[JamesLeonis]

The Drake Equation is filled with assumptions, like life must appear on a planet in the Goldilocks zone of a star. The whole equation has only one datapoint to extrapolate from. Tweak the equation's parameters and it will predict universes that only have one civilization per galaxy or worse! We have no way of knowing what those parameters are because we haven't seen other examples.

A major reason we are interested in Europa is because it might have underground oceans. Hypothetically, through tidal forces with Jupiter, the moon's core is hot enough to create oceans under the ice crust. Combined with hydrothermal vents you have the possibility for deep sea life similar to our own deep oceans. The Drake Equation does not predict this possibility.

[mr_mitm]

The Goldilocks zone doesn't enter the Drake equation at all.

As a reminder, this is the equation: https://en.wikipedia.org/wiki/Drake_equation#Equation

It makes very few assumptions.

[buran77]

The equation itself makes no assumptions. But anyone trying to calculate something with it must.

The last five factors in the equation will be filled in by assumptions based entirely on one data point, life on Earth. From your link:

  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 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.

Can you define any one of those without assumptions, in a scientifically proven way?

[crazygringo]

I'm assuming they were referring to this term:

> n_e = the average number of planets that can potentially support life per star that has planets.

The fact that the planet is neither too hot nor too cold would seem to be a major component of this term:

https://en.wikipedia.org/wiki/Habitable_zone

[hotstickyballs]

The biggest assumption is that it assumes only a single path to intelligent life.

[corimaith]

Even if you only had a handful of civilizations, the sheer time that has passed and size of the universe should mean that life should still be alot more apparent.

With sublight velocities achievable today, I recall it would only take around a million years for a Von Newmann probe to cover the entire galaxy. Such a probe is quite conceivable, so why isn't there more evidence of such probes everywhere?

Another point I feel is that proliferation of life should be an self-reinforcing affair, for intelligent life even more so. A spacefaring nation may terraform or just seed planets, and these in time will replicate similar behaviors. At a certain point, a galaxy teeming with life should be very hard to reverse given all the activity. A life itself isn't necessarily evolved from biology, AI machine lifeforms should also well suited to proliferate, yet we don't see them anyways.

[littlestymaar]

> With sublight velocities achievable today, I recall it would only take around a million years for a Von Newmann probe to cover the entire galaxy. Such a probe is quite conceivable, so why isn't there more evidence of such probes everywhere?

What are the incentives to build and deploy such a thing though? We as a civilization fail to fund things that have a ROI of more than a few years, how are you going to fund something that pays off after a million year?

[mr_toad]

At some point replicative drift will set in. How many replications is two million years? How long before the probes evolve? How long before they speciate? How long before a species turns on itself?

[fooker]

> Such a probe is quite conceivable, so why isn't there more evidence of such probes everywhere?

Time, not space, is your answer here.

Two reasons -

(1) civilizations might not survive long enough to do this.

(2) 13 billion years is a long time. So you have the reciprocal of that as the chances to be in the right year to see such a probe. And with results from the new telescope we now have hints that the 13 billion number is bogus, the universe is likely far older.

[raverbashing]

Yup

The fundamental problem with the Drake equation is that it's frequentist, not Bayesian

Hence why you get too high sensitivity to parameters you have no way of having an estimate with a small margin of error

We "don't care" about how many civilisations are out there, we care to the point where we can interact with them.

As mentioned, it has several assumptions. "Rate of birth of sun like stars" means nothing. You can "always" have an exception for life that will throw the data off: "star too bright but with a hot Jupiter tidally locked in front of your moon, shielding it" etc

[antonvs]

> star too bright but with a hot Jupiter tidally locked in front of your moon, shielding it

It seems unlikely that such exceptions would amount to more than part of a reasonable margin of error.

[adastra22]

FYI just about every outer solar system moon or planetoid has a liquid ocean somewhere underneath. Europa is neither exceptional or even that interesting anymore.

[bethekidyouwant]

Not really there’s always gonna be water comets in the frost zone.