Speaker 1: Welcome to Bedtime Astronomy. Explore the wonders of the cosmos
Speaker 1: with our soothing Bedtime Astronomie podcast. Each episode offers a
Speaker 1: gentle journey through the stars, planets, and beyond, perfect for
Speaker 1: unwinding after a long day. Let's travel through the mysteries
Speaker 1: of the universe as you drift off into a peaceful
Speaker 1: slumber under the night sky.
Speaker 2: Picture the most alien inhospitable environments you can possibly imagine. Like,
Speaker 2: I want you to close your eyes and really try
Speaker 2: to visualize this.
Speaker 3: Oh, this is a fun exercise. Go ahead.
Speaker 2: Okay, So you're standing on a shoreline, right, But the
Speaker 2: liquid that's lapping at your boots it isn't water. It's
Speaker 2: a vast lake of liquid methane.
Speaker 3: Right.
Speaker 2: It's hundreds of degrees below freezing, and it's sitting under
Speaker 2: this thick, hazy orange sky that completely blocks out the
Speaker 2: sun sound. Or maybe you're suspended in this massive turbulent
Speaker 2: cloud layer. You're being whipped around by hurricane force wins
Speaker 2: and the mists that's collecting on your suit it's pure
Speaker 2: concentrated sulfuric acid.
Speaker 3: Wow. Okay, yeah, that's hustle.
Speaker 2: Right, Or perhaps you are plunging into the pitch black,
Speaker 2: crushing depths of an ocean, locked beneath miles of solid ice,
Speaker 2: and literally the only source of heat is the faint
Speaker 2: radioactive glow from the planet's core.
Speaker 4: Those are some incredibly bleak scenarios, they are.
Speaker 2: But here is the massive question for you. What if
Speaker 2: I told you that these aren't dead zones? What if
Speaker 2: these terrifying, totally extreme landscapes are actually thriving ecosystems.
Speaker 4: I mean, it requires a profound shift in perspective. Yes,
Speaker 4: it fundamentally challenges how we even define life.
Speaker 2: Because right now, literally everything humanity understands about biology is
Speaker 2: built on what we know works exactly.
Speaker 4: Every textbook you've ever read, every planetary probe we've ever launched,
Speaker 4: all our theoretical models for habitable worlds, they're all built
Speaker 4: on two completely unshakable.
Speaker 2: Pillars, liquid water and oxygen.
Speaker 4: Liquid water and oxygen, that is the old standard.
Speaker 2: We are entirely obsessed with them. And you know, you
Speaker 2: have to wonder, are we suffering from this massive cosmic
Speaker 2: case of earth centric bias.
Speaker 3: It's a very valid question.
Speaker 2: Because the universe is just unimaginably vast and chemically it
Speaker 2: is wildly diverse. So today our mission is to embark
Speaker 2: on this totally mind bending exploration into alternative biochemistries.
Speaker 4: We are basically going to deconstruct the rules of life
Speaker 4: as we know them.
Speaker 2: Yeah, we'll examine exotic solvents like ammonia and sulfuric acid,
Speaker 2: will question the absolute necessity of oxygen, and we'll see
Speaker 2: how throwing out the biological rule book completely rewrites our
Speaker 2: hunt for extraterrestrial life.
Speaker 4: Because, I mean, the laws of physics and chemistry are universal.
Speaker 4: A carbon atom behaves the exact same way here on
Speaker 4: Earth as it does in the Andromeda galaxy.
Speaker 2: Right, the fundamental building blocks are the same everywhere exactly right.
Speaker 4: But biology, biology is an emergent property. It's this highly
Speaker 4: localized phenomenon that adapts to its specific environment. So to
Speaker 4: just assume that biology must always look like Earth biology, well,
Speaker 4: it's arguably a bit of a failure of imagination.
Speaker 2: So let's unpack this Goldilocks bias we have. Let's start
Speaker 2: with the big one, which is water. We constantly hear
Speaker 2: it called the universal.
Speaker 3: Solvent, right, the magic liquid?
Speaker 2: Yeah, and it dictates literally everywhere we point our telescopes.
Speaker 2: But what makes it so biologically magical that astrobiologists refuse
Speaker 2: to really look for anything else.
Speaker 4: Well, water truly is a chemical marvel. Like there are
Speaker 4: highly practical structural reasons why we prioritize it so heavily.
Speaker 2: It's not just because it's what we drink.
Speaker 4: No, not at all. First and foremost, you have to
Speaker 4: remember that life is at its core this continuous, highly
Speaker 4: choreographed series of chemical reactions. And for those reactions to happen,
Speaker 4: you absolutely need a liquid medium. You need a place
Speaker 4: where molecules can float around freely, interact and transport materials.
Speaker 2: Because if things are solid, they're just they're locked in place,
Speaker 2: they can't do anything right.
Speaker 4: And if they are a gas, they're way too diffuse
Speaker 4: to build any complex structures.
Speaker 2: So you need a liquid, a liquid canvas for the
Speaker 2: chemistry to happen.
Speaker 4: I like that, Yes, a canvas, and water acts as
Speaker 4: this incredibly versatile canvas. I mean it remains liquid over
Speaker 4: a massive stable temperature range from zero to one hundred
Speaker 4: degrees celsius at standard atmospheric.
Speaker 2: Pressure, which is a huge window.
Speaker 4: It's a massive playground for biology. And furthermore, water molecules
Speaker 4: are polar.
Speaker 2: Oh right, The polarity.
Speaker 4: Yeah, they have a distinct V shape, right, Yeah, with
Speaker 4: the oxygen atom pulling electrons slightly toward itself. So this
Speaker 4: gives the oxygen and a slight negative charge and the
Speaker 4: hydrogen ends a slight positive.
Speaker 2: Charge, which makes them act like tiny little magnets.
Speaker 4: Exactly, And the polarity allows them to form what we
Speaker 4: call hydrogen bonds.
Speaker 2: And those hydrogen bonds are like the sticky little connections
Speaker 2: that hold biological structures together.
Speaker 4: Right, you nailed it. They're weak enough to be broken
Speaker 4: and reformed easily, which you absolutely need for dynamic processes
Speaker 4: like copy genetic material, but they're strong enough to stabilize massive.
Speaker 2: Biomolecules like DNA.
Speaker 4: Like DNA, when you look the iconic double helix, it
Speaker 4: is held together right down the middle by hydrogen bonds.
Speaker 2: That's amazing.
Speaker 4: And even the way proteins fold themselves into those complex
Speaker 4: three dimensional shapes, which is how they act as the
Speaker 4: microscopic machines in our cells, that is entirely dictated by
Speaker 4: how they interact with the surrounding water molecules.
Speaker 2: Wait, so the water is actually forcing the proteins into
Speaker 2: shape exactly.
Speaker 4: Some parts of the protein are attracted to water, and
Speaker 4: some parts are repelled by it. That push and pull
Speaker 4: literally forces the protein to fold into a very specific
Speaker 4: functional shape.
Speaker 2: So the water isn't just a passive background liquid that
Speaker 2: things float in. It is an active structural participant in
Speaker 2: the architecture of the cell.
Speaker 4: It's the scaffolding, the transportation network, and the climate control
Speaker 4: system all rolled into one.
Speaker 2: Climate control How does it do that?
Speaker 4: Well, water possesses an extraordinarily high heat capacity. That means
Speaker 4: it can absorb a massive amount of thermal energy before
Speaker 4: its actual temperature rises significantly.
Speaker 2: Oh so it buffers against temperature swings.
Speaker 4: Right, It buffers our entire planet and the delicate organisms
Speaker 4: on it against wild lethal shifts in temperature. A puddle
Speaker 4: of water doesn't just boil instantly when the sun hits it.
Speaker 2: And the ocean doesn't freeze solid the second winter arrives, exactly.
Speaker 4: It facilitates nutrient transport, sweeps away cellular waste, and keeps
Speaker 4: the whole system stable. Water is undeniably fantastic.
Speaker 2: Five stars for water, absolutely, But you know our current
Speaker 2: astrobiology strategy. It feels a bit like that old joke,
Speaker 2: which one the one about the guy looking for his
Speaker 2: lost keys. Under the street light. Someone asks him, Hey,
Speaker 2: did you lose them here? And he says, no, I
Speaker 2: lost them over in the dark park. But the light
Speaker 2: is better over here.
