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Milky Way Star Births May Have Influenced Life
eldavojohn writes "Space.com has an interesting article that speculates that the period when our galaxy was giving birth to stars resulted in huge fluctuations and impact on earth. From the article, 'Some 2.4 billion years ago when the Milky Way started upping its star production, cosmic rays — high-speed atomic particles — started pouring onto our planet, causing instability within the living. Populations of bacteria and algae repeatedly soared and crashed in the oceans.' Causes one to wonder what the probability for life arising on a planet is given that our own seemed to be in a very unique situation on many different counts."
Even if the chances were one in a billion or one in a trillion, the sheer number of stars and planetary systems in the galaxy (and indeed the universe) make it entirely unlikely that there *isn't* life out there somewhere. Humans seem to want to be perceived as being special on both an individual and a collective level. We don't really want to accept being common or normal or average. There is life out there somewhere. We'll never find it because of the distances involved, but I am convinced it's there. I think we beat huge odds to get here, but there are still huge numbers of other civilizations that beat similar odds.
2.4 billion years ago, cosmic rays travelled through space to create this first post.
In general, any period of time where there is massive stress on a population would likely see rapid evolutionary changes. Whether it's volcanos, or asteroids hitting the planets, an ice age, or interstellar radiation, the effect is basically the same - an initial decimation of existing populations with amazing biodiversification thereafter.
Huh? Don't mind me, I'm just the new guy.
To borrow a theme from Carl Sagan.
:P
Estimations are that there are 100 Billion stars in our galaxy. Thats:
100,000,000,000 -- Let's say 1 in ten of those are in a good region of the galaxy (not a bunch of cataclysmic crap going on)
Thats: 10,000,000,000 -- Let's say 1 in ten of those have planets.
Thats: 1,000,000,000 -- Let's say 1 in ten of those have a planet in the stars habitable zone
Thats: 100,000,000 -- Lets say 1 in ten of those have adequate amounts of water
Thats: 10,000,000 -- Lets say on 1 in ten of those simple life arises.
Thats: 1,000,000 -- Lets say on 1 in ten of those complex life develops.
Thats: 100,000 -- Lets say on 1 in ten of those intelligent life develops.
Thats: 10,000 -- Lets say on 1 in ten of those advanced civilization pops up.
Thats: 1000
10,000,000 planets that foster life, and 1000 advanced civilizations.
I think the chances are pretty good.
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Let's say 1 in 10 of those decide to start colonizing other star systems with generational ships. Where are they?
Ben Hocking
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'Some 2.4 billion years ago when the Milky Way started upping its star production, cosmic rays -- high-speed atomic particles -- started pouring onto our planet [...]' Causes one to wonder what the probability for life arising on a planet is given that our own seemed to be in a very unique situation on many different counts."
While Earth does seem to be unique amongst the hundred or so planets that we're aware of, the above circumstance is not one of the reasons. Those cosmic rays would have been pouring onto every planet in the galaxy, or at least this corner of it. If that cosmic ray flux did have an effect on jump starting the primitive life that was around at the time, it may have done so on tens of thousands of planets.
It may also have wiped out the local equivalent of the dinosaurs - or even intelligent species - on some other planets.
-- Alastair
All these stars were a long, long way away.
The amount of radiation (any sort) falling on a body decreases in an inverse square manner, so I doubt that even in the maddest periods of star formation there would have been more than a tiny effect on our atmosphere, especially compared with the effects of a cosmic ray emmitter only 8 light-minutes away that may also have been fluctuating wildly.
In short, I'm sceptical.
One swallow does not a fellatrix make
Read the link in my GP post about the Fermi Paradox. It explains that once a civilization develops that starts colonizing other worlds, it will tend to generate two (or more) other inhabited planets. This will then lead to 4, 8, 16, until after 40 such doublings you have over a trillion inhabited planets (i.e., about 10 for every star in the Milky Way). Obviously there will be limiting factors (such as the number of inhabitable planets), but you'd think that eventually (i.e., in less than a few million years), they'd find Earth - we wouldn't need to find them.
Ben Hocking
Need a professional organizer?
The probability of life appearing on a planet may be high, and our planet's situation may not be as unique as you think. I study Planetary Science at the Open University (UK) and the fact that they decided to couple lessons about the search for life in the, primarily geology-themed, planetology course has to say a lot about what scientists think of the Rare Earth Hypothesis.
