This episode is sponsored by Audible. We often wonder where all the ancient alien
civilizations are, and if they might not exist. But could the reason be something as simple
as a vital element being scarce? So we had a big new discovery recently that
we found Phosphine gas on Venus, a possible biosignature for life, and while this episode
was written before that, and is focused principally on what the scarcity of Phosphorus might mean
for looking for alien life, it’s a bit too important and relevant of a discovery not
to address and so we’ll be getting to it at the end of the episode as an addition. Our regular viewers know that one of our favorite
topics, and indeed the topic that inspired me to start the channel in the first place,
is the Fermi Paradox. This is the great looming question in our
so-far fruitless search for other lifeforms in the galaxy. Why, when the universe is so vast and old,
and life can form spontaneously from base molecules and evolve into sentient beings
like we did, have we not detected any clear signs of life anywhere, let alone galactic
civilizations. The answer is that so far don’t know why,
but we have come up with a number of theories as to what might make it more rare and difficult
than we thought for life to form or for intelligence to arise, what forces might just occasionally
kill all life off and start the process over, and what errors in judgement might lead civilizations
to destroy themselves not very long after they start producing signals we could even
detect. And to be honest, I kind of hope that if life
really is as rare in the universe as we think it may be, the reason is something amazing
and dramatic like supernova storms or cognitive contagions, because then at least we are alone
out here because of something interesting. It is frustrating to think that the vast resource-rich
universe out there might be mostly empty and wasted and that we’re in it alone because
of some mundane quirk of chemistry. That is the troubling topic we will be discussing
today. The element phosphorus is essential to life
as we know it. But phosphorus appears to be rare in our solar
system, and more rare in the universe. There are good reasons to suspect that many
stellar systems, large swathes of our galaxy and others, where it may be very scarce or
at least lack enough of it for life to start. If this is true, the rarity of essential phosphorus
might be not only be the reason for the rarity of life, it might also put a hard limit on
how much life there can ever be—which would really put a crimp in our plans to populate
the galaxy with quadrillions of humans. Even if “Life finds a way” to arise and
evolve in stellar systems that lack phosphorus, that doesn’t change the fact that we, in
our current physical form, absolutely need it. And as we saw in our episode “Non-Carbon
Based Life”, the prospects for life not sharing our basic chemistry are not very good. So, let’s take a moment to understand why
phosphorus is essential to life as we know it. We describe the lifeforms of Earth as carbon-based
because so many molecules essential to organic metabolic processes are built around branching
chains or loops of carbon atoms. But phosphorus is so ubiquitous in essential
organic compounds, it would not be unreasonable to refer to Earth-like lifeforms as carbon-phosphorus-based
life. If you ask most science writers why phosphorus
is essential, they’ll tell you immediately about Adenosine Tri-Phosphate, ATP, the chemical
that all known lifeforms on Earth use to transfer energy. When plants absorb sunlight and produce oxygen
in photosynthesis, that oxygen is actually just a byproduct of the first step of photosynthesis. The end result of the last step of photosynthesis
is converting ADP, Adenosine Di-Phosphate into higher energy ATP. Pushing the third phosphate group onto the
adenosine is somewhat like compressing a spring, storing energy that can be released later
and where it’s needed. When enzymes within cells convert the ATP
back into ADP, that huge energy release is what powers the enzyme and the basic functions
of the cell. Multicellular lifeforms, ourselves included,
who don’t do photosynthesis but instead just breathe oxygen to burn sugars to power
a different process that also converts ADP into ATP and then uses the ATP to power enzymatic
cellular processes in pretty much the same ways plants do. So every known lifeform on Earth—except
a few that are just big molecules that strain our definition of the term lifeform—are
powered by a cycle of pushing phosphate groups like springs down into ADP and using that
stored energy that’s released when they pop back off. But an even better illustration of why phosphorus
is essential to Earth-based life is right there in the structure of DNA and its simpler
ancestor RNA. Every other link in that vastly long molecular
chain is a phosphate group with a phosphorus at the center. So without phosphorus, we lose the very means
