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

#171

Post by thaumasiotes » Sat, Oct 24, 2020, 12:48 AM UTC

Retric wrote: post #154

deeeeplearning wrote: post #76

Earlier quoted context omitted.

Not sure why it was downvoted. Many people have looked into this. https://gtocx.jpl.nasa.gov/gtocx/competition/ Even entire competitions to find optimal colonization methods. Could take 90M years with measly future human tech. Age of Milky Way is 13.5 Billion so even conservatively you could indeed colonize the galaxy many many times over in that time.

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…

> For example, what happens if they first send a probe to verify habitability? Suddenly travel times more than double.

This doesn't seem like a good idea if their method of traveling is generation ships. What would be the point?

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

#172

Post by tzs » Sat, Oct 24, 2020, 12:51 AM UTC

jcranmer wrote: post #155

tzs wrote: post #137

Earlier quoted context omitted.

> It could take millions if years of technological civilization to produce a machine capable of sustaining life for the hundreds of thousands of years necessary for interstellar travel. For a generation ship, are you referring to all the machinery that can maintain a balanced ecosystem of plants and animals and humans in order to provide food for the people during the trip to the new planet, and to make all the thing…

> a sphere with a radius of 24.4 meters A more human-sized comparison is "100 average single-family homes in the US, all filled to the brim with rice". Or 60 ISSes, all filled completely with rice. Per person. And this is volume, not taking into account the weight of rice. Minimum sustainable population size seems to be about 100 people, so consider how large a ship you'd need just to fit all that rice storage.

It sounds ridiculously large when you put it as 100 average single family homes filled to the brim (I get about 50, BTW, using 2623 sq ft with 9 ft ceilings for the average single family home).

On the other hand, it is under two Mount Palomar observatory domes full.

I'm assuming anyone building a generation ship is going to build it in space, not build it on a planet's surface and then try to launch it, so size is not really going to be an issue.

The big engineering issue will be propulsion. We don't have anything now that could drive such a ship. My guess is that this is either something we'll have within the next couple hundred years or we'll never have it.

I'm assuming that by the time you want to build this kind of ship, you've gotten raising people from frozen embryos or frozen eggs and sperm perfected, and that is where most replacement crew would come from. That should greatly reduce the crew size needed.

I think we'll be able to handle the biological side of this within a hundred years, with a good chance of it being quite a bit sooner than that.

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

#173

Post by bena » Sat, Oct 24, 2020, 1:01 AM UTC

ben_w wrote: post #115

bena wrote: post #83

Earlier quoted context omitted.

Yes, I know the paradox. It's simple. It's too simple. It has huge assumptions. Namely the assumption that the current problems to colonization can be solved in a cost-effective manner. The longest continuous length of time spent in what limited space flight we have is just under 440 days. Not to mention, all of it was spent in low Earth orbit. Once we go beyond that, we lose all protection from the Earth's magnetosp…

> We can't fake gravity. Yes we can, it’s a standard part of fairground rides. (I’ll agree that the unknowns of space colonisation, and of the automation we’d need to be able to afford the infrastructure to even launch a serious effort, may prevent such colony efforts from happening)

Centrifugal force does mimic gravity but it's not really something we can do at scale or even in space. When we're talking about a generation ship, we're talking about something a little larger than the Gravitron.

Not to mention, they work within Earth's gravity. Take a tube and spin it around you in space, it does nothing to you because there's no other forces working on you. Nothing putting you in the frame of the spinning tube.

Once you lose the Earth, it becomes a lot trickier to tie you to a frame of reference. Nothing we can make has the mass necessary.

The best we could likely do is accelerate a ship at 1G. But that has problems, because about halfway through your journey, you have to start decelerating. And there's also the issue of turning.

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

#174

Post by tzs » Sat, Oct 24, 2020, 1:02 AM UTC

natechols wrote: post #164

tzs wrote: post #137

Earlier quoted context omitted.

> It could take millions if years of technological civilization to produce a machine capable of sustaining life for the hundreds of thousands of years necessary for interstellar travel. For a generation ship, are you referring to all the machinery that can maintain a balanced ecosystem of plants and animals and humans in order to provide food for the people during the trip to the new planet, and to make all the thing…

I'm always fascinated in the assumptions underlying some of these proposals, and how little thought they've given to the problem. For example, the complete disregard for the lives or autonomy of the "replacement crew", who are effectively treated as a consumable resource starting from childhood. Science fiction set on generation ships tends to be extremely gloomy for good reason.

The issue of crew as consumable resource is interesting.

It's particularly interesting I think because now that you've brought it up, it seems to me there is a similar issue with much Earthly colonization or frontier expansion, and I've never seen it mentioned.

For example, anyone who left England to start or join a New World colony early on, when settlements were far apart and it was a struggle for each to survive, was entering an environment where their children would have a much harder, much more constrained life than they could have had back in England.

Were there debates back then about the morality of moving somewhere where you descendants, possibly for generations, would have harder lives than if you stayed where you are?

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

#175

Post by krapp » Sat, Oct 24, 2020, 1:16 AM UTC

zabardasth wrote: post #168

krapp wrote: post #88

Earlier quoted context omitted.

Angelic doesn't imply good, just being sufficiently advanced enough to seem like magic (to use another Clarke quote.) Demons are technically angels after all.

> And she took on another heart—no longer minded toward earthly things—but ecstatically in the angelic dialect, sending up a hymn to God in accord with the style of the angels. And as she spoke ecstatically, she allowed “The Spirit” to be on her garment. It seems that speaking to one would be quite a terrifying experience, especially if one were speaking in tongues.

When angels are described in the Bible, it's often in strange and abstract terms, beings with multiple faces, legs made of burning bronze, eyes where eyes shouldn't be, etc. As if the writer was having difficulty comprehending what they were seeing,much less finding language for it. And the first thing angels do when they encounter humans is tell them not to be afraid, because of course the logical and proper reaction to skyscraper-sized interlocking, burning, eye-covered wheels with multi-faced, multi-winged beings in the middle is bowel evacuating terror.

And of course, many of Lovecraft's eldritch horrors were simply aliens that were so alien that the mere sight of them broke human minds, and that were no more concerned for humanity than humanity is for a particular anthill.

That's probably what an actual encounter with an alien is going to be like for us. We'll try to understand why a living infinite-dimensional hypersphere made of flesh made of time whose eyes are our eyes all at once just showed up and "unfolded" our sun into a non-Euclidean shape we can't even describe mathematically without being driven slowly to madness, while it won't even know we were there.

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

#176

Post by vl » Sat, Oct 24, 2020, 1:19 AM UTC

dyingkneepad wrote: post #117

vl wrote: post #112

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. Humans evolved specifically to live on Earth, to live somewhere else, they need to be severely altered. Now you just seeded civilization of another species, that might turn out to be confrontational or outright hostile. Why would you do that? Too see how well this works…

> Basically there is not need and motivation for humans to colonize anything outside the Earth. Our current gas emissions would disagree. Also, asteroids, gamma ray bursts, curiosity, sheer ambition, etc, etc. The thing is: we don't need to convince all of mankind to colonize another planet. All it takes is a few people. Crazy rich Mr. Musk is one example. He may not be able to achieve it, but maybe all we need is a…

While personal ambition is commendable, realistically for inter-stellar colonization this has to be planet-wide project.

> suddenly we'll be in other planets.

Who is “we” in this case, how does it affect you and me? (The point being is that such long-term projects are beyond current society capabilities)

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

#177

Post by natechols » Sat, Oct 24, 2020, 1:20 AM UTC

tzs wrote: post #174

natechols wrote: post #164

Earlier quoted context omitted.

I'm always fascinated in the assumptions underlying some of these proposals, and how little thought they've given to the problem. For example, the complete disregard for the lives or autonomy of the "replacement crew", who are effectively treated as a consumable resource starting from childhood. Science fiction set on generation ships tends to be extremely gloomy for good reason.

The issue of crew as consumable resource is interesting. It's particularly interesting I think because now that you've brought it up, it seems to me there is a similar issue with much Earthly colonization or frontier expansion, and I've never seen it mentioned. For example, anyone who left England to start or join a New World colony early on, when settlements were far apart and it was a struggle for each to survive,…

17th century American settlers were fleeing an environment where the child mortality rate was at least 1/3rd even for the upper classes, nearly all land and wealth was controlled by inbred gangsters, and the penalties for petty theft or incorrect religious worship included public hanging. From that perspective, the risks associated with colonization may have seemed much more attractive than the best-case scenario of spending several more decades of poverty in the same village. At least once you were in America, voting with your feet and moving west was always an option, something that was already recognized by 19th-century European socialists as a unique factor in the development of the US economy.

Of course I'm also assuming that the majority of the colonists were not only dirt poor, but also ignorant and uneducated and shamelessly lied to by the promoters of colonization.

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

#178

Post by zimpenfish » Sat, Oct 24, 2020, 1:35 AM UTC

neuronic wrote: post #142

deeeeplearning wrote: post #72

Earlier quoted context omitted.

Using some rough numbers like the distance between NYC and London vs the distance from Earth to Alpha Centauri the equivalent would be saying that Voyager 1 is about 1.8 Miles into a 3470 mile journey (from NYC to London).

Maybe also mentioned that it managed those 1.8 miles travelling since the 70s...

Travelling 8x faster than the fastest vehicle we've made, too (the X-15 managed 2km/s; the Voyagers are doing around 16km/s)

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

#179

Post by dghughes » Sat, Oct 24, 2020, 1:50 AM UTC

ineedasername wrote: post #170

That headline should probably be "at" 1k stars. Being "on" the star would make for a much more interesting story though.

Could Life Evolve Inside Stars?

Cosmic strings and magnetic monopoles coming together as the "DNA" of this theorized exotic life form.

https://www.youtube.com/watch?v=XNK5oahmw3I&ab_channel=PBSSp...

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

#180

Post by greggman3 » Sat, Oct 24, 2020, 1:52 AM UTC

According to a talk I went to we don't have the tech to pick up our own signals. In other words, we started putting out singnals ~100 years ago with radio and then TV. If we were even at Alpha Centuri, our current equipment could not pick up those radio/tv signals.