Are we alone?

[modest]

:lol: i was thinking last night after i posted that that was the 10 molecules, but it was late so i didn't come back. nevertheless, it's good enough for who it's for, so let's run with it.

 

I'm sorry, T :doh: The 36 million years was 50 molecules. All these numbers has done confused me.

 

But, ok, I'm all for running with the 50 molecule example

 

first, sagan aside, how long did it take to write

[math]10^{10^{21}}[/math]

?

 

Ok... I think about 10^20 seconds. There are 10^21 zeros, so writing 5 zeros a second would take 2 x 10²⁰ seconds. That's about 6 x 10¹² years. I thought it would be a bit more, to be honest. It's 'bout 440 times the age of the universe... to write the number in decimal :eek_big:

 

how long for me to imagine it once written?

 

or to forget why you were writing all those zeros in the first place ;)

 

i get a little cheesed when big numbers are thrown up as scary impediments to knowledge. :naughty:

 

Sure I still wouldn't bet on winning the lottery though :shrug:

 

oh yeah, big number. alright, let's take just your 10 molecule black swans expected 1 every 36 million years. now a 14 billion year universe, so we could expect over 300 10 molecule half-gassed glasses to surprisingly, impactily, justifiable-after-the-factily to occur. oui/no?

 

Yup

 

what i'm getting at is that the probability calculation says nothing about when these events, or any probabilistically determined event, happen. when these terms are used, there is a fallacious implication that such things happen "once every" expected time period, when in fact the events could happen in the allotted time all in a row, or not happen at all yet, or a few here, a few there, or in any random order.

 

Yeah, I think "on average once every..." would be most accurate. While it could happen quickly it's probably helpful to think in terms of looking at the glass when the molecules are randomized (or when they've had time to randomize from the last time you looked) and having a one in 1,000,000,000,000,000 chance to observe the event. Even with only 50 molecules it seems to me rather mind boggling.

 

~modest

[modest]

We have never seen it rain on an alien planet. Yet, we can say that it is inevitable to have it rain on other planets, because that is how liquids act under certain circumstances.

 

Yes / no?

 

Yes, rain is not an unknown process that requires unknown conditions, just like fusion is not an unknown process requiring unknown conditions. Abiogenesis is an unknown process requiring unknown conditions. Rain and fusion are described well by falsifiable theories with predictable experimental results. Abiogenesis is none of that.

 

Really, I feel like I'm speaking a foreign language here. Moontanman, we keep going over the same points. You say fusion hasn't been observed in the center of the sun as if my objection is that we've never observed life on other planets. My objection is that you cannot logically attribute a probability to a completely unknown process.

 

When someone offers up a 'theory' of intelligent design we smack them about with the scientific method saying their idea makes no predictions, is not falsifiable, never been tested, etc. How is the same method so easily tossed aside when the hypothesis sounds agreeable?

 

The great advantage of the scientific method is that it is unprejudiced: one does not have to believe a given researcher, one can redo the experiment and determine whether his/her results are true or false. The conclusions will hold irrespective of the state of mind, or the religious persuasion, or the state of consciousness of the investigator and/or the subject of the investigation. Faith, defined as [*] belief that does not rest on logical proof or material evidence, does not determine whether a scientific theory is adopted or discarded.

What is the ``scientific method''?

 

We can assume that spontaneous generation of flies from rotting meat is inevitable. But, until there is a falsifiable theory explaining the appearance of larva on rotting meat which makes predictions that can be tested, it is an assumption—an untested hypothesis. That's just the way science works, does it not?

 

~modest

[Boerseun]

Complex amino acids are easily made when flasks filled with gas simulating Earth's early atmosphere are sparked.

 

And life arrived on the scene almost as soon as the conditions were right.

 

When we're discussing alien life, we will obviously never know. But if it turns out that life is merely what chemicals in the right quantities under the right conditions get up to given enough time, then yes - I would say that it is inevitable.

 

DNA is amazing - sure. But there are many other combinations that can conceivably replicate themselves. So, be it DNA or any other imagined self-replicating molecule, the fact that they are all chemical in nature, speaks volumes. Chemistry, like physics, work the same no matter where you are. Lighting a match in an oxygen-rich atmosphere will work wherever you are.

 

I think the issue boils down to chemistry.

 

I will concede that "inevitable" might be a strong word, a bit too absolute given the evidence, but then the fact that life appeared almost immediately once the conditions were right on Earth, is a very strong argument in favour of life being nothing more and nothing less than what hydrogen, nitrogen, carbon etc. get up to given the right conditions.

[Moontanman]

Yes, rain is not an unknown process that requires unknown conditions, just like fusion is not an unknown process requiring unknown conditions. Abiogenesis is an unknown process requiring unknown conditions. Rain and fusion are described well by falsifiable theories with predictable experimental results. Abiogenesis is none of that.

