
A Trillion Worlds - okket
https://blogs.scientificamerican.com/observations/a-trillion-worlds/
======
jerf
So, this is actually a big deal, in the "centuries-long arc of science" sense.
For hundreds of years, science has operated under the Copernican Principle
[1], which in a nutshell is that there is nothing particular special/unique
about us. Our position on the planet is not special. Our planet is not
special. Our solar system is not special. Our galaxy is not special, etc. It
has been a scientifically-fruitful tool for a very long time. It has even
embedded itself into the "default worldview" of the scientifically minded as a
law of the universe.

But it was never more than a heuristic, and the data is increasingly coming in
that the Copernican Principle breaks down at the solar system scale. In fact
our Solar System is at least somewhat rare. It is certainly possible that the
more we study the rarer it will become. (It can't really go the other
direction at this point.)

It's going to take decades for this to properly percolate through the
philosophy of science and its implications to be properly chewed on for a lot
of the Big Questions.

(Note I'm not making any claims about the outcome of that process here; any
such things you read into this are your own worldview poking out. I'm just
saying, this is a really big event in the history of science. The sort of
result that 23rd century textbooks are going to be calling out in the primary
text as an important event.)

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

~~~
kingbirdy
> It can't really go the other direction at this point

What makes you say this? As I understand it, we've only detected a tiny
fraction of the planets out there and it could be that there are plenty of
systems out there similar to ours, we're just not capable of seeing them yet.
Is there some reason to believe we're unlikely to ever see another system like
ours, other than the fact that we haven't yet?

~~~
dforrestwilson
I am always skeptical of these vast sweeping assumptions about a Universe
which we have not even started to seriously explore.

Based on the best available scientific tools at the time, we once thought that
the solar system rotated around the earth.

Based on the best scientific tools available today, we believe that our solar
system and planet is extremely unique.

I think we don’t know nearly enough to say with any real confidence what solar
systems outside of ours look like at this point.

~~~
jerf
The sibling comment to yours is correct in its logic in inferring what I
meant.

It is true that we are ignorant of many things. It is not true that our
ignorance is infinitely unbounded, and it is a denial of science and
rationality, not an affirmation of it, to believe such. We have gathered
enough data that we already know that our solar system is not perfectly
pedestrian, and no amount of additional data short of the outright
falsification of our current data (which, bear in mind, is a bigger ask than a
falsification of a _theory_ , which isn't much of an ask at all) can make it
_more_ pedestrian; it can only reveal more ways in which it is not normal.

~~~
ta1234567890
> It is not true that our ignorance is infinitely unbounded

Well, if you define our ignorance as information we don't yet have. Then if
the Universe is infinite, it means our ignorance is unbounded.

In fact, if any type of infinity exists, then it means in general our
ignorance is unbounded, because we will never be able to have full knowledge
of that infinity.

For example, you can make as many assumptions as you want about the properties
of the rational numbers in between two other numbers, but unless you are able
to somehow "know" all of those numbers, then your ignorance about them is in
part bounded by their quantity, and if it there's an infinite amount of them,
your ignorance about them will be unbounded.

------
shmageggy
I would have liked to hear about how they are now accounting for the inherent
bias of our detection process to find large, close-to-star planets, because
those are the ones that produce the best signals. I remember that that used to
be a big issue in drawing any statistical conclusions about expolanet data.
Has there just finally been enough data collected that we can model our own
bias?

~~~
adminonymous
Along the lines of this "detection bias," I've long wondered if there's
another bias: the orbital angle of the exoplanets with respect to the plane of
ours. If the detection is based on transit across the star of the system, what
if we're looking at the axis of the planetary system, and not its equator? All
systems similarly oriented toward our instruments would come up as a false
negative, no? (I'm not an astronomer, please correct my jargon).

~~~
wlesieutre
You're correct that most of our detection is by transits in front of stars and
will only see planets with orbital planes aligned toward us.

