
New study dramatically narrows the search for advanced life in the universe - dnetesn
https://phys.org/news/2019-06-narrows-advanced-life-universe.html
======
papito
Most of the Universe is uninhabitable. People keep talking about the
"Goldilocks Zone" but that is just _one_ factor.

* We are on the outskirts of the Milky Way because the center of the galaxy is radiation hell. A chunk of most galaxies is too "hot" for life. So take most of the SPACE out there and move that to the side.

* The planet itself has to be around a star that's not too big and not too dim, at the right distance, of course.

* Our Solar system is very special as it has the planets in stable, almost circular orbits around a SINGLE star. It's not "collision central", where most planets can still smash into each other, within a binary star system, to boot.

* We have gas giants, by chance, protecting us against space rocks flying into us.

* The Moon, just the right size, just the right distance, to keep us in stable rotation, with seasons.

* Just the right amount of water. Too much or too little water, and we would not be here.

* I am probably missing a bunch...

* And only then you get to the rest of the factors for life to be possible.

~~~
godson_drafty
* an iron core that produces a magnetic field surrounding the planet, which allows the atmosphere to remain in place, rather than being blasted off the planet by solar winds.

~~~
Mirioron
Not only that - the outer core is also molten to a large degree. Without it,
we wouldn't get such a strong dynamo effect.

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julius_set
I mean that’s all well and dandy but as the article itself mentions: “these
parameters are toxic to human and animal life on Earth.”

Your definition and data for life is only the current life on Earth, since we
don’t have a clear understanding of other types of life in the universe we
cannot fully support this hypothesis.

~~~
rdiddly
Yep, all the obvious disclaimers apply regarding the acid-breathing snail-
people of Xebron 5...

~~~
ddxxdd
I prefer to imagine alien life as a sentient sludge with internal electrical
signals as complex as the human brain, but with no notion of "self",
"emotion", "purpose", "language", or other silly human things.

Heck, what's stopping us from classifying ocean currents as a sentient
lifeform?

~~~
sweetheart
You should read Children of Time and then Children of Ruin.

~~~
1_player
I second the recommendation. Children of Time is my all-time favourite sci-
fi/alien life novel.

Can't wait to finish what I'm reading currently to get started on Children of
Ruin.

------
gjm11
The phys.org article just reproduces (while adding a bunch of irrelevant
internal links and some advertisements) the university's press release here:
[https://news.ucr.edu/articles/2019/06/10/new-study-
dramatica...](https://news.ucr.edu/articles/2019/06/10/new-study-dramatically-
narrows-search-advanced-life-universe)

and the actual paper is here:
[https://iopscience.iop.org/article/10.3847/1538-4357/ab1d52](https://iopscience.iop.org/article/10.3847/1538-4357/ab1d52)

phys.org: just say no.

~~~
justfor1comment
I don't know why an organization called phys.org might need such
sensationalization of mundane news. Every article including this one makes it
sound like new developments have occurred in physics. When you actually read
the article and apply a small helping of skepticism you realize, the world is
just the way it was yesterday. phys.org is not HN worthy imho.

~~~
pergadad
Well they too need clicks. Set the right inventive (people more likely click
bait links than more sound/dry ones) and it will either go that way or lose
out to another org that does.

It's like sitcoms with laugh tracks. Everyone you ask hates them, but if you
ask people how much they enjoyed/would rewatch/would recommend/... a certain
show they consistently give higher ratings to an episode with vs without
canned or study laughter.

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maxander
Several bars of CO2 are inhospitable to life evolved in an atmosphere of
several hundred ppm of CO2, sure, but are there arguments that high levels of
CO2 would be detrimental most possible lifeforms out there?

(CO is much more reactive, but it's harmful _to us_ because it reacts to our
hemoglobin in much the same way as oxygen. So since Earth life has managed to
get on just fine with all this corrosive oxygen around, the same argument may
still apply.)

~~~
yread
Maybe they're looking at us and think "What 21% O2? Surely no life could exist
there, everything would just burn down immediately!"

EDIT: "Especially in combination with water vapour in atmosphere - it would
freeze, static charge would build up between the ice particles and the
discharge would ignite everything. Indeed the fact that O2 is so high is a
proof that there is nothing left to burn"

~~~
ddxxdd
>Maybe they're looking at us and think "What 21% O2? Surely no life could
exist there, everything would just burn down immediately!"

I swear, this is an exact line from a Ray Bradbury story that I read as a
child.

~~~
mannykannot
Also Clarke, in the title essay of 'Report on Planet Three'. The flaw in this
argument is that an out-of-equilibrium concentration of oxygen implies a
process to maintain it.

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hurrdurr2
This study seems rather self limiting (but then again I'm no biologist)...
what if there are non-carbon based life that does not care about carbon
dioxide or carbon monoxide?

