Re: negative springs

> From: "John A. deLaubenfels" <jdl@adaptune.com>
> Subject: Chopin goes unstable
>

There was SOME program I was playing with once where I had the
same sort of idea as negative springs and stabillity and I made
the spring 'push' at small displacements but be overcome by a
'pull' at large displacements. like f = x^2 - 1/10x^4 or some
such. Then, since all it wanted to do was oscillate, there
needed to be a damper (shock absorber)... can't remember the
details of that particular fudge... I probably read the Schaums
Physics book chapter on springs and dampers and then kludged
something that almost worked right.

I'll definately look into your musical application, it sounds
like fun.

Oh, the reason I responded was I heard recently that negative
gravity had been proven and that that was why the universe
is flying apart faster the further it spreads. Where normal
gravity increases its attraction inversel square of distance,
negative gravity increases its repellence as the square of
distance.

This behavior is the opposite of the active spring I
dsescribed above.

Bob Valentine

[Bob Valentine wrote:]
>There was SOME program I was playing with once where I had the
>same sort of idea as negative springs and stabillity and I made
>the spring 'push' at small displacements but be overcome by a
>'pull' at large displacements. like f = x^2 - 1/10x^4 or some
>such. Then, since all it wanted to do was oscillate, there
>needed to be a damper (shock absorber)... can't remember the
>details of that particular fudge... I probably read the Schaums
>Physics book chapter on springs and dampers and then kludged
>something that almost worked right.

Sounds like fun! So I'm gathering you were doing a time-history,
keeping track of location and velocity?

>Oh, the reason I responded was I heard recently that negative
>gravity had been proven and that that was why the universe
>is flying apart faster the further it spreads. Where normal
>gravity increases its attraction inversel square of distance,
>negative gravity increases its repellence as the square of
>distance.

I remember reading about negative gravity in the news recently; they
didn't give any numbers. But increasing repellence as the square of
distance sounds awfully extreme! I'd like to know more...

JdL