Have Aliens made contact?

We do have observable proof of aliens visiting.




Mayflow

:panic:

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Originally Posted by Omnis Dei

Occam's razor. Because we can't find the end, it's simpler to believe the universe has no end than imagine a wall. Occam's razor also points toward aliens existing. It's much simpler to imagine we aren't the only mistake in this vast thing than try to fathom how an occurrence like this happens only once.

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Hey guys cant we all just agree to stop (mis)using Occam's razor. Its a pretty lame (lack of) argument.

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Originally Posted by Xei

Occam's razor really isn't a stringent inference, especially in situations like these where 'simplicity' is an very ill-defined term. An infinite universe could equally be said to be a lot more complex than a finite one. Not that I'm saying I believe the universe is finite; but you can't really form any kind of conclusion at all about it. In the second case a similar argument would argue that there are many other Jim Careys throughout the universe; it's a simpler assumption than the idea that he could just happen once by mistake.

Although to be honest, we should only be concerned in this thread with the observable universe anyway, because that's the only thing that can causally interfere with us. And once we know more about the chemistries of other planets and about the development of life, it will be perfectly possible to start putting numbers on these probabilities.

And there are other valid inferences. It really does seem unlikely that there are any technologically advanced races within our galaxy who want to advertise their presence.

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Not Jim Carreys, but Jim Carrey look alikes, which there are. The point is not that the exact formula replays, but that life finds a way.

That is not a general principle. Life arises in special circumstances.

Basic understanding of emergence suggests otherwise but you know what? Go ahead and be right. It's all you want, isn't it?

Ok, I'll make a serious post in here. All the talk has been about physical beings from other planets in the known universe so far - but Omnis specified physical or otherwise on the OP.

My belief is that all non-physical beings, inorganic and otherwise, are from the unconscious - realm of archetypes, gods, demons, aliens, ghosts and a whole passel of other types. Not from outer space, but inner.

Or you could just throw a huff because somebody disagreed with you again, sure.

Emergence does not state that life arises as a general principle. Emergence isn't a general principle. Play Conway's Game of Life with different laws. There are hundreds of different settings. Patterns happen very rarely, and actual complex emergence only happens once.

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Originally Posted by Xei

Or you could just throw a huff because somebody disagreed with you again, sure.

Emergence does not state that life arises as a general principle. Emergence isn't a general principle. Play Conway's Game of Life with different laws. There are hundreds of different settings. Patterns happen very rarely, and actual complex emergence only happens once.

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I don't even understand how to begin to respond to this. Emergence is everywhere in the natural world.

Life emerges in special circumstances, how rare are these circumstances? I suppose it could be 1 in how ever many planets there are in the observable universe, but I see no reason to think that conservatively, our galaxy alone could be teaming with life.

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Originally Posted by Omnis Dei

I don't even understand how to begin to respond to this. Emergence is everywhere in the natural world.

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Yes. The natural world. On Earth. Which has the aforementioned special circumstances.

As far as life emerging under special circumstances, I heard of an interesting experiment.

A scientist heated beach sand to a point where it should kill almost all known bacteria and placed it in a sterilized jar. He then put that in an autoclave sterilizer which should kill all remaining life.

After 24 hours DNA formed, along with simple microscopic lifeforms.

Here is a thread which describes it, with various links for reference at the bottom. Scientific Evidence for DNA spontanously forming from only sand and water in sterile environment

The implication is that life can arise without reproduction. Though as Xei mentioned, this happened on earth (of course) and so far no microscopic life has been found on the moon or mars.

Spontaneous generation is a myth

http://www.dinosoria.com/insectes/mo...mestique-1.jpg

Ya it would sort of take the fun out of propagating life, eh? ;)

That is almost definitely junk science; the guy has just redetected the contaminants. DNA is a very complex molecule, and requires elements not even present in just water and sand.

There has been lots of good research in this area though. One of the most famous experiments of all time is the Miller-Urey experiment, where they basically created Earth's early atmosphere in a jar, and the basic substrates of life formed by themselves (sugars, fats, and amino acids, the building blocks of proteins which are responsible for all complex structures). A later experiment by Jean Oro showed that nucleotides (the basis of genetic material) can also form.

All that needs to happen for life to start is for a strand of these nucleotides (i.e. RNA, the precursor to DNA and still used in cell machinery) that catalyses its own production to form, and that would cause a chain reaction that could be acted on by natural selection; this requires no novel chemistry, but nobody knows the probability that such a molecule could form. It could be that it's extremely improbable, and Earth was just the lucky planet amongst all the planets with Earth-like atmospheres. The other unknown is how many planets have such an atmosphere, and what kind of variations also permit such a process.

