Any kind of organisation at semi-galactic scale implies FTL communication at the very least, which violates everything we know about physics.

Another theory that doesn't require a great filter: The distribution of life may not be equal across the galaxy if it's truly random, we could be in a local minima and never meet another civilisation by the bad luck of where we are.

> Any kind of organisation at semi-galactic scale implies FTL communication at the very least, which violates everything we know about physics.

Never thought of the practicalities of that, so thanks for bringing it up.

I think you're overstating things. Sure, they wouldn't be able to watch the Superbowl at the same time or hold elections in the same decade. It would be a very different and slow moving kind of civilization than what we know.

But I don't see how that means it can't exist, in some form.

"by the bad luck of where we are"

Or perhaps the good luck of where we are

Or, the galaxy is populated, and every entity has developed a policy of leaving everyone alone, so as to avoid detection and subsequent annihilation by other entities. Because as soon as an entity speaks up, everyone else seeks to eliminate it in the fear that it might experience a technology explosion, growing quickly enough to meaningfully compete for resources...

https://en.wikipedia.org/wiki/Fermi_paradox#It_is_the_nature...

Policy of leaving us alone is likely. The reasons are also likely to be mundane. Too far away. We are possibly too far behind or we are so sufficiently behind that bringing us up to speed won't help them or us. Besides, in our primitive ways maybe we have something they lack. Some aspect of diversity.

A more interesting answer is they are simply horrified or disgusted: look up "They're made out of meat!"

Not that hard to believe either. There is a civilization on Earth that the rest of us have agreed not to contact. [0] Occasionally they see our aircraft and we can only assume treat them as mythical beasts. Once someone tried to contact them and was killed.

Is it that hard to believe that our local aliens ignore us for the most part, that sometimes we see their spacecraft and mistake them for natural phenomena, and when one of them approaches illegally if they land in the wrong place they just get killed?

[0] https://en.wikipedia.org/wiki/North_Sentinel_Island

I wonder what they think about all the random garbage the floats onto the shore of their island

Except we're aware of them and they're aware of us.

What would be the "ne plus ultra" of irony is that a hyper-advanced civilization had a policy of leaving us alone because they greatly feared us due to the fact we were thousands of times taller than they are.

Or, its too much work for them to fund SETI research on their planet... and they find that they can spread through the galaxy faster, if they just wait for a civilization to a) announce their presence; b) nuke themselves to the stone ages; c) and leave lots of space for the aliens' 100-year starships to drop off a few million colonist to the 'intelligent' species that just nuked themselves. Slow and steady wins the race.

>The galaxy is populated, much like Earth. The power controlling our region has a policy of leaving us alone. End of story.

Or they just don't care to visit our solar system because there's nothing of interest here. I'm sure you can imagine a 18th century European surveyor sailing past a bunch of new islands, noting them on charts and tossing in the description "contains no resources" and then moving on.

Travel might be terribly expensive and slow even for advanced species, so the concept of "resources" would be meaningless.

Or maybe they've come, but only in very small numbers. They radio home and leave for the next system to explore.

Such as when Abel Tasman explored Australia and New Zealand in 1642, but didn't find anything of interest (trade opportunities) to the rulers in Europe of the time.

If we assume that an advanced civilization will develop machine intelligence on a large scale with efficient processors and vast energy resources, it's possible that they've already fully explored the nature of worlds such as ours, and they don't have any reason to monitor them further.

What if they have visited, a long long time ago. The lead explorer’s name happened to be “God”.

Fermi's counter argument is that there's been billions of years.

Even a slow moving star hopping civilization should have spread across the whole galaxy many times over by now.

The 18th century surveyor skipped some islands, sure. But by now they're all accounted for.

What would be the alien/human equivalent of an airplane that natives in uncontacted areas shot arrows at? I can't come up with a believable example for the aliens to be discussing back at home base.

Mistaking them for natural phenomena. Like asteroids.

> and assumes galactic society is organized much like Earth.

When has earth society ever successfully left something new and foreign alone?

If there is a 'galactic directive' to leave us alone, it's because we were seeded here. I.e. we are the aliens, and being observed as some sort of experiment