Speaker 4: Ah, yes, the street light effect.
Speaker 2: Right. We know how water works, so we only look
Speaker 2: for water. But isn't it incredibly arrogant to assume the
Speaker 2: rest of the cosmos plays by Earth's very specific chemical rules.
Speaker 4: A lot of researchers would agree with you. In fact,
Speaker 4: the scientific community literally calls that chemical chauvinism.
Speaker 2: Chemical chauvinism. I love that term.
Speaker 4: It's very fitting. Many researchers acknowledge this bias, but they
Speaker 4: argue it is borne out of strict financial and logistical necessity.
Speaker 2: Because space exploration is so staggeringly expensive.
Speaker 4: Exactly sending a probe to another planet costs billions of dollars.
Speaker 4: If you only have the budget for one single mission,
Speaker 4: you send it to the place where you know unequivocally
Speaker 4: that the chemistry works.
Speaker 2: You bet on the sure thing. Water is a proven concept.
Speaker 3: Right.
Speaker 4: If we restrict our search strictly to this follo of
Speaker 4: the water mantra, however, we do run the massive risk
Speaker 4: of being completely blind to entirely different categories of habitable worlds.
Speaker 2: So let's say we stuck out of the light of
Speaker 2: that earthlike street light. Let's consider that water isn't the
Speaker 2: only game in town. What other liquids could potentially act
Speaker 2: as the canvas for complex biology.
Speaker 4: Well, let's turn down the thermostat. Let's head into the
Speaker 4: deep freeze.
Speaker 2: Okay, I'm grabbing my coat. Where are we going?
Speaker 4: If you move outward in any solar system, away from
Speaker 4: the warmth of the host star, water inevitably turns to
Speaker 4: solid ice, right, and once it freezes, it becomes useless
Speaker 4: as a biological solvent. It essentially just becomes a rock.
Speaker 4: But other chemical compounds suddenly become viable liquids at those
Speaker 4: extreme negative temperatures.
Speaker 2: So what are the top contenders.
Speaker 4: Two of the most prominent candidates for alien solvents are
Speaker 4: liquid ammonia and liquid hydrocarbons.
Speaker 2: Let's look at ammonia first NH three. I mean, on Earth,
Speaker 2: we mostly know it as that really pungent chemical in
Speaker 2: window cleaners or fertilizer.
Speaker 4: Yeah, it has a very distinct smell.
Speaker 2: How does a harsh cleaning chemical support a delicate biological ecosystem.
Speaker 4: Well, first of all, ammonia is cosmically abundant. It forms
Speaker 4: easily in the massive molecular clouds that birth star systems,
Speaker 4: but crucially, at standard atmospheric pressure. It exists as a
Speaker 4: liquid between negative seventy eight degrees and negative thirty three
Speaker 4: degrees celsius.
Speaker 2: So it's liquid at very cold temperatures exactly.
Speaker 4: And just like water, ammonia molecules are polar.
Speaker 2: Oh, so they can do the magnet thing.
Speaker 4: Yes, The nitrogen atom pulls electrons away from the hydrogen atoms,
Speaker 4: creating a dipole. This means liquid ammonia is highly capable
Speaker 4: of forming hydrogen.
Speaker 2: Bonds, meaning it could build the scaffolding for cells right.
Speaker 4: It can dissolve many organic compounds, meaning it could absolutely
Speaker 4: support a rich complex organic chemistry.
Speaker 2: But operating at negative seventy eight degrees celsius I mean
Speaker 2: that presents a huge thermodynamic hurdle, doesn't it.
Speaker 4: It is significantly colder, yes, and ammonia is also a
Speaker 4: bit more chemically reactive than water. It has a tendency
Speaker 4: to attack and break down certain delicate biomolecules that water
Speaker 4: would safely cradle.
Speaker 2: So it's a bit of a double edged sword it is.
Speaker 4: However, ammonia and water don't have to be mutually exclusive.
Speaker 4: In an ammonia water mixture, the ammonia actually acts as
Speaker 4: a potent antifreeze.
Speaker 2: Oh wow, like in a car radiator, Exactly like that.
Speaker 4: It dramatically depresses the freezing point of the mixture. So
Speaker 4: you could have subterranean oceans on on icy world's places,
Speaker 4: incredibly far outside the traditional habitable zone that remains slushy
Speaker 4: and liquid at temperatures that would freeze pure water into
Speaker 4: solid granite.
Speaker 2: That immediately makes me think of the icy moons further
Speaker 2: out in our own solar system. But wait, we can
Speaker 2: push the temperature even lower, right you can. Let's talk
Speaker 2: about the hydrocarbons on Titan, Saturn's largest moon, Titan is
Speaker 2: just wild.
Speaker 4: Titan is an absolute astrobiologists stream. It stands as the
Speaker 4: only other body in our entire solar system with stable
Speaker 4: flowing bodies of liquid right on its surface.
Speaker 2: But it is unimaginably cold there.
Speaker 3: Very cold.
Speaker 4: The surface temperature hovers around negative one hundred and seventy
Speaker 4: nine degrees.
Speaker 2: Celsius negative one hundred and seventy nine degrees. At that temperature,
Speaker 2: water is not a liquid, It's not even a slush.
Speaker 2: It is literally a mineral.
Speaker 4: Right it forms the actual geological bedrock of the Moon.
Speaker 4: Water ice on Titan is as hard at terrestrial granite.
Speaker 2: That's crazy, but.
Speaker 4: Raining from the sky carving deep branching river valleys into
Speaker 4: that ice rock in massive stable lakes and seasier the
Speaker 4: poles are liquid hydrocarbons.
Speaker 2: Specifically, it's a mixture of methane and ethane, right.
Speaker 4: Correct, But here is the massive chemical roadblock with a
Speaker 4: hydrocarbon ocean.
Speaker 2: Okay, lay it on me.
Speaker 3: You remember how.
Speaker 4: We just talked about water and ammonia being polar. How
Speaker 4: that allows them to do that sticky tape hydrogen bonding
Speaker 4: action to fold proteins and build cell membranes.
Speaker 2: Yeah, the tiny magnets.
Speaker 4: Well, methane and ethane are completely non polar. The electrical
Speaker 4: charge is distributed evenly across the whole molecule. They don't
Speaker 4: have those charged magnetic ends.
Speaker 2: Wait, really, so how do molecules even interact or dissolve
Speaker 2: if the liquid isn't polar?
Speaker 3: That is the big question.
Speaker 2: Wouldn't life at negative one hundred and seventy nine degrees
Speaker 2: just freeze and shatter? Like? How do you even build
Speaker 2: a functional enclosed cell? In a lake of liquid natural gas.
Speaker 4: This is exactly where we have to totally throw out
Speaker 4: the Earth biology rule book. Yeah, you cannot just drop
Speaker 4: an Earth's cell into liquid methane.
Speaker 2: It would just die instantly, instantly.
Speaker 4: Our proteins are DNA, our lipid membranes, they all rely
Speaker 4: on what we call the hydrophobic effect generated by polar water.
Speaker 4: In a non polar solvent like methane, an Earthly cell
Speaker 4: membrane wouldn't even.
Speaker 3: Hold its shape.
Speaker 2: What would happen to it?
Speaker 4: It would essentially turn inside out or its components would
Speaker 4: just dissolve and disperse completely into the liquid.
Speaker 2: Oh, because lipids on Earth have a water loving head
Speaker 2: and a water hating tail, right, and they arrange themselves
Speaker 2: into a sphere specifically to hide the tails from.
Speaker 4: The water a perfect description.
Speaker 2: So in methane there's no water to hide from, so
Speaker 2: the sphere just falls apart.
Speaker 4: Precisely so, life in a non polar hydrocarbon ocean would
Speaker 4: need completely different structural scaffolding.
Speaker 2: What would that even look like?
Speaker 4: Instead of relying on our familiar proteins and amino acids,
Speaker 4: a tight native might build its cellular structures out of
Speaker 4: long chain hydrocarbons or highly specialized nitrogen bearing molecules molecules
Speaker 4: that naturally assemble into membranes in a non polar environment
Speaker 4: that is wild, and they would use water soluble sugars
Speaker 4: for energy either, they would likely utilize the abundant organic
Speaker 4: compounds that are constantly raining down from Titan's thick, photochemically
Speaker 4: active atmosphere.
