Aliens on 1k nearby stars could see us, new study suggests • Hacker News Board

Re: Aliens on 1k nearby stars could see us, new study suggests

#201

Post by mylons » Sat, Oct 24, 2020, 4:32 AM UTC

Retric wrote: post #185

mylons wrote: post #169

Earlier quoted context omitted.

If you used the Von Neumann machine approach wouldn’t it not really matter if the planet was habitable or not?

Let’s assume your sending a Von Neumann probe to prep the way for your ship. Now it shows up and does whatever it needs to and then sends an everything is ready signal before you send your generation ship. I mean sure you could in theory send out an endlessly replicating probe that keeps going to other star systems, but that’s even more risky.

What’s risky about it? The risk seems in them overtaking the entire galaxy more than anything, no?

Re: Aliens on 1k nearby stars could see us, new study suggests

#202

Post by eloff » Sat, Oct 24, 2020, 4:38 AM UTC

e12e wrote: post #99

eloff wrote: post #74

Earlier quoted context omitted.

I don't know why this got down-voted. The milky way is 100K light years across. It's 13.5 billion years old. It's entirely possible to blanket the whole galaxy with probes, without even getting into self replicating probes.

You have to make an assumption about speed - it certainly won't be more than a tiny fraction light speed. Eg voyager appear to travel now at less than 0.00006 c (16 km/s). Than turns 100k light years into ballpark 150 M year journey (no it doesn't its 1.8 bn years as mentioned in reply) . Still possible to cross 10.000 times - but that would be a straight line. I suspect the distances will grow somewhat fractally if…

To imagine that voyager technology will define the maximum velocity of interstellar travel, a thousand years from now, ten thousand, a million, etc is short sighted. Maybe we never can exceed light speed, but we could get up to a reasonable percentage of it.

Re: Aliens on 1k nearby stars could see us, new study suggests

#203

Post by chordalkeyboard » Sat, Oct 24, 2020, 4:42 AM UTC

ceejayoz wrote: post #125

chordalkeyboard wrote: post #98

Earlier quoted context omitted.

If planets in the “goldilocks zone” are extremely rare and they want to “terraform” (xenoform?) those planets then thats a motivation.

1. That seems very unlikely, from what we've found so far. We'll know more as things like the JWST come online, but right now it seems like planets of all sorts are everywhere . 2. Any civilization capable of interstellar travel is likely not to care all that much about a narrow band of natural habitability. They've already solved harder problems.

I'm not sure its given that a civilization that has technology for interstellar travel is going to consider a planet that is suitable for life with little work to be roughly equivalent to a planet that is suitable for life with a lot of work. Its equally likely that they would be economical with their resources and consider a planet that is closer to the desired end state to be much more valuable than a planet that is much further from the end state.

Re: Aliens on 1k nearby stars could see us, new study suggests

#204

Post by SturgeonsLaw » Sat, Oct 24, 2020, 5:16 AM UTC

bena wrote: post #105

deeeeplearning wrote: post #91

Earlier quoted context omitted.

You talk like this is all expected to be done by 21st century humans when in reality if there were civilizations out there capable of doing this colonization they would likely be millions of years our elders and its incredibly foolish to try to guess their intentions or the capabilities of their technology. Your view is painfully anthropocentric. Just to add, there are plenty of valid criticisms or plausible solution…

You talk like this is all a forgone conclusion. Technology is not magic. Time is not a salve that solves all issues. You say that my view is "painfully anthropocentric", but how? It seems your only response is "but aliens". That is not good enough. You want to say that it is foolish of me to try and guess their intentions and capabilities, but that's what the paradox does as well. It assumes their intentions are to c…

> You say that my view is "painfully anthropocentric", but how?

I'm not OP but the idea of thinking in terms of "return on investment" strikes me as very 20th century humanity.

Who's to say a future society wouldn't consider finding another civilisation to be a massive ROI? Or that a post-scarcity society living under Fully Automated Luxury Gay Space Communism would even care about a return, instead of just doing things because they care to do them?

Re: Aliens on 1k nearby stars could see us, new study suggests

#205

Post by tomerico » Sat, Oct 24, 2020, 5:16 AM UTC

rsynnott wrote: post #143

tsimionescu wrote: post #133

Earlier quoted context omitted.