It is, however, natural that some people think that Earth is unique, as it is the only living planet we know of. Sure, your first lemonade was unique, your first PC was unique, and your first GNU/Linux distro was also unique.
I wouldn't call stop using electromagnetic waves as killing yourself off. Besides, even on earth, our radio transmissions becomes more and more difficult to detect. Our transmissions look more and more like noise, heavily compressed digital data. Instead of AM and FM, we increasingly use more obscure technologies, even multiband. And we use lower power in our transmissions. Add a few thousand years to that, and I doubt we would be able to detect ourselves.
Also, radio is a pretty recent invention. It's not something humanity has depended upon for millenia. If we are still using radio in 5000 years, you might have a point. As of now, I don't think it's completely unthinkable that we will invent something better. Perhaps as a result of finally finding a grand unified theory in physics, or something else way longer down the road. Remember, the perspectives we are talking about in cosmic scale is billions of years. Here we keep complaining that progress in AI, fusion, string theory, etc is slow because nothing has happened in 50 years.
That, at least, is for sure!
The worst of the fundies take a very old document from a time when metaphor was often used and interpret it both very literally AND very selectively. (eg gays are bad but wearing blended clothes is ok and they don't keep Kosher*. That's the same old testament! ) And they choose to very literally interpret the English translation, no matter what the original probably said. In a country which is really not that literate I can see how this happens - religion is about your pastor, not about the book.
But not everyone who's religious is like that. It's perfectly reasonable to think that G-d guided each step of evolution - evolution isn't incompatible with G-d at all. But I think this doesn't give your G-d enough credit...
Which do you think shows more omnipotence: Building a car that G-d has to tuneup every 100 miles, or building a car that drives forever and constantly improves itself on the fly to be better for existing road conditions.
Evolution does not logically require a god. But to me the wonderful elegance of evolution - and indeed of most science once humankind actually understands the topic fairly well - is closer to be proof OF G-d than a refutation of him/her.
My personal feeling is that if someone can't understand how I can have this position (even if they disagree), they need to take more math and science classes.
Computers are really built on just a couple SIMPLE elements - transitors. But millions of these SAME elements working together in a particular way gives us the computer I'm typing this on, Google, and Wikipedia. There is a wonderful elegance to this extreme complexity being built from the extreme simplicity of the evolutionary process.
Alchemy was really hard. With chemistry we can do much more... and we realize that all things we're familiar with are made up only of protons, neutrons and electrons. (and those of quarks - and yes there are less-common particles and radiation)
When you get down to basics, there's only a very few times numbers we need that aren't integers... All around, it's extremely elegant.
*and Kosher food is often healthier than "normal" food, in the same general way that Organic is - there are rules about icky things you aren't allowed to do prepping them.
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Hard radiation to generate mutations can't be a limiting factor because it's not in short supply in the universe. Without Earth's magnetic blanket, we'd be getting so much, even without major galactic star formation, the trick would be staying alive rather than generating enough mutations to do anything interesting.
The probability of life arising is much more difficult to pin down. Right now, we have one data point: Earth. Kind of hard to extrapolate any sort of line from that. Invented probabilities, like those in the Drake equation or Sagan's discussions, may be plausible, but since they're not factual we can argue about them forever.
What we do know is that life arose on Earth very quickly after the initial heavy bombardment slowed down. Very quickly means a few hundred million years. That's fast enough to mean that life probably arose several times, each time getting wiped out in a new wave of bombardments, until the meteor strikes finally weren't big enough to liquefy the whole surface of Earth. Or until life was widespread enough that devastating half the Earth wasn't enough to kill it. Here again, we have no proof that repeated chemical evolution of life happened, but the speed with which it did happen, at least once, implies that it's not a particularly iffy process.
The lack of a second data point is why solar system exploration is so hugely important. Mars had a few hundred million years with liquid water. If there is evidence of fossil bacteria from that time, it'll mean there is life everywhere in the universe where there is water. I can't imagine anything more significant than that. And if exploration of, say, Europa, also turns up bacteria, well, then it'll be all over except the shouting. NASA, ESA, Japan, _everybody_ needs to hurry up and send those critical missions out there so that we have our answers, and this forum can sink it's teeth into them!