Evening star., 1951-08-01
Micro-Wutch Used
By Atomic Scientists
Age Of Earth Now Measured
200 Times More Precisely
By Thomos R. Henry

micro-watch of millenniumS, by
which the age of the earth and its
mountains can be measured with 200
fold increase in efficiency, has been de-
Veloped by Atomic Energy Commission
scientists
The standard time measure of the
distant past is the so-called uranium
lead ratio in rocks Uranium 238, the
most abundant form of this exploding
element, breaks down through the
cons into rare form Of lead. Any Of
this lead found anywhere once was
uranium. Half of any given amount
of uranium will change to lead in about
5 billion years.
The rate Of this breakdown has
been precisely calculated Hence the
amount OF the lead isotope compared
with the amount of uranium in any
specific rock gives fair indication OF
its age.
For the oldest rocks on earth, pre-
sumably formed at about the time the
planets crust hardened, the age turns
out to be approximately billion years.
This agrees fairly well with astronomi-
cal calculations.
D1fnculty SurmOunted.
The difficulty has been that 1t has
been necessary to find rocks containing
measurable amounts of lead and ura-
mum. With the new method of analysis
less than five-millionth of an ounce
OF the lead isotope is required for ac-
curate calculations. Hitherto, a mini
mum at least 200 times this amount
was considered essential before any re-
lance could be placed in the estimates.
The method can be used with rocks
containing less than one part in a
million of uranium.
1t is like lady's wrist watch COM
pared with a grandfather's clock.
The method already has been used
with two samples of the lead isotope
extracted from petrified bones in the
Colorado Plateau area in an effort to
get some clue to how the Colorado
uranium deposits originated. Such data
may assist in exploration for new ore.
The refinement introduced by the Oak
Ridge scientists, it is expected, will make
it possible to tell the age, in thousands
of years, of many geological features,
such as mountains which thus far have
been able to keep their millenniumS
secret. Uranium, in extremely minute
amounts, Is distributed generally through
rocks all over the earth.
X
Making a solid of creations rarest aa1
has just been reported by scientists EN-
ployed by the Atomic Energy Commits
sion.
This substance is Helium 8, form Of
the sun gas" which results from atomic
disintegration, and which has several re-
markable properties. 1t seemed to defy
the known laws of nature by refusing to
solidify.
Other gases, as temperature is reduced,
first become liquid. Then. like water.
the liquid freezes. Even ordinary helium
appeared to contravene this law. Helium
"ice" could be formed only when high
pressures were applied at very low tenn
peratureS.
The amount of the new form of helium
possible to obtain hitherto has been too
minute to permit much experimentation.
There is only millionth as much Of it
on earth as of ordinary helium. Scien-
fists at the Atomic Energy Commissions
Argonne laboratory in Chicago were
able to obtain minute supply due to
the fact that it occurs as decay
product of radioactive hydrogen-the
"tritium" which has been mentioned as
an essential for the proposed hydrogen
bomb. The total amount used was so
small that solidification was carried out
in tubing about the thickness Of
human hair.
Edge of Absolute Zero.
First it was necessary to reduce the
temperature to 457 degrees below zero
Fahrenheit. This is just on the edge of
absolute zero, the ultimate of cold in
creation, where all molecular motion
stops and matter becomes completely
dead. Then a pressure equivalent to
500 pounds a square inch was applied.
Quite suddenly the nearly microscopic
amount of liquid turned to ice.
Calculations showed that this could
not have occurred without pressure even
at absolute zero itself. The helium
would have remained a super-cooled
liquid.
This finding is of considerable sig
nificance. it is announced by the Atomic
Energy Commission, because Of the new
light it may throw on the forces operat-
ing within the nucleus of an atom.
Meanwhile, the Commission has ex-
planned, scientists working under an
Acc contract at Ohio State University.
are approaching temperature of only
a thousandth of degree above absolute
zero. The ultimate of cold never will be
attainable.