A universe full of dead aliens

Gwynston

hgfj wrote: »

Personally, I love the idea of an advanced alien civilisation zipping about the universe at warp speed in and out of wormholes exploring new planets and whatnot, and all the while scratching their heads saying, "Okay, we know this and we know that, we understand this and we understand that but what does it all mean?"

Well obviously the answer is 42.
All they need now is to find Earth to work out what the question means! :P
(Before it gets destroyed prematurely...)

Stuxnet

"Earth's broadcasts reach only about 80 light-years into space. If humanity is average, then other civilizations would have reached a similar distance, covering less than a tenth of 1 percent of the Milky Way."

We may have to wait 1500 years lads to hear anything !!

http://www.space.com/33203-aliens-extraterrestrial-life-1500-years-for-contact.html

qrx

Stuxnet wrote: »

"Earth's broadcasts reach only about 80 light-years into space. If humanity is average, then other civilizations would have reached a similar distance, covering less than a tenth of 1 percent of the Milky Way."

We may have to wait 1500 years lads to hear anything !!

http://www.space.com/33203-aliens-extraterrestrial-life-1500-years-for-contact.html

And seeing as the first broadcasts they'll see are the Nazis, chances are they'll want to avoid us.

Gwynston

qrx wrote: »

And seeing as the first broadcasts they'll see are the Nazis, chances are they'll want to avoid us.

To be fair, I don't think the Nazis broadcast much of the bad stuff they were doing. Their early powerful broadcasts were all populist propaganda, so aliens viewing them might actually be impressed by such a well-ordered and well-behaved civilisation...

ThunderCat

I'm not sure contact is necessary on the part of a species far more technologically advanced than us. If they have the means to travel between the stars then they are advanced enough to send microscopic probes undetectable to us to Earth to observe what life is like here.

PMBC

What is the current thinking on the 'Drake Equation' which estimated the chance of more life forms in the Universe - I think it didn't allow for stages of development/evolution i.e. that life forms might be at single cell or other early status?

Gwynston

Yes, the Drake equation does include something for that:
https://en.wikipedia.org/wiki/Drake_equation

L = the length of time for which such civilizations release detectable signals into space

The trouble with the the Drake question though is that the result varies hugely with a small change of any one of the factors.

So what might seem like logical values can produce promising results, but a reasonable small tweek to one parameter up or down to see what variation it causes, ends up with something wildly different and a supposedly unrelated answer. In practice this means the input values can be subconsciously fiddled in order to produce a pre-conceived desired outcome.

It is useful in helping to understand the factors that inevitably affect the possibility of there being other intelligent life out there. But it's no good at giving an accurate answer as most of the inputs are wild guesses!

qrx

Gwynston wrote: »

Yes, the Drake equation does include something for that:
https://en.wikipedia.org/wiki/Drake_equation


The trouble with the the Drake question though is that the result varies hugely with a small change of any one of the factors.

So what might seem like logical values can produce promising results, but a reasonable small tweek to one parameter up or down to see what variation it causes, ends up with something wildly different and a supposedly unrelated answer. In practice this means the input values can be subconsciously fiddled in order to produce a pre-conceived desired outcome.

It is useful in helping to understand the factors that inevitably affect the possibility of there being other intelligent life out there. But it's no good at giving an accurate answer as most of the inputs are wild guesses!

If seti detects your post it'll be another Wow moment.

mickmackey1

What I don't often see discussed is that aliens could be in the same boat as us... even if they are a million years ahead of humans they could be a million years behind other aliens. So they cannot embark on galactic voyages because of the superior technology they might encounter. Which could be a possible solution to the Fermi paradox.

ps200306

I didn't find the paper referenced from the article in the OP all that compelling. First of all, the idea that there is no stable circumstellar habitable zone, and that life must evolve fast enough to make the biosphere self-regulating... how can we possibly have any idea of the likelihood of that? Isn't is just as likely that a planet will push itself out of the CHZ on the way to self-regulation? For instance, imagine a four billion year old Mars with a thick CO2 atmosphere and liquid water. If photosynthesis evolves and floods the atmosphere with oxygen, it probably pushes Mars over the age so that the water freezes, the atmosphere thins and gets lost over time due to lower gravity. The point is Mars was close to the edge to begin with.