Speaker 2: Okay, but the temperature is still the elephant in the
Speaker 2: room here negative one hundred and seventy nine degrees celsius.
Speaker 4: Yes, thermodynamics is a strict master.
Speaker 2: Because everything slows down when it's cold. I mean, we
Speaker 2: put food in the freezer specifically to stop chemical reactions
Speaker 2: from making it go bad. So how does a biological
Speaker 2: entity actually do anything at a temperature where chemistry practically
Speaker 2: grinds to a halt.
Speaker 4: This is where we have to introduce the concept of
Speaker 4: slower time. Chemical reaction rates are deeply mathematically dependent on temperature.
Speaker 4: As you lower the ambient heat, molecules possess less kinetic energy,
Speaker 4: They jiggle less, they bump into each other much less frequently,
Speaker 4: and the energy available to break and form new chemical
Speaker 4: bonds drops off a massive cliff.
Speaker 2: So their entire existence would be operating on this radically
Speaker 2: stretched temper scale exactly.
Speaker 4: Life in liquid methane would be profoundly slow metabolizing. If
Speaker 4: we think of a typical metabolic chemical reaction in an
Speaker 4: Earth cell, taking say a fraction.
Speaker 2: Of a second, which happens constantly, right.
Speaker 4: An equivalent biological.
Speaker 2: A longer complete wait, So an organism's lifespan, it's cellular reproduction,
Speaker 2: it's physical movement across the seabed, it would all be
Speaker 2: agonizingly stretched out absolutely.
Speaker 4: Observing a Titan ecosystem with human eyes might look completely static.
Speaker 4: It might just look like a frozen tableau or a landscape.
Speaker 2: Of rock, like nothing is happening at all.
Speaker 4: Right, But if you set up a time lapse camera
Speaker 4: and watched it over decades or centuries, only then would
Speaker 4: you see organisms slowly moving, feeding, exchanging chemicals and dividing.
Speaker 2: That is so eerie.
Speaker 4: Because the thermal energy available is so incredibly low, absolute
Speaker 4: metabolic efficiency and extreme patients become the primary driving evolutionary forces.
Speaker 2: Picturing Titan's landscape through this lens is just haunting. You
Speaker 2: have a hazy sky raining liquid methane rivers actively carving
Speaker 2: canyons into water ice bedrock, and the potential for a
Speaker 2: slow motion, non polar ecosystem operating completely invisibly beneath our
Speaker 2: current planetary probes.
Speaker 3: It's very possible.
Speaker 2: I mean, when the Cassini Huygens mission dropped a probe
Speaker 2: through Titan's atmosphere back in two thousand and five, it
Speaker 2: landed on a damp floodplaine and photographed these rounded, smooth
Speaker 2: ice cobbles.
Speaker 3: I remember those images.
Speaker 2: What if there was a biosphere right there in front
Speaker 2: of the lens, But its metabolism is so slow and
Speaker 2: its chemistry is so radically non polar that our sensors
Speaker 2: just interpreted it as complex carbon rich dirt.
Speaker 4: It is entirely within the realm of possibility. We wouldn't
Speaker 4: even recognize it as life. And while methane and ethane
Speaker 4: are the obvious stars of the show on Titan, chemists
Speaker 4: have modeled other exotic alternative solvents for extreme cold or
Speaker 4: high pressure conditions too. Oh like what else compounds like formamide,
Speaker 4: hydrogen fluoride, or even certain liquid salts that remains stable
Speaker 4: and fluid in environments where water would just instantly boil
Speaker 4: or freeze solid.
Speaker 2: The options are wider than we think exactly.
Speaker 4: The overarching point is that the liquid canvas for biology
Speaker 4: doesn't strictly have to.
Speaker 3: Be h two zero.
Speaker 2: Well, if extreme cold forces life to stretch time to
Speaker 2: solve the energy problem, it makes me wonder how life
Speaker 2: solves the opposite problem, touch energy exactly? What about environments
Speaker 2: with far too much violent energy, places where the heat
Speaker 2: and the aggressive chemistry are actively trying to tear complex
Speaker 2: molecules apart. Let's look at the ultimate acid.
Speaker 4: Test ah sulfuric acil.
Speaker 2: Furic acid, which brings us directly to Venus. Venus is
Speaker 2: frequently called Earth's evil twin right.
Speaker 4: Very evil. Its rocky surface is a literal hellscape. Temperatures
Speaker 4: are around four hundred and seventy degrees celsius, and it
Speaker 4: has a crushing atmospheric pressure roughly ninety times out of Earth.
Speaker 2: So nothing is surviving down there.
Speaker 4: No, the surface is basically a dead end for biology
Speaker 4: as we understand it. But if you ascend about fifty
Speaker 4: kilometers up into the Venusian atmosphe the temperature and pressure
Speaker 4: are surprisingly earth like. They hover right around room temperature.
Speaker 2: Oh really, that sounds quite pleasant.
Speaker 4: Well, don't pack your bags just yet. The major catch
Speaker 4: is the composition of the clouds. They are made of
Speaker 4: highly concentrated liquid sulfuric acid droplets.
Speaker 2: Which is terrifying to even conceptualize. Sulfuric acid eats through
Speaker 2: solid metal. It does if you expose organic matter to
Speaker 2: it's a piece of water, a piece of meat, It
Speaker 2: turns black, violently boils, and just dissolves into sludge. It
Speaker 2: is so hard to imagine how that environment could host life.
Speaker 2: I used to picture it like trying to build a delicate,
Speaker 2: intricate house of cards while inside a wind tunnel.
Speaker 4: That's a great visual, But it's not a kinetic destruction,
Speaker 4: is it. It's a chemical destruction, right.
Speaker 2: That distinction is crucial. It seems impossible to us because
Speaker 2: our biology is fundamentally built on carbon water chemistry.
Speaker 3: Exactly.
Speaker 4: We have to understand why sulfuric acid destroys earth life
Speaker 4: so violently.
Speaker 2: Okay, break it down for me.
Speaker 4: Sulfuric acid is intensely hygrosspic meaning it is incredibly greedy
Speaker 4: for water. It doesn't just dissolve the physical structure, It
Speaker 4: actively rips the hydrogen and oxygen atoms right out of
Speaker 4: the molecular structure of carbohydrates and proteins. Just to form
Speaker 4: water for itself.
Speaker 2: Oh wow, so it's stealing the water from the cells.
Speaker 4: Precisely that black sledge left behind. That is just the
Speaker 4: dead carbon skeleton that remains after the water has been
Speaker 4: chemically stolen.
Speaker 2: So it's not that the acid is fundamentally anti life,
Speaker 2: it's just specifically anti water based life.
Speaker 4: You hit the nail on the head. An organism native
Speaker 4: to a sulfuric acid environment wouldn't be fighting the acid,
Speaker 4: it would be utilizing it as its primary solvent instead
Speaker 4: of water exactly. Sulfuric acid is actually a fantastic solvent
Speaker 4: in its own right. It remains liquid over an enormous
Speaker 4: temperature range, much larger than water. Furthermore, it forms incredibly strong,
Speaker 4: complex hydrogen bonding networks.
Speaker 2: So it operates on similar chemical principles to water.
Speaker 4: Yes, you still get that sticky scaffolding that allows for
Speaker 4: complex three dimensional biological structures to fold and hold their shape.
Speaker 2: But the molecular building blocks would have to be entirely different.
Speaker 4: Right, Oh completely. A Venusia microbe floating in those clouds
Speaker 4: wouldn't use our specific DNA or proteins because the acid
Speaker 4: would immediately dehydrate.
Speaker 2: And shred them right, It would turn them to sludge.
Speaker 4: It would use entirely different acid stable polymers for its
Speaker 4: genetics and its internal catalysis. It would build its cellular
Speaker 4: machinery out of molecules that are highly resistant to being
Speaker 4: oxidized or dehydrated. That is fascinating, and this actually brings
Speaker 4: us to one of the most exciting theoretical possibilities in astrobiochemistry.
Speaker 2: I think I know where you're going with.
Speaker 4: This silicon based life.
Speaker 2: The silicon dream. It's a massive staple of science fiction.
Speaker 2: But from a practical standpoint, on Earth, silicon doesn't really
Speaker 2: do anything biologic, does it not?
Speaker 3: Really?
