From: Ivan Poupyrev [poup@mic.atr.co.jp]
Sent: Tuesday, August 03, 1999 4:25 PM
To: jpierce@cs.cmu.edu; 3D UI list
Subject: Re: Idea for discussion: violating assumptions

Some quick comments on Jeff's message.

> 6) Gravity
>
> - flying

or simply absense of gravity (following Rob's comment)

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.

> 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.

I can not recall the exact formulation of this principle, but if you
are interested I can dig it up for you, including the reference.

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?

Ivan

--

Ivan Poupyrev . . . . . . . . . . . http://www.mic.atr.co.jp/~poup
poup@mic.atr.co.jp . . . . . . . . MIC Labs, ATR Japan 0774-951432