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Old 01-03-2016, 20:33
brangdon
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The only way I could see human beings able to interact with other intelligent beings is if 1) They came here, or 2) we build large space ships/societies in the FAR FAR future that people just lived on traveling through space, kind of like nomads (think Battlestar Galactica). And then it would just be sheer coincidence that they bumped into each other. God help those poor aliens if that happens.
I like David Brin's approach in Existence:
Spoiler


That aside, I have been wondering about how rare the various features of our solar system are. Earth having a large moon, for example, may turn out to be crucial. Apparently it arose from a collision in the early solar system. Presumably from computer simulations we can now estimate how common such collisions are. Similarly the chances of having a Jupiter that is distant from its sun rather than close in. If it's true that life first arose on Mars and migrated to Earth, and if it turns out that it has to happen like that, how common is it to have two planets in the Goldilocks zone? Is it possible we are at the end of a long line of astronomically unlikely events?

(Although most of the time I think life is common and intelligent life - or even multi-cellular life - is rare.)
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Old 01-03-2016, 20:41
WhatJoeThinks
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I would think that on a planet where single-celled lifeforms exist, multi-cellular lifeforms are inevitable, given enough time. Whether you'd end up with simple sponges and the like and nothing more I'm not sure. Not every rung of the evolutionary ladder is equally spaced, so to speak.
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Old 01-03-2016, 21:11
brangdon
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I would think that on a planet where single-celled lifeforms exist, multi-cellular lifeforms are inevitable, given enough time.
As I understand it, simple single-celled life arose on Earth almost immediately conditions were suitable. Complex, nucleated single-celled life took a couple of billion years. Multi-cellular life took roughly another billion. May be it is inevitable, but those are long time spans, even compared to the age of the universe. If it usually takes 20 times as long, there just hasn't been enough time.

Of course that's begging the question. We don't know if it is like pregnancy, which always takes nine months (more or less) because it involves a set number of events that have to happen in order, or if it is random. It seems mitochondria arose because one cell didn't properly digest another, which seems very unlikely in itself rather than something quickly inevitable once the precursors were around. That it apparently only happened once (that we know of), adds to my suspicions. This despite the entire surface of the planet being covered in simple single-cellular life that it could have happened to.

Nor do I think it inevitable that multi-cellular life on any given planet would become intelligent. The dinosaurs didn't. And again, I'm talking about within the lifetime of the universe, which is what we have to work with. There's no "given enough time" here. And let's not forget we need heavy elements like carbon to make life, and those take time to forge, so you don't even get the whole universe lifetime.

I'm being optimistic here. I'm saying the Great Filter lies behind us, and colonising the galaxy will be easy from here on in. Someone has to be first.
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Old 01-03-2016, 21:31
WhatJoeThinks
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Of course that's begging the question. We don't know if it is like pregnancy, which always takes nine months (more or less) because it involves a set number of events that have to happen in order, or if it is random. It seems mitochondria arose because one cell didn't properly digest another, which seems very unlikely in itself rather than something quickly inevitable once the precursors were around. That it apparently only happened once (that we know of), adds to my suspicions. This despite the entire surface of the planet being covered in simple single-cellular life that it could have happened to.
As I understand it, eukaryotes evolved due to a string of such events. By the fourth (?) 'inclusion' things really began to diverge and compete, accelerating the evolutionary process. I expect similar processes are occurring on billions of exoplanets, and have done so throughout the history of the Universe.

I completely agree with you about intelligent life though. The Earth is about 4.5 billion years old, yet homo sapiens have only been around for a few hundred millennia... and you still rarely meet an intelligent one.
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Old 04-03-2016, 22:06
Keyser_Soze1
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Hubble has detected the most distant galaxy yet discovered.

For now at least - just wait until the James Webb Space Telescope is launched.

http://phenomena.nationalgeographic....least-for-now/

http://phys.org/news/2016-03-hubble-...-distance.html
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Old 04-03-2016, 23:17
cobaye22
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As I understand it, simple single-celled life arose on Earth almost immediately conditions were suitable. Complex, nucleated single-celled life took a couple of billion years. Multi-cellular life took roughly another billion. May be it is inevitable, but those are long time spans, even compared to the age of the universe. If it usually takes 20 times as long, there just hasn't been enough time.
Yet we still can't replicate this process.
Never mind the Eukaryotes, which require speculation and hand waving.
The transformation of chemistry into biology seems unknown.
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Old 04-03-2016, 23:22
RobinOfLoxley
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The Lottery is known, but we can't pick the right numbers. Still people win.

