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Could 'Oumuamua Be A Fluffy Radiation-Driven Icy Fractal From Another Star System? (syfy.com)
"Oumuamua, the first object ever seen passing through our solar system from interstellar space, was thought to be emitting gas like a comet to explain its weird motion," reports Syfy Wire, "but a new idea is that the comet is just very, very porous."
Astronomer Phil Plait writes: It was hard to tell what it was; it was too small, faint, and far away to get good observations, and worse, it was only seen on its way out, so it was farther from us literally every day. Then another very weird thing happened: More observations allowed a better determination of its trajectory, and it was found that it wasn't slowing down fast enough. As it moves away, the Sun's gravity pulls on it, slowing it down...but it wasn't slowing down enough. Some force was acting on it, accelerating it very slightly... A new paper has come out that might have a solution, and it's really clever. Maybe 'Oumuamua's not flat. Maybe it's fluffy... [And thus moved by the force of sunlight giving it a tiny push]
When stars are very young, they have a huge disk of material swirling around them; it's from this material that planets form. Out far from the star, where temperatures in the disk are cold, teeny tiny grains of dust and water ice can stick together in funny shapes, creating fractals... Materials made in a fractal pattern can be very porous, and in fact out in that protoplanetary disk around a young star, physical models show that objects can grow fractally until they're as big as 'Oumuamua, and have those extremely low densities needed to account for its weird behavior. So 'Oumuamua doesn't have to be a spaceship. It just has to be a snowflake! A three-dimensionally constructed phenomenally porous low-density snowflake... [T]he new paper suggests it came from a nearby star, and one that's relatively young (less than 100 million years). It formed out in the disk, and got ejected somehow, likely from a planet forming nearby giving it a boost from its gravity.
"I certainly hope we find more beasties like this one," Plait writes. "They can tell us so much about how planets form in other star systems, which is pretty hard to figure out from dozens or hundreds of light years away.
"It's a lot easier when they obligingly send bits of their building materials to us."
Astronomer Phil Plait writes: It was hard to tell what it was; it was too small, faint, and far away to get good observations, and worse, it was only seen on its way out, so it was farther from us literally every day. Then another very weird thing happened: More observations allowed a better determination of its trajectory, and it was found that it wasn't slowing down fast enough. As it moves away, the Sun's gravity pulls on it, slowing it down...but it wasn't slowing down enough. Some force was acting on it, accelerating it very slightly... A new paper has come out that might have a solution, and it's really clever. Maybe 'Oumuamua's not flat. Maybe it's fluffy... [And thus moved by the force of sunlight giving it a tiny push]
When stars are very young, they have a huge disk of material swirling around them; it's from this material that planets form. Out far from the star, where temperatures in the disk are cold, teeny tiny grains of dust and water ice can stick together in funny shapes, creating fractals... Materials made in a fractal pattern can be very porous, and in fact out in that protoplanetary disk around a young star, physical models show that objects can grow fractally until they're as big as 'Oumuamua, and have those extremely low densities needed to account for its weird behavior. So 'Oumuamua doesn't have to be a spaceship. It just has to be a snowflake! A three-dimensionally constructed phenomenally porous low-density snowflake... [T]he new paper suggests it came from a nearby star, and one that's relatively young (less than 100 million years). It formed out in the disk, and got ejected somehow, likely from a planet forming nearby giving it a boost from its gravity.
"I certainly hope we find more beasties like this one," Plait writes. "They can tell us so much about how planets form in other star systems, which is pretty hard to figure out from dozens or hundreds of light years away.
"It's a lot easier when they obligingly send bits of their building materials to us."
I like this kind of articles, they expand my knowledge of things astronomical.
...gis sdrawkcab (usually not responding to ACs; don't bother posting as AC)
"Oumuamua doesn't have to be a spaceship"
Um, if there is one thing it is not is a spaceship. Can we get any dumber? Where would a spaceship possibly come from? There is no system close enough to Earth. It would take hundreds of thousands of years for a spaceship to get here from anywhere.