by which all known life encodes the instructions for becoming alive, remaining alive, and making
more stuff that’s alive. Of course you could point to any atom in RNA
or DNA—the carbon, nitrogen, oxygen, or hydrogen—and declare that without it life
as we know it couldn’t exist. And you would be correct, but all of those
elements are quite abundant throughout the universe. We are only a little over 1% Phosphorus by
mass, but it is even rarer on Earth, making up about 0.1% of the crust and not even in
the top ten most common elements here. It’s even rarer than that in our Solar System,
coming in at seventeenth place for abundance, making up a paltry 0.0007% of the mass of
the solar system. We aren’t sure how common it is Universe-wide
and there’s some debate if it’s more abundant in our solar system or not, but planets and
stars older than Earth would tend to have lower concentrations as fewer supernovae would
have occurred in the distant past to add heavy elements to the galaxy at large. And for the Fermi Paradox, a critical concept
is why we don’t see older civilizations around and perhaps it is from Phosphorus scarcity
preventing life from emerging in the first place. Earth’s amount and the general reactivity
issues of phosphorus already are low enough that for decades the “Phosphate Problem”
has stumped scientists trying to figure out the origin of life on Earth, and we’ll discuss
that in a bit, if you go to some planet with an even lower concentration of Phosphorus
that problem would only be worse. The most ten common elements in the Universe,
in descending order, are hydrogen, helium, oxygen, carbon, neon, iron, nitrogen, silicon,
magnesium, and sulfur. Only 1 in 2000 atoms are not one of those
ten, and Phosphorus only makes up 3 out of every ten million atoms. Silicon atoms are 100 times more common. So why is phosphorus so much less abundant
than the other elements essential to life? To answer, it helps to look at how and where
the various elements are produced. It’s a common misconception that most heavier
elements are produced in supernovae, but this is not correct. Almost all elements with more than 40 protons
in them – like gold, platinum, or uranium – come from the collision of neutron stars. In contrast, the lighter elements mostly come
from the death pangs of smaller stars, the final stages of fusion. For example, silicon is the last element for
fusion fuel and one that only the most massive stars only burn for about a day before they
explode. Big stars are very inefficient users of fusion
fuel and burn in layers, so when they detonate plenty of unfused fuel of various types gets
scattered. Many of the elements said to come from Supernovae
are actually produced in this way, as fusion products in the star’s old age, and just
get scattered when it explodes. And not all supernovae are Type II, giant
exploding stars. The other common variety, Type 1a, are white
dwarfs stellar remnants that explode after pulling mass off some close binary partner. But phosphorus seems to mostly be produced
in Type II supernovae, and only during the supernova event itself. The most likely mechanism is when the Silicon-30
isotope captures a neutron during the explosion, briefly becomes unstable Silicon-31, then
quickly emits an electron and decays into phosphorus-31. But silicon-30 is not the most common silicon
isotope, and its capture cross-section for neutrons is very small, meaning the neutron
has to hit just right to get absorbed, so it doesn’t happen very often. We also know that Type II supernovae are not
distributed evenly in the galaxy, and supernova remnants appear to have significantly varying
concentrations of phosphorus. Shockwaves from supernovae carry matter into
space and are thought to be what compresses the interstellar material and triggers it
to begin coalescing into proto-stellar systems. If phosphorus were lower in concentration
in those shockwaves, then those new star systems and their planets will also have less phosphorus
than other systems like our own. So the problem isn’t just that phosphorus
is rare, it might also be unevenly distributed, with huge swathes of our galaxy almost lacking
it. And the mere existence of phosphorus in a
stellar system doesn’t necessarily mean it’s available to facilitate the formation
of life. The abundance of elements in the crust of
our planet doesn’t match up too well with the solar system at large, even ignoring the
hydrogen and helium differences as they’re super-abundant but only in places like the
Sun and Gas Giants that can hold onto the ultra-light particles. Our crust is not our planet and some materials
sank in toward the core when the place was molten. Especially those prone to forming up big dense
molecules, while Silicon for instance tends to float on magma well and stay near the surface,
and thus is right behind oxygen in it’s crustal abundance even though carbon, nitrogen,
