Why Life Might be Rare

Discussion in 'Science and Nature' started by Sam_Spade, Aug 3, 2011.

1. This paper was published a couple weeks ago. Give me your thoughts.

2. It makes a lot of assumptions. I was able to follow most of the math behind it, but it seems like what they're calculating is the probability of abiogenesis occurring on Earth, rather than the probability of life on other worlds.

Besides, statistics mean nothing on individual cases. When abiogenesis occurred on Earth, the probability of it occurring could have been 0.0000000000001 or 0.99999999999999999999. We don't know.

An interesting read, but I don't think it's anywhere close to a definitive answer.

3. Well abiogenesis is the study of how life can form from inorganic matter from natural processes such as evolution as we see on Earth - it also pertains to life on other worlds. However, i agree with you on the mathematics - it does assume that other lifeforms with similar intelligence to us would have to arise from a similar progression in time - it also refers a lot to the capabilities of humans as an indication of the limits of life, whereas i do not see how this has any relevance to the matter at all, why does the idea of 'cosmologically curious' beings have to be incorporated into the mathematics? That is purely conjecture.

While i do believe that life is a lot rarer and more pristine than some give it credit for - especially the UFO nuts - but this paper leaves out many variables; and supposes on many of those that it uses, using our individual experience as a species to sculpt the equations which while audacious, i think it reeks of importance. Like you i think this concept will have to be left to physical evidence rather than unfair guess work leading to equations that propose a definitive answer.

4. it's really simple to disprove. first off there are way too many assumtions for it to even be vaild. and secondly, at the simplest form, life is really only a self replicating, chemical reaction. so really, any planet that has the componets for life(chemicals, temp, ect), has a good shot of having life at it's simplest form. by pure probibility, the number of planets that have these fetures is uncomprehensable. Kepler telescope was only launched a little while ago and already there are tons of planets that could possiably support life. just think what else is really out there seeing we have checked out like 1/9823902348956315628975689234562356298560294359078567389047893467438943578904389578906756789268902378947289072572097896689289237862896289078927692672890376 to the 897457892378923789897457843578962589629875628567490078080254786086723457892780606268240507w0786890th of star systems out there. yeah theres a "w" in there, thats how big it is!!!
peace

5. The authors of this paper are very attentive to their assumptions and err on the side of generous rates. Are their specific assumptions you find untenable?

I was able to follow most of the math behind it, but it seems like what they're calculating is the probability of abiogenesis occurring on Earth, rather than the probability of life on other worlds.

Well that's not really what they're calculating. The using a model of statistical distribution, and illustrating that the proposed biophilic nature of our planet, is consistent with abiogenesis being rare. They're effectively eroding the very argument that because our planet seems biophilic, there are other frequent opportunities.

The realities of stellar physics and planetary geochemistry seem to be pretty hostile to life, especially when you start dealing with the added factor of time. It generally doesn't increase survival probability of life, it reduces it.

And knowing what we know about biochemistry and planetary physics, supportable models have been proposed. The authors use the results of these studies, and intentionally a wide range of estimates. Look under the sections A Poisson or Uniform Rate Model as well as A Minimum Evolutionary Time Constraint and The Likelihood Term.

Definitely not a definitive answer. But a worthy and weighty perspective to consider, perhaps?

You have to be careful with this claim. Although we know the constituents for organic life can be easily-formed and are found throughout planetary bodies; we have never been able to recreate abiogenesis. Maybe someday, but currently not so.

Until we do, we cannot assign a definitive value to the likelihood of abiogenesis, but we do know it's not exactly as simple as the slush of a stray asteroid.

We have dozens of worldlets in our very own solar system, and spy no sign of life yet. No photosynthetic organisms, no visible bacterial colonies, no products of known metabolism. We have more exploring to do, but it certainly seems like does not reliably yield from it's constituent components. Probability and luck seem to be a factor in some regard.

The article doesn't say humans are the only life -- it says that abiogenesis may very rare, despite our existence. If abiogenesis is indeed rare, then even without considering possible dynamics of global cultures; these civilizations may exist too far apart to be meaningful. It's a very real possibility, it's been a serious consideration in SETI policy-making for decades.