 

Really, I feel like I'm speaking a foreign language here. Moontanman, we keep going over the same points. You say fusion hasn't been observed in the center of the sun as if my objection is that we've never observed life on other planets. My objection is that you cannot logically attribute a probability to a completely unknown process.

 

When someone offers up a 'theory' of intelligent design we smack them about with the scientific method saying their idea makes no predictions, is not falsifiable, never been tested, etc. How is the same method so easily tossed aside when the hypothesis sounds agreeable?

 

What is the ``scientific method''?

 

We can assume that spontaneous generation of flies from rotting meat is inevitable. But, until there is a falsifiable theory explaining the appearance of larva on rotting meat which makes predictions that can be tested, it is an assumption—an untested hypothesis. That's just the way science works, does it not?

 

~modest

 

My point is that abiogenisis is not a completely unknown process, we know bits and pieces of it, we see why it happens, we even see how, just because the process is not known in complete detail is no reason to say we cannot predict the process happening. If you can read the links i provided, the books i quoted, and not see how life is as inevitable as crystals or rain or any other natural process then maybe I am just too ignorant to understand.

 

I know you are more knowledgeable in the scientific method than i am but i think we can extrapolate from the evidence we do have to say life is inevitable under the correct circumstances. i also think it's reasonable to say the correct circumstances come about quite easily, inevitably, when planets are formed, if i have to bow to greater knowledge then i bow to you.

 

But to me what you are saying smacks of the creationist argument that life is a unique process that requires unique conditions that require the supernatural to happen. This idea plays into the idea of creation not science. I'll stop this before I become a troll but i honestly think i provided ample evidence of the inevitability of life in those links, it would be redundant to provide more links that say the same thing.

[sman]

.... alright, let's take just your 10 molecule black swans expected 1 every 36 million years. now a 14 billion year universe, so we could expect over 300 10 molecule half-gassed glasses to surprisingly, impactily, justifiable-after-the-factily to occur. oui/no? what i'm getting at is that the probability calculation says nothing about when these events, or any probabilistically determined event, happen. when these terms are used, there is a fallacious implication that such things happen "once every" expected time period, when in fact the events could happen in the allotted time all in a row, or not happen at all yet, or a few here, a few there, or in any random order.

 

so in conclusion, i conclude. a little early & blurry here; will check back later.

 

So if we were to determine (somehow) that there must be about 1500 technological civilizations in our galaxy (of ~5billion star systems?) and then went about calculating the average distance from earth to the closest one - which is where I was taking this thread - we are basing this on a model of our galaxy in which technological civilizations are evenly distributed throughout, which is not realistic. Probability approaching zero. Chances are 1500 random events would be lumped into clusters here and there.

 

How's that, sensei?

 

I've already stated that I think the contact idea is unrealistic. Further, I wanted to make a strong statistical argument that would justify my attitude (or change my mind, if the numbers went that way). So... without the statistics :) I don't have an argument. It may be that the nature of randominity logically precludes this argument. I dunno...I'm still reading on it.

 

As far as the contention that life is inevitable - this strikes me as fallacy of a different flavor: failure to recognize the middle ground; false dicotomy. I am arguing that life is rare. Opposition needn't declare that it is inevitable. It would suffice to argue that it is likely.

 

And of course, there's always medium-rare for fence-sitters. :D

[Moontanman]

I was able to back up my assertion with cutting edge information, have you backed up your assertion with anything other than "it just can't be so?" Life is not a random event, your assertion it is a random event is a strawman argument.

[freeztar]

The main problem: We can't prove that life is inevitable. (no falsifications)

 

Is it likely? Maybe. :)

 

This does Not mean that I advocate teleology or theology.

 

Are we alone?

I think I already answered this. Yes. We are alone. What's wrong with that?

[modest]

So if we were to determine (somehow) that there must be about 1500 technological civilizations in our galaxy (of ~5billion star systems?) and then went about calculating the average distance from earth to the closest one - which is where I was taking this thread - we are basing this on a model of our galaxy in which technological civilizations are evenly distributed throughout, which is not realistic. Probability approaching zero. Chances are 1500 random events would be lumped into clusters here and there.

 

That’s a fun and interesting problem that was recently solved here on Hypo:

 

21509

 

It may be counterintuitive, but the random distribution (not the uniform distribution) has the closer nearest neighbor. In other words, if civilizations were placed randomly around the galaxy then we would expect to find one closer to us than if they were placed uniformly throughout. In fact, since we have the formula at hand, let’s use your numbers. If there were 1500 civilizations and the volume of our galaxy is roughly 3.897 x 10¹³ lightyears cubed then the density of civilizations is:

density = 3.84878 x 10

^-11

civ/ly

³

If these civilizations were uniformly placed throughout the galaxy then we’d expect to find one every,

density

^-1/3

= 2961.8 ly

2961.8 lightyears. That’s how close the nearest civilization would be to any other civilization on average if they are placed uniformly. If they are placed randomly where there will be clusters and whatnot like you say then the nearest neighbor is:

0.55396/density

^1/3

= 1640.7 ly

1640.7 ly. So, you’d expect to find another civilization closer to you if they are randomly distributed verses being uniformly distributed.

