Evening star., 1939-09-02
Of Stors, Men
And Atoms
Notebook Of Science Progress
In Field, Laboratory
And Study

In Field, Laboratory
And Study
BY Thomas r.. Henry.
Measuring extraordinarily minute
amounts Of the sun gas, helium, trapped
in the shattered shrapnel Of some ancient
star explosion in cosmic space, scientists
cooperating with the National Re-
search Council are estimating the age
of creation.
Their results indicate that the age Of
the whole system Of stars, or at least
that part Of 1t from which the iron
meteorites come, is only q little greater
than the earth-about 2.0O0, 900 900 years
according to Dr. Alfred c. Lane, chair
man Of the Research Councils Commit-
tee on Geological Time.
The estimates are made possible by use
OF such sensitive electrical devices that
it is possible to detect fractions of a
cubic centimeter Of the gas in ton Of
rock.
The most commonly used method for
estimating the age of rock Is the So
called popcorn" system The radio
active elements, uranium and thorium,
slowly disintegrate into lead, throwing
out helium atoms in the process. The
rate of disintegration is known. Conse-
quently the ratio Of lead to the radio
active elements in any particular SAM
pie OF rock indicates the time that has
elapsed since 1t was formed.
+ The helium content of the rock should
give an independent measurement, were
it not for the fact that the light gas
leaks out Of the rocks. This is not the
case, however, with iron. It is almost
impervious to helium leakage, and a
great number of the Shooting stars"
which hit the earth from outer space
are composed largely of this element.
Says Prof. Lane: Methods of meas
uring extremely small quantities of
helium have been developed. Their
principle Is the same as that which
makes an electric light 60 out when the
bulb Is broken. A very fine wire going
through vacuum tube conducts elec-
tricity, but 1t is very sensitive to the
lmperfection of the vacuum. A few
atoms allowed to leak into the vacuum
will make difference in its conduction
of heat and electricity.
Using helium detectors based on this
principle the accumulation of gas in
meteorites and radioactive minerals
has been obtained in quantities almost
too small to imagine. 1t is possible to
detect fractions of the cubic centimeter
of helium in ton of rock, or hundred
hundred millionths Of a gram of radium
in a gram Of rock.
--latest estimates of the age of the
earth based on this method give maxi
mum Of 2,800o00,OOO years. The uni
verse itself probably is not much older.
Some OF the meteorites studied which
give about this same figure are not even
from the solar system but from cosmic
space. Their ages may give some sort
OF clue to the age of the universe as
whole, for which definite beginning
Is indicated
The estimates Of the age of the mete-
orites are only little higher than the
estimated ages of the worlds oldest
rocks, which come from near Winnipeg,
Canada. They are found, however, in
rocks which are believed to be still older,
but which do not lend themselves to
scientific experiments that will indicate
their age. The rocks studied show an
estimated antiquity of / ,722 900 900 years.
1T is not unsafe to say that the age
Of the earth is about 1000 900 900 years
or more"
The work of the National Research
Council Committee is a cooperative
project in which laboratories all over the
world participate. One of the great
difficulties still is the separation of differ
ent types Of lead. There are several
varieties which result from the radio
active disintegration of uranium, actin
ium and thorium, the most common ex-
ploding elements, and each variety differs
slightly in atomic weight from the ordi-
nary lead which is believed to have been
formed independently. This in the past
has made some of the estimates subject
to very great efforts.
"hdt 10 dCIudiiy measured is tne tlme
which has elapsed since the material
which made up the rocks came together
with the cooling of the earth The
popcorn" method gives no clue to the
length of time the materials may have
existed in the parent sun before they
formed part of the matter torn loose
from it by the close approach of some
other star