The aliens are silent because they're dead

[FLPanhandle]

http://phys.org/news/2016-01-aliens-silent-theyre-dead.html



Life on other planets would likely be brief and become extinct very quickly, say astrobiologists from The Australian National University (ANU).

In research aiming to understand how life might develop, the scientists realised new life would commonly die out due to runaway heating or cooling on their fledgling planets.

"The universe is probably filled with habitable planets, so many scientists think it should be teeming with aliens," said Dr Aditya Chopra from the ANU Research School of Earth Sciences and lead author on the paper, which is published in Astrobiology.

"Early life is fragile, so we believe it rarely evolves quickly enough to survive."

"Most early planetary environments are unstable. To produce a habitable planet, life forms need to regulate greenhouse gases such as water and carbon dioxide to keep surface temperatures stable."

About four billion years ago Earth, Venus and Mars may have all been habitable. However, a billion years or so after formation, Venus turned into a hothouse and Mars froze into an icebox.

Early microbial life on Venus and Mars, if there was any, failed to stabilise the rapidly changing environment, said co-author Associate Professor Charley Lineweaver from the ANU Planetary Science Institute.

"Life on Earth probably played a leading role in stabilising the planet's climate," he said.

Dr Chopra said their theory solved a puzzle.

"The mystery of why we haven't yet found signs of aliens may have less to do with the likelihood of the origin of life or intelligence and have more to do with the rarity of the rapid emergence of biological regulation of feedback cycles on planetary surfaces," he said.

Wet, rocky planets, with the ingredients and energy sources required for life seem to be ubiquitous, however, as physicist Enrico Fermi pointed out in 1950, no signs of surviving extra-terrestrial life have been found.

A plausible solution to Fermi's paradox, say the researchers, is near universal early extinction, which they have named the Gaian Bottleneck.


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Even if they did survive, it was probably for a short window.

[B Calm]

1. Ted Cruz died?

[lumberjack_jeff]

2. I recommend the book "Rare Earth" nt

[exboyfil]

4. Great Book

I read it about five years ago. The more we learn about biology and the history of our planet, the more I agree with the assessment that technological life is extremely rare (so rare that at any one time you might expect 1 or fewer species in a galaxy).

The number of snow ball Earth events we went through is just one example. No reason to think that we would ever have recovered from them. Not to mention asteroid impacts, gamma ray bursts, etc.

Also how long was complex life on Earth with no demonstrated ability for complex tool use.

[Johonny]

22. Great Book. Peter Ward puts together good books.

[lovemydog]

36. Pretty good band too.

[hatrack]

48. Superb book

Also the guy who wrote "Gorgon" and "Under A Green Sky", IIRC.

[roguevalley]

57. I love how scientists assume that all life is needful of the

same things and that if they aren't there no life exists or whatever. I think the universe is way more complex and diverse than that.

[physioex]

3. Maybe..Maybe Not....

This simply refers to life in the 'carbon' DNA based sense. Who is to say that civilization based on carbon could not produce an offspring of machine intelligence based on silicon? And why would that civilization need the same type of 'habitable planet' like ones based on carbon?

[exboyfil]

6. It is even getting to the technological state that is the question

As you state at a certain point a civilization could be considered eternal (or at least until the heat death of the universe). Once self replicating probes/AI robots reach other star systems, then the odds go up tremendously.

We used up over half the life of our sun getting to this point passing through many keyhole events for complex life, hominids, and humans.

[longship]

5. This absolute rubbish.

The reason why SETI has not discovered any life is simple. (Okham's razor!)

1. The galaxy is really, really big. Distances between stars is (as Donald Trump might say) huge.

2. As Jill Tartar has often stated, we have only dipped into the ocean with a couple glass fulls to see if there is other life. (Yes, it's not a perfect metaphor, but one can get the idea that there would not likely be any fish in those couple of glass fulls, which is her point.)

3. One has to reject the "rare Earth" hypothesis outright simply because it is, by definition, biased upon a single data point.

4. Does anybody credibly think that life does not exist on other worlds? No! Then just given the number of stars in the galaxy, all which likely have planets, there must be a multitude of planets with life, and many with intelligent life.

5. Fermi paradox is a non-starter. "Where are they? Why haven't they visited us?" Well, Enrico Fermi should have known the answer to this. Space is really, really large. Distances between worlds with intelligent life is really, really large even if it is plentiful. And interstellar travel is fucking expensive in resources -- really, really fucking expensive. It would not be surprising if nobody does it.