> My personal opinion is that life under early Earthlike conditions was/is almost a guarantee. There is compelling evidence that life already existed in and survived the Late Heavy Bombardment- that's very early in our planet's history. If it was truly a rare event that sparked things off, I would expect it to have occurred much later in the planet's history. That is valid of course, but in the absence of evidence of…

Hmm, I'm not sure that that's correct. If you build an apartment block and it catches fire the week afterwards, then it's perhaps not reasonable to expect that if you build another one to exactly the same design it will never catch fire. At that point you might want to be reviewing your wiring plans. That life showed up so early says... something. If life showing up was so fantastically difficult, we would arguably e…

Well, if it did show up in the late heavy bombardment, it could have also arrived from outer space.

Re: Aliens on 1k nearby stars could see us, new study suggests

#206

Post by birdyrooster » Sat, Oct 24, 2020, 5:39 AM UTC

"on nearby stars" okay

Re: Aliens on 1k nearby stars could see us, new study suggests

#207

Post by tsimionescu » Sat, Oct 24, 2020, 6:49 AM UTC

rsynnott wrote: post #143

tsimionescu wrote: post #133

Earlier quoted context omitted.

> My personal opinion is that life under early Earthlike conditions was/is almost a guarantee. There is compelling evidence that life already existed in and survived the Late Heavy Bombardment- that's very early in our planet's history. If it was truly a rare event that sparked things off, I would expect it to have occurred much later in the planet's history. That is valid of course, but in the absence of evidence of…

Hmm, I'm not sure that that's correct. If you build an apartment block and it catches fire the week afterwards, then it's perhaps not reasonable to expect that if you build another one to exactly the same design it will never catch fire. At that point you might want to be reviewing your wiring plans. That life showed up so early says... something. If life showing up was so fantastically difficult, we would arguably e…

Sure, but if you look at an extremely old building and find signs of fire only from its very early age, it's somewhat strange to say that it was very likely to catch fire.

Re: Aliens on 1k nearby stars could see us, new study suggests

#208

Post by Retric » Sat, Oct 24, 2020, 7:05 AM UTC

mylons wrote: post #201

Retric wrote: post #185

Earlier quoted context omitted.

Let’s assume your sending a Von Neumann probe to prep the way for your ship. Now it shows up and does whatever it needs to and then sends an everything is ready signal before you send your generation ship. I mean sure you could in theory send out an endlessly replicating probe that keeps going to other star systems, but that’s even more risky.

What’s risky about it? The risk seems in them overtaking the entire galaxy more than anything, no?

Building something with zero possibility of change across millions of years is difficult. Something as simple as reproducing endlessly means they end up wasting enormous amounts of resources. But, you also risk things like probes that don’t slow down and hit one of your planets.

Re: Aliens on 1k nearby stars could see us, new study suggests

#209

Post by s5300 » Sat, Oct 24, 2020, 7:28 AM UTC

root_axis wrote: post #196

skissane wrote: post #123

Earlier quoted context omitted.

> Basically there is not need and motivation for humans to colonize anything outside the Earth. It's just too far, too expensive and too uncomfortable. There is definitely motivation. Some people want to colonise Mars. Not everybody, but likely enough people to make it happen. Elon Musk wants to make it happen, and while there is no guarantee he'll get his wish, I think he has a decent chance of succeeding. And estab…

It's certainly possible that we might visit Mars, but colonizing it just isn't possible within the foreseeable future, certainly not within Musk's lifetime. We're not even close to having the technology necessary to survive that kind of journey and the engineering, logistics and medical science required to actually start a colony is far beyond anything we are currently capable of.

Musk has touched on the fact that it's nearly guaranteed to not be possible within his lifetime.

This is one of the reasons (he's spoken of) that he's having a decent amount of kids and also doing things like Neuralink.

Re: Aliens on 1k nearby stars could see us, new study suggests

#210

Post by Retric » Sat, Oct 24, 2020, 7:40 AM UTC

sliken wrote: post #189

Retric wrote: post #154

Earlier quoted context omitted.

The Milky Way lacked rocky planets early on, making that 12.5 Billion year age largely meaningless. Which is just one of many bad assumptions in how people do these calculations. At a minimum you don’t get a straight path from A to B. Assuming any kind of limitation in distance traveled and your at the mercy of the distribution of whatever resource you need. Aka need rocky planets with liquid water, that’s likely goi…

One effect not considered in early considerations was the differential radial speed. So even the ability to seed planets 10 light years closer or further from the galactic core over a few 100M years results in expansion much more quickly than earlier models.

If you’re talking 10 light year colonization jumps that takes very deliberate and resource intensive expansion efforts. If you instead model things assuming generation ships as harvesting kepler Belt objects, moving between stars only incidentally or as local resources are exhausted. And only occasionally reproducing. The relative motion between stars becomes the primary driver of net expansion, and that’s quite slow.