After decades of active SETI searches it’s tempting to say that we appear to be alone.
The problems there however are in the numbers.
In an observable universe that contains, and think about this, 1 followed by 24 zeros,
star systems, it seems unlikely that we would be alone.
That this single planet, in one single galaxy itself among 2 trillion others, would be the
only one with life is beyond unlikely to the point that science itself goes off kilter,
in that there no longer is a mediocrity or copernican principle to rely on.
We’d have to reckon with this planet actually, for some reason, being very special and having
won the highest possible lottery odds in the universe.
If you factor in the universe at large, the flat geometry of it possibly suggesting it’s
infinite in extent, and we assume it’s much the same outside of our observable bubble,
it becomes increasingly impossible to be alone.
In an infinite universe, it simply becomes impossible to be alone given infinite chances
for a second occurrence.
Indeed, it becomes a matter of infinite occurrences at that point.
This leads us to the continuing question.
If intelligent alien life is common, then why don’t we see evidence of it everywhere?
There are obviously many possible answers to this, a great many of which I have covered
on this channel.
But a more recent line of thinking as that may be in our speculations on the solution
to the Fermi Paradox, we’ve missed the simplest answer.
In short, we’ve only recently become interesting.
This of course involves radio.
Many make the argument that the reason SETI hasn’t seen any verifiable technological
signals from alien intelligences is because aliens no longer use radio and instead favor
some other means of communication, perhaps involving physics we don't yet know anything
about.
But this suffers a problem, radio is cheap and easy.
You can emit it without expending too much energy.
This may not be the case with something like gravitational wave communications.
While there may be advantages to it, it may just require too much mass and energy to ever
be practical.
After all, you can roast chicken with a thermonuclear bomb, physics lets you do it, but it comes
with a lot of baggage, when a standard fire the same as we have built since the dawn of
humanity works just as well.
All you need is wood instead of plutonium.
And, fire has never gone obsolete.
Maybe radio never does either, especially with radar which has no really good alternative
in nature.
So why don’t we see alien transmissions everywhere?
The reason may be really simple, there aren’t any powerful transmitters pointed at us.
SETI currently takes shots in the dark, hoping for some leakage of internal communications
that might be powerful enough to see, or coming across an intentional signal by sheer chance.
Newer SETI experiments will be coming online in the future that take a broader approach
and search large swaths of the sky instead of targeted stars.
But they all suffer from the weak signal problem, all alien signals we currently can see might
simply be below our detection threshold.
And, as usual with anything in SETI, we can take a look at our own radio for some insight.
It simply gets weaker and weaker the further you go from earth, and other than some radar,
most of our signals at a distance would be extremely weak.
Aliens may not yet know about us both because of distance, our radio has only propagated
out to a radius of about 100 light years at this point, but also because of our weakness.
Unless someone is monitoring earth 24/7 with an enormous radio telescope, they might just
easily miss us.
In a paper by Amri Wandel, link in the description below, a new take on the Fermi Paradox is
advanced.
In a nutshell, we should expect to see nothing because we’ve just arrived on the scene.
This rests on one reality.
In the past, and in science fiction, we’ve always looked at the big picture for aliens.
Gigantic Kardashev Type III civilizations that control the energy of entire galaxies.
But, there does not seem to be one in this galaxy, it still looks fully natural.
Nor do we see anything in nearby galaxies.
So maybe instead of expecting all powerful aliens, maybe they’re simply practical and
live within their means.
It may simply be that building von Neumann probes are just too expensive in materials
and development, with too many star systems to cover, and that it may be better to just
build very large radio telescopes and listen, especially space based interferometers that
can have an effective size of an entire star system from which to collect very sensitive
data and look for weak signals.
Given the current radio radius of earth’s emissions, it’s entirely possible that the
answer to the Fermi paradox is that no one has seen us yet.
As our signals propagate outward, the chances for being picked up by an alien civilization
rises.
While there may not be anyone within a hundred light years, the chances of there being someone
within a thousand light years is much greater.
Two thousand, far more so.
But that’s not the only issue, the other problem is the return time needed for a message.
This radius is even smaller, so an alien civilization 100 light-years out detects us right now,
and decides to send a signal back.
They may or may not have a transmitter that can do it, so it may take them decades longer
to build it.
Once they’re ready, the soonest we can expect a message back is at least in a century, probably
more.
That’s if they choose to respond at all, rather they may be listeners that play it
safe and go radio silent as best they can once they realize there’s someone else in
their neighborhood.
But with distance comes a degree of safety, if you’re a thousand light years away, then
it’s less likely that sending a hello signal will get you invaded.
But that also means that we have almost 2,000 years before we’ll hear anything from such
a civilization.
So it should not really be surprising that we haven’t heard from an alien civilization
unambiguously in radio, and we should caution against getting too impatient to prematurely
dismiss the paradox.
And, there is another aspect of this, it’s possible that aliens are transmitting in radio,
but using a different means, that’s sat relatively neglected in SETI because it’s
hard to look for.
Conventional wisdom in SETI goes like this.
You pick a frequency that might have some natural signpost that aliens would be aware
of, such as the 21 centimeter hydrogen line.
You then listen with the channels of your receiver sliced into very narrow bands.
You then look for narrowband signals, especially those limited to one channel, and since nature
does not readily produce such signals, if you see one, it’s likely artificial in nature.
