
Observable Universe contains 10x more galaxies than previously thought (2016) - mkempe
https://www.spacetelescope.org/news/heic1620/?lang
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Razengan
And some people _still_ aren’t sure if there is other life beyond Earth. :)

That's entire _galaxies._ Not just stars, and that's just the _observable_
universe.

We are still being surprised by the lifeforms we observe here on Earth, and
the environments and conditions they can thrive in (including the outer hulls
of our spacecraft), and we still have yet to discover and catalog all the life
on our planet. Life may even come in the form of "artificial" constructs that
build, learn, teach and reproduce on their own, created by "natural" life
somewhere then set free into the cosmos.

How, when given the evidence of practically infinite planets out there
(considering that almost every star may have at least one planet, and there
are even rogue planets [0] that don't orbit any star, and that asteroids and
comets or even dense nebulas could also harbor life), can we even consider the
possibility that this is the only planet with life?

This game is Big, folks: _Even if 90% of all planets had life there would
still be billions if not trillions of them without any life_ , and the
incomprehensibly vast distances (including voids, like the one our own galaxy
is near or inside of [1]) between them may mean millions of years before life
from one planet encounters life from another (which is good I suppose; every
species would have some room to expand into at their own pace.)

And of course, not all intelligent civilizations will be "successful."

We will either die out on our home planet or expand.

We may not encounter other life for hundreds or even thousands of year after
we develop interstellar travel, or the life that we encounter may turn out to
be mundane and eventually unexciting (I mean, imagine being an spacefaring
species discovering us; planetlocked and still collectively figuring many
basic things out.)

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

[1]
[https://en.wikipedia.org/wiki/Milky_Way#Environment](https://en.wikipedia.org/wiki/Milky_Way#Environment)

~~~
V-2
> _How, when given the evidence of practically infinite planets out there
> [...] can we even consider the possibility that this is the only planet with
> life?_

Human minds aren't good with very large numbers. What seems "practically
infinite" to us - isn't, really.

The number of all planets in the universe is said to be in the ballpark of
10^24.

Meaning (obviously) if you keep on dividing it by 10, in just 24 steps you get
down to 1.

Meaning if there are 24 factors crucial for life to evolve, and each has a 10%
chance of occurring - it's actually quite likely only one planet would win on
this lottery. (At a given point in time, that is - that's another aspect of
course).

Or 12 factors, but each with a 1% chance. And suddenly it doesn't seem like a
number big enough to warrant certainty claims...

Basically it is the "wheat and chessboard" problem in reverse.

You start with a huge pile of planets, but once you start splitting the pile,
it shrinks very very fast.

Personally I'm not _sure_ either way, and I think being sure (either way) is
just naive.

I _believe_ there is microbial life out there, and I accept a slim chance we
may actually discover it - say, over the course of the next few centuries -
but I'm sceptical about the existence of intelligent life, and even if it did
exist, I see the chances of any contact to ever occur as zero.

~~~
esarbe
I agree with you in that we will probably never have contact with another
sentient species of extra terrestrial origin. The distances are to vast, the
lifetimes of civilisations and even species too short and so on.

However I do think that you vastly underestimate the probability of life. Take
a look at
[https://en.wikipedia.org/wiki/Earliest_known_life_forms](https://en.wikipedia.org/wiki/Earliest_known_life_forms)
. See how quickly life appeared once the earth had cooled down? It's almost
immediately!

I'm pretty convinced that almost all star systems have some complex energy
conversion cycles that could be classified as life. Let's not make the mistake
of assuming all life has to be carbon based.

~~~
blauditore
But it's fairly likely to be carbon-based, as carbon is the simplest existing
element with the maximum amount of valence electrons. And generally, simpler
(= lower ordinal number) means more stable, as well as more likely to arise
(as less energy is required, e.g. in stars).

~~~
zamalek
There are other theoretical biochemistry possibilities[1]. Silicon, for
example, works well in low-pressure environments. It's an immense stretch of
the imagination to think about life-forms that use semiconductors to do useful
work, but is certainly a fun thought experiment.

