A universe full of dead aliens

ps200306

josip wrote: »

What about a nuclear winter?

I guess you might see some kind of dust or soot signature (lots of infrared). Possibly indistinguishable from a volcanic winter or a space impact winter, but in any case only lasting a few years before the dust falls out so the chance of catching one in the act would be very small.

Gwynston

Interesting article discussing the role that Earth's geological activity plays in life on the planet, and the repercussions for finding extraterrestrial life:

The unexpected ingredient necessary for life

ScumLord

seamus wrote: »

"Similar level of evolution" is something of a misnomer. There are no "levels" of evolution, nothing is "more evolved" than anything else.

Evolution doesn't have a set path that it follows where it is trying to achieve peak intelligence. Intelligence is an emergent property of evolution under certain conditions.

I'm sure crocodiles and sharks would say to wait another 10 millions years and if we still look the same as we do now we can start talking about being better evolved.

Another thing I don't hear mentioned much is the fact that the universe probably wasn't capable of supporting life for the first few million/billion years.

We are told we are made from star dust, which is true, so that would mean the first solar systems probably didn't have the required elements to make even the most basic forms of life.

When the second round of stars came about would their solar systems still be pretty low on heavy elements making life still very difficult or unlikely? For all we know our star which I heard somewhere is a third generation star is the first star that had enough star junk orbiting it to allow life to form.

We could be at the start of biologies life span rather than half way through.

Even though life has been around for billions of years on this planet it barely clung onto existence in the early stages of this planet. Life didn't get properly complex until the dinosaurs came along. Humans where a complete accident of climate change. Without that accident there's no reason to think another intelligent animal would have evolved to fill our place.

For all we know earth provides very specific conditions that allow life to thrive, and complex life can only form under the exact conditions that happened on earth. We don't even know how essential the moon was to that evolution. It could be that we will find basic single celled life all over the place but only earth sized planets with a moon will create complex life.

It all depends on what we find on the other planets, but even then we can't say that any life we find in our own solar system isn't just contamination from earth.

mickmackey1

ScumLord wrote: »

We are told we are made from star dust, which is true, so that would mean the first solar systems probably didn't have the required elements to make even the most basic forms of life.

When the second round of stars came about would their solar systems still be pretty low on heavy elements making life still very difficult or unlikely? For all we know our star which I heard somewhere is a third generation star is the first star that had enough star junk orbiting it to allow life to form.

Stars that end up as supernovae go through their lifetimes extremely quickly, on the order of around 10 million years. So several generations could come and go in the blink of an eye, astronomically speaking. Therefore plenty of opportunity for life to exist billions of years before now.

Capt'n Midnight

ScumLord wrote: »

Another thing I don't hear mentioned much is the fact that the universe probably wasn't capable of supporting life for the first few million/billion years.

We are told we are made from star dust, which is true, so that would mean the first solar systems probably didn't have the required elements to make even the most basic forms of life.

Yes you need a star going through the CNO cycle to make Carbon Nitrogen and Oxygen, and you need that star to go supernova to get those elements expelled from the star.



Silicon dioxide makes up most of the crust of this planet. And most animals and plants ignore silicon. You are most likely to encounter it in the stings of nettles. Similarly Iron , Aluminium and Magnesium make up most of the rest of the crust and again are only used as trace elements. Apart from Oxygen and Hydrogen we only use rare elements from the crust. Calcium we use in bones and things but bacteria don't really need it.

But biological systems are very good at concentrating stuff they do need.

So scarcity of elements isn't a show stopper. And once you leave the top rows of the periodic table elements can substitute to some extent. Arsenic for phosphorous , Strontium for Calcium. We use iron to carry oxygen, other organisms use copper. Tunicates use vanadium for something. Life can find a way, once it gets a toehold.

josip

Capt'n Midnight wrote: »

Yes you need a star going through the CNO cycle to make Carbon Nitrogen and Oxygen, and you need that star to go supernova to get those elements expelled from the star.



Silicon dioxide makes up most of the crust of this planet. And most animals and plants ignore silicon. You are most likely to encounter it in the stings of nettles. Similarly Iron , Aluminium and Magnesium make up most of the rest of the crust and again are only used as trace elements. Apart from Oxygen and Hydrogen we only use rare elements from the crust. Calcium we use in bones and things but bacteria don't really need it.

