Obsidian Properties and Formation

Welcome to the R of Science. I'm Hann Fryy. and I'm Michael Stevens. and this is an episode of Field Nes. Past expedition journey thing where we dip into some of your questions, a little mail bag and one of us brings an object every single week Yeah, so Hannah's brought the object today and I don't know what it is. And I love anticipation. So we're gonna actually start with you all And then after we answer your questions, Hannah will show me what she's got to show all of us today Queen Carvania stood haloed by the morning sun An army hung on her every word. My champions, I have sold my chariot on Carbana. 'twas a lovely SUV, an inexplicably queenly offer. They're even coming to the castle to collect it. Tonight, we feast An offer you can feast on. seell your car today on Carmana. Pick up fees, man apply. Hey parents, how do you make smarter choices for your kids college today? That's where Sally can help With Sally, you can find scholarships, funding options, tools, and guidance all in one place And if you need a loan, Sally has options for different families and different situations College is only worth it if you do it right So don't just help your kid go Help them go smarter Sally d. com slash go parents This episode is brought to you by Cancer Research UK. Scientists have found that cancer risks usually increase with age and size, but some species defy the odds. For example, deep sea Greenland sharks. They can grow over six meters long. more than a small car and yet live for up to four hundred years. Now understanding how Green and sharks cellular repair and immune systems seem to have managed to keep them cancer free for centuries, that could open up exciting research pathways. Essentially over millions of years, evolution has been running the world's most successful cancer prevention trial. And sometimes breakthroughs can be found in unusual places So by exploring the unexpected, canancer Research UK scientists are uncovering new ways to tackle over two hundred types of cancer. Their work has helped to double survival in the UK over the last fifty years and continues to save and improve lives around the world. For more information about Cancer Research UK their research and breakthroughs and how you can support them, visit cancerreesearchukot org slash the rest is science I'm going to jump right in with a question that came from Ben. Now Ben asks If you were out in space, say right in the vicinity of a pair of black holes colliding Would you be able to feel the gravitational wave from the collision pass through you Would it depend on distance? And if so, how close would you need to be to feel it Or is it inherently impossible to detect since the space around you is getting deformed the same way you are? Scary question I don't like big things because Even evenven the solar eclipse really terrifies me Not so much that I don't want to see it. I want to see every one of that I can and I have ever since I got like addicted to them. But in the moments before, like the day of, I start just my heart won't slow down because the scale of it, the size of the moon and the sun doing a thing together, I mean, not that they really know. It's just too big and I can't stop it S sorry I'm going on a tang on sol eclips But a black hole collision would be the same way. I am so in the mode of Control because of our modern world where I can pause a streaming show, I can resume it later, I can rewind, that I just feel like I get to control everything. I click on the links that I want, I scroll when I want, But with the Solar Eclipse does not work that way. It's going to happen when it happens And you know when it's going to happen and there's nothing you can do about it. And that is so alien to our world today it freaks me out. It's terrifying. I remember this moment, the first time I had that realization of how small and insignificant we are in comparison to the vastness of space, the sort of the The fact that we are along for the ride, right we're completely insignificant. And I was fourteen years old and I was in a science class at school. and honestly, this existential dread lasted for I would say about ten days. I was like not sleeping at night. really It really got to me. I suddenly felt just so unbelievably insignificant I'm not sure I've quite got over that ever, actually. I think's I think I was sort of a before time and after time, you know, beforefore that realization, happay and free. And then after and you're still living in the after. I say congratulations. I think that's an important realization. Now did you try the aneidote which is to instead focus on how much bigger you are than the quantum world Th then start to feel like a giant going around crushing things. I think that that would have untethered me from both directions simultaneously. I think I would have been adrif. You're right. It doesn't actually work because then you start realizing that the neutrons don't care about you either. M. H, Almost nothing cares about us, Michael. Almost nothing. But you know what, thenen I care about you And you're probably taller than me, just on average. So the smaller world does care about you, kind of So here you go Gravitational waves, they are literally a changing