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Comment by 7thaccount | Hacker News Reader

I saw something recently that one explanation is that we're in a cosmic void. Sure the milky way is big, but we're still exposed to a fraction of the worlds that a non-void area would be.

Of course there are 80,000 other explanations that are also fascinating. A wonderful subject.

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For me what makes most sense is that we're relatively early in cosmic history. You need enough heavy (and diverse!) elements to be able to support life/civilization and you won't get that from early stars.

Most probably yes, I mean we only have few generation of stars actually producing heavy elements enough to see what we see ie on Earth, not just some hydrogen & helium ball.

Also most probably there isnt any way to travel back in time, since we would most probably be eliminated at the seed to not compete for resources or avoid aggression. For all wonderful things mankind did and does, we are still deeply flawed and highly emotional primitive beings, and we may kill ourselves due to this.

The real tragedy, we're taking so many others with us.

On cosmic scales of time, theres no reason to assume spacefaring humans would remotely resemble us in any recognizable way. Imo especially their minds, they’d almost certainly have augmented and modified their thinking drastically.

And earth has been around for 1/3rd of the current age of the universe. As far as things go it's pretty old.

Add to that that we probably aren't as "normal" as we initially believed. A solar system with small rocky planets on the inside and big gas giants on the outside seems to be the exception and was very important for earth's development. Then there's the above mentioned "void" we are in, and probably other things we don't realize yet.

There's a really good case that we are among the earliest spacefaring civilizations

> A solar system with small rocky planets on the inside and big gas giants on the outside seems to be the exception

Is this actually the case?

They haven't cited a source or their reasoning, I would guess they mean "seems to be an exception by observation"

Emphasis on "observation".

Currently we infer planets that orbit stars that are extremely distant by starlight dipping in intensity .. this is a method that works better with larger planets and that skews the results of observing distant planets.

We have observed some small rocky earth like planets IIRC but these are rare, observations perhaps due more to luck in looking than frequency of existence.

This is the crux of the problem; does the distribution of planets we observe match the distribution of planets that exist?

Well don't forget that Earth had it's reset button smashed 66 million years ago. Let's say another world started out at the same as we did but never encountered such a cataclysm. Even if they took an additional 65 million years to develop, they'd still be a million years older than us.

The KT boundary is hardly a "reset button smashed". Yes, it was a mass extinction event, but these things happen. The products of billions of years of evolution survived, even if megafauna had a setback. Evolution spent billions of years figuring out basic things like the genetic code, sexual reproduction, and mitochondria. All these technologies survived the KT boundary. Complex multicellular life emerged only about 560 million years ago (after single-celled life had been around for billions of years). The implication is that the early innovations in life (ribosomes, etc.) were "harder" than later ones involving eyes, brains, and so on.

A "reset button" would be more like the impact that created the moon: ramming a Mars-sized body into Earth turns Earth into a magma ocean. Nothing survives that. By comparison, the KT boundary asteroid is small potatoes.

I hadn’t considered that angle of things before. It also brings up the opposite idea, I wonder if the over abundance of heavy elements in an old universe could reduce the likeliness of life being able to form due to the toxicity or higher levels of background radiation.

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