Aliens: Do They Exist?

[Sava]

If the universe is infinite, then there are an infinite amount of sentient life-forms spread throughout the cosmos. It's just a question of how far away they are from us.

Do I think aliens have come to earth? No...

[Az]

IMO, The odds are very good. I think there is life in at least a dosen other places in our Galaxy alone, and maybe highly evolved life in 2 or three places. However, I am being conservative, and it actually can be much more.

Lets see. there are a hundred billion stars in the solar system=10^11.
Let's say that half of them are too close to the center of the galaxy, in high concentrations of stars too bright for life to exist. that leaves us with 5*10^10.
Lets say that one in a hundred stars has planets: 5*10^9.
a Small planet relatively close to the sun: 5*10^6 ( one in a thousand, a very unforgiving fraction., considering the fact that our sun alone has 4 rocky planets close to the sun)

a small planet that has a relatively large moon: we have two examples of this in our solar system, Earth and pluto. This gives us an approximate 1 in 5. yet, what are the chances of having a large moon circling a small planet close to the solar system.
I think that one in 100 is a fair estimate. we have 5*10^4.

lots of water: say... one in 20: 2.5*10^3.
A suitable atmosphere: one in 10? it gives us 250.

Where am I wrong with my guessing math?

considering the fact that we have hundreds of billions of galaxies, I would say that the chance that we are alone are well, almost nonexistant.

[Starchild]

Azazel actually posted a simplified version of what is known as the Drake Equation. You take the number of stars in the galaxy and then multiple by the percentages that would have planets, suitable conditions, life, intelligent life, radio broadcasting life, and how long those broadcasting civlisations would survive for.

An interactive Drake Equation can be found here: http://www.activemind.com/Mysterious..._equation.html

You have to set the numbers extremely low to get just one civilisation in the galaxy.

Of course, we may be totally wrong about what shape an advanced alien society would take. Something of particular interest for me is the phenomenom known as the Singularity (the Spike, the Techno-Rapture, etc). If current trends can be sustained at their current rates of increase, then stuff like computing power, nanotechnology, life span, etc all accelerate upwards dramatically over the next 50 years to form a spike which prevents us from predicting what lies on the other side. Of course, this may all be number plotting with no basis in reality. However, if it holds out, it stands to reason that other races have had their own techno-raptures in the past. A society on the other side of the singularity would be so technologically advanced we would be unable to know it in any meaningful way. They could be so minaturised from nanotech, so energy hungry they drain their sun, and so efficient that they scramble their broadcasts across multiple frequencies that, to us, they would appear as nothing but white noise and low level background radiation.

We could be staring at a million year old society at never realise it until they bother to take the time and energy to broadcast to us in a way we can understand (ie, on one frequency that we listen to, like the hydrogen band).

[Docfeelgood]

Whenever the topic of aliens comes up I find it intresting.

What I find intresting is that so many people can open there eyes to the fact that there could be life out there but close there eyes to the life that IS here.


THINK!

[Odin]

Yes, but none have visited Earth. This is based on the "Drake Equation":


there are 200,000,000,000 stars in the Milky Way Galaxy

10% of stars (20,000,000,000) are of the right type. (yellow or orange main sequence stars)

10% of the yellow and orange stars (2,000,000,000) have planets.

10% of solar systems (200,000,000) have terrestrial planets. (most of the rest are messed up with gas giant planets incrediblly close to its star, or have highly eliptical orbits)

10% of terrestrial planets (20,000,000) are at the right distance from it's star.

10% of planets in the right orbit (2,000,0000) have liquid water.

10% of oceanic planets (200,000) have life.

10% of living planets (20,000) will have large, multicellular organisms.

10% of planets with higher life forms (2,000) have intellegent life.

So, there are about 2,000 sentient species in the Galaxy.

[Az]

This is very much correct, Starchild, but such a singularity ignores the fact that a great ecological collapse is predicted for around the same time. The decline of the world population that large, that only one tenth of the current population will survive.

You can see plenty of research that predicts that, unless we stop our reliance on fossil fuels.

[Ben Kenobi]

lots of water: say... one in 20: 2.5*10^3.

How do you get water in the first place? In such large amounts as we have here in Earth? I doubt one out of every 20 planets somewhat earthlike conditions will have the water. You probably need a more pessimistic function.

Stuff you left out:
Presence of a substantial magnetic field.
Axis tip for seasons.
A decent rotation period.

a Small planet relatively close to the sun:

A planet of roughly Earth size. Mercury cannot hold onto an atmosphere, nor can Mars.

You also need to exclude close binary stars, which exist outside of the centre of the galaxy.

there are a hundred billion stars in the solar system

That's some solar system.

[Az]

I meant galaxy.

obiwan, there is plenty of place in my fractions to place that category into.

[Starchild]

Originally posted by Azazel
This is very much correct, Starchild, but such a singularity ignores the fact that a great ecological collapse is predicted for around the same time. The decline of the world population that large, that only one tenth of the current population will survive.

You can see plenty of research that predicts that, unless we stop our reliance on fossil fuels.

