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Saturday, November 10, 2018

Is Anybody Out There?

Back in the 1950s, Enrico Fermi posed the eponymous paradox: surrounded by an uncountable number of stars, why haven't we encountered extra-terrestrial intelligence?

After all, no matter even if life, and subsequently intelligent life, is statistically unlikely, its existence elsewhere is statistically certain. Further, since it is extremely unlikely that humans are the first intelligent life to emerge in our galaxy, then the seeming absence of intelligent life is a puzzle that needs explaining.

A decade later, Frank Drake formulated an equation supplying the terms that must be considered in contemplating how many extra terrestrial intelligences (ETI's) there might be.

In successive decomposition, it goes something like this: the number of stars, the fraction that have planets, the fraction of those that have habitable planets, the fraction of them that go on to develop life, the fraction of life bearing planets that yield intelligent life, the fraction that release detectable signals into space, and the duration those signals are emitted.

Of all those parameters, only the number of stars is approximately known, is large enough so that even the multiplicative combination of very low probabilities means the existence of ETI's is certain.

There are two potential resolutions to the Fermi paradox.

The first wasn't even remotely predictable in the 1950s and 1960s. At the time, radio and TV signals were often broadcast from 100,000 watt transmitters. What no one could predict then is a near certainty within a couple decades: our planet going dark. The combination of low power satellite transmitters, cellular networks and near-pervasive landline networks have rendered high power transmitters all but obsolete.

Now that alone doesn't eliminate the Fermi paradox, because even if other ETI's don't radiate enough energy to be detectable is of no real help. The likelihood that even one ETI has developed long before we did is a near certainty; therefore, such a civilization should long ago have pervaded the galaxy.

That, in turn, requires a more or less heroic assumption — that moving even anything more than trivial masses to other stars is possible.

Taken in combination, it is possible that the galaxy is littered with ETIs that will be forever confined to their stars, and undetectable from every other ETI.

But what if the certainty the Drake Equation predicts is? What if there has been widespread optimistic presumptions about some of its elements greatly overstating their likelihood?

The problem with the Drake equation is that it provides discrete estimates to each of the factors.

To quickly see the problems point estimates can cause, consider the following toy example. There are nine parameters (f1, f2, . . .) multiplied together to give the probability of ETI arising at each star.

Suppose that our true state of knowledge is that each parameter could lie anywhere in the interval [0, 0.2], with our uncertainty being uniform across this interval, and being uncorrelated between parameters.

In this example, the point estimate for each parameter is 0.1, so the product of point estimates is a probability of 1 in a billion. Given a galaxy of 100 billion stars, the expected number of life-bearing stars would be 100, and the probability of all 100 billion events failing to produce intelligent civilizations can be shown to be vanishingly small: 3.7 × 10−44. Thus in this toy model, the point estimate approach would produce a Fermi paradox: a conflict between the prior extremely low probability of a galaxy devoid of ETI and our failure to detect any signs of it.

Instead, the authors account for our uncertainty by applying a Monte Carlo simulation — randomly assigning a probability in the range [0, 0.2] for each factor, then combining the values for each of the factors.

The result?

More than 22% of the simulations produce a galaxy devoid of even one ETI.

But wait, there's more.

If, instead of assigning point probabilities to each factor, model each factor as itself a combination of factors. Take the existence of life as an example. Abiogenesis is a transition from non-life to life that "… occurs at some rate per unit time per unit volume of a suitable prebiotic substrate." Using informed guesses about rate, volume, protein folding, etc, yields a range of estimates for the existence of life on suitable planets spanning 20 orders of magnitude. (There is much more to this than I am presenting, btw.)

Applying uncertainty distributions reflecting current knowledge to each of the factors in the Drake Equation, what do you suppose the likelihood is that we are alone, not just in the galaxy, but in the entire observable universe?

Nearly 38%.

I sure didn't see that coming.

Friday, November 02, 2018

The Next One Is Always The Enemy

In the comments for the previous post (The King of Cattle), Clovis wrote: "The next one is always the enemy..." I started responding in a comment, but I decided to make this verbiage its own post because it was getting a bit far off topic. And hey, I haven't posted in a while, so two birds with one post and all that...

I think viewing others as enemies is an inherent part of the human condition. Anyone not part of our tribe(s) is a potential enemy and we (many of us) are continuously monitoring those outside our tribes for signs and symptoms that they are the enemy and the most trivial bit of evidence is taken as conclusive that they are indeed the enemy.

I believe that the period from the end of WWII until now (and hopefully at least a while longer) was one of a very unusual and probably unsustainable peace and a workable type of tolerance. By workable type of tolerance I mean this: sure, there was still plenty of suspicion, prejudice and hate between tribes/nations, but the world was so weary of war and violence that for those decades a substantial majority of people were willing to tolerate otherness and perceived slights, insults, injuries, etc. without a willingness to try to obliterate that otherness or right the wrongs of the slights, etc.

Sure, that's a tremendous simplification and yes, I'm aware of other factors like amazing prosperity on the one hand and Mutually Assured Destruction (MAD) on the other had a lot to do with the workable tolerance as well. For example, MAD allowed us to still have the "other" to hate, an enemy to blame the ills of the world on, but in this case we were able to do it without massive war (barely!). However, that fits into this paradigm I'm describing here fairly well.

From an evolutionary point of view, our capacity (and dare I say need?) to hate could very possibly have a purpose: to spur us to violence and war to take out competing strains of DNA. Hitler used DNA supremacy as a reason for genocide, but Hitler was neither the first nor the last leader to hate the Jews and the Jews themselves are not immune from hating.

Note that I'm not saying that hate and genocide are moral, right, excusable, or anything like that. Instead, I'm saying that to be moral we have to fight with everything we have against our own inherent human nature and if we let down our guard for even a brief instant, horrific evil can and often will follow. Even worse, it's almost certain that from time to time our vigilance will slip and violence, war, genocide and other massive atrocities will follow.

Some of us were alive and aware during WWII. I wasn't born until after WWII but my parents' generation was very, very much aware of the horrors of that war and the memories of WWI. It seemed to me that those wars had an extremely powerful antiwar effect on that generation and on their children (such as me). Now that period is ancient history and even the cold war is something most of the younger generation has only a dim awareness of.

Having very real and mortal enemies is long past, so our younger generation is looking for new ones. And sure enough, they find enemies everywhere they look. Some of the ones looking hardest for enemies are called Social Justice Warriors.

The "Social Justice" part of that label is interesting because it begs the question of whether or not there's a difference between "Justice" and "Social Justice." If they're the same thing, why waste the space by prepending the word "Social"? If they're different, another way of saying something that isn't "Justice" in "Injustice" which is both shorter and perhaps less misleading. [Note that this observation isn't original to me but I can't find a link at the moment in order to give proper attribution]

But the more important part of that phrase is "Warrior." What we have is a fairly large group of people who very much want to be warriors. In other words, to find enemies to hate and fight. They claim to hate and fight those who hate, yet they're obviously uninterested in hating their own hate.

I would say, like many who've come before them, they've let down their guard against their own human nature and I doubt that anything good will come of it and perhaps evil will arise instead.