Author Topic: Exoplanets  (Read 1944 times)

Online Mr.Obvious

Re: Exoplanets
« Reply #60 on: March 26, 2017, 05:19:52 PM »
The confusion arises because the word faith has become synonymous with believing in something regardless of evidence or even if evidence is contrary to a notion. Why do you think the geyser at Yellowstone park is called old faithful?

Because it doesn't cheat on it's wife with other geysers?
E = Mc²

In the end, we are all standing in the dark,
trying to figure out why we are here.
But let us not choose one direction
without proof of where it is headed.

Check your pocket for matches
so we can observe and learn together
as fast friends and relative idiots.

Offline Baruch

Re: Exoplanets
« Reply #61 on: March 27, 2017, 12:45:41 PM »
שלום

Offline Cavebear

Re: Exoplanets
« Reply #62 on: March 31, 2017, 05:27:13 AM »
The confusion arises because the word faith has become synonymous with believing in something regardless of evidence or even if evidence is contrary to a notion. Why do you think the geyser at Yellowstone park is called old faithful?

Your definition of "faith" seems close to accurate to mine, but with error.  Mine is "anything accepted without evidence and even in spite of it.  Something accepted or trusted as true in spite of factual information". 
Atheist born, atheist bred.  And when I die, atheist dead

Offline Atheon

Re: Exoplanets
« Reply #63 on: March 31, 2017, 05:48:11 AM »
I am either mathematician nor a statistician but with billions and billions of galaxies out there I think there is almost a certainty there are many planets capable of sustaining life. If there is life on this planet then the probability that there are many more is almost a certainty. It just doesn't make sense that there wouldn't be others. The non-statistician in me can't imagine only one planet sustaining life in the whole universe.
With an estimated 100 billion planets in the Milky Way alone, there is likely life elsewhere in the galaxy.

The Drake Equation comes to mind.
"Religion is regarded by the common people as true, by the wise as false, and by the rulers as useful." - Seneca

Offline Cavebear

Re: Exoplanets
« Reply #64 on: April 03, 2017, 03:53:45 AM »
With an estimated 100 billion planets in the Milky Way alone, there is likely life elsewhere in the galaxy.

The Drake Equation comes to mind.

I know the Drake Equation,  It needs a lot of additions these days.  The problem is "likely".  The universe might be filled with planets with sludge or even microbes.  Complex life is not so certain.  Mammalian-style life is less likely.  Intelligent life might be rare or even never developed elsewhere.

There are good reasons to think intelligent life will not come from the sea, from amphibians, or reptiles.  Or even most mammals. 

It seems to me that primates are required and even most planets that develop them won't advance to our level of sentience.  I think that is where the Drake equation fails.  There is a massive step between even primates and sentient versions.
Atheist born, atheist bred.  And when I die, atheist dead

Offline trdsf

Re: Exoplanets
« Reply #65 on: April 03, 2017, 01:16:11 PM »
The only real use for the Drake Equation is as a tool to frame one's thinking about ETI.  There are too many terms for which we do not have hard numbers, only extrapolations based on a single data point - us - and one simply cannot extrapolate from a single data point.

The Drake Equation also necessarily undercounts, since it doesn't address civilizations that have not developed detectable technologies, nor those with sufficiently efficient communications methods that there is essentially zero leakage to be detected at a distance.  So it only addresses technologically communicative civilizations: those that utilize some sort of broadcast technology that can be detected at a great distance.

As they say on public television, let's go to the tote board:


It's only in the last 20 years that we've started getting observational evidence for factors other than R* -- Drake was a good 35 years ahead of his time when he proposed it.  R*, the number of new stars 'born' every year, is estimated at between 1.5 and 3.  The two terms we've managed to fill in so far are fp and ne -- fraction of stars with planets, and average number of planets per star system that could support life.  As it turns out, fp approaches 1: nearly all stars have at least one planet.

Estimating ne is trickier, since habitable zones are variable, and detecting small rocky worlds like ours is difficult, but right now the estimations are between ten billion and forty billion, but there's a lot of variability because the data is sketchier.  And the number could be much higher, since this term is only looking at life of any sort, not complex and intelligent life.  Besides Earth, there are potential habitats on several other bodies in this system: Mars, Europa, Ganymede and Titan of course, but also Enceladus, Ceres, and even the upper atmospheres of Jupiter and Venus.

Everything else is purest guesswork, because from here on out we have nothing but speculation.  The terms fl, fi and fc are completely speculative: in order, the fraction that actually do develop life, the fraction of life that evolves into intelligence, and the fraction of intelligences that develop a technological civilization, and the only genuinely honest answer is "Who knows?"  These are, in many ways, a better indicator of the thinking of the person trying to do the equation than they are of the odds of intelligent life itself.

The last term, L, is the lifetime in years during which a technological civilization's broadcasts can be detected.  This may be a very small window: radio emissions are not much more than a century old here, and already our radio leakage has dropped significantly as communications technology becomes more precise and less 'sloppy'.  There is no RF, for example, from a fiber optic cable.  Transmissions to a satellite are tightly beamed to a specific spot, not broadcast wide and loud.  So the window of opportunity to 'hear' our incidental/accidental broadcasts is closing, after an extremely short time on the astronomical scale.  It may be that ultimately there will only be a bubble of radio emissions around us, slowly attenuating, and a mere 150-200 lightyears thick.  The odds of it passing a civilization at the correct time in their development for it to be detected before it drops to the level of background noise are small indeed.

