So what are we supposed to believe?

[MG1962]

I am referring to the fact that the conditions for life (including liquid water), originally assumed to exist only in the HZ, are now known to also be created by tidal forces in the moons of gas giants far outside it. I don't know why you assume that life which arose in such circumstances would be restricted to single cells.

But remember we dont know this as a fact yet. There is strong science that suggests it is a distinct possibility, but until we get some probes out there and possibly check one one of the cyrovolcanoes, exactly how much water is down there is a bit up for speculation.

On this subject watch the upcoming close approach to Pluto, there are some extremely interesting suggestions there could be liquid water below its surface as well.

 

[woodbutcher]

I seriously doubt that watching aliens go through their form of reproduction would be very sexually stimualting.

You underestimate our capacity for kinkiness!

 

[Fudbucker]

There are nearly countless planets in seemingly habitable zones. The key word here is "seemingly". Just how much of a niche zone does Earth occupy for life to develop? No one knows...

I posted this in an older thread, but it's worth reposting. Suppose there are at least 10 key factors that can only vary by 1% for life to develop (axial tilt, location of large gas giant, size of moon, variability of star, etc). If that's true, then we're probably the only life in this galaxy. If there are at least 15 key factors that can only vary by a small amount, then it's likely that we're alone in the universe.

With only one example of planet-based life, it's impossible to calculate the odds. Maybe there are only a few factors and they can vary by a wide amount. Then the galaxy would be teeming with life.

But there have been some findings that support the rare-Earth hypothesis (that life is incredibly rare in the universe):
1. The absence of any kinds of von Neumann probes
2. The absence of galaxy-wide colonization attempts
3. SETI's failure to detect an alien signal
4. No evidence of Type 3 civilizations (civilizations that would harness the power of an entire galaxy) in a survey of 100,000 galaxies
5. And, of course, no visits (or invasions) so far by little green men. Unless they're already here...

I'm not arguing that this is compelling (or even strong) evidence. There are perfectly valid reasons why evidence of alien life hasn't turned up yet. But the results so far have been disappointing, and when we examine Europa and Titan, and eventually the atmospheres of nearby exoplanets, I think we'll be in for more disappointment. My gut feeling is that life is probably pretty rare, multicellular life is very rare, and advanced intelligent multicellular life extremely rare. Maybe only one per galactic cluster.

 

[Pianoro]

On this subject watch the upcoming close approach to Pluto, there are some extremely interesting suggestions there could be liquid water below its surface as well.

Flyby on July 14. I expect nothing less than great tiers of terraced towers built of black stone, black rivers of pitch and cyclopean bridges.

MG1962, do you know how we might go about learning about possible subsurface water on Pluto and Charon with a one time flyby? Tectonic activity evident on the imagery comes to mind. Is there anything else New Horizons can do?

 

[MG1962]

Flyby on July 14. I expect nothing less than great tiers of terraced towers built of black stone, black rivers of pitch and cyclopean bridges.

MG1962, do you know how we might go about learning about possible subsurface water on Pluto and Charon with a one time flyby? Tectonic activity evident on the imagery comes to mind. Is there anything else New Horizons can do?

The first indicator is going to be if Pluto has an equatorial bulge. If it does, it means the games up and nothing to see. As the probe gets closer the nature of any surface fractures will help. Some types of fractures will occur because the water underneath froze and expanded, typically these would run for very long distances. Others will be stress fractures caused by the water moving around under the surface.

 

[abaddon]

The problem with that assertion is that woo carries no information. Information cannot travel faster than the speed of light, but disinformation can.

OK. Could we use disinformation as some sort of carrier wave for actual information?

 

[Trakar]

Life does not equal ET. Life on Earth has been around for 3.5 billion years. Life capable of communicating across the stars, less than 100 years

Perhaps it is as simple as realizing that there is a big difference between our current assessments of "inhabitable" planets (any body orbiting its star in the proximate zone of water's triple-point) and planets with the potential to have actually generated life. Even within our own system, persistent life only appeared and proliferated on one, rather unique planet (that we can tell so far). I'm not saying that life in the universe is one example rare, but merely that it quite well may be much more rare than many ETL enthusiasts hope for. As you mention, this may well be further complicated by the fact that life does not automatically lead to complex life, yet alone intelligent technological life.

