Evening star., 1947-05-04
New Physics Prineipl,
Raises Shock Wave
Effect Of Explosives
By Thomos R. Henry
Science Editor of The s,ar

mathematical physics which may in
crease by as much as so per cent
the shock wave effect Of high explo-
siyes, including atomic bombs, was
revealed yesterday at meetings here
of the American Physical Society.
This principle shows that the ef-
feet of such shock waves is greatest
when they hit a target at less than
a 9o,degree angle--that is, to destroy
target the aim should be to one
side rather than directly at it.
For this discovery DR.. John Won
Neumann, Of the Institute of Ad-
vanced Studies at Princeton Uni
versity, has been awarded the Medal
of Merit, the Governments highest
civilian decoration. 1t was known
during the closing days Of the war,
but whether any actual use was
made of it could not be revealed
Pressures Built Up.
Early in the war, it became ap-
parent that greater effects In total
destructiveness could be produced by
shock waves than by direct hits. The
principle is that enormous densities
of pressure are built up in front of
a rapidly moving object and these
strike target like a solid, moving
wall. It was recognized early that
the shock effect was twice as great
as would be calculated from the
force OF the original explosion. This
depended on the principle that the
forces of action and reaction are
equal and opposite, the same prin-
ciple that causes gun to kick back
against the shoulder.
Won Neuman's discovery that the
kick back" could be enormously in
creased by indirection depends on
extremely complicated mathemati-
cal principles and equations which
were essentially unavoidable until
the advent of the super lculating
machines developed under Army
auspices during the war.
The fact remains, 1t was explained,
that the way to destroy an object
other than through the purely local
effects of direct hit is not to hit
1t. The principle would be appli-
cable to all air bombing.
Atomic Shock Wave Differs.
The triple effect of the original
shock wave has been demonstrated
for relatively weak explosions. It
Is the maximum yet achieved.
Whether the effect for an atom
bomb is as great could not be re-
vealed.
From the atom bomb, however,
has come new type of shock wave
essentially series of air explo-
sions- due to the great heat waves
which come from such an explosion
with the projection of temperatures
OF millions of degrees. For all
ordinary explosions a shock wave of
certain energy is set up which
diminishes constantly the further
removed it is from its source. With
the atom bomb this original wave
constantly is built up by new blasts
along its path, the whole moving
with something less than the We
locity of light.
A person in the path of such a
wave first would feel the heat from
the explosion and an instant later
feel distinct blow, the strength
OF which would depend on the
distance fromathe point of explosion.
These findings were revealed in a
press conference of the Physical
Societyis Committee on Fluid Dy-
namics, the field which embraces the
study OF shock waves. :. I
Supersonic Research Set.
For the first time in this country,
1t was revealed, it soon will be pos
sible to study the effects of such
waves moving faster than the speed
of sound and this may have far
reaching implications not only in
the use of explosives but also for air
craft travelling at transsonic speeds.
The speed Of sound is approximately
760 miles an hour at sea level, but
varies greatly with air temperatures
and densities Several supersonic
wind tunnels are being constructed
but the only one near completion at
present Is at the Naval Ordnance
Laboratory at White Oaks, Md, just
outside Washington. This was taken
intact from the German scientific
sation at Peenemunde Island in the
Baltic and several German scientists
now are aiding In its adaptation to
present problems.
Greatest stress was laid on super
sonic experimentation in Germany
during the war, to the detriment of |
the enemy's efforts to produce an
atomic bomb. This work was nee
essary in rocket development.
A hitherto unknown type of air !
pressure waves from an explosion
from 200 to 300 miles away was de-
scribed before the society today by
Everett F. Cox of the Naval Ord |
nance laboratory These can de-
tected by delicate barometers and
eventually may make it possible to
locate explosions at great distances.
Thus it might be possible to detect |
explosion of an experimental atomic !
bomb by an enemy.