6. My favorite explanation, from mathematician Ian Stewart and biologist Jack Cohen: maybe they are all just listening and waiting, asking the same questions as Fermi did, but doing nothing about it. That especially knowing how difficult a proposition interstellar travel is.

[exboyfil]

8. I agree that we have insufficiently looked

to exclude the possibility of technological life. On the other hand, like in the book Rare Earth, if you start from the bottom up you begin to understand the hurdles associated with achieving technological life in our galaxy (for all intents and purposes other galaxies are off the table because of the distances involved).

On 4 most scientists would agree that there is a high probability of life on other planets in the galaxy currently (approaching 1). Multicellular eukaryote along the line of protists or fungi probably a 0.9. Something like an animal on the other hand - the first sponge took 3 B years to evolve. It still took 500 M years after the Cambrian explosion to evolve a species capable of manipulating technology.

These time frames are on the order of a 1/2 life of stars like our Sun. Red dwarves which last on the order of a trillion years have their own issues for the development of life (tidal heating and frequent flaring for example).

Maybe their are other paths towards technological life that we do not yet understand.

In any event we have to keep looking and exploring.

[longship]

14. On Rare Earth.

I really like Peter Ward, but he's full of shit on this. He should stick to paleontology, which I understand he is now doing in Australia which a great place to do such a thing. However, his rare Earth arguments resemble those of intelligent design. Plus, his argument is from a single data point.

[Rex]

9. Great points!

We've only surveyed a fraction of the known universe! Space-time is 'too big to imagine' big, so contact might never happen.

[Whiskeytide]

17. Interstellar travel IS very expensive in terms of resources...

... that's why we can be sure John Travolta and Forrest Whitaker are coming to get ours!

[longship]

19. Xenu!!!!!!!

Like the South Park episode.

Red text at the bottom of the screen. "Scientologists really believe this."

And the entire credits for that episode are anonymous.

One of the best! (Also, John Edward is the biggest douche in the universe.)

[lumberjack_jeff]

21. The universe is big, but it is also old.

If you're right, humans should have evolved while standing knee deep in alien robotic artifacts.

In 100 years we will have sent probes throughout the solar system. In 1000 years we will have sent autonomous self-repairing probes throughout this part of the galaxy. All this in about 10k years of human evolution.

The galaxy is old enough to have done this fifteen million times, even if one assumes only one civilization at a time.

Yet every time a human set foot somewhere, he or she discovered it.

The only boot prints any place in this solar system fit humans.

Fermi was right.

[longship]

28. Yes, you are correct. Time is long.

However, how long does intelligent life last. If it is not long, than it is possible than few planets have intelligent life at one time, which means the distance would be greater.

And likewise, I reject your knee deep argument even if intelligent lifetime is long merely because distances between stars are just so great and interstellar travel is that fucking difficult. And there are not likely any warp drives to help.

Yes, I understand the specifics of Fermi's argument, especially the long time parameter. I also understand what it would take to launch a probe to another star. We actually have five on the way out there, none of which will live long enough to get to even the closest star.

Nevertheless, this is interesting stuff to consider.

[lumberjack_jeff]

38. If autonomous self-repairing probes are possible...

... and intelligent life is anything other than extremely rare, then the knee deep argument is not only valid, but compelling, because long distances are immaterial to machines.

I think the implication of Rare Earth is a powerful responsibility to take care of life on this planet long enough that WE can spread it elsewhere.

[longship]

39. Yes, and if my grandmother had wheels she'd be a wagon.

Homage to Montgomery Scott.

[lumberjack_jeff]

40. It may someday be possible to equip the wagon with wings and grandma's consciousness. n/t

[longship]

42. Ah yes! The Ray Kurzweil solution.

A Matrix wet dream.