Speaker 2: No, it just sits there inertly as sand or quartz
Speaker 2: or glass.
Speaker 4: Right, But the theoretical appeal of silicon lies in this
Speaker 4: position on the periodic table.
Speaker 2: It sits right below carbon exactly.
Speaker 4: Sitting directly below carbon means it shared carbon's ability to
Speaker 4: form four simultaneous chemical.
Speaker 2: Bonds, so it can build complex stuff.
Speaker 4: In pure theory, it should be able to create the long,
Speaker 4: complex chains, branching structures and rings that carbon dies, the
Speaker 4: very architectural backbone of complex molecules.
Speaker 2: So why doesn't it do that on Earth?
Speaker 4: Well, on Earth, in an oxygen rich, water based environment,
Speaker 4: silicon bonds are relatively weak and unstable. When silicon encounters
Speaker 4: water and oxygen, it almost immediately oxidizes into silica silicon dioxide.
Speaker 2: So in water, silicon just instantly bricks itself into sand.
Speaker 2: It locks into a rigid, dead lattice.
Speaker 4: Exactly when oxygen and water are present, silicon oxygenve bonds
Speaker 4: form so rapidly and strongly that they overpower any complex
Speaker 4: silicon chains. It turns everything into an inert rock crystal.
Speaker 2: But what if you remove the water?
Speaker 3: Ahuh?
Speaker 4: When you remove the water and intury use a highly acidic,
Speaker 4: non aqueous solvent like concentrated sulfuric acid, the chemistry completely flips.
Speaker 2: Wait really yes, in a.
Speaker 4: Highly acidic environment, those complex silicon compounds suddenly become incredibly stable.
Speaker 4: They can form beautifully diverse complex chains and structures that
Speaker 4: carbon actually struggles to maintain under those exact same extreme conditions.
Speaker 2: Let's visualize this, because my mind is just doing backflips
Speaker 2: trying to imagine a biological creature made of silicon living
Speaker 2: in a cloud of battery acid or on a hyper arid,
Speaker 2: rocky planet. What does a silicon organism actually look like.
Speaker 4: Structurally, silicon biology might feature crystalline like matrices or robust
Speaker 4: acid resistant polymers rather than the squishy, fleshy lipid membranes
Speaker 4: we are familiar with on Earth.
Speaker 2: So they'd be sort of glassy or.
Speaker 4: Rock like potentially, and because of the inherent thermal stability
Speaker 4: of silicon bonds, these organisms might thrive at temperatures that
Speaker 4: would completely vaporize liquid water.
Speaker 2: That is wild.
Speaker 3: But the most.
Speaker 4: Striking visible difference likely be their daily metabolism and specifically
Speaker 4: their physical waste products.
Speaker 2: Okay, walk me through that. On Earth, we eat carbon
Speaker 2: based food, our bodies reacted with oxygen, and we exhale
Speaker 2: carbon dioxide, which is a gas that just floats away. Right,
Speaker 2: what does a silicon creature do when it metabolizes its food.
Speaker 4: Well, if a silicon based organism is processing silicon analogs
Speaker 4: of sugars or hydrocarbons for energy, and it uses oxygen
Speaker 4: or an oxygen compound in that reaction, its metabolic byproduct
Speaker 4: wouldn't be a gas like carbon dioxide.
Speaker 2: Because silicon dioxide is.
Speaker 4: Silicon dioxide at any reasonable planetary temperature is a solid.
Speaker 2: Its metabolic waste product would be solid silica.
Speaker 4: Yes, it would essentially exhale solid grains of sand.
Speaker 2: That is absolutely staggering. You have a life form that
Speaker 2: takes an energy and periodically excretes solid quartz dust or
Speaker 2: fine sand as a natural waste product, just the same
Speaker 2: way we exhale a breath.
Speaker 4: It's hard to wrap your head around, isn't it. It represents
Speaker 4: a completely alien biological paradigm, it really does. It implies
Speaker 4: that rocky, highly acidic or hyper arid worlds that astronomers
Speaker 4: currently dismiss as entirely barren or geologically dead, they could
Speaker 4: actually be covered in a slow moving crystalline biosphere that
Speaker 4: is perfectly elegantly adapted to its extreme environment.
Speaker 2: So we've completely swapped out the canvas. We've taken the
Speaker 2: liquid solvent and replaced cozy, familiar water with freezing ammonia,
Speaker 2: liquid methane, and literal concentrated acid.
Speaker 3: We've made things very weird.
Speaker 2: Extremely weird. But the liquid medium is only half the
Speaker 2: equation for complex life on Earth. Right to get big,
Speaker 2: to build complex nervous systems, to be highly mobile and
Speaker 2: hunt Earth life relies on an incredibly potent, highly volatile fuel,
Speaker 2: and that fuel is oxygen.
Speaker 4: The oxygen problem. It is arguably the single biggest bottleneck
Speaker 4: in theoretical astrobiology because.
Speaker 2: It's one thing to have a single cell surviving an
Speaker 2: acid right exactly.
Speaker 4: While it is relatively easy to model simple, slow moving,
Speaker 4: single celled microbes surviving in extreme exotic solvents, scaling up
Speaker 4: from a microbe to complex multicellular life with differentiated tissues
Speaker 4: like muscles, organs, and brains that requires an incredibly dense,
Speaker 4: highly reactive energy source.
Speaker 2: Let's do a really close look into the actual mechanics
Speaker 2: of oxygen. I mean, we breathe it in every second
Speaker 2: of every day, But what is it actually doing on
Speaker 2: a microscopic chemical level that makes it so utterly indispensable
Speaker 2: for complex animal life.
Speaker 4: Well, chemically speaking, oxygen is a ferocious electron acceptor.
Speaker 2: What does that mean? Exactly?
Speaker 4: It is highly electronegative, meaning it strongly pulls electrons toward itself.
Speaker 4: In the biological process of cellular respiration, our bodies are
Speaker 4: essentially conducting a highly controlled, incredibly slow motion fire.
Speaker 2: Okay, I like that analogy.
Speaker 4: We are taking the food we eat glucose and methodically
Speaker 4: pulling high energy electrons off of it. We pass those
Speaker 4: electrons down a complex biological assembly line inside ourselves to
Speaker 4: extract energy at every single step. But at the very
Speaker 4: end of that assembly line, something needs to catch those
Speaker 4: spent electrons to clear the line and keep the current flowing.
Speaker 2: Like someone catching the buckets at the end of a
Speaker 2: bucket brigade.
Speaker 4: Exactly, and oxygen sits at the end of that chain.
Speaker 4: It is phenomenally good at catching those electrons.
Speaker 2: Because it's so chemically hungry for them.
Speaker 4: Right, and the energy payoff for using oxygen as the
Speaker 4: catcher is massive. The thermodynamic yield is staggering.
Speaker 2: How much of a difference does it actually make.
Speaker 4: Aerobic respiration the process of using oxygen to catch those electrons,
Speaker 4: yields roughly eighteen times more usable cellular energy per single
Speaker 4: molecule of glucose compared to anaerobic processes like simple fermentation,
Speaker 4: which don't use oxygen.
Speaker 2: Eighteen times more energy from the exact same piece of food.
Speaker 3: It's a huge leap.
Speaker 2: It's like upgrading from a sluggish dial up internet connection
Speaker 2: where it takes ten minutes to load a single image
Speaker 2: to instantly getting gigabit fiber optic broadband. It allows for
Speaker 2: a massive surge and data oxygen suddenly allows for high
Speaker 2: bandwidth biology.
Speaker 4: I love the broadband analogy that massive eighteen fold energy
Speaker 4: boost is the fundamental reason complex animals exist at all.
Speaker 4: It powers large multicellular body plans.
Speaker 2: It gives organisms the sheer physical power to fight gravity
Speaker 2: and walk on land.
Speaker 4: It fuels active, fast twitch muscle movement for pursuing prey
Speaker 4: and escaping predators. And above all, it powers the brain.
Speaker 2: Right because brains are energy hogs.
Speaker 4: Neurological tissue is an incredibly expensive biological.
Speaker 3: Organ to run.
Speaker 4: From an energy standpoint, you simply cannot run a complex
Speaker 4: brain on the meager energy yields of fermentation.
Speaker 2: And the fossil record on Earth completely backs this up,
Speaker 2: doesn't it. For billions of years, our planet was basically
Speaker 2: just a giant pond of slime, just single celled anaerobic
Speaker 2: microbes hanging out in a soup, not really doing much
Speaker 2: of anything.
