200 billion galaxies, 400 billion stars each...Are we All there is? Are we alone ? - Writers Forum

Gate · 04-07-2008, 02:22 AM

Are we Alone in this vast universe?

There must be trillions of planets orbiting stars.....for everything to happen just right .....the right distance from a star...magnetic protection....water..atmosphere....even with the odd at a million to one there should be thousands of life sustainable planets.....of course we've only been listening for about 85 years.....really listing for 50....enough time has past for civilizations to come and go ...where is the evidence or are WE it?

lets talk.

Swamp Thing · 04-07-2008, 06:56 PM

Yep, we are it. And we'll have roasted to a blackened marshmallow in 40 years according to Al Gore and other purveyors of carbon credits. The universe is doomed to live without rock n roll.

Modest Me · 04-07-2008, 07:04 PM

Hey, of course we are the only ones! If there was anything to be found, the government would have found it already. If the government knew about other life, they would have told us. *laughs to herself*

Malone · 04-07-2008, 07:06 PM

There was a thread on this a few months ago.

Non Serviam · 04-07-2008, 07:24 PM

Let's narrow that 400 billion stars per galaxy down a bit.

Astronomers keep telling us the Sun isn't an unusual star. But, they're lying--it's unusual all right.

It so happens that within a 20 light year radius of Sol, there are exactly 100 stars. Of them, 90 are less than a third as bright as our sun--probably too small and dim to have a reasonable-sized habitable zone, and one (Sirius) is too big--big enough to burn out all its fuel before life could possibly evolve. So that leaves 9: Alpha Centauri A, Alpha Centauri B, Tau Ceti, Epsilon Eridani, Procyon, Sigma Draconis, Eta Cassiopiea, Delta Pavonis and Beta Hydri.

Of those, Epsilon Eridani's too young. It's still surrounded by a planetary accretion disk. Even if any solid planets have formed yet, life hasn't had time to evolve. Procyon's got this extremely massive degenerate matter companion that'd sweep away planets in the habitable zone. So that leaves seven stars.

Taking that as representative, about seven percent of stars COULD have a planet of roughly the right age in the habitable zone. What proportion of this seven percent actually does? A third? Your guess is as good as mine--but for the sake of argument let's say this narrows it down to 2% of stars.

How many of those have a large moon, like Earth's? A large moon's useful for tides that wash oceanic life up onto land, and for maintaining a strong magnetic field (note that Mars had liquid water before its magnetic dynamo failed... there's some evidence that a decent magnetic field's necessary for a life-sustaining planet). What's the percentage? Say one planet in ten, for the sake of argument. So you've got 0.2% of stars.

Of those, how many have an atmosphere and oceans? And of those, on how many planets does life actually evolve? And when it does, how often does it progress to the multi-cellular stage? And then how often does it progress to plants and animals? And then how many of those progress to tool-using animals? And how many tool-using animals have language?

If it's one in ten for each of those questions--which it certainly isn't, but for the sake of argument--then we're at 0.00002% of stars that are within about 4 billion years of having an intelligent civilisation.

Which hypothetically gives us 80,000 stars in the Milky Way that could potentially harbour life.

But wait, it doesn't. Stars near us are what's called Population I stars, i.e. those made of the dust of other stars. But stars elsewhere in the galaxy are often Population II stars, which won't have so many elements heavier than helium, so may not be able to form life. So let's restrict it to the Population I stars and say that's half of them--40,000 stars in all.

Earth's existed for 4.6 billion years and life capable of getting off the planet's only just evolved. Now here's a scary question: How long, on average, does a civilisation last? How many of them go up in nuclear smoke or some kind of environmental holocaust within a thousand years of discovering nuclear power?

If the previous numbers are correct, and it's 4.6 billion years to evolve, and only a thousand year average lifespan once you've learned to get off-planet--then we're probably alone in the Milky Way.

That explanation terrifies me.

Malone · 04-07-2008, 07:36 PM

I've heard that same argument of possible life supporting planets used to the opposite ends, Serv. I think it just depends on the physicist/cosmologist/astronomer/mathematician you listen to.

Non Serviam · 04-07-2008, 07:41 PM

Oh, sure. I'm happy with my characterisation of the nearest 100 stars, but after that, the numbers are pure, unadulterated guesswork. You can use different assumptions and come out with figures like a thousand, or ten thousand, or a hundred thousand civilisations existing at once.

