24/7 Space News    Physicists Find Extra Dimensions Must Be
Smaller Than 0.2 Millimeter  A torsion pendulum with 10 holes is
suspended by a tungsten fiber so thin it is barely visible in
the photo. The pendulum hangs less than a millimeter above a
rotating plate that also has 10 holes. The plate exerts
gravitational twist on the pendulum that is measured by bouncing
a laser beam off a mirror at the top of the pendulum. (UW Photo
by Mary Levin) Seattle - Feb. 19, 2001 University of Washington
scientists using gravity measurements to hunt for evidence of
dimensions in addition to those already known have found that
those dimensions would have to occupy a space smaller than 0.2
millimeter.  In making that finding, the team headed by UW
physics professors Eric Adelberger and Blayne Heckel gained new
insights into gravity. One of the biggest mysteries in physics
is why gravity is so weak compared with all other natural
forces. A small magnet suspended above a table, for instance,
can easily overcome the downward g