Don’t reset your watch, but study says Earth took shape more rapidly than once believed
What’s a few hundred million years when you’re talking about the formation of the 4.5- billion-year-old solar system? Quite a lot if you’re an astrophysicist it seems.
Researchers from Israel, the U.S. and Japan are now saying that the nuclear clock used to measure the age of the solar system has been “ticking faster” than previously thought and that the Earth formed much more quickly than originally believed.
“We determined that half life of the geological clock ticks faster,” Michael Paul, a professor of nuclear physics at the Hebrew University of Jerusalem, told The Media Line.
Paul and his team from the University of Notre Dame and the Argonne National Laboratory and two Japanese universities, reexamined Samarium 146, one of the main isotopes used to chart the evolution of the solar system. They found that its half life was only 68 million years and not the 103 million as previously assumed.
“The age of the solar system has not changed. But the time it took to form the Earth as it is at present with its mantel and crust and rocks and so on according to this new measurement is shorter than it was estimated before,” Paul said.
The findings, published in the journal Science, have yet to be accepted by the astrophysicist community. Nor do the findings alter the age of the universe, which is generally believed to have been formed about 4.6 billion years ago.
Measuring half lives of atomic nuclei was first developed in the mid 20th century. Radiocarbon dating was invented in Chicago in the 1940s and has been used to date artifacts by measuring the half life of Carbon 14, which is a few thousand years. But when it came to measuring like the history of the earth and solar system, chronometers with much longer lives were needed.
This particular heavy element samarium-146 was “live” in our sun and solar system when they were born and could be used as “mineral archives” for their slow pace of decay, or half life that could be measured in dozens of millions of years.
“What we determined is that this time scale associated with its half life was shorter than what was estimated before,” Paul said.
According to the research, everything in our solar system formed from star dust several billion years ago. The findings also are significant implications not only for the planet Earth but possibly Mars, the moon and other planets, Paul said.
“These rocky planets have gone through a form of differentiation of their core and a little later of their mantel, which is the outer shell of the planet,” he said. “What is measured with this isotope chronometer is the time scale of this process.”
He said he and his colleagues decided to re-measure Samarium-146 because the previous four calculations that had been made were highly inconsistent and had never been verified. The previously adopted half life was set at 103 million years. Their revised measurement found it to be much shorter at 68 million years, a staggering 30% shorter.
“When we got a result, which was different than what was adopted, we pursued and did a series of confirmation of this measure and published it,” he said.
The project took some four years but, interestingly, the new calculations jived better with the new timescale and seemed to explain previous discrepancies, Paul said.
“It shrinks the chronology of early events in the solar system, like the formation of planets into a shorter time span,” Paul said. “It also means some of the oldest rocks on Earth would have formed earlier – as early as 120 million years after the solar system was formed” rather than approximately 200 million years after.
The Samarium-146 was studied using Argonne’s superconducting linear accelerator known as ATLAS, a machine that shoots beams of subatomic particles in materials to unravel near invisible mysteries.