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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."
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.
This isn't science's domain, as long as it has anything to do with origins. For that. we need ancient superstitions.
Tic-Tac-Toe, Global Thermonuclear War, and relationships all have the same winning move.
Like many here, I'm sure, I first considered the possibility that the galactic core was inhospitable to life when I read Larry Niven's 1968 short story "At the Core" (collected with his other "Beowulf Shaeffer" stories in Crashlander ). In his science-fiction tale, Niven had an astronaut visiting the core and witnessing the wash of radiation from so many supernovas placed so close together.
Niven's story, however, ended with the astronaut coming back and warning that this massive wave of radiation would be moving towards Earth at the speed of light. If that were true, and even the edges of galaxies were not safe in the end, then every galaxy would be ultimately hostile to life, not just in their cores. Is this the case, or did Niven get it wrong?
Statistical extrapolation say at least half of the systems have them. We can only detect the one percent of edge-on systems with transit method or the fat-fast ones with doppler. But we've barely started to look at the systems within a couple thousand light years. There are millions of starts within this distance.
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..
excitingthingstodo.blogspot.com
We already know that life takes all forms, including the discovery of some that eat radiation.
These predictions and the people making them serve to provide an answer to a question that they humanity is wholly unqualified to answer. We don't even have anecdotal evidence about extraterrestrial life, let alone knowledge of anything outside of the Moon and Mars where nothing on the scale of normal discussion lives.
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.
Life can evolve just fine. These gamma-ray bursts don't affect deep-sea vent life.
Have gnu, will travel.
Now that we have a 3D printer in Low Earth Orbit, clearly we'll be able to colonize the universe.
That's where you find the Wisdom Chits necessary to advance your civilization.
(Wow . . . no hit on the correct reference ten pages into a Google search.)
This whole mapping is based on the idea that life will be very similar to ours. This is a questionable premise, I think.
I read a great hypothetical article in ACM a few years ago that had me chuckling. It was called: "Fermi's Paradox and the End of the Universe" by Geoffrey Landis.
Go to page 115 of http://issuu.com/diriangem_bravo/docs/communications2012_10
The entire universe is not observable, yet they managed to identify all the habitable zones in the entire universe. Very impressive.
From the abstract: "life as it exists on Earth could not take place at z>0.5". I take this to mean (since I'm not a professional astronomer I am guessing that the variable "z" represents redshift) that life couldn't get started in the earl(ier) universe because the galaxies were closer together/with more gamma ray bursters etc.
So a partial answer to Fermi's paradox (where are they?) is that we are one of the "first" to evolve into sentient beings because for "most" of the period before life evolved on the earth the whole universe was mostly uninhabitable. Of course I put "first" and "most" in quotation marks because we're talking about billions of years here; maybe the universe became reasonably habitable "only" a billion years before life arose on planet earth; that's still a lot of time! That's why I say this might be a "Partial" answer to Fermi's paradox, there would still be time for some civilizations to arise way before us. Just not as many and perhaps no really ancient multi-billion year old civilizations.
On the other hand, it might very well be that without galactic ray radiation shaking up the DNA mix every now and then we'd all still be pond scum right now.
This is good news people as it is a mark in favor of the only optimisic answer I can think of to the Fermi paradox - i.e. life is rare and could only have formed fairly recently- the other answers are ugly and imply our imment extinction.... cheer up people!