Aliens are real???

[TheEconomist]

Wasn't a joke. You said he would never learn. Other than your nationality and sensitivity towards the subject, I was wondering what you were going on about. Yes, it was an awful joke, yes it was stupid and pointless, but that's it.

[Arkalis]

*sighs*

These kids will never learn...

The above post is likely a joke. Lighten up.

[Blazur]

http://www.ibtimes.com/articles/1328...s-ufo-hoax.htm

I'm sure aliens exist somewhere, but I highly doubt they've ever visited this planet.

[DemolitionSquid]

The general sane consensus is that with an estimated 400 billion stars in this galaxy alone, at least half of them probably have planets. With at least 1/10th of those planets them having liquid water in substantial quantities, there could easily be up to 20 billion planets with life on them. Its more likely only 1/10th of those do, though, so 2 billion. And chances are from that, maybe 100 million with sentient life. Given how close we've come to nuclear war, I'd say a safe estimate of the number of sentient species who survive their nuclear age and could achieve space travel in this galaxy alone is 20 million. Which is damn impressive and completely reasonable.

The question of whether efficient, short-term space travel between one star and the next is even possible, however, is an entirely different question based on our own current and limited understanding of the universe and physics.

[Gradius]

Not regarding that many of its variables are totally arbitrary and that the margin of error is beyond reasonable, most estimates of the Drake equation are too high IMO. Modern estimates are much lower than Drake's. A planet would need a large gas giant in Jupiter's position to fling asteroids away from our area of space. It would also need the disproportionately large moon that Earth has, whose tidal forces played a role in the evolution of life i.e. stabilizing Earth's axis wobble to prevent sharp climate changes, and perhaps even in activating the hydrothermal vents where life might have began. There's even a theory that its tidal forces are required to pull apart the double helix strands in the early DNA that formed in the primordial soup. Also, the Drake equation takes no account of the age of the galaxy. Perhaps millions of civilizations did arise, but it also takes billions of years for life to arise, and at different points in time too, so this window is far smaller than most people realize. In our galaxy, I'd be happy if right now, there were, say, 500 intelligent civilizations.

[Hellgrinder]

That's not entirely true either. Life could arise on an Earth-sized moon orbiting a Jupiter-sized gas giant that orbits its star in the area where Earth is, like in the Mu Arae system (There's a gas giant that fits that description there. Not sure of any moons though). Or, it could arise on a Europa-like moon.

Or, it could arise in a Titan-like environment, as recent studies have shown that there's less hydrogen on Titan's surface than there should be, suggesting that something is consuming it. According to models of what life on Titan would be like, using hydrogen where we use oxygen, acetylene in place of glucose, and methane in place of water. Throw in the fact that the amount of missing hydrogen fits the predictions for what it would be if there was life on Titan, and you've got evidence for life there, suggesting that you don't need an Earth-like environment to have life.

[Gradius]

That's not entirely true either. Life could arise on an Earth-sized moon orbiting a Jupiter-sized gas giant that orbits its star in the area where Earth is, like in the Mu Arae system (There's a gas giant that fits that description there. Not sure of any moons though). Or, it could arise on a Europa-like moon.

Or, it could arise in a Titan-like environment, as recent studies have shown that there's less hydrogen on Titan's surface than there should be, suggesting that something is consuming it. According to models of what life on Titan would be like, using hydrogen where we use oxygen, acetylene in place of glucose, and methane in place of water. Throw in the fact that the amount of missing hydrogen fits the predictions for what it would be if there was life on Titan, and you've got evidence for life there, suggesting that you don't need an Earth-like environment to have life.

Well I did in fact say I was talking about planets, not moons, but the point is, life is more likely to arise on a planet/moon that has significant tidal forces acting on it. Titan has Saturn, so it's got that going for it, but I'm sure it has a few things against it. Like the temperature. Or lack of magnetic field. In any case, I don't think some missing hydrogen is very good evidence for life. Need moar info. :P

[Hellgrinder]

Well, at that distance from the sun, a magnetic field wouldn't really be that necessary to hold on to an atmosphere. At Earth's distance from the sun, yes. But the solar wind out at Saturn is so weak that Titan doesn't need one. Either that, or it's protected by Saturn's magnetic field.

[TheEconomist]

The general sane consensus is that with an estimated 400 billion stars in this galaxy alone, at least half of them probably have planets. With at least 1/10th of those planets them having liquid water in substantial quantities, there could easily be up to 20 billion planets with life on them. Its more likely only 1/10th of those do, though, so 2 billion. And chances are from that, maybe 100 million with sentient life. Given how close we've come to nuclear war, I'd say a safe estimate of the number of sentient species who survive their nuclear age and could achieve space travel in this galaxy alone is 20 million. Which is damn impressive and completely reasonable.

The question of whether efficient, short-term space travel between one star and the next is even possible, however, is an entirely different question based on our own current and limited understanding of the universe and physics.

*sigh*

Posts like these are why telling children everyone's opinion matters is quite detrimental. Glad the proceeding posts came before I saw it. I'd hate to counter this.

The above post is likely a joke. Lighten up.

I was pretty sure you had no meaning behind your words. Might I suggest better word choice next time?

[DemolitionSquid]

I really need to start getting more specific. I keep forgetting everyone is a retard. The 20 million I started includes all the factors Gradius suggested: Goldilocks zone, gas giant asteroid blockers, civilizations rise and fall over time relative to estimated age of universe and time-displacement expansion. Gradius estimate of only 500 sentient non-radioactive species at any one time in the galaxy is still laughably low. Life on earth constantly proves how resilient and varied it truly is. To suggest that life on other planets would somehow be weaker or more stupid than life here is disgustingly arrogant. All those other species in Star Trek/Star Wars have good reason to hate humans in their respective fictional universes: we'll always find a way to be racist first.