[meteorite-list] F.A. Paneth - Radioactive Decay Processes and theAge of Meteorites

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Sun, 22 Mar 2015 04:57:58 -0500
Message-ID: <884189.36654.bm_at_smtp112.sbc.mail.gq1.yahoo.com>

Guys,

Paneth is writing this in 1928
because that is when George Gamov
worked out the quantum mechanics
of radioactive decay, particularly
of the uranium and thorium series.
Paneth is merely appreciating the
possibilitie.

There are dating possibilities
because, while all the radioactive
decay serieses end in good old
long-lived lead, lead has several
isotopes (same atomic number;
different atomic weights caused
by hitch-hiking neutrons).

This is called lead-lead dating.
However, measuring the exact
abundances of lead atoms by
isotope is tricky. You need to
measure very long-lived elements
if you're going date something as
old as the Earth, but the longer
the half-life of an element is, the
more difficult it is to measure!

This was first done by geochemist
C. C. Patterson (and George Tilton).
Cleverly, he measured the lead-
lead ratios in meteorites AND in
ocean bottom sediment (which
would contain a samples of lead
eroded out of all the Earth's
surface for hundreds of millions
of years.

Bingo! Both extraterrestrial lead
ages and terrestrial lead ages were
essentially the same for the formation
date of the solar system and the Earth:
4.55 +/- 0.070 10^9 years.

Here's his 1956 paper:
http://www.colorado.edu/geolsci/courses/GEOL5700-9/pdf/Fall07/Patterson.pdf

Measuring both values answered
Paneth's question: "In our present
state of ignorance of how they were
formed, we must admit the possibility
that there may be meteorites
substantially older than the oldest
strata on Earth..."

Jumping all the way back to George
Gamov... He was not only a great
physicist, but a very good popular
science writer. A Russian, he managed
to wiggle out of the Soviet Union and
come to the U.S. only a little behind
Einstein wiggling out of Germany
(both in 1933).

In the 1930's, Gamov worked out the
basics of neucleosynthesis in stars.
In 1940, he wrote a book, "The Birth
and Death of the Sun" on the process
of element creation in an early hot
universe and the evolution of stars.
Today, this is called "The Big Bang
Theory," although he never called it
that. But he's it's Father of the Big
Bang..

In 1952, Gamov was re-printed as a
early news-stand paperback book
(paperback books were a brand-new
thing then), and I still have my
63-year-old copy bought with my
school lunch money.

I'd buy two milks and save the rest
of the lunch money for books, the
same way I bought Arthur C. Clarke's
first book "Interplanetary Flight" that
same year. It was much more slimming,
as it was a hard-bound book and had to
be paid for in advance because it would
have to be imported by boat from far-away
England. (This is how to be a complete
geek yet not get fat.)

In Gamov, writing in 1940, I learned
(because measuring the half-life of lead
isotopes was so hard, hence imprecise)
that the crust of the Earth was 1.6
billion years old and that the planet
and the solar system could not be
much more than 2 billion years old.

By 1955, when Life magazine published
their famous "The World We Live In"
book (still worth looking over, BTW),
they described the dating of the age of
the Earth and Sun as "never less than
2 billion and never more than four or
five billion years." I guess the long
half-lives of the lead isotopes was in
the wind or they'd heard about C. C.
Patterson's as-yet unpublished work.

He published the next year, and in
the 60 years since, there has been no
contradictory evidence found for that
dating. Geochemists can get a good
fight going by suggesting shifting the
date by 10 or 20 million years.

Evidence converges on Patterson date:
the Earth's oldest "rock," the tiny Jack
Hills zircon is 4.404 +/- 0.008 x 10^9
years old. And the lunar sample, the
"Genesis Rock," dates to 4.460 x 10^9
years.
http://www.psrd.hawaii.edu/April04/lunarAnorthosites.html

Evidence from two worlds...

Sterling Webb
---------------------------------------------------
-----Original Message-----
From: Meteorite-list [mailto:meteorite-list-bounces at meteoritecentral.com] On
Behalf Of Galactic Stone & Ironworks via Meteorite-list
Sent: Saturday, March 21, 2015 9:14 PM
To: rickmont at earthlink.net
Cc: Meteorite List
Subject: Re: [meteorite-list] F.A. Paneth - Radioactive Decay Processes and
theAge of Meteorites

Hi Rick and List,

Our knowledge of meteorites has changed a great deal since 1928. :)

Best regards,

MikeG

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On 3/21/15, rickmont at earthlink.net <rickmont at earthlink.net> wrote:
> Notwithstanding any uncalculated (our inability to do so) time anomaly,
> bringing in the ol' Relativity question.   To what degree is this a valid
> consideration?
>
> -----Original Message-----
> From: Galactic Stone & Ironworks via Meteorite-list
> Sent: Saturday, March 21, 2015 4:01 PM
> To: Meteorite List
> Subject: [meteorite-list] F.A. Paneth - Radioactive Decay Processes 
> and theAge of Meteorites
>
> "As is well known, the most exact way of determining the ages of rocks 
> depends upon the regularity of radioactive decay processes. Obviously, 
> the same method can be applied to meteorites... In our present state 
> of ignorance of how they were formed, we must admit the possibility 
> that there may be meteorites substantially older than the oldest 
> strata on Earth..."
>
> ---> F.A. Paneth (1928)
>
> Uber den Helium Gehalt und das Alter von Meteoriten, Z.Elektrochem, 
> Vol. 34, pp. 645-652
>
>
> --
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Received on Sun 22 Mar 2015 05:57:58 AM PDT