So...let's talk about Aliens...

[A wilding]

Holy delayed response!

Not an expert, but IIRC I meant Gliese 667C, about which more there has been more news since:

http://www.bbc.co.uk/news/science-environment-23047504

Edit: Gliese 581 is another possible candidate.

[The Mance]

The star is less hot than our sun but the planets are close enough that their surface temperatures should be about the same as Earth's, which could mean they have water.

Do they presume an atmosphere when they make surface temperature comparisons like this? Or do they mean the same as earths would be without our atmosphere?

[Cato.the.Elder]

Math is math regardless of our senses. Ditto for physics. In fact, they are hard to understand in part because once you get to a certain level (multivariate calculus, complex analysis, quantum mechanics, relativity), it becomes very difficult to relate them to our everyday lives. Of course, any aliens will almost certainly have formulated the laws differently -- even among human beings there are multiple formulations of many mathematical and scientific ideas -- but these formulations identical in substance.

I'm not sure about that. Math is math because of how our brain works. I don't think a different species would have the same math as we have. And physics is just a posible model (the best we've been able to create until now) of our perception of the universe (which is not the Universe itself, as it has been proccessed by our brain).

[A wilding]

Edit: @ The Mance

Again, not an expert, but yes.

As I understand it we can only determine the approximate mass and distance from their sun of these planets. From that we can calculate the likely surface temperature and see if it is in an Earthlike range. They are basically saying that these planets may have surface temperatures in this range.

Surface water is generally only possible when there is an atmosphere, otherwise it would simply evaporate away. Planets have to be a certain mass to keep an atmosphere, I believe it is currently assumed that most planets above this mass are likely to have one.

[Sci-2]

The Man Who Speaks for Earth

Recently, at a mass in Vatican City, Pope Francis said that, if given the chance, he would baptize aliens. (“Who are we to close doors?” he asked.) Unfortunately, judging by “Archaeology, Anthropology, and Interstellar Communication,” a new book, about the complexities of communicating with extraterrestrials, released last month by NASA, it won’t be that simple. For a long time, the people most interested in searching for extraterrestrial intelligence came from “hard science” disciplines like astronomy or physics; to them, the main obstacles seemed technical (building radio telescopes, processing signal data). But, in recent years, the field has broadened to include people who already study other civilizations here on Earth. In these essays, they report that their jobs are hard enough as it is. Archaeologists struggled to decipher ancient Greek; deciphering a transmission from another world will be even more difficult. Even if we do manage to detect a signal, they write, fully understanding what it means may be impossible.

[Clueless Northman]

Archaeologists struggled to decipher ancient Greek

Wait, what?

Ancient Greek has always been known and immediately readable and understandable.

Linear B, ancient writing system of the Mycenaeans, was quite puzzling at first and scholars weren't even sure it was propre Greek until they deciphered it, though. Linear A is still a mystery, as is Etruscan language - though that one is actually deciphered.

But indeed, seeing how we have trouble understanding fellow humans, even civilizations we have some understanding of, this doesn't bode very well for us being able to translate the kind of messages aliens would send.

[SpaceChampion]

An alien intending to be understood will send the cheat sheet first.

[Crixus]

http://waitbutwhy.com/2014/05/fermi-paradox.html

Excerpt: Scientists estimate that there are over 100,000 intelligent alien civilizations in our galaxy alone—but we’ve never heard anything from any of them. Here are 13 possible explanations for why.

[Ghjhero]

http://waitbutwhy.com/2014/05/fermi-paradox.html

Excerpt: Scientists estimate that there are over 100,000 intelligent alien civilizations in our galaxy alonebut weve never heard anything from any of them. Here are 13 possible explanations for why.

That was an awesome article, thanks for sharing!

[sologdin]

this thread would deliver better if we had an actual abductee boarder tell us about clandestine alien probings.

[Clueless Northman]

this thread would deliver better if we had an actual abductee boarder tell us about clandestine alien probings.

Does having played South Park - the Stick of Truth qualifies?

