Cosmic census finds crowd of planets in our galaxy

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Re: Cosmic census finds crowd of planets in our galaxy

Postby classical piano guy on Thu Feb 24, 2011 3:24 am

TreeHandThing wrote:
truthiness wrote:What about intelligent life discovering us first? It seems likely to me that there is probably at least one other intelligent civilization somewhere in the Virgo Supercluster that is already 100 million years old (or more). As you say, it'd be extremely pessimistic to believe that such an ancient civilization hasn't already found us. To go a little farther out on the limb, I doubt that such a wise civilization would still be mucking around with sluggish radio communication that travels at merely the speed of light. Do you really think we'll be the first ones out of the gate?


The Virgo Supercluster is gigantic. I'd say that there are at least 4 other intelligent civilizations in the Virgo Supercluster.


I entered my own estimations into the Drake equations and obtained a result of about 1 existing, intelligent civilization per 50000 galaxies. However, all predictions are pointless, and labels of optimism/pessimism spurious because the so called "probability" of alien life is completely weighted -- and our knowledge of many of the contributing factors is still severely limited. In other words, "there are trillions of planets; therefore, there are probably several planets with life" -- or even "there are many planets capable of supporting life; therefore, intelligent life must have developed somewhere" -- is a non sequitur.

Also bear in mind that only second generation stars like our sun even have the elements necessary for life (first only has hydrogen), so it's essentially impossible for any intelligent species to have evolved too long before us. For all we actually know, we could be the first (I don't believe that, but there's certainly no current evidence which disproves it). On the other hand, there could be millions of advanced lifeforms in the Milky Way only a few months from discovery.

Regardless, I'm viewing these planetary discoveries as potential candidates for the future migration of mankind, rather than as current habitats for other life.
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Re: Cosmic census finds crowd of planets in our galaxy

Postby crzer07 on Fri Feb 25, 2011 2:06 am

I wish there was an HD version.

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Re: Cosmic census finds crowd of planets in our galaxy

Postby TreeHandThing on Fri Feb 25, 2011 2:17 am

Beautiful. The music reminds me of the Walking With... series'.
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Re: Cosmic census finds crowd of planets in our galaxy

Postby Craven on Fri Feb 25, 2011 11:14 am

classical piano guy wrote:(...) and our knowledge of many of the contributing factors is still severely limited. In other words, "there are trillions of planets; therefore, there are probably several planets with life" -- or even "there are many planets capable of supporting life; therefore, intelligent life must have developed somewhere" -- is a non sequitur.

Also bear in mind that only second generation stars like our sun even have the elements necessary for life (...)

Exactly. While that equation makes a lot of sense there's currently no way to solve it. But we begin to fill it. We have pretty much good estimation of how many stars are out there, Kepler constantly raises number of planets, also fraction of those in green zone...

And yeah - we need at least second generation stars, but keep in mind that most of early first generation stars lived for very short time, producing massive ammounts of heavier elements, so from what I know most of Milky Way stars are metal-rich. Another factor is distance from galaxy core, too close and radiation is unbearable for complex molecules.

But back to Drake. So we're close to having three numbers filled, and they alone give us millions of planets that could harbor life, even with very low percentage of those where life appears and where intelligence emerges numbers are high. Also I think fc is near 1. Unless intelligent race isn't wiped out by comet or something, they'll most likely have telecommunication devices and it's logical to use radiowaves, probably same as we, since I don't think they'd enjoy noise during their conversations. There are however two other factors - fL, and it's a damn strong limitation, when you realise we're listening for ~100 years, while sitting in 100,000 ly wide galaxy. Also let's assume that there are averagely 6 civilisations here:
1- That's us.
2 - Right now they are bacteria, that's forming planet's atmosphere. They'll be there in few million years
3 - They use spears, give them few thousand years.
4 - They have alien coca-cola, enjoy swimming, and colonised three bodies in their star system, working on interstellar travel. Too bad they're on other side of Galaxy core, no signal from them will pass through galactic bulge, and radiation from our big fat black hole.
5 - They had steam engines when meteorite killed them. There are dinosaurs out there now ;)
6 - That's another civilisation like us, maybe even more romantic, with antennas pointing everywhere, constantly spamming galactic message of love, but they are 5,000 ly from us, so we won't hear from them in some time.

So even with crowdy galaxy there's still plenty of reasons why we got nothing so far.


Second factor is that we're not sure (afaik) how would our TV signal look like at distance of 1000 ly. Would it be anything more than slight noise? What if it turns out that... I dunno... Oort cloud itself dims our signals. Maybe it's just ain't that easy to catch signales from ET. One thing that's pretty sure is that sufficiently advanced civilisation would be easier to spot - disappearing stars would be good indicator :) But was there enough time for such to emerge?






TreeHandThing wrote:Beautiful. The music reminds me of the Walking With... series'.

That piece comes from "Total Recall", it's , I love this track.
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Re: Cosmic census finds crowd of planets in our galaxy

Postby ExplorerAtHeart on Fri Feb 25, 2011 3:51 pm

Our present forms of communication ie. radio seem to fade into the interstellar radiation after a few light years or so. The power is too low, we would need a butload of power to transmit a radio waves that would go more than a few hundred light years.

So alien radio waves could be washing over us right now but are indistinguishable from the background hiss. We need to develop the tech to pick these signals out or develop the next form of communication that more advanced civilizations might use.

Yay to 400 posts!
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Re: Cosmic census finds crowd of planets in our galaxy

Postby TreeHandThing on Sat Feb 26, 2011 1:47 am

ExplorerAtHeart wrote:Our present forms of communication ie. radio seem to fade into the interstellar radiation after a few light years or so. The power is too low, we would need a butload of power to transmit a radio waves that would go more than a few hundred light years.

So alien radio waves could be washing over us right now but are indistinguishable from the background hiss. We need to develop the tech to pick these signals out or develop the next form of communication that more advanced civilizations might use.


Our civilization's radio messages to space fade to background hiss before they even reach Proxima Centauri.
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Re: Cosmic census finds crowd of planets in our galaxy

Postby Craven on Sat Feb 26, 2011 9:19 am

So while there most certainly can be lots of civilisations out there, SETI may be just a big waste of time. Anyone has some references for that signal fading? I mean it should be enough to compare power of our average average signal and of background noise, as power fades with r^2.


BTW - do you know if power of signal sent to Gliese is strong enough for 20 ly distance?
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Re: Cosmic census finds crowd of planets in our galaxy

Postby MissTomorrow on Mon Feb 28, 2011 9:52 pm

classical piano guy wrote: For all we actually know, we could be the first (I don't believe that, but there's certainly no current evidence which disproves it).


Lots of peopl have suegestted that. Theres a rather romantic feeling to the idea that WE are the 'elder race'... even if it will be lonely out there.
that thousands or millions of years from now, primitive aliens will look up to humans as shining beings from the sky.. to them, we will be the angels.

On the other hand, there could be millions of advanced lifeforms in the Milky Way only a few months from discovery.


I can't imagine them all being discoverd at once :) Unless maybe theres a Galactic Federation of millions of races, who are waiting for us to reach some abstract tech threshold before they contact us and offer us membership?
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Re: Cosmic census finds crowd of planets in our galaxy

Postby ExplorerAtHeart on Tue Mar 01, 2011 1:16 am

There has to be a first.
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