Oh yeah, planetary-wide ecological collapse would be a major hiccup. The technologies responsible for that collapse are all Industrial Revolution hangers-on that can be phased out by the next generation tech leading up to the Singularity. I've been reading the Viridian Manifesto lately and it's right: As a civilisation, we're addicted to fossil fuels and need to wean ourselves off of them. We've got the science to do so, we just need to get the cultural shift, the artistic spirit to do so.

The current generation of Euroleaders isn't exactly inspiring for their attempts to shift to a hydrogen economy but it's a lot better than some first world leaders *cough* who are actually so deeply a part of the hydrocarbon addiction that they're stepping backwards.

[Odin]

Originally posted by Azazel
You can see plenty of research that predicts that, unless we stop our reliance on fossil fuels.

Bush *cough* Oil Industry *cough*

SEND IN THE HYBRIDS! (Cars that is)

[Az]

Hybrids? bah. Fuel Cell research is doing very well, I heard.

But we need a new energy resource. If we only wisen up and make the necessary leap to tap into one of the available nuclear power resources, we'll be able to power up the plants that would create fuel for the cars.

Global warming is one thing. The other thing is that a country can basically have a metal industry without natural resources. It can simply mine for ore in the landfills and such. Tons upon tons of Fe, Al, Cu, and other atoms lie around. All we need to do is process them efficiently. I worked for a shipping company once, and here I read on one of the bills of lading, that the export cargo is Aluminum. Why isn't it utilized as well as the regular mining? It's not that all the metal dissapears when it's used. It's dumped. And I will not be surprised if processing it would be actually easier than processing ore.

[Odin]

Originally posted by Azazel
Hybrids? bah. Fuel Cell research is doing very well, I heard.

But we need a new energy resource. If we only wisen up and make the necessary leap to tap into one of the available nuclear power resources, we'll be able to power up the plants that would create fuel for the cars.

Global warming is one thing. The other thing is that a country can basically have a metal industry without natural resources. It can simply mine for ore in the landfills and such. Tons upon tons of Fe, Al, Cu, and other atoms lie around. All we need to do is process them efficiently. I worked for a shipping company once, and here I read on one of the bills of lading, that the export cargo is Aluminum. Why isn't it utilized as well as the regular mining? It's not that all the metal dissapears when it's used. It's dumped. And I will not be surprised if processing it would be actually easier than processing ore.

If we tried that the garbage disposal lobby in Washington (or Jerusalem, or London, or Berlin or Paris...) would get in the way

[ravagon]

Originally posted by FrustratedPoet
Exactly Boris. Even if the probablity of other sentient life living around any given Star is a Thousand-Billion to One then there should be some out there.

Calculations made some time ago regarding the possibility/probability of the number of worlds capable of supporting "Earth-like" life in this galaxy yielded a lower limit of 10 000 and an upper limit in the millions IIRC.
This included Stellar class, distance from the primary, planetary mass, magnetic field and presence of both atmosphere and water.
Much of this is, of course, guesswork, and the existence of native life at any level, let alone sentient intelligent life wasn't covered - still, with that many possibilities it seems astronomically improbable that there isn't any "Earth-like" sentient life out there, without even allowing for the possibiliies of "other" lifeforms.

Note 1 : The term "Earth-like" leaves quite a bit of room for interpretation.

Note 2 : Sentient life elsewhere in the universe has pretty much the same probability of being highly irritating as does life here on Earth.

[Jaguar]

I think we're one of the frontrunners technologically in our area. After all, we haven't been contacted yet, and we can put stuff in space, but not contact anyone else. That suggests that the other species in our area are either in the same position or farther back technologically. I don't doubt that other intelligent life is out there somewhere.

[Boris Godunov]

Originally posted by obiwan18


Boris, some Christians think that there are other lifeforms, some don't.

I'm well aware of that, what I was wondering was why some Christians don't. AFAIK, there is no Biblical injunction against alien species, and as I mentioned, one part even refers to God's "other flocks." Considering the vastness of the universe is not in dispute, I wonder why some Christians would choose to believe this, except out of some sort of earth-centrism.

I used to weigh on the pro-alien side until I looked at the evolutionary arguments, the possibility of life forming from scratch, given the amount of time we estimate for the universe.

The odds are not good, and we still don't know what it takes to make life from scratch, so it seems reasonable to presume that there will be additional conditions for life to form.

Not sure where you're getting this from (my hunch is Creationist sources ), but we really don't know if the odds are "not good" or not. In fact, it has been theorized that the odds of ambiogenesis on an earth-like world are close to 1. And then we don't know if sentient life needs an earth-like world or not--it may very well be possible under completely different conditions.

At any rate, I don't see what any of that has to do with a Christian not believing in alien life forms. After all, an omnipotent God can presumably create life when and where it wishes. It it wanted, every planet in the entire universe could be populated entirely with magical unicorns.

Throw God into the mix, and "odds" don't matter.

Wasteful?
Maybe God likes the universe neat and tidy.

What's so neat and tidy about 125 billion galaxies full of all kinds of stars, planets, gas clouds, etc., all rotating around, and yet no lifeforms to enjoy the bulk of it?