Speaker 4: Earth's own monumental leaped and biological complexity didn't happen until
Speaker 4: a planetary event known as the Great Oxidation Event roughly
Speaker 4: two point four billion years ago. What costs that ancient
Speaker 4: cyano bacteria evolved a genetic mutation that allowed them to photosynthesize.
Speaker 4: They started using sunlight to split water molecules, and this
Speaker 4: process released free oxygen as a chemical waste product.
Speaker 2: Oh, so they just started pumping it into the atmosphere.
Speaker 3: Yes.
Speaker 4: And initially this free oxygen was highly toxic. It literally
Speaker 4: poisoned almost everything on the planet, causing a massive mass extinction.
Speaker 2: Wow.
Speaker 4: But over millions of years, once life adapted to harness
Speaker 4: that volatile oxygen, instead of being destroyed by it, biology
Speaker 4: absolutely exploded in size, complexity, and diversity.
Speaker 2: So oxygen is the absolute fiber optic upgrade for a biosphere.
Speaker 2: But here is the multimillion dollar astrobiology question.
Speaker 3: I'm ready.
Speaker 2: Are there any complex multicellular creatures right here on Earth
Speaker 2: that completely bypassed this broadband upgrade? Did anything manage to
Speaker 2: get big and complex without ever touching an oxygen molecule?
Speaker 3: Surprisingly?
Speaker 2: Yes?
Speaker 3: Wait, really yes?
Speaker 4: And their existence challenges everything biologists thought they knew about zoology.
Speaker 2: Okay, tell me about these things.
Speaker 3: Well.
Speaker 4: For decades, science knew that simple, single celled anaerobes thrived
Speaker 4: in oxygen free niches places like deep mud sediments, sculling
Speaker 4: hydrothermal vents, and the dark depths of animal digestive tracts.
Speaker 2: Sure microbes can live anywhere.
Speaker 4: But complex multicellular animals, the strict assumption was that they
Speaker 4: absolutely required oxygen to maintain their cellular structures. Until researchers
Speaker 4: started looking at the absolute most hostile places on the seafloor.
Speaker 2: Where did they look?
Speaker 4: The major turning point was the discovery of incredibly bizarre
Speaker 4: microscopic multicellular animals called lurisciffrons lurisiferns. Yes, they were found
Speaker 4: deep in the Mediterranean seafloor within the l Atlante basin.
Speaker 2: What exactly is a lur cifern and where are they living?
Speaker 4: They are tiny, visually resembling microscopic jellyfish or heavily armored
Speaker 4: cup shaped organisms, But their physical appearance isn't the major
Speaker 4: scientific headline here.
Speaker 2: It's where they live, right.
Speaker 4: They were dredged up from deep hyperslene and oxic brine basins.
Speaker 4: That sounds an hens These are dense pools of hypersalty
Speaker 4: water sitting at the bottom of the ocean where there
Speaker 4: is absolutely zero dissolved oxygen none. Instead, the water is
Speaker 4: packed with toxic hydrogen.
Speaker 2: Sulfide and they just live down there.
Speaker 4: Scientists found these multicellular animals living their entire life cycles, reproducing, moving,
Speaker 4: and thriving completely without oxygen.
Speaker 2: How is that mechanically possible? If they don't have oxygen
Speaker 2: to act as that crucial electron catcher at the bottom
Speaker 2: of the cellular assembly line, what is keeping the chemical
Speaker 2: current flowing well?
Speaker 4: Normally, animal cells utilize mitochondria, the famous powerhouses of the cell,
Speaker 4: and mitochondrias strictly rely on oxygen. Lricifrins lack mitochondria completely,
Speaker 4: Oh wow. Instead, their cells contain highly specialized evolutionary distinct
Speaker 4: organelles called hydrogenosomes. Hydrogenosomes, Yes, these organelles extract energy through
Speaker 4: a completely different biochemical pathway. They don't use oxygen to
Speaker 4: catch the final electron. Instead, they use protons, and the
Speaker 4: resulting chemical reaction produces hydrogen gas as a waste product.
Speaker 2: That's incredible. It's like finding out your neighbour's high performance
Speaker 2: sports car doesn't run on gasoline or electricity, but somehow
Speaker 2: manages to run perfectly on swamp gas and sheer willpower.
Speaker 4: That's a very colorful way to put it, but it's
Speaker 4: pretty accurate. It proves definitively that multicellularity without oxygen is
Speaker 4: physically and mechanically possible.
Speaker 2: That opens up so many doors.
Speaker 4: It does, and when we look deep into our own
Speaker 4: evolutionary past, recent microbiological research into asgard Arkaia reveals a
Speaker 4: fascinating dynamic about the transition to complex life.
Speaker 2: As guard Arkaia named after Norse mythology right exactly.
Speaker 4: They were discovered in deep sea sediment near a hydrothermal
Speaker 4: vent system called Loki's Castle, hence the mythological naming convention
Speaker 4: got it. Asguard Urkaia are currently considered the closest living
Speaker 4: microbial relatives to the ancient ancestors of all complex the
Speaker 4: eukaryotic life that includes animals, plants, and fungi, So.
Speaker 2: They are like our deep deep evolutionary cousins.
Speaker 4: Right And while many asgard Archaea are strict anaerobes, recent
Speaker 4: genomics studies show that some lineages possess the metabolic machinery
Speaker 4: to tolerate or even actively utilize small trace amounts of oxygen.
Speaker 2: So this implies that while the loarciferns are surviving without
Speaker 2: oxygen right now, the original evolutionary machinery required to build
Speaker 2: a complex cell in the first place might still have
Speaker 2: relied on encountering that initial oxygen bottleneck.
Speaker 4: It's a very real possibility, which brings.
Speaker 2: Up a really concerning massive thought for astrobiology and the
Speaker 2: search for.
Speaker 4: Habitable worlds is a time factor.
Speaker 2: Yes, if oxygen takes billions of years to slowly build
Speaker 2: up in a planet's atmosphere like it did here on Earth,
Speaker 2: what happens on an alien planet that simply doesn't have
Speaker 2: that kind of time.
Speaker 4: This is what we call the oxygenation time bottleneck, and
Speaker 4: it fundamentally alters how we calculate planetary habitability. On Earth,
Speaker 4: it took over two billion years of relentless microbial photos
Speaker 4: synthesis to slowly saturate the oceans and build up enough
Speaker 4: atmospheric oxygen to support large animals.
Speaker 2: Lu billion years is a massive stretch of cosmic time.
Speaker 4: It is many stars in the galaxy simply do not
Speaker 4: burn that long, or they are too volatile. If an
Speaker 4: Earth sized planet orbits a short lived star, or if
Speaker 4: the planet orbits a highly active red dwarf that constantly
Speaker 4: strips the atmosphere away with stellar flares, oxygen might never accumulate.
Speaker 2: It just gets blown away before it builds up.
Speaker 4: Exactly Furthermore, if a planet's crust geology acts as a
Speaker 4: massive chemical sink, meaning it is rich in unoxidized iron
Speaker 4: or other minerals that constantly absorb free oxygen as fast
Speaker 4: as microbes produce it, that planet might never experience an oxygenation.
Speaker 2: Event because the rocks are just soaking it all up right.
Speaker 4: It could remain warm, wet, and habitable for billions of years,
Speaker 4: but be permanently trapped hosting only simple, low energy, single
Speaker 4: celled microbial life.
Speaker 2: It would be a biosphere trapped in the dial Up
Speaker 2: era forever.
Speaker 3: Exactly.
Speaker 2: So, if oxygen is this incredibly strict, difficult bottleneck to pass,
Speaker 2: how could a truly alien ecosystem fuel complex, fast moving
Speaker 2: intelligent life without it? What are the high energy alternative
Speaker 2: fuels available in the cosmos?
Speaker 4: Well, if an alien biology isn't utilizing oxygen, it requires
Speaker 4: another highly potent electronic sceptor to generate that massive energy yield,
Speaker 4: and planetary chemistry offers several fascinating, highly reactive candidates.
Speaker 2: What is the alternative rocket fuel of the weird cosmos?