However, it's _super cool_ to note that we've actually directly imaged
expoplanets orbiting around their stars in other planes:
[https://en.wikipedia.org/wiki/List_of_directly_imaged_exopla...](https://en.wikipedia.org/wiki/List_of_directly_imaged_exoplanets)

Another possibility is detecting planets by the wobble that they introduce in
the star's position. I'm not well read on the subject, but I wonder if Gaia's
position measurements via parallax are accurate enough for this.

EDIT: A bunch more information from Wikipedia on detection methods
[https://en.wikipedia.org/wiki/Methods_of_detecting_exoplanet...](https://en.wikipedia.org/wiki/Methods_of_detecting_exoplanets)

 _The space-based observatory Gaia, launched in 2013, is expected to find
thousands of planets via astrometry, but prior to the launch of Gaia, no
planet detected by astrometry had been confirmed._

------
brianberns
> Half of nearby stars have at least one (and often several) worlds with
> masses substantially greater than Earth and orbital periods ranging from
> mere days to weeks

Perhaps it just seems like such large inner exoplanets are so common because
they're easier to find with our current techniques?

~~~
samatman
It says "half of nearby stars"

That's common. It's half!

They're also easier to find, sure. Maybe the other half are exactly like Sol
but we can't tell yet.

But nothing can make 1 out of 2 stars near enough to make out into something
uncommon, except our local cluster of stars itself being weird in some way.
Which is possible.

~~~
ianai
To me, that sounds like the Star forming process often results in masses below
critical orbiting formed stars. I’m wondering whether they’re all gaseous. It
also seems a little too uniform to believe without much more study. We could
easily find out these sorts of systems have asteroid belts and planets at a
farther distance than we can easily detect.

Or maybe the failed stars failed because they suck up the metals in the system
(anything past helium in this sentence).

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cpeterso
If you are interested in exoplanets, I recommend Adam Frank's book _" Light of
the Stars: Alien Worlds and the Fate of the Earth"_. He discusses the history
of the Fermi Paradox, the Drake Equation, and how what we know about
exoplanets can inform us about Earth's history and future.

[https://smile.amazon.com/dp/0393609014](https://smile.amazon.com/dp/0393609014)

------
bpd1069
I wonder if there is any models exploring the possibility that our system is
uncommon due to 2 systems merging? IOW, Sol ejected a companion star and
assimilated the planets from the other.

~~~
Ultimatt
Or Jupiter is just the failed to to get big and ignite companion and there are
models for that.

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nerdponx
Off-topic, but I really appreciate that they offer "Cookie Settings", giving
me the option to disable ad-tracking cookies. Yes, the button is almost
invisible gray-on-gray, but it's there. Is this the GDPR showing its usefuless
already?

~~~
andreygrehov
Yep. I've seen it a lot lately. Most of them are powered by a third-party
service. This one is coming from
[https://www.onetrust.com/products/cookies/](https://www.onetrust.com/products/cookies/).

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hamilyon2
Could this mean the great filter is likely behind us?

~~~
cobbzilla
It's likely there is no great filter; there exist reasonable claims that the
Fermi Paradox has been "dissolved" [1] [2].

[1]
[https://news.ycombinator.com/item?id=17302924](https://news.ycombinator.com/item?id=17302924)

[2]
[https://news.ycombinator.com/item?id=17560462](https://news.ycombinator.com/item?id=17560462)

~~~
fbreton
If I understand this study correctly, their conclusion is that it is likely
that intelligent species are very rare in the universe. This still implies a
"Great Filter", but it would have to be behind us.

~~~
logfromblammo
We're only about 5.5 billion years away from intelligent species being either
very common in this galaxy, or completely nonexistent.

Which is to say that we need to start building interstellar transport vessels
soon.

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mrfusion
I would think most of their findings are related to the types of exoplanet
detection methods we have.

Talk to my when you’ve detected all planets in a random representative sample
of stars.

