Remembering back, my first flirtation with science was geology.
As early as 1980 I was keenly aware that rocks were important, as my mother was a rock hound
and we’d travel the western US ostensibly for vacation, but really to rock hunt and
also to accompany my father who was a military contractor following where work led.
I very keenly became aware of geology on May 18, 1980 living near Portland Oregon and watching
Mt.
St. Helens erupt from a distance, a memory as vivid in my head today as it has ever been.
But that early experience with science led to one Christmas when I was somewhere around
11 years old when my parents bought me an inexpensive microscope and telescope set,
one of each, which were my constant companions for years after.
Indeed, I still have them.
That tiny telescope however, with only a 30 millimeter objective lens, allowed me to spot
something that ultimately resulted in this channel.
The rings of Saturn, which were visible even in such a tiny telescope, though much sharper
than Galileo saw them in 1610 as fuzzy lobes in his primitive refractor of only a few millimeters
larger than mine.
But visual astronomy is visual astronomy, the visible light spectrum.
Our ability to perceive and see this area of the spectrum is probably not something
we would widely share with alien life.
Indeed, we don’t entirely share it with the animal kingdom on earth.
For example, we tend to see color more vividly than some other mammals, perhaps some adaptation
for hunting and gathering, perhaps to spot colorful berries, and certain insects see
into the ultraviolet spectrum where we cannot, again probably something to do with the circumstances
of their existence.
Extending this to alien life casts an even wider net in that it’s difficult to envision
what senses they might have.
Eyes are useful, but not universal to life on earth.
Hearing is useful, but not so much on a world like Mars where sound has a much shorter range,
or that might also result in super hearing, or on an ocean world where sound would have
a much longer range.
But to detect rather than perceive is a completely different matter.
We don’t really perceive ultraviolet light until we get a sunburn because we don’t
see it directly.
But we know it exists and we can measure it, but humans from not that long ago had no idea
it was even there.
Radio even more so.
But with modern technology, we can basically detect the entire electromagnetic spectrum.
So technological aliens with science are going to know about the spectrum as well, and measure
it with instruments not unlike our own.
It’s an interesting thought that while aliens themselves may be radically different from
us biologically, we would probably recognize their radio telescopes and they would recognize
ours because nature offers only a few ways to build a radio telescope.
Nature dictates the ability to detect it, and you must play by nature’s rules.
Now intelligent aliens without technology and science would be essentially impossible
to detect, but those with advanced technology may stick out like a sore thumb.
We often look to radio for SETI, it’s ostensibly a straightforward technosignature to detect,
but there are others and of great interest are certain types of technosignatures that
may reveal what an alien civilization is doing as far as scientific exploration.
One of these potentially detectable scientific megastructures are gigantic telescopes.
First we have something that isn’t often mentioned, but it’s true.
Other than its biosphere, among the most detectable things this planet has ever emitted that aliens
might catch involves our scientific instruments.
Our broadcast radio or television is often held up as something aliens might detect,
but those signals are very very weak and it’s not likely past about a light-year that anyone
would even see it.
Unless they have a radio telescope the size of the city of New York, more on that in a
bit.
But what they might detect is our radar, but only if they are relatively close, both because
we’ve only been producing detectable radar since the mid-20th century, our signals have
not had time to reach out very far even at the speed of light, but also because of signal
strength.
So those sorts of science based technologies aren’t as detectable as you might think,
and one thing that would most certainly not be detectable is the infamous 1936 Olympics,
most famously brought up in the book and film Contact.
You’d have not detected that broadcast in Berlin without the right equipment, much less
in orbit and certainly not at cosmic distances.
A question I often get is how about the nuclear testing, would the detonation of a nuclear
bomb be detectable at a distance?
The answer is not really.
Certainly within earth orbit, very likely the moon, perhaps for a large part of the
solar system, but at interstellar distances not likely.
Oddly though, say there is a von Neumann probe sitting in the solar system monitoring us,
a double flash from a thermonuclear detonation would be distinct, and if you saw a series
of them, you could deduce that a nuclear war was occuring on earth.
A sad technosignature indeed, but I often wonder about a scenario somewhere out there
in the universe similar to the Vulcan’s detecting humans through the first warp drive
signature depicted in Star Trek just as they happened to be passing through.
Might a nuclear detonation get someone’s attention who happens to be watching our world
from within our solar system.
What might they do?
Might they make contact, or maintain a closer but subtle presence waiting to stop anything
that might get out of hand in the interest of altruism or preserving any occurrence of
intelligent life in the galaxy?
This also works for nuclear propulsion.
By dropping hydrogen bombs out of the back of your properly armored and blast plated
spacecraft, you would have one of the few ways we currently possess technologically
to reach some real fraction of the speed of light to get to other star systems faster
than chemical rockets could do it.
That too might be detectable, at least at close range.
But ultimately ambiguity once again rules the day here.
But there is one thing that once existed that in no uncertain terms told a large swath of
the galaxy that we are here and who and what instrument sent it, though it hasn’t had
time to propagate too far out in the galaxy.
No one in the path of this radio signal can miss it, if they are monitoring the skies
with all sky seti surveys all the time.
It was the Arecibo radio telescope.
It’s the famous Arecibo message that was broadcast by that radio telescope in 1974.
It was actually a half-hearted signal as far as contacting aliens however in that we never
repeated it, and it really was more for show that we could actually do it to commemorate
a renovation of the telescope, which decades later collapsed due to errors in the original
manufacturing that weren’t ever caught.
But if anyone ever detected this message, it’s possible that they might be able to
work out some details of the instrument that sent it.
The reason is simply that included in the message was a pictorial depiction of the telescope
itself, so if aliens can actually decode the message as a binary string, they will see
a representation of a human built radio telescope.