But that’s not the only way to make a technological signal.
This second technique is something we might not see even if it were right in front of
us.
In telecommunications there is the concept of spread spectrum technology.
This is a technique where a normally narrowband signal is spread, or smeared across frequencies
having the effect of a wider bandwidth, or jumps around in frequency.
This is really useful in secure communications, and also favors signals against noise, jamming,
interference and so on.
This technology can also be really hard to spot, unless you know very specifically what
you’re looking for.
It’s essentially useful for clandestine communications.
Raw radio telescope data in SETI experiments is messy.
You can see this in the famous Wow signal printout.
The low numbers you see populating the page are noise, anything 3 and below is just not
workable.
Going up from that, 4, maybe something, 5 a little more likely, 6EQUJ5 with a 6 and
a 7 stepping up from the base frequency is ridiculously strong and weird, even if it
were earth interference.
That said, it shows that weak signals will get lost in the noise and other than wow,
the candidate signals have tended to be very weak.
As a result, radio astronomers in SETI built a toolkit to wade through all the noise, such
as the fast fourier transform.
The problem is that these techniques might not readily pick out obscured signals like
spread spectrum.
That may mean we’re simply missing signals because nearby aliens are stealthy.
This may dramatically improve however with the advent of quantum computing and artificial
intelligence.
Those methods might make searches of old data far easier than we can do right now, meaning
that we may have picked up alien signals, we just didn’t have the computing power
to identify them.
It could even be that computers are the gateway to first contact.
The idea that we may be of no interest to an alien civilization until we hit some specific
technology is an old one.
Arthur C. Clarke’s short story The Sentinel is just such a story, which set the stage
for the much more extensive 2001 but in a very different form.
We have often thought of one possible indicator like this as the detonation of nuclear weapons.
When we did that, starting with the Trinity test blast of 1945, it has been suggested
that maybe we caught someone’s attention with it.
Another example from sci-fi was Star Trek First Contact, where due to the prime directive,
the Vulcans did not make contact until they saw a warp signature.
There it was only when a species became not just space faring, but had a method to rapidly
cross the vast distances of interstellar space were they of interest and had come of age
and safe to contact without damaging their civilization.
But there are other candidates for this gateway.
One I’ve mentioned before is generalized artificial intelligence, and that aliens remain
stealthy, yet function as a police force ready to intervene and stop civilizations from developing
this technology because it may prove a threat to the galaxy at large.
A sci-fi example here is the Geth from Mass Effect, had the Quarians been stopped from
developing that tech, they wouldn’t have gotten themselves into a pickle and no one
else in the galaxy would need to have shootout battles with their machines.
But there is another potential gatekeeper, that of Quantum Computers, a road we are now
actively going down.
One virtue of Quantum Computers, and a curse at the same time depending on your perspective,
is that they are the best codebreakers we will ever have.
They pose a very clear threat to any kind of encryption we now use should we be able
to bring them to their fullest extent.
It may be that to see an alien signal at all, and pick it out from the noise, you need a
quantum computer and that provides the aliens a method of stealth until they can be reasonably
certain we are technologically advanced enough to handle knowing about their presence.
But let’s take it from an alien perspective, and do a thought experiment along these lines.
Hypothetically speaking, say we caught a close radio signal from a planet, say from the alpha
centauri system, just under 5 light years away.
This would tell us two things, one is that there is someone there, and two that either
intelligent life in the universe is unbelievably common or there is a galaxy spanning civilization
at work in the Milky Way colonizing all suitable planets, or is in the process of doing so.
But if we have proof that someone is there, then what might we do?
This cannot be predicted.
On the one hand, we might do everything we can to go radio silent and try to cloak our
world with lasers to make it look like there’s no civilization here.
We do that, if you want to hide something, cover it in camo.
But we also do reconnaissance, and work is afoot to build a swarm of tiny light sails
driven by laser towards the Alpha Centauri system to explore it.
One merely needs time to wait for them to get there at some fraction of the speed of
light.
The concept is solid, we can take pictures and measurements from another star system
as long as we budget the time.
But if we saw a radio signal from that system, would that accelerate our development of such
efforts, would we have a greater motivation to do it since we know that we might be able
to glimpse and perhaps interact with aliens?
What would the aliens think of a swarm of reconnaissance micro spacecraft passing through
photographing their system like a foreign spy balloon over a superpower?
Where does bad first contact go from there?
It just goes to show, close aliens are not necessarily a good thing, whether the aliens
are us, or someone else.
Thanks for listening!
I am futurist and science fiction author John Michael Godier, currently concerned about
carnivorous plants having recently viewed some venus flytraps in the rare plant store,
yes I frequent one of those.
What if passive plant life in the universe isn’t the norm, and that the universe teems
with photosynthetic carnivores and aliens in the know serve as exterminators.
The moment the plants of an exoplanet appear to get out of hand, it’s curtains.
And since photosynthetic plants are one of the strongest biogsignatures out there …. Well,
let’s just say we’ve already been betrayed.
Plants are not our friend, but I’ve known that for a while due to interactions with
rose bush thorns and be sure to check out my books at your favorite online book retailer
and subscribe to my channels for regular, in-depth explorations into the interesting,
weird and unknown aspects of this amazing universe in which we live.