Astrophysicist Believes Technologically-Advanced Species Extinguish Themselves (sciencedaily.com)

Why haven't we heard from intelligent life elsewhere in the universe? wisebabo writes: In the Science Daily article "Where is everybody? The Implications of Cosmic Silence," the retired astrophysicist Daniel Whitmire explains that using the principle of mediocracy (a statistical notion that says, in the absence of more data, that your one data point is likely to be "average"), that not only are we the first intelligent life on earth but that we will likely be the only (and thus the last) intelligent life on this planet... Unfortunately that isn't the worst of it.

Coupled with the "Great Silence", it implies that the reason we haven't heard from anyone is that intelligent life, when it happens anywhere else in the universe, doesn't last and when it does it flames out quickly and takes the biosphere with it (preventing any other intelligent life from reappearing. Sorry dolphins!). While this is depressing in a very deep sense both cosmically (no Star Trek/Wars/Valerian universes filled with alien civilizations) and locally (we're going to wipe ourselves out, and soon) it is perhaps understandable given our current progress towards reproducing the conditions of the greatest extinction event in earth's history.
That last link (reprinting a New York Times opinion piece) cites the "Great Dying" of 90% of all land-based life in 252 million B.C., which is believed to have been triggered by "gigantic emissions of carbon dioxide from volcanoes that erupted across a vast swath of Siberia." But if we're not headed to the same inexorable doom, that raises an inevitable follow-up question.

If intelligence-driven extinction doesn't explain this great cosmic silence, then what does? Why hasn't our species heard from other intelligent civilizations elsewhere in the universe?

Comments

time and distance scaling

[cats-paw]

As has already been demonstrated by the permian extinction event, the biosphere can take a hell of a hit, and life will go on.

I think that you really have to understand timescales here. A 100 million years is a long time, just like space is big, really big. So that's a long damn time, and life will go on. intelligent life, maybe not so much.

as for why we haven't heard from anyone, why isn't the simple answer not the best ?
Remember how space is really big ?

if there's no FTL travel, and it's likely there is not, then HOW would we hear from someone ?

It would be an exceedingly difficult thing for the intelligent civilization in the Andromeda galaxy to talk us, and us to them.

First of all, there's the 2,000,000 year latency, and then the amount of power you would need to transmit that signal, etc...

I'm not worried. There's intelligent life elsewhere in the verse. I'm pretty sure we're not going to hear from them any time soon, if ever.

Re:time and distance scaling

[JoshuaZ]

The problem though isn't deliberate communication, but rather twofold:

First, a complete lack of evidence on a large scale of anything we'd expect to see. We have some pretty concrete ideas about construction of megastructures, such as Dyson spheres, the more plausible Dyson swarms, stellar engines (where the Class A version https://en.wikipedia.org/wiki/Stellar_engine#Class_A_.28Shkadov_thruster.29 is essentially doable if one has enough material and doesn't require any exotically strong materials or the like), and many more. But we don't see any signs of any of those. And most of those will *last* for very long times once constructed. And we have searched for them both here http://home.fnal.gov/~carrigan/infrared_astronomy/Fermilab_search.htm and in other galaxies. In a similar context, we've looked for signs of K3 civilizations in about 100,000 galaxies and found essentially no signs of them https://arxiv.org/abs/1504.03418.

The second problem is that if a species does survive even a relatively small amount of time, it should be able to spread throughout a galaxy. Yes, galaxies are really big, but the space is not as big as the time available. For example the Milky Way is about 100,000 light years across. That means that if a species starts on one end and travels spreading throughout planets at around 1% of light speed (which certainly looks doable) then it takes around a 10 million years for them to spread throughout. That's a tiny amount of time. But we don't see any signs of anything like that.

So there really does seem to be some sort of Great Filter or series of Filters, and the question is whether it is early (e.g. life is hard to arise or intelligence arises rarely) or late (civilizations wipe themselves out). And if it is the second, then we need to figure out what is going on since we don't get a do-over.

Re:time and distance scaling

[Tablizer]

Not necessarily. It's a matter of economics. Sometimes it's cheaper to waste energy than spend resources on efficiency. If fuel is relatively cheap, then efficiency may not be worth the added cost.