As an aside, there’s another way, though a long shot right now, where an alien civilization
could detect the specifics of our technology.
It’s another concept covered by star trek, this time in the first movie.
They could run across a piece of our space trash, such as a defunct voyager or pioneer
spacecraft drifting across interstellar space.
That’s so far beyond a needle in a haystack it will almost certainly never happen, but
if it did, it would represent aliens coming across a human scientific instrument, and
in the case of those spacecraft, bearing messages from earth.
So the point is, our science is among the most visible things we do as far as aliens
are concerned.
So assuming that aliens are the same way, what could we look for as far as technosignatures
that involve alien science experiments?
Well the first would be megastructure telescopes.
Here we deal with two basic types of telescope that are analogous in many ways to more familiar
megastructure concepts in speculative SETI.
This gets into the difference between Dyson Spheres and Dyson Swarms.
Freeman Dyson’s original idea was the swarm, which would be an orbiting cloud or constellation
of energy collectors designed to collect as much energy as possible from a star.
A Dyson Sphere, which should really be called a Stapledon Sphere as it predates Dyson, is
a completely solid encasement of a star to collect 100 percent of its energy.
And there are variants, such as a Niven ring, where it’s simply a solid ring around a
star potentially not only collecting some fraction of the star’s energy, but also
providing a living surface much greater than any one planet can provide.
As an aside, for those interested in Larry Niven’s concepts, see a link to an Event
Horizon interview where I discussed some of them with Larry along with his fellow science
fiction master Gregory Benford.
But here’s the kicker, any of these platforms can be used to host telescopes pointing away
from the host star, meaning such structures are dual use.
This is sometimes termed as a hypertelecope. Power your society with one side, and study
the universe with the other.
At least within limits, this may not be the best method for example for infrared astronomy.
We’re already flirting with a related idea, radio telescopes on the far side of the moon.
The idea there is that you can put a radio telescope on the far side of the moon and
do clean SETI searches because the bulk of the moon is blocking almost all earth interference.
Being on the outside of a Dyson structure should do the same, but provide a surface
area much larger than a planet in which to create an array of radio telescopes operating
as an interferometer.
This would yield a resolution far higher than anything you could do on the surface of a
planet, and in the case of a Dyson swarm, it’s already something we’ve begun in
the form of all of our defunct past spacecraft in solar orbit.
You could even apply this concept to the James Webb space telescope, while it peers out into
the cosmos opposite and insulated from the sun, while its sunlit side collects solar
energy for electrical power.
This scales up however.
If you’re working with interferometers, the laws of physics allow you to build telescopes
the size of a planet.
Or the size of a star system, since it’s made up of multiple units and not one single
massive dish or lens.
Or even the size of multiple star systems.
Yes, interstellar sized telescopes are in principle possible, if you’re willing to
allow for the time needed to transfer all of the data being collected.
But for a civilization that lasts for billions of years, even an interferometer the size
of their home galaxy is allowed by physics.
Difficult yes, but in this case difficulty is merely a function of time.
Interferometers can be optical or radio et cetera, or even multi-use; if you can station
an optical telescope array in another star system, you can station an infrared array
or a radio array as well.
This would offer an immense opportunity, you could study the universe at resolutions so
precise that you could spot continents on exoplanets, or even exoplanets in other galaxies.
In radio, you could hear signals from just about anywhere in the galaxy, even if they
are extremely weak.
There are a lot of reasons to build giant telescopes of this nature, thus it seems reasonable
to try to detect them as technosignatures.
This would likely be done through the transit method as the objects, if they are large enough,
pass in front of their host star.
Certain arrangements of these types of telescopes would probably not be visible, but if the
components are large enough you’d see them.
You might also detect in radio or laser the communications between the member units of
the array.
But those aren’t the only types of megatelescopes that might be detectable.
Another option would be to look for megatelescopes at certain points around a star.
The gravity of stars bend light, and thus can be used as gravitational lenses themselves
if you put a receiver at certain exact points in a star system.
Get a big enough megastructure receiver transiting and you might be able to not only spot it,
but due to its precise location you might be able to reasonably eliminate any potential
natural origins for the object you’ve spotted.
And if you have a number of them in the same orbit all using the same star as a gravitational
lens to look in different directions, it would be even more visible and unnatural looking.
And even stranger option would be if you turned an entire planet or exomoon into a telescope
array using liquid mercury telescopes.
You can’t use this technique in space, you need a gravitational body, but you can make
a comparatively inexpensive telescope this way.
Cover and entire moon or planet with these, and that in principle should potentially be
detectable as a technosignature, though to see that we’d need much more advanced instrumentation
than we currently have, probably on the level of a megatelescope.
But telescopes don’t have to have huge components, you could hypothetically create a nanotechnological
cloud telescope the size of a star system as well.
That would be difficult to detect however as it probably would be indistinguishable
from a dust cloud.
But there is one other type of mega instrument we might detect, and it’s very different
from a telescope.
It’s gigantic particle accelerators that advanced aliens might construct to get near
the highest energies possible in the universe to expand their knowledge of physics.
These would be the size of star systems, and produce characteristic ultra-high energy neutrinos.
Other than the big bang, it’s unlikely anything in nature could produce energies this high,
known as the planck energy, so if we ever saw these types of neutrinos we’d have to
ask if there is some high energy process in nature we’re unaware of, or if we’re seeing
the activities of alien physicists.
And if we did see that, it would teach us a science lesson by way of an alien civilization
that we still have a lot of work to do in achieving a complete understanding of physics.
Thanks for listening!
I am futurist and science fiction author John Michael Godier currently worried about the
neighbors.
So we build a giant megatelescope and point it at a nearby star system, only to see the
aliens construct another giant megatelescope pointing back at us.
And that’s first contact, very awkward 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.