Speaker 4: One theoretical option is utilizing stronger oxidants that naturally occur
Speaker 4: in exotic irradiated environments, compounds like hydrogen peroxide, perchlorates or
Speaker 4: various highly reactive sulfur compounds perchlorates. Yes, perchlorates are highly
Speaker 4: reactive toxic salts that we now know are abundantly spread
Speaker 4: throughout the Martian soil.
Speaker 2: Oh right, And hydrogen peroxide. That's the exact same liquid
Speaker 2: in the brown bottle from the pharmacy that foams up
Speaker 2: violently when you pour it on a cut.
Speaker 4: That's the one. And do you know why it foams?
Speaker 4: Why it foams on a cut because enzymes in your
Speaker 4: blood are frantically breaking it down into water and oxygen
Speaker 4: to protect your cells from its destructive oxidizing power.
Speaker 2: Wait really, I always thought it was just bubbling away
Speaker 2: the dirt.
Speaker 4: No, it is toxic to us because it aggressively damages
Speaker 4: our specific cellular machinery. But an alien organism that evolved
Speaker 4: alongside it and structurally adapted to handle it, could theoretically
Speaker 4: utilize a hydrogen peroxide water mixture both as an intracellular,
Speaker 4: anti free solvent and as an incredibly dense, high energy
Speaker 4: metabolic fuel that is.
Speaker 2: A staggering biological engine running on pure hydrogen peroxide. It
Speaker 2: would be very powerful what other mechanisms could drive life
Speaker 2: without oxygen.
Speaker 4: Another deeply studied alternative is chemolithotrophy.
Speaker 2: Chemolithotrophy That sounds complicated.
Speaker 4: The word literally translates to rock eating metabolism.
Speaker 2: Oh, that's awesome.
Speaker 4: These specific organisms bypass the need for sunlight and oxygen entirely.
Speaker 4: They extract their life energy by exploiting tiny thermoe dynamic
Speaker 4: chemical gradients in solid inorganic matter.
Speaker 2: How do they do that?
Speaker 4: They actively pull electrons directly from minerals like oxidized iron, manganese,
Speaker 4: or even free hydrogen gas percolating from the crust. They
Speaker 4: often react them with sulfates or nitrates to complete the
Speaker 4: biological circuit.
Speaker 2: So they're essentially living biological batteries, just drawing an electrical
Speaker 2: current straight out of the planetary bedrock exactly.
Speaker 4: And we observe this happening right now in the deepest, darkest,
Speaker 4: most crushing parts of Earth's oceans, clustering around hydrothermal.
Speaker 2: Vents right the deep sea stuff.
Speaker 4: But on an alien world, perhaps a rogue planet wandering
Speaker 4: in the dark without a star, or a world with
Speaker 4: a permanently opaque atmosphere, chemolithotrophy could be the absolute dominant
Speaker 4: planetary food web, operating entirely independent of stellar energy and
Speaker 4: atmospheric oxygen.
Speaker 2: Okay, let me push back on this a bit of it.
Speaker 2: If all these incredible thermodynamic alternatives exist in nature, if
Speaker 2: you can run a thriving biosphere on hydrogen peroxide or
Speaker 2: by literally eating the iron out of rocks, why did
Speaker 2: Earth life overwhelmingly choose oxygen.
Speaker 3: That's a great question.
Speaker 2: Is oxygen just inherently chemically superior or did oxygen just
Speaker 2: happen to win the evolutionary lottery on the specific planet.
Speaker 4: It is a combination of both thermodynamic efficiency and planetary context.
Speaker 4: From a pure mathematical thermodynamic standpoint, oxygen is undeniably one
Speaker 4: of the most efficient, readily available electronic acceptors in.
Speaker 2: The universe, provided you have the right setup.
Speaker 4: Exactly, provided you are on a water based, carbon rich
Speaker 4: planet exposed to adequate sunlight, it is cosmically abundant, easily
Speaker 4: liberated from water by photons, and the energy payout is massive.
Speaker 4: On Earth, oxygen was the obvious dominant winning ticket.
Speaker 2: But the planetary context is the catch.
Speaker 4: Exactly in exotic solvents at vastly different temperatures or crushing
Speaker 4: atmospheric pressures. The thermodynamics completely flip oh interesting In a
Speaker 4: liquid methane ocean. On Titan, it negative one hundred and
Speaker 4: seventy nine degrees. Oxygen is in a gas is a frozen,
Speaker 4: completely inert solid.
Speaker 2: Block, So it's completely useless.
Speaker 4: It is biologically useless. But alternative electronic acceptors, perhaps complex
Speaker 4: unstable hydrocarbon radicals or other dissolved exotic gases, might be
Speaker 4: vastly more efficient and chemically active in that specific, freezing,
Speaker 4: non polar context.
Speaker 2: It's all about matching the specific fuel to the specific
Speaker 2: planetary engine. You wouldn't put high octane jet fuel into
Speaker 2: a diesel tractor and expect it to run.
Speaker 4: That's a perfect analogy, and realizing this leads to a
Speaker 4: monumental civilization altering shift in how we view the universe.
Speaker 4: So if complex life can structurally arise without liquid water,
Speaker 4: and it can thermodynamically fuel itself without oxygen, the traditional
Speaker 4: habitable zone completely shatters its restrictive boundaries.
Speaker 2: You're talking about the classic Goldilock zone. Yes, the long
Speaker 2: standing astronomical idea that a planet has to be just
Speaker 2: the precise distance from its host star so that water
Speaker 2: is liquid on the surface, not too hot to boil
Speaker 2: and not too cold to freeze.
Speaker 4: Right, But if alternative exotic chemistries are viable, that earth
Speaker 4: centric concept becomes incredibly myopic and limiting. The potential habitable
Speaker 4: zone expands dramatically across the galaxy.
Speaker 2: It blows it wide open.
Speaker 4: Planetary bodies that astronomers have previously dismissed out of hand,
Speaker 4: places deemed far too cold, too violently hot, bathed in acid,
Speaker 4: or completely lacking an oxygen atmosphere, they suddenly become prime
Speaker 4: real estate for complex, thriving alien ecosystems.
Speaker 2: It literally turns the entire galaxy into a potential biological playground.
Speaker 2: It means that almost any geologically stable, energy rich environment,
Speaker 2: no matter how profoundly bizarre, could harbor something looking back
Speaker 2: at us.
Speaker 3: It's an inspiring thought.
Speaker 2: But that raises a massive logistical and technological problem. Well,
Speaker 2: it certainly does, because if the habitable zone is basically
Speaker 2: everywhere and life can be constructed out of nearly any chemistry,
Speaker 2: how do we actually search for things we've never seen?
Speaker 2: How do you program a multi billion dollar space telescope
Speaker 2: to detect a biological signature when you have absolutely no
Speaker 2: idea what the organism's metabolism looks like.
Speaker 4: This specific dilemma is the absolute crux of modern astrobiology,
Speaker 4: and it is actively forcing the scientific community to rewrite
Speaker 4: the textbooks on exoplanet hunting.
Speaker 2: Because right now, our current observational strategies are heavily, heavily
Speaker 2: biased toward finding Earth two point zero, right.
Speaker 3: Extremely biased.
Speaker 2: Walk me through the exact mechanics of how we look
Speaker 2: at a planet light years away right now.
Speaker 4: Primarily, astronomers hunt for what we call atmospheric biosignature gases.
Speaker 4: The technique is called transmission spectroscopy. Okay, We wait for
Speaker 4: a distant exoplanet to physically pass in front of its
Speaker 4: host star from our line of sight. As it transits
Speaker 4: the starlight filters through the planet's thin atmosphere before reaching
Speaker 4: our telescope.
Speaker 2: And the atmosphere changes the light.
Speaker 4: Exactly different chemical molecules absorb specific known wavelengths of light.
Speaker 4: By looking at the missing gaps in the light spectrum,
Speaker 4: we can determine exactly what gases are in that atmosphere.
Speaker 2: Like reading a barcode.
Speaker 3: Just like a bar code.
Speaker 4: Yeah, and we are specifically looking for the fingerprints of
Speaker 4: gases like oxygen ozone or methane in a state of
Speaker 4: drastic chemical disequilibrium.
Speaker 2: This equilibrium meaning those gases shouldn't naturally be there together
Speaker 2: in high quantities unless something like a massive biological ecosystem
Speaker 2: is actively and continuously pumping them out. Because oxygen is
Speaker 2: highly reactive, it quickly binds to rocks and disappears unless
Speaker 2: trees and algae keep making it.