Re:time and distance scaling

[slack_justyb]

if there's no FTL travel, and it's likely there is not, then HOW would we hear from someone ?

You say that, but that totally invalidates what you said prior to that.

A 100 million years is a long time

The Andromeda galaxy is only 780 kpc from us. At 99% the speed of light, that's only 2.5 million years. On a scale of 100 million years, that's totally doable multiple times over. That's the huge mystery of the Fermi paradox. Given medium time scales like G-type main sequence stars lifetimes, alien life has had enough time to hop between the big three galaxies in our local group and do a fly-by of the main stars in all three as well.

if there's no FTL travel, and it's likely there is not

Yeah, it's insanely likely that FTL is just sci-fi forever. I personally think anything higher than 90% c is just non-doable. So look back at the last paragraph in my comment. Say we slow everyone down to just 10% c. At 10% c, you can hop from one side of the Milky Way to the other in just a million years. Get to Andromeda in just 25 million years. That's still really short time spans. You could fly to Andromeda, send a message back and the sun still wouldn't have entered it's next phase, one billion years from now compared to 27 million years for what I just described.

First of all, there's the 2,000,000 year latency, and then the amount of power you would need to transmit that signal, etc...

All of those are insanely small scale issues, they're big things to us because we lack the ability to even fly to another planet, but if you're the type of society that can fly at 10% c, those are pretty simple tasks that might take 10k years to build a generator, 15k years to build the transmitter, etc. They just seems like big deals because we're nowhere near that kind of specie.

So millions of years is not a huge amount of time. But more importantly, becoming a traveler of the stars means you don't hold on to where you came from. You travel to Andromeda, that's who you are now. You don't have strong ties to Earth anymore, you're a seed of life, not an explorer. Humanity still clings to this notion that once we start, if we start, traveling the stars that we'll for some reason still treat Earth as this special place that we need to come back to or at the very least report back to. We might send a message, but after that, those humans are now their own thing. The idea of sending people to other planets isn't to save Earth, it isn't even to save our species because more than likely after a few thousand years on a different planet your DNA is going to change vastly. It's to save intellect, to keep the thinking/feeling part of the Universe going. As far as we know we're the first/only part of the universe that's got the thinking attribute and maybe just like how supernovae spread heavier elements, we need to get our butts in gear to start spreading this attribute across the galaxies (just the local group, the idea that we'll ever make it out of the local group is not even real with any kind of advancement). But that's just my take.

TIME is V A S T

[redelm]

Not only is space incomprehensibly vast, but so is time. 16 billion years sounds easy to say, but if an intelligent species only broadcasts "clear", identifiable uncompressed unencrypted radio for ~100 years, then we have only 1 in 160 million chances of finding them with something like SETI.

Do you still use AOL Instant Messenger?

[BLToday]

We're using AIM and we assume if people have internet connection then they must also use AIM. If we see no one on AIM then there must be no one else with an internet connection.

I'm with the theory that we're just at the beginning of life in this part of the universe. 13.7 billion years from the Big Bang. Multiple generations of star formation and death before getting to our Sun. Then another 4 billion years before complex life. Sounds like it takes awhile for intelligent life to get started.

Re:intelligence

[Anonymous Coward]

THEY'RE MADE OUT OF MEAT

"They're made out of meat."

"Meat?"

"Meat. They're made out of meat."

"Meat?"

"There's no doubt about it. We picked up several from different parts of the planet, took them aboard our recon vessels, and probed them all the way through. They're completely meat."

"That's impossible. What about the radio signals? The messages to the stars?"

"They use the radio waves to talk, but the signals don't come from them. The signals come from machines."

"So who made the machines? That's who we want to contact."

"They made the machines. That's what I'm trying to tell you. Meat made the machines."

"That's ridiculous. How can meat make a machine? You're asking me to believe in sentient meat."

"I'm not asking you, I'm telling you. These creatures are the only sentient race in that sector and they're made out of meat."

"Maybe they're like the orfolei. You know, a carbon-based intelligence that goes through a meat stage."

"Nope. They're born meat and they die meat. We studied them for several of their life spans, which didn't take long. Do you have any idea what's the life span of meat?"

"Spare me. Okay, maybe they're only part meat. You know, like the weddilei. A meat head with an electron plasma brain inside."

