# Thursday Throughput: Are We Alone Edition?

Michael Siegel

Michael Siegel is an astronomer living in Pennsylvania. He is on Twitter, blogs at his own site, and has written a novel.

### 26 Responses

1. George Turner
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says:

I agree with Crichton on the Drake equation. You could append it with terms for the average size of each civilization’s war fleet, the average number of photon torpedoes per warship, and the average yield of each photon torpedo to calculate how much firepower alien civilizations posses.

And you can also add a couple of more terms, Pop * Pc * Pn * Hf * Gf, which is the population of each civilization, the percentage that drive convertibles, the percentage that are hot nymphomaniacs, and the percentage of those that have a fetish for humans, and the percentage that have a thing for geeks, to calculate the universe’s total count of hot alien nymphos in convertibles who would date human geeks.

So then you know how many available alien girls are out there and how many photon torpedoes you’ll have to deal with before you get to date them, and that lets you size your ship’s deflector shield generator. It’s science!

I can’t see how it’s any different from multiplying the size of an angel and how much open dancing area each one needs to accurately calculate how many angels can dance on the head of a pin. We were calculating things like that prior to the scientific revolution, and apparently we’re still calculating like that today. The folks at the Creation Museum in Northern Kentucky can do all kinds of math on the required storage space in Noah’s Ark, too.
That’s because we can calculate anything we can dream up numbers for, and we can crunch numbers on a fantasy universe just as easily as a real one. It’s just much harder to get repeatable measurements on the fantasy.

Sure, we have much better data on the number of planets in the habitable zone, but we also have much better data on the size of commercial pin heads. But until we have solid numbers on angel sizes, the output of the dance calculations will remain clouded with doubt.Report

• Michael Cain in reply to George Turner
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says:

The Fermi Paradox and implied Great Filter are much more fun to argue about. The comment section of the post where Charlie Stross invited readers to speculate on the possible nature of a future Great Filter is interesting.Report

• Christopher Carr in reply to George Turner
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says:

The Drake equation is an absurd tautology. Anyone with an intuitive sense of math as a language should grasp that. I remain shocked that there are those who don’t realize any discussion of the Drake equation is just like arguing how many angels could dance on the head of a pin.

My favorite version goes something like this:

N = F(L) * L, where N is the total number of aliens, F(L) is the fraction of aliens per laser and L is the number of lasers in the universe.

The advantage over your hot nymphomaniac aliens in convertibles is that mine conforms much more closely to Occam’s razor.

(I can’t remember where that came from. It could have been here.)Report

• George Turner in reply to Christopher Carr
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says:

You could also make a solid argument that the equation is also wrong.

N= R* * fp * ne * fl * fi * fc * L

where

R∗ = the average rate of star formation in our galaxy
fp = the fraction of those stars that have planets
ne = the average number of planets that can potentially support life per star that has planets
fl = the fraction of planets that could support life that actually develop life at some point
fi = the fraction of planets with life that actually go on to develop intelligent life (civilizations)
fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
L = the length of time for which such civilizations release detectable signals into space[5][6]

Well, L won’t depend on R* because R* can drop to almost zero when an ultra-massive black hole gets weird and disperses a galaxy’s star-forming gas clouds, making the entire galaxy look red because the young blue stars are missing. Yet all the old stars still burn just fine, and the continuing biological and social evolution on the existing planets will be relatively unaffected.

You could also have a young galaxy with a very high rate of star formation, where R* is staggeringly large, yet where none of the stars would be older than a hundred million years, so L could be zero because there hasn’t been enough time for complex life to evolve even with large R* and all the other terms being also quite large. Since L can be either zero or quite large while R* is ranges the opposite way, from huge to zero, any clear linear relation between L and R* isn’t necessarily valid, and thus the R* term is incorrect. A more correct term might be the number of pretty old, pretty stable stars in a galaxy, but even there, it would make sense for intelligent civilizations around old stars to relocate to all the young new stars, so even that fix falls short.

The next four terms are just a round-about way of saying “the fraction of stars that have intelligent life” and trying to make it look sciency. It’s also wrong. The terms could multiply together to give just one planet that developed intelligent life, but that life could’ve gone on to terra-form and colonize 10,000 planets over time, developing 10,000 different civilizations we might communicate with.

Taking things term by term, the fraction of stars that have planets, fp, can safely be taken as one, so it’s useless as a multiplier. The next term, the fraction of planets that can potentially support life is also one, because “potentially” conjures up all sorts of possibilities, from silicon based life that lives at 1000C to sulfur eating blimps that live in the atmospheres of gas giants. Potentially there could be plasma based life forms that live in red super giant stars, so why are we even fixating on planets? So let’s call that term one, which is multiplied by the one in the previous term, to give one.

The next term, the number of planets that do develop life, is unknowable without statistically sampling a large number of planets by going there and looking for bacteria. We didn’t even know much about archaea deep in the Earth until recently, so there’s no way we’d detect them from space. Heck, we have yet to determine if Mars harbors life, so by the time we have a good statistical sampling to give any validity to determine fl, we’ll already be on our way to joining a trans-galactic trading empire, or establishing our own, and the equation will be moot.

The same situation applies to fi, the number of planets with life (which we won’t know until we physically measure it with sampling probes) that develop intelligent life, which we’ll have to determine by showing up and giving them IQ tests. The only way to determine fl and fi is by taking a census of the planets around a large sample of stars, at which point we won’t need the Drake equation because we’ll just multiply the fraction of stars where we found intelligent life in our sample by the number of stars in the galaxy to give us N.

fc, the fraction of civilizations that can be detected from space, has a value of one, since almost by definition a civilization is detectable from space because even a single medieval village changes the planet’s photon emissions to space, otherwise an orbiting recon satellite couldn’t see the village. I suppose you could argue for a civilization hidden under the clouds of Venus or at the bottom of an ocean, but at that point you trying to count civilizations that an on-site survey team would miss. What sense would it make to include the number of civilizations we’ll never find, since it’s an unknowable unknown?

