What If Alien Life Were Silicon-Based?

čas přidán 20. 03. 2023
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Life as we know it is carbon-based, but does it have to be this way? There’s another element on the periodic table that shares some of the key properties of carbon but is far more abundant on most planets. I’m talking about silicon. So is there silicon-based life out there?

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What If Alien Life Were Silicon-Based?


  • For clarity: estimates for diatom oxygen production mentioned at 13:36 range from 20%-50% on an annual basis. If there’s any specialists in the audience who could provide greater clarity about diatoms and oxygen production, please reply to this comment!

    • Life may exist in different form at different places.. ✌️

    • Can you tell me when Starfield comes out?

    • @Joe Stitz speak for yourself I put piles of salt on all my food but always have low sodium I’ve also been dying for 11 years tho

  • This reminds me of a rare event in the game Stellaris where you find a cavern full of buildings and extremely detailed statues deep within a planet. After researching deeper, turns out the civilization wasn't long extinct, but instead was Si based, and when you broke through the cavern wall, the chamber flooded the area with O2, it turned them all into stone. Kinda scifi and quite a grim discovery, but a pretty cool storyline!

    • Can SOMEONE link me a video or picture of this

    • @The Pip bro my brother had an alien/space dream last night too .. weird

    • I read this comment of yours quite a while ago but apparently it really stuck with me since last night I had a nightmare about this exact scenario. Well, in the nightmare I’d opened a portal to an alien planet but same difference. When I got there I found all the life there was petrified and I realized it was because they were silicon based and the oxygen that came through the portal did that to them. Also I was a crewmember on the Starship Enterprise and Captain Picard was really upset with me.

    • @Christopher Lawless well it depends if the atmosphere is high if it isn't silicon based life can survive on mountains

    • That’s actually genius

  • I am now convinced that the Sandworms from Dune are silicon-based. Their aversion to water and huge production of sand seem to align with being silicon based.

    • If you squish one, and smear some of the guts along the edge of your bath, shower partition, or windows, it does very well at preventing water ingress.

    • And IL remind everyone that the mad scientist tilaxu spent the better half of a millennium trying to cut the sand trout and organics all together from spice production and failed miserably.

    • 1) the sand trout does not make sand, the sand is created by natural dune formations due to all the water in the once oceanic world of arrakis being held underground in a large aquafers by the sand trout life cycle. 2) only the adult Sand worm is averse to water. The sand trout (the larval stage)require it to reproduce. So does it's fungal stage. 3) they are most certainly carbon based. We know for a fact that the sand trout, and thus their final stage worm are in a few ways compatible with humans. The quizrakt haderach was able to use bennigeseret hormone and chemistry control to slowly merge with an entire brood of live sand trout, becoming the *Worm-God emperor of Arakkis* I find this to be an entirely unlikely thing had they been silicon based life. In the books he is very clear about exactly what was necessary to merge and it was essentially 2 things. 1) controlling the water that touched and dissolved into the sand trout 2) controlling the inherent spice the trout began to pump Into his blood. He controlled these two chemical interactions and allowed for a smooth transition into half man half worm. After he was never again able to touch water without it burning him. He couldn't even touch another human. Furthermore On Top of all of this, later on after the death of God emperor Leto II they create a "super worm" that lives on the new water coated surface of arrakis in the oceans. Creating a hyper super spice. This proves that the water sensitivity was never something that fundamental to the worms but rather likely a volatile chemical inherent to spice production....

    • @Driizzy I’m not saying that’s why Arrakis is dry, but there’s a number of references to sandworms creating Arrakis’ sand.

    • @Ben Ducker yeah but the adult ones react very poorly towards it

  • One thing not many people talk about is that under extreme pressure (routinely found deep within gas giants), nitrogen can form chains that are even more diverse than carbon chains.

    • Everything is possible, even in deep cold dark ocean, there is life on it, but they can only life there, in their own comfort zone...

    • ​@matthew bai You mean like life 7 miles down below our ocean? Imagine the pressure there?

    • @matthew bai why should it not? why could life not adapt to that?

    • Never knew that. Of course, if they depend on extreme pressure, such life forms could never escape their planet. On the other hand, we haven't done much better. And if they're living in Jupiter, they've got a lot of room to roam around in.

    • @matthew bai for all we know right now carbon based life could be the outlier in the universe.

  • I think the key phrase here is when you said “if nature has a choice”. If nature is a force that tries to fit itself into any nook and cranny it can fit into, then it will, as a famous fictional character said “find a way”. If silicon is its best option, it’s going to use silicon, no matter how much it has to work around issues.

    • ​@Mini Whiffy3 are you saying you don't recognize the quote? First Jurassic Park movie, the scientist played by Jeff Goldblum says that, early in the movie.

    • @Pawel lk Woah… this blew my mind.

    • I highly doubt silicon would be the best option. there's a reason most of the strongest material known to man has carbon in it. even the ultra-strong silicon stuff has carbon. life needs this strong building block called carbon to be durable. silicon life might be able to exist, but carbon just makes a lot more sense to me.

    • @Ginsederp Derpy the problem with high efficiency lies in stability and how being able to attain maximum efficiency can depletes your environment ressources too fast for the biome to recover and pose the threat for the long term presence of the specy. if you had a specy that could consume CO2 and reproduce incredibly fast with no limitation, in a closed system like earth is, this specy would face extinction as fast.

