Did Alien life thrive in the Big Bang afterglow? 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. 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.
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 stellar furnaces in this massive cluster of galaxies shown in the image at the top of the page had transformed light elements into heavy ones. In the image, individual cluster galaxies can be seen at optical and near-infrared wavelengths, shown in red, yellow, and green colors. X-ray data (in purple) reveal the hot intracluster gas, enriched in heavy elements.
The galaxy cluster lies nearly 9 billion light-years away ... and so existed at a time when the Universe was less than 5 billion years old. A measured mass of more than 200 trillion Suns makes this galaxy cluster the most massive object ever found when the Universe was so young. The cluster elemental abundances are consistent with the idea that most heavy elements were synthesized early on by massive stars, but current theories suggest that such a massive cluster should be rare in the early Universe.
The Daily Galaxy via Nature 504, 201 (12 December 2013) doi:10.1038/504201a and arxiv.org/abs/1312.0613
Image credit: APOD, Rosati (ESO) et al.; X-Ray: CXC, NASA / Optical: ESO, VLT