Was it inevitable that earth would evolve toward a self-regulating competition between respiration and photosynthesis? The oxygen would initially have been a poisonous waste product. How important, and how common, is the percentage of metallic iron that we have in the planet's crust? It kept the oxygen levels down for a billion years until the surface had literally rusted. How self-regulating was the resulting system anyway? We seem to have had a high-oxygen period during the Carboniferous when a lot of plant life died and was buried in an anoxic environment, giving rise to the buried hydrocarbons that we are unleashing today. Giant insects preserved in amber from the period suggest that oxygen levels were several percent above present day levels. Could we survive today at that level?

The problem is there are so many contingencies and what-ifs with poorly understood answers that it's hard to say anything reliably. The only definite fact is that the universe is not teeming with advanced life anxious to talk to us. It might be dead, or we might be too dumb, who knows. The naive version of the Drake equation certainly seems to have some holes in it, just as we are discovering that exoplanets are as common as muck.

Gwynston

ps200306 wrote: »

Isn't is just as likely that a planet will push itself out of the CHZ on the way to self-regulation?

Well yes, of course. There are way more possible uninhabitable outcomes than habitable ones. It just so happens that we ended up in one that worked out, so we're in the position try to look back time and speculate what happened. Obviously there's no-one on all the dead planets that didn't work out habitable to compare with.

But that's not to say that out of the billions of planets in the galaxy, a few couldn't have followed a self-regulating biosphere kind of model.

ps200306

Gwynston wrote: »

But that's not to say that out of the billions of planets in the galaxy, a few couldn't have followed a self-regulating biosphere kind of model.

The problem with all such speculation is that we need the number to be very low in order to explain the apparent absence of visitations, but perhaps not so low as to make the Earth unique. But whether the number is singular or merely tiny, there is a worrying whiff of fine tuning to whittle the number down from the billions of rocky planets that we now know exist.

Smiles35

According to the SETI people the search for radio hasn't really begun yet. A Russion billionare threw 100mil at them recently.

I'm convinced we will get one or two 'hits' in the next few years.

Gwynston

In the wake of the discovery of a planet around Proxima Centauri, this BBC article discusses at a high level some of the factors other than the Goldilocks Zone which affect habitability:

Where should we look for alien life?

_Tombstone_

​What If We Haven’t Found Aliens Because Humans Came First?

http://motherboard.vice.com/read/what-if-we-havent-found-aliens-because-humans-came-first.

Capt'n Midnight

PMBC wrote: »

What is the current thinking on the 'Drake Equation' which estimated the chance of more life forms in the Universe - I think it didn't allow for stages of development/evolution i.e. that life forms might be at single cell or other early status?

IMHO the Fermi paradox counters it.

And yes the Drake equation had terms for going from life to intelligent life and then to intelligent life that sends signals and for how long that intelligent life would do so.

We have already stopped sending intelligible signals into space. Almost everything is digital, with focused beams and the signal to noise margins are pared right back, and even then most of it is encrypted. Shannon's Law means that ET how has much chance of deciphering our signals as you'd have picking up SaorSat in London.

High power radio is going too, the MW band is practically empty during the day and LW is heading that way.

The big spikes are now 50Hz/60Hz mains and 3GHz radar. The former contains no info and could be explained away as something physical, the latter isn't synchronised and will fade slowly with more GPS and better receivers.

Maximus Alexander

Capt'n Midnight wrote: »

IMHO the Fermi paradox counters it.

And yes the Drake equation had terms for going from life to intelligent life and then to intelligent life that sends signals and for how long that intelligent life would do so.

We have already stopped sending intelligible signals into space. Almost everything is digital, with focused beams and the signal to noise margins are pared right back, and even then most of it is encrypted. Shannon's Law means that ET how has much chance of deciphering our signals as you'd have picking up SaorSat in London.

High power radio is going too, the MW band is practically empty during the day and LW is heading that way.

