Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

A Lonely Universe

inference-review.com

Post reply on HN
Print view View original

121–130 of 210 posts

Re: A Lonely Universe

#121

Post by Thiez »

ncmncm wrote: post #92
brabel wrote: post #85

Earlier quoted context omitted.

I think we are in a relatively safe corner of the galaxy though... IIRC there's no cosmical existential threat we know of within the next billion years or so, and the kind of cataclism you're talking about would be the kind of thing we should already be able to predict millions of years in advance.

Sol orbits the galaxy independently of all other bodies. We don't know where most of the magnetars are, never mind their orbits, which are anyway unpredictable. (The nearest we know of is ~5kly? away. Or more, or less.) We don't know where any but two of the black holes are, although there must be a billion or more. Less than ten million years ago we flew into a dust cloud left over from a recent supernova. We could…

And what exactly would our hypothetical descendents do there, in the middle of nowhere with no star, no planets, and no energy?

Re: A Lonely Universe

#122

Post by jason-phillips »

wruza wrote: post #94
Causality1 wrote: post #2

Either intelligent life is rare in the universe or there's something that happens to it that prevents it from what we envision as the future of our own species, i.e., colonizing and spreading among planets. Maybe 99.99% of species ruin their own climate before getting off-world. Maybe they all decide it's happier living as hunter-gatherers. Unless we're alone, there is some fate that's common to all intelligences and…

Expansion is a property of k>1 reproduction. We could make a sustainable happy civilization even on this dirty planet, if not our biological drive to multiply and eat all gifted to us resources with time. My bets are not on climate ops or hunting-gathering for mature civilizations, but simply on k~=1, the simplest form of existence that brings more value with time instead of more size.

In my opinion this comment brings the discussion full circle, from reasoning the difficulties of intergalactic travel back to the quandary of our home.

Re: A Lonely Universe

#123

Post by pfdietz »

foobarian wrote: post #120
pfdietz wrote: post #118

Earlier quoted context omitted.

A super earth would require exponentially more energy with chemical rockets, due to that darn rocket equation. Fortunately, Earth isn't that bad.

> A super earth would require exponentially more Polynomially, right?

No, exponentially. I used that word precisely, because the mass ratio in the rocket equation is exponential in (delta V)/(exhaust velocity).

Re: A Lonely Universe

#124

Post by rel2thr »

Causality1 wrote: post #2

Either intelligent life is rare in the universe or there's something that happens to it that prevents it from what we envision as the future of our own species, i.e., colonizing and spreading among planets. Maybe 99.99% of species ruin their own climate before getting off-world. Maybe they all decide it's happier living as hunter-gatherers. Unless we're alone, there is some fate that's common to all intelligences and…

It’s pretty rare on earth too, 10 million species but only 1 has space flight and the others aren’t anywhere close to developing it!

Re: A Lonely Universe

#125

Post by pfdietz »

brabel wrote: post #84
Animats wrote: post #61

Earlier quoted context omitted.

Everything is simply too far apart. That's very likely. There are only two known systems with possibly habitable planets within 40 light years.

Not to mention that when we talk about other galaxies, then distances are on a whole different scale again. While travelling to other stars takes "only" a few thousand years, to go to another galaxy you might need several hundred million years with any technology we can currently even imagine. Even if intelligent life is rare enough that it only appears once on a single galaxy every several billion years, we're still…

We can achieve relativistic speeds with technologies we can imagine (specifically, laser light sails). This would require just millions of years to get to M-31, for example (which is 2 million light years away).

Re: A Lonely Universe

#126

Post by folbec »

abhishekjha wrote: post #51
fleddr wrote: post #15

Earlier quoted context omitted.

Exactly. For an optimist, we might one day colonize Mars. Next, getting out of our solar system is incredibly unlikely as the first habitable destination in our own galaxy is just so far away. Say we stretch our optimism and do make it. Now the colonization of the Milky Way starts. It's a 100,000 light years to the other end. You'd be a completely different species by the time you arrive. Say you achieve that (you wo…

>The only path would be to become a machine instead, slowly replacing biological parts with superior silicone. Until nothing biological remains. Reproduction has to be intact. But I do agree. We as a species are not fit to these interstellar or intergalactic travels. It has to be dominantly machines.

C. Stross - Saturn's Children.

https://www.amazon.com/Saturns-Children-Freyaverse-Charles-S...

Re: A Lonely Universe

#127

Post by saiya-jin »

shagie wrote: post #69
pfdietz wrote: post #57

Earlier quoted context omitted.

It actually doesn't require THAT much energy to get into orbit. The energy of a kilogram of mass in low earth orbit is about 9 kWh, although rockets will use a bit more than that (not enormously more, though). Fuel cost remains a minor fraction of launch cost, even with Falcon 9. In comparison, the best aluminum plants in the world use 13 kWh to make a kilogram of aluminum. Yet no one says aluminum is out of reach be…

An interesting problem is "how much energy would it take to launch from a super-earth?" https://www.space.com/40375-super-earth-exoplanets-hard-alie... > To launch the equivalent of an Apollo moon mission, a rocket on a super-Earth would need to have a mass of about 440,000 tons (400,000 metric tons), due to fuel requirements, the study said. That's on the order of the mass of the Great Pyramid of Giza in Egypt. We m…

I agree with rare earth theory too, but even with it, the observable universe is so huge that even those tiny fractions of various probabilities should at the end materialize on a massive scale.

And its not like with higher G or some other singular aspect moving into more challenging territory, everything becomes suddenly impossible. Think about how many obstacles mankind could conquer in a relatively short amount of time, say a million years.

Re: A Lonely Universe

#128

Post by jeremyjh »

Thiez wrote: post #121
ncmncm wrote: post #92

Earlier quoted context omitted.

Sol orbits the galaxy independently of all other bodies. We don't know where most of the magnetars are, never mind their orbits, which are anyway unpredictable. (The nearest we know of is ~5kly? away. Or more, or less.) We don't know where any but two of the black holes are, although there must be a billion or more. Less than ten million years ago we flew into a dust cloud left over from a recent supernova. We could…

And what exactly would our hypothetical descendents do there, in the middle of nowhere with no star, no planets, and no energy?

There are stars that are far from everything else and off-axis. There are even stars that get ejected from the galaxy all-together.

Re: A Lonely Universe

#129

Post by Tepix »

Animats wrote: post #61
lubujackson wrote: post #24

Earlier quoted context omitted.

The third option is that everything is simply too far apart and any detectible transmissions are either too faint or buried behind all those massive fusion furnaces. For instance, if our best Earth tech was pointed at Earth from a distant star, how far away would we be able to detect our own traces of life? We know that life is "a little rare" at least, but there is a huge range of rarity where life is everywhere acr…

Everything is simply too far apart. That's very likely. There are only two known systems with possibly habitable planets within 40 light years.

We have yet to discover an earth-like planet with an earth-like orbital period. They are unlikely to be rare, they are merely hard to detect with our current technology.

Re: A Lonely Universe

#130

Post by vmoore »

Maybe it's just aswell planets with life are unimaginably far apart. What if some virulent pathogen got loose and got onto other (close) planets? Earth is going through a global pandemic now. If we make close contact with advanced intelligences we could pass on diseases to them that would contaminate their species. In a sense the long distance of relative planets acts as a quarantine!
Post reply on HN