Speaker 4: It is a very logical, highly pragmatic strategy based on
Speaker 4: what we know works. But recent complex photochemical computer models
Speaker 4: have thrown a massive, alarming wrench into this methodology.
Speaker 2: What did they find?
Speaker 4: We now understand that you can easily generate abiotic oxygen
Speaker 4: formed completely without any life present through the intense ultraviolet
Speaker 4: breakdown of water, vapor, or carbon dioxide in a dead
Speaker 4: planet's upper atmosphere.
Speaker 2: Oh wow, Which means oxygen alone could be a massive.
Speaker 4: False positive, a huge false positive.
Speaker 2: We could point a telescope at a planet detect a
Speaker 2: massive atmospheric oxygen signature through a massive global parade, thinking
Speaker 2: we found an alien forest, and it turns out it's
Speaker 2: just a dead rock being blasted by UV radiation.
Speaker 4: This is exactly why planetary context is absolutely critical. Astronomers
Speaker 4: cannot just search for one single magic gas. They have
Speaker 4: to analyze the entire atmospheric cocktail.
Speaker 2: They need the whole picture.
Speaker 4: Right, Is there water vapor present? Are there trace volcanic
Speaker 4: gases that corroborate a specific geological cycle? But more importantly,
Speaker 4: if we finally let go of the absolute rigid requirement
Speaker 4: for oxygen, we have to start aggressively scanning for entirely
Speaker 4: different alien chemical indicators.
Speaker 2: So what do those indicators look like? If we are
Speaker 2: pointing our telescopes to look for the weird non oxygen,
Speaker 2: acid loving or cold dwelling stuff, what is the chemical
Speaker 2: fingerprint of weird life.
Speaker 4: Well, we need to program our models to look for
Speaker 4: active ultra cycles and atmospheres. We need to look for
Speaker 4: strange gases like phosphene.
Speaker 2: Phosphene that caused a big stir recently, didn't.
Speaker 4: It It cause a massive uproar in the scientific community
Speaker 4: when anomalous amounts were potentially detected in the harsh clouds
Speaker 4: of Venus. We also need to search for exotic volatiles,
Speaker 4: complex heavy hydrocarbons, or unusual unnatural ratios of isotopes that
Speaker 4: can only realistically be explained by a biological metabolic sorting process,
Speaker 4: regardless of what exact chemical fuel that alien metabolism is
Speaker 4: actually running on.
Speaker 2: Let's bring this grand cosmic theory down to our immediate
Speaker 2: Solar system neighborhood. Where are the actual physical planetary targets
Speaker 2: we are looking at right now and how does acknowledging
Speaker 2: this weird alternative chemistry change how we view them?
Speaker 4: Within our own Solar system. The primary focus for the
Speaker 4: last two decades has heavily been on the ocean worlds,
Speaker 4: specifically Europa, a moon of Jupiter, and Enceladus, a small
Speaker 4: moon of.
Speaker 2: Saturn, both of which have water.
Speaker 4: Yes, both celestial bodies possess massive global oceans of liquid
Speaker 4: water completely locked beneath miles of solid ice.
Speaker 2: Crust, so they are the absolute classic follow the water targets.
Speaker 4: They remain spectacular high priority targets. The massive geysers erupting
Speaker 4: from the south pole of Enceladus have actually been flown
Speaker 4: through and physically sampled by.
Speaker 2: A spacecraft that still blows my mind.
Speaker 4: The data reveals they contain complex organic molecules, salts, and
Speaker 4: potent chemical energy sources like molecular hydrogen. There could absolutely
Speaker 4: be water based anaerobic life thriving down there in the dark,
Speaker 4: clustering around hydrothermal vents, just like they do at the
Speaker 4: bottom of Earth's socians.
Speaker 2: But that's still fundamentally water based life. Where do we
Speaker 2: look for the truly weird stuff in our.
Speaker 4: Backyard that brings us right back to Titan. Titan represents
Speaker 4: a phenomenal dual thread for astrobiology, a dual threat. Yes,
Speaker 4: it has those freezing liquid hydrocarbon lakes of methane and
Speaker 4: ethane on its surface, a completely alien, nonpolar solvent environment,
Speaker 4: but gravitational and radar models strongly suggest it also possesses
Speaker 4: a deep, sub terranean liquid water ocean trapped beneath its
Speaker 4: icy mantle weight. You could theoretically have two entirely different
Speaker 4: independent trees of life originating and evolving on the exact
Speaker 4: same moon. Oh my god, one water based, deep underground
Speaker 4: and one hydrocarbon based operating an extreme slow motion on
Speaker 4: the freezing surface.
Speaker 2: That is a staggering concept. Two separate origins of life
Speaker 2: on one tiny moon. And then, of course you have
Speaker 2: the acid clouds of Venus.
Speaker 4: The sulfuric acid droplets suspended in the Venusian cloud layer
Speaker 4: remain a massive, high priority target it's incredibly close to Earth,
Speaker 4: and if hardy aerial microbial life managed to adapt to
Speaker 4: hyperdicidic conditions as the planet's surface slowly boiled away billions
Speaker 4: of years ago, those clouds are exactly where we will
Speaker 4: find them.
Speaker 2: But exploring these extreme places right, really getting in there
Speaker 2: and touching the chemistry, it requires an entirely different engineering toolkit.
Speaker 2: We can't just orbit a camera and take pretty pictures anymore.
Speaker 2: Not if we want proof, we need massive thermal nuclear
Speaker 2: drills capable of melting through twenty miles of europen ice
Speaker 2: just to reach the water below. We need specialized chemically
Speaker 2: hardened aerial probes like robotic balloons or drones designed to
Speaker 2: float indefinitely in the corrosive clouds of Venus without just
Speaker 2: melting into slag.
Speaker 4: And for the exoplanets the world's many light years away,
Speaker 4: humanity is heavilyer lying on the incredible capabilities of the
Speaker 4: James Webspace Telescope.
Speaker 2: The JAWST is an absolute engineering marvel.
Speaker 3: It really is.
Speaker 4: Its instruments, particularly the Near Infrared spectrograph, have the unprecedented
Speaker 4: resolution to peer deep into the atmospheres of distant exoplanets
Speaker 4: and pick apart their minute chemical compositions.
Speaker 2: But it's only as good as the software.
Speaker 4: Right exactly, the incredibly complex data it returns to Earth
Speaker 4: is only as good as the interpretive models we use
Speaker 4: to read it. If astronomers only program the supercomputers to
Speaker 4: flag earth like water and oxygen bio signatures, we will
Speaker 4: actively ignore and miss the weird stuff. We must actively
Speaker 4: the data for non Earth signatures, just as aggressively.
Speaker 2: There is another fascinating angle to this search that completely
Speaker 2: bypasses the entire grueling chemical argument, and that is the
Speaker 2: search for extraterrestrial intelligence or SETI, and they're dedicated hunt
Speaker 2: for technosignatures.
Speaker 4: Technosignatures are intellectually fascinated because they are completely agnostic to
Speaker 4: the underlying messy biology of the alien life form.
Speaker 2: Because a highly focused laser beam sweeping across the galaxy
Speaker 2: is a laser beam, whether it was engineered by a squishy,
Speaker 2: water filled carbon monkey like us, or a slow moving,
Speaker 2: sand breathing silicon crystal living in a pool of acid,
Speaker 2: a dice and swarm harvesting a star. Massive atmospheric industrial pollution,
Speaker 2: artificial radio wave bursts. These artificial constructs mathematically stand out
Speaker 2: against the random natural background noise of the universe, regardless
Speaker 2: of the exotic biochemistry of the creature that built them.
Speaker 4: If they build physics based technology, we can detect the
Speaker 4: technology even if we cannot fathom their biology. It is
Speaker 4: a highly practical workaround.
Speaker 2: But let's assume for a moment that we aren't dealing
Speaker 2: with highly advanced laser wielding spacefaring civilizations. Let's assume we
Speaker 2: are simply looking at simple alien microbes trapped in the
Speaker 2: ice of Enceladus or weird slow motion hydrocarbon life on Titan.
Speaker 2: If we actively send physical probes into these environments or
Speaker 2: attempt to bring samples back, it raises a massive critical
Speaker 2: issue that space agencies absolutely have to address, and that
Speaker 2: is the severe ramification of biological.
