OK, so I have the answer, and it’s simpler than you think.
The Fermi Paradox is Dr. Enrico Fermi’s 1950 rejoinder to the contention that using a little math one can calculate a million or more alien civilisations in the galaxy: “so, where are they?” The idea is that if there are that many then surely if they’re not here then we’d be able to detect at least ONE. And yet… we haven’t done so.
And nor will we. The proponents of this thinking make assumptions. Drake is the guy who formalized the equation for calculating the count of alien civillisations. Kardaschev postulated type I thru IV based on how much energy they require to exist; his scale says that a civilisation has to be close to the point of eating every watt of energy output from the host star before it goes interstellar. Look up Fermi Paradox on wiki and you’ll see a boatload of arguments based on resources, like eco disaster, pollution, squandering all of the native fossil fuels, etc. All of the arguments for and against are based on the assumption that civilisations need raw materials (resources.) These assumptions are probably wrong.
Here’s why. In the 1980’s IBM made news by making an IBM logo on an IC chip. It was atomic. Individual atoms were moved into place. Not too long ago there was a science news article regarding manipulation of atoms, and another was about techniques of forcing atoms to bond to desired targets by blowing off outer ring electrons. You see where this is going. It won’t be that long (25 years? A century? Two? Who knows?) before someone figures out how to marry computer software horsepower to atomic manipulation. Sure, it requires a bit more than we presently know. But this is something that will happen. The question is when.
What that means is that when the technology is mature, you can have a machine where you dump in dirt, leftovers, and used car parts… and out comes hamburger or a gold necklace or a better remote control than the one you lost last week. Atomic construction. Unless said construction requires the energy of the sun, that means the resource argument is moot. There would be no need for us to scour the asteroid belt for metals, mine lunar H3, and so on. In other words, resources themselves would be moot.
Now, where this thought meets Dr. Fermi, consider the assumption that galactic expansion is driven by the necessity of gaining increasingly more resources. Ummm, No. Liebensraum? Probably. Resources? No. My guess is that once a civilisation acquires this technology, it will take decreasing energy to make all the widgets and food desired — which is precisely the opposite of what Kardaschev postulates. And what energy *is* needed can probably be supplied by advanced energy technologies anyway (e.g. fusion.) There wouldn’t be a need to expand into the galaxy save for the sheer sense of adventure of doing so and of course to provide a place for the inevitable latter day equivalent of Mayflower pilgrims.
A new article from Russian scientists says that metallicity of the sun happened later than anyone thought, suggesting that the argument of “in 10 billion years we ought to have had a civilisation appear” is wrong as well; the time frame is considerably shorter. We may be the first or the only or among the first, and if *we* can figure out how to turn rocks and leaves into usable stuff and food, meaning *we* won’t need to colonize the galaxy for the resources, then this discovery is probably de riguer for all civilisations advanced enough to seriously consider colonisation as a viable option in the first place. Atomic manipulation pretty much trumps almost everything. We won’t go to alpha centauri unless we want to do so. Going beyond some reasonable limit, say 250 LY, is improbable.
In short, if they exist, they’re at home, or close to it.