The news has set the flying-saucer-sphere abuzz with the thought that other planets in the universe are therefore more likely to have had water, at some stage at least, and to therefore have developed life.
That however is not claimed by the paper published in Science Magazine on September 26, when life forms in Israel were celebration the new Jewish year.
“It isn’t news that water in the solar system is older than the sun,” explains Prof. Morris Podolak of Tel Aviv University’s Department of Geosciences, an expert on planetology and the evolution of comets: it had to be. What is news is that the water on earth cannot have originated in the protoplanetary nebular disk from which the planets, including Earth, formed.
It all started with the big bang
Current thinking is that the universe began with the big bang, which created mainly hydrogen and some helium, Podolak explains. “Things like oxygen and other heavier elements were made in secondary processes, like inside stars, which threw out the material. Our sun is second-generation, made of material that originated with an earlier generation of stars,” he says.
In other words, our sun was formed already including heavier elements such as carbon and oxygen made after the big bang but before the sun’s birth, Podolak explains.
Moreover, the universe has a huge amount of hydrogen, a lot of helium and the third most prevalent element is oxygen, says Podolak. Water consists of hydrogen and oxygen (two hydrogen atoms to one of oxygen, to be accurate).
So the interstellar void in which the solar system, and Earth, formed had water bobbing about that would by definition be older than the sun. We would expect water to be abundant in that void, says Podolak.
The weird thing discovered by the team headed by Ilsedore Cleeves of the University of Michigan’s Astronomy department is that the water on Earth doesn’t have the same chemical signature — deuterium-to-hydrogen enrichment — as primordial water in the solar system. Nor could processes in that disk have created the signature of the water on earth, the team says. So the question is where it came from.
Comet collisions or water-locking rocks
To this day the origin of water on earth remains a mystery. Some believe our oceans are actually the result of a lot of collisions by icy comets with the primordial planet, which eventually brought sufficient ice to create our oceans. Another theory is that the iron and silicate rocks that formed our planet had water in their molecular mesh. The new discovery does not necessarily tie into the comet theory better than the inside-rock-all-this-time theory, says Podolak: Theoretically the primordial water could have combined with silicates to form hydrated minerals.
However water got to earth, it’s older than the sun and solar system — which are believed to be between 4.5 billion and 5 billion years old.
“Identifying the source of Earth’s water is central to understanding the origins of life-fostering environments and to assessing the prevalence of such environments in space,” write the authors, led by Ilsedore Cleeves of the University of Michigan’s astronomy department, who has been researching the origins of planetary systems.
So water is out there in the interstellar void, as a corollary of the universe’s evolution. If our solar system is not unique in this respect, “and there’s no reason to think it is,” says Podolak, then there’s water out there in interstellar space, and theoretically other planetary systems — they have been proven to exist — could have formed with water on board too. And hence, perhaps, maybe, they have life.
Present thinking cannot conceive of life forming in a nonwatery environment, because for molecules to knock about and accidentally create life (if we may oversimplify a tad), they need an environment that enables movement. Think of tossing golf balls into a filled pool as opposed to a sand trap. In the pool, they’ll move around and knock against each other, possibly reacting; in the sand trap they’ll just sit there until a life form from elsewhere lobs them out again.
But it remains a leap to conclude that since there’s water in space, life must exist elsewhere in space too. Maybe it does. Maybe life on Earth is a cosmic accident. Man still has no clear idea how he came about, let alone the proto-ameba that gave birth to all beings, assuming there was only one. For all we know there were multiple proto-amebas and life forms spring up all over the place and some survive and some do not.
Ruth Schuster
www.haaretz.com
29/9/14
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