Speaker 4: Contamination planetary protection. It sounds like a plot device from
Speaker 4: a science fiction thriller, but it is a very real,
Speaker 4: incredibly serious international protocol.
Speaker 2: Yeah, I've heard it, super strict.
Speaker 4: It is arguably the single most important ethical and scientific
Speaker 4: protocol in modern space exploration. Space agencies strictly divided into
Speaker 4: two main categories, forward contamination and backward contamination.
Speaker 2: Forward contamination is Earth life accidentally infecting an alien planet, right.
Speaker 4: Yes, Earth life is incredibly terrifyingly tenacious. We have discovered
Speaker 4: that the microscopic spores of certain bacteria like Dinococcus radiodurans
Speaker 4: can survive the absolute vacuum of space, withstand extreme cosmic
Speaker 4: radiation and endure radical temperature shifts.
Speaker 2: They just hitch a ride on our spacecraft.
Speaker 4: Exactly, if an international space agency crashes a poorly sterilized
Speaker 4: probe into the pristine subterranean ocean of Europa and a
Speaker 4: single hardy Earth microbe manages to survive the journey.
Speaker 2: It could find a nutrient rich ocean with zero competition.
Speaker 2: It could multiply exponentially take over the entire Europen ecosystem,
Speaker 2: and we would have effectively, irrevocably destroyed a native alien
Speaker 2: biosphere before we even got the chance to study how
Speaker 2: it worked.
Speaker 4: We'd become a devastating invasive species on a cosmic scale,
Speaker 4: which is exactly why probes are baked in radiation and
Speaker 4: assembled in extreme clean rooms.
Speaker 2: But wait, if alien life operates on a completely different,
Speaker 2: weird biochemical basis, say it naturally uses ammonia or sulfuric
Speaker 2: acid as a solvent, the dynamics of forward contamination become wildly,
Speaker 2: frighteningly unpredictable. Howso well would a hardy Earth microbe just
Speaker 2: dissolve and die instantly in the toxic ammonia ocean, or
Speaker 2: would it somehow rapidly mutate, adapt, and completely outcompete the
Speaker 2: much slower metabolizing native life.
Speaker 4: We simply lack the data to know. It's a massive unknown.
Speaker 2: And then there is the arguably scarier prospect of backward
Speaker 2: contamination bringing the weird alien chemistry back to Earth.
Speaker 4: Right if a future mission successfully retrieves a physical sample
Speaker 4: from Titan's freezing methane lakes, or scoops up some mists
Speaker 4: from the Venusian clouds and brings it back into a
Speaker 4: laboratory on Earth, how do we physically protect our biosphere
Speaker 4: from completely alien chemistries we barely understand.
Speaker 2: I mean, an organism evolutionarily built to thrive and concentrate
Speaker 2: sulphuric acid might find the warm, wet moisture and a
Speaker 2: human lung to be an incredibly volatile, destructive environment.
Speaker 4: Or worse, it might find our specific carbon based biology
Speaker 4: to be a massive abundant source of entirely unprotected chemical energy.
Speaker 2: It is the ultimate Andromeda strained scenario. But with the
Speaker 2: terrifying added twist that the alien pathogen doesn't even share
Speaker 2: our basic DNA structure. You cannot easily manufacture a vaccine
Speaker 2: or an antibody for a life form that utilizes a
Speaker 2: completely alien, unrecognizable catalog of molecules to function.
Speaker 4: The rigorous, multi layered sterilization and bioquarantine protocols required for
Speaker 4: the planned sample return missions over the next decade are
Speaker 4: completely unprecedented in human history. The biological and chemical stakes
Speaker 4: are quite literally planetary.
Speaker 2: This has been an incredibly massive journey into the deep
Speaker 2: weeds of chemistry, biology, and the sheer scale of the cosmos.
Speaker 2: Let's try to pull all these complex threads together and
Speaker 2: synthesize what this means. Because humanity is currently sitting exactly
Speaker 2: between two radically different, philosophically massive views of the universe. Yes,
Speaker 2: we are on one side. You have the highly restrictive
Speaker 2: rare Earth hypothesis right.
Speaker 4: The rare Earth hypothesis suggests that the highly specific combination
Speaker 4: of carbon, liquid water, and abundant oxygen is the only realistic,
Speaker 4: mathematically probable way in the universe to achieve biological complexity.
Speaker 2: So we're just incredibly lucky exactly.
Speaker 4: It argues that because that incredibly specific chemical combination, along
Speaker 4: with a stable, long lived star and a protective gas
Speaker 4: giant like Jupiter to sweep away asteroids, is so incredibly rare,
Speaker 4: we are essentially alone, or at the very least complex
Speaker 4: thinking life is a one in a billion cosmic anomaly.
Speaker 2: It makes human existence incredibly fragile and incredibly special. But
Speaker 2: on the exact opposite side of that scientific tension, you
Speaker 2: have this vibrant vision of a chemically wild, untamed, chemically
Speaker 2: diverse cosmos where life simply, stubbornly finds a way.
Speaker 4: A universe where biology sparks and rolling acid clouds, thrives
Speaker 4: in freezing methane lakes, and slowly patiently builds crystalline structures
Speaker 4: in the absolute dark.
Speaker 2: If that second chemically diverse view proves to be true,
Speaker 2: if our probes definitively discover that complex life can and
Speaker 2: does exist without a drop of water or a breath
Speaker 2: of oxygen, it would trigger the greatest scientific paradigm shift
Speaker 2: in human history.
Speaker 4: Without a doubt, it would instantly fundamentally revolutionize our foundational
Speaker 4: understanding of biology, of thermodynamic chemistry, and of our own
Speaker 4: place in the universe.
Speaker 2: It would strongly imply that the emergence of life is
Speaker 2: not a fragile, lucky fluke, but a highly robust, nearly
Speaker 2: inevitable consequence of complex chemistry playing out across the cosmos.
Speaker 4: It is a deeply humbling thought, and humility is really
Speaker 4: what this entire scientific endeavor comes down to. The universe
Speaker 4: is under absolutely no obligation to make alien life familiar to.
Speaker 2: Us, no obligation at all.
Speaker 4: It is under no obligation to make it easy to
Speaker 4: detect with our telescopes, or even comprehensible to our human brains.
Speaker 4: Science thrives exclusively on humility and the willingness to be wrong.
Speaker 2: Because the exact moment we assume we know all the
Speaker 2: universal rules of biology.
Speaker 4: We guarantee that we will miss the greatest discoveries waiting
Speaker 4: in the dark. The next decade of space exploration, the
Speaker 4: nuclear ice drills, the acid resistant rovers, the new generation
Speaker 4: of deep space telescopes isn't just about cataloging new rocks
Speaker 4: or finding simple aliens. It is a quest to fundamentally
Speaker 4: redefine the very word alive.
Speaker 2: We are standing right on the edge of a conceptual cliff,
Speaker 2: and we're finally starting to realize that the ground below
Speaker 2: us is vastly wider and vastly stranger than we ever
Speaker 2: dared to imagine.
Speaker 4: It's an exciting time to be looking up, it really is.
Speaker 2: So as we wrap up this exploration into the bizarre
Speaker 2: chemistry of the cosmos, I want to leave you with
Speaker 2: one final lingering question. Tom all Over, we've talked extensively
Speaker 2: about how our current instruments, our massive telescopes, and our
Speaker 2: planetary models have been so heavily, rigidly tuned to look
Speaker 2: for Earth like life. We've been aggressively searching for water,
Speaker 2: hunting for oxygen, looking strictly under that one specific street light.
Speaker 2: What if, just what if our telescopes have already detected
Speaker 2: the faint, strange atmospheric signatures of a bizarre, non water,
Speaker 2: non oxygen ecosystem out there in the deep black, but
Speaker 2: because the chemical data didn't perfectly match the specific biological
Speaker 2: fingerprints we were taught to look for, we completely dismissed it.
Speaker 2: What if we threw out the greatest discovery in human history,
Speaker 2: labeling it as instrument error or geological noise or just
Speaker 2: a glitch in the data. Are the alien ecosystems we've
Speaker 2: spent decades searching for already sitting right there in our
Speaker 2: massive server hard drives, just waiting for us to expand
Speaker 2: our imagination enough to finally see them.