6. Life was unicellualr for a long time, and probly resembled prions before that.

Earth is extreamly well protected, and near perfect for long term life.

The rarity of abiogenesis combined with the long term investment needed for evolution to speed up, any cellular life is going to be rare, and multi cellular life is prbly like trying to find truffles.

7. Yes, I'm familiar with the Poisson distribution. It's basically an extension of the binomial distribution over continuous time periods. It calculates the probability of events occurring over a certain time. They're calculating the probability of abiogenesis based on the only confirmed case we have. We know it occurred about 3.5 billion years ago. We've only seen it happen once. Not a good idea to base your statistics around a single observation.

Hostile to life as we know it. It's foolish to assume all life is like us. The fact that we have extremophiles living on our own planet should be evidence enough that life is very resilient and can live almost anywhere.

Maybe. But the truth is, we will never know until we KNOW. And we probably won't KNOW until much after any of our lifetimes.

But how many of those have we THOROUGHLY examined? We've looked at the moon and Mars. And we haven't even looked at that much of Mars (only the surface). That's pretty much it. Think about all of the other planets, moons, asteroids, and other random objects in our solar system.

Like I said, we won't know until we KNOW.

8. I've been using, for some time now, the fact of Earth's seemingly quick abiogenesis as just the "optimism" for extraterrestrial life the authors talk about.

I try to be as intellectually honest as possible, but I could feel myself loathing the possibility of relinquishing this evidence; as I read the paper, this manifested itself as the dim hope they'd find evidence that at least one of the 3.5 billion-year old single-celled organisms used a molecule completely other than DNA, thereby pointing to 2 independent abiogenesis events in the same time frame and planet; no way in hell they could chalk it up to chance then.

Oh well, rare or not, I figure the universe is sufficiently large to bring life in abundance; I just want to imagine the galaxies to be teeming with life forms.

9. Life isn't rare,
It would be very rare to find a planet that is very similar to ours, but life is very adaptable. Life on earth evolved with what Earth had, water and CO2 which plants adapted to and they released oxygen over millions of years until oxygen was plentiful then life adapted to that by evolving into insects an animals and shit. Theres a moon in our solar system (i forget which planet the moon is from) where methane is to that moon as water is to our planet. On this moon, methane can be found as a gas, solid, and liquid. Conditions on earth only allow methane to be a gas naturally. Water on this moon is just ice because it is so cold. We could send a bacteria that is adapted to methane and send it off to the moon and let it evolve into life that would adapt to those conditions

10. If that's the case, then why can't life adapt to live on any planet and why does it need specific things to survive?

Also life can't form with oxygen in the atmosphere, it would begin to oxidize any amino acids the instant they're formed. But if there were no oxygen then how did water come into being? Also if there was no oxygen then there also couldn't be any ozone, and if there's no ozone UV rays from the sun would destroy all the ammonia needed.

11. well my friend. allow me to enlighten you for all these concerns have been met by scientists.

first of all, oxygen in its gas state doesn exist naturally in atmospheres. The ogygen in the atmohpsere was created after photsynthesizing bacteria started producing it from CO2. Now the reason CO2 and H2O exist is because oxygen exists. The reason oxygen isnt in the atmosphere is because it quicky reacts with everything forming oxodized agents.

oh and did i mention that life formed in the water so oxygen gas wouldnt be around to kill it even if it was in th atmosphere

If there was no photoshynthesis, earths atmosphere would not have oxygen; because the oxygen would be heald in things like CO2 and oxodized minerals and whatnot.

Ammonia has been seen in vast quanities all throughout space, and would likely exist on earth as well. UV rays do not penetrate soids, or deep oceans.

Here is a theory on how it started.
proteins formed
enzyms formed
cells formed
dna formed
maybe not in that order

chloroplasts formed. They created oxygen, which created an atmosphere, which allowed other types of life to evolve.

As life evolved, it became more and more adapted at different enviroments as the earth changed, and recources became limited. This is why you dont see life everywhere. Primitive life is still fragile. It has to evolve before it can exist in places like yellowstone hotsprings.

12. So fragile, yet so resilient.