in space itself And they're flowing through us all the time. In order to detect them, we need really big ones The first one ever detected was detected by LIGO in September of twenty fifteen. And then they announced it in February of twenty sixteen. So they took a long time to be like, whoa, are we actually seeing waves in space gravity waves And the first thing you would feel if gravity waves went through your body that were powerful enough to be sensed. The first thing that would happen is you would hear them because your ear, your eardrum is your most sensitive vibrational detector. I don't know what it would sound like Because sound, especially just manual manipulation of the eardrum, or is it really manual? Satial, spaceet timee warping of your eardrum be like pressure waves in air As far as the mechanism is concerned, The frequency of a gravity wave can be pretty low, like half a hertz a second It's probably gonna to sound more percussive, more like And I want to give full credit to a Reddit user named Carbon Cubit. I'm not afraid to admit that I'm just researching these things. It's not like off the top of my head, I know everything Carbon Cubitt did a really great breakdown of that first detected gravitational wave, which came from a Black hole, a binary collision that happened one point three billion light years away That gravity wave was immensely powerful. Basically two black holes, one that was thirty six solar masses, and another that was twenty nine solar masses collided to form a sixty two solar mass black hole. If you're doing the math at home, three solar masses are unaccounted for. That mass, according to equals MC squared, turned into energy gravitational wave energy of space expanding and contracting, and it's spread out. But gravity waves, just like electromagnetic radiation, gravity waves They spread out and the energy per area goes down by an inverse square. So if you're twice as far away from the collision, the amount of energy you receive is Four times less, a quarter of it However, the amplitude gravitational waves just goes down linearly. The amplitude is the height of the wave. So what that means is that Earth, one point three billion light years away gets hit by these gravitational waves and Earth itself really did squish and squeeze by about a distance of a dozen protons in a line because of those gravitational waves. First of all, that shows you how amazing LIGO is that it can detect something like that. Let's bring that collision closer Rather than one point three billion light years away, let's put it just one light year away thenen what happens Well then Eth only. expands and contracts by about twenty microns, twenty millionths of a centimeter Still not much No C you bring it closer still, brring it closer. Okay, let's bring it as close as the sun, okay Bring it ninety three million miles away, just eight, like eight point three light minutes away. thenen Earth would expand and contract as space itself ripples through changing Earth would expand and contract about one meter about three feet. And this would happen quickly Earth expands and contracts by about a meter just because of the Mon's presence. That's what you know, the tides are causing these changes U But imagine if instead of taking twelve hours to happen The frequency was like once every two seconds, that could be bad Our bodies, I think would be fine Earth would not. We would see geysers erupting, volcanic eruptions, massive, massive tsunamis as the ocean absorbed that energy. But I think could some of us could survive it. And wait, why do you think that the human body just because we've got enough flex and at the scale of us, actually it's not that big of a deal? think that over the scale of a human b body I don't think it would be as Bad on us What is a real shame? justust going back to your point about ears, It is a real shame that your ear canals are not perpendicular to one another. becausecause then you could be your own individual LIGO, right could uh You could sense the pressure difference in a much more attuned way because they're sort of, I mean, I know they're S shaped, but they're sort of on the same axis, aren't they? They're sort of like pointing towards each other. Yeah. I think we are just not massive enough to be as affected by gravitational radiation as we are by electromagnetic radiation. So the Earth itself might you know, expand and contract by a meter, but the human body would would not Yeah, I think you I think you're right about the ear thing I think I think you would detect it by hearing it. or feeling some sort of strange sense of balance. Oh yeah, your sense of balance would get messed up. That's also a very sensitive organ in your body. I forget what it is, but our ability to detect an incline is actually amazing. I think we can tell the difference between Like the second hand standing on a floor That's a second hand pointing at nine. so horizontal versus a second hand that's like One second past the nine. we can tell Yeah, we can go, oh, our inner ear is like, hey, I'm different now That's interesting. You'd probably get dizzy You'd probably feel nauseous and you would hear like a like a whing But That would be very small in comparison to at the scale of the Eth and