    • And yet multicellular organisms, especially myself, seem far from the most efficient and “best way” to accomplish life. Reproduction? Whatever the meaning of life is. The vast and complex biological systems and ecosystems that are present all over this planet never struck me as the “best” way to accomplish something, because they add so much apparent needless complexity.

  • I think an underrated aspect of carbon chemistry is the fact that you need really exoteric conditions to get a carbon making more than 4 bonds. That's useful because a lot of how organic chemistry works relies on the consestency of 1 bond being received meaning another one is broken, which is especially important for enzymes. The fact that silicon can much more easily be coaxed into making more than 4 bonds make these chains either far more complex or far mor limited. Also, silicon can hold a charge much better which has its ups and downs

    • More like has its positives and negatives, amirite?

    • @Uncle Al Schwartzhello can I hav a chat with you

    • Esoteric? Sn2 displacements go through five-coordinate carbon.Six cordinate carbon, and no metals involved, DOI 10.1002/anie.201608795; Pyramidal C6(CH3)6(2+) "8^>)

  • This is the best biology lesson I have ever seen and it's from a physicist not a biologist or chemist. I think the explanation of the different pathways of biology makes it more understandable. Looking at the idea from multiple facets makes it clearer. Fine work, sir.

    • I couldn't agree more, Marcus! 🤩😊 PBS Space Time is the best channel to learn about the science behind life in the universe. Bravo!

    • I'm glad that the explanation of the different pathways of biology has been helpful

  • “It’s … sand. It’s coarse and rough. And it gets everywhere” A man of culture indeed.

    • _"it gets everywhere"_, as many honeymoon holidaymakers can attest ;-)

    • "a man of culture" 🤓

    • @nictibbetts not from clone wars, stay in your lane hummie

    • @Nick Tibbits it doesn’t. But saying a line from Attack of the Clones does.

    • @Based The youtube comments police is here folks, hide your comments!

  • Great video, but the molecule shown at 2:25 was not nitroglycerin but tri nitro toluene (TNT). Also the lattice shown for metallic bonds at 3:53 applies to ionic bonds as well. Small points but otherwise really great stuff!

    • @Tangobaldy I did

    • I think at 3:53 the graphic for ionic bond and metallic bond is actually mixed up. Because the graphic for ionic bond clearly shows electron travelling from one atom to another (which describes the sea of electrons of metallic bond), and there is positive and negative charge in the graphic for ionic bond, which describes lattice of cations and anions. The graphics should be swapped.

    • Damn I studied chemistry and I didn't notice the mistake😭

    • I was too busy fulminating to notice the second mistake Hg(CNO)2

    • @Seth Yellin Yeah, it's an old Simpsons reference

  • Excellent video! Thank you for choosing to use your talents to give the gift of understanding of otherwise out of reach subject matter for most people. Even I, as a scientist, appreciate your ability to deliver complex topics into a digestible form, so effortlessly. Bravo.

    • He said so much yet nothing at the same time. The average viewer like myself isn’t clicking on this video to hear a bunch of science jargon mumbo jumbo that is going to be forgotten in 30 seconds with the next wave of over-information. I was actually falling asleep. He could’ve saved himself and us so much time by just opening the video with the summary at 12:12. He only answered the title of the video for about 2 minutes .

    • 👆Your message are useful but follow the easy way of making income Tell Andrei jikh i referred you👆✍️

  • best summary of the issue I found so far, thanks for sharing. As a sci-fi writer I find time and time again that Carbon based is easiest to do, I'll sometime throw in some silicone for shells instead of calcium for various reasons, but insides always end up with Carbon cuz chemistry.

    • What I find interesting is evolution with more or less the same chemistry but in very different ratios, like a planet with very high carbon content.

  • Imagine, though, feathers grown by a silicon based life form. They might be so incredible! Like frost crystals on glass, or as reflective/refractive as diamond!

    • @Tom Quixote fancy seeing you here hermano

    • @Tom Quixote 😜 We have three peacocks, two peahens, some quail, and a very spoiled Black East Indies house duck (she lives in the house with us) We are familiar with bird feathers. The peafowl feathers ARE actually brown and gray, and microcrystalline structures on the feathers refract light in amazing ways. Imagine if the feathers were silicon based, and therefore inherently crystalline.

    • While feathers grown by carbon-based birds are all black and can be used to write with.. no, wait.

  • I loved it! Finally understood a lot more about this entire question. AND I loved that despite all examples we as viewers were encouraged to keep an open mind and not allow ourselves to become too self-centric here. Thank you very much :0)

  • This is an exceptional video. I studied biochemistry and the way you built up an understanding of what it takes for life to happen while making it accessible to the general public was just fantastic. Love this channel.

    • Electrician here, and while I've always taken up learning in my free time and I'm still astonished at how much this channel has taken that approach towards making subjects (that I find fascinating already) digestible and appealing for audiences that might not otherwise be exposed and attracted to them. I've watched this channel for years now, and I can honestly attribute my recreational interest and fascination with these kinds of topics to PBS Space Time and Matt O'Dowd. Thank you all for turning this adult into a giddy and excited child for concepts far out his normal realm of exposure and occasionally comprehension.

