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Comment by aardvark179 | Hacker News Reader

You seem to be conflating life, multicellular life, and intelligent life. Life appears to have developed on Earth pretty quickly, multicellular life took a long time to appear, and we are only aware of one species that developed civilisation building capabilities.

Life might be very common, but intelligent life still be incrediblY rare.

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It depends what you mean by "civilization building". I think we gloss over that a bit too much. We're not the largest population, not the largest total mass, not the only one that builds large structures. We're the only one that sent stuff outside of Earth, yes, and a few other things. But discussing the definition is itself interesting

Human civilisation means intelligence and memory are collective, externalised, persistent, communicable. There's also a layer of symbolic abstraction (science and math) which makes it possible to predict useful consequences with some precision.

Individuals die but their inventions and insights remain. Individuals can also specialise, which is a kind of civilisational divide and conquer strategy.

Most animals don't have that. Some do train their young to a limited extent, but without writing the knowledge doesn't persist. And without abstraction it only evolves extremely slowly, if at all.

They have to reinvent the wheel over and over, which means they never invent the wheel at all.

We actually have this problem with politics and relationships. We keep making the same mistakes because the humanities provide some limited memory, but there's no symbolic abstraction and prediction - just story telling, which is far less effective.

Bonus points: I often wonder if there's a level of complexity beyond our kind of intelligence, and what it might look like. Abstraction of abstraction would be meta-learning - symbolic systems that manipulate the creation and distribution of civilisational learning.

AI seems to be heading in that direction.

There may be further levels, but we can't imagine them. We could be embedded in them and we wouldn't see them for what they are.

If you include our crops and livestock then our civilisation has about half the land biomass. 38% of the earths land is farmland. (We use the richest parts as farmland) https://www.ncesc.com/geographic-faq/what-percentage-of-land...

Another 34% is Forrest, much of which is managed for logging.

We are capable of rapidly changing chemical composition of atmosphere, which may be noticeable even at our technological level.

Plenty of lifeforms have changed the composition of the atmosphere. At faster rates than we are changing it now.

The only similar example I can think of is when, roughly 2400 million years ago (during the Paleoproterozoic iirc), the ancestors of cyanobacteria poisoned their atmosphere by overproducing oxygen which resulted in an extinction event. But that whole process still took somewhere in the order of millions of years to complete I believe.

> But that whole process still took somewhere in the order of millions of years to complete I believe.

The geological evidence is that that oxygen build-up first had to exhaust things that took the reactive oxygen out of the air and water. Iron oxide was laid down as huge deposits of "banded iron ore" The great rust. (1)

This is hard to get an exact number on, but as far as I know, it is estimated to have taken at least 500 million years.

And then oxygen increased again, a billion years later (2)

It was not fast. It was measured in 100 million year ticks.

1) https://en.wikipedia.org/wiki/Great_Oxidation_Event#Banded_i...

2) https://en.wikipedia.org/wiki/Neoproterozoic_oxygenation_eve...

Faster? Do you have an example? What species can add 10^12 tons of any chemical in just few hundred years?

There were geological events and asteroid impacts that may result in more dramatic changes, but their signatures will be different.

Indeed. We might finally start getting some real estimates for those factors in the Drake Equation.

>we are only aware of one species that developed civilization building capabilities.

well, the first one just doesn't leave any chance for any other one.

>Life might be very common, but intelligent life still be incrediblY rare.

the time period between big ape and nuclear bomb is extremely short - few millions years. In a hundred or a thousand - doesn't really matter - years we'll be an interstellar species or may be we destroy ourselves by Covid-2319. The point is that complexity develops exponentially and tremendous changes are happening in an extremely a short period of time - i.e. if life has 4B years to develop when it most probably has 4.01B years to develop civilization.

Unlikely we will ever be interstellar. The technology involved is speculative and the physics barriers needed to be surpassed are impossible and not well understood.

To reach another star by the laws of physics involves many human lifetimes and that’s just the nearest star.

That in itself makes it more likely that we will never be interstellar.

Slow but plausible starships can be designed with 1960s technology. The obstacle is not the technology but the scale of the effort, a problem that could be solved by extension of civilization into the solar system with much larger populations.

https://galileo.phys.virginia.edu/classes/109.jvn.spring00/n...

Humanity will never put effort into this. We don’t have the technology yet but yes we can develop it but doing this is harder than building a bridge across the ocean between Asia and the US.

That bridge is also within our technological capacity. But it’s not happening period.

That depends on the scale of human society, doesn't it? Grow the population in the solar system enough and it becomes a smaller fraction of gross output than many trivial and frivolous things are today.

I'm arguing here that if non-interstellar space colonization is possible, interstellar colonization is a natural and feasible extension. You might argue that even colonization in the solar system will not occur, and I admit that's a defensible position.

>The technology involved is speculative and the physics barriers needed to be surpassed are impossible and not well understood.

we can build with today's tech - classic nuclear reactor plus ion drive - a 3 stage ship reaching 1000km/s, 1200 years to the closest star. Once we get to fusion, we'll be able to improve that speed a small order of magnitude.

>To reach another star by the laws of physics involves many human lifetimes and that’s just the nearest star. >That in itself makes it more likely that we will never be interstellar.

That is exactly what makes it _inter_stellar:) We'll have generations - 10-15 to the nearest star with the current tech mentioned above - of people living their lives on those ships. Living on a planet will become a strange thing for them.

I think in 10-20 years, once launching into LEO becomes cheap with Starship, companies, universities and wealthy individuals will be launching solar + ion drive and nuclear + ion to all the places in the Solar System and some automated probes - beyond.

"Roundtrip Interstellar Travel Using Laser-Pushed Lightsails"

https://ia800108.us.archive.org/view_archive.php?archive=/24...

We can disperse intelligent machines. Possibly with the ability to regenerate biological life.

Intelligent life most like arose from the extinction level events that wiped out less intelligent super predators. This gave those who are far weaker but with higher brain capacity the chance to express their genetic variations.

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