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Mystery of interstellar visitor 'Oumuamua gets trickier

scientificamerican.com

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Re: Mystery of interstellar visitor 'Oumuamua gets trickier

#181

Post by 8bitsrule »

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 ...

Re: Mystery of interstellar visitor 'Oumuamua gets trickier

#182

Post by kentonv »

pavlov wrote: post #158
kentonv wrote: post #128

Earlier quoted context omitted.

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 th…

“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.

Re: Mystery of interstellar visitor 'Oumuamua gets trickier

#183

Post by dodobirdlord »

8bitsrule wrote: post #181

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 make…

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.

Re: Mystery of interstellar visitor 'Oumuamua gets trickier

#184

Post by kentonv »

landryraccoon wrote: post #145
throwaway316943 wrote: post #116

Earlier quoted context omitted.

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? I…

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.

Re: Mystery of interstellar visitor 'Oumuamua gets trickier

#185

Post by bitwize »

kentonv wrote: post #47

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 direc…

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

Re: Mystery of interstellar visitor 'Oumuamua gets trickier

#187

Post by lmilcin »

monkeypizza wrote: post #123
kentonv wrote: post #47

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 direc…

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…

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.)

Re: Mystery of interstellar visitor 'Oumuamua gets trickier

#188

Post by knome »

landryraccoon wrote: post #150
kentonv wrote: post #128

Earlier quoted context omitted.

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 th…

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 nuts…

>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"?

Re: Mystery of interstellar visitor 'Oumuamua gets trickier

#189

Post by codeflo »

lmilcin wrote: post #187
monkeypizza wrote: post #123

Earlier quoted context omitted.

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…

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 obstr…

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/

Re: Mystery of interstellar visitor 'Oumuamua gets trickier

#190

Post by selimthegrim »

wffurr wrote: post #164
KozmoNau7 wrote: post #124

Earlier quoted context omitted.

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.
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