But biological systems are very good at concentrating stuff they do need.

So scarcity of elements isn't a show stopper. And once you leave the top rows of the periodic table elements can substitute to some extent. Arsenic for phosphorous , Strontium for Calcium. We use iron to carry oxygen, other organisms use copper. Tunicates use vanadium for something. Life can find a way, once it gets a toehold.

But they do need toes first?

tac foley

All this thread has provided me with some good reading, but it really poses far more questions than it could possibly answer.

The REAL problem is that our electronic 'message to the stars' is actually getting fainter, rather than stronger, as we use ever shorter wavelength for communication and other electronics prone to atmospheric leakage into space. In the early days of radio, we were happily using huge wave-forms and low frequencies and even TV and RADAR when in their infancy were powerful emitters.

Not so now.

Remember, too, that the shorter wavelengths are more prone to distance attenuation, and as the signal disappears into space it is as much subject to the inverse square law of radio propagation as any other form of electromagnetic radiation. Add to that that we have only been pumping this stuff out for a little over a hundred years, and that alone limits us to a hypothetical hundred light-year sphere of detection.

What is there within that range?

Not a lot, folks.

And even with the latest forms of propulsion, getting to the nearest star would take around 70,000 years, and by the time we got there, the twin stars that make up the Alpha Centauri binary would have moved so that what had been the nearest to us is the furthest away....

Shouting, whether it be with radio or light, is never going to work in our favour - we really are situated in the backwater slums of an average galaxy among a trillion others.

tac

ps200306

Interesting new paper by Sandberg, Drexler, and Ord -- pop science version here, actual paper here. They review various parameters of the Drake Equation, looking at ranges cited in the scientific literature. But their main argument is a mathematical one: estimates of the likelihood of extraterrestrial intelligence are wildly optimistic because of the use of point estimates.

To illustrate the idea, they take a toy model in which the Drake Equation has nine parameters, each with an estimated range of probability from 0 to 20%. The naive approach is to choose a median value of 10% probability for each of the nine parameters, giving a combined probability of one in a billion. With a 100 billion stars in our galaxy, that gives us 100 stars with ETIs. Moreover, the chance that all 100 billion systems come up empty, giving us zero ETIs, is a vanishingly small .

But instead of taking the median probability for each parameter, let's draw them at random from the range 0 - 20%. If we have no other information to guide us this is a better representation of our a priori knowledge. Now the chance that we get an empty galaxy is better than one in five, times more likely than computed with the naive point estimate approach.

Expanding on this line of reasoning with more realistic numbers, they conclude that we shouldn't be surprised to find no intelligent life in our galaxy or even in the observable universe. They are not saying this is likely, just that it is well within the range of probabilities as we know them so far. The "Fermi Paradox" is then not a paradox but merely an observation -- one which serves as disconfirmatory evidence.

Best we don't get off this planet if you ask me. We as a species will sweep through any new planet like a plague, eventually. How long before we're talking about conserving the last few of whatever alien species are left on the new planet? As we've done here. How long til our good intentions turn to "we should dig up every mineral on the new planet for the benefit of business interests?" As we've done here. The rest of the universe will be better off if we live and die on Earth.

In that same vein we might also be better if alien species like ours never make contact.

6541

Sergio Georgini wrote: »

Best we don't get off this planet if you ask me. We as a species will sweep through any new planet like a plague, eventually. How long before we're talking about conserving the last few of whatever alien species are left on the new planet? As we've done here. How long til our good intentions turn to "we should dig up every mineral on the new planet for the benefit of business interests?" As we've done here. The rest of the universe will be better off if we live and die on Earth.

In that same vein we might also be better if alien species like ours never make contact.

The whole point of space exploration is to take more resources, this should be a strategic aim of the human race.

Gwynston

6541 wrote: »

The whole point of space exploration is to take more resources, this should be a strategic aim of the human race.

Well, back at the start, I think it was more about mankind's quest for exploration and achievement. But I agree, in future decades to come it will be more about resources.

But I wonder if that's just inevitable - it is the "survival of the fittest" modus operandi of the human race. It's always been that way - expand in to unexplored territory, consume the resources (even at the expense of the natives), multiply, expand some more. We'll likely try do it in space too before we die out.