[sibelian]

33. There's a whole hyoooooge pile of unexamined assumptions that lead to the Fermi "Paradox"...

...None of which are particularly related, per se, to the actual propensity of the Universe to produce intelligent forms at all, which is a different question. Suppose there really is ubiquitous Non-Terran Intelligence. In order for Fermi's question not to look silly a whole bunch of things about them have to be "obvious", for example:

1. Non-Terran Intelligence will be organised in social clusters large enough to support space travel
2. Non-Terran Intelligence will use tools that focus on travel
3. Non Terran Intelligence will use tools at all
4. Non-Terran Intelligence will use those tools for the construction of the kind of technologically advanced civilisation that could fund and develop space travel rather than simply using it for the betterment of smaller distinct communities
5. Non-Terran Intelligence will find an energy source that's sufficiently cheap and reliably acquirable that a technologically based civilisation capable of space travel will be able to emerge
6. (Probably not so significant on the wet rockies, but...) Non-Terran Intelligence will develop on planets that are NOT permanently overcast so that they can actually tell they're part of a wider system than their own planet (I have no problem with the idea that an alien civilisation could conceivably get as far as fission reactors without knowing they even have a SUN... Imagine an advanced civilisation developing under the ice on Europa, we might expect amazing poetry, beautiful architecture, incredible materials science and no understanding of orbital mechanics of any... kind...)
7. Non-Terran Intelligence will have eyes, meaning that they will see the sky, and that they are part of a wider system than their own planet.
8. Non-Terran Intelligence will have a natural curiosity about astronomical phenomena leading to the development of astronomy.
9. Non-Terran Intelligence will have a nice friendly moon just nearby that can easily be explored (once all the other skittles have been knocked over) as part of a historical narrative encouraging them to think space travel is worth something, and also a nice friendly planet slightly further away as a "next step" whose gravity is reasonably tolerable to the Non-Terran intelligences...

And so on. It's not just life on Earth that's a single data point, as you very sensibly indicate, in fact every single step in the human achievement of space-faring capability is also a single data point.

[Avalux]

7. Dr Aditya Chopra seems to have the universe all figured out.

It's foolish to assume that 'life' existing outside of earth would follow the same paradigm as life does here. It's foolish to think just because we haven't seen it, it doesn't exist. We simply do not know, there is so much out there we can't explain.

For example, we think we just found a planet the size of Neptune within our solar system. That's our backyard and we didn't know it was there.

[Rex]

10. There could be a rogue sun out there somewhere too.

I don't know how much stock to put in it, but some say there is a Red Dwarf way way WAY out there orbiting the sun called Nemesis that is responsible for many extinction events as it travels once every 26 million years around our known sun!

[longship]

29. We have pretty damned good telescopes.

And we know of lots and lots of M-dwarfs. After all, over 75% of stars are of that class. Our surveys of the sky show no such Nemesis. It is reasonable to state that such a thing is highly unlikely or it would have already been discovered.

And we have some really, really good sky surveys these days.

[Rex]

44. I agree, only read about it just this past month.

Small red dwarf, I think they were linking it in with the extinction of the dinosaurs. Still an interesting theory, but I would think we would detect something like a red dwarf that is close by.

[longship]

45. There are no red dwarfs closer than Alpha Centauri.

None! And we would have known about any decades, probably centuries ago.

They might not be very bright, but if one were close, we'd damn well know about it.

[Rex]

46. That is what I thought too, something like that would make all the planets

wobble, we don't have a binary star system. I think it is wishful thinking yet I say goodluck to the scientists out there looking for it. A 26 million year orbit is a curious theory.

[karadax]

11. As we discover more earth like worlds in our neighborhood

the key question of "is there more advanced life" will be answered and replaced with "where are they now?"

Currently we have about 32 planets that are pretty close to the same composition of Earth. They're also pretty darned close (closest is 12 light years while the farthest is nearly 2600 light years) We can keep an ear and eye on them from now on in the hopes that someone is there. Those are the worlds that if there was advanced life we'd probably already know it. That's not to say those exoplanets aren't crawling with dinosaurs or mer-people. My belief is that we're the most advanced people in our neck of the woods. Other than us it's pretty boring over on this side of the Milky Way.

Now we just need to send some probes to some of these planets.

[ChisolmTrailDem]

12. But isn't the flip side of this particular scenario quite exciting to think about?

Just as sure as the life on millions (if not billions) of planets were flash-in-the-pan and probably never made it to the point of being able to send a radio signal to the stars, there are millions out there that are at a plus-or-minus stage of development, compared to us. And, there are millions out there who have far surpassed us in our development and many are space-faring civilizations that are exploring their solar systems, though most likely held to the same Laws of Physics that tie us, perhaps eternally, to our local space neighborhood. Which means there's probably not a star wars going on somewhere in the universe and there likely never has been.