    • Not a chemist and I was actually bad with chemistry in school thanks to a particularly bad teacher, but I agree. Even though I don't know the first thing about biochemistry, the episode still managed to dumb the subject down enough for me to at least understand the basic concepts behind it.

    • It beats the pants off the Sauce of V.

    • I actually understood this episode!

    • 'ey! A fellow Hololive fan.

  • One interesting variation is the horseshoe crabs and other crustaceans (lobster?) which use copper instead or iron to carry oxygen around their bodies. Aliens are more likely to be little blue men rather than green. This could hint that if silicon-based life had ever evolved, some could have survived, maybe in critters like the flying spaghetti monster.

  • Thank you for this video, I have always been curious about the possibility of silicon based life. Also I appreciate showing Spire as an example. I'm glad people still remember the characters from Metroid Prime Hunters.

    • I still got my copy of it

    • One of the greatest games ever made.

  • I feel like a great way to follow up on this could be a similar video on why water is so useful for life. I have a vague notion that it has something to do with it's place in the pH scale and how that lets a lot of different things dissolve in it, but is there any other chemical that could be a solvent for complex molecules?

    • @Annelie Skoog that does help some. I have to wonder now, whether there are any other polar liquids that could act similarly. Seems like any polar liquid should be able to dissolve the same molecules

    • Not pH so much as the molecule polarity: a polar molecule has a negative end and a positive end. The water molecule is somewhat V shaped; hydrogens at the two upper ends of the V, and oxygen at the bottom of the V. The V shape allows the slight difference in charge between the top and bottom: the top is slightly positive and the bottom slightly negative. This is the key to water's strange and unique properties. Water is an excellent solvent because it attracts both positively-charged and negatively-charged ions, since it is polar. In addition, water molecules attract each other's differently charged ends. Positive attracts negative and vice versa. Think of it as though the water molecules are holding on to each other. You also asked about complex molecules. Whether they dissolve in water depends on their polarity. Larger molecules that are not polar do not dissolve well in water because they are squeezed out of solution by the attraction among the water molecules. Another way of saying that is that the attraction between the water molecules is greater than the attraction between the water molecules and the complex non-water molecule. Hope that helped and I do agree it would be great to see a video on the crazy properties of water!

    • It's polarity means that one side of the molecule it's slightly positive and the other slightly negative.

  • This video perfectly addresses audiences with a high school chemistry education! Made it very easy to understand, thanks!

    • Middle school, I would say. You can understand all of this with 8th grade knowledge.

  • I remember that roughly 15 years ago, there was bacteria found in the cave systems of the Roraima Tepui which appeared to feed on the quartz walls- has there been any follow up analysis of that bacterium?

  • The reason why arsenic is toxic is actually fascinating, I’ve never heard that anywhere before and I took a lot of science courses and been watching channels like this for a large portion of my life now

    • @Benny they didn’t simply because it contradicts the As toxicity argument, which is extremely wrong :(

    • @Dominik Kamrowski I was surprised they didn't mention that bacteria discovery at Mono Lake, I remember that news story

    • Re-paste of a part of my longer comment: The second major flaw, probably the most shocking one, is your explanation of arsenic toxicity. I call upon all the gods, where did you guys get it from? On top of the comments list I see someone thanking you for the explanation and I feel sorry for that person and all the others who believed. Arsenic toxicity is directly related to its high affinity for thiol groups (As(III) to -SH groups) in amino acids, proteins (enzymes!) and enzyme cofactors. Arsenic is toxic in that (+III), most common state where it doesn’t event resemble phosphate groups. Its disruptive influence on the processes (ATP, so cells’ energy production on top of all) is the most significant factor, not ‘accidental’ use by cells while building necessary molecules because of its similarity to phosphorus. Please, next time do some research, because you have used a real phenomenon (chemical similarity (not identity!) of As to P because of being in the same group in the periodic table) to explain a real phenomenon (arsenic high toxicity), while making such a cardinal mistake. In the same movie you talk so much about analogous carbon and silicon similarities, but fortunately I have never heard about sand’s (mainly silica) toxicity caused by chemical similarity of silicon and carbon. All the people laying on the beaches remain safe… What a relief. To add something more, silica is a widely used food additive. Are we all in danger? Will we become silicon-based aliens in the future? Fortunately not, because your explanation is just fanciful. To add something extra, a few years ago we have discovered some bacteria species with arsenic bult (instead of phosphorus) into its nucleic acid. Guess what - that bacteria seems to be completely fine, its core molecule is not breaking apart spontaneously.

  • Could you potentially create an Adenine-Triphosphate equivalent using Silicon that could create energy? Maybe not for life persay, but maybe some cool futuristic robots!

    • @Bryce J Yes

    • @Aaron Davis No

    • @werr kowalski Thank you for this informative response. I'm definitely no biochemist, but I would think that the Silicon would be stabilized with the same connections to Oxygen, Hydrogen, Nitrogen, and Phosphate molecules like its Carbon equivalent. But, I suppose you're right, it's all pointless without a protein equivalent to receive that energy release.

