Astrophysicists Identify the Habitable Regions of the Entire Universe 80
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."
A few hundred extrasolar planets (Score:5, Interesting)
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.
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As opposed to, what, assuming that our galaxy is unique and special and doesn't follow the same rules as the other ones?
You think the physics of planet formation in our galaxy was somehow magic or something?
Use your big-boy words, because you sound like a gibbering monkey. I can't even tell WTF you're on about.
Re:A few hundred extrasolar planets (Score:4)
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.
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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 abou
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As opposed to, what, assuming that our galaxy is unique and special and doesn't follow the same rules as the other ones?
Well, you can only extrapolate from what you have, so it is a useful exercise, but there is no reason that the rules apply the same everywhere. Nobody really understands what kinds of fields might exist on a large scale across the cosmos so it may very well be that there are things that behave differently elsewhere.
It isn't about our galaxy being "special" per se, so much as the anthropic principle. There may very well be many galaxies in the exact same situation as ours, but that doesn't mean that all ga
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I see, so you're dislike of a theory somehow should be fed into whether that theory is legitimate or not.
Every piece of evidence gathered over the last century shows the universe is expanding, and that it was once much hotter and denser. The evidence for Big Bang cosmology and inflation are overwhelming, whether that pleases you or not.
Re:A few hundred extrasolar planets (Score:5, Informative)
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.
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What is the difference between space expanding such that the distance between them increases by 14 billion light years in 14 bil
Re:A few hundred extrasolar planets (Score:4, Informative)
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.
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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.
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If the space is expanding, I'd expect the objects to accelerate in time, and I'm not even sure how the speed of expansion changed over time, but I'm quite certain that merely dividing the current distance of two objects by the age of the Universe doesn't make much sense.
Well, relative to each other everything seems to be accelerating apart. Of course, that is a recent result - until recently the universe seemed to be nearly flat - that is the expansion of the earth was asymptotically slowing towards a static universe (which it would never actually reach).
I'm not an expert in such things, but there are a bunch of factors involved with relativistic motion. The relative passage of time slows, light becomes red-shifted (to the extent that an event that was incomprehensibly h
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I'm not sure if you're being sarcastic, but I really don't like how they do this extrapolation stuff. Like the universe is currently expanding, and based on the current rate of expansion (or the rate of change of that expansion) we assume it has always been expanding and that 14 billion years ago everything was crammed into something the size of a golf ball. I'm not anti-science, but that seems to be making a pretty big leap.
This is mostly because you apparently don't understand the theory (or the data) very accurately, which is fine. But to take a layman's understanding of something and concluded that "all teh scientists are idiots" is really, really not a good idea.
The evidence that cosmological expansion occurred in the distant past, not just today, is compelling, and direct. We can actually see light that has been traveling unimpeded since the universe was only 300,000 years old, which means that we can direct
millions in a few decades (Score:2)
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Since the universe, in every direction we look, behaves by the same physical laws, it isn't an unreasonable extrapolation at all. I'm not actually sure what you're complaining about.
Oh, I get it, you probably don't like science. All those really smart men and women, so much more accomplished than some blowhard on /.
Well, your lack of credibility and accomplishment is not science's problem.
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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?
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To be fair, your comment did have a pretty strong sarcastic tone to it. Maybe it wasn't intentional, but it was there.
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I think I see it now. Grandiosity as interchangeable with sarcastic hyperbole. Interesting.
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No, they understand & appreciate science - it's the very poorly worded message that the OP posted that many here are having problems understanding.
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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.
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Oh sure, everything I say is sarcastic. That's totally believable.
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It may have been unintentionally present, but it was there. The OP has already recognized his mistake and moved on. You should as well.
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Yeah, I take those studies with a huge grain of salt.
Not too long ago, there was a scientific consensus on conditions required for life. Deep seas (e.g. hydrothermal vents) were far far away from the accepted habitable regions on earth.
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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.
Of course, in the entire history of the human race, we've never once actually confirmed or refuted a single predictions if this nature. This is where "faith" comes in.
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Bullshit. People predicted that there were planets outside our solar system, and some contested that it was an oddity.
No evidence for thousands of years, then just over a decade ago, BOOM, demonstrated. You're just being intellectually lazy, here.
