"Cecil Moore" wrote in message
. net...
http://news.independent.co.uk/world/...cle2134891.ece

If the theory is correct, exotic matter occupies space in such a way that
sometimes enough of it gathers through gravitation attraction to create
"mass" and form a particle that suddenly appears and then quickly
disintegrates after perhaps a nanosecond of existence. Effectively,
particles pop in and out of existence in space.

To describe what exotic matter "is" during the majority of its time when it
does not exist as particular mass depends on what the definition of "is" is.
(Hmmm, I heard that quotation somewhere ;-))