As Agent Smith says in The Matrix:

Every mammal on this planet instinctively develops a natural equilibrium with the surrounding environment; but you humans do not. You move to an area and you multiply, and multiply, until every natural resource is consumed and the only way you can survive is to spread to another area. There is another organism on this planet that follows the same pattern. Do you know what it is? A virus. Human beings are a disease, a cancer on this planet, you are a plague

mickmackey1

ps200306 wrote: »

Expanding on this line of reasoning with more realistic numbers, they conclude that we shouldn't be surprised to find no intelligent life in our galaxy or even in the observable universe. They are not saying this is likely, just that it is well within the range of probabilities as we know them so far. The "Fermi Paradox" is then not a paradox but merely an observation -- one which serves as disconfirmatory evidence.

Somewhat related, an article from a synthetic chemist arguing that life really should not exist at all:


http://inference-review.com/article/an-open-letter-to-my-colleagues

Gwynston

mickmackey1 wrote: »

Somewhat related, an article from a synthetic chemist arguing that life really should not exist at all:
http://inference-review.com/article/an-open-letter-to-my-colleagues

That kind of comes across as rather defeatist and really reaches no conclusion:

life based upon amino acids, nucleotides, saccharides and lipids is an anomaly. Life should not exist anywhere in our universe. Life should not even exist on the surface of the earth.

But it does exist! :rolleyes:

The article doesn't so much as conclude that the chemical happenstances which led to life on earth are so unlikely that there's a real possibility we're unique in the universe, but rather seems to say that we are nowhere near to understanding how the chemistry could have happened at all for life to begin, so it simply shouldn't exist and we might as well stick our heads in the sand and not even consider the possibly of it ever happening elsewhere...

Rulmeq

ps200306 wrote: »

With a 100 billion stars in our galaxy, that gives us 100 stars with ETIs.

Out of interest did you take the lowest possible estimate for the number of stars in our galaxy (250billion +/- 150billion), or is that from the article?

mickmackey1

Gwynston wrote: »

:rolleyes:The article doesn't so much as conclude that the chemical happenstances which led to life on earth are so unlikely that there's a real possibility we're unique in the universe, but rather seems to say that we are nowhere near to understanding how the chemistry could have happened at all for life to begin

Well those two viewpoints are connected are they not? We know a lot about spacecraft and supercomputers and atomic weapons, and yet are nowhere near to creating life in the laboratory. This seems to imply that life is fiendishly complex, which jars with its absolute ubiquity in virtually every possible location on Earth. Best to keep an open mind...

Franz Von Peppercorn

Gwynston wrote: »

That kind of comes across as rather defeatist and really reaches no conclusion:

But it does exist! :rolleyes:

The article doesn't so much as conclude that the chemical happenstances which led to life on earth are so unlikely that there's a real possibility we're unique in the universe, but rather seems to say that we are nowhere near to understanding how the chemistry could have happened at all for life to begin, so it simply shouldn't exist and we might as well stick our heads in the sand and not even consider the possibly of it ever happening elsewhere...

That’s precisely what the article was doing.

ps200306

Rulmeq wrote: »

Out of interest did you take the lowest possible estimate for the number of stars in our galaxy (250billion +/- 150billion), or is that from the article?

That's from the paper. They are working in orders of magnitude, so 250 billion vs. 100 billion doesn't even register.

ps200306

mickmackey1 wrote: »

Somewhat related, an article from a synthetic chemist arguing that life really should not exist at all:

http://inference-review.com/article/an-open-letter-to-my-colleagues

An interesting read. In the paper I posted it was also the first time I'd come across the term Levinthal's paradox, though I was aware of the difficulty it describes. Protein folding alone (apart from the other conundrums in your chemistry article) is amazing. After translation, these giant macro-molecules have to fall down an energy gradient undergoing continuous deformation until they arrive at their functional folded form. They coil up into an initial spring called an alpha-helix, and then fold into a complex 3D shape, with correct folding depending on favourable energetics at every step of the process. It's a bit like throwing a large rock down a mountain and watching it bounce it's way to the bottom, only to find it has been battered into a perfect copy of Michelangelo's Pietà.