[sologdin]

well, we have almost 89,000 members. an old poll on alien abduction in the US found 119 abductions out of 6000 respondents, which is roughly 2%. that means we should have approximately 1780 abductees on the forum.

[A Bong of Ice and Fire]

A few years ago I saw a squadron of cigar-shaped UFOs over the Chesapeake Bay in Virginia. They were moving slowly one after another, then all quickly dashed off and disappeared. Then another line of them appeared and did the same thing. Got to watch them for a couple minutes or so. Most definitely they were not animals or airplanes. Can't say they were aliens, but they certainly were UFOs. It was fascinating.

[ThinkerX]

http://waitbutwhy.co...mi-paradox.html

Interesting article, but way optimistic for the numbers of sunlike stars and earthlike planets.

There is not just a 'habitable zone' around individual stars, there is a 'galactic habitable ring', for want of a better term. Stars orbiting too close to the galactic center are subject to fierce bursts of radiation; while stars orbiting too far out tend to be very low in metallicity - which you need for planets.

Plus there be a whole bunch of other lethal weirdness out there. Is the star in a multiple system? Orbital eccentricity of the planet? Size of the planet?

The main thing working against SETI, though, is signal scatter. Or look at this from the POV of an alien civilization 50 light years off with a tech level about equal to ours. Yes, we humans have been broadcasting signals into space for longer than that, but over a fifty light year distance, the signal scatters, becoming little more than background noise. At best, said alien's would pick up a rare puzzling fragment. Even if we selected the aliens star and broadcast a directional transmission at them, it would still devolve to mostly noise.

Now there have been a couple of signals which could be scattered versions of ET transmissions.

[Crixus]

That was an awesome article, thanks for sharing!

Cheers! :)

[Lily Valley]

Nice article.

I have always loved Asimov's hypothesis that the moon was responsible for our evolutionary history. He suggested that such a large satellite was unusual and it brought heavy radioactive metals closer to the surface than they would normally be. Exposure to the radiation caused mutation to happen much more quickly, hence we get fast forward evolution.

It fits in nicely with the filter behind us hypothesis. It also appeals to my romantic sensibilities about moon worship. I'm not going all yoni-power here. That big rock up there is freekin beautiful. Just LOOK at it.

[Gucci]

Aliens aren't real. If they are well never come in contact with them.

[natty bumppo]

The earth is 4.5 billion years old. We have been transmitting radio signals for a hundred years. That means there is a chance of one in 45 million that a random habitable planet is inhabited by a civilization on the same level as ours. Not very favorable odds for SETI. Now the chance for intelligent life out there is much larger of course, but most of it has to be either in the stone ages or far ahead of us.

[Horza]

It's been ages since I studied this topic, but I remember being thoroughly impressed. Not only does it hold water when put next to the original but Aliens also manages to be a pitch-perfect action movie, making skilled use of a great cast and generally being awesome. On the rewatch pile, for sure.

[Jo498]

Very nice article, thanks for the link.

I tend to agree that some choices are too optimistic. I remember that less than 20 years ago (before Hubble etc. got going) there were plausible estimates that planets, especially earth-like ones, were exceedingly rare. Now this has been turned completely around: Planets are plentiful.

So I guess that some other estimates could still err in being way to optimistic. I also believe that there may be far harder thresholds or filters of physical impossibilities. There are many possible "extinction" events for planets in otherwise habitable zones. One those only has to occur every billion years or so to destroy live (until it may begin after another billion years or so). There may be millions of life forms, but all between monocellular organisms and "type 0.5" civilization, none or few of which have developed radioastronomy.

A dilemma of many of those theories is that these estimates are on the one hand (of course) based on our current knowledge on physical laws etc. On the other hand the wilder theories seem to imply that this current knowledge could be (and are probably is) extremely far from the way the universe really is, because they entertain the possibility of "type III" civilizations which are more or less secularized gods, angels or demons with their fantastic powers.

If our knowledge of the universe may be at least as wrong as Aristotelian physics and a geocentric model were, or maybe closer to the "worldview" of ants, why should I trust in any estimate developed on the basis of this state of knowledge?