 

~modest

[modest]

My point is that abiogenisis is not a completely unknown process, we know bits and pieces of it, we see why it happens, we even see how, just because the process is not known in complete detail is no reason to say we cannot predict the process happening.

 

Before the ensuing brouhaha I had posted on this. Perhaps something like:

Perhaps.

 

If I handed you a box and told you the thing inside involved plastic and ink could you tell me if it is unique or if there are other things of the same general form all over the planet?

 

Could you assume it were a playing card and judge its uniqueness off that assumption?

I couldn't recall it quite as well as the last post. Perhaps you read it. Any case, I'm sure my point was that knowing something about X does not necessarily allow you to judge x's uniqueness. In the case of abiogenesis, I think this is true. Knowing whatever we know about it (i.e. it involves water, carbon, and amino acids, etc.) does not allow us to judge its uniqueness.

 

~modest

[Moontanman]

I think it's interesting to note that if aliens are so far away, 1600 light years on average, then none of them could possibly be aware of us and if the following is correct it's unlikely we could detect them!

 

Maybe it's a totally loosing proposition to begin with!

 

Aliens can't hear us, says astronomer | Science | guardian.co.uk

 

"For good measure, in America we have switched from analogue to digital broadcasting and you are going to do the same in Britain very soon," Drake added. "When you do that, your transmissions will become four times fainter because digital uses less power."

 

"Very soon we will become undetectable," he said. In short, in space no one will hear us at all.

 

Then there is always the more controversial

 

Top 10: Controversial pieces of evidence for extraterrestrial life - space - 04 September 2006 - New Scientist

 

If indeed we find life on Mars and or other places in the Solar System what does this say about the inevitability of life?

[freeztar]

Neil Degrasse Tyson was on the daily show Monday night.

 

Full Episode | March 1, 2010 - Neil DeGrasse Tyson | The Daily Show

 

He made the claim that if we find a planet with lots of oxygen it is indicative of life as oxygen has a short lifespan in the atmosphere if it is not constantly being produced from life. I did a quick search and only found one article about a planet that was found to have lots of oxygen, but it was found to have an orbit closer than Mercury and all the oxygen is being flung from the planet by jets of Hydrogen gas that were being pulled off by tidal forces. :singer:

 

He also made the claim that the presence of methane on Mars is indicative of anaerobic life, which I found surprising. Has anyone heard this claim before?

[Moontanman]

Neil Degrasse Tyson was on the daily show Monday night.

 

Full Episode | March 1, 2010 - Neil DeGrasse Tyson | The Daily Show

 

He made the claim that if we find a planet with lots of oxygen it is indicative of life as oxygen has a short lifespan in the atmosphere if it is not constantly being produced from life. I did a quick search and only found one article about a planet that was found to have lots of oxygen, but it was found to have an orbit closer than Mercury and all the oxygen is being flung from the planet by jets of Hydrogen gas that were being pulled off by tidal forces. :singer:

 

He also made the claim that the presence of methane on Mars is indicative of anaerobic life, which I found surprising. Has anyone heard this claim before?

 

A quick search turned up these links

 

Q: Why does oxygen necessarily indicate the presence of life? « Ask a Mathematician / Ask a Physicist

 

The only known process that actually releases O2 into the air in any real quantity is photosynthesis. So, observing oxygen in the atmosphere of other planets implies photosynthetic life.

 

http://earth.rice.edu/shows/scripts/fantasy_worlds-script.pdf

 

Sunrise over Mono Lake reminds us that Earth’s atmosphere

protects billions of life forms. Our air contains nitrogen, oxygen

and water vapor – an unstable mixture that indicates the presence

of life. Oxygen is a reactive gas that must be constantly resupplied

by the Earth’s green plants. Detection of oxygen, carbon dioxide

and water vapor in the atmosphere of an alien planet would

strongly suggest suitable conditions and the presence of life.

 

Hunting for life in alien worlds

 

But finding both oxygen and a gas like methane in the atmosphere would really clinch the argument for an alien biosphere. Oxygen and methane react together very rapidly in planetary terms, and so finding them both side by side in an atmosphere means the chemistry of the planet is far from equilibrium. Something has to be continuously producing both gases in enormous volumes: life. Intriguingly, plumes of methane gas have already been discovered seeping out of the ground on Mars. Perhaps these are the waste gases given off by hardy bacteria living deep beneath the freezing martian surface.