The difficulty of assigning probabilities to all this stuff is that we have no idea how it started out, and what simpler precursors could have been subsequently shaped by evolution. In Dan Dennett's Darwin's Dangerous Idea (how's that for alliteration!) he uses another analogy of the cathedral dome and arches which couldn't possibly be constructed by simply stacking brick on brick. What we don't see is the supporting scaffolding used in the construction which has long since been removed.

On the other hand, science optimists like Dennett are very good at positing such analogies sans the slightest bit of evidence. He has nothing to go on other than "it must have been this way". At some point we have to come up with plausible pathways or else admit that we will never know. I'm reading a book at the moment called History of Astronomy in the 19th Century, written around 1900. If there's one thing it tells me, it's that scientific speculation -- even the most educated guesses -- are almost invariably wrong to the point of stupidity.

froog

ps200306 wrote:

On the other hand, science optimists like Dennett are very good at positing such analogies sans the slightest bit of evidence. He has nothing to go on other than "it must have been this way". At some point we have to come up with plausible pathways or else admit that we will never know. I'm reading a book at the moment called History of Astronomy in the 19th Century, written around 1900. If there's one thing it tells me, it's that scientific speculation -- even the most educated guesses -- are almost invariably wrong to the point of stupidity.

I've been reading a lot about the RNA world and evolution type mechanisms at work on early organic chemicals. it explains the origin of life quite nicely

ps200306

froog wrote: »

I've been reading a lot about the RNA world and evolution type mechanisms at work on early organic chemicals. it explains the origin of life quite nicely

Too nicely maybe? Even allowing for auto-catalysis to do away with a lot of transcription machinery, isn't the simplest RNA frighteningly complex too? Or does it give some other insights?

Capt'n Midnight

Sergio Georgini wrote: »

Best we don't get off this planet if you ask me. We as a species will sweep through any new planet like a plague, eventually. How long before we're talking about conserving the last few of whatever alien species are left on the new planet? As we've done here. How long til our good intentions turn to "we should dig up every mineral on the new planet for the benefit of business interests?" As we've done here. The rest of the universe will be better off if we live and die on Earth.

In that same vein we might also be better if alien species like ours never make contact.

One big impact or close supernova and all known life is gone forever ?

Even a minor impact, or nuclear war, or grey goo, or mutated flu or any number of things on the risk list would wipe out intelligent life that could mitigate the next big event.


We need a Plan B


But there's no point in going to other planets for resources. They are at the bottom of a gravity well. More trouble than it's worth. Far more accessible materials amongst the asteroids and lots more living space.

Mars gets 40% of sunlight that earth does, when there aren't month long dust storms. But near the asteroids you have sunlight 24/7 and with enough energy you can extract carbon and iron and aluminium, platnium if you get lucky.

mickmackey1

ps200306 wrote: »

Dan Dennett's Darwin's Dangerous Idea (how's that for alliteration!)

Preferred the sequel, Darwin's Dangerous Deduction :pac:

froog wrote: »

I've been reading a lot about the RNA world and evolution type mechanisms at work on early organic chemicals. it explains the origin of life quite nicely

The Nobel committee are waiting to hear from you.

dr.fuzzenstein

Imagine you're an alien and you're orbiting Earth.
You'd have the ability to intercept radiowaves and you have access to the internet.
If I was that alien I would not make contact.
Too hostile, primitive and violent.
Aliens would either not make contact at all or would arrive with a large invasion fleet.
Why? Because human history is one of conquest. We don't explore just because we want to see what's behind the next hill. But also because we hope that there are other people living there who managed to build up something by their hard work and determination. So that we can conquer them and steal their stuff.
Once humans would know that there are advanced civilisations out there, we would immediately have one thought. How can we outgun them. And if they have oil, the US would be out there with warships like a shot.
We are the evil and aggressive aliens. If we are friendly, it's because we don't have the power to overcome someone. Once we have that power, we can't be trusted.
As an alien race to contact, we are too primitive, violent, greedy and selfish. For now we stay put on our planet because we don't know that there's anyone out there. If we knew, we'd be working ten times as hard on our space travel. Aliens don't contact us because right now we're staying put and are no threat.
It's not just about intelligence, but about moral and emotional maturity. And from that standpoint we are too close to apes. Friendly, but can turn vicious and violent in a second.
Untrustworthy.

Wibbs

dr.fuzzenstein wrote: »

It's not just about intelligence, but about moral and emotional maturity. And from that standpoint we are too close to apes. Friendly, but can turn vicious and violent in a second.
Untrustworthy.