the oceans the volcanic stuff In terms of your body though I think the key thing here would be the frequency of the wave, right? Because If you're talking about a really low frequency, I don't know, black holes orbiting each other where it's, you know mayaybe not point one hurts, not point one hurts. you know, the waves are actually quite slow, then I think the body could resist quite a lot. But if you're talking about, I mean, Ben talks about colliding black holes, doesn't he? Oh yeah, from a collision The collisions are higher frequency likeike a hundred times a second very disruptive to your blood vessels to just your makeup I think you'd have a better chance of hearing it too. I mean If the gravity wave is just is compressing space in a large area, then your eardrum' just moving with your body, with your nerves and you might not hear anything. We need tidal forces that are small enough that the eardrum's moving differently than the rest of your body. The bones in your ears are being moved differently than each other, and that becomes a very hard to ignore noise I guess it really depends. I guess I'd say that there's definitely a way if you could create any kind of gravitational wave, you could certainly affect a human. After all, we're made of matter. But E black holes at a distance of our sun They'd have to collide create a very high frequency wave And then yeah, your body could get mean not pulled apart, but stretched and squeezed to the extent that you weren't like blood flow would be interrupted. Well it would be accelerating and decelerating and that's the thing that would That would be difficult with it, right I mean Parts of your body did not enjoy accelerating away from other parts of your body. Yeah, the differences in acceleration would be very uncomfortable. Like if I just got moved all togetherether, it'd be like riding in a car. But if my head is moving in one direction and the rest of my body' being accelerated in another direction I get uncomfortable Can I get torn apart Yes, I can imagine And I can describe gravitational waves that would tear you apart that would actually be more pleasant than the kind that just bother you for like an extended period of time, cutting off brain to various organs. but The point is, gravitational waves from extremely powerful black hole collisions a billion light years away, we don't even notice them. We have to build extremely sensitive equipment and then analyze the results for months before we go aha Yes. So one point three billion light years away, two black holes collided and in two hundred milliseconds, The same amount of energy was released from them as all the stars in the universe do in the same amount of time. But it was so far away barely noticed it. Basically, spaghetification is going to be a problem. before before the gravitational waves are. You have to be so close that you're going to be stretched with within the sociales. You know, it's not so much spaghettification as it is knedification. You're being kneaded like doough. I want to leave as an exercise to the listeners. What amount of gravitational wave kneading would actually just feel good? What would be a pleasant massage? You know, When you go to an airport and you sit in one of those massage chairs, what intergalactic objects would we need to collide to create that sensation? All day every day? So the answer to your question, Ben is that yes, we will feel it and we can feel it H. Goodly or badly Okay, next question, we have got one from Dan who asks people have been talking about space junk or trash. Thank you for the American translation there I appreciate it. in the Earth's atmosphere for a while now. But if there is so much of it, Why can't we see it in photos from the ISS Great question and you're right that actually there has been a lot. of chat about space junk. There's a couple of reasons for this, right? By the way, when we say there's a lot of space junk, there is a lot of space junk. So there's some estimates that put it at fifty four thousand tracked objects that are bigger than ten centimeters fifty four thousand of these things. And by the way, if you are willing to drop it down to any fragments above a centimeter So not just kind of like ten se is massive, right? If you imagine like, I don't know, like a mobile phone. You're sort of orbiting the Earth and a mobile phone come and whacks you in the face, right? Anything bigger than that, anything bigger than mobile phone is there's fifty four thousand of them floating around the place. But if you go smaller, if you're like anything down to the size of a centimeter and above, it jumps to one point two million. which I think is astonishing is like that is litter city up there. It's absolutely phenomenal. If you're like, okay, we'll go even smaller, anything above a millimeter. So you know, like a screw, for example, or like just a little bit of shrapnel, then there's around one hundred thirty million bits of space junk. This is all stuff that we have just Scattered around the place, by the way. This is like, we are solely responsible for this. Now no one wants to get hit by a screw traveling at hundreds of meters a second. You do not. So you're talking about a lot of material. However, it's spread over a