(photo credit: REUTERS)
Galaxies and stars formed in the universe from ancient gas clouds, contain significant amounts of water, according to research conducted by Tel Aviv University and Harvard University scientists.
The key to the search for other life in the universe is, first of all, water – without which there is no life. Where there’s water, there is a chance of finding life. The discovery that the early universe had much more water than thought until now, means an increased chance of the presence of water – and therefore life – in planets in the vast universe.
“All the galaxies, stars and planets we know today were born out of large gas clouds created in the Big Bang some 13.7 billion years ago,” said Shmuel Bialy, who led the study as part of his doctoral thesis at TAU ’s School of Physics and Astronomy under the guidance of Prof. Amiel Sternberg. “Until now it was generally accepted that the conditions in those primordial clouds prevented the formation of significant quantities of water. In our study we found to our surprise that the amount of water vapor in clouds of gas was much greater than we thought.”
The study was conducted in collaboration with Prof. Avi Loeb, head of Harvard’s astronomy department. The article was accepted for publication in the journal Astrophysical Journal Letters
“When the universe was young, just a billion years old, the stars we know today only began to emerge,” said Bialy.
“Most of the matter in the universe was concentrated in large gas clouds made up mostly of the lightest chemical elements – hydrogen and helium.
The stars, like our sun, and the planets revolving around them were created as a result of the contraction and collapse of clouds of gas – a process that took place billions of years ago and continues today.”
Until now it was generally accepted that the initial gas clouds contained only a small number of water molecules.
There were two reasons for this: “First, the oxygen necessary for forming water was very rare in the early universe,” said Bialy.
“Secondly, molecules that were nevertheless formed in clouds were exposed to ultraviolet radiation [UV]. In today’s gas clouds in our galaxy, the molecules are protected by a large amount of dust, which absorbs the radiation. But this dust was formed only during eons of time, as a product of the creation and explosion of stars. The ancient gas clouds were almost completely free of dust, so the radiation that penetrated them was stronger and more destructive.”
To check how much water was actually in the ancient gas clouds, a research group solved chemical equations that express the rhythm of creation and destruction of water molecules under conditions prevailing in the cloud. “We chose to base the calculation on a theoretical environment in which the amount of oxygen was 1,000 times smaller than we find in gas clouds in our galaxy today,” said Bialy.
“So we expected to find a negligible amount of water molecules, but it was 100 times what we expected. At present, in addition to water vapor, clouds contain a large amount of ice [or water in solid form].”
Wondering why, despite the difficult conditions, the ancient gas clouds formed from a relatively large amount of water molecules, Bialy said the answer lies in the temperature.
“Previous studies by Prof. Avi Loeb and others have shown that in the clouds in the early universe, there was a relatively high temperature, similar to room temperature – about 30 degrees Celsius.
In contrast, the temperature clouds of gas today is very low – below -200 degrees. The cooling was caused by elements such as carbon and oxygen – products of the stars and planets, which were rare in the early universe but are found in today’s clouds. There are plenty of gas clouds today.”
The researchers say that the high temperature accelerated the process of creating water molecules in ancient gas clouds to the extent that it managed to compensate and overcome the impact of radiation and the small amount of oxygen.
“The ancient gas clouds were the raw material from which were created today’s stars and planets,” concluded Bialy.
“So we can assume that the water contained by the clouds found their way to other planets, in our galaxy and other galaxies. It is entirely possible that the conditions for life existed very early in the history of the universe. The greater the amount, the greater the chance of finding life elsewhere in the universe.”
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