[geek tragedy]

13. somewhere an alien species is wondering why they haven't heard from us nt

[Arugula Latte]

15. Even if only a teeny tiny fraction of a fraction of planets can sustain life for eons,

that is still a huge shitload of planets.

[hunter]

16. The universe is very big, we humans are very small.

We humans are such mean stupid fucks we can't even recognize all the other intelligent species we share this planet with, sometimes not even our fellow humans.

[darkangel218]

55. +1 million

[GreatGazoo]

18. This theory seems to project Mankind's unreasonable disposition onto other species

A planet dominated for eons by an intelligent species that is more herd oriented would likely be more unified. Something like intelligent dolphins or dogs with thumbs disposition-wise.

Some combination of a more cooperative dominant species and multi-generational knowledge could have a very different outcome than the one we are headed for. Native Americans lived on our continent for at least 5000 years without fucking it up so another longterm outcome is possible, even for humans perhaps.

[kentauros]

20. My only major problem with SETI

is that it assumes any technologically-advanced species communicates by radio. What if they use gravity waves instead? Still, that's restricted to the speed of light, so one can assume if they know how to manipulate gravity that they've likely learned about quantum physics.

We humans know that communication over quantum entangled pairs is better than the best encryption we have invented and that such communication may be instantaneous. It's also supposed to be undetectable by outside observation. Radio spreads everywhere. Entangled particles are restricted to those entangled pairs. They don't bleed radio waves we can detect and then use to listen in.

And that's just what we humans know now in our current level of technology. If other civilizations are even just a few decades ahead of us, we likely will never know it, unless we're lucky enough to see something they've built in space.

[Katashi_itto]

23. Agree. What if the Greek Culture continued to thrive? We would likely be far more advanced than we

are now.

[kentauros]

27. I don't know if it was specifically described as part of the Minoan civilization or not,

but the people that lived on the volcanic island of Thira (current-day Santorini) were quite advanced. I recall reading a comment by an archaeologist about them that if Thira hadn't blown up (and then given rise to the Atlantis myth) that they'd have had television by the time of Christ

[Katashi_itto]

31. Agree

[nadinbrzezinski]

24. I think everybody will achieve radio

but I also believe it will be fairly short in the overall history of a civilization.

I also believe we are well on our way to commit suicide and most do in fact.

[kentauros]

26. Well, the biggest problem with radio

is that it thins out fast. Unless said civilization has discovered some way of focusing radio in a way that it loses minimal power and doesn't spread even a tenth as much, we'll never be able to discern it from background radiation.

It's not going to be like in the movie Contact

[nadinbrzezinski]

34. That is true, but it is also easy technologically

anything beyond radio, at least for now, is akin to magic for most humans, Shit, radio is akin to magic for most humans. So I do not expect more advanced methods to be readily imagined by most.

Incidentally this is why in a SF story I am working on, one way to stay off the radar as it were is precisely never even reaching radio

[kentauros]

47. We also have to consider

that other civilizations aren't going to think like humans. For all we know, they develop high tech earlier/faster than us because their minds are geared that way. I've never actually read anything by Stanislaw Lem, but his big thing was to attempt to portray just how alien any other races would be from us. There would be no common ground for communication even if they did use radio.

I was thinking earlier that another big problem with radio is how stars are also huge radio emitters. Anything produced is going to get drowned out over the extreme distances between them and us.

[nadinbrzezinski]

49. True, very true

I can personally foresee a very short window for radio, even as something people do as hobbyists. (Meaning not large big transmitters)

[longship]

37. Well, 1 over r^2 is geometry.

The only alternative is directed narrow communication, like with LASERs, which will still dissipate.

But once one posits directed communication one has another rather large problem, where does one direct it when there are a couple hundred billion stars in the galaxy?

The problem is always what does it take to be detected? Or to detect?

[nadinbrzezinski]

50. There are many problems with this

why earliest quasars were ahem... confused for an alien signal.

[Fumesucker]

60. Pulsars, not quasars

[kentauros]

53. I don't know the geometry reference.

Plus, what I know of science is strictly a layman's point of view. I have no science background other than a few courses in geology (forget chemistry and calculus as I flunked them.) Trig was relatively easy, but I'm too tired at the moment to think in those terms.

And yes, I remember about lasers, as well as how much the spread becomes from just bouncing a beam off of the Moon. Seems like it spreads out over a mere 1/4 million miles distance to something like ten meters across on the surface of the Moon.