Meh, I dunno. That's more a recent viewpoint on humanity. Go back a couple of centuries and we saw ourselves as flawed, but top of the tree beings, just below whatever gods were around. This "sure humans are little more than violent apes" was part of the backlash to earlier religious and philosophical thought. It would also be very common in mainstream science fiction.

I would contend we're somewhere in the middle, but minus the god bits, closer to the older more hopeful view. History bears this out as much as it bears out our "killer ape" label. Human history has with a few glitches along the way been an ever increasing drive towards more comfort, fairness and better lives for societies and individuals. You live a life of more comfort, access to better health and knowledge that the greatest pharaohs of Egypt could only dream of.

Plus if any possible aliens could travel to our world from theirs their technology would be so far advanced of ours that it wouldn't matter how warlike or otherwise we were. They could wipe us out in days if not hours(and likely be able to leave the planet otherwise unharmed). It would be similar to a fully tooled up special forces platoon descending on a stone aged tribe in the depths of New Guinea. With drones. We'd be of almost zero threat to such a species that could star travel. They might not even take much notice of us, beyond maybe some curiosity about these little things running around.

M.T. Cranium

It does seem very unlikely to me that advanced civilizations of intelligent aliens could exist within our galaxy yet avoid any contact with us over the entire span of our recorded history. Of course, many believe that certain evidence exists, but it's fair to say that the scientific consensus (as opposed to public opinion) maintains that no contact has been proven.

So that leaves us with two plausible reasons for no contact -- (a) there is nothing out there to contact us, or (b) whatever does exist has either independently or collaboratively decided to prevent contact. That seems rather time consuming, they would have to disguise their communications across the galaxy, and to do that, they would have needed to know of our existence at a very early stage or even before humanity evolved (or was created if you prefer). That just makes them more frighteningly intelligent and points to a role in our creation possibly (you can go the managed evolution route if you prefer).

I have used the term "galaxy" here because I suppose it would be much more difficult for us to detect signs of intelligent life in some other galaxy. So there could be a hypothesis where, let's say, Andromeda galaxy was teeming with intelligent life forms who had never been this far from home.

My conclusion is that the answer is (b), they exist and are well organized enough to avoid detection or contact. Their reasons for this must be altruistic since almost every scenario in which they materialize in our midst seems unlikely to bring much good for us, especially if we are the other white meat for them.

M.T. Cranium

David Icke says they are here and running the show. I met him in person once (due to a legal case where he was a witness) and I had a chance to ask him, "do you really believe in that theory, or is it just a way of saying that our global elites have reptilian characteristics on a spiritual level, while actually being just as human as us?"

He gave me that look to say, "you must be one of them to have thought of that," and then just said no, he believed it literally.

I don't, but one or two could have been here in disguise from time to time then left with reports for the home base, I mean why not, how could we ever disprove that?

Wibbs

The problem with Fermi's hypothesis and any others for that matter is they're all at best beautifully formed conjecture. We quite simply don't know how easy or difficult it is for life to start. We have an example of one and that can't tell you much of anything, beyond well it happened here.

And yes it did happen here, but it seems it happened "the once". All life on this planet is related however distantly. So even this world which it seems was ideal for life only got one version off the ground.

Secondly that life for the majority of earth's history was very basic, single celled with a few clumping together for fun and it stayed that way for billions of years happy out. Complex life came along in a sudden burst in the late precambrian for reasons that aren't quite clear. And when it did it took the guts of another billion years for intelligent life to come along. Then there were a few global extinction events that cleared the decks and that could have gone either way so very easily. If the dinosaurs hadn't gone its unlikely the mammals would have risen and us with them.

Pretty much every other evolutionary killer app has come along multiple times in multiple species. Flight, Swimming etc. But intelligence not so much. Yes there are intelligent animals of course, but our particular type of intelligence is incredibly rare and only found in us. Hell, earlier humans didn't have it to the degree that we do. If modern humans hadn't evolved in Africa or had been wiped out by a local extinction event(which very nearly happened) then our world today would be very sparsely populated in temperate areas by small bands of intelligent for great apes hominid predators doing fine thanks very much, but having little impact on the world and certainly not capable of asking questions like this.