and neon are more common in the solar system. Earth has a lot of phosphid[a]e, relatively
speaking, but most of it is down in the planetary core. What’s more, phosphide isn’t very useful
for life, unlike phosphate, which is phosphorus linked up to oxygen atoms… which might be
a bit problematic on Earth for the purpose of life forming since there was not an oxygen
atmosphere on this planet until long after life had formed. But Phosphorus also tends to bind into molecules
that are insoluble in water, which is very problematic for life, since it is pretty much
predicated on water-solubility. Indeed of all the biogeochemical cycles for
life, many of which are quite quick and often involve the atmosphere, the phosphorus cycle
does not involve the atmosphere and has one of the slowest cycles. It slowly grows rarer on land as it washes
out to sea and sinks, and only gets refreshed by tectonic activity. If you have some hypothetical chemical solution
from which the first building blocks of life needed to arise, then we have an issue with
there being virtually no phosphorus around in that solution. If the stuff is rare, in forms that aren’t
water soluble, and prone to sinking, then you’ve got a bit of a problem. Just to take a simplified example, we said
there were six key elements for life, Oxygen, Carbon, Hydrogen, Nitrogen, Calcium, and Phosphorus
in that order, and that is same number as there are sides on a dice. Let’s say we were rolling a bunch of dice,
10 of them. The odds of any specific combination getting
rolled is 1 in 6^10, about 1 in 60 million. On fair dice anyway. So our odds of rolling 10 6’s are pretty
low. Now if our dice are badly balanced so that
instead of a six coming up 1 in 6 times, 17% of the time, it only came up 1% of the time,
or 1 in 100, then the odds of rolling 10 6’s isn’t 1 in 6^10 but rather 1 in 100^10,
not 1 in 60 million but rather 1 in 100 billion-billion. For perspective, if we had some solution that
was forming molecules once a second on that 1 in 60 million odds, and dropped the concentration
so it was now 1 in 100 billion-billion, that formation reaction goes from once a second
to once every 50,000 years. And if we dropped the odds from 1% even more,
down to .1%, that would now happen on average once every 500 trillion years, 40,000 times
longer than the Age of the Universe. That gives you an idea how important having
the right concentration of Phosphorus in the primordial soup of life is. Even just halving the chance of rolling a
six in our previous example would have lowered the odds a thousandfold, requiring either
a thousand times as much of the solution or a thousand times as long, so even a relatively
minor variation in the abundance of phosphorus in a planet’s crust is a big deal. Using our 10-dice example, a thousand planets
with half the concentration would have the same odds of generating life on just one of
them as one planet with double the concentration has, and for the ones with a tenth the concentration,
you’d need 10 billion of those planets to equal the odds that one lone planet had. As you can see, even an entire galaxy of planets
doesn’t need much of a drop in availability of phosphorus to be very unlikely to have
a single planet have life form on it. And as I mentioned earlier, Earth has unusually
high concentrations of Phosphorus in the crust, but they’re still troublingly low for models
of life forming here. So how did we get a high enough Phosphorus
concentration here on Earth? Well, we generally assume life formed in one
of 3 ways, in tidal pools, or around deep sea thermal vents, or with it originating
in space and coming in on a comet or meteorite – a concept called Panspermia, see that
episode for details. And indeed we suspect that a lot of the phosphorus
available to early life came in by meteorites after the planet formed. For life to originate near geothermal vents
or tidal pools, the problem is the phosphorus concentration. Phosphorus in seawater nowadays is 0.1 parts
per million, quite low and not really very conducive to life, but we see it higher near
thermal vents, if not really high enough, and tidal pools tend accumulate runoff, get
stirred up and muddy, and evaporate to higher concentrations, so either is an okay-ish candidate,
in the absence of something better, but still don’t exhibit anything like the concentration
of phosphates that would make the odds good and we always assume life started in or near
an ocean given that life was around for billions of years in the ocean before land life emerged. And this is the “Phosphate Problem” I
mentioned near the beginning. There just doesn’t seem to be any good options
for anything in the sea to have had a decent concentration of phosphates to make a primordial
soup which life could emerge in. However, recently it’s been suggested that
carbonate rich lakes, those in dry environments where runoff water flows in but evaporation
