I write the question to include humans, because irony makes you look at yourself, and this will be highly relevant, as you will see.
I like the Closer to Truth interviews, this one perhaps to short to raise expectations, yet I reflect on why Carr appears so strikingly unconvincing here. The take-away is that he brings up the wrong arguments and balances them with other wrong arguments to arrive at a hunch, and this is the nub.
The Drake “equation” and various uniqueness arguments apply less and less as data comes in. This should normally be a sign that something is wrong, yet they’re brought up.
Surely, if we are intelligent and are to speculate and form principles, it should be from data? (Rather than as Drake later admitted, making up factors and multiplying them together. What the factors are doesn’t matter, as long as there are enough of them it will result in a low number, as Carr and Drake well knew.)
The best way for this seizure on our minds to end, and to form the best prediction we could make, is to project the data we have onto our knowledge about the Universe:
- We know that it takes a certain number of billions of years for the correct generation of stars to expel the heavier elements needed for Life Chemistry to occur.
- We have a measured sample of Earth-like planets defined by just this Chemistry.
- We have a sample of 1 as to how long it takes for this Chemistry to evolve Intelligent Life (if we say so ourselves). In this one sample, Intelligent Life survived asteroids and multiple orders, even classes extinctions, and unintelligent world wars.
The reasonable speculation would be to project the data we have, for a low estimate of how many solar systems are as unintelligent as we are – having built no observable structures, having financed no radio beacons into space, and having ventured a measly few kilometers into space. – If anything, the Universe is behaving as expected, “today”.
The natural thought from this, however, is more intriguing.
If we follow the same Universal Chemistry principles that we follow in gathering all of our knowledge about the Universe, the prediction should be that all planets suitable for Life Chemistry have evolved for as long as we have, and is therefore ready to do all the things we expect of ourselves to make ourselves noticed at this star generation age.
So, the natural expectation would rather be that Intelligent Life is roughly where we are on the cosmological clock of chemical reactions, measured by star generations, each on their individual planet, and is as ready to explode onto the scene as we are. On the Cosmological time scale, I think a 100,000 years long explosion could be considered a true explosion.
As for “them” not communicating randomly with everyone, the general answer is, again: “do all the things we expect of ourselves to make ourselves noticed” as per above, but within this answer, there are many more answers.
One such answer could well be that they solved their habitation problems, and simply don’t need to reach out, or expand.