"Nope. We thought of that, since they do have meat heads, like the weddilei. But I told you, we probed them. They're meat all the way through."

"No brain?"

"Oh, there's a brain all right. It's just that the brain is made out of meat! That's what I've been trying to tell you."

"So ... what does the thinking?"

"You're not understanding, are you? You're refusing to deal with what I'm telling you. The brain does the thinking. The meat."

"Thinking meat! You're asking me to believe in thinking meat!"

"Yes, thinking meat! Conscious meat! Loving meat. Dreaming meat. The meat is the whole deal! Are you beginning to get the picture or do I have to start all over?"

"Omigod. You're serious then. They're made out of meat."

"Thank you. Finally. Yes. They are indeed made out of meat. And they've been trying to get in touch with us for almost a hundred of their years."

"Omigod. So what does this meat have in mind?"

"First it wants to talk to us. Then I imagine it wants to explore the Universe, contact other sentiences, swap ideas and information. The usual."

"We're supposed to talk to meat."

"That's the idea. That's the message they're sending out by radio. 'Hello. Anyone out there. Anybody home.' That sort of thing."

"They actually do talk, then. They use words, ideas, concepts?"
"Oh, yes. Except they do it with meat."

"I thought you just told me they used radio."

"They do, but what do you think is on the radio? Meat sounds. You know how when you slap or flap meat, it makes a noise? They talk by flapping their meat at each other. They can even sing by squirting air through their meat."

"Omigod. Singing meat. This is altogether too much. So what do you advise?"

"Officially or unofficially?"

"Both."

"Officially, we are required to contact, welcome and log in any and all sentient races or multibeings in this quadrant of the Universe, without prejudice, fear or favor. Unofficially, I advise that we erase the records and forget the whole thing."

"I was hoping you would say that."

"It seems harsh, but there is a limit. Do we really want to make contact with meat?"

"I agree one hundred percent. What's there to say? 'Hello, meat. How's it going?' But will this work? How many planets are we dealing with here?"

"Just one. They can travel to other planets in special meat containers, but they can't live on them. And being meat, they can only travel through C space. Which limits them to the speed of light and makes the possibility of their ever making contact pretty slim. Infinitesimal, in fact."

"So we just pretend there's no one home in the Universe."

"That's it."

"

Galactic internet vs crystal radios

[John Jorsett]

For all we know, the universe is all chatting with each other via quantum entanglement or something even more advanced, and we're off in the corner thwacking our electromagnetic equipment on the side saying, "Is this thing on? Where is everybody?"

We could prevent the Great Dying

[Solandri]

cites the "Great Dying" of 90% of all land-based life in 252 million B.C., which is believed to have been triggered by "gigantic emissions of carbon dioxide from volcanoes that erupted across a vast swath of Siberia.

Our technology is to the point where we could prevent a recurrence of the Great Dying. All you have to do is unshackle your mind from the popular notion that the only solution to CO2 emissions is passive (reducing emissions via renewable energy sources).

CO2 (and water) are popular end-products for exothermic chemical processes (e.g. burning gasoline, cellular respiration) because it sits at an extremely low energy potential. That is, chemical processes which result in CO2 give off a lot of energy. To reverse the process, you have to put a lot of energy into the CO2 to break apart the carbon and oxygen atoms.

If you have sufficient energy, you can actively drive that reverse process. Plants do it via photosynthesis, driving it with energy from sunlight. We could do it with nuclear power - generating massive quantities of electricity (more than can reasonably be obtained from solar, wind, hydro) to decompose CO2. Generating sufficient power to offset volcanic emissions of CO2 would be incredibly expensive, but given the alternative (extinction) we're technologically capable of doing it.

The same is true if this push for renewables as the only solution to global warming fails. If renewables can't be developed quickly enough to supplant fossil fuel energy sources and CO2 levels continue to rise, at some point we concede that renewables aren't arresting CO2 levels quickly enough. Then we'll be forced to switch to nuclear power to buy ourselves more time. This is why shuttering operational nuclear plants as Germany is doing is extremely short-sighted. Nuclear is our ultimate trump card. We want to keep it ready in our back pocket as a hedge in case renewable energy can't be rolled out quickly enough.

Re:intelligence

[twosat]

Here's a short film version: https://www.youtube.com/watch?...