I'm getting some popcorn!
There's bound to be microbes on some other planet out there... and finding them would only be the start! The real science begins when probes are sent to the planet to study their life forms!
I watched the "Europa Project" on Netflix last night. SciFi, but still fun to watch and dream.
If life is inevitable when there is liquid water, mankind (maybe not NASA) will find it in 20 years.
But, what if life is not common? Some things only happen once, even in near-infinitely large universes.
I don't think anyone said the liquid water makes life inevitable, but it certainly seems to be prerequisite for all life on Earth, so it probably is elsewhere.
Since we now have discovered exoplanets which have a good chance of liguid water, this does increase the liklyhood of life being discovered.
However we don't have any certainty of how life begins once water is present, it could still be the case that some other conditions are necessary, and those other conditions might be a lot more rare than the presence of water.
"I think we're going to have strong indications of life beyond Earth within a decade, and I think we're going to have definitive evidence within 20 to 30 years," NASA chief scientist Ellen Stofan said Tuesday during a panel event on water in the universe.
The statement is a reasonable one if, and only if, life is reasonably common in our part of the universe. The emergence of life is probably complex and we have only speculative notions as to the probability of each step in that complex process. Until we have expanded our knowledge of life beyond a sample size of one, such speculations are interesting, but barely constitute science.
We have found meteorites from Mars on Earth, so it's reasonable to think there might be meteorites from Earth on Mars and other bodies in the solar system. Thus, it's possible that material ejected from Earth could have seeded life throughout the solar system. While I would be extremely surprised to find evidence of an independent emergence of life elsewhere in the solar system, I would not be as surprised to find evidence of Earth-like microbial life in areas where there is water (e.g. on Europa).
But how many such locations in the solar system could have sustained life, had microbes from Earth ended up on them?
As for independent emergence of life, we cannot really speculate as to how improbable it is because life is a currently an unexplained emergent phenomenon to us... it could well be that life is truly a freak singular occurrence and the chances are miniscule of that repeating anywhere else in the universe, we won't know until we understand the biochemistry better (at least, I think...)
I've long believed that life beyond Earth would be proven scientifically within my lifetime. The problem I see is that it may not convince the general public, who wants to see little green men, not a spectrograph indicating an atomsphere that was probably created by microbial life.
I think you are overstating it. Abiogenesis is heavily studied and while it is difficult to prove exactly what happened, there is good lab evidence of the likely general phenomena.
I don't think there is good evidence. We can't even get steps of abiogenesis to happen even in controlled lab experiments.
Please provide citations supporting this assertion. We have fragments of processes that may or may not be part of the complete abiogenesis sequence. (Miller-Urey type experiments, or self forming lipid vesicles are examples.) They offer plausible partial pathways, but there is nothing like a cohesive, demonstrable route from non-life to life. I am completely with Almeisan on this one.
I have little doubt that we shall eventually determine, in great detail, how life arose, but we are presently very distant from that achievement.
Well the Drake equation certainly took a big jump up in numbers as it used to rely upon one planet per ten stars.
Admittedly, it is hard to imagine planets (much less planets with life) in binary star systems (and a large percentage of stars are in binary systems).
I am prejudiced into thinking intelligent life will be carbon based with an H20 requirement. However, basic rudimentary life could be based upon other liquids as well. Its just that many of these types of life forms may not be able to survive or evolve much past micro-organisms. In fact our Earth had only micro-organisms for the first couple of billion years as well.
Intelligent life of any measurable intelligence is only a very recent phenomena.
Well, the Drake equation is basically obselete at the moment because life on other planets is not a question of astronomy/planetary physics.
It is a question of biochemistry and biology.
We might set up a new Drake equation, but in most steps of abiogeneisis we know the odds are zero in our labs, giving lab experiment timescales.
Well, I also believe that dolphins could certainly evolve and surpass us (maybe even already have) in intellegence. However, without any means to affect their environment ie make tools, fire, metallurgy, history via the printed page etc. they will be forever constrained to the oceans. They could not develop any technical civilization and therefore not make themselves known nor travel anywhere off the globe.
If our earth had no protruding land mass so to speak, dolphins would be at the top of the evolutionary ladder and remain at their technological level for eons ie Zero technology. Similar creatures on other worlds could never really make themselves known nor travel off of their planets either.
Please reread carefully what I said: I think you actually did agree with me. I didn't claim we have a cohesive, demonstrable route from non-life to life, I said we have good lab evidence of the "likely general phenomena". "General phenomena" sounds an awful lot like "plausible partial pathways" to me. I purposely put several qualifiers in the post.
This is a big subject, but an example of the "general phenomean" studied in the lab is:
Anyway, I don't want to drag this off track - I don't think this is critical to the thread.
Well, I see a logistical problem here.
We think Mars suffered an impact spectacular enough to create the Hellas Basin on one side, the Tharsis Bulge on the opposite and split it like a gutted fish along the Valles Marineris. The poor planet practically burst like a balloon! So certainly energy to spare to fling rocks around the solar system.
But you're talking about an impact occurring after the creation of life. I'm just not sure that Earth has suffered sufficient insult recently enough to make this plausible.
Life sprang up on earth almost as soon as it became habitable - like a billion years after it formed. I think life is virtually inevitable anywhere else under similar circumstances. Complex life? - that may be an exophytic horse of a different color.
We have no idea how abiogenesis happened. Did it happen in a pond or tidepool? Did it happen in the deepsea near a smoker? We have no clue.
We think we need lightning or heat, or metabolism of reduced substsances, and now radiation is suggested as well. Basically, we have no idea which energy, if not metabolism, is the original driving force.
We think it started with RNA or something very similar, and that is logical, but we have no experimental data to show this is how it must happen. We have no clue what needs to happen first. Maybe vesicles are needed first.
We know that through several ways it is possible to make amino acids, make RNA, make vesicles. But we know that can happpen through controlled experiments.
All we know is that it happened and that it is not chemically impossible. We have no clue about the probability, except that it happened fast after conditions on earth made life possible (or so we are told by geologists).
And every time the issue is raised, the 60 year old Urey-Miller experiment is invoked. We struggle to deliberately make synthetic life de novo when we can do so much in both biochemistry and molecular biology.
Mars -> Earth meteorites are much easier than the opposite direction - a lower escape velocity and no atmosphere for most of the time.
The earth won't be able to support complex life for much longer than another billion years. If life would have evolved a billion years later, it might never have reached a species that can discuss this topic. The early evolution of life could have been necessary for our existence, so I would not take that as strong evidence for a likely evolution of life.
I'm really looking forward to that. Atmospheric gas compositions are fine.
I don't share Stofan's optimism, however, as long as we don't know how frequent life is and how often it leaves detectable traces.
Umm...isn't there a little bit of a conflict of interest here?
It's like Schwinn or Trek telling investors that bike ridership numbers are surely going to explode.
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