very large area. and like, I don't know a lot about space junk or what space trash is that what the Brits call it I think trash was for your benefit, frankly. Oh, no, we call it space junk. We love the word junk anyway. I don't hear about space junk hitting the ISS or even satellites very often for that matter. No U Okay, so a lot of it, the first thing is that the ISS is actually quite low. So a lot of this stuff is like is kind of around floating above in a different orbit to the ISS. I do think this is something to worry about in the sense that this shrapnel was moving at like twenty eight thousand kilometers per hour And like that is so fast that a tiny screw could really damage the outer exterior of a vessel, especially these things are notght You know, they're not armor plated. They're not sort supposed they're not kind of designed to deal with this all of this stuff coming in. Can you even armor plate yourself against this kind of a collision? Well, I don't know, I mean there was an example in two thousand nine where satellites have been genuinely destroyed by this stuff. There was the active communications satellite' called Iiridium thirty three, and it collided with a defunct Russian satellite. So we're not talking about time a bit space shrap, but we're talking about something quite big here But yeah was just was taken out by that collision. So I mean, the problem is is that even if you could armour yourself against all the little bits, there are giant honking great big things out there too that can potentially get in your way Now I agree with you that the amount of actual space that you have He's Vast, right If you think about the entire surface of the atmosphere of Eth, right? It is gigantic even if you're talking about know fifty four thousand objects bigger than a mobile phone. And so you're sort of talking here about like I don't know, is sort of a grain of sand, but in the size of a cathedral, know And there's many, many, many of those cathedrals next to each other, but they are very spread out over a long know really far distances And typically even in the sort of busiest lanes, the busiest orbits The nearest piece of junk will probably be one hundred plus kilometers away So so there is a lot up there, but there is also a lot of space However, what I will say this idea that you can't see space junk in images from space is not true because there is a edditor called Responsibility number twenty ninety seven who has stitched together all of these images of the earth from the Artemis mission and created this video essentially of our planet And what is really intriguing about this is that in each individual image there's like a little bit of kind of scattering around of light. But when you watch them in a row, you can see just at the edge of the atmosphere You can see these satellites moving around. Do you see it Yeah. J on the edges. It's really hard to see when you're looking directly at the sort of center of the globe, you can't really see them, but just on the edges where they're catching the light from the sun You can see these little specks floating above the earth. and that is collection of both satellites and space junk. I'm not surprised, I mean, these things reflect sunlight really well So even though they're tiny They can send off a lot of light. In fact, I was once walking around on a little night hike with Jake Chudnow, the guy who makes all my music. and we were talking about satellites. and he said, yeah, you can even see them in the sky sometimes. We looked up, we all immediately spotted one It wasn't the ISS. It was a we even saw like one of those, what do they call them like an iridium flash or a where it just happens to catch the sunlight and it shoots it right down at you. And it was this spark of light. And we were like, oh my goodness, the coincidence. We were just talking about this phenomenon We can yeah, we can see the space junk We certainly see satellites in astrophotography. and the number of satellites up there now I've heard really affects the quality of some images because you do time lapses and you wind up with streaks of all these satellites. I have actually spotted them mean like literally from my garden in London, on a clear night, I can see you know particular conditions where you have a really clear night and the right time of the evening. I have seen a starlink train where you sort of get five or six satellites kind of moving all in the line That's very fun to spot The thing about Space junk is that this is going to be more and more of a problem as time goes on because more satellites being launched, the more risk that you get of debris being thrown off, the higher risk of collisions. unless you have this really a sort of collaboration, a global collaboration to have clean up or some sort of traffic management thing. This is genuinely going to be a problem because actually even tiny Paint flick because it's moving at that sort of speed can end up damaging a spacecraft. There was one example of a paint chip hit a space shuttle window and left a crater in the window, right? And this paint chip weighed you know less than a grain of rice. But at these sorts of speeds, this is genuinely something you have to worry about I'm sure it'll be automated