Was Oumuamua an Alien Solar Sail? | Hacker News Reader

Was Oumuamua an Alien Solar Sail?

phys.org

24 pointswallace_f19 comments

> As for what an extra-terrestrial light sail would be doing in our solar system, Bialy and Loeb offer some possible explanations for that. First, they suggest that the probe may actually be a defunct sail floating under the influence of gravity and stellar radiation, similar to debris from ship wrecks floating in the ocean. This would help explain why Breakthrough Listen found no evidence of radio transmissions.

Wouldn't it be advantageous for Oumuamua's creators to simply collect data, leave the observed systems alone and start transmitting when those clueless Earthlings aren't listening anymore? This thing was noticed only at 0.25 AU _post_ flyby. It is sort of terrifying that someone might have sent this...

Anyways, I am highly skeptical. For all we know, this was a slightly out-of-the-ordinary rock that swung by Sol. Our current inability to explain its behaviour due to lack of data immediately has people screaming "Aliens!". Well, one notable issue here is that the "Aliens!"-conclusion is not due to evidence for the fact (detected transmissions, clear artificial behaviour or surface structures) but lack of evidence against it. One natural cause for the acceleration when moving away from the Sun as well as the fast spin would be outgassing, but:

> In addition, they cite other research that showed that if outgassing were responsible for the acceleration, it would have also caused a rapid evolution in 'Oumuamua's spin (which was not observed).

Are we sure we didn't just fail to detect it? As nature would have it, improbable configurations might have been at work here and multiple streams of outgassing may have stabilised spin?

>Are we sure we didn't just fail to detect it?

I would be interested in knowing more about the possibility of that from people who study comets.

The alternative theory is the object is an extremely thin sheet (0.3mm thick), which is what these scientists suggest as the best fit for the data. That would be a really thin slice of space rock.

How about from the people who study chance ?

The issue with rare events is that you can never estimate the probability curves. This has the strange result that each one looks unique, complex and very much non-random ... despite potentially being very common, simple and random.

We have one example from an unknown distribution. You can always read a lot into it's exact properties ... but there's nothing to be read, because we don't have the variation on those properties. So this could have been a very common run-of-the-mill interstellar asteroid ... and it could have been an alien explorer. We don't know, and we probably won't know. Well, I guess in the second case we'll eventually realize.

Good ideas. But what I meant was about the possibilities of outgas-propellent existing without them being observable.

As I understand it, Oumuamua spectra is very similar to that of a D-type asteroid. It appears to be covered by a dull red organic gunk (tholins), which would make a very inefficient solar sail.

Is it easier to colonize asteroid belt since water and minerals are easily available?

Gravity still is a problem, but all the resources needed to build colony and sustain life are easily available on lot these asteroids. Also water is great for shielding solar radiation which means on some of these asteroids underground colonizes can pose a lower hazard compared to solar radiation on planets like Mars or our moon.

Not sure re: "easier" but the sci-fi book series (TV now also) "The Expanse" talks a lot about the human colonization of "the belt" and even the morphological "low G" changes humans would have over time. Pretty interesting even for fiction.

Is gravity actually a problem if the colony is underground and the asteroid is spinning?

Spinning would only result in a ring inside the asteroid having the desired gravity. Still might be pretty good though. Not sure what the cost would be to create the desired spin for a reasonably sized candidate asteroid.

I wonder why this post got deranked so fast? Was it user flags or mod decision?

Previous HN discussion: https://news.ycombinator.com/item?id=18338927

Thank you

Would it make sense for an advanced civilization to hollow out asteroids to create interstellar ships?

Probably not, since The quality of the material likely isn't very high and you'd end up with pretty sick walls which result in lots of mass to accelerate. Maybe that's not true for all asteroids and it might differ between solar systems.

parent probably meant *thick walls, but I bet modern lingo like "sick walls" would also apply, as it's a very "rad" idea.

Part of me wishes it was true. But part of me also knows that betteridge's law of headlines is as reliable as newton's laws of motion for everyday life.

> Part of me wishes it was true.

Me too, on one level, but we should be careful what we wish for. If it was an alien solar sail, there's not much in earthly history of two cultures at different levels of advancement meeting that lends much hope for a long-term happy outcome of an intergalactic encounter.

True.

Then at least we had in both cases humans for whom there is God that they will ultimately share similar cultures ("do not kill when not needed", "may share similar feelings",...)

With aliens this is a whole different perspective. I am personally not excited to find out how our worlds may or may not be compatible.

This may be the instance where it has been the most difficult for me to separate what we know from what I hope. The idea that it fit so much of the criteria for Rama probably locked many of us in to wanting to bend the narrative.

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