From: Jeff Pierce [jpierce@cs.cmu.edu]
Sent: Tuesday, August 03, 1999 7:24 PM
To: 3D UI list
Subject: Re: Idea for discussion: violating assumptions

At 05:25 AM 8/4/99, Ivan Poupyrev wrote:
>In fact, the absence of gravity is quite useful in most VR
>applications since it allows to freely manipulate objects in space
>using only one hand and clutching. Imagine what would happen if
>objects kept falling down every time you released them and there
>were no second hand.

Note that what we've actually got now is slightly different than the lack
of gravity.  If I let go of something, it doesn't drop to the floor.
However, the object also loses any velocity that I've imparted to it.  So
we've got a combination of no gravity and no inertia.

>> 16) Objects cannot occupy the same space
>>
>
>Actually, this assumption has been formulated by Leibnitz about 200
>years ago and has been argued about in literature on metaphysics
>ever since. The principle states that if any two objects occupy 
>exactly the same place in time and space then there would be only
>_one_ object, not two.

Luckily virtual worlds aren't governed by metaphysical theory.  =)


>BTW, going back to Leibnitz, he also proposed a theory that we live
>in "the best of all possible worlds". Therefore, according to this 
>theory copying the existing, physical world would be the way to go.
>It does not seem to work in VR, however. Any comments?

Leibniz was actually talking about the Multiple Worlds hypothesis, though,
wasn't he?  If you throw Schrodinger's Cat in a box, there are two possible
worlds: one where the cat is dead, and one where it's alive.  When you open
the box, you collapse the possibility space to a single world.  However,
the Multiple Worlds theory says that both worlds exist: a world where you
find the cat alive and a world where you find the cat dead.  Leibniz
basically argued against the Multiple Worlds hypothesis on the basis that
God would only allow the best possible world to continue.

Of course, my metaphysical theory was awhile ago.  =)

Jeff