In the future the job of space Trashman would be so cool. I like the idea of going out there with a net, you know? Yeah, with a big net. And you get to keep what you find And It's a hard day's work. A bit of apollo. Yeah. Oh, hey, look. I mean, have you weed something, right? Go go and grab Sputnk. It's still up there. is it I don't know actually. Maybe its fell to earth. No. In nineteen fifty eight After just three months of orbit, it burned up while re entering Earth's atmosphere. There's probablys of bits of sputit junk up there There could be Sputnik junk. Can I tell you a tiny thing about Sputnik that I just think is absolutely amazing So Sputnik really freaked everybody out, right? Eespecially the Americans because It's this idea that you feel like you've got control over your own airspace and then there is this foreign object that you know is in the sky above you. And what the Russians did is they deliberately had Sputnik send out this ping, this sound that could be heard on actual radios, right? L actual radios could pick up on this If you were in the right place at the right time, you could hear this ping of sputnik going over And it's just so ominous, the sound. You couldn't hear it with your ears directly. You had to tune into its frequency. and people all across America, all across the world were able to go, oh my gosh Oh my goodness me. Yeah, it's here, it's there. it's above us in the sky. No ground invasion necessary. I'm just here at my dinner table and we're listening to this thing. Is it watching us? No one knew how well it was detecting what was down below. But then what happened was a couple of students they realized that the hing on the radio The frequency of it would change depending on which direction or where above than Sputnik was, right? Essentially, they had the Doppler effect. So when a car goes past you and it goes p, the frequency of that noise changes as it moves across. And it was the same thing was happening with Sputnik's pings across the sky that it would sort of speed up and then slow down as it moved closer and away from you. And so these students, like literally these people tuning into a radio, managed to work out the trajectory of Sputi and predict exactly where it was going to be and exactly where it was going to be going, purely based on like Beef You know, a bit of Pythagoras and a radio. It's absolutely phenomenal. loveove that story. No, that's really cool. What a fun little project. F, but kind of scary. I mean, this Buttniick was like the first truly was the first humuman made eye of Sauron was not an angel or a demon that was watching over you. It was a physical thing by people with names that was watching or at least there be watching C be watching. There might still be pieces of it up there, but you know what? Be it burned up There are pieces of it down on Earth still There's Sputnik dust. You've probably touched some of it. You may have even breathed some in. You've probably breathed some in In fact, you almost certainly have Yeah, it's like a breath from Julius Caesar. It's out there in the air And so Sputnik used to be watching over us and now it is in all of us. This is why listening to this program is so great. Right now, you know, when someone tells you to take deep breaths now, you can go Juliia Cesar Sputnik. Dinosaur farts, right? You know every breath has a little bit of wonder. That's why I fart so much. I want to leave a lot for future people to experience of me. V so. Exactly, exactly My grandkids will be like, man, I miss the guy It's like he's right here in my heart. Yeah. And in many ways, he actually is. I want to do one more quick question because I love this one and I actually recently learned about learned about it So so Lawrence wrote in and asked, Hello, I love the show. A, thanks, Lawrence. And I have a mechanics question that's been bothering me forever as an engineer. But I can't get my brain around it Let's say I'm leaving the London Uground, but I'm tired and I'm in a hurry. It's a normal day. I'm standing on the escalator, watching people walk up the escalator and people use the stairs and I wonder, is it less or equal or more effort to walk up an escalator than compared to walking up the stairs feeles like it's more effort to push against the rising escalator, but surely the escalator is helping Please help I love this because I think about this stuff all the time too about, you know, what's gonna work my muscles out more, you know As it turns out, so yeah, when you step onto an escalator, your body is accelerated by the escalator, but it's accelerated up to the escalator's speed and then you're there. Any further steps you take are no different than just walking up regular stairs. If you step on the escalator and fight it, then momentarily you are doing more work. But no, if someone's walking stairs or walking up an escalator they're already on, same experience. However, let's talk about stairs because it is actually really complicated and still a bit unknown What's B If you want to burn calories and use up energy Walking upstairs one at a time? Oh two Yes So, here are the variables in play. First of all, if our bodies were just simple machines, it wouldn't make a difference because work is just your mass, times