    • ATP is hydrolised to release energy, and silicon compounds are unstable in water. If you could get past that issue then maybe, but ultimately it would be irrelevant. There are other molecules transporting energy than the ATP, NADH being the main one and probably a few other biological curiosities. But all of this is irrelevant because the basis for life are proteins, you can come up with speculative ways to transport energy, but there is no life without proteins, and it is impossible to build silicon based protein analogues.

  • This is something I have always wondered! people get too traped to what we know here on Earth, and forget all possibilities out there, including silicon

    • Same! I think about that a lot when people talk about what exactly is considered life, and what specific requirements a planet must have to support life I’d think “that’s life on earth though, the only life we know. What if it’s dust based or rock based or something weird Iike that” I’m not good at science so I didn’t immediately think “silicone” but it’s such an interesting example It’d be honestly so cool if we find non carbon based life, it’d change everything in science

  • Best episode ever. Why Life Is The Way It Is broken down in such a... superb way. And the Sci-Fi references were very funny! (Sand really does get everywhere.)

  • I love that at 11:38 he makes a star wars reference. The meta reference is impressive. Most impressive.

  • This is so cool I keep going back to this video all the time. Although Si in particular is hard to imagine as a block of life, the topic itself is very interesting.

  • Thank you, Matt, for all you do for PBS Space Time! At 83 years old I'm too old to do a lot of things, but never too old to listen and learn!! You're the best!

    • I'm so glad you enjoy watching PBS Space Time and learning from Matt! 🤗 It's always inspiring to see someone as passionate as you, Marilyn.

    • @sebastienne sp damn you both are lifegoals

    • I’m thankful you enjoyed the video

    • @Elliana Dailey that's right

    • Hey! I'm rapidly approaching 70. (Eek, how did that happen!!?) But, I cannot imagine a point whereby I lay down, and sigh... "Oh, I've learned enough"

  • Hey Matt, Love your work on Space-Time which got me to support your movie on Indiegogo which I sincerely hope will meet your expectations and more. We're only carbon-based humans and not silicon-based zero mistakes makings robots so you definitely don't have to fact check every joke.. and titan or triton whatever hehe that's not the point. Also, a giant THANK YOU for you and the team for all the hard work of making good solid science so accesible!

  • Interesting concept! It stirred up a few thoughts: - perhaps silicon's reactivity with building blocks can be blunted in Si scaffolding by combination with carbon (or another element)? Non carbon based biochemistry doesn't necessarily mean it's thoroughly excluded from the chemistry after all. - concerns regarding reactivity with oxygen may not be so worrying if we imagine alternate environments in space with different proportions of building blocks. - i actually can imagine microbial life forms who slowly metabolize energy from silicon based biochemistry, with SiO2 biproducts being systematically expelled via tiny vacuoles. Makes you wonder what sort of stuff could be hiding in plain sight on places like Titan Oh, and loved the Anakin Skywalker reference you tossed in there, btw 😂

  • It's really hard for me to imagine the enzyme or enzymatic parallel to our physiology. Because carbon sugars and enzymes are so compatible, there would theoretically have to be some zipper and unzipper of silicate chemicals, which makes me think they'd be much more sensitive to environmental pH than we are.

  • The critters we find on other planets, biological machines built from efficiency, will probably be terrifying. I think we will meet similar looking aliens, but every once in a while find a bug pit that is the stuff of horrors.

  • I was hoping you'd mention the Horta of Star Trek too 🖖😊 Also, I'm fact-checking for a short story I'm writing. Assuming there were silicon-based lifeforms, what kind of atmosphere would they require? Could they survive for short periods in an oxygen-nitrogen atmosphere? What would they eat? Thanks!

    • 🤓🤓🤓

    • ​@john tracy and exhale rock, or sand, too...

    • I would imagine that silicon based lifeforms would eat rock.

    • He mentioned methane and sulphuric acid as the kind of molecular environment suitable for silicon-based life. And silicon bonds to oxygen too readily so it would prevent bonding with other elements/molecules. Imagine a smelly, acidic hellscape. That's your silicon homeworld.

  • When I was a kid, learning this stuff felt like a chore in school. Now it's just really interesting. I'm glad things like this channel exist so I can still learn even though I missed my chance in school.

    • @Bipolar Mind Droppings Well, whether you learn from youtube videos is debatable. But if you take some other examples, then the argument that "work = no fun" doesn't hold. Many people self-learn programming these days. The process starts with messing around with software (perhaps a game), modding it, diving into documentation to do the thing you want, then learning actual best practices used in the professional industry. That example would be undeniably "work" as you've defined it, but anyone who does that by themselves will likely tell you that the experience is a lot more fun than taking a high school course. After all, the desire to create with their own hands is what drove them to do all that. Similar stories can be found with people self-teaching music, art, history, etc. I don't think physics would be any different. Some of us watch the video and never do anything more, but some will watch the video and go on to learn deeper things by themselves. The only thing I'm quite sure of is that most modern school systems are inadequate at inspiring the desire to learn in this way.

    • @Bipolar Mind Droppings I'd be willing to argue that learning concepts is more useful for the average person than learning how to put it into action. Your average person would never need to know atomic weights, but having trivia knowledge is priceless.