keeps them salty and alkaline might be a better candidate. While they vary in concentration a lot, we
have found some of these carbonate-rich soda lakes with 50,000 times the phosphorus levels
of seawater. Such lakes might have been a good deal more
common in the past too, given that a Primordial Earth with no plants and roots holding the
soil in place would have a lot of runoff and erosion. Those lakes being carbonate-rich helps too. Normally if you have a lot of calcium present,
and there’s more of it than phosphorus, it will bind with phosphorus into calcium-phosphate
which life can’t access, but carbonate can bond to the calcium as calcium carbonate and
leave some phosphorus free. Primordial Earth is thought to have had an
atmosphere principally of nitrogen and carbon dioxide, and also far more volcanic activity,
which may have allowed even higher concentrations of phosphorus than these modern lakes we’ve
investigated. Phosphate levels might have been able to climb
in some cases to a million times the concentration in seawater, potentially 1 in 10 atoms rather
than 1 in 10 million, vastly higher than any suggested in normal tidal pools or deep sea
thermal vents. So, okay, maybe phosphorus is rare, and biologically
accessible phosphorus even rarer, and key biological processes require phosphorus. But didn’t Ian Malcolm from Jurassic Park
teach us that “Life finds a way”? Surely, life and evolution being as inventive
as they are could concoct some alternative molecular mechanism for energy transfer that
doesn’t involve phosphorus, right? Well, that’s why I keep using the phrase,
“Life as we know it”. Of course we can’t know for sure if life
needs to run on water and carbon and phosphorus like it does here and in the same way it does
here. We took an in-depth look at that in our episode
Non-Carbon Based Life and covered a ton of options from alternative chemistries to crystal
or metal deposits forming into big natural computers. In our episode Void Ecology we contemplated
how complex life might arise in space rather than planets with atmosphere and oceans, and
we even contemplated wilder scenarios like life emerging inside stars in our episode
“Conscious Stellar Objects” However, the very fact that life on Earth
evolved to make such ubiquitous use of phosphorus when phosphorus is not all that common tells
us one of two things, possibly both. Life based on phosphorus was easier to form
than a non-phosphorus mechanism, and/or life based on phosphorus was far more successful
once it did form. And that strongly implies that whatever life
could form in a primordial ooze lacking phosphorus won’t form easily and/or might not be nearly
as adaptable or successful. If you’ve got a creature on an alien planet
than can eat iron ore and another that can only eat gold nuggets, all things being equal
that iron-eater is going to be wildly more successful, so if you find a world dominated
by gold eaters but plentiful in iron ore, it tells you iron-eating life is either wildly
improbable to develop or that gold-eating life is way more likely to prosper. Same concept for phosphorus, if life had been
able to develop using something less scarce, Occam’s Razor says it would have. So this is a very plausible solution to the
Fermi Paradox. We might very well be alone because we are
on a very rare planet that has enough of a rare element that life doesn’t form easily
or work well without. And the rest of the universe is just out of
luck. Or alternatively, such planets are pretty
rare and were even rarer in the Earlier periods of the Universe, which is almost as good for
the Fermi Paradox, because as we saw in the Great Filters series, there’s plenty of
other things that can lower the odds of life forming too, and lower the odds further of
it getting intelligent and building spaceships. Remember, the Fermi Paradox isn’t about
if other civilizations exist equal to modern day humanity, but rather if older ones exist
who could have gone out and colonized the galaxy and be noticeable to us with our current
technology. So if worlds older than Earth tended to be
scarcer in Phosphorus, you might have more worlds with life but just not that developed
yet. We might just be the first to be building
spaceships, as we looked at recently in our episode Fermi Paradox: Firstborn. Time is a factor too. Keep in mind I gave concentrations of Phosphorus
in the modern Universe, not what it was 4 or 5 billion years ago when our young planet
got it’s allotment. The Universal average would have been much
lower at that time than now because there hadn’t been as many stars that became Type
II supernovae. The younger a planet or solar system is, the
older the universe was when it formed, and the better its odds of having higher concentrations
of Phosphorus. So there’s an optimistic angle on this story;
as the Universe gets older, it might be becoming more fertile for life to form. But the most annoying part of the Phosphorus
