Other side of the Moon would impose unnecessary communication complexities without much optical benefit. Earth-Sun L2 point is much better because Earth's shadow blocks most of heat from the Sun, plus the probe needs heat shield only on one side to block remains of heat from Sun, Earth and Moon. See: https://en.wikipedia.org/wiki/James_Webb_Space_Telescope#Sun...

building on the surface of the moon is not without benefit. as a static location, it would be much easier to build larger sensors with larger mirrors, rather than having to build one giant thing and hope it deploys safely. You could build an arbitrarily large-sized mirror. Or, you could build large radio telescopes that do not need to contest with the noise of the earth's atmosphere.

all spectra are important for astrological observations—there is a serious lack of radio observations made with large telescopes outside of the earth's atmosphere in particular.

NASA has funded an early study into the feasibility of building such a telescope. https://www.nasa.gov/directorates/spacetech/niac/2020_Phase_...

Absolutely, but that still is far much more investment into infrastructure. However the Moon surface is still too hot for precise IR observations.

I'm sure it is on the list for JWST. I suspect Spitzer must have already attempted the same thing.

Being on the other side of the Moon, alone, isn't likely to make a huge difference in image depth.

And frightening. Such photos really bring home the Great Silence. All of those specks which are entire galaxies, and not the single slightest sign of intelligent life anywhere, ever. The marbles roll on just as they have for billions and billions of years and will go on rolling for billions to come, dead pieces of inert matter tracing out their gravitational trajectories and burning as predicted.

>All of those specks which are entire galaxies, and not the single slightest sign of intelligent life anywhere, ever.

You say that as if we could tell with any certainty, at that scale. There could be interstellar civilizations spanning several of those galaxies and uncountable intelligent civilizations that simply never pursued space travel or the constant accelerated curve of energy consumption and colonization we assume they would, only because we ourselves would.

We wouldn't know, we don't even really know what we're looking for, and the universe is so vast that even if we did, we'd be all but certain to blink and miss it.

It isn't even clear that the pursuit of colonization we want to pursue is even possible. It takes a lot of energy to do those things and there are limits to how much we can safely use. We are already worried about global warming despite not having a colony to support.

Yea, but they would have to blink a significant portion of their galaxy for us to notice.

The top of our capabilities is indirect planet discovery. So alien civilization would need to affect ceartain stars on a scale that a planet does and make it look not natural, like prime number periods or something.

This is like being in a plane at cruising altitude, looking down at the ocean, and declaring there's zero signs of life, so the ocean must be dead.

Whales would be visible, along with all the life chemicals, so the analogy isnt that great.

I've flown in planes a handful of times, looked down at the ocean on plenty of opportunities, and never observed any whales. I'd say the analogy is perfectly great.

If the water was as transparent as space, whales and large schools of fish would certainly be apparent.

Space isn't quite transparent, and a closer analogy would be to ask if you can spot bacteria and other microorganisms because something sentient the size of a whale "scaled up to space" would be unrecognizable as such to us.

> Space isn't quite transparent

On Earth scale it is for all practical purposes.

Space whales!

A rather apt analogy, because you can see countless signs of non-equilibrium behavior, chemicals, heat, and other things (you really have never seen any, say, birds while flying?) that tells you you are not on a planet devoid of life.

Assume we are starting with, IIRC, ballpark 14 billion years since the big bang.

Well, to get to life, we have to have chemical elements more than just the hydrogen, helium, and a little lithium that came directly from the big bang. So for carbon, oxygen, ..., iron, have to have some big stars form, burn, and explode.

So those galaxies from 12 billion years ago didn't have much time -- ballpark only 2 billion years -- to form the elements of the periodic table.

Coming at it from our end, IIRC our planet and solar system are about 5 billion years old.

Give it, after the big bang, 4 billion years to the periodic table and another 5 billion years for life. So, that's 9 billion years, 5 billion years ago.

So don't expect much in Little Green Men ET from more than 5 billion years ago.

Since we started 5 billion years ago, we are ballpark only second generation life in this universe.

Net, mostly what's in the Hubble deep field images is too old to have much in life (anything like ours). To have a shot at seeing life, don't look back more than ballpark 5 billion years.

Since stars are burning out and the universe is expanding, are we also about the last generation of life?

Yup, it's amazing to look back 12 billion years, to see galaxies already there, with quasars and, thus, likely supermassive black holes. Amazing to guess how such big black holes formed so soon. Lots more that's amazing. Still for life, only look back about 5 billion years.

Disclosure: I'm not an astronomer!

>Since stars are burning out and the universe is expanding, are we also about the last generation of life?

Red dwarfs will still be burning a trillion years from now. The flare stars among them will only become more stable with time. I'm not sure what the prospects for interstellar travel will be by then, though.

> Still for life, only look back about 5 billion years.

This contradicts the clue of the article. Sometimes it is worth to step back and try something unordinary, especially in area where our assumptions are so weak - the Universe.

Even if we wanted to tell the universe we existed, it would take too much energy to shoot out a strong enough signal. We would have to eat the sun to do that :)

Could I say that it's also hopeful in a way, that nobody more violent than us seems to have emerged?

Well, if they have, they would probably have bombed their civilizations into extinction already.

No, the speed of light is too slow for them to do anything about us.