~~~
hurrdurr2
This is off topic, but I am almost done with the book The Dark Forest, and the
concept kind of terrifies me regarding extraterrestrial life.

~~~
djohnston
we just need to stay quiet

~~~
andrewflnr
Yeah, Voyager's already gone, it's too late.

~~~
quotemstr
Voyager is also very slow and will soon be very cold. I wouldn't worry. The
book's premise relies on fictional physics pretty far from anything we know in
the real world --- things that would cause all sorts of thermodynamic and
information-theoretic havoc --- so I wouldn't worry.

------
ianai
This still sounds like an overly pessimistic crowd of suppositions. I was
hoping for inferences into planetary atmospheres. It’s probably mostly
impossible, but I think I’ve seen estimates on some of these planets
atmospheres. Until, if we can ever, measure what’s in the atmospheres of these
planets we’re really stretching it.

------
MichaelMoser123
What happened to the theory that you need a moon with its tides? Is that still
credible or is it not? [https://www.scientificamerican.com/article/moon-life-
tides/](https://www.scientificamerican.com/article/moon-life-tides/)

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idlewords
This study makes extensive assumptions about life on other planets being
earthlike. Boy will we have egg on our face when the xenonauts land on earth
with their breathing tanks full of carbon monoxide.

~~~
andrewflnr
I'd be curious to see an outline of a metabolism based on CO. Can you build an
analogue of hemoglobin that behaves nicely with CO?

~~~
hoseja
Who says there has to be anything resembling hemoglobin? Or blood? All this
xenobiology is so shortsighted.

~~~
andrewflnr
Circulating fluids are super convenient for moving chemicals around. Plants
use them, too. I would be very surprised if there wasn't at least an analogue
for blood.

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YeGoblynQueenne
This is extremely human- and Earth- centric. It's as if the only life we're
interested in finding in the universe -the _entire_ universe- is life
identical to life on Earth. Life that needs an environment just like Earth,
and can't survive in any environment that is not like Earth. Life that even
has hemoglobin! How likely is it that all life in the universe _must_ be like
life on Earth? Actually, by the study reported in the above article- very
unlikely.

Anyway, I'm reminded by this quote by Douglas Adams (veers off to something
else entirely but it starts very relevant):

 _Imagine a puddle waking up one morning and thinking, "This is an interesting
world I find myself in — an interesting hole I find myself in — fits me rather
neatly, doesn't it? In fact it fits me staggeringly well, may have been made
to have me in it!" This is such a powerful idea that as the sun rises in the
sky and the air heats up and as, gradually, the puddle gets smaller and
smaller, it's still frantically hanging on to the notion that everything's
going to be alright, because this world was meant to have him in it, was built
to have him in it; so the moment he disappears catches him rather by surprise.
I think this may be something we need to be on the watch out for. We all know
that at some point in the future the Universe will come to an end and at some
other point, considerably in advance from that but still not immediately
pressing, the sun will explode. We feel there's plenty of time to worry about
that, but on the other hand that's a very dangerous thing to say. _

[https://en.wikiquote.org/wiki/Douglas_Adams](https://en.wikiquote.org/wiki/Douglas_Adams)

------
sktrdie
I think life (event from chemistry to biochemistry) is rare because we can
think of each planet as a specific combination of chemistry composition. All
these combinations, even if they exist in the order of billions, is still a
limited amount of possible combinations of chemical properties.

In a lab we can reproduce these combinations in ideally a much greater number.
So my insight is that we can create chemical processes in a lab at a much
higher rate and with much more interesting combinations that nature can. And
still life hasn't arose in the lab.

This seems to me like a sensible experiment that can somewhat prove that if we
can't do it in the lab, where we're free to combine whatever we want, then why
should it be "easy" for nature with its limited amount of combinations.

~~~
vikramkr
Because nature has way more time and space than we do. And life hasn't arisen
in the lab (on earth by humans at least) yet, but it's certainly arisen in
nature at least once, so those factors seem to clearly outweigh our ability to
experiment

~~~
agumonkey
But Nature doesn't optimize for life. It had billions of years and insane
amount of space to do whatever.

