Astrophysicists Identify the Habitable Regions of the Entire Universe

KentuckyFC writes It's not just star systems and galaxies that have habitable zones--regions where conditions are suitable for life to evolve. Astrophysicists have now identified the entire universe's habitable zones. Their approach starts by considering the radiation produced by gamma ray bursts in events such as the death of stars and the collisions between black holes and so on. Astrobiologists have long known that these events are capable of causing mass extinctions by stripping a planet of its ozone layer and exposing the surface to lethal levels of radiation. The likelihood of being hit depends on the density of stars, which is why the center of galaxies are thought to be inhospitable to life. The new work focuses on the threat galaxies pose to each other, which turns out to be considerable when they are densely packed together. Astronomers know that the distribution of galaxies is a kind of web-like structure with dense knots of them connected by filaments interspersed with voids where galaxies are rare. The team says that life-friendly galaxies are most likely to exist in the low density regions of the universe in the voids and filaments of the cosmic web. The Milky Way is in one of these low density regions with Andromeda too far away to pose any threat. But conditions might not be so life friendly in our nearest knot of galaxies called the Virgo supercluster."

Comments

A few hundred extrasolar planets

[i kan reed]

And suddenly you can start extrapolating on the whole damn universe. I like how science works like that. You start having an understanding of something, and you can use that in conjunction with the theory that best predicted it to suddenly have a pretty good guess about everything else.

It's the nice reality of science compared to the complaining about it a couple threads down.

Sure the theory's wrong, but we don't know how yet, and our guesses are just so much better than they were a decade ago.

Re:A few hundred extrasolar planets

[i kan reed]

No one "assumed" that. There's a fuck-ton of evidence for the big bang and universal expansion. And the current model is a reaction to that information.

Off the top of my head:
1. Cosmic microwave background radiation matching what the models suggested there would be had the universe expanded from a singularity
2. Redshift of distant objects being proportional to their distance
3. Overall concentration of elements heavier than those produced in a super-nova matching expected levels for the super-high energy environment immediately following the big bang
4. The apparent distances of the furthest objects in the "visible universe" corresponding to about 14 billion light years in distance

Now before all these observations, the de facto assumption was a Newtonian model, where gravity and momentum kept things in a constant near perfect eternal balance, with the universe having an unknown age. When hubble came up with the Big Bang, he was attempting to address the discrepancies that model had with reality.

Re:A few hundred extrasolar planets

[i kan reed]

Not as opposed to anything. I'm saying this is how science is supposed to work. We take new observations and use them to classify the properties of things according to the hypotheses that best predict the new information.

Re:A few hundred extrasolar planets

[i kan reed]

You're the second person to think I was complaining. What gives? Did you take the "I like how science works like that" as sarcasm?

Re:A few hundred extrasolar planets

[VanessaE]

Well for starters, the observable universe is something closer to 90 billion light years across, not 14 (or 28). The universe's *age* is about 13.7 billion years or thereabouts. You can thank the inflationary period after the Big Bang for that difference. It's the space itself that's expanding and *pushing* or *carrying* the matter with it.

Space can expand/move far faster than the speed of light - that universal speed limit simply doesn't apply to the fabric of spacetime itself. Same idea that makes warp drive so appealing.

Re:A few hundred extrasolar planets

[PvtVoid]

This is another thing that bothers me. If we can see stars as far away as the universe is old, then we (or the matter we are composed of) must be moving away from them at very close to the speed of light, since we were once very close to them.

Things as (almost) far away as the universe is old are moving away from us at (close to) the speed of light. Things farther away from us than the universe is old are moving away from us faster than the speed of light. This is perfectly consistent with General Relativity: it seem to contradict Special relativity, but it actually doesn't.

Re:A few hundred extrasolar planets

[PlusFiveTroll]

The problem is 'i kan reed' is a sarcastic asshole in all his conversations and not this one alone. Assuming he is being sarcastic is no great leap of interpretation as, from his own history, just about everything he says is sarcastic.

Re:A few hundred extrasolar planets

[ShanghaiBill]

You think the physics of planet formation in our galaxy was somehow magic or something?

The evolution of intelligent live requires far more than "planet formation". The more we learn about Earth's history, the more we realize how long the odds were. First you need a rocky planet in the habitable "goldilocks" zone. Those are common in our region of the galaxy, but are likely less common further out, where there is more hydrogen/helium and fewer heavy elements. Then you need liquid water. The early earth was too hot and small to hold on to water (it lost almost all it's neon, which has about the same molecular weight). So the water came later, from comet impacts. But if you have too many big gas giants, they will suck up all the comets, and you end up with a desert planet like Arrakis (but without either worms or molecular oxygen). Too few gas giants, and you get too many comet impacts, which form a global ocean hundreds of km deep, like Europa. A ocean that deep has no upwelling, so the nutrients sink to the bottom, where there is no energy other then volcanic vents. Even if you get the water level right, too many comet ELEs can wipe out species before intelligence evolves. To few ELEs, and life stagnates, as species evolve into narrow niches.

Re:A few hundred extrasolar planets

[K. S. Kyosuke]

Fortunately, Mother Nature had a metric fuckton of tries at her disposal. The only bad thing about the odds is that we won't be hearing of other such civilizations every two decades on Space CNN because the other successful tries will be too distant in time and/or space.

Need two data points

[gurps_npc]

to do any extrapolation. With just a single data point (humanity), you are just making wild guesses.

For all we now, dark matter (the most common form of matter), which we have never seen or studied, has variations as significant as normal matter, and therefore can support life, but only inside very radioactive areas, where they can feed.

Not to mention we really need to to take a look at a couple of the ice moons and see if life does well living on moon with a frozen surface and a hot core providing energy. That could very well be the most common form of life sustaining location in the universe, and it could very well survive in places where atmospheric planets like earth could not.

The very best we can do is make an estimate on where DNA based life forms may thrive on atmospheric planets..

How do we know life can't adapt to it?

[satuon]

Would the lethal radiation kill life in the deep ocean? It would need to kill ALL of life on that planet to make the planet inhospitable to life. Otherwise life would just adapt to it as yet another selection pressure.

Re:Like Niven's "At the Core"

[Anonymous Coward]

Niven's story is fine, but your conclusion isn't. If the massive wave of radiation is focused on a particular spot like Earth then the Earth is toast, but the rest is safe because the wave wasn't focused on it. If the massive wave of radiation is not focused on a particular spot, then its intensity decreases as 1/r^2 and everyone is safe.

Re:surface-life biased study?

[Bengie]

The average GRB lasts about 0.3 seconds and releases as much energy as if your took 1,000 Earth and turned all of the mass into pure energy. If you're anywhere near that, bad things will happen.