The complexity of our current civilization. It is truly inconceivable. Let's take a widely-used, complex software package, such as MS Windows - it alone is inconceivably complex, and, on the grand scale of civilization, it's just a speck of dust.

Also, our ability to keep this inconceviably complex system in a relatively stable state (for now...) is also mind blowing.

The apparent immutability of geography in human time, except when you look "harder"

A case in point is the recent piece on the megaflood of the Mediterranean sea: it may well have entirely filled in a matter of months, from initial breach.

Alternatively I am in awe of deep geological time. Sandstone takes a long time. Folding takes a long time. The plasticity of stone under force, heat and time.

I vividly remember backpacking through Painted Desert [1] in Arizona, by far the quietest place I've ever been (and you can viscerally feel it's because of a lack of life), and repeatedly remembering the visitor center exhibits talking about how it all used to be a lush forest.

[1] Scroll down towards the end for some photos => https://kayce.basqu.es/blog/road-trip-2019/

Those strips of intruded rock through granite say it all. Nice trip!

Extinct charismatic megafauna... especially those that were extant in the last hundred thousand years, thinking some of them probably hung out with humans. Man, makes me all sniffly eye'd thinking about a Mowgli story involving a giant sloth.

I want to ride a giant centepeed.

this bad boy?

https://newsy-today.com/giant-centipede-fossil-reveals-bigge...

I know it wouldn't support my 15 stone :-/

Big Trees State Park in Arnold, California is a bit of an unknown gem. You've probably seen pictures of it but not many people go and actually visit. It's full of old growth giant sequoias. Unlike the coastal redwoods which are known for being tall these ones are known for being massive. In other words they are WIDE! And also still quite tall. The open terrain of the park really helps you feel their gargantuan-ness too.

Also, for anyone that hasn't been to either of these places, it is one of those that you simply cannot get the full effect from pictures or videos (same for the Grand Canyon). It truly feels like you've just walked into Tolkien's Middle Earth or something and I am not aware of any comparable place anywhere else on the planet. I highly recommend putting the redwoods and sequoias on your bucket list.

Given the number of Americans on HN and their propensity for using the word "awesome" ad nauseam, I'd say almost everything.

*and Australians too.

How some "simple" rules and (presumably) some randomness shaped up our universe.

How we extract math from nature and find new applications for it.

The internet truly gets more and more amazing the more you contemplate it. I can communicate instantaneously with people all over the world?? We have an encyclopedia that the entire world can contribute to????