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

~~~
blauditore
Yes, it's possible, just less likely. How much less likely is hard to tell,
but I if you hear hoofsteps, you first think of horses, not zebras.

------
ttoinou
I think other lifeforms exist in the universe, but the probability that they
live in the same timeframe or that the two lifeforms meet each others is
ridiculous

~~~
olegkikin
Vlad the Astrophysicist

[https://www.youtube.com/watch?v=o9kbcGfX35M](https://www.youtube.com/watch?v=o9kbcGfX35M)

------
almavi
I don't understand. They say the observable universe contains 10x more
galaxies than previously thought, and the reason for that is the concentration
of galaxies being greater in the part of the universe that our telescopes
can't see?

~~~
andyjohnson0
The Observable Universe is the part of the total universe that we can
_theoretically_ observe because electromagnetic radiation from it has had time
to reach us. In practice, some of this radiation will be detectable with
current technology and some of it will be too faint.

The article is about work, using models of galaxy formation, that tries to
better estimate the number of galaxies we can't detect due to limits on
telescope sensitivity, but which are nevertheless theoretically observable.

It might be useful to describe the detectable part of the observable universe
as the "visible universe", but astronomers have a different meaning for that.
See
[https://en.wikipedia.org/wiki/Observable_universe](https://en.wikipedia.org/wiki/Observable_universe).

~~~
almavi
Yeah, I understand this now, thanks.

------
kulu2002
Like Carl Sagan rightly said - "Cosmos is also within us. We're made of star
stuff. We are a way for the cosmos to know itself.” We need to study ourselves
more to comprehend this vastness.. [1]
[https://www.sciencealert.com/physicists-show-that-our-
brains...](https://www.sciencealert.com/physicists-show-that-our-brains-s-
learning-is-controlled-by-entropy)

~~~
luxcem
"Given enough time hydrogen starts to wonder where it came from and where it
is going."

------
dahart
From 2012: "But even the XDF is not optimized for finding these galaxies; we’d
need an infrared space telescope for that, which is what James Webb is going
to be. When that comes around, I wouldn’t be surprised to find that there are
maybe even close to a trillion galaxies in the observable Universe; we just
don’t have the tools to find them all yet. In the meantime, our best tool—the
Hubble Space Telescope—is showing us that the deeper we look, the more we’ll
continue to be rewarded with new, faint, and distant galaxies, as well as
richer details in the already discovered ones.

"It makes me so impatient for a more powerful telescope with the ability to
see far into the infrared, because I can’t help but wonder what’s still
invisible to even the XDF. Twice as many galaxies? Four times? Fainter ones,
redder ones, more distant ones, or all of them? There’s at least 176 billion
of them in our Universe, but I can’t help wonder, “how many more?”"

[http://blogs.discovermagazine.com/crux/2012/10/10/how-
many-g...](http://blogs.discovermagazine.com/crux/2012/10/10/how-many-
galaxies-are-there-in-the-universe-the-redder-we-look-the-more-we-see/)

"It boggles the mind that over 90% of the galaxies in the Universe have yet to
be studied."

Maybe this one's different, but when discussing astronomical terms, a factor
of 10 doesn't ever surprise me. What does surprise me, continuously, is how
many unimaginably large numbers of factors of 10 are involved in anything
related to the size of the universe. There are so many estimated stars in the
universe, it would make little difference to my already boggling mind if our
estimates were off by a factor of a million.

------
pedro_hab
I wonder if this has some impact in our (mis)understarding of dark-
matter/dark-energy, and how the universe expands.

------
0xBA5ED
Staring into those deep field images sometimes gives me an out-of-body
sensation. The vastness of it is so over-the-top.

~~~
mtgx
If looking at a few images gives you that sensation, then you should try out
the Space Engine (traveling through space in 3D):

[http://spaceengine.org/](http://spaceengine.org/)

A demo:

[https://www.youtube.com/watch?v=ve0Bpmx8Fk0](https://www.youtube.com/watch?v=ve0Bpmx8Fk0)

~~~
0xBA5ED
Thanks. I've already played with this and it's awesome.

------
taloft
"The Universe is a pretty big place. If it's just us, seems like an awful
waste of space."

------
rdruxn
I’ve seen a lot of posts recently discussing humanity’s concept of the size of
the cosmos throughout history, but never a timeline of discoveries and the
prevailing estimate du jour. I would love to see something like that and
Wikipedia doesn’t do it justice.

------
mrarjen
Just imagine all the stuff that's not giving off light or anything observable
by us at this time. Rogue planets and what not should be everywhere no?

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arghwhat
... isn't our error margin much larger than this?

------
ngcc_hk
Need less dark mass and dark energy then.

...

~~~
SEMW
No? The data for the makeup of energy in the universe is mostly from CMB
anisotropy (plus various measures of how fast the universe is accelerating,
like how much supernovae have been redshifted). Finding out that galaxies in
the early universe used to be smaller and more numerous than previously
thought doesn't much affect any of that. (there's quite a lot of different
data sources now all pointing towards an omega_lambda of 0.7).

To be clear, per the article, the new discovery isn't about the early universe
being a significantly different density (i.e. anything other than
'approximately flat', total omega ≈ 1) than the current one. Like, it's not
that there was more mass-energy in it that's somehow vanished, rather that
it's just distributed between more & smaller galaxies