Personally, I find the Seager Equation more sensible in terms of being able to make estimates on what we might be able to discover, since it is based on fewer guesstimates and is not quite so time-dependent as the Drake Equation.
"It's hard to be religious when certain people are never incinerated by bolts of lightning." -- Calvin and Hobbes
"I thought I committed regicide today, but I committed deicide!" -- Sadie Doyle, Beyond Belief

Offline trdsf

Re: Exoplanets
« Reply #66 on: April 13, 2017, 03:41:37 PM »
A newly announced discovery that's very relevant here: Enceladus almost certainly has hot fluid vents like the 'black smokers' on Earth's sea floors.

What that confirms for the first time is a known life-supporting environment somewhere other than Earth.  Needless to say, it doesn't confirm life.  Still, finding the necessary conditions is impressive.
"It's hard to be religious when certain people are never incinerated by bolts of lightning." -- Calvin and Hobbes
"I thought I committed regicide today, but I committed deicide!" -- Sadie Doyle, Beyond Belief

Offline Cavebear

Re: Exoplanets
« Reply #67 on: April 17, 2017, 05:04:49 AM »
I suspect there is pond scum all over the universe. 
Atheist born, atheist bred.  And when I die, atheist dead

Offline SGOS

Re: Exoplanets
« Reply #68 on: April 17, 2017, 09:39:44 AM »
We already have a time machine.  When we look at space through distance, we are seeing into the past.  I know you know that, just pointing it out. 

I suspect that, if we could reach distant planets, we would find microbial life abundant.  The universe might actually be filled with microbes.  The real question is if microbes routinely become more complex or not.  And whether any complex structures advance to technology.  And if they don't kill themselves off immediately. 
Not the best time machine, since it can't take you to when you want to be.  It only takes you to when something happened at your moment in time from when you currently are.  It doesn't increase your odds at seeing life.  Although, it might decrease your odds because as you see farther into the past, you are looking at systems that haven't had as much time to evolve life.

Microbes?  Yes, you have a better chance of seeing microbe infested systems in the early stages of development.  And of course some systems may have formed billions of years before Earth, and could be at a point where more advanced life could have evolved.  Unfortunately, by the time you traveled over there, who knows how many mass extinctions may have occurred, and whether or not any life still exists.  In fact, the entire system may have disappeared in the flash of a nearby supernova, which happened even before you located the then existing system in the first place.

I think the odds of life beyond our system are very good and even likely, but the odds of finding it aren't quite so likely.
« Last Edit: April 17, 2017, 09:41:30 AM by SGOS »

Offline trdsf

Re: Exoplanets
« Reply #69 on: April 17, 2017, 02:02:13 PM »
I suspect there is pond scum all over the universe.
Very probably; the speed with which it arose on Earth suggests that abiogenesis is the easy part, and the slowness with which it developed into complex life suggests that's not.

(obligatory disclaimer: yes, I know, drawing inferences from a single data point, yadda yadda yadda)

Finding life -- extant or extinct -- on Mars is important, but we know that material has moved back and forth between Earth and Mars, so cross-contamination is possible even without landings on the surface. 

This is not the case for Europa and Enceladus and Titan.  Anything we find there is going to be a separate origin; they're too far out for a plausible cross-contamination mechanism.  That's the real prize, if anything turns up out there.

Can't wait for the first mission to really sample the Enceladus plumes -- that they were able to get Cassini to do it at all is amazing, now we need a mission out there that's designed to specifically search for life.
"It's hard to be religious when certain people are never incinerated by bolts of lightning." -- Calvin and Hobbes
"I thought I committed regicide today, but I committed deicide!" -- Sadie Doyle, Beyond Belief

Offline Baruch

Re: Exoplanets
« Reply #70 on: April 17, 2017, 10:38:52 PM »
Panspermia ... the theory that life was seeded across the solar system by a giant dick ;-)
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Offline SGOS

Re: Exoplanets
« Reply #71 on: April 18, 2017, 05:11:39 AM »
Panspermia ... the theory that life was seeded across the solar system by a giant dick ;-)
Yeah, but what caused the giant dick?

Re: Exoplanets
« Reply #72 on: April 18, 2017, 06:06:31 AM »
Yeah, but what caused the giant dick?
It fell out of a quantum bag of dicks.

Offline Baruch

Re: Exoplanets
« Reply #73 on: April 18, 2017, 06:39:59 AM »
It fell out of a quantum bag of dicks.

Unfortunately a Heisenberg dick doesn't stay hard very long, the bigger the dick, the shorter the stay ;-)
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Offline SGOS

Re: Exoplanets
« Reply #74 on: April 18, 2017, 07:58:04 AM »
Unfortunately a Heisenberg dick doesn't stay hard very long, the bigger the dick, the shorter the stay ;-)
No, "the older the dick, the longer the stay."