Problem for futurists is that, since we humans require phosphorus, we might not be able to
just rush out and populate that vast universe full of resources awaiting us, because how
much phosphorus we find or make sets a hard limit on how many of us there can ever be. Humans and our food are mostly made of water,
which by mass is mostly made of oxygen, but we’re also about 1% phosphorus. So let’s say we send a colony ship to a
stellar system abundant in every imaginable resource except it’s sorely lacking in phosphorus
that’s reasonably easy to get to. But say we send those colonists off with a
generous stock of a million metric tonnes of phosphorus from Earth, a billion kilograms. And let us say that they don’t waste any
precious phosphorus on pleasant grasslands or forests or pets, and they strictly recycle
every precious atom of it. And let’s further assume that every human
has a mass of about 70kg and that at any given moment there’s another 30kg of feedstock
on hand, which makes a nice round number of 100kg of biomass and hence 1kg of phosphorus
required per human. That means that the billion kilograms of phosphorus
they brought will build one billion humans and their food, and that’s it. Perhaps you could double that by making people
smaller and keeping less food in reserve, but clearly there’s a hard limit where they
can’t make any more food or babies until they find some more phosphorus. And that’s assuming there are nothing but
humans, when in practice, our planet has about 3 trillion tons of life on it, 18% of that
is carbon and we often give biomass in tons of carbon, and 1% is Phosphorus, or 3 billion
tons. That means for terraforming and colonizing
a world to our current population and ecology, you’d have about 400 kilograms of Phosphorus
per person, not one kilogram, only including the Phosphorus tied up at any given moment
in something alive, and if you’re terraforming planets or building big space habitats, you’re
going to need values like that. Again you might lower that by having a higher
percentage of biomass be people, or it might be lower if you like garden parks and rural
space habitats and planets, and of course you need a lot sitting in soil not just lifeforms. Let us ballpark it at one ton per person for
simplicity’s sake. Earth is the most massive rocky planet in
the solar system and indeed masses around as much as all the other rocky planets, moons,
and asteroids combined do. However only about 1% of its mass is in the
crust and only about .1% of that is Phosphorus, so if we extracted every last bit of it from
our crust we would have about 10 million-billion tons, enough for 10 million-billion people,
a million times our current population. And that is only Earth and only Earth’s
crust, it might have a high abundance but there is more phosphorus in the solar system. Now we often talk about how a Dyson Swarm
is the likely fate of solar systems where technological life develops or visits – A
Dyson Swarm or Dyson Sphere being a collection of objects around a star using up all it’s
available energy. Since the Sun gives of 2 billion times more
light than reaches Earth, we generally just multiply our population by 2 billion to guess
as Dyson Swarm populations, and that would be 16 billion-billion people, 1600 times the
10 million-billion figure for a ton of phosphorus per person and still a bit larger than the
one kilogram of phosphorus per person we could have if humans were the only life period. For Dyson swarms, we don’t assume that collection
of objects orbiting the sun and using all its light would all be space habitats, but
we’re often worried about finding enough mass for all those and one solution to come
up with the raw material is to engage in starlifting, as stars form from the same stuff as the planets
around them so are heavy in metals, just way heavier in hydrogen and helium. And indeed most of the Phosphorus in our solar
system is in our Sun, it doesn’t make Phosphorus, mind you, and never will, but again it formed
from the same nebula Earth did. If you sucked all the Phosphorus out of our
Sun, which is presumably where 99.8% of our solar system’s stockpile is since it is
99.8% of the solar system’s mass, then you would have a lot more. Our Solar system masses 2 billion-billion-billion
tons. Again though, Phosphorus is less common off
Earth, making up only 7 parts per million of the mass or 14 billion-trillion tons. So that’s your hard limit, if you suck out
every drop from the Sun, excluding the Sun it drops a lot, and leaving in the Gas Giants,
which have most of the remainder, leaves you 28 billion-billion tons. So there is enough for space habitats, barely,
but it turns out to be a major control factor on building them if you want life on them. And this is only if you’re dismantling solar
systems, not if you’re just mining asteroids, and we can’t assume at the moment that phosphorus