gravity, times how high up you go And if you go slowly one step at a time, well, then you know, you spend a certain amount of energy. But if you do it twice as fast because you're skipping every other stair, Well, you spent more your rate of energy expenditure was higher, but you spent half the time I'm spending it. so it's the same. But of course, biomechanically, our bodies are not little simple machines. and faster changes in muscle motions are less efficient and therefore burn more calories. researchers have worked this out and we can put some of the papers below They have measured respiration and heart rate as a proxy for calories burned. And they found that taking the steps two at a time does burn more calories per minute However It's not S. Yeah, as it turns out, walking up a flight of stairs one at a time actually burns more calories because of the way all these biomechanical efficiencies work out If you are going to be walking upstairs for a certain amount of time, like for I'm gonna to spend ten minutes walking upstairs, then you should do ' them two at a time. But if you're just walking up to your office, you know, you're walking up, I don't know, two, three flights, then walking taking them one at a time, rather will burn more calories. And they actually calculated in the paper that if you climb a fifteen meter stairwell five times a day, that equals three hundred and two kilocalories per week if you take them one step at a time, three hundred and two. But if you take them two steps at a time Only two hundred and sixty six kilocalories. Hey, lookook, that's the difference between probably four peanuts across the course of a week. It's funny that you mentioned peanuts Is it for peanuts? I've got peanuts right here. I'm a big peanut head So thirty nine peanuts is one hundred and seventy calories. Okay, I did the math and that's an additional four peanuts. Big time. I have a question for you now, Michael. If I mention anything, have you got it in your room Is there anything like sort of feel like I say, you know, peanuts and suddenly they appear. I say bath bag and suddenly it appears. I say beard hair and suddenly appears. Is there anything I could say that you don't have? Let's try it. Lets just I get one shot. I want you to name an object, a thing, a type of thing, and I'm gonna see if I've got it A whistle. I've got one in my mouth. Does that count I honestly don't think I have a whistle Hold on. Okay So I cannot immediately imagine a whistle. I think this gyroscope whistles, but I don't have the cord that spends it But it's got little holes along it so that it can whistle. It's obviously supposed to sound like a That counts. That's amazing. Does that count What about what about I was trying to think of ordinary objects that most people would have that you wouldn't have. Do you have a mirror Yeah, I've got mirrors. I've got mirrors in the bathroom and I've got little glass mirrors for a little optics experiments. Okay, You can put in the comments below, by the way, of objects you would like to see if Michael has in in his Aladdin's cave. I don't have plate. You don't have a plate. Yeah, I don't I eat off of off of paper towels basically is I don't have a need for a plate But I do need A bag of my own beard hair Yeah and and a UFO that makes a whistling noise. Yeah Okay. and I do need, you know twenty peanuts Well, look, you need to give yourself a little treat for all those stairs you climbed. makes a lot of sense. Yeah. so bottom line is walking up the stairs per flight is going to burn you more calories because even though it does take a bit longer, but also the quicker movements or there's more movements required overall, because you've got twice as many steps So the math works out such that you do burn more calories per flight of stairs by taking them one at a time. I guess going back to the question then, taking the escalator and walking up them Also takes less calories because there's less time on the escalator. There's less steps effectively. That's right. And there's fewer steps because although you're walking up some steps up at the top you know every so often, they're disappearing. There you go. enoy enjoy your free peanuts with that piece of information Okay. We are going to go for a little break, I think. and when we come back, Michael, I want to ask you what is the sharpest object? I'm going to say in the universe, what is the sharpest object in the universe? Okay? This episode is brought to you by Google Chrome. You think you know a browser, but Gemini and Chrome, that's new. It can help you with practically anything on the web, like restoring a vintage motorcycle from a fifty page restoration block, or finally break down that long article you've had open for weeks. Gemini and Chrome is here for it. Ready to make anything online makes sense? There's no place like Chrome. Check responssees set upp required compatibility and availability varies eighteen plus And we're live on Match Day as Doug reaches for a buffalo wing. He's got it. Oh and he's gone for a can of Pepsy too. What a finish! There's no doubt about it. It just tastes better. Match Days deserve Pepsi When you need to build up your team to handle the growing chaos at work, use Indeed sponsored jobs. It