Plus, like you say, one has to direct that energy at a spot where you either know or surmise that there might be life technologically-advanced enough to pick it up. And then, they've got to translate it, if that's even possible, re- the alien-mind problem.

Honestly, I'd rather use SETI's funding for spotting asteroids and then moving them out of Earth collision courses (or mining them for materials to make more asteroid-moving robots.) Yeah, we'd have to supplement to fund all of that project, but I see that as doing more good for us overall than SETI's current efforts.

[hfojvt]

61. light waves dissipate as much as radio waves

and yet we can still see stars that are very far away even with small telescopes. The ability to pick out a signal depends on your detection equipment.

[longship]

62. Radio waves and light waves are the same thing.

They only differ in wavelength.

So said James Clerk Maxwell:


In the fourth equations:
Mu-nought * Epsilon-nought = 1/c^2
Where c=speed of light.

[kentauros]

64. However, stars are also much larger

than anything we can build, much less power. And our radio waves were only meant to broadcast over the surface of this planet, not with the intent of contacting other races. Plus, the atmosphere and magnetic field knocks out much of what's leftover.

Sure, a race more advanced than us is likely aware that we exist because they have technology to pick us out of the background noise. But I don't feel our technology is quite that sensitive. Maybe in another couple of decades, if we're even still using radio ourselves.

[roamer65]

25. I honestly believe the first major step any civilization has to make it past is...

NUCLEAR WEAPONS.

If any civilization can make it past the development of them, without using them...they have a shot at survival.

[Mike Nelson]

30. We've really only fully examined one world in one solar system.

There is life here. The life cycle is very prohibitive, but I think most solar systems have some stage of life. The space between stars is so vast, communication must be rare.

[hatrack]

51. And, judging by current events, we don't understand it all that well . . .

.

[FLPanhandle]

32. If by some remote chance intelligent life does appear, it may not last long

From H-bombs, environmental destruction, or just improving medical care until they breed like lemmings causing the population and civilization to collapse (my prediction for us)

[NightWatcher]

35. They're silent because they see our satellite tv signals and know we're bumpkins

Between our news, reality shows, and church programs, they remain silent because they know we're not ready for them to show themselves.

If they did, half of us would fall to our knees in prayer for weeks on end, half of us would try to shoot them, half of us would stare at them while picking our noses, and only a few of us would let them be or try to engage in enlightened conversation.

We are the trailer park at the end of a dirt road in the Alabama of the universe. (No offense to any residents of trailer parks in Alabama, here)

[longship]

41. Fucking "I Love Lucy" alone would have done it.

Let's stay away from that!!!! And whatever you do, don't point any transmitter towards that place.

And what the fuck is Geritol?

[sibelian]

43. Yeah, we're probably on a galactic-scale wildife reservation

[jberryhill]

52. probably something they picked up from the Egyptians or Mexicans

[Travis_0004]

54. .

For a more serious reply, here is an interesting (but long article) on the subject.

http://waitbutwhy.com/2014/05/fermi-paradox.html

[Shandris]

56. Hrm. Could be. But that interesting, quiet monolith we found might mean something else, too.

Consider the following.

Two HUMAN hunters are traipsing through the forest, talking amiably about beer and NASCAR. Meanwhile, off in the distance, the hungry BEAR is eating some berries.

HUMAN: "Why, John, did you see that there NASCAR race last night? That driver dun did good!"
HUMAN2: "Are you kidding me?! He stole that right turn straight off of the driver in the red car! About ran into him!"

The HUMANS continue to chat loudly as the BEAR overhears them. The BEAR, realizing they are not the kinds of entities he wishes to meet, quietly moves off.

HUMAN: "Well ain't that strainge? Ain't seen no bears! Bassards must all be dead."

[closeupready]

58. Think about it - civilization requires the domination of other life forms.

Therefore, in the event of a civilization-threatening crisis (which seems to happen all the time, in geological terms), the dominant life form would exploit other life forms in order to bridge the gap. So yeah, I think this is correct. K&R

[Lydia Leftcoast]

59. The main obstacle is the distances involved

The nearest star is 4 light years away. That's in the quadrillions of miles.

May I remind you that it took 36 years for the Voyager 1 probe to leave the solar system?

It took 9 years for the New Horizons probe to reach Pluto.

[Warren DeMontague]

63. I think it "has to do with" the fact that the Universe is really fucking big, and we haven't even

begun to really look.