(NOTE: What wonders we have 'tulpoided' into existence...what will we discover next...?E.)

Invisible asteroids might endanger Earth
Friday, 9 March 2001 13:44 (ET)
http://www.vny.com/cf/News/upidetail.cfm?QID=166615
(Posted here for discussion purposes on this forum.)

Invisible asteroids might endanger Earth

MELBOURNE, Australia, March 9 (UPI) -- Invisible asteroids and other
cosmic bodies made of a new form of matter may pose a threat to Earth,
asserts a noted Australian physicist.

Robert Foot of the University of Melbourne claims a meteorite composed of

mirror matter -- a form of the invisible dark matter that many say makes up
over 95 percent of the universe -- could impact the Earth without leaving
any fragments.

Indeed, he told United Press International, asteroids made of mirror
matter may have been responsible for such cataclysmic events as the
so-called Tunguska blast, which destroyed acres of Siberian forest in 1908.

While scientists generally attribute this explosion to a meteorite, no
traces of such an object have ever been found.

However, "mirror matter would be undetectable in our ordinary matter
surroundings," Foot told UPI in a telephone interview.

Foot believes mirror-matter asteroids might be a greater danger than
normal asteroids.

"These objects may pose an overall greater risk than space bodies composed
of ordinary matter," Foot said. "An approaching space body made of pure
mirror matter would not be detectable -- only after impact with the
atmosphere would its effects be observable, but then it would probably be to
late to do anything."

Mirror matter, Foot claims, arises naturally from two apparent symmetries
of nature. One says matter is unchanged whether it moves forward or backward
in time; the other, that nature doesn't distinguish between right- and
left-handed orientations.

"These particles must exist if the symmetries exist," Foot said.

In the invisible universe of mirror matter, Foot explained, space and time
are reversed. Time moves backward and right-handed spatial coordinates have
been interchanged with their left-handed counterparts.

Something in the visible universe that is sitting at 50 degrees north and
20 degrees west as the clock ticks toward the future would have an
invisible, identical counterpart at 50 degrees south and 20 degrees east as
the clock ticks toward the past, according to Foot's theory.

Invisible forms of matter that preserve symmetries are nothing new to
physicists. Nobel Laureate Paul Dirac predicted that anti-matter must exist
to preserve certain symmetries of matter. His prediction was borne out with
the discovery of positrons, the anti-matter form of electrons.

Princeton physicist Howard Georgi is skeptical of Foot's claims, however.

"Robert Foot's ideas are interesting," Georgi told UPI. "They are also, of
course, extremely speculative."

Georgi also believes that invisible asteroids are not a top priority of
physics research.

"Foot's ideas have not attracted a huge following in the community that
cares about these things, perhaps because the problems they solve, while
interesting, are not the most critical puzzles that we are wrestling with,"
Georgi said.

(Reported by UPI Science Writer Mike Martin from Columbia, Mo.)