I'm just showing why the big numbers aren't necessarily a convincing argument in themselves. There are numbers of unknown (but large) size on the other side of the equation too, so the answer to "how many spacefaring civilisations in our galaxy?" could, for all we know, very well be "1".

Neo · 04-08-2008, 04:28 PM

It's statistically and intellectually impossible that Earth is the only planet with any life, intelligent or otherwise, in a universe tens of billions of light years across, tens of billions of years old.

Nah, there's plenty of life around - remember, life could exist in conditions we're not used to seeing - different kinds of life forming in different environments.

CroZ · 04-08-2008, 05:04 PM

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It's statistically and intellectually impossible that Earth is the only planet with any life, intelligent or otherwise, in a universe tens of billions of light years across, tens of billions of years old.

Nah, there's plenty of life around - remember, life could exist in conditions we're not used to seeing - different kinds of life forming in different environments.

The idea of intelligent life is pretty much squashed by the fact that we haven't picked up any of their signals. We often hear how these super alien beings can't pick ours up because we're so far away - travel time. But they rarely comment on how we should have by now picked up some of there's. Even if other races are extinct their signals should still be present in space, now more than ever because they'd have more time to travel. Since most planets appear to be much older than the Earth it would make sense any races present have had more time to develop.

As for lower life, well they were pretty sure they'd find traces of life on Mars but the planet turned out to be too salty. I read an article recently, I don't remember correctly so I might be wrong, stating the planet at no time bore water, therefore any form of life. In any case, that's a planet right on our doorstep, a planet we've studied and inspected up close. If their assumption turned out to be wrong on that then it seems naive to jump to that conclusion for planets millions of light years away. Alien research is based on wishful thinking.

Neo · 04-08-2008, 05:35 PM

So, CroZ, you're saying that life is impossible in this universe?

There's me thinking Earth had life.

Katastrof · 04-08-2008, 06:09 PM

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Originally Posted by CroZ

The idea of intelligent life is pretty much squashed by the fact that we haven't picked up any of their signals.

Did you know SETI has only been searching the night sky for about 37 years and it barely searches a quarter of the sky for electromagnetic signals? And that most of the signals it looks for are only radio signals? You expect to find intelligent life in only 34 years when the universe has existed for more then 14 billion years, when we are only searching a rain drop sized portion of the universe; can anyone even picture how big the Solar System is (not in kilometers, I mean actually picture all that vast nothingness), let alone the universe?

If anything the fact we haven't picked up signals from intelligent life means that we haven't been looking hard enough.

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I'm just showing why the big numbers aren't necessarily a convincing argument in themselves.

I disagree with you NS, because the big numbers are exactly why intelligent life is possible. There are more stars in the universe than there are grains of sand on the Earth; think about that for a second, that's a humongous number! To some estimates that's 5 x 10^21 stars in the universe! To think that the odds of intelligent life being 1 : 5 x 10^21 stars in over 14 billion years is ridiculous.

And it's even more preposterous thinking that Earth is the only model of life.
It is the only model we know of, but that doesn't mean it's the only model out there. If anything, scientific discoveries have proven that we don't know sh*t about anything. It was less than 50 years ago that we thought protons, neutrons and electrons were the smallest particles but then we discovered quarks! 100 years before that we didn't even believe there were protons and electrons. 300 years before that we didn't even realize that atoms existed! (well technically we did 2000 years ago but it wasn't very scientific...)

Nothing is impossible. Just not very probable.

You are on track though, with reason why we haven't met them yet.

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Earth's existed for 4.6 billion years and life capable of getting off the planet's only just evolved. Now here's a scary question: How long, on average, does a civilization last? How many of them go up in nuclear smoke or some kind of environmental holocaust within a thousand years of discovering nuclear power?

A very good question, and the reason I think we haven't met and probably won't (never say never) is because of the average life span of a civilization, the amount of time it spends broadcasting to outer space (before it develops technology that keeps most signals to itself), and when it self-destructs (or becomes a self-sustaining Dyson sphere).

I heard a good analogy once on a Discovery program. It said to picture all the civilizations of the universe as blinking lights on a humongous Christmas tree. Some lights stay on longer than others, some don't stay longer than a blink of the eye, but it's almost impossible for two lights to blink as close to each other so that both of those lights could see each other blink.

