February 29, 2016

"Scientists have known for several years now that stars, galaxies, and almost everything in the universe is moving away from us (and from everything else) at a faster and faster pace."

Science: Now, it turns out that the unknown forces behind the rate of this accelerating expansion—a mathematical value called the cosmological constant—may play a previously unexplored role in creating the right conditions for life. By Ilima Loomis

'That’s the conclusion of a group of physicists who studied the effects of massive cosmic explosions, called gamma ray bursts, on planets. They found that when it comes to growing life, it’s better to be far away from your neighbors—and the cosmological constant helps thin out the neighborhood.

'“In dense environments, you have many explosions, and you’re too close to them,” says cosmologist and theoretical physicist Raul Jimenez of the University of Barcelona in Spain and an author on the new study. “It’s best to be in the outskirts, or in regions that have not been highly populated by small galaxies—and that’s exactly where the Milky Way is.”

'Jimenez and his team had previously shown that gamma ray bursts could cause mass extinctions or make planets inhospitable to life by zapping them with radiation and destroying their ozone layer. The bursts channel the radiation into tight beams so powerful that one of them sweeping through a star system could wipe out planets in another galaxy. For their latest work, published this month in Physical Review Letters, they wanted to apply those findings on a broader scale and determine what type of universe would be most likely to support life.

'The research is the latest investigation to touch on the so-called anthropic principle: the idea that in some sense the universe is tuned for the emergence of intelligent life. If the forces of nature were much stronger or weaker than physicists observe, proponents note, crucial building blocks of life—such fundamental particles, atoms, or the long-chain molecules needed for the chemistry of life—might not have formed, resulting in a sterile or even completely chaotic universe. Some researchers have tried to gauge how much “wiggle room” various physical constants might have for change before making the cosmos unrecognizable and uninhabitable.'

"Cosmic Explosions, Life in the Universe, and the Cosmological Constant" by Tsvi Piran, Raul Jimenez, Antonio J. Cuesta, Fergus Simpson, and Licia Verde here

No comments: