Mystery of interstellar visitor 'Oumuamua gets trickier | Hacker News Reader

Mystery of interstellar visitor 'Oumuamua gets trickier

scientificamerican.com

227 pointsOsiris30227 comments

My pet theory (which is not intended to be taken too seriously) is that it is indeed a discarded light sail, and that light sail in particular was used to transport a Von Neumann probe which detached at some point after the object entered our solar system but before we first observed it. This detachment, in addition to leaving the sail tumbling, would have changed its trajectory, meaning our estimation of which direction the object originally came from is incorrect. In any case, the probe is now busy replicating, perhaps on the surface of Mercury. In a few years an army of robots will launch from there and invade the rest of the solar system!

Realistically, though, it's too much of a coincidence that such a probe would first arrive so soon after we gained the ability to conceive of it.

Which forces the logical conclusion that this isn't the first such probe, obviously.

That could only be true if they are intentionally hiding from us, rather than replicating and harvesting the solar system as fast as they can. But personally I have a hard time believing that hyper-intelligent devices would care about avoiding detection by lowly biological organisms like us.

If the mission of the probe is exploration then it doesn’t need to consume all of the resources of a solar system. It just needs enough to make a few copies to reach the nearest handful of stars. If they are using light sails as propulsion they probably need barely anything. I don’t have a hard time believing that an advanced civilization would choose hiding as the default method of exploration. Anything from the dark forest to the prime directive could be used as an argument to do so. I agree with the other comments that it’s fairly likely that our system has had multiple probes pass through. The unlikely event will be when one decides to contact us.

In case there are some younger non Trekkies not sure what the Prime Directive https://en.m.wikipedia.org/wiki/Prime_Directive

While it's entirely possible they'd have a good reason to be stealthy, I don't think it's likely to be anything we've thought of.

The Prime Directive is a mushy human emotional idea, not something that makes any logical sense for a space-faring civilization to follow. If there's any competition out there among space-faring civilizations, none of them are going to tie their hands behind their backs by refusing to touch planets that have native life on them.

And under the Dark Forest, the best way to survive would be to replicate as fast as possible, consuming all available resources. They would want to hide from external, more-powerful civilizations, but they'd have no reason at all to hide from us. Hiding from us would be a strict loss for them, as it means they can't mine Earth for resources.

I’m not sure that reasoning holds up. There’s no reason to believe that “mushy human emotional ideas” are not the norm. There’s no data to support that claim since humanity is the only example we have of intelligence. So for the sake of the argument I’m going to define alien intelligence as similar to human intelligence. I’d also inquire what the point of having a Von Neumann probe consume all of a system would be? It’s not practical to ship the resources anywhere at sub light speed. There’s a limit on the number of probes it would be rational to make in any one system even if you were going for high redundancy. Even use as a weapon would be foolish since there’s a good chance something could go wrong and you’d wind up killing your own systems. Maybe if you were paving the way for a colony but even then you’d only build what you needed to avoid having to constantly maintain the structures until they were useful. The only way I see an exploitive strategy working is if you have FTL travel and if you have that then Von Neumann probes are useless old technology since you would just send a fleet of ships with what you need to get started rather than trying to bootstrap from a single self replicating probe.

Once a civilization is capable of building Von Neumann probes, it would be silly for them not to do so. They are basically free, since they are self-replicating. Of course a civilization is going to want to control and harness as many resources as it possibly can. We may not be able to imagine what they'd want to build out of whole star systems, but I absolutely don't believe that civilization will ever run out of things to build.

If there's any competition between civilizations, then it's even more obvious that each one will be racing to claim any star system that isn't already claimed. But even with no competition, it makes sense to spread rapidly.

If you don't find that intuitively obvious, consider this: In 4.5 billion years, the Milky Way will collide with Andromeda. This presents us with a literal galactic-scale single-turn prisoner's dilemma: If intelligent life exists in Andromeda, they may already be preparing to conquer the Milky Way. If they are, and we don't prepare to fight back, they will obviously win. We won't have any ability to communicate with Andromeda to find out their intentions until it's too late. The earlier we start preparing, the more likely we are to survive.

So if I were a spacefaring civilization in the Milky Way today, I'd be doing everything I could to mobilize every star system in the galaxy in preparation to beat Andromeda. There's just no reason not to...

Andromeda has 3-4 more stars than the milky way; we already lost, should we flee instead?

The odds favor Andromeda, yes. But depending on just how rare intelligent life is, there is some possibility that we have a lucky head start.

As for fleeing: The whole concept of "fleeing" assumes a civilization composed of discrete beings that are expensive to reproduce but can be feasibly transported. The idea of Von Neumann probes is based on a different assumption. The probe itself is very small, maybe only a few pounds, but is designed to expand using the resources at its destination. There probably aren't discrete beings -- computers can freely exchange "memories" over networks which makes them effectively all one big hive mind. The hive mind directly controls everything it builds. Eventually the entire star system -- perhaps the entire galaxy or universe -- becomes effectively one giant intelligent being as all available resources are assimilated.

This civilization would certainly send probes to neighboring galaxies if it has the ability to, but it makes no sense to think about transporting the "inhabitants" (if you can even call them that) of one star system to another en masse.

I wonder whether once a civilisation reached that point, the game theoretical equations around aggressivity and self preservation change significantly to invalidate the dark forest theory.

You should really read The Count to the Eschaton Sequence by John C. Wright. The Cold Equations is another answer to the question you pose.

That's self destructive behavior on a planetary scale. No species that has an instinct or culture to consume all available resources will survive long enough to do it on a galactic scale.

Also, the math doesn't work out in the sense that if a species that had this instinct reached interstellar travel a million years ago the Milky Way galaxy would already have entirely been consumed. That's the Fermi Paradox in a nutshell.

If the species you are describing exists, they must have just started eating the galaxy, because the galaxy would already be eaten in an blink of an eye on the cosmic timeline.

Lets suppose that it takes a ten thousand years to reach a star system and consume it, and the swarm needs the resources of an entire star system just to build 2 more probes.

That means that the number of star systems consumed doubles every ten thousand years. At that rate it takes no more than 50 generations, or half a million years, to consume the entire galaxy.

Note that if the number of probes the Von Neumann swarm builds is more than 2 per star system consumed, this process happens even faster.

Right, this is why I don't actually think the object is a probe: if there is no competition, then a million years from now, we can expect Earth-originating technology will have spread across the galaxy. To imagine that another civilization exists but is no more than a million years ahead of us seems like too much of a coincidence.

>That's self destructive behavior on a planetary scale. No species that has an instinct or culture to consume all available resources will survive long enough to do it on a galactic scale.

Have you ever read Issac Asimov's story "The Gentle Vultures"?

“Of course a civilization is going to want to control and harness as many resources as it possibly can.”

This may be an entirely human-centric assumption. Maybe there are a million civilizations out there living in balance with their local planetary environments, entirely without the expansionist curiosity and destructive drive that leads humans to seriously contemplate things like von Neumann probes?

The desire to survive and expand is not a human trait, it is a natural result of evolution. Any successful evolved species will have this desire because those that don't, don't get anywhere.

Interstellar civilizations are unlikely to be biological, but evolution still applies. All it takes is for one civilization in the whole galaxy to decide to build Von Neumann probes, and they'll have taken control of all unoccupied systems in the galaxy in short order.

Is it? Evolution itself seems like an expansionary process but it doesn't seem to follow that the outcomes of the evolutionary process are expansionary. It seems like many species are evolved to very specific environments like caves or thermal vents that they will stay in for generations if not for thr duration of their existence as species.

Why do you want to "beat Andromeda"? You have your Von Neumann probes, they have their own. Maybe theirs are better. Why do you want yours to beat theirs?

> In 4.5 billion years, the Milky Way will collide with Andromeda. This presents us with a literal galactic-scale single-turn prisoner's dilemma: If intelligent life exists in Andromeda, they may already be preparing to conquer the Milky Way. If they are, and we don't prepare to fight back, they will obviously win. We won't have any ability to communicate with Andromeda to find out their intentions until it's too late. The earlier we start preparing, the more likely we are to survive.

I'm trying to imagine what to do now in preparation for a hostile encounter in 4.5 billion years that isn't already happening organically. By "organically", I mean both "in the course of gradual or natural development" and "w.r.t. living matter", given the time scale.

Do you have ideas?

Consuming all available resources and destroying all competing life doesn’t make sense even for us as the dominant species of a single planet.

What’s the evidence that wholesale environmental destruction is a good idea on a galactic scale if it’s already known to be a terrible idea on a planetary scale?

It's a terrible idea for humans on our planet because we are squishy biological beings whose life is intrinsically dependent on the biosphere around us.

Self-replicating hyper-intelligent artificial beings presumably will be able to redesign themselves to match any target environment.

Note: This is not a moral judgment. I obviously think it would be awful if some AI gray goo consumed the universe and wiped out all the unique forms of life. But I think that's a rather human value and I don't see why the AI would share it.

Here's the problem. It would be astoundingly unlikely that we would still exist if such a civilization existed.

For this to have happened, it must have happened much less than a million years ago, otherwise your hypothetical civilization would already have easily consumed the entire galaxy.

Since we are still here, if that civilization exists, it must have arrived on the interstellar scene less than one quarter of one tenth of one percent (< 0.025%) of the age of the solar system ago. That seems like a crazy unlikely chance.

This is the fundamental problem with Von Neumann probes / AI grey goo in general : They eat the galaxy way, way faster than anyone can imagine. If they exist, why are we still here?

We commonly consume most available resources and try hard to destroy much competing life... in a given part of what we consider as our territory (our planet), for example when establishing then maintaining/growing a city.

Earth may be part of what an alien species consider as their territory.

No, they're currently terraforming Earth¹ to have a CO2 level that is better for their metabolisms.

¹ through influencing politicians and the rich and powerful to keep poisoning the Earth with extreme pollution.

The politicians and rich and powerful are the aliens.

https://www.google.com/amp/s/www.indiewire.com/2014/10/john-...

I so thought that was going to be a link to The Arrival.

Regarding the prime directive as a mushy human emotional idea. I don't think it's unreasonable for some advanced society to see preservation of newly encountered life as a worthy goal even as a selfish motive. How many new ideas and ways that nature solves problems are we still learning just from the life on earth?

What you are missing is that technological advancement can accelerate exponentially. Couple this fact nothing can move faster than light. This means if you don't stamp out alien life as soon as you encounter it then the next time you come back they might already have achieved technological parity with you. And they might not be as forgiving as you are. This means you have to hide and you have to exterminate any alien life that knowns about your existence. I do think if oumuamua was an alien probe then we should be gravely concerned.

> the next time you come back

This is imagining that space exploration is done by human-like entities that have discrete physical bodies and slow reproduction rates. They come to a place, check it out, and move on.

AI-driven Von Neumann probes would operate very differently. They arrive, and they settle and replicate. Eventually they send out new probes. But they don't leave once they have arrived. There's never any reason to leave.

Okay the point is you won't wait to mobilize against alien life. Assuming that technology increases exponentially it will be prudent to launch as soon as you detect the alien life even if it takes you a hundred years to reach the destination.

What resources does Earth have that wouldn’t be more plentiful elsewhere? Minerals are cheaper to extract from asteroids (no gravity well). If I have the ability to cross interstellar space, then I can’t imagine that water is even worth that much.

Sweet sweet human flesh...

Those are not the only two options.

Besides, we still routinely fail to spot asteroids until they get close to Earth or pass by.

There may be more dwarf planets like Pluto, or a major planet the size of Neptune (per Caltech researchers, so called Planet Nine or Planet X) in our own solar system and we can't easily find them.

No need to intentionally hide from the primitive humans that are still struggling to locate large objects in their solar system and near their planet.

The existence of other planets doesn't seem to explain why they wouldn't colonize Earth. I would expect them to go everywhere.

What would the point of going everywhere be?

To harvest all available resources in the service of whatever higher goal the civilization has.

Maximize resource collection and manufacturing? Surely there's usefulness in raw materials.

Speculating about the motives of a species that may or may not be biologically similar to us and which, even if they are similar, may well be millions of years more advanced than us is very hazardous. I think these kinds of speculations lead many people to hold all sorts of strongly held but unfounded beliefs about what ET's may or may not do here.

Maybe after another million years of development a species' main motivation would be simple curiosity, in other words they are basically scientists. Scientists may want to avoid interfering with a species they are studying and therefore remain hidden. But then the same scientists conducting a different experiment may want to selectively perturb the specimen's environment to probe their psychological reactions and degree of intellectual development.

https://arxiv.org/abs/1302.0606 MAD with Aliens? Interstellar deterrence and its implications

Just from reading the abstract that looks extremely speculative. Frankly you might as well try to make inferences about human behavior by studying aggression in bees.

Exactly, the classic Terran (of the norm), functions mainly with the help of cognitive biases and other syndromes preventing him, by social cohesion, to admit other tunnels of reality than those that composed their groups (majority currently) It's a pity, with a brain so powerful, if you knew what you could understand, admitting to omit the permanent self-awareness.

Exactement, le terrien classique (de la norme), fonctionne principalement à l'aide de biais cognitifs et autres syndromes l'empêchant, par cohésion social, à admettre d'autre tunnel de réalité que ceux qui ont composé leurs groupe (majoritaire actuellement) C'est dommage, avec un cerveau si puissant, si vous saviez ce que l'on peux comprendre, en admettant d’omettre la permanente conscience de soi.

If this is a quote, how can I read the rest?

They?

She

Hmm...She!

Someone asked this once and now I can't stop thinking about it:

There's so much good stuff out in the Oort cloud, why would you ever bother climbing down the gravity well, let alone attacking the poor primitives most of the way down it?

A more likely "War of the worlds" scenario would be someone mining the outer solar system to bits and leaving without us being able to throw so much as a rock at them. If they take enough, even our ability to hunt them down for revenge would be significantly hampered.

Agreed. I don't sneak up on the ant colony that's become too close to my house before I dispatch it.

(We are)

That reminds me of the books We Are Legion, We Are Bob.

I really enjoyed those!

Book 4 is on preorder now, drops in September.

> Realistically, though, it's too much of a coincidence that such a probe would first arrive so soon after we gained the ability to conceive of it.

It is based on TIME but our conception of it would be independent.

I think a lot of what's part of the drake equation is merited on overlap. It's entirely possible that other civilizations have been created and died out LONG before mammals even evolved.

IF you factor in just the last 200 years of human technological advancement it's plausible in another 200 we will have either destroyed ourselves or evolved into gods.

Either way we're not going to be talking to anyone in the universe.

I think it's plausible that a god would not want to talk to another intelligent civilization. Why would we? We would be to a god what bacteria is to us.

I don't really have a conversation with the bacteria infecting a wound. I just take antibiotics.

> I think it's plausible that a god would not want to talk to another intelligent civilization. Why would we? We would be to a god what bacteria is to us.

That may be because we can't even perceive bacteria, but if we go a little bit bigger and you could have a conversation with a dog, cat, deer, or any other animal, I bet you would. I know I personally would just to understand how those animals think and the differences between them and us.

With that said, I do agree with you, but I don't think this is really a comparable analogy though because I'm sure a god wouldn't want to converse with us due to boredom of interacting with plenty of other intelligent life and pretty much everything else before reaching us.

It's hard to conceive of an intelligence as much above ours as we are above bacteria cell. But if such a thing did exist why would it want to communicate with us?

If I could talk to cell(s), morphogenesis would be my topic of discussion.

I don't really understand what this "evolving into godhood" means, but I would really like to talk with the bacteria if I could, even if I might still take antibiotics after talking to it.

> I don't really understand what this "evolving into godhood" means

Not dying of old age or saving your memories/consciousness into a computer and transferring into another body.

> I think it's plausible that a god would not want to talk to another intelligent civilization. Why would we? We would be to a god what bacteria is to us.

At that level of abstraction it might make more sense to think of humanity itself as an organism, and to their point of view an infant one. At the point we either either birth an AI or elevate people to digital organisms with vastly greater intelligence, then we've "matured".

There's still reasons for adults to talk to or help adolescents, mainly to help them mature well, so there might be reasons for "gods" to talk to us.

It might also be that we're only at the stage of speaking gibberish, so there's still a bit to wait.

maybe we are just "ants" for them. That would be the current intelligence level of humanity for aliens.

Doesn't the cities, human civilization on Earth feel like a big messy anthill?

All our society could feel for them just like what we see when we look to what ants have built.

"Nice engineering down there, they communicate using sounds and directed energy, nice they've discovered electricity, they solve their conflict using mostly primitive kinetic weapons. Hey they have developed shows to fill the free time they've got now after having setup some automatization. And now they have a planet reaching data network, how nice.

They're quite aggressive tough, I wouldn't put my finger in there, they bite, hard enough"

I don't expect ants, either as an individual ant or as a colony, to necessarily be able to hold a conversation given enough time, but an alien species more advanced than us, or a godlike AI, may expect at some point in the future we might be able to, or might birth something that is able to (if not, where did they come from?), which is why I think they would be more likely to view us as infants currently incapable of conversing with them usefully rather than bugs with no hope of doing so.

> I don't really have a conversation with the bacteria infecting a wound

Could it be because you know they won't reply? That's the case with most animals. Talking to a random dog or cat (relatively intelligent creatures) and knowing they don't understand a thing you say just kind of makes it pointless. Of course they'll understand simple universal body actions and react, but nothing more.

If there was a bacteria or a cat who would reply back, or at the very least clearly understand what I'm saying, I'd be happy and amazed, and definitely would want to continue talking to them.

What if an AGI’s intelligence has exploded to a point where human intelligence is insignificant?

it's based on what we understand as being intelligence so what would that even mean?

> it's too much of a coincidence that such a probe would first arrive so soon after we gained the ability to conceive of it.

Perhaps they observed I Love Lucy and Gilligan and came by to complain about spectrum pollution.

I don't think so. Light sails are not fast. It would have taken the probe millions of years to get here.

Speaking of pet theories, here is mine: There exists a sentry system of interstellar buoys that get sucked into star systems passing by. Perhaps with a solar sail, so they can control a bit which stars they want to take a closer look at. Our solar system become "recently" a candidate for obvious reasons. The probe made its analysis and plotted a fast escape, sending a tight laser beam to the next closest relay station. A fleet of planet biosphere erasing machine intelligence dispatch is on its way. Probably some ancient left over from AIGs engaged in eternal warfare. Hence a dead silent galaxy, a rather dark forest.

Or, in other words, the main plot line in the Inhibitor trilogy within the Revelation Space series by acclaimed sci-fi author and astrophysicist Alastair Reynolds. https://www.goodreads.com/series/56392-revelation-space

Ha! Thanks for the reading tip. I was unaware.

Mercury provides solar power but you need a lot more energy to get from there to earth. The asteroid belt still provides adequate solar power with I'd guess an easier ability to 'fall on the earth'. It wasn't clear whether the goal of your invader was destruction or takeover. Falling rocks would do the destruction job.

The point is obviously more probes. I think a sufficient gravity field and planetary mass is going to let you work a lot faster. Robotic probes with basically no atmosphere to get through means you can use kinetic cannons to get off-world.

Your initial "factory line" would be a mostly underground equatorial band on Mercury.

Maybe, but the trajectory of the object seems more consistent with having dropped someone off at Mercury, not the asteroid belt.

This is clearly a visitor from Bajor.

https://memory-alpha.fandom.com/wiki/Bajoran_lightship

Excellent page discussing the physics of colonizing mercury: https://einstein-schrodinger.com/mercury_colony.html

"Colonization of Mercury appears to be a very real and practical possibility, whereas colonization of Mars or the other planets, moons or asteroids is really more in the realm of fantasy."

A big advantage of Mercury over mars is higher light intensity: "One very important advantage is the high solar light intensity, which is stronger than on Earth by a factor of 10.6 at perihelion and 4.6 at aphelion"

Cool! Personally, I like the idea of building a Dyson swarm out of it (sorry Mercury!) https://www.youtube.com/watch?v=pP44EPBMb8A

Big disadvantage of Mercury is its depth in Sun's gravitational well. This is worse than planetary escape velocity, because you have to pay it on both ways (to get to Mercury as well as get back). Another problem is radiation which this close to Sun and with no atmosphere is pretty huge issue.

Light intensity is irrelevant. Energy in the form of light is pretty much free within solar system unless it is somehow obstructed. Free in that you don't need to take it with you and it is completely renewable. If you have less light you just gather it from a larger area. Mars has actually pretty good light intensity because it has thin atmosphere (it blocking much less electromagnetic spectrum).

For a colony much more important are parameters: how difficult and long to get there, how much need to be taken with you (ie. do you need to have water/air with you), how much protection you will need to live there (temperature, differences, atmospheric pressure, radiation, gravity, etc.)

Can you explain why you have to pay for the Sun's gravitational well on the way to Mercury? From the famous XKCD illustration[1] I get the impression that it might be hard to "stop at" Mercury since the pull of the Sun is relatively strong. Is there no clever trajectory that comes close enough to Mercury to get caught in its orbit?

[1] https://xkcd.com/681/

You want to stop when you get to Mercury. In the XKCD illustration you have fallen quite a bit from Earth to Mercury and now have that as kinetic energy. You can dissipate that by hitting Mercury but that would likely have significant negative side effects.

Loosing the energy on Mercury is only part of the problem. You also have to get there.

Contrary to popular belief, going closer to the Sun is as much difficult as going further away from it. Orbits require energy to change them regardless which direction you want to do it. You can go to tables and see going to Mercury costs almost the same as going to Jupiter: https://en.wikipedia.org/wiki/Delta-v_budget

There are handy maps of Sol system if you are interested: https://forum.kerbalspaceprogram.com/index.php?/topic/131682...

You can of course minimize the energy even further using gravity assists, but this would require multi-year journey.

There is another trick when you want to go very close to the Sun, which is to go further away first, and then use much less energy to actually stop your orbital speed and fall however deep into Sun well you want. Unfortunately, Mercury is just far enough from the Sun to make it unprofitable and it also takes an awful amount of time to execute.

A better image (imho): https://i.imgur.com/SqdzxzF.png

I think Randall's image is a bit misleading. I mean it is correct and fun, but for an uninitiated person it might cause impression that going down the well costs zero energy.

That of course is true, if you are stationary. Then you just start falling like apple from apple tree. But almost no objects in space are stationary, typically everything orbits something and frequently multiple things at the same time. Think about a rocket that is on an orbit around Earth. It is not free to fall to Earth, it must expend delta V to slow down enough so that its perigee is within Earth atmosphere (and typically well within atmosphere or it will just bounce off it).

At the same time, the rocket orbits the Sun, so even if it leaves Earth it still is not free to "fall" into Mercury. It must expend delta V to slow down so that its perihelion lowers at least to Mercury orbit.

So the graph on xkcd is correct, but with regards to bowling balls you might want to shoot up or let fall down from a position that is stationary in some celestial body's frame of reference.

Kim Stanley Robinson wrote a book, 2312, which featured an equatorial city on Mercury mounted on massive concrete rails.

The expansion of the concrete rails on the day side permanently keeps the city in the planets relatively pleasant pre-dawn zone.

The city only needed to move at walking pace to stay ahead of the sunrise.

IIRC one of the major mercurian industries was maintaining massive solar reflectors that were used to boost light going to specific asteroid greenhouses.

What if the city would have engine trouble, though...

It had no engines. The sun-side tracks thermal expansion provided the energy to keep pushing the city into the night-side.

> it's too much of a coincidence that such a probe would first arrive so soon after we gained the ability to conceive of it

We've gained the ability to conceive of complex stuff only some thousands of years ago. Everything is "too soon" on that scale.

> Realistically, though, it's too much of a coincidence that such a probe would first arrive so soon after we gained the ability to conceive of it.

Are you sure it's a coincidence? Imagine you are an intergalactic species that advances yourself by invading other worlds and stealing the inhabitants' knowledge and technology. What would be the best time to invade? I would suggest waiting as long as possible in their technological advancement but just before they develop the ability to defend themselves.

Light sails are not very fast. The probe would have had to have been launched thousands of years ago at least, maybe millions. Either way, long before our current level of advancement could have been predicted.

I'd argue development isn't linear, as we seem to have millennia with pretty static tech, then in the span of a (increasingly long) lifetime, electricity, flight, and the internet. On that scale, our last 150 years could have occurred randomly at any time.

> as we seem to have millennia with pretty static tech,

That's not even remotely true. Even between antiquity and middle ages there were constant technological improvements. Of course everything sped up once we had access to steam and later fossil fuels as machinery to replace manual work became a reality.

Would a species that has mastered intergalactic travel really have anything to learn from us? I think they would either kill us, eat us, enslave us, or maybe all of the above.

you forgot another real option, "ignore us", just like we ignore ants when we walk around.

Or "blow up our sun before we can get uppity" - 3 Body Problem.

I thought one of the main issues arising with the "alien tech" theory is that this object was moving too slowly to ever make it to our solar system in any timely manner? Thats not to say it couldn't have slowed down prior to us finding it, but if its a detached light sail why wouldn't the alien probe have detached it at higher speeds to have less mass to slow down?

The probe would have needed to use the light sail to slow down as it approached the target star.

Really, the opposite is a better argument: How could the probe have landed safely on Mercury (or wherever) after ejecting from a light sale that still had enough velocity to escape the solar system?

I thought you were going to say that’s the the discarded lightsail from a probe that’s thousands of years old, and all we were never the target of it. It’s just space trash now.

My theory was it's the Super Dimension Fortress Macross and we can expect a Zentraedi invasion Real Soon now.

...and also first arrive so soon (comparatively speaking) after the publication of The Mote in God’s Eye — an excellent novel by Larry Niven whose plot starts with the arrival of a light-sail powered tube.

Sundiver:

Egg sac for a species of star-dwelling creatures. Hopefully they didn't arrive from Betelgeuse...

Shit happens, as in https://en.wikipedia.org/wiki/Code_of_the_Lifemaker

The prologue is sufficient http://www.baen.com/chapters/W200203/0743435265___0.htm , the rest is a matter of taste.

Personally I found it to be hilarious :-)

> Realistically, though, it's too much of a coincidence that such a probe would first arrive so soon after we gained the ability to conceive of it.

Alternately, this implies that we're visited all the time, but usually by robotic probes flying through the solar system for brief visits before being disposed of responsibly and cleanly.

If we put half the energy we use up arguing about Oumuamua into detecting more interstellar objects we would have the data to end this debate.

I'm a fan of the pragmatic mathematical approach. This was the first thing detected. The chances that the first result is also any sort of outlier are very slim. Detect and track some more of these objects. I'd bet good money that Oumuamua's motion is very explainable once we get some better data from other, similar, objects.

> If we put half the energy we use up arguing about Oumuamua into detecting more interstellar objects we would have the data to end this debate

This HN comment was just the motivation I needed to get off my computer and rededicate myself to polishing eighteen 1.32m gold-plated beryllium hexagonal mirror segments.

What is used, and how long does doing that take?

I think it was sarcasm.

Still interesting what would be used to polish a gold plated beryllium mirror. For instance, looks like they clean it by spraying CO2 snow: https://en.wikipedia.org/wiki/Carbon_dioxide_cleaning

Yeah, I took a gamble.

Just looked at the reference you dropped. Thanks, that is an interesting little rabbit hole.

Be very careful grinding, polishing or otherwise ablating any alloy that contains beryllium. Berylliosis (no matter if acute or cronic) is no joke.

Given a budget of, say, $9.66 Billion, I'd say it would take around 25 years.

https://en.wikipedia.org/wiki/James_Webb_Space_Telescope

You don't need the telescope. There is an effort to discover interstellar objects in old data, which is largely a matter of spotting faint objects and calculating thier orbits...ie coding.

Can you link us to where we can contribute?

https://panstarrs.stsci.edu/

The data is there. Have at it.

Perfect task for AI.

Given this comment, I'm not sure you know what "AI" or "perfect" mean.

You know what, maybe if we put this data on the blockchain, the ICO can pay for future investment to democratize astronomical research ok, I can't keep typing this out, I can't tell if I'm making myself laugh or cry.

Why would this not be a good domain for image recognition?

If you’re trying to classify images as whether or not they contain something, you need a bunch of images that you already know don’t contain the thing (got it), and a bunch of images that you already know /do/ contain the thing. We lack the latter, so there’s nothing for the algorithm to learn based on.

Oh I see I assumed the GP was talking about after such a dataset I agree you likely couldn't bootstrap without a lot of data but couldn't you use more classic approaches to extract data and then train a model (obviously once you know the extraction process is fool proof?)

But this is not the only way you can deploy machine learning techniques. You could deploy unsupervised learning to first learn what visual features are common in such images, and then successively refine until you end up with a set of images containing very rare phenomena. That could give human evaluators then a considerable head start.

In fact, this idea seems so obvious that it must have been tried already…

Has it? I'm very interested in using data science for astronomy as it was my childhood passion and I'd love to read anything you can provide.

I'm sorry, this was pure speculation on my part, I don't have actual knowledge of this happening.

Thank you for sharing that. Are you sure you know what "not sure" means?

Another place: you could get in touch with the folks at ALeRCE (http://alerce.science/). They publish access to a live stream of data from the ZTF project. We found the closest asteroid ever 4 days ago from the ZTF data stream: https://www.caltech.edu/about/news/ztf-finds-closest-known-a...

I know you are joking, but a second interstellar object after the Oumuamua was discovered using a 0.65m DIY telescope built by Gennadiy Borisov.

https://en.m.wikipedia.org/wiki/2I/Borisov

https://en.wikipedia.org/wiki/2I/Borisov

Just like we're the only form of life that we've observed in the universe. The chances that the first result is also any sort of outlier are very slim. That's why with the decades of effort and sophisticated tools that we've employed, we've been able to find and study lifeforms on so many other planets.

Uh, the highest-funded terrestrial telescope project of the last 10 years has been the Rubin Observatory, which is intended to detect more interstellar objects (along with two other large goals - variability studies and galactic rotation curve studies to understand dark energy).

The effort spent arguing about Oumuamua is a tiny, microscopic fraction of grant money in astronomy.

(I work on software to detect interstellar objects)

If we put half the energy we use detecting more interstellar objects to building interstellar spacecraft we'd be able to fly to one to find out what it is.

If we put half the energy we use building interstellar spacecraft on neural implants we'd not worry about flying somewhere else to satiate our desires.

If we put half the energy we use working on neural implants on creating affordable housing and food production we wouldn't have people chasing after dreams of perceptual bliss.

If we put half the energy we put into affordable housing and food production into figuring out what Oumuamua was, we'd discover aliens and they'd solve all our problems.

I don't think a few hundred million dollars a year is going to solve food production or affordable housing.

We can just build a ship to chase down Oumuamua and end this debate. If it is no longer where a natural object with a passive trajectory should be well we have our answer. If it is there we can take a close look.

THe fact that another interstellar object was discovered so quickly made me lose hope in the artifact or ship idea though. Part of the appeal was the idea that interstellar meteors were not really a thing, but apparently they are.

> Asked if there is a clear leading candidate explanation for 'Oumuamua's acceleration, Loeb referred Live Science to a not-yet-released book he authored called "Extraterrestrial: The First Sign of Intelligent Life Beyond Earth," due for publication in January.

I don't know enough about the science to have an informed opinion, but it seems to me that if the main skeptic is also selling a book based in their exciting alternate theory, that's kinda a huge red flag.

First sign? The first was probably the irrigation canals spotted on mars. Then repeating radio signals. The face on mars. Tabby's star. Each had their day as the first sign. The first real detection won't be some slight variance that we debate for years but solid evidence. If Oumuamua was a triangle, that would be solid evidence. It isn't aliens until it is.

Well, even a 'giant triangle' may still not be enough... There is a giant hexagon on Saturn, after all. https://en.wikipedia.org/wiki/Saturn%27s_hexagon

Down in the explanations, a triangle:

> Similar regular shapes were created in the laboratory when a circular tank of liquid was rotated at different speeds at its centre and periphery. The most common shape was six sided, but shapes with three to eight sides were also produced.

Natural processes can make lots of structures that look artificial. See Giant's Causeway: https://en.wikipedia.org/wiki/Giant%27s_Causeway

"Worth seeing but not worth going to see" –Charles Dickens

And pyrite (fool's gold) crystals: https://en.wikipedia.org/wiki/Pyrite

"It [the giant hexagon] rotates with a period of 10h 39m 24s, the same period as Saturn's radio emissions from its interior."

Interesting. Thanks for posting.

Evidence can be solid as can be, but it will still be debated, made political, etc.

> The first real detection won't be some slight variance that we debate for years but solid evidence.

Don't count on this. It could well be some ambiguous anomaly in the atmospheric spectrum of an exoplanet that we only decide is real after years of alternate hypotheses.

The face with a mountain with coincidental lighting. Everything else has very plausible natural explanations as well.

You're hearing footsteps and hoping for zebras when it's probably horses.

Human neurology is optimized to see and recognize faces, so of course anything facelike will look like a face. Faces in clouds, faces in the uneven paint on drywall, the Man In The Moon.

I'm beginning to suspect human culture is optimised to see aliens, so anything potentially alien-like will be labelled "aliens."

Real aliens stand a good chance of being unimaginably, perhaps even invisibly, alien.

What are the odds that in a galaxy that is billions of years old, first contact will be an encounter with a contemporary-ish technology straight out of a 20th century science fiction novel?

With this approach, you’d be skeptical too if Charles Darwin was also selling a book with his exciting alternate theory on the origin of species.

Yes, if Charles Darwin would publish a book today, with a focus on a layman reader, and then give interviews, instead of publishing his findings in journals, I would be skeptical.

But he is publishing in journals. The article cites his papers.

It’s a very “academic” thing to do. Cite yourself as often as you can.

I follow the What da Math[0] channel on YouTube to keep up with the latest news on cosmology. I highly recommend it. Very thorough and with daily updates.

[0] https://youtube.com/user/whatdamath

The subhead is "Aliens? Or a chunk of solid hydrogen? Which idea makes less sense?"

The better version would be: "Journalism? Or Clickbait? Which idea makes less sense?"

"Scientific American" indeed.

I think it's extremely low density collection of dust particles held together by electrostatic forces. AKA a cosmic dust bunny.

Maybe interesting idea for long distance engine, worth exploring.

Oh this is an article without substance just to promote a book?

Read the last sentence of the article. Bias warps perception. This shouldn't even be posted here.

>Asked if there is a clear leading candidate explanation for 'Oumuamua's acceleration, Loeb referred Live Science to a not-yet-released book he authored called "Extraterrestrial: The First Sign of Intelligent Life Beyond Earth," due for publication in January.

I don't understand - is it unexpected that the person forming an argument for the alien hypothesis has written a book about it? That's not usually what people mean when they say "bias", and it's even further from being a good reason that the entire article "shouldn't be posted here". Or are you just making the assumption that the book's dumb "clickbaity" title must mean the author is full of shit?

It seems obvious to me that if one intends to make money from a theory it is in their best interest to champion said theory even in the face of conflicting research and alternate explanations.

At least until the book is out

The profession of research scientist is the profession of making money from theories.

> This shouldn't even be posted here.

From the HN Guidelines:

"anything that gratifies one's intellectual curiosity."

https://news.ycombinator.com/newsguidelines.html

Also don't judge a book by its title. Until you've read the book then you can't comment on whether there's a bias in play.

The same guy has published the idea of the solar sail in a paper (or preprint?). Solar sails are his research topic.

The calculations that a solar sail can survive an interstellar travel are probably ok.

The evidence that the solar sail is the most likely explanation is very weak.

Oh sure, and I agree maybe and many theories are likely wrong, but the point of my response was that the post is perfectly valid here on HN because it introduces discussion points such as yours...i.e. it's gratifying our intellectual curiosity (and arguments for and against) despite Loeb's interests...i.e. (sorry) solar sailed interstellar spacecraft. And this is why we're here.

We probably agree.

My guess is that he really knows how much radiation is received by a big block of Hydrogen ice in the middle of space, but I always feel that his opinion about other explanations are biased. I think it's a good submission, but I'd be cautious.

Summary: hydrogen iceberg theory questioned as the expected lifespan of a hydrogen iceberg is likely too short, given the distance Oumuamua would have had to travel.

You forgot about the aliens.

You have failed to account for the fact that we live in a simulation.

Or, we're just a projection in a dream of the all-pervading cosmic consciousness.

It's either aliens, or our estimations of hydrogen iceberg ages is a little off.

Anytime you see an astronomy article in the popular press that sounds a bit flaky, you can bet Avi Loeb's name will appear in it.

Is he the new Carl Sagan?

We all need some more excitement in life, this unexpected piece of rock provides exactly that

Previous discussion:

https://news.ycombinator.com/item?id=24204323

OK, suppose as proposed that the H2 in an object couldn't survive the journey. What makes us certain that Oumu is interstellar? Haven't seen that convincing argument (in human-readable form).

Voyagers I and II are leaving the solar system; they got the kinetic energy to do that. I'm not convinced that all plausible histories for that happening within the SS without human assistance have been explored. As for the makeup of the object ... that will remain hypothetical. Maybe if we'd seen it sooner ...

Are you suggesting that Oumu was some sort of Oort cloud object that was disturbed into a hyperbolic trajectory? That seems a lot less likely than Oumu originating outside of the sun's gravitational influence.

Can't we build a probe that can reach it? What's the fastest we can launch a ton of equipment in Oumuamua's direction?

No, it's long gone.

It's currently traveling at about half the speed of New Horizons, but on a highly inclined plane. The delta-v from Earth seems to be around 60 km/s.

A nuclear powered probe could catch it assuming of course that it continues on a passive trajectory and doesn't change course. Obviously the longer we wait the harder it will get though.

I'm currently watching the Alien movies. Maybe it's better that we are "alone" haha

Alien 3 is an underrated, much maligned, masterpiece.

This is pretty cool. I am constantly looking at current events and thinking to myself "what if aliens were watching this?". I feel like it sorta puts things in perspective for me. Seeing that this might be a possibility is sorta thrilling.

If you think this is cool, you should definitely buy the book this advert is about.

Further we look into the void, further we see how vast it is in length of time and breadth of space. And in that void we're a tiny speck of dust on an already tiny speck of dust. For me, looking at zoomable deep space telescope imagery, it's a 50/50 proposition, either we have the only miracle of life in existence, or it's prolific.

Deepest visible light image of 10,000 galaxies - https://www.spacetelescope.org/images/heic0406a/zoomable/

NGC 1866 star cluster - https://www.spacetelescope.org/images/potw1847a/zoomable/

Runaway galaxy UGC 10214 with thousands of galaxies in backdrop - https://www.spacetelescope.org/images/heic0206a/zoomable/

Abell 2218, a rich glaxy cluster composed of thousands of galaxies - https://www.spacetelescope.org/images/heic0814a/zoomable/

Gordo ("The Fat One") - enormous galaxy cluster with mass of three million billion Suns - https://www.spacetelescope.org/images/potw1802a/zoomable/

Gallery of more of these at https://www.spacetelescope.org/images/archive/zoomable/ - follow a delightful thumbnail, then desperately seek the tiny buried zoomable links on subsequent pages.

The incomprehensible vastness in terms both time and space, combined with our own flittering existence, mean that even a universe utterly teeming with life would never see two advanced civilizations actually cross paths.

Could you elaborate? To me that seems tobe too anthropocentric thinking.

All thinking about aliens is anthropocentric. We have a sample size of one.

Von Neumann self replicating probes would make contact between two very distant civilisations eventually happen. Though that may occur after both civilisations are gone and all that remains are the programmed probes creating relay stations to send out more of themselves.

>it's a 50/50 proposition, either we have the only miracle of life in existence, or it's prolific.

This seems like a false dichotomy. There could be 200 billion planets with life in the universe...but only about one per galaxy. Someone did a probabilistic analysis of the Drake equation, and found out that indeed, given the known facts (that we don't see any life yet, how life appears to have developed on earth) that a substantial likelihood exists that the density of life is right in the range where there are many instances but we will never see one. It's sad to never get closure, but it's irrational to deny it's a possibility.

"what if aliens were watching this?"

There is an archetype of the Mysterious Stranger, an innocent, naive observer of our culture, who finds us incomprehensible because we are Just Terrible. We make war, pollute, enslave, etc, while this archetype is pure.

Examples: K-Pax, Powder, Dostoyevski's The Idiot, Crocodile Dundee all have elements of this archetype

The thing is, the only reason this archetype has any meaning to us is because this archetype shares our values. That character is always just the author, putting words in the mouth of a character who could not exist in reality. There is no Mysterious Stranger.

We can expect actual aliens, ones who evolved in a different ecosystem, would have no opinion about what we do. Not from our value system anyway. Less "these poor hooman creatures actually kill each other, how primitive!" and more ... well, something more incomprehensible to us

Your moral objectivity is concerning.

Did you mean relativity? It seems to me that the comment does imply moral relativity is true.

We can no more expect aliens to hold our moral values than we would expect bats or bees to do

> We can expect actual aliens, ones who evolved in a different ecosystem, would have no opinion about what we do. Not from our value system anyway. Less "these poor hooman creatures actually kill each other, how primitive!" and more ... well, something more incomprehensible to us

TVTropes has a whole section called "Blue-and-Orange Morality" for this: https://tvtropes.org/pmwiki/pmwiki.php/Main/BlueAndOrangeMor...

I don't think that's true. I could conceive of an alien "prime directive" like in Star Trek. So saying that it's out of the question is definitely not something that I believe. Humans, after all, are constantly observing other species. Why wouldn't aliens?

Can you expand? I don't see the logical connection between "I can conceive it" and therefore it's possible.

I mean, it's possible aliens are so similar to us we could communicate and share values. I just don't see why we would expect it, given that they will have evolved in a completely different environment with completely different evolutionary pressures. We would be far more likely to figure out what whale songs mean than communicate meaningfully with aliens

I'll leave aside my personal favorite pet answer to the Fermi Paradox that we have not evolved the ability to even perceive aliens; but suffice to say when I mean aliens are different, I mean different, not just basically people with funny ears

So, to my mind, the question to answer is not "Why wouldn't aliens?" but "Why would they? How would it even be reasonably possible?"

There may be some universal aspects to sentience. Especially one that, presumably, comes knocking at our door. Any energy and/or resource consumption probably leads to expansionary tendencies to acquire more resources and energy. And if they come here, that implies they have some technology or ability for motion, which I’m fairly certain necessitates energy usage. So, on some real base level, they’d probably want ‘stuff.’ And when you think about it, wanting stuff drives a lot of our evolved biology and social structures. I’d venture to guess that if aliens ever do show up, there would be at least some mutually recognizable aspects.

Now my favored theory is that there are no other sentient species within a detectable range from us, and same goes for any of them out there too. Time to start accepting that we’re (functionally) all alone out here.

"There may be some universal aspects to sentience."

I'll define sentience for us quite loosely and vaguely to mean "has self awareness" and "knows stuff that would be useful to us", like new fields in mathematics and physics. LMK if that's incorrect.

There may be universal aspects to that, and we're only speculating, so you could be right ¯\_(ツ)_/¯ I have a feeling that "sentience" as a general concept, whatever the definition, contains these "universal aspects" right in the definition, begging the question.

We only have a single data point for even recognizing what sentience is: as you say, some indicators are "motion", "wanting stuff", "energy usage"

Since there are example on Earth of creatures that have all of those traits that are definitely not sentient, can I assume you mean at greater scale? So, motion across interstellar distances and what that implies.

To my mind, motion across interstellar distances is neither necessary nor sufficient to demonstrate "sentience" as defined above. I can easily imagine a mindless entity evolved to spew spores into space with only enough sentience to take advantage of gravity sling shots to speed themselves along the way, that we mistake for spaceships. Or highly advanced, sentient creatures that are immobile, that look to us like barnacles or slime mold, that take thousands of years to complete a single thought.

At the end of the day, I believe we are going to recognize only creatures that evolved under very similar circumstances to us as "sentient": can manipulate objects; can emit signals we recognize as such, at a scale we can comprehend; bonus points for spaceships, clothing, machinery; bonus points for using scientific principles that we do not yet know, but would find useful.

I suspect (admittedly without due cause) that this kind of sentience is exceedingly rare relative to the potential diversity of what is possible; which is to say, that post-first-contact humanity will find our definition of sentience to be astonishingly narrow

Certainly I only watch with fascination when ant colonies destroy each other, I expect we appear much the same as ants to higher life forms.

> There is no Mysterious Stranger.

... besides ourselves. It's not that we don't relate to anyone or anything this way; its that the relation is reflexive.

Yes! Exactly.

Why does it have to be a hydrogen snowball? Because no tail was detected that would have indicated a dirty methane-etc snowball? What about an stony asteroid-like object?

Quoting the article:

"While a few other substances (like solid neon) could potentially explain the coma-free acceleration, hydrogen was the best match for the data."

It doesn't have to be hydrogen. But to explain acceleration from solar heating it does need outgassing, and the outgassing has to be in a form that we can't detect (no comet tail). Stone won't have much (or any) of that.

Well, if it was hydrogen iceberg it would not only accelerate when leaving Sol system, it would also decelerate when closing in.

Right, but we didn't notice it till to late.

To start playing aliens throw us a snowball. What would have happend when Oumuamua would hit our planet?

If it was composed of solid hydrogen then very little. It would evaporate at slightest touch of a planets atmosphere. Maybe even bounce off it.

For solid hydrogen any planet with atmosphere is like a ball of hot molten lava for a snowball.

Edit: I was half expecting there to be a video of throwing snowballs into lava, Internet does not have it all, yet.

Sounds like something to add to the bucket list.

I have a strong belief that we will establish first contact by 2040.

Based on what?

Belief, a feeling. Nothing tangible. Almost 6th sense like.

It could be a probe that scans solar systems. I like that idea.

Personally I find it suspicious for the first alien object detected to be of a shape of standard human poo.

2020. 'nuff said.

I feel we’ll be visiting it in a couple hundred years.

2020 isn't quite over yet

I suppose they need to drive traffic on “scientific”american by either flouting aliens, mysteries, or objects the size of several thousands football fields or washing machines.

There is nothing alien about this space object other than its geological origin.

I don't get it. Why don't we image this thing directly?

It gone.

We have! https://en.m.wikipedia.org/wiki/ʻOumuamua

But it’s small and moving away from us fast. We couldn’t build anything in time that could catch up to it and image it closer.

Politically no. When we first saw it, technically maybe yes. In an all stops pulled scenario, an improvised rocket could have been sent and at last had a fly-by look.

Now... doubtful it could be done at all.

> We couldn’t build anything

We could, but we didn’t.

https://arxiv.org/abs/1711.03155

Interesting.

The trajectory of O'uamuamua seems almost.. designed to scout the Sun's habitable zone.

https://upload.wikimedia.org/wikipedia/commons/thumb/f/f5/Ou...

I think the theory is that it wasn't really moving relative to the sun and kinda just fell in.

https://en.wikipedia.org/wiki/ʻOumuamua

A nuclear pulse vehicle could catch it easily even if we waited 50 years to launch. Its slow speed is actually the best argument against it really being an active spacecraft because even we could do better. Much better. It could be part of a swarm of millions of low tech ships assembled from local resources though.

Uh, because of the most obvious reason that comes to mind: it's way too small and way too far away! Even when it was discovered, near the perihelion of its hyberbolic orbit, it was small enough that we had no way whatsoever actually resolving it as anything else than a point of light. We could only guesstimate its rough shape by measuring its light curve—how its brightness changes as it rotates—and then simulating what kind of shape would produce that light curve. And now it's already way beyond Saturn's orbit, almost 100 times farther away than when it was discovered.

Could the JWST see it? It goes up soon.

For a broad value of soon.

Will that be the most valuable asset put in space on one lunch? Aside from stuff we don’t know about of course?

Obligatory joke about putting IP lawyers in high orbit first.

And on far-off Earth, Dr. Carlisle Perera had as yet told no one how he had wakened from a restless sleep with the message from his subconscious still echoing in his brain: The Ramans do everything in threes.

We just have to hope there is at least one more

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