
‘Oumuamua: A Hydrogen Iceberg? - elorant
https://www.centauri-dreams.org/2020/08/18/oumuamua-a-hydrogen-iceberg/
======
withinboredom
In a short story I'm writing, things like this are sent every few hundred
years to stars with life. Your species is invited to the galactic community
once you can spot it, catch it, and utilize the tech without killing yourself.

~~~
Erik816
You may want to read Rendezvous with Rama by Arthur C. Clarke. That's
basically the plot.

~~~
walrus01
As I recall the first two books are pretty good, after that the novel series
kind of goes off the rails.

~~~
interfixus
As _I_ recall, the original novel is vintage Clarke of the better kind, and
then the rest are [co-]authored by some entity named Gentry Lee and basically
unreadable.

~~~
walrus01
You are right... In this case I think it might be a good example of how
serious scientists are not always the best fiction writers.

[https://en.wikipedia.org/wiki/Gentry_Lee](https://en.wikipedia.org/wiki/Gentry_Lee)

~~~
interfixus
Shame on me. I never knew, and I never bothered to look it up.

~~~
walrus01
It is not an unreasonable assumption to make, there are a lot of novel series
where the 3rd, 4th, 5th novels are ghostwritten by some third party hired by a
publishing company that owns the rights, to cash in on a well known novel's
name and author.

------
mellosouls
Worth noting co-author Avi Loeb produced the headline-making Alien-origin
hypothesis paper of a couple of years ago.

i.e. context: the paper summarised in the OP is his counter to a "hydrogen
iceberg" challenge/alternative to his original "alien" paper.

[https://www.wikipedia.org/wiki/Avi_Loeb#%CA%BBOumuamua](https://www.wikipedia.org/wiki/Avi_Loeb#%CA%BBOumuamua)

~~~
s1artibartfast
Paper:
[https://iopscience.iop.org/article/10.3847/2041-8213/abab0c/...](https://iopscience.iop.org/article/10.3847/2041-8213/abab0c/pdf)

------
joe_the_user
There are so many questions and so little data.

Oumuamua as the space junk of an extra-terrestial society naturally appeals to
me even if it's not a legitimate guess (I understand that technological
artifact is only a legitimate guess if all other options are exhausted, Ok).

One question would be whether the "axiom of mediocrity" implies that
Oumuamua's flyby of the sun was not the object's first flyby. Logically, if
objects that can survive a million encounter with stars exist, they would seem
a million times more common than objects that could survive one. Which would
also be why you'd be more likely to find space junk than a working space
craft.

~~~
beamatronic
Would an advanced star-faring society make a spacecraft out of anything other
than objects that are already moving? Asteroids and such. This way you don’t
have to lift any mass out of a gravity well.

~~~
CarbyAu
I absolutely don't know much, so question here:

Why is it assumed that a "star faring society" must originate from a place of
significant gravity?

I can understand heat and some way to gather the required chemicals
(primordial ooze) together is required. But does it require much gravity
really?

~~~
zdragnar
Well, life as we know it relies on carbon (energy storage), oxygen (energy
activation) and liquid water (oxygen and chemical transfer).

Setting aside the quandary of sufficient mass to support life evolution and
development from 0 => faster-than-light (or some other interstellar) travel,
there's the problem of liquid water. The lower the pressure it is under, the
more quickly it will evaporate or even boil. Not only that, but dissolved
gasses within the water will also boil out.

So, we're left with either imagining some means of having a large quantity and
volume of mass configured in a way that maintains pressure without gravity, OR
identifying an alternative set of chemicals for the properties that carbon,
oxygen and water currently fulfill.

Water is especially useful due to being a dipole, and there are several other
known compounds that are as well, but they are significantly more complex. I'm
definitely not super informed in this area, but my understanding is there
really aren't other options that are readily found in nature in regular
quantities.

~~~
ajuc
I've read a sci-fi story set on a cold planet where methane was fulfilling the
role of water. There were methane rivers, seas, it was falling in rain, and it
was the basis for all the chemistry.

It sounded reasonable, but I'm not good enough with science to know if it was
legit.

~~~
zdragnar
One thing i overlooked earlier is water's propensity to form acids and bases,
which support all sorts of useful biological functions. Methane's hydrogen
atoms are tightly bound and methane itself is has no dipole moment- meaning it
may have the same physical phases as water, but I am skeptical that it could
fully support life as a substitute.

...not to mention that you also have to do away with an oxygen rich atmosphere
as well...

------
credit_guy
The main question here is not whether Oumuamua was a hydrogen iceberg, but
rather whether hydrogen icebergs are possible.

Solid hydrogen is terribly difficult to study [1]. Solid hydrogen does not
exist at pressures below 100 GPa (i.e. 1 million times higher than the
atmospheric pressure). These pressures occur deep inside Jupiter, for example,
but how do you get the "hydrogen iceberg" free?

[1]
[https://en.wikipedia.org/wiki/Solid_hydrogen](https://en.wikipedia.org/wiki/Solid_hydrogen)

------
The_rationalist
Betteridge law strike again

~~~
happytoexplain
Does it? The article seems to bear out the headline: That the matter is an
active question.

~~~
The_rationalist
According to 2020 in science (the Wikipedia article) Astronomers report that
the interstellar object ʻOumuamua (1I/2017 U1) is not likely to have been
composed of frozen hydrogen which had been proposed earlier; the compositional
nature of the object continues to be unknown.[127][128] So?