I am not a biochemist.
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Old 04-03-2016, 23:37
gkec
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Yet we still can't replicate this process.
Never mind the Eukaryotes, which require speculation and hand waving.
The transformation of chemistry into biology seems unknown.
We can't replicate the Big Bang but that doesn't mean it didn't happen.
You have written three hand waving statements without any reference to what you are talking about.
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Old 05-03-2016, 01:10
cobaye22
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You have written three hand waving statements without any reference to what you are talking about.
Always wanted to be a prof
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Old 05-03-2016, 08:54
njp
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Always wanted to be a prof
... essional creationist?
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Old 05-03-2016, 11:11
brangdon
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Yet we still can't replicate this process.
I think that's the difference between trying it in a few test tubes in a few labs over a few years, and trying it in every drop of ocean over an entire planet over a few million years. Something vanishingly rare in the former could be common in the latter.
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Old 05-03-2016, 13:29
codeblue
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Did someone say "dinosaurs were not intelligent" ?

What a stupid thing to say., for many, many reasons.
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Old 05-03-2016, 13:44
TelevisionUser
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I think that's the difference between trying it in a few test tubes in a few labs over a few years, and trying it in every drop of ocean over an entire planet over a few million years. Something vanishingly rare in the former could be common in the latter.
When conditions on Earth became conducive for the development of primitive life forms, it might have taken millions, or tens of millions, of years for replicating organisms to appear and evolve and branch out. So far, research was only really started after WWII and even today while the subject is of great interest, there are relatively few groups (and insufficient funding) around the world studying the origin of life.

All those factors put together mean that there are still so many unanswered questions which need to be addressed, e.g. where and in exactly what conditions did life evolve.
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Old 05-03-2016, 13:56
TelevisionUser
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Hubble has detected the most distant galaxy yet discovered.

For now at least - just wait until the James Webb Space Telescope is launched.

http://phenomena.nationalgeographic....least-for-now/

http://phys.org/news/2016-03-hubble-...-distance.html
I think that one of the important things to note there is that galaxy formation started not too long after the origin of the universe itself, i.e. a few hundred milion years and I daresay that the James Webb telescope will be able to look back even further and see even earlier galaxies.
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Old 06-03-2016, 02:05
Keyser_Soze1
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Did someone say "dinosaurs were not intelligent" ?

What a stupid thing to say., for many, many reasons.
Corvids and parrots would have something to say on the matter as well.
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Old 06-03-2016, 11:05
brangdon
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Did someone say "dinosaurs were not intelligent" ?

What a stupid thing to say., for many, many reasons.
In this context, "intelligent" means human-like, to the level of building radio telescopes or similar so they can interact with species on other planets. If anything, animals like Corvids show that a species can get so far and then not go any farther. I dare say some dinosaurs had Corvid-levels of intelligence, and yet never went on to forge iron or steel. It suggests to me that human-level intelligence is not inevitable even given multi-cellular creatures. (Admittedly the timescales here are much shorter - around 150 million years - so there's more room.)
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Old 08-03-2016, 00:13
HenryGarten
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How Richard Nixon saw the future of the space programme 46 years ago
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Old 08-03-2016, 00:21
Keyser_Soze1
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Why Mercury is so dark and a very mysterious mountain on Ceres.

http://phys.org/news/2016-03-mercury...-revealed.html

http://news.discovery.com/space/aste...oto-160307.htm
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Old 08-03-2016, 02:34
balthasar
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Rather good pictures, it is a planet that gets overlooked........
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Old 08-03-2016, 08:39
Heston Veston
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Hello? Dark because it's so close to the sun? Obvious!

Nobel prize please...
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Old 08-03-2016, 23:58
HenryGarten
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Total eclipse of sun in progress right now. It is live on a number of sites.
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Old 09-03-2016, 23:29
atg
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Hello? Dark because it's so close to the sun? Obvious!

Nobel prize please...
Are you suggesting it's just a bit charred?
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Old 10-03-2016, 02:32
Keyser_Soze1
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"The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of starstuff."

http://phys.org/news/2016-03-interstellar.html
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Old 11-03-2016, 21:58
Keyser_Soze1
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Some interesting recent astronomy articles.

http://news.nationalgeographic.com/2...res-science/#/

http://news.discovery.com/space/what...ice-160311.htm

http://phys.org/news/2016-03-star-fo...tar-kappa.html

http://news.discovery.com/space/vide...deo-160310.htm
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