The big spikes are now 50Hz/60Hz mains and 3GHz radar. The former contains no info and could be explained away as something physical, the latter isn't synchronised and will fade slowly with more GPS and better receivers.

In fairness, you don't need to be able to decipher them in order to identify them as artificial, which is the key thing really. The rest is true though, so it's moot. The encrypted signals won't be going anywhere for ET to detect them.

ps200306

_Tombstone_ wrote: »

​What If We Haven’t Found Aliens Because Humans Came First?

http://motherboard.vice.com/read/what-if-we-havent-found-aliens-because-humans-came-first.

The problem with that, it seems to me, is that if something is astonishingly, unbelievably unlikely -- so unlikely that it hasn't happened in all the hundreds of billions of stars and planets of our galaxy and the countless trillions in others -- then stripping a few zeros out of the 0.0000...001% probability still leaves it very improbable.

Likewise, if something is overwhelmingly likely, so likely that trimming a few nines off the end of 99.999999...% makes no difference, then it is still very likely.

The universe is old enough to have had generations of G type stars like ours. Even trimming off lots of time to allow for the galaxies to be enriched with lots of heavy elements from supernova explosions, there have still been billions of years of evolution of countless suitable stars. M type dwarfs may well last three orders of magnitude longer than our Sun, perhaps even more, but three orders of magnitude doesn't seem all that much when amplifying an exceedingly tiny probability, or attenuating an exceedingly large one.

To my mind that would still either leave the Earth in a quite unique position, forcing us to rethink the Copernican Principle, or it would imply an oddly finely balanced probability of (intelligent) life ... neither very probable nor very improbable in spite of the countless numbers of similar locations in which it could get going. Add to this the observation that some sort of life got going on Earth almost as soon as physically possible, and it suggests even stranger probabilities for intelligence.

PMBC

Would we have eveloved if the dinos had not been wiped out? Was that event not very small statistically?

Maximus Alexander

PMBC wrote: »

Would we have eveloved if the dinos had not been wiped out? Was that event not very small statistically?

It's impossible to know what direction life on Earth would have taken if the dinosaurs weren't wiped out, but mass extinction events like the one that wiped them out have been pretty regular over geological time scales.

seamus

It is worth noting that larger dinosaurs had been on a decline for millions of years before the K-T event. It's pretty likely that without it the large non-avian dinosaurs would have become extinct naturally. The changing global climate was better suited to the small feathered flyers than the classic terrible lizards. Would mammals still have dominated? Very hard to say. Large swathes of life from all kingdoms were wiped out in the K-T event, mammals just had that slight edge.

The intelligence levels of many birds tells us that human-level intelligence is not necessarily limited to strict and specific circumstances, but could arise at any time really.

We also don't know if sentient intelligence never existed on earth before. If a meteor event like K-T were to happen again tomorrow, any civilisation that appeared 66 million years from now would likely know nothing of our existence, all of our structures crumbled and blown away, all evidence of our existence having been wiped out by the geological timescale.
So perhaps some evidence might exist - like the odd satellite or buried nuclear waste. But if we had been wiped out in the 1800s, humanity's existence would never be known about.
So we actually can't assume that an intelligent civilisation has never existed on earth before.

Maximus Alexander

seamus wrote: »

We also don't know if sentient intelligence never existed on earth before. If a meteor event like K-T were to happen again tomorrow, any civilisation that appeared 66 million years from now would likely know nothing of our existence, all of our structures crumbled and blown away, all evidence of our existence having been wiped out by the geological timescale.
So perhaps some evidence might exist - like the odd satellite or buried nuclear waste. But if we had been wiped out in the 1800s, humanity's existence would never be known about.
So we actually can't assume that an intelligent civilisation has never existed on earth before.

Interesting perspective. I'd say it's safe enough to rule out a technological species because you would expect there would be clues about their tools and machines in the fossil record. However, it would probably be hard to rule our something more akin to early man in the cave painting phase having existed 10s of millions of years ago. Never really thought about it like that before.

seamus

Even on the simplest scale thinking about human evolution and the patchiness of our own fossil record; for some species we have only part of a single individual as confirmation that an intelligent species (and society) ever existed. How many evolutionary dead-ends (like Neanderthals) occurred in the homind tree that we will never know about? But nonetheless were likely to be intelligent species.

