Chair of the Astronomy Department at Harvard Says Other Complex Life in Universe Very Possible

Abraham (Avi) Loeb an American/Israeli theoretical physicist who works on astrophysics and cosmology and is Chair of the Astronomy Department at Harvard says that “it’s quite possible that life is everywhere and we are the late-comers”. Today Forbes released an article that summarizes a paper submitted by Avi Loeb to the journal of Astrobiology. The entire article can be viewed below.

The following passage comes directly from Forbes (Note I have bolded certain key points)

   The evolution of complex life in the universe has, heretofore, thought to have been quite a long slog.

But in a paper submitted to the journal Astrobiology, theoretical cosmologist Avi Loeb argues that some form of complex life may have arisen within the first billion years of our universe’s existence.

Loeb, Chair of the Astronomy Department at Harvard, says that some fraction of the cosmos’ first so-called Population III stars may have produced supernovae that seeded the early cosmos with large amounts of metals, like iron. Such heavy elements, Loeb notes, are crucial when forming terrestrial planets like our own.

These first stars — thought to on average have been some 100 times more massive than our sun — likely had hydrogen-burning lifetimes of only 3 million years. Yet Loeb says a follow-on population of Population II stars that formed within these very first stars’ metal-rich vicinity, could have spawned earthlike planets, some fraction of which may have harbored complex life.

“These were stellar “islands” enriched by heavy elements where you could make planets,” said Loeb. “But most of the early universe either had pristine [hydrogen] gas or low metallicity gas.”

The Cosmic Microwave Background (CMB), relic radiation leftover from the Big Bang, was roughly room temperature when the universe was only 15 million years old.

A rocky planet at such early times, wouldn’t have needed the warmth of its parent star, but Loeb says could simply have bathed in the CMB’s radiation, which for some 3 million years at least could have allowed for planetary liquid water and, in principle, the chemistry of life.

And if that prospect isn’t tantalizing enough, Loeb says conceivably tens of millions of years after the Big Bang, Population II stars could have also had metal-rich proto-planetary disks capable of forming earth-like planets.

These longer-lived Population II stars would have provided stable long-term conditions for these young earths and may have led to life as we know it literally near the dawn of time.

Theoretical Cosmologist Avi Loeb.  Credit:  CfA Public Affairs

Cosmologist Avi Loeb

In his paper Loeb also says that even in a cosmos that had an initial high value cosmological constant, or energy density of the spacetime vacuum, complex life would have still had time to evolve within the first one billion or so years of the universe’s ex

istence. That is, before this accelerating vacuum energy caused space to expand so rapidly that gravity could not have done its work and galaxies like our Milky Way — rife with stars and planets like our own — could not have formed.

To date, however, the standard paradigm for the evolution of intelligent life in the universe is that if it’s out there, it’s probably only been around for the last 6 billion years, or about a billion years after the peak of cosmic carbon production.

But what if life did evolve on an earth-like planet circling an early Population II star?
One born only 50 million years after the Big Bang?

If it vectored into intelligence that somehow persisted over much of the universe’s 13.8 billion-year history, by now such an ancient civilization’s technology would arguably be nothing short of “godlike.”

firststars

Simulated Image of the Universe’s first Stars

“The picture that we have of the [early] universe is that the cosmos is sort of dead,” said Loeb. “But it’s quite possible that life is everywhere and we are the late-comers.”

 

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