugnet.robotics in your NNTP NewsreaderTo LUGNET News Traffic PageSign In (Members)
 Robotics / 16794
16793  |  16795
Subject: 
Re: Home-made One-way valve
Newsgroups: 
lugnet.robotics
Date: 
Thu, 20 Dec 2001 21:46:31 GMT
Viewed: 
1510 times
  
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')



Message is in Reply To:
  Re: Home-made One-way valve
 
(...) 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)

23 Messages in This Thread:








Entire Thread on One Page:
Nested:  All | Brief | Compact | Dots
Linear:  All | Brief | Compact
    
Active threads in Robotics

 
Contact Recovery Nerd for Speedy USDT / BTC Recovery
17 hours ago
Custom Search

©2005 LUGNET. All rights reserved. - hosted by steinbruch.info GbR