gives your job post the boost it needs to be seen and helps reach people with the right skills, certifications, and more. Spend less time searching and more time actually interviewing candidates who check all your boxes. Listeners of this showel will get a seventy five dollars sponsored job credit at indeed dot com slash podcast That's indndeed d. com slash podcast. Terms and conditions apppply. Need a hiring hero? This is a job for indndeed sponsored jobs. Allright, Michael, what have you got for me What answers have you got? Your mind. Hey, dan dan dan danan. Cfence will get you everywhere, but it's wrong. nextext. That's not what you're looking for. I mean don't I don't know. I've always wanted to know more about sharpness, so I'm glad we're gonna to talk about it today. I'm assuming it's gonna to have to be something That is made of a very strong crystal that comes to an edge that's like one atom wide. Okay, it is not a crystal. It is a rock on. It's sort of a rockette, if you like, and you're right that it comes to a few atoms wide. So technically you can get things artificially made that are one atom wide, but they're not very good for cutting. So I want something that's like Hardcore good at cutting. Is this thing that you have a natural thing? It isal Oh, I love that. Sos like it's like the sharpest naturally occurring thing Yeah, which also happens to be basically the sharpest thing Okay, tell me more. Okay, the answer it is a rock and it's another one of my rock collection But why are you laughing? are are you like ashamed Y're how many rocks do you have 're We're going towards the end of my rock collection, but I'll be honest with you, I love a good rock. okay? I love a good rock. I'm going to show you the rock because it's polished. Look Whoa. Look at this, Isn't it pretty? It's like a little orb. It's very pretty. What is it? What I'm holding is a very heavy black orb. It's been perfectly polished into a really glossy sphere. And this, my friend, is Obsidian. Oh, okay, I'm gonna tell you a little bit about Obsidian. But before we're done, I'm gonna tell you how Obsidian, this little black rock can decapitate horses, has been crossed an entire continent to be buried and has helped people talk to angels. o This is this is like a very good rock. It's a very good rock By the way, you're hold you're holding a sphere of pure obsidian that's about It's a little smaller than a magic eightate ball. Yes, that's a good description of it. It's very heavy as well. It's like super, super heavy. I can see the lights from your ceiling reflected in it, but otherwise it very much is just like a black hole. It's kind of glossy actually. Yeah, it has a little stand. So it sort of looks a little bit like it belongs in a fortune tellers. It kind of looks like it would belong on a fortune teller's table. It's very mysterious. Okay, so here's a thing, right? So Obsidian, it's a naturally occurring glass Okay, so way, way, way, way, way before glass was actually manufactured, this stuff was around and was on the planet. And it's made. It comes out of a volcano gets made when lava spurts out and it cools so fast that all of the atoms are really disordered and so it kind of freezes sort of mid panic Right. So this is how you end up with with glass essentially is that it's like sort of a liquid state but then frozen into solid. Okay, so it hasn't had the chance to crystal R Because what would normally happen if you get know lava spurting out of a volcano, if it manages to cool nice and slowly, then what happens is all of the atoms sort of take time and find this much more crystal like structure, sort of a mineral, that's what would make it a mineral. So technically this is not a mineral. Geologists call it a mineraloid, right same categories as pearl and amber. Right. Be it not hasn't got the same structure. Anyway, so this, by the way, is the exact same stuff as Pumice. You know Pumice stone? Yes, I was thinking, whereere does pumice fit into this? Because Pumice is the only other kind of lava based rock I can name. Okay soumice and Obsidion, exactly the same stuff. The only difference is the water content So as it comes out of the volcano, so normally pomise comes out first, right? They're both made from rhyooltic magma. so exactly the same really high senea content. And what happens right at the very beginning of a volcano eruption, there's like lots of water that is you know, in gas gasser state. And so, u If it comes out and it's really frothy, all of that water is like bubbling inside of the lava. And then it cools, you end up getting pumice. And so all of those like air bubbles effectively give it that sort of porr shape of at the end of a volcano eruption, sort once lots of the water has disappeared, if you have a really low water content and it cools really quickly. so usually at the edge of the lava flow, that is when you get this volcanic glass. That's when you end up getting this stuff. because you just don't have any of the bubbles. So Pumets and Obsidian have the same like atomic or even molecular makeup however Pumus has had so much water content in it at its formation that it's like not dense at all. it floats even. U Do if the does the pum is cool really quickly to the point that it's