And considering that these species existed yesterday in geological terms, it's quite possible that hundreds of distinct species with human-level intelligence could have evolved and died in the last 500 million years, and we'd never know.

PMBC

Thanks Max and Seamus.
I didn't appreciate how frequent such meteor strikes were or that the large dinos were already on the wane. I don't have any 'position' on intelligent design versus chance except one of constantly wondering.

Capt'n Midnight

PMBC wrote: »

Would we have eveloved if the dinos had not been wiped out? Was that event not very small statistically?

Perhaps. But very unlikely. The ancestors of mammals split from the ancestors of the dino's about 275 million years ago. So we had 210 million years to make it to the top before the dinos died out. Birds took over for a while.



As for intelligent dino's winning out ?

Comparing brain sizes even the smartest dinos don't compare well to dumb birds. So any surviving species could have won the brains race. Birds, other dinos, mammals, other mammals, other reptiles, whatever.

Note that if the dinos had survived and become intelligent then they would not look like us despite all the bad SciFi. The only excuse for saying so is to save money on costumes and that's no longer a good excuse given how cheap computer graphics are these days.


Just look at the other candidates for intelligent life here. Most are quadrupeds with tails. The bipeds have wings. Dolphins don't have legs.

And they all very similar to us compared to an octopus. And even they shared a common ancestor for most of the time life existed on this planet. So apart from streamlining don't expect ET look like anything us.

ps200306

_Tombstone_ wrote: »

​What If We Haven’t Found Aliens Because Humans Came First?

http://motherboard.vice.com/read/what-if-we-havent-found-aliens-because-humans-came-first.

Sorry for quoting your post a second time but something else just occurred to me about it. Red dwarf stars may last thousands of times longer than our Sun, but their planets may not last that long in a habitable state. I'm thinking in particular of plate tectonics. Won't all mantle activity in a rocky planet have ceased long, long before trillions of years have elapsed?

We can't be certain how vital plate tectonics is, but it seems to have played a major role in regulating our atmosphere through volcanoes and mountain weathering, altering mantle chemistry with subducted water, concentrating vital mineral veins, making fertile land, creating environments for allopatric speciation, and perhaps a host of other things we don't know about.

Planets vastly older than our own might not then be such good candidates for life.

Capt'n Midnight

ps200306 wrote: »

We can't be certain how vital plate tectonics is, but it seems to have played a major role in regulating our atmosphere through volcanoes and mountain weathering, altering mantle chemistry with subducted water, concentrating vital mineral veins, making fertile land, creating environments for allopatric speciation, and perhaps a host of other things we don't know about.

Overall solar wind would be worse from a red dwarf ?

Other than that lower temperature star would mean less photo-dissociation ? so maybe a longer lasting atmosphere, or at least more able to support an atmosphere with lower gravity. So would make it easier for the inhabitants to leave the planet. most photosynthesis here uses red light anyway.

ps200306

Yes, worse solar wind. And a planet in the habitable zone after star formation would apparently be in a pretty hot zone for an extended period before an M dwarf reaches the main sequence. Photo-dissociation of the water with all the hydrogen escaping could leave only oxygen.

Taking this from a Wikipedia page I hadn't realised existed: Habitability of red dwarf systems

Another good article: Red Dwarf Planets Face Hostile Space Weather Within Habitable Zone/

It all sounds a bit bleak.

froog

regarding the possibility of intelligent life in the galaxy (or universe) i like to think of it this way - in the absolutely miniscule sample size of space we have explored and the handful of planets we've seen up close out of many many billions, we have absolute proof of one intelligent civilization - us.

Chromosphere

Considering we're only 50 years, if even into the level of technology to detect anything, I think we're still not really able to conclude anything other than we haven't found anything yet.

For all we know we may have stumbled upon radio waves, while others have stumbled upon something fundamental that we haven't hit upon yet and we are not actively detecting.

We should definitely keep looking though. We've only barely scratched the surface.