    • Some kids (me) had to worry about holes in there floors, family conflict till 12 am or wee hours of morning, health, diet, hygiene over just the simple 20$ hs course fees to be able to control educational path and possibilities. Until the adult freedom and exposure helped. But other than what my parents believed (carpenter or mecahnic) I wasn't getting any chance to succefuly complete dedicated subjects that interest me. Worse was the school counselors convincing me that my issues were small and crying over spilled milk ( implicating it's my fault I have to feel like I need to ditch school for employment and not my "caretakers"fault.)

    • I think this is more entertainment than education. As someone else has pointed out, you don't need to memorise the content here, so it requires a lot less effort.

  • Wonderful call back to one of your earliest videos (on colonising Venus) that still holds a special place in my heart.

  • One interesting extension of this that I wonder about is pressure. All of the chemistry discussed assumes nearish to atmospheric pressures, but if you go pressures comparable to deep inside planetary bodies that chemistry changes dramatically!

  • I wonder if it's possible to use A.I. in a simulation to construct a theoretical organism based on Si. There would have to be very specific conditions it operates under, such as an environment where Si-based biochemistry can thrive.

  • Thanks Matt for the correction on the wings of birds and bats, the CS-tv community may now rest peacefully knowing that such serious errors have been retracted.

  • As a chemist your discussion of silicon chemistry was better than I was expecting, especially after you flubbed "nitroglycerine" (1,2,3-trinitroxypropane) by showing the structure of TNT (2,4,6-trinitrotoluene).

  • "Life is an ongoing chemical reaction" is perhaps one of the cooler scientific descriptions of life that I have heard in a while.

    • @Mad Scientific The sky is green twice a day en.wikipedia.org/wiki/Green_flash

    • @Tim Perfetto What if the sky were green? Lol

    • @Mad Scientific What if alien life were silicon based?

    • @Cypherusuh *electrochemical

    • You're a self aware self improving chemical reaction capable of making more that all do the same thing. That said this is no kind of new revelation.

  • This seems to be a more likely scenario than finding biological life forms.

  • I am also a fan of the Goldilocks theory of the Great Filter. Like the lottery, having many smaller factors actually decreases the odds of success rather than one giant obstacle.

  • Thanks for the book recommendation by Penrose. Think I've seen it a few times and have been tempted to pick it up, but I could tell it'd be a pretty heavy read. That's right, he's a Platonist. Can't recall which book I was reading about Godel, but I recall the author noting that Gs idea about mathematical reality was a bit out of fashion. In any case, having experienced synethesia a few times with both sound and numbers...had to try to calculate a number thru division and recall the sum being something with a row of 13s and I could "see" the answer into a narrow horizon and the numbers were colored this bright yellow-orange. This didn't necessarily cause me to posit a theory of forms or anything, but the idea or belief (especially if held by people who work with numbers and are much more intelligent than I) seems plausible.

  • This concept is very interesting, because there are indeed many possibilities from every possibility that exists. this might be one of the supporters that the Artificial intelligence that we are making may be natural intelligence, just like what we have now

  • Somewhere in another galaxy, scientists ask: “could there be someone out there with life based on carbon?”

  • This topic has been done to death by other CS-tvrs, but PBS Space Time has really shown how to properly address this topic, bravo!

    • @Yttrx Stein Yur latest reply didn't make it past the censors baby boy. Try another tantrum maybe a bit toned down?

    • @Yttrx Stein You kidding me? Bonehead to Spock "Now you're telling fantasies. Silicon based life is impossible". Devil in the Dark was 25th episode of Season 1. There were events in the 24 episodes before it that broke laws of physics and chemistry with the incompetent one there to witness. Kelly got the worst lines of any major character on the show, other than Sulu (but he really isn't a major char). All in all, while only a few episodes are total disasters scriptwise (That Which Survives, Obsession), not one of the rest didn't have moments of rather illogical, terribly written script ..

    • @Rossi Gastone I did not know that and googled it and found out it is a part of the Flat Earth theory. It is fascinating how crazy people can be.

    • I prefer the "There are no forests on Earth" version.

    • Isaac Arthur's version was just as good

  • For clarity, the xenomorph reference to it being a silicate-based lifeform must be based on a single sentence uttered by Ash in the very first movie. He however actually says that the xenomorph is replacing parts of its body with silicate matter >when it hibernates

  • In my opinion the first step to finding out alien life is to look for life that is very similar to us because otherwise we would struggle greatly to comprehend it. After that we move on to more, exotic, you could say life. From other planets depending on the material they are made could sprout things we would never understand with our little ball we live on. So far when I look at other media of alien life it is always connected in some way to how we were made, being humanoid, being made of cells, requiring water, etc. So if we are to spark that little heads of our up about what could be up there we need to find it first. Or the alternative is that the universe is dead and we are the only ones in a finite universe.