 

[MG1962]

Perhaps it is as simple as realizing that there is a big difference between our current assessments of "inhabitable" planets (any body orbiting its star in the proximate zone of water's triple-point) and planets with the potential to have actually generated life. Even within our own system, persistent life only appeared and proliferated on one, rather unique planet (that we can tell so far). I'm not saying that life in the universe is one example rare, but merely that it quite well may be much more rare than many ETL enthusiasts hope for. As you mention, this may well be further complicated by the fact that life does not automatically lead to complex life, yet alone intelligent technological life.

Yeah I agree and I do blame the media for a lot of that. The number of headlines that scream "Earth Like Planet Found" translates to the only similarities is they are both round

 

[Pianoro]

The first indicator is going to be if Pluto has an equatorial bulge. If it does, it means the games up and nothing to see. As the probe gets closer the nature of any surface fractures will help. Some types of fractures will occur because the water underneath froze and expanded, typically these would run for very long distances. Others will be stress fractures caused by the water moving around under the surface.

Thanks. I read up on this a bit more. Very interesting. I'm looking forward to see what New Horizons sends back.

 

[Ziggurat]

OK. Could we use disinformation as some sort of carrier wave for actual information?

Unfortunately not. Any information you try to combine with your disinformation will simply be corrupted beyond recognition in the process, with no way to extract it afterwards.

 

[Elind]

I read two science articles. One said that astronomers have discovered what could be 11 billion planets in the goldilocks zone hinting that there could be life on these planets. Then another article soon after said that astronomers after careful study of the universe they could find no sign of an advanced civilization or even a hint of life.

So what should a layman be thinking?

There are not 11 billion planets discovered, goldilocks or not. There are enough planets discovered to extrapolate what is probably out there, and in terms of godilocks there are probably billions more of what we would call satellites around planets.

As to what laymen think; they think what they want to think; usually independent of known facts.

 

[Elind]

The problem with that assertion is that woo carries no information. Information cannot travel faster than the speed of light, but disinformation can.

Nifty comment. Needless to say disinformation doesn't need to travel, it just appears at (or comes out of) the source, like magic.

 

[jonesdave116]

Okay, let's look at a typical net article. This one is from April 18th 2014:
A better than 50/50 chance Kepler-186f has technological life.

The article goes into a lot of detail about how the signals are detected and analyzed. However, let's look at the planet itself.

It orbits the star, Kepler 186, which is a type M1 red dwarf.

The only stars that are expected to have life are F, G, and K. Our sun is type G which is in the middle of this range. Stars half the mass of our sun would require the planets to be in so close that they would get tide-locked. And, stars more than 1.5x the mass of our sun burn too hot and fast. BTW, when I suggested that the habitable zone extended from Earth to Mars, that is for a type G. It would be in a little closer with type K and out a bit farther with type F.

So, based on the star alone we can assume there is zero chance that Kepler 186f has life. But, let's look at the planet itself.

Kepler 186f is about 1.15 Earth radii or about 30-60% more mass. So, with a sun like ours it would need to be a little farther out in its orbit.

Kepler 186 only has 4% as much solar radiation as our sun. So, you would need an orbit of about 0.2 AU. Kepler 186f is at 0.38 AU which would make it too far away if it were Earth sized. However, the extra mass makes it about right. However, with an orbit at about where Mercury is, this planet would be tide locked. This may not make sense to everyone. Basically, the star is about half the sun's mass so gravity is about half. However, since gravity is the inverse square of the distance, you get 1/0.38^2 = 7. Divide by two and you get 3.5X the gravitational attraction that the Earth gets. This would tide lock the planet.

I believe tidal locking may not be the "game over" scenario it was once thought to be though. Suggestions have been made that a thick enough atmosphere, and/or an ocean, could redistribute the heat , preventing freeze out of the atmosphere on the dark side. Flares may themselves may not be as big a problem as previously thought either.

Tarter, et al.
http://online.liebertpub.com/doi/abs/10.1089/ast.2006.0124

On a related note, although I'm not putting it forward as "evidence", I recently read Stephen Baxter's "Proxima" 1 & 2. Excellent sci-fi, and based on such a planet around our nearest neighbour. Well worth a read if you get the chance.

 

[epepke]

If the second study be what I think it was and what I read, they were only looking for emissions in the middle infrared which would be expected if most or all of the galaxy was colonized and a very large chunk of the total output was used to run equipment similar to what we have. I think that the universe could be teeming with life, even intelligent life, without being like that.

 

[Trakar]

Nifty comment. Needless to say disinformation doesn't need to travel, it just appears at (or comes out of) the source, like magic.

sounds like a potential artifact of FTL transit.

 

[Skeptic Ginger]

You underestimate our capacity for kinkiness!

Hi, welcome to the forum. I think you'll fit in very nicely here.