We ~may be able to focus search on life sustaining chemical combinations ?

~~~
vikramkr
Nature does optimize for life because by definition the result of any
optimization is life. Natural selection is a powerful force. And with time,
nature optimizes for chemical reactions that self replicate without the biases
and weaknesses of human science. We aren't patient enough to wait as long as
nature is willing to and we are biased because we keep trying to replicate
life like ours. Nature also had panspermia and other techniques to spread life
around once it gets going, it only needs to figure it out like once per galaxy
under some sets of assumptions

~~~
agumonkey
Yeah but optimization is not linear, earth gave way to a path to lifeforms,
other places not so much, they end up lifeless local maxima. Saying space and
time can't be a simple factor to dismiss local human research.

------
pharrington
link to actual study:
[https://iopscience.iop.org/article/10.3847/1538-4357/ab1d52](https://iopscience.iop.org/article/10.3847/1538-4357/ab1d52)

------
mxcrossb
Coincidentally, a paper was published today in Reviews of Modern Physics on
this topic:

[https://link.aps.org/doi/10.1103/RevModPhys.91.021002](https://link.aps.org/doi/10.1103/RevModPhys.91.021002)
[https://arxiv.org/abs/1810.02007](https://arxiv.org/abs/1810.02007)

It seems like a fun time for this field

------
dr_dshiv
Arguments for panspermia could go either way. If panspermia is designed, it
might be tailored to a wider range of conditions. If "natural", it is more
likely to have a chemistry like ours, based on the one spurious data point we
have available

------
raxxorrax
So do we have a weakness in processing larger amounts of co2 because we have
low levels in our athmosphere or is this a fundamental problem that
respiratory systems cannot handle? I mean water didn't stop us.

~~~
akvadrako
During the Ordovician period, a few hundred million years ago, CO2
concentrations were around 4,000 - 6,000 ppm, and there was plenty of animal
life.

At the low end, the article is talking about 10,000 ppm (0.01 bar), so not
much higher.

~~~
raxxorrax
Yeah, I would think that is still okay for life. Even if CO2 does displace O2,
I would imagine some adapted respiratory organs could very well deal with that
if the concentration were higher.

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negamax
It's strange to make this hypothesis. We know so little about life. What if
life can exists anywhere and can _adapt_ to its environment. Even the complex
one

~~~
nurettin
What scientists appear to be telling us is that this is "life as we know it",
without delving much into the details of what life could constitute of. And
that conventional definition of life, which requires very specific aminoacids
to co-exist, is pretty much dependent on certain mixes of humidity and
temperature and certain gases are toxic to it in general.

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vixen99
"...high concentrations of carbon monoxide, another deadly gas" could have
been phrased rather differently given that this 'deadly gas' is essential for
life on earth at around >150ppm or so and without which almost all plants
would die in short order never mind that respiration likewise for plants and
animals involves its excretion along with water. There is no such thing as a
single chemical substance that is <not> toxic for life forms at some
concentration. Yes, there are optimum levels for all of them - in some cases
down to almost zero.

------
mensetmanusman
What if future humans check all the planets in the universe and find no other
life

~~~
turingbike
> What if future humans check all the planets in the universe

Nope! Imagine a shell around us, defined as "how far we could go, if we left
right now, traveling at near the speed of light, given that the accelerated
expansion of the universe keeps making things get further away." It's a large,
but finite, sphere. It's actually smaller than the Cosmological Event Horizon
[0], which is the cutoff point, beyond which light can never reach us (again,
because the accelerated expansion of the universe is effectively putting space
between us and the event faster than light can travel) - estimated to be ~ 16
billion light years in radius.

If by "universe" you meant "observable universe" \- that's fair, but still no.
How long could humans conceivably last before we go extinct, or change into
something that can't be called human anymore? I feel like 100,000 years is an
absurdly high estimate, but let's got 10x higher.

If we figure out how to travel at c/2 soonish, and we say going somewhere
counts as "exploring" (no need to report back to any one), then we have a
~500,000 light year radius sphere to explore. That's ~ 225 billion stars. For
the near ones, we can shuttle back and forth, but for the far ones, that's a
one way trip. So let's say 100 billion space ships. And that's if we leave
tomorrow.

c/2, 100 billion space ships... If we start paring these back to reasonable
figures, you start to realize: our species will barely scratch the surface of
the observable universe. In 1,000,000 years, I think, best case, we can cover
a 50,000 light year radius sphere. That's 0.000000000000003% of the observable
universe.

[0]
[https://en.wikipedia.org/wiki/Cosmological_horizon](https://en.wikipedia.org/wiki/Cosmological_horizon)

~~~
seattle_spring
> That's 0.000000000000003% of the observable universe.

Also coincidentally the percentage of equity most startups grant engineers.

~~~
raxxorrax
But they get to breath co2 deprived air. Young people are just always
complaining.