Basically the same conclusion that states intelligent life is abundant (because of the massive numbers) also states because of the massive numbers (distance, longevity of the civilization, placement) means that two intelligent lifeforms meeting is not.

CroZ · 04-08-2008, 07:02 PM

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Did you know SETI has only been searching the night sky for about 37 years and it barely searches a quarter of the sky for electromagnetic signals?

Yeah, I heard it on all those documentaries which also claim millions of planets are capable of supporting life, which Non already pointed out tend to be over simplified.

This is why I pointed out that aliens, at least the majority, would likely be around longer than humans. Whenever they existed, whether extinct or not, their signals would still be traveling, the older they are the more traveled they should be. It's not a question of pointing a gadget and tracking a tiny signal, the earth would more likely be basking in these signals, that includes a quarter of the night sky. Then if there were more than one race out there we would likely be succumbed by signals from every direction, every planet ever occupied should be emitting a signal along with every satellite or space station. We're still picking up natural signals from the far reaches of the universe.

Then there's the question of absolutely no activity on their part. Man began exploring space the moment they could, they even sent out a greeting satellite. Doesn't it make sense the aliens might themselves be curious? They'd surely send beacons past any borders they've reached, or utilize a more direct means of reaching other planets. We'd certainly notice these things before they even came close to our planet.

Either there's no intelligent life out there, or very very few.

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And that most of the signals it looks for are only radio signals? You expect to find intelligent life in only 34 years when the universe has existed for more then 14 billion years,

First, you seem to be assuming the aliens were immediately blasted with technology beyond are own. More likely they developed like us, meaning they'd have used something similar to radio signals, meaning it should be easier to spot those over anything else. Same for us.

Second, the big bang didn't just fire out planets, they took billions of years to form, so knock off a few billion from the number. Then it's safe to assume life didn't just sprout up so knock off another billion or two before primitive life might have formed. It narrows down the time frame.

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when we are only searching a rain drop sized portion of the universe; can anyone even picture how big the Solar System is (not in kilometers, I mean actually picture all that vast nothingness), let alone the universe?

From what I've heard they're pretty close to seeing the universe in its earliest form, with Hubble, so probably.

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If anything the fact we haven't picked up signals from intelligent life means that we haven't been looking hard enough.

We shouldn't even have to look. They'd already be fucking with our own equipment whether we like it or not.

A-L · 04-08-2008, 07:41 PM

I don't think that we are the only life in the entire galaxy. What I do think though is that we are looking for life in ways and laws that seem to apply on our planet. Whose to say that all life forms the exact same on different planets? A planet being devoid of the necessary components for life on earth does not mean that it couldn't support life of a different kind. Laws and theories sometimes bend and I'm pretty sure that somewhere across the vastness of the universe there is life that is utterly different in its formation and function.

MisterVanOsten · 04-08-2008, 09:55 PM

How many planets are capable of supporting life? Why, the answer is right here:

N=N*FpNeFlFiFcFl - The Drake equation. Supposedly, if you plug all the information about a particular galaxy into the corresponding variables, you will have the number of communicating civilizations in that galaxy. This equation was developed in 1961, so I don't know how accurate it is, but here is a website that can tell you more: SETI: The Drake Equation

A Vaulter's Insanity · 04-08-2008, 10:33 PM

Habitable zone is most likely a lot larger than most people think. If life needs water, then the habitable zone could be below freezing or hotter than steaming. If it doesnt need water, then it could be as close to a star as mercury (or closer) or as far as Pluto (or father). The planet doesnt need oxygen, cause there is life on our own planet that doesnt need oxygen. Every argument that tells you how perfect everything has to be is probably blown out of proportion. Life evolves, it changes, it adapts to its surroundings. We have no idea how life was originally formed (unless youre religious) and all our predictions could be way off. If life can be formed, then it probably will be. If life is, then it will probably evolve.

But do I believe there's intelligent life as we know it? I lean one way or another depending on how I feel that day. Life is as we know it. And were very misinformed to be making guesses about life that we dont know about. there could be life that has 20 senses and is only made of gases and can learn faster than us but doesnt need too because everything on the planet just floats around in a happy bliss. Life is as we know it. And we dont know much