 

I would seem that it takes more than oxygen to suggest life. Oxygen can exist from other novel methods that have nothing to do with life but on an earth like world the presence of oxygen, methane, CO2 and Ozone would appear to be highly suggestive of life. Just oxygen can occur in unusual places from just as unusual reasons but these are not earth like planets at the correct distance from their star for water.

 

Two Earth-sized bodies with oxygen-rich atmospheres found, but they're stars not planets

[Pyrotex]

Every time I've read books on planetology and deep space sensing, everyone seemed agreed that the presence of oxygen would have to indicate life. There just aren't any low-energy, non-Life processes that free oxygen, which is so reactive that it WILL combine with something. Because there are no solid Teflon planets out there.

 

Methane isn't reactive but it's fragile. Sunlight from blue and up into the UV will disassociate it rather quickly. You might find methane collecting in an atmosphere of a planet very distant from its star (like Titan) or of a planet around a red dwarf star that emits no UV.

[Moontanman]

It would seem that oxygen under all but the most extreme conditions would indicate life. Methane can be produced by non biological methods but life seems to be the most likely source of methane as well. Thomas Gold predicted that Mars would have what we call fossil fuels due to biology reworking geology. Now if we could just go to Mars and do some real exploring maybe some of this will be less speculation and more reality.

[Jay-qu]

Are we alone..

 

..in the universe? Certainly not

 

..in the galaxy? Probably not

 

..in the solar system? Probably

 

..on Earth? No

 

..at home in the middle of the night? If your lucky: No

[Boerseun]

We are confronted with two hypotheses:

 

1) Life is inevitable given the right circumstances

2) Life is not inevitable

 

These hypotheses are mutually exclusive, and impossible to prove with any sort of finality either ways. The term 'inevitable' is a bit too absolute.

 

But then you consider the argument put forward by Morowitz & Smith in 2006 that life is basically 'forced' into existence by thermodynamics. Life is merely a chemical transport channel, as well as a conduit for built-up chemical energies to dissipate. Granted, their work is still in progress, and they do concede that there's nothing final to it. But if they get around to clinching their idea, then yes, life is inevitable given the right circumstances. Basically like lightning is inevitable given the right circumstances as a conduit to relieve electrical stress in the atmosphere - yet you cannot predict how and where it will happen.

 

The thing is, both sides of the argument is mere speculation. You saying it is not inevitable is as absolute as me saying it is. We simply don't know - but there sure is very compelling arguments both ways.

 

I tend to go with the 'inevitable' idea. And, if these guys are on to something that Life is merely driven by thermodynamics, and the relief of chemical stresses, then surely intelligence is something to be selected for - humans, after all, is the only species on the planet able to use energy extrasomatically. Intelligent life will then be much more beneficial in relieving the 'chemical stress' of so much hydrocarbons lying just a few miles under a perfectly good oxygen atmosphere. There is no other process or natural mechanism that can bring underground oil and atmospheric oxygen in contact with each other. But then we are natural, are we not? At what point did the humans leave the natural world? We might be a horribly efficient erosion agent (acid rain on rocks, open-cast mining), we might be a severely strict evolutionary selection sieve (animal husbandry, agriculture) but nothing that we are and nothing that we do came from anywhere but Mother Earth. We are the result of natural selection, ergo, we are natural. A bit off the scale compared to other animals, but we're animals, nonetheless. So maybe we should get off our high horse when considering the uniqueness of intelligence. Some animals have spots, some have brains. The odds (and purpose) for having them are the same.

[coldcreation]

We are confronted with two hypotheses:

 

1) Life is inevitable given the right circumstances

2) Life is not inevitable

 

[...]

 

I tend to go with the 'inevitable' idea. [...]

 

I would bet on number 1 also, if given the choice.

 

It seemed inevitable hear on earth to say the least, even under extreme conditions (i.e., of the early pre-Cambrian era, or at the bottom of the oceans where volcanic vents are open and operational).

 

So, to imagine that life exists elsewhere beyond the solar system is not a great leap of faith. Especially considering all the organic material floating around in space.

 

The idea that (number 2) life is NOT inevitable seems to require some mechanism that would actually prevent, or at the very least hinder the development of life, such as climate or chemical abundances. It seems that as long as climate permits and chemical abundances allow, then life is inevitable, in its most simple form, no matter where life originates or where its 'seeds' come from. And that, just as the formation of complexity is inevitable from simple organisms.

 

So not only would life appear inevitable but so would complex forms of life (such as trilobites or humans), given the proper climatic conditions, chemical abundances. thermodynamic processes.

 

So to answer the OP, I would say we are most definitely not alone.

 

CC