I think this is worth your reading, and you'll see at least a couple of reasons you can't use "I am taking the silence of the skies as the proof that there is no abiogenesis at all" (e.g. like the detectability issue as I quote an example of at the end of this post), but don't worry, there are yet
more reasons to think we are in a profound way singular (more so than so many wish to imagine).
I'd not be surprised in the afterlife to learn we were the only planet in our galaxy (and even our Universe) with an
advanced intelligent life forms (like us at least in some ways, with language and technology), but that's my own speculation.
To those who believe -- Only advanced life forms could even imaginably host a 'soul' as we experience one.
Microbes do not so far as I understand. Worms don't. Fish don't, I believe. No God-given soul means life matter that is soulless, like bacteria.... Just Biomass. Soulless. Not much different than grass.
But
some people will want to consider the fun notion of life on other worlds, and that's our subject. Please know I won't waste you time below, and have something useful to offer, including a bit at the end.
Based on what I've learned in astrophysics articles, I'd be delighted for us to find even 1 single twin Earth that has both land and standing water bodies and rain and temperate regions and has remained so for billions of years, and isn't bombarded often, and isn't sterilized by UV radiation from a nearby red dwarf, and isn't in transition of migrating closer and closer or further and further away from it's star.
Any numbers are speculative, but "60 sextillion" seems like another of those wild speculation based on not just 2 or 3, but more like 10 to 15 assumptions that are speculations themselves, and unlikely to be turn out to be situations you would actually
like if you were on such a planet....
For example, one way to get a number is to merely speculate on the number of planets in a galaxy or in the Universe that might have liquid water.
Well, that by itself is only one of at least 15 crucial factors for being life-friendly for advanced intelligent lifeforms (and other areas of knowledge I am less familiar with than astrophysics could add more factors perhaps).
For instance, a planetary surface heavily irradiated by ultraviolet radiation because it's near a red dwarf star -- which are like 3/4ths of all the stars in the Milky Way galaxy, our galaxy -- you know UV is a very good way to sterilize something having bacteria, and make the microbes nice and dead.... Not a nice place for people like us, with hands which we think evolved (some of us think this was God's plan; perhaps convergent evolution to an intended vessel to house a soul).
To have liquid water a planet orbiting a little red dwarf star must be
close.
But these little stars, which are most stars that exist, radiate a
lot of UV!
Where is the life supposed to get started on such a planet? Well perhaps far down in the water? That might work for a while, until that planet gets slammed by an asteroid and it's all over. But if protected by a gas giant, that's better, less impacts, and then the planet
will migrate (because of that same gas giant!) too close or too far from its star, unless it's stabilized by the very lucky right combination of other planets in the system, or the life might get a little ways until it gets sterilized by yet another 6 or 10 or 12 mile wide asteroid collision....etc.
So what is "Earth like" precisely?
I'd say it has to be a planet on which favorable conditions continue for not merely tens of thousands or a merely a million years or 50 million. No. Billions of years are needed for much evolution to progress, according to our own view of what happened on Earth in mainstream science.
But....let's do some wild speculation and
imagine there was indeed an actual Earth like planet of the kind you could actually survive on yourself (let's say you are immune to the flora there), and it was a mere 5,000 light years away....
Fun!
Well.....
Here's something that may it may help to know which I just searched up wondering about the magnitudes of detectability of something like radio waves in practical terms -- could we detect them if they were broadcasting like we do....:
"The SETI Phoenix project was the most advanced search for radio signals from other intelligent life. Quoting from Cullers et al. (2000): "Typical signals, as opposed to our strongest signals fall below the detection threshold of most surveys, even if the signal were to originate from the nearest star". Quoting from Tarter (2001): "At current levels of sensitivity, targeted microwave searches could detect the equivalent power of strong TV transmitters at a distance of 1 light year (within which there are no other stars)...".
From how far away could Earth's telescopes detect Earth like radio signals?
People don't really realize usually how far apart stars are, how big the Milky way is, etc., and they can imagine it's merely like picking up a signal (what is actually a beamed and focused signal btw!) from a probe like we sent past Pluto. Nope....
So, while I'm guessing no such civilizations are likely to be anywhere close, like anywhere closer than thousands of light years, still even if one was a mere shockingly close 10 or 50 light years away (like our immediate neighborhood -- like right next door compared to the size of the Milky Way....!), we could
not detect broadcasting they would do like our own style of broadcasting at this time.....
heh heh