Could Alien life have exsited in the Big Bang afterglow? According to Abraham Loeb, an astrophysicist at Harvard University, in the early Universe, the energy required to keep water liquid could have come from the cosmic microwave background, the afterglow of the Big Bang, rather than from host stars. A set of calculations -standard adiabatic cold dark matter (ACDM) cosmology- suggests that the first star forming halos within the Hubble volume started collapsing at redshifts allowing liquid water chemistry— a prerequisite for life — to form on rocky planets just 15 million years after the Big Bang regardless of their distance from a star. “The whole Universe was once an incubator for life,” he says.
The first light produced by this plasma is the cosmic microwave background radiation (CMB) that we observe today, which dates from about 389,000 years after the Big Bang. Today, the CMB is terrifyingly cold — around minus 454 degrees Fahrenheit (minus 270 degrees Celsius; 3 degrees Kelvin). It cooled down gradually with the expansion of the universe, and at some point during the cooling process, for a brief period of seven million years or so, Loeb's "vast habiytable zone," the temperature was just right for life to form — between 31 and 211 degrees Fahrenheit (0 and 100 degrees Celsius; 273 and 373 degrees Kelvin).
Our current understanding of the early distribution of matter is incomplete, says Loeb. Standard Big Bang cosmology says that in most parts of the universe, the amounts of heavy elements needed to make planets didn't occur until hundreds of millions of years after the big bang. But rocky planets could have existed in pockets of the early Universe where matter was exceptionally dense, leading to the formation of massive, short-lived stars that would have enriched these pockets in the heavier elements needed to make planets. He suggests that there would have been a habitable epoch of 2 million or 3 million years during which all rocky planets would have been able to maintain liquid water, regardless of their distance from a star.
"These planets are very rare objects that are extremely unlikely, but because the universe is so large, you could still have them," Loeb says. These planetary systems would have to be very stable from a very early stage to give life a chance of emerging.
Many of our greatest scientists have been asking why does the universe appear to be "fine-tuned" for life? The logic behind this question, sometimes known as the anthropic principle, says that's why we are here today, able to study the universe and learn about its laws, that the fundamental constants in the universe are tuned in just the right way for us to be around to observe them. But if any of these constants were slightly different, we could never have come in to exist in the first place.
"The anthropic argument gives us an excuse for not seeking a more fundamental understanding," says Loeb, which makes the notion of "big bang life" appealing. The denser regions of matter needed for it to arise would have also required a cosmological constant a million times larger than ours. That would mean life existed in our universe even at a time when the value of the cosmological constant would have precluded the existence of humans, negating the anthropic thesis.
Christopher Jarzynski, a biophysicist at the University of Maryland, reports the journal Nature, is not convinced that life could exist in a uniformly warm Universe. Life on Earth depends thermodynamically not only on the heat source of the Sun, but also on the cold cosmic microwave background, which provides a heat sink, he notes. “Life feeds off this,” he says.
Alexander Vilenkin, a cosmologist at Tufts University, issued the most logical hole in the Loeb hypothesis "that a few million years is too short a time to produce intelligent life." And the statistical odds of it happening are so low, and that most life in our universe should be suited to today's small cosmological constant, that from a statistical view the anthropic principle remains valid.
The image at the top of the page shows an extraordinarily dynamic galaxy cluster, MACS J0717.5+3745, with a total mass greater than 1015 (a million billion) times the mass of the sun or more than 1,000 times the mass of our own galaxy appears to contain three relatively stationary subclusters (A, C, and D) and one subcluster (B) that is being drawn into the larger galaxy cluster, moving at a speed of 3,000 kilometers per second. By observing a high-speed component of this massive galaxy cluster, Caltech/JPL scientists and collaborators have detected for the first time in an individual object the kinetic Sunyaev-Zel'dovich effect, a change in the cosmic microwave background caused by its interaction with massive moving objects.
The Daily Galaxy via Nature 504, 201 (12 December 2013) doi:10.1038/504201a and http://ift.tt/1jvqXW9
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