  • I asked kind of a similar question to a very prominent scientist in our country (Dr Yash Pal), when I was in highschools. But my focus was on why we are looking for 'water' as a possible sign for life and why can't an alien life form be dependent on something other than water. He went on to give a really long winded answer which basically boils down to....cosmochemical abundance. He thought for any lifeform to be successful, the best would be for it to evolve to depend on what's the most abundant element and that's Hydrogen. So following on that train of thought, maybe we shouldn't be looking the base of our life as just 'carbon' based and instead as 'Hydrocarbon' based and Silicon's preference for oxygen over hydrogen might actually be the reason why life didn't form around silicates. Maybe having a very strong preference to choose an element that's abundance is just 1% in the Universe over the vastly more abundant Hydrogen which is about 73.9% in the Universe, might have become the roadblock to being the unsuitable for being a base of lifeform. Since flourishing of life is directly correlated to abundance of resource, the same principle might have possibly been applied to the very molecular level

  • What about an exoshell type being in a high pressure low oxygen environment? High pressure could make for other liquid options, the shell could allow a different processing of the byproducts of silica based life.

  • I love how elements are understanding them selves

  • As a chemist I first thought "Oh no, not this again". But you made really really good video explaining why Si based life is highly unlikely. Good job!

    • @ToxicQueen Did you not watch the video? He basically explains why Silicon could be considered as a possible alternative to carbon to form life. He then spends even longer explaining why it isn't any good. You have heard the phrase, as usful as a chocolate fire guard before? Yes whilst you could make one it just won't survive very long as a fire guard. This isn't about imagination and what you wish for. Its about how chemisty works the same way universally. What doesn't work here basically wont work anywhere else. That might sound negative but in the light of facts would you still consider that God exists? If we consider that life could be rare and limited to Earth (As we have yet to find evidence that life is abundant) in this Galaxy it makes the chances of any life evolving elsewhere extremely rare stacking the odds against it by using less than ideal chemisty then makes those chances diminishingly small.

    • @Lamster 66 except you guys are under the a very heavy and biased assumption other life HAS to be like life on earth and has to follow by our ways of existing

    • You and your limited closed mind can’t even comprehend what could exist out in the ever expanding universe to say something is highly unlikely

    • @Dizzy The Fish Considering any complex chemistry and networks as alive is a poor way of classifying life. I'd actually argue that much of what we consider 'alive' today actually isn't alive and how some people still attempt to empathize with such things is weird. If it isn't capable of self awareness and cognitive experience of the world that can react to conditions it is exposed to by conscious control of self then it is just a complex chemical reaction with similar chemistry to our own. It might as well be as alive to us as a rock. Plants in my opinion are not alive and have no conscious experience or sense of self and can not feel anything as everything they do is determined by genetic instructions that plants have in far greater amounts then animals do. Probably best to stick to empathizing with organisms that have brains with sensory organs that can control action via some nervous system and assuming consciousness forms in any other system, even ai without complete physical emulation of those kinds of systems and incentives to act such as pain and pleasure, is a matter of faith.

    • @M. dickerson Thanks for pointing that out. Even top level astronomers that I know totally dismiss Si as possible in this regard.

  • Great job explaining complex science and chemistry to a non-scientist in a fairly easy to understand way.

  • This is an excellent breakdown of the periodic table and why different atoms are unsuitable for building the structures of Life. Also, I watched the following video breaking down the motion of Earth, the Sun, and the Solar system, and it was equally thorough, understandable, and sound. I guess what I'm saying is PBS Spacetime is in a streak of excellent videos and I give all due praise for that. Keep it up Dr. O'Dowd et al.

  • Thank you so much for this beautiful video. You mentioned non-water rich planetary system to be unusual. But is it really the case? I mean which is more abundant? Water based planetary system or hydrocarbon/acid based planetary system (in term of abundance of available solvent)

  • In Destiny, the Vex are silica-based, living within the data transferred between the Silica exoskeletons of radiolarian microbes (that's at least how I interpreted it). They live in robotic exoskeletons, and the compartment which encases the radiolaria is their "weak point".

  • Would it be possible for silicone based life to form under extreme amounts of pressure where there is alkaline water and methane vents? Like deep deep in the ocean?

  • Please keep up your great sense of humor! It's sad that some will use it as an opportunity to make you seem like you don't know what you're talking about and to elevate themselves in their own minds.

  • I feel as if this video came at such a perfect time. Just had a conversation with a coworker (we're both junior chemists) about this topic! Interesting insight

  • Couldn't a sentient AI potentially be considered silicon based life?

  • Amazing information!! Perfectly put together and explained so that everyone can understand

  • I’ve read in many places that boron is a pretty good candidate for non carbon based life. The reasoning is boron can form chains in a similar manner to carbon. But I also read in an essay by Asimov in the end carbon is the only candidate.

  • “It’s … sand. It’s coarse and rough. And it gets everywhere” 😂 A man of culture indeed.

  • When you said silicon-based life forms would need to poop out a lot of glass beads or something... It reminded me of the "blueberries" NASA rovers often see in the Martian soil. Perhaps there were or still are silicon-based life forms on Mars?

  • I've read this one book called Coming of Age in the Milky Way and it astounded me with one of its chapters discussing life's origin. It talked in great detail about what we can consider "life" by contrasting metabolism and reproduction. Apparently, one of the theories proposes that life may have begun from a time where there are only globules containing crystal-like structures that pattern the formation of molecules, favoring the ones stable enough to survive and "reproduce" by splitting into daughter globules which later may have become the progenitor "cell" that sourced every life on earth. Basically, it could've been a "natural selection at the atomic level" and carbon won life, literally.

  • I would love to see a show reflecting on the ideas put forth by Per Bak in the book "How nature works".