Even if we do find another world with life and it's basically goo, then that might suggest life kicks off handily enough, but it doesn't tell us how easily complex life kicks off, or common it might be and it certainly doesn't tell us how likely intelligent life of our sort is. Again in our only example our arrival was a complete fluke with many many fathers along the way.

Wibbs

M.T. Cranium wrote: »

It does seem very unlikely to me that advanced civilizations of intelligent aliens could exist within our galaxy yet avoid any contact with us over the entire span of our recorded history.

Maybe they never bother? There could well be an type of intelligence as different ours as ours is from Homo Erectus and that particular type of intelligence may not be curious, or lose that curiosity over time. Another possibility is that their virtual world building gets so good, down to quantum information level simulation, that they retreat within it and explore that. Within such a simulation they could "visit" other worlds and "time travel" too, without all the pesky realities in the real universe. If they figured out how brains perceive time they could also live several lifetimes within such a simulation. Or the simulations get so good that the original inventors eventually die off and go extinct and the simulation runs itself. Within such a scenario simulated beings may not even know they are simulated. How do you know you're "real" and more, how do you know I am? Such a civilisation would be nigh on invisible to outside viewers.

Time is another aspect. Imagine the universe as a large valley at night. You're living in your cabin, but you don't know if other cabins exist out there. You're legs aren't the best so you can only slowly walk to your small garden's gate. You invent a lamp to read and you look out your window and can't see any other lamps, so you figure there aren't any other cabins. You would only realise there were if someone in another cabin invented a lamp at around the same time as you and you both were looking in the right direction. There could be hundreds of people in hundreds of lamp free cabins in the dark valley. Others may have gone beyond the lamps and are playing on their xbox with the blinds drawn. Some may yet to be born into the cabin, others may have died and are bones. Now imagine that valley over billions of years and over millions of lightyears.

Humanity has had radio for little over a century, the electric light similarly. A passing alien probe through our solar system even as recently as the 1600's would have had to slow right down and watch our world very closely to spot us. Passing through in the 1950s it would have picked up radio transmissions, but more and more we're using radio less and our radio leaky world is ever less leaky. In a century's time or many century's time, we may be even more "silent". To be fair any alien probe would likely spot our little blue world as a standout and would approach, but in our world's billions year history down to today it would have to be traveling by within a window of about twenty odd thousand years to see the potential of us and we could be gone in another twenty odd thousand years, or less. That's one needle in one haystack across thousands of acres of haystacks.

So I would say the best philosophical approach to take is to keep our minds open, but for the moment work on the principle that we are indeed alone and that nobody out there is coming to kill us, or more, nobody out there is coming to save us and we need to save ourselves and that most importantly of all, we're worth saving. If we do save ourselves we may one day become those beneficent aliens that could save others, even the universe itself.

Gwynston

dr.fuzzenstein wrote: »

Aliens don't contact us because right now we're staying put and are no threat.
It's not just about intelligence, but about moral and emotional maturity. And from that standpoint we are too close to apes. Friendly, but can turn vicious and violent in a second.

How can we be so sure that vastly intelligent aliens capable of visiting us would only be considering doing so for the mutual benefit of species-kind? It's not a given that higher intelligence goes together with better morals and compassion.

What if our history of conquest and assimilation is merely the ultimate extension of "survival of the fittest"? The history of life is full of examples of species which flourish at the expense of others. Maybe that's how life is "supposed" to work, not through compassion and empathy. Maybe conquest is ultimately how intelligence advances?

If so, aliens visiting earth could well do it just for conquest. Being more advanced and intelligent doesn't preclude that as an aim.

tac foley

I've made the point a number of times that our electronic transmissions are actually getting less and less as we move inexorably into the widespread use of microwave communications. Using the inverse square law of radio propagation as the ruling limitation, our rapidly diminishing use of long-wave radio, used for comms between the GS and distant objects like Voyager, are now almost undetectable by the very object that needs them, AND it has barely left the solar system, let alone travelled a single light year.

As for TV, the use of digital date transmission is limiting the envelope to the sphere on which we live. The use of LASERs as comms is the way ahead, but then again, it has to be aimed, or at least detectable at long range. All EM is subject to the limitations of the same velocity, namely 300 kps/186,000 mph - until we invent the here/there it is transmission sysyem, it is the limits of physics - universal constants - that defeat us.

tac