will be decently abundant in other solar systems, especially on the crust of big planets, so
folks going out and colonizing distant planets around other stars are going to need to find
some phosphorus. Or make some. We never want to limit ourselves to assuming
natural sources when dealing with advanced civilizations. After all we’ve barely reached our own Moon
but we already make elements that don’t occur naturally in the Universe. So a civilization might avoid a Phosphorus
bottleneck by just getting it out of stars – not simply by starlifitng, but by using
the star’s power supply to run a ton of supercolliders or atom smashers to make some. Silicon-30 is fairly common, the heaviest
of the 3 stable silicon isotopes and about 3.1% of natural silicon, you whack that with
a neutron at a speed that captures it and you’ve got silicon-31, with a half-life
of a couple hours before it decays into regular old stable phosphorus. As we mentioned last week in the Future of
Fission, we do this type of transmutation in labs all the time via breeder reactors,
it’s how we make plutonium. Transmutation is rather expensive, but if
phosphorus turns out to be a bottleneck for the growth of our civilization, I’m sure
we’ll develop the means to get a lot better at it. But even if we do develop such industrial
processes for mass-synthesizing phosphorus, synthesizing just about anything is a lot
more expensive than simply finding it. Any native deposits of phosphorus will be
prized, mined quickly and maybe even become a critical commodity folks have wars over,
perhaps even more prized than the precious metals in the asteroids since, literally,
we can live without precious metals. There might be life out there somewhere that
eats gold, but we don’t, we need phosphorus, and the odds are high that life out there
does too. So as I mentioned at the beginning, we had
a big piece of news come in while we were working on this episode, the discovery of
clouds of Phosphine gas on Venus, and I didn’t think we could run this episode without giving
that a mention. The phosphine molecule consists of one phosphorus
atom bonded to three hydrogen atoms, forming a trigonal pyramid. It’s highly flammable in oxygen and highly
toxic to life on Earth. In fact, it’s a substance we normally only
encounter on earth in life that’s falling over dead. It’s literally rat poison, so phosphine
gas actually kills things, at least things that breathe oxygen. Importantly, though, it is only poisonous
to aerobic, oxygen-breathing organisms. Anaerobic life is a completely different consideration. On Earth, it’s produced by some anaerobic
microbes in water low in Oxygen as anaerobic life depends on low Oxygen levels. Venus has very little molecular oxygen in
its atmosphere, so any airborne organisms there would be anaerobic and might emit phosphine
like their Earthly cousins. To understand the excitement around discovering
phosphine in Venus’ atmosphere, we need to talk about atmospheric biosignatures. We usually mean by this that a given molecule
either shouldn’t exist in the atmosphere or should be far lower in concentration without
some biological process in place to replenish it. High concentration of molecular oxygen is
the big one, because we know of photosynthesis and not many other processes that produce
it, and because it’s so reactive that plenty of processes would consume it all if it wasn’t
being replenished by life. Something similar might apply to phosphine
gas. As I said, some anaerobic Earth microbes do
produce the stuff, and it breaks down very quickly in our oxygen-rich atmosphere. Earth microbes produce it from environmental
phosphorus or indirectly by fermentation of organic matter to get energy. It also acts as a defense mechanism for them,
both to poison oxygen-breathing competitor microbes and to remove deadly oxygen from
the water around them. So if you find any concentration of it on
a planet with an oxygen atmosphere, it would be a strong biosignature. But it’s not such a definite life sign in
Venus’s atmosphere, which has abundant clouds of acid to react with any metal phosphides
present to release phosphine, and where the phosphine would be broken down reacting with
other gases that break it down more slowly than oxygen does. So the phosphine could be being created and
replenished by life on Venus, but the evidence isn’t strong. It’s really just a could-be. We also shouldn’t discount the differences
in chemistry between Earth and Venus. Venus has some truly hellish environments,
both on the planet’s surface and in its thick atmosphere and I’m not only talking
about high temperatures and pressures, but also the highly acidic and chemically reactive
environments too. Phosphine is a very simple chemical and we
know that even comparatively more complex amino acids that we have detected in comets
and asteroids appear to be a purely chemical byproduct without the need for life to produce
