“Elements heavier than iron, up to bismuth, are primarily produced via the s-process (slow neutron capture) in low to medium-mass stars during their later evolutionary stages.

The remaining and heaviest elements (beyond iron and bismuth) are formed through explosive events: core-collapse supernovae generate elements between neon and nickel, while the r-process (rapid neutron capture) in supernovae and, predominantly, neutron star mergers creates elements like uranium and thorium, dispersing them into the interstellar medium for planetary formation.”

From https://www.astronomy.com/science/the-universes-guide-to-cre...

I think you're right that heavier elements can be made, it's just energy negative to do so. But without a nova they would never leave the inside of the star to find their way into a new planet.

> But also why did the Sun form at all?

I don't understand the question. There must have been a cloud of gas big and dense enough to provide the mass for the solar system.

Once that exists gravity does the rest, right?

> all the uranium we have on Earth came from such an event

That must mean the Sun also has its fair share of that Uranium? Or maybe more of it, since the heavy elements were more drawn to the center of the solar system?

Surely someone has proposed the existence of a civilization forming from <=iron and making the heavier elements themselves? Seems far fetched but you have quite a bit of time to play with there.

> So this all had to happen sufficiently close to the Sun and that material had to be captured in the Sun's protoplanetary disc. We needed the right combination of elements to form a protective magnetic field and produce enough but not too much heat.

any idea how close? like 10s of light years or what?

> It's kind of why I think sentient life is incredibly rare.

They just found the building blocks of life in asteroid Bennu:

https://science.nasa.gov/mission/osiris-rex/

https://physicsworld.com/a/components-of-rna-among-lifes-bui...

“So far we have not seen any evidence for a preferred chirality,” (Dan) Glavin says (important for understanding why amino acids on Earth seem to all be left-handed):

https://physicsworld.com/a/asteroid-bennu-contains-the-stuff...

Life is probably abundant everywhere in the universe. Also, evolution seems to spring up everywhere, in any system of sufficiently advanced complexity, regardless of what substrate it operates on. So I think that we'll start seeing life-like emergent behavior in computing, especially quantum computing, in the next 5-10 years.

So the question becomes: what great filter (in the sense of the Drake equation and Fermi's paradox) causes life as we know it to go dark or wipe itself out just after it achieves sentience?

Well, we're finding out the answer right now. Life probably merges with AI and moves into what could be thought of as another dimension. Where time moves, say, a million times faster than our wall clock time, so that it lives out lifetimes in a matter of seconds. Life everywhere that managed to survive probably ascended when it entered the matrix. So that by now, after billions of years since the first life did this and learned all of the answers, we're considered so primitive that Earth is just a zoo for aliens.

Or to rephrase, omnipotent consciousness probably gets bored and drops out of the matrix periodically to experience mortal life in places like Earth. So simulation theory probably isn't real, but divine intervention might be.

>It's kind of why I think sentient life is incredibly rare.

Agreed. The universe is big, but combinatorics are bigger.

I'd be disappointed but ultimately unsurprised if an all-knowing oracle said it has only happened once in the history of the universe. My follow up question, of course, would be whether or not it happened on Earth.

And yet, inevitable. That’s why a simulation of the universe would be a secure way of creating AGI in the true sense. All depends on: can you find an algorithm that simulates quantum physics efficiently, or, can you make a quantum computer with sufficiently many qbits?

Incredibly rare X maybe a trillion planets(oids) in our galaxy X maybe a trillion galaxies in whole universe may change the outcome a bit.

Of course if speed of light is the hard unavoidable limit it doesnt matter now or for next few trillions of years. Eventually though, if it will keep expanding, the only important thing in universe will be energy. Species that will grok that first may decide to not share and take it all for themselves. Although sustainability of some empire over 10^10^10^10 years and further... its something even my otherwide vivid imagination can't concieve.