Knowing and articulating just where you are is the most important part of navigation,
without it you’re lost.
We solve this problem in the modern world with the various GPS networks we now use.
But despite the technology of the past, such as compasses, not knowing exactly where you
are has been disastrous in history.
In 1707 a naval disaster befell the British Royal Navy who lost several capital ships
due to the fact that it was extremely difficult for navigators to correctly calculate longitude.
In short, they weren’t where they thought they were and crashed into rocks during bad
weather.
This led to the development of the marine chronometer, pioneered by John Harrison.
This is a problem for space too, though on galactic scales rather than the scale of an
ocean.
In 1972, Carl Sagan, Frank Drake and Linda Sagan were faced with just such a problem
when devising the pioneer plaques.
How do you tell an alien civilization where you are?
Setting aside the merits of giving aliens a road map to earth, they used the relative
positions of 14 pulsars in relation to the center of the galaxy.
This makes sense.
It’s a good bet that a space faring alien civilization would understand the principles
of navigation, and also understand how uniquely odd pulsars are and how useful they are for
determining where you are.
Pulsars can be like clocks.
Specifically, millisecond pulsars emitting x-rays are particularly good and have an accuracy
comparable to an atomic clock.
In fact, the accuracy of some pulsars in their emissions are so regular and accurate that
they don’t, on their face, seem natural.
Because of this when they were first discovered, pulsars were initially thought to be of human
origin, they looked so artificial.
They looked like some type of interference.
But then it was shown that they weren’t and they were distant.
Then aliens were seriously considered.
We know now that isn’t the case either, or do we.
In a 2017 paper by Clement Vidal, link in the description below, the question of the
origin of pulsars has been reopened, at least for a certain type.
Vidal details that pulsars were eliminated as being of potential alien origin for five
reasons.
The first was because of the truly huge amount of energy a pulsar radiates.
But Vidal shoots this down by pointing out that we really have no idea what the energy
usage of an advanced alien civilization would be.
After all, we do talk about Kardashev scales and building dyson spheres, all of which imply
high energy use.
We also don’t know what the rules are there.
If pulsars aren’t natural outright, it would take a lot to create one.
But if they are partially natural but their output is being tweaked by a civilization
for navigation use, energy and resource expenditure equations change.
The second contributing argument to ETI being ruled out with pulsars was that they are not
unique.
The argument was made years ago that it would be unlikely for two separate alien civilizations
to be broadcasting at similar frequencies towards earth at the same time.
Vidal shoots this down too, noting that aliens coming to earth and seeing two cellphones
broadcasting on the same frequency would be silly to conclude that it was natural.
He goes further and points out that nothing says the pulsars are meant as messages to
us, rather they could be navigational beacons.
The third argument was that the signals from pulsars did not emanate from a planet.
Vidal points out that there is a bias here, and he’s right again, that an artificial
extraterrestrial signal does not necessarily need to come from a planet, or even anywhere
close to a star system.
It’s probably more likely that it would, but in the end we really don’t know where
they might come from.
The fourth argument is that pulsars are not narrowband.
Not by a long shot, actually.
SETI tends to favor narrowband signals as candidates for a detection because it doesn’t
really make sense, or didn’t used to make sense, to beam out a communication signal
broadband because you’d waste a lot of energy for no reason.
Vidal counters that we ourselves emit in a broadband way, and if the pulsar were natural
with one area of the spectrum was being tweaked for communications, the rest of the emissions
could just be the remaining natural transmissions of the pulsar.
Fair enough.
The final one, number 5, is the strongest and this is where I get skeptical.
Fully natural models for pulsars exist, in fact we have a fairly good understanding of
them and how they form.
In other words, an alien origin explanation simply isn’t needed when you have natural
models that fit the bill.
Vidal counters this with three answers.
The first is that to consider pulsar formation as an effect of an extraterrestrial intelligence,
you don’t need to throw those models out.
They could be fully natural and simply are being manipulated by the ETI, specifically
millisecond pulsars, or could be present in nature, but could also be created by artificially
triggering a supernova.
The second is that there isn’t a unified model that explains all pulsars, they are
a wide field with lots of variations.
Lastly, Vidal notes that it’s conspicuous that some pulsars pulse so accurately as to
be on level with atomic clocks, and that they are distributed well enough to be used in
navigation.
That looks a little odd to be sure, but the author also notes, rightly, that not all pulsars
are suitable for navigation, mainly only the millisecond ones.
This was an interesting paper, and serves to show the usefulness of reexamining old
ideas.
I’m skeptical on this one, given the weight of pulsar research, but it does open up a
new possibility for SETI and should be looked at.
But what I found most interesting is that even if all pulsars are fully natural, they
may well be the one thing in our galaxy that all spacefaring civilizations present are
using for navigation.
We’re looking at them too, and used them on the Pioneer plaques, so in a sense we may
already be a user of the galactic positioning system without realizing it.
Thanks for listening!
I am futurist and science fiction author John Michael Godier currently advocating the addition
of taking naps to the summer Olympics roster, I’ll win the gold every time though it won’t
make for good television ratings and be sure to check out my books at your favorite online
book retailer and subscribe to my channel for regular, in-depth explorations into the
interest, weird and unknown aspects of this amazing universe in which we live.