them. We are far from fully understanding the very
different chemical melting pot that is Venus and the phosphine could simply be a product
of that chemical stew. As to Phosphorus scarcity, Venus certainly
has a decent amount of Phosphorus but don’t take this as an indicator it represents a
great stockpile, the amount of Phosphine found in the atmosphere is quite small compared
to what we might expect for a biosignature. The shock of this discovery was mostly just
that we found any phosphine gas at all. Still, it can’t be ruled out that there
might be life in the clouds of Venus, and strange life at that. That is all the more reason to get ourselves
out there for a closer look, and we contemplated some ways for doing just that in our episode
Colonizing Venus. We’ll get to the upcoming schedule in a
moment. But first, if you enjoyed this episode, you
can thank Jerry Guern, one of our regular editors on the show who pitched the idea to
me. He also co-wrote this episode and quite a
few others. Jerry’s is also a sci-fi / fantasy author,
and last year I encouraged him to start his own YouTube channel for his short stories. He now has several posted on his channel,
Jerry’s Stories, that I’ve really enjoyed. The most recent is a philosophical time travel
story called Paleontology. I helped review this one while he was drafting
it, and I instantly loved it. If you like time travel, dry humor, and very
good writing, check out Paleontology at the link in the Description. That’s actually a piece of advice I give
a lot of authors who ask for suggestions, narrate your own short story or some samples
chapters and put it out there for folks to listen to, either on youtube like Jerry Guern
did or even on Audible, folks are often surprised how simple it is to publish your work there. As I often say, a good narrator makes a good
book even better, and some of my favorites have been the audiobooks narrated by the author,
some of my favorite self-narrated audiobooks include the works of Douglas Adams, Niel Gaiman,
and Roger Zelazny. Speaking of Douglas Adams, while he’s best
known for the Hitchhiker’s Guide to the Galaxy, another of my favorites by him is
Dirk Gently’s Holistic Detective Agency, our Audible Audiobook of the Month. The novel offers its own interesting discussion
of how life arose on Earth, inspired by some of his time as a script writer for Doctor
Who during Tom Baker’s amazing run, and unsurprisingly it also features time travel. It’s one of my personal favorites, and Adams
narrates as well as he writes, though there are other versions with different narrators
and even a full cast audio drama version, and they are all available on Audible. You can find that audiobook, along with the
rest of Douglas Adams’ legendary work, over at Audible. They also have podcasts, guided-wellness programs,
theatrical performances, and exclusive audible originals, indeed they have over three centuries
worth of audio if you just hit the play button and ran it through every title. If you want access to that massive collection
of great audiobooks, like “Dirk Gently’s Holistic Detective Agency”, you can join
Audible for a 30-day free trial, and Audible members not only get discounts on any audiobooks
they buy, but a free book every month. Additionally, they are now giving unlimited
access to their audible originals. You can start listening today with a 30-day
Audible free trial. Just visit the link in the episode description,
Audible.com/Isaac, or text “Isaac” to 500-500. So this wraps our episodes up for September,
but we still have our Monthly Livestream Q&A coming up this Sunday, September 27, at 4
pm Eastern Time, and as usual we’ll be taking questions from the audience in the livestream
chat as we go. Then we’ll start October off with the Third
episode of our new series, Becoming an Interplanetary Species, as we return to the Moon, and stay
there this time. Then the week after that we’ll be taking
a look at Mega-Cities, the popular concept in science fiction, and we’ll see what sort
of challenges and surprises await us in the future if our cities keep growing. If you want alerts when those and other episodes
come out, make sure to subscribe to the channel, and if you’d like to help support future
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Our agricultural system works by mining phosphorous, dumping lots of it on fields and then transporting it to the consumer who then eats it and then ends up in the ocean. Peak Phosphorous is a real problem facing humanity and unlike peak oil there are no renewable alternatives to phosphorous.
So all those alien invasion movies where they come for our water should have edited their scrips so that they come for our phosphorus.
Could someone explain to me the part about probabilities (starting at 10:00)?
Why would a planet with half the concentration of Phosphorous have only 1/1000th the chance for life to form?
That doesn't seem right to me.