Something approximating a Sierpinski Pyramid (which has zero density)?
for billions of years, some star probably exploded and destroyed the planets orbiting it sending debris hurtling though space possibly beyond the galaxy that it resided in, but more than likely it resided in this galaxy
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See, this is why publishing even highly speculative papers can be productive. I see this as a response to the paper that everyone keeps talking about in terms of 'omg aliens!', where really the person just layed out how much the object would have to weigh in order for its movement to be described like a light sail and then speculated about what types of objects, such as artificial ones, could have that kind of weight to volume ratio.
So now here we have another person taking that idea and proposing how something with those same characteristics could have a naturally occuring origin. This is what I love about watching scientists figure something out. You start with a mystery, someone proposes a mathematically consistent but kinda out there solution, others pick it apart, work with some bits while dropping others and propose a new solution. This is one of the major reasons publication is so important, so others can build off of ideas, even half baked ones.
As the fluffy icy fractal hypothesis is completely naturalistic, it is simpler.
You're thinking of Ultima Thule.
Think of the profits to be had from lassoing that "rock" and bringing it back to earth! We could close down the melamine mines forever! No one will ever have a yucky bathtub again!
If we could only figure out what the Dark Knight Satellite is. /sarc
Oumuy McOumuyface would have been more appropriate.
...wouldn't we have seen some out gassing if this thing were made of water when we first detected this? And isn't that precisely one of the mysteries with this thing, is that we didn't see any out gassing?
Mod me down with all of your hatred and your journey towards the dark side will be complete!
No I wouldn't be happy with it being a spaceship because it would violate several laws of physics.
Oumauamua could be an outgassing comet-like body. Or, if it is a solar sail, and outgassing, in which case any acceleration we see must be explained by photonics pressure alone. This calculation give the very low densities given in the post.
In one astronomy post web group (which is hardly a scientific survey) the original argument that Oumauamua was a solar sail were accepted as "promoting the discussion", but there were demands that early papers for the scientific community replying on arXiv were not properly peer reviewed and so should be stricken from the record. This is weird: not only were the authors and arCiv doing a reasonable job against a set of unsubstantiated claims, you would also not expect a peer-reviewed article to come as quickly. So, in effect we are allowing people to post wacky propositions about alien spacecraft, but not allowing rational criticism from the body of experts whoo is most likely to have a useful contribution.
Astronomy is a long game. Have your little victories winning short-term arguments this way. The stars will be much where they were when you have long gone. And whoever was right will still be right. We can all wait.
That's an untestable hypothesis. Until we resort to it, lets put up all the testable ones we can think of! The "fluffy crystal" thesis is testable: Can we create similar fluffy structures in zero gravity?
What are you talking about? What laws of physics say an object, artificial or otherwise, can't travel from one solar system to another? Heck, whatever Oumuamua is, it's an existence proof to the contrary.
Should I clarify that when we talk about the spaceship hypothesis, we're not saying we think it's an *operational* spaceship full of living aliens? A multimillion-year-old, and (duh) long-dead, spaceprobe would fit the bill too.
Is there some law of physics I'm not aware of that says it's impossible that, millions of years from now, our Pioneer 11 (for example) might drift close enough to some other star to make a similar hyperbolic swing around it and cause the aliens living there to have this same argument?
(Of course I'm not saying it's likely, or that there's any scientific evidence for it, but why should it be *impossible*?)
David Gould
main(i){putchar(340056100>>(i-1)*5&31|!!(i<6)<< 6)&&main(++i);}
The problem with the spaceship thesis is that it runs afoul the falsification principle of Science: "We don't know what it is, so lets blame the Little Green Men."
Little green men are falsifiable too. Aliens are quite likely to actually exist. Quite a few scientists believe that we are probably not the only intelligent species in the Milky Way. The idea that Oumuamua might be an artifact of some kind is very falsifiable. We could chase the thing down and take a look. We could send back photos of its surface from 10 feet away. It is only attitudes like yours that make us unlikely to ever try.
Quite an experience to live in fear, isn't it? That's what it is to be a slave.
Put a fork in it because this web site is so done. Look at the responses to this interesting 'special snowflake' hypothesis to explain the only interstellar object we've ever seen. Sigh. This used to be a place where at least some highly intelligent people would post. Not anymore.
Quite an experience to live in fear, isn't it? That's what it is to be a slave.