Hacker News Reader

Comment by shiftingleft | Hacker News Reader

The Fermi Paradox has essentially been resolved: https://arxiv.org/abs/1806.02404

This explanation is much more plausible than a Great Filter. Here's a great comment summarizing the argument very intuitively:

https://news.ycombinator.com/item?id=17562439

I also found this one very helpful:

https://news.ycombinator.com/item?id=17564379

View on HN

> However, the result is extremely different if, rather than using point estimates, we take account of our uncertainty in the parameters by treating each parameter as if it were uniformly drawn from the interval [0, 0.2]. Monte Carlo simulation shows that this actually produces an empty galaxy 21.45 % of the time.

Isn't that just elaborated way of saying that some of the parameters of the Drake equation have to be much smaller than we think?

Yeah - but they don't have to be much smaller.

Let's use the simple example you reference from the paper. If we just use the mean as point estimates, then indeed we obtain an extremely low probability that there's no other intelligences:

  def prob_of_no_intelligence_in_galaxy(p):
      prob_of_intelligence = pow(p, 9)
      planets = 100e9
      return pow(1-prob_of_intelligence, planets)

  prob_of_no_intelligence_in_galaxy(0.1) -> 3.720086311124783e-44

However, there is already a 82% chance of an empty galaxy if the parameter p is halved:

  prob_of_no_intelligence_in_galaxy(0.05) -> 0.8225792614407508

Now of course halving every probability is a lot, however now there's no single or few events that have a very low probability of happening. The Great Filter disappears.

See also my other comment here: https://news.ycombinator.com/item?id=25811359

Why do you have 9 factors? The classical Drake equation has 6 (and the L which is the avg. lifetime of the civilization).

Also: The Drake equation has one factor which is the avg number of planets per star, of which we are already quite confident it is above 0.1.

Eh no? The paper basically IS a great filter argument. Life is rare and we are alone. That means there is a great filter behind us.

From the website: "The Great Silence implies that one or more of these steps are very improbable; there is a "Great Filter""

The paper argues against this in that you don't need a few very improbable. In fact, there are many parameter choices where none of the probabilities in the Drake equation are particularly low, yet the resulting number of intelligences is still staggeringly small.

tl;dr: All parameters can be a bit lower. Then you don't need any events that are extremely improbable.

But one of the events must be the least likely. And why would it not be significantly less likely than the next least likely event, given that they are uncorrelated?

>This explanation is much more plausible than a Great Filter.

I don't see how it's any different from the great filter explanation. It's just great filter with statistical distributions.

The Great Filter thesis is that there has to be one or more very low probability events in the Drake Equation.

However, as per my other comments, you can update the distributions of your parameters in different ways, such that none of the events in the Drake equation have a particularly low probability.

Then the Great Filter disappears and there's no specific or few set of events to point to - it's just that the probability of all events succeeding in combination is extremely low.

Reply on news.ycombinator.com