  • A weird little theory of mine would be that silicon-based lifeforms would only form deep inside rocky worlds, where the intense pressure and heat might allow for liquid states of complex silicon chemistry. If that's the case, there might even be silicon life on our world, and we might never know it, as we could be separated by a couple thousand kilometers of inhospitable mantle.

  • I really think it's likely that silicone life exists, it may be extremely specific but in this game of numbers it's got chance

    • @Silver Back agreed, I feel like AI is going to kind of revolutionise stuff like this

    • @Good morning I'm super interested to see what variety of life is possible. AI can really help us with this, I think quantum AI will be able to help us find aliens

    • I agree, with how big and diverse the universe is, to me it’d be weird if the only life out there was carbon based

  • Fun Fact: Xenomorphs also use Fluorine in their blood which is powerful enough to break down Si-O bonds but also Si-F bonds are not as stable. Possibly the source of their acidic blood.

    • @Andy Davies better than wasting time in make believe topics.

    • @Dear Salamat you must be really fun at parties mate.

    • @Andy Davies the company that doesn't exist want me to believe Xenomorphs don't exist? Please explain how this works.

    • @Dear Salamat that’s what the company wants you to believe…

    • Plus Flourine is far better oxidising agent than oxygen that we use

  • mad props for including spire from mph. its was with that character i first learned about si based lifeforms and so very obscure i never thought seeing it here ❤

  • I still like the theory that the UFOs that traveled across the universe to get to our solar system didn't carry currently living beings with them. That essentially the UFOs printed them on site to be the probes to investigate things that they found interesting. Hence the little gray men. I love this theory it actually makes sense just like your presentation here does

  • I imagine silicon life is just a rock that 'breaths' in sulphur and excretes Silicon Disulphide through slow formation of crust, which then gets chiselled off by raining diamonds or something, and some other silicon based life feeds off that. It draws nutirients from liquid hydrocarbons on the surface. It would probably be a really really really slow process, barely noticable from a meat sacks point of view.

  • Made me think of the Vex from the Destiny franchise. Organic silica based life forms present as radiolaria that populate varying specialized metal chassis.

  • Thank you. That was something we need to know. And it does justify maintaining a carbon focus in our search for other life forms.

  • I liked the take the X Files had in the episode Firewalker. The Si lifeform they discovered was more like a fungus that incubated in your chest and throat. It was terrifying for little 10 year old me, and it's always been my favorite episode. I didn't even know what Carbon or Silicon based life even meant back then, and it really fascinated me. A nice bit of detail was that Scully even finds sand in the bodies left behind as waste from the organism.

    • @Kick 💩

    • @The🚫Hermit🍞Man you mean because it's full of their waste :D

    • Isn't there a theoretical possibility that actual fungus could evolve to behave like that in real life? So X-files may not have been that far off.

    • Hmmm. Would a Si creature hate beaches and deserts?

  • Excellent as always, thank you. Thoughtful speculation is a worthy pastime, especially as humans we owe everything to it. It's also certainly the case that the universe has a far better 'imagination' than any of us will ever have... but for life as we know it to be based on anything other than Carbon? I'll believe it when I see it.

  • I always imagined that if there's Silicon lifeforms they had to be at high temperature enough for SiO2 to melt or they are Rock life forms.

  • Always thought the problem of silicon based life was that it would have to breathe out sand. Now, is it possible to make electronics with carbon?

  • I remember a made for TV Star Trak episode where some kind of animal was killing workers in an underground mine on a moon. The killer turned out to be a large potato shaped "mother" trying to protect unhatched babies from the minors who discovered the nest and thought the eggs were just strange egg shaped silicon rocks - which they were destroying without any thought. The mother was highly intelligent and Capt Kirk negotiated a win-win deal between her and the human miners.

  • Hi Matt. I was just trying to sleep when I started thinking about black holes. I didn't really find an answer to my question so I thought I might try my luck with you. What happens when 2 black holes orbiting a third one. I imagine 3 equal mass black holes, one in the middle and 2 other orbits the third perfectly (aka, one of them is always on the other side of the third). I imagine their gravitational pull couldnt destroy the third black hole, but could their gravitation affect the schwarzschild radius of the third one in a way that its "pushed back" / the radius becomes smaller? Since the photon at the edge of the radius is "frozen" ,wouldn't the gravitational pull from another black hole help these photons escape?

  • "Sand is course and rough, and gets everywhere." You, sir, HAVE THE HIGH GROUND.

    • I AM the high ground Anakin!

    • @DigitalXAddict Darth Jarjar 😳

    • References aside it's a lot like life in that isn't it?

    • @Kwauhn I think it's funny that one can clearly see who got the reference and who didn't xD Mesa go electrify my tongue!

    • @embustero71 Well, what I meant was that Anakin was the one who said the line, and he had the low ground. But I like your interpretation too!

  • I originally imagined silicon working at much higher temperatures than carbon based life... like on a planet that orbits much closer to it's star than venus such that the silicon compounds on it's surface can melt. Then I checked the melting point of raw silicon vs silicon dioxide, and discovered that raw silicon melts at a lower temperature than silicon dioxide. Seems unlikely that there would be much structure for anything at those temperatures.