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They can only identify the known observable universe. However, it is unlikely that they have identified the habitable zone for the entire universe. It would be near impossible for them to identify the habitable zone for our galaxy. This is because we have no idea what is habitable because we only know about our life. Maybe that should say the like-human habitable zone of any given galaxy rather than the habitable zone of the universe.
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Sorry, no (Score:1)
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Actually, there's some sense in your statement. If you look at our world today, the biggest threat to life on this planet is not gamma rays. The biggest threat to life on this planet . . . is other life on this planet. Most of that is motivated by these "ancient superstitions".
The cruel irony is, that Islam, Christianity and the Judaism are all based on the same Jewish Fairy Tales. And despite that it seems that Muslims are hell-bent on killing everyone who isn't a Muslim. This latest Islamic State cr
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Which was all ripped from from the Babylonians, Sumerians, and Assyrians.
They just keep re-hashing the same old myths and acting like they've come up with something new.
It's all based on the same creation myth, even if they won't recognize it.
Everything thereafter is just editorializing by humans, and relying on "evidence" which would get you a psychiatric evaluation these days because they're little mo
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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.
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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 [amazon.com] ). 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?
I would find it very hard to believe radiation of such magnitude could be generated from a core and sterilize the galaxy on its way out. But then again, I'm not an Astrophysicist :)
You would also like to read Niven's "Protector" if you haven't, and how sentient life actually evolved in a radiated home world near the core.
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If the core has a lot of young, hot stars then it could certainly sterilize a galaxy, especially a small one (I haven't done the calculations myself, but I suspect they would back me up if I did do them).
Our galaxy is middle aged and very large, so we are probably not in so much danger out here in the galactic suburbs.
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Read up on active galaxies, eg http://en.wikipedia.org/wiki/A... [wikipedia.org].
Need two data points (Score:3)
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..
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Agreed. It's awesome how science is getting a better and better understanding of how much of the universe is hospitable to us-like life. But it's always mentally-painful when stories like this make loudly-screaming-assumptions that we are a typical, or exclusive, model of what life in the universe looks like. The most trivial problem with the current story is that undersea or underground us-like life won't be much bothered of the atmosphere gets nuked with radiation. Stretching things a bit, we have no ide
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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.
Actually, we're pretty sure dark matter is relatively smooth in its distribution and does not form anything even remotely equivalent to stars and planets (we'd see the gravitational lensing if it did). Nor can we figure out any way it could self-interact in a way that would sustain imperfectly replicating objects but not end up in clumps that eventually form large agglomerations.
This is not to say that such things are impossible--the fact that we can't imagine something is not evidence for its non-existence
How do we know life can't adapt to it? (Score:3)
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.
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But would life living comfortably in the subsurface ocean of a Europa be affected? I'd expect not.
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To get a sense of the energies involved: if you're a light-year way from a supernova, the neutrinos will kill you, even though they barely interact with matter at all. One light year is pretty close, but the gamma ray flux is comparable to the neutrino flux and forty orders of magnitude more deadly, so no, deep ocean life even at great distances from the exploding star will be boiled rather than fried, but it would still be dead.
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To get a sense of the energies involved: if you're a light-year way from a supernova, the neutrinos will kill you, even though they barely interact with matter at all.
Complete and utter bullshit. You are pulling numbers out of your ass. I give you the truth [xkcd.com]. I stopped reading your post after that sentence.
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That. Is. Fucking. Awesome. I'll now be stuck reading through the archives on that domain for a while...didn't even know it existed after all these years reading xkcd!
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The numbers you assign here do not match reality, since if neutrinos from a supernova can kill you at 1ly, and gammas from same are 40 orders of magnitude more deadly, then a single supernova would sterilize the
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They have ... (Score:2)
Visiting galactic cores still important! (Score:2)
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.)
Impressive! (Score:2)
Partial answer to Fermi's paradox? (Score:2)
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 t
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We're probably the first sentient beings to evolve because it doesn't make sense for God to incarnate himself as Christ here on Earth. If sentient beings exist on other planets, alien God incarnates (alien Christs) have to die multiple times to save the entire universe.
GRB's necessary for advanced life, perhaps? (Score:2)
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.
Good News! (Score:2)
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The most realistic answer is that space is bigger than you imagine, nobody knows we're here, and the energy required for long distance space travel never becomes practical or politically acceptable on a large scale. There's really no reason to expect aliens to continue spending their resources on expansion unless they're Borg.