Mindforth

Richard S. Norman rnorman at umich.edu
Tue Dec 10 18:08:10 EST 2002


On Mon, 09 Dec 2002 23:08:47 -0500, Jerry Avins <jya at ieee.org> wrote:

>"Richard S. Norman" wrote:
>> 
>> On Mon, 09 Dec 2002 20:01:57 -0500, Jerry Avins <jya at ieee.org> wrote:
>> 
>> >Gary Bergstrom wrote:
>> >>
>> >> > > jmdrake wrote:
>> >>
>> >> > http://www.americanantigravity.com/
>> >> >
>> >> > While on the surface it may seem "cranky" the fact is that their
>> >> > flyer actually works.  Now if it works by true "antigravity" or
>> >> > by some other force is a big question.  But the plans are pretty
>> >> > simple and the results have been reproduced many times over.
>> >> > However someone might mislabel them "cranks" just because they
>> >> > have the word "antigravity" in their URL.
>> >> >
>> >> > Regards,
>> >> >
>> >> > John M. Drake
>> >>
>> >> The first time I saw this was on the cover of a Popular Science (I
>> >> think) in the '60s.  Not antigravity, just propulsion by moving air.
>> >> The models are so light, because it's hard to move much air without
>> >> arcing.  (That old model on the cover was square rather than
>> >> triangular, but otherwise looked the same!)
>> >>
>> >> And yes, I would label (NOT mislabel) them cranks because of the word
>> >> antigravity.
>> >>
>> >> Gary
>> >
>> >Waddya mean, "cranks"? Antigravity devices are all around us. I'm typing
>> >right now on a keyboard a little higher than my lap. You can bet that
>> >gravity would pull it down pretty quick it there weren't something
>> >preventing that. The same goes for what's holding me up. Those things
>> >must expend energy continuously to do what they do. If you think that
>> >there can be no work without motion, just hold a full gallon jug still
>> >with an extended arm and tell me that it's only hard to do if it moves.
>> >
>> 
>> Yes, I will tell you: there is no work without motion (or the
>> equivalent for non-mechanical forms of work).  Your muscles can get
>> very tired without doing external work.  You can push against a stone
>> wall all day, even a metaphorical stone wall, and exhaust yourself
>> without doing one erg of external work.
>> 
>> "Hard to do" does not require work in the technical physics sense!
>> 
>> Technical terms have technical meanings, whether you like them or not.
>> Antigravity has a specific meaning. It means it eliminates or reduces
>> gravity, not simply supports an object or elevates it against an
>> unchanged gravitational force. And anyone who claims to work with
>> antigravity is deserving the label "crank".
>
>Excuse me please. I hadn't realized that the message was cross posted.
>Those who know me realized that I was attempting humor. I'm sorry to
>have failed. (I got As in all my physics courses, going back to 1948 in
>high school.)
>
Oops, sorry!  I didn't catch the sarcasm.

Unfortunately, there are far too many people quite capable of writing
what you did in complete sincerity.





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