Centenary of particle pioneer
Cecil Powell won Nobel for discovering the pion and firing up a new
field of physics.
05 December 2003
PHILIP BALL

One hundred years ago today, 5 December 1903, Cecil Powell was born. The
English physicist kickstarted the discovery of a whole zoo of
fundamental subatomic particles.

During the Second World War, Powell developed a technique for recording
the tracks of particles on photographic film. This led to his finding,
with colleagues at the University of Bristol, a new particle called the
pi meson, or pion, in 1947.

For both method and meson he was awarded the Nobel Prize in Physics in
1950.

Powell's winding career path illustrates how early particle physicists
often came to the field from unusual directions. His early work was on
the condensation of steam, and in 1936 he was a seismologist on a
geological expedition to the West Indies.

He started using photography only when he began to study cosmic rays -
very energetic particles streaming from space - at Bristol in the late
1930s.

Read the rest at Nature
http://www.nature.com/nsu/031201/031201-7.html

Envelope physics sheds light on ice sheets
Stick and slip leads to jagged edges, show ripping experiments
02 December 2003
PHILIP BALL

Two physicists in Britain have been investigating why you can open an
envelope cleanly with a paper knife but not with your finger. Similar
ripping processes could explain the formation of jagged edges that
sometimes interleave on adjacent ice sheets.

Animangsu Ghatak and Lakshminarayanan Mahadevan of the University of
Cambridge used rigid rods to rip open plastic sheeting - similar to that
used to wrap compact-disc cases. The rods ranged from about the width of
fuse wire to a sturdy 2.5-centimetre diameter. They were pulled through
the sheet at a constant speed of up to 2.5 cm per second.

For thin rods, tears were straight and smooth. Above a certain rod
thickness, this gave way to a wavy-edged rip with evenly spaced
serrations1. The shape of these teeth is called a cycloid.

http://www.nature.com/nsu/031201/031201-1.html

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Posted by
Robert Karl Stonjek.