  • As soon as I hear Silicon based life, I immediately think about a movie-esque dystopian future where bad humans capture and use aliens to crush down into micro-processors to power further space exploration.

  • I watched a sci-fi movie recently that used boron instead of silicon as the base for an alien species. Is this a possible outcome?

  • Would silicon based life be able to use silicon's photoelectric effect to supply energy to the cell?

  • Incredible that life has evolved to include Si. So many options.

  • Small correction, the molecule displayed next to the dynamite is trinitrotoluene (TNT), not nitroglycerin. Love the chemistry content, always fun to see people loving my field 😁

    • I thought that indeed the explosive in dynamite is nitroglycerin, and not TNT.

    • I was just about to mention it, but saw you already did. Thank you! :-)

    • @Tadeusz Dybowski indeed, it was even used by WWII (i think) or maybe Vietnam to start a fireplace... vapors might have been "slightly" hazardous, less than enemy fire though...

    • @F C yup, almost you could say that some varietes can be placed in fireplace. All depend on additives which increase or decrease sensitivity. Diatemaceous earth added to nitrogliceryne is basically desensitizer. I was suprised there was no reference to that.

    • It's actually from his aussie accent, it's not a mistake

  • We already have silicon based life. We're watching it right now as we watch this documantary! 🤯 I think if silicon based life was really viable, it would be here of any possible place. All the factors would be here for it.

  • YES! Thank you guys for making this!! This is one of the important questions I wanted people to ask a while ago.

  • Life alwas finds a way, it can be anything and created out of something. We could have an alkaline based creature, or Iron-sulfide something. It would be interesting to see how life would behave and look under different elements.

  • I did hear emus can pickup a basketbball with one wing/hand. Very intresting about the silicon bonds being vunerable to oxygen. Had not noticed suphur being in the the same coloum as oxygen too

  • Might be stupid question.. but I wonder if one day we’ll be able to make silicon based life?

  • I'm surprised there wasn't a mention of the Horta from Star Trek (Original series). It's one of the few cases where they are truly alien - not bipedal, and them being silicon based was directly discussed by the other characters.

    • @kyle ellis The values for the brain seem to differ over the net, I'm settling with the percentages that the University of Heidelberg states, which is around 80% of water for the brain. And of course different parts of our body have different water percentages. For example, the more muscular a person is, the more overall water the body contains, as fat has a lower percentage. Which is also the reason that men tend to have a higher water percentage than women, which only seem to have around 55% overall. Oh, and babies seem to start at around 75% water overall.

    • Your Aussie jokes made this Aussie chuckle out loud, Matt. 😄

    • @Ruth Bingham yep 👍 I'm here to drop the phrase "Devil in the Dark" you beat me to it Ruth! 😎👍

    • The Devil in the Dark

    • @sp00n I was always taught our brains/organs are 90% water but the bodies is 60%

  • One of the most promising alternative life bases is sulfur. Sulfur can form chains, sulfur compounds can be dissolved in various solvents, and sulfur chemistry is probably diverse enough to include something that can be a basis for life.

  • My personal theory is that very different environments may prouduce very different life. Lack of Oxygen or Water, different temperature and pressure. Temperature and Pressure has a high influence on the chemical reactions and stability of molecules. The life may be very different from our life, for example, it might be very slow - would we even recognize something as life that is based on silicon, needs weeks for their equivalent of a heartbeat or breath, and thousands of years for a reproduction cycle?

  • Silicon based life might be impossible, but computers and so forth AI would be impossible to make without it. Episode about processors would cool!

  • Great video! I’ve pondered silicon based life ever since I first saw the Horta in that Star Trek TOS episode (“Devil in the Dark”)

    • Yes! I was looking for this one!

    • I took biology and despite sci-fi like the Horta Silicon is mostly wanting to form quartz. Notice that Oxygen is the most common element on Earth? It is mostly in the crust as an oxide of Silicon and other elements, but mostly silicon and Iron.

  • I think this is my favorite PBS Space Time episode. I love the answers after the main topic, but the main topic is also fabulous!

  • Imagine if there was like a silicon-based society that created a video titled “what if carbon-based life exists” at this very moment?

    • They did look at the crop circle that they described themselves as silicone basic

    • What if stupidity based life is not the only possibility?

    • @Susan Young An interesting supposition.

    • What if silicon based life forms dominated the early earth and created carbon based life as an experiment before going extinct? Sure is a lot of silica lying around is all I'm saying.

    • @benedictul Do you mean, "That's Sili"?

  • You are still the best because everybody is good for something but your knowledge is beyond normal people's intellectual. You do touch base on everything not just one, very resourceful rather than good at only one thing.

  • I think people underestimate the importance of water, it almost makes more sense to call us water based life than carbon based. Like you stated, life requires chemical reactions to do any work. A fluid is the most obvious medium for this to occur in, and there are other possible alternatives like ammonia which is also relatively abundant, but the chemical properties of water like it’s high specific heat/boiling point (reactions happen faster at higher temperatures), polarity, molecular size (think diffusion), and just how well it works as a solvent make it hard to think of something better

  • In fiction, I can only remember examples of Silicone based life being totally artificial or heavily implied to be artificial (the "Alien" series being the best example I can remember). I dont see how it could happen naturally, given the abundance of carbon in the universe.