I don't think we should assume contaminants just because traditionally DNA needs more elements from which to form. Perhaps DNA will form with whatever elements are available. Though, again, no DNA on mars.

However I agree that there is no guarantee that those processes killed every single iota of life in that jar.

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Originally Posted by Xei

Yes. The natural world. On Earth. Which has the aforementioned special circumstances.

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Galaxies, dude.

A spiral is a pattern.

Did you know dolphins are related to dogs? Not every sea-going creature has to start in the ocean.

I don't understand what you're saying. Of course I know that dolphins are mammals..? This is called convergent evolution; 100 million years ago there were aquatic reptiles called ichthyosaurs which looked very similar to dolphins, too.

A spiral isn't a complex pattern capable of accumulating information. It's really rather simple. All examples of emergence that aren't life are very simple indeed, as far as I know. Crystals are homogeneous molecular structures with straight edges; stars and planets are spheres. None of these things even approach the qualities of life.

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Originally Posted by Tranquil Toad

I don't think we should assume contaminants just because traditionally DNA needs more elements from which to form. Perhaps DNA will form with whatever elements are available. Though, again, no DNA on mars.

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Sorry no, this makes no sense at all. DNA forming out of sand and water would be like an edible cake forming out of iron. The basic elements of life cannot change into one another (except by nuclear reactions which require temperatures of 100 million degrees or so); the whole of nature has had to work around this by forming cycles of the finite material.

Maybe they have, maybe not. It depends on how we look at it really. We are all hoping to either catch them on our satellites (if you're interested in this topic, google SETI's Alien Telescope Array) or for them to descend in their great big spacecrafts. In my opinion, if they were really as intelligent as we sometimes think they are (thank you Hollywood), then they would make contact in a more intricate and subtle way.

Yeah I'd imagine they'd make contact at a distance before startling us.

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Originally Posted by Tranquil Toad

However I agree that there is no guarantee that those processes killed every single iota of life in that jar.

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It doesn't really matter if it killed everything or not. DNA isn't alive.

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Originally Posted by Xei

Or you could just throw a huff because somebody disagreed with you again, sure.

Emergence does not state that life arises as a general principle. Emergence isn't a general principle. Play Conway's Game of Life with different laws. There are hundreds of different settings. Patterns happen very rarely, and actual complex emergence only happens once.

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Xei doesn't understand how life arose, therefore life is rare in the universe. Because Xei is the all-knowing Asperger's sufferer.

When did I even say that? People have made very good guesses as to how life arose with no conceptual gaps, but it's all qualitative. Nobody has actually been able to put a number on the probability yet. I didn't say life is rare, I said it might be rare. You really can't tell the difference between these two statements? Oh wow.

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Originally Posted by Xei

Emergence does not state that life arises as a general principle. Emergence isn't a general principle. Play Conway's Game of Life with different laws. There are hundreds of different settings. Patterns happen very rarely, and actual complex emergence only happens once.

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^ Xei using the tried and tested proof by unrelated example to show that life is rare in the universe.

Xei, I have one problem with your arguments. And you had a similar thing in another thread.
But I found it hard to put it in to words until last night when I was thinking about it.

You seem to sort of take the argument to the extreme of "what if?"

Like we already know some of the necessary components for life to arise.
But you're saying, if we find more necessary components then it would lower the odds of life arising on other planets.

But you're meant to be going with the information we have right now.

Which is the correct use of Occam's Razor.
Not presuming too much.

But you always seem to presume that things will be more complicated.

Going on the information we have right now, we could say (cbf looking up real numbers) that there are 10 Earth-like planets in our galaxy. There are 10 trillion galaxies. So there are probably 10x1,000,000,000,000 Earth like planets in the Universe.

But the way you argue, I would expect you to say "Oh yeah but you don't know what unobservable galaxies are really like.... maybe none of them are hospitable to life because of their position in the Universe and some unknown factor could cause their to be no usable atoms to create proteins." Or something like that.

You have to assume every other galaxy is at least similar to ours, and thus Earth-like planets in those galaxies, capable of supporting life. Otherwise we'll never know until we actually see them. And then what's the point of doing the numbers and predicting in the first place?

You can't base your argument on unknowns.

No, I was just clarifying why it's not totally beyond the limits of possibility that life could be very rare, due to the exponential nature of the drop off in probability. Often people think that, for life to have an extremely low probability (which would of course be necessary if life were rare in our colossal universe), life would have to require thousands and thousands of different conditions with small probabilities; in reality you only need a very moderate number of unlikely factors.

It was just an explanation of how the maths works for those not mathematically inclined. Discovering new factors is not supposed to represent some real event; it's just an analogy to explain how the existing factors (and exactly how many of those there are is not known), whatever they are, if they are moderate in number, could reasonably conspire to create a small probability.