And L is likewise unknowable, because we don’t even know if any civilization ever emits detectable signals into space when you consider interstellar distances. Unless one builds a giant antenna and beams multi-gigawatt signals at all the nearby stars, and does so for hundreds of thousands of years after it’s obvious that it’s a pointless waste of time, L is effectively zero. If the lifetime of a civilization that could pointlessly beam signals into deep space is large, then they could also have just seeded the galaxy with trading posts and L is moot.

But other than those flaws, it’s a great equation, the very pinnacle of science, ranking right up there with E=m^2 or quantum mechanics.Report

2. fillyjonk
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says:

ThTh8: Are we absolutely sure that’s not a video run backward, where some jerk took a nicely sorted tray of nails and messed them all up? I have never found “shake it for a while” helped the organization of anything, but then I don’t work with nails on the regular.

I suppose I could dump my sewing pins in a box and try it; pins and nails are similar.Report

• Oscar Gordon in reply to fillyjonk
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says:

It’s not really order from chaos, it’s just the physics of friction. This is a well known and well documented phenomena. As you shake the box, some of the nails will align by chance, and once they do, they will have more surface in contact that nails that are not aligned, thus they will stick together. As more nails randomly align, you eventually get to a point where the aligned nails start forcing the unaligned nails into alignment, and the whole this quickly snaps into alignment.Report

• Michael Cain in reply to Oscar Gordon
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Do the nails always align themselves along the long access of the container? What happens if the length of the container is not a nice integer multiple of the length of the nails, as appears to be the case in the video? I ask because the ever-popular metronome synchronization demos only work under specific sets of conditions.

• Oscar Gordon in reply to Michael Cain
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says:

IIRC, the container length and how it’s shook are important, but it’s not a precise requirement (i.e. the container does not need to be a specific integer multiple, but it needs to be in the ballpark of one).Report

• Chip Daniels in reply to Oscar Gordon
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says:

I’ve actually done the shaking thing to organize containers of small linear objects and part of it is that the motion needs to be horizontal.

It takes more energy to get them to rise up and go crossways than it does for them to fall by gravity into the grooves which are created when two or more align, like you mention in your first comment.

If you shake vertically, the pieces jump up and down and then won’t align ever, because you are inputting the energy needed to overcome gravity.Report

3. mistah charley, ph.d.
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says:

thth13 – you might could wait on booking your trip – summer vacation might not happen this year – although it’s hard to make predictions, especially about the future – and those destinations that are open may have bargain ratesReport

4. Oscar Gordon
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says:

ThTh14: Yep, it’s not plastic, per se, that is the issue, but plastic that is NOT in the managed waste stream.Report

5. Michael Cain
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says:

Thth10: One of the difficulties is that many of the responses to an oil price hike, such as buying a higher-mileage car, take years to occur. We do know that in places that have imposed sustained high consumer prices for petroleum products (eg, European pump prices due to taxes) people drive much smaller cars and build/use more public transportation. UK pump prices today are just over \$6 per US gallon. If we took US prices to that level and left them there for a decade it would almost certainly lead to decreased demand.Report

6. Brandon Berg
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says:

Slaughtering all the cows is not something that’s going to happen any time soon.

Well, not all at once. But I wouldn’t go into business selling life insurance to cows.Report

7. CJColucci
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says:

Three possibilities:

1. We are alone.
2. We’re not alone, but we’ll never be able to know.
3. We’re not alone, we’ll find some good evidence that we’re not alone, but there will be no way to communicate with whoever is out there.

I’m not sure which is more depressing.Report

• Michael Siegel in reply to CJColucci
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says:

I give a lecture on SETI that I call “Dr. Siegel crushes youthful enthusiasm” I ask them the question of whether we will hear from aliens at the beginning and then again at the end. They always get more pessimistic. 🙁Report

• North in reply to CJColucci
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says:

Yeah, once I internalized the very real possibility that information cannot travel faster than the speed of light and looked at how fishing huge the galaxy is? I have trouble not writing off the idea of intelligent life out there as being entirely and irrelevantly academic.Report

8. LeeEsq
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says:

Most science fiction dealing with alien life depicts them as more advanced than we are or at about the same level. An interesting and to my mind unexplored alien life form plot would be that alien life exists but hasn’t evolved to our level yet. It is basically planets filled of wild animal life.Report

• fillyjonk in reply to LeeEsq
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says:

Or planets full of bacteria-analogues, which I think is by far the most likely possibility for “extraterrestrial life.”

there are a lot of ways to be a single cell, lots of metabolic pathways open to you if your energy requirement is lower….Report

• North in reply to LeeEsq
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Them aliens better hope they’re either too far away from us or too dissimilar from our biology for they or their planet to be of any practical use to humans or it’d turn out mighty badly for them.Report

9. Pinky
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says:

ThTh6 – Why would the galaxies blast out like that? I’d think that gravity would pull things together. I mean, planets could get knocked out of orbit, but their mass is negligible compared to the stars, right? And that animation isn’t simply showing debris. That’s a galaxies-wide blast zone.Report

• Michael Siegel in reply to Pinky
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says:

They will pull together. If you run the simulation for another few billion years, the galaxies will eventually merge. You get a lot of debris thrown out because of N-body interactions.Report

1. October 8, 2020

[…] water. This information, all of which has come about in the last twenty years, has allowed us to speculate about life in our Galaxy on a scientific basis for the first […]Report