also like made of obsidian that's just like spongy? I don't think so. I think that pumice ends up having more of a mineral structure. Right, I think I think. I think it has a little bit more time. Look actual geologists can correct me mean this. I'm an amateur I'm a sort of bystanding like an extremely excitable bystander U in all this geology stuff But the thing about this glass, okay, the reason why it ends up making the sharpest object I'm going for it in the universe is that when it breaks, because it hasn't got this crystal structure, it means that there doesn't have this sort of preferential kind of cleavage break that you get when you normally break rocks. And so instead, if you smash it, I mean, this has been like beautifully polished, but if you smash it, it ends up breaking concoidily, right in these really smooth curved shells, but like normal glass, right? if you sort of take you know, human manufactured glass, you get these these sort of they literally look like clamhells, right? Like these sort of these shells that come out. and that is when you get these incredibly, incredibly thin edges that can be like a couple of molecules thick Right? like nanometers unbelievably tiny. And this is the thing about it, right? Th theseese edges that you can get with obsidian are so tiny that they are thinner than the wavelength of visible light which means that this cutting edge is literally too small for light to be able to see. You can't even see it. It doesn't matter how big your microscope is, you cannot even see it. For contrast, by the way, like a steel scalpel, even the best steel scalpels that are made manufactured to perfection by sort of human design, if you magnify those, what you see is this like serrated ridge of metal grains. I mean, they' like they're like boulders in comparison to this stuff. It' like It's like ultimately a surgeon's knife. once you really get down to it, it's like a bread knife. You're sort of getting hacked apart. by microscopic bread knife Parisin is really helpful. That's very yeah. So a surgical scalpel is just like a crered sand dune compared to an Obsidian blade Why don't we use obsidian blades in surgeries? But we do. So this is a new thing that is happening. actuallyually, lotots of surgeons. mododern heart surgeons in particular are really pro having obsidian blades. The only thing is it's very brittle. so there is a risk of it breaking. I was gonna say, yeah, the brittittleleness is gonna become a factor Yeah, but there are I mean, they're much finer. You get much cleaner incisions. Wounds heal faster as a result because you haven't got this sort of like jaggedy edge that's between all the tissue. The thing is is that actually because they're quite brittle and they can chip There's also this whole thing about diamond scalps because diamonds, you can manufacture it to get it incredibly clean, incredibly smooth, to get it down to sort of a few molecules thick as well. But yeah, this idea of us going back to these naturally occurring rocks to get really, really incredibly sharp stuff I just want to go back to this whole thing about it about it not being a crystal, about being this glass thing. becausecause the thing is is that Obsidian is also the youngest rock on Eth And the reason for that is that every bit of obsidian that exists is sort of rotting from the inside. The thing of glass is it's this amorphous solid. So it's essentially' got the molecular configuration of a liquid, but it'sort of been frozen into a solid state. And that is not stable. So what happens over time is that all of these atoms that are trapped in this state that they don't want to be in, they very very, very slowly start to crystallize. And so Obsidian is like permanently, imperceptly, but it is permanently sliding down this scale into just becoming an ordinary stone. Whoa. It will only exist for a short period of time. How short of a period of time? Not that sh. Like we're still talking probably millions. Yeah, but compared to a normal rock I mean, basically is there is no obsidian at all anywhere on the planet that's older than twenty million years old. So this is the thing, right? The dinosaurs definitely had obsidian. It was all over the place, but we don't have it. Whoa. So There must be transitional obsidian where it's like not pure anymore. It's becoming a crystallized mineral. There is. Have you seen it? It's called Snowflake Obsidian. Wait, wait, I think I have seen this. Like snowflakes in it Yes. And those are the crystals. Those are the crystals. That is the little white florets are these little crystals, but it's basically the obsidian kind of surrendering. It's the obsidian dying in slow motion And this is it. we sell it as jewelry because it's beautiful But it's literally dying Obsidian in your hand. Okay, so if you buy a piece of Obsidian, you're really preorddering some quartz and Feldspar. You are. It's got a long lead time. But put it on your shelf, it's worth the way. It's worth the way,'s worth the way. Anyway, okay, let me tell you a ton a bit more about Obsidian, right? Be this stuff is so I love this stuff because it is, I think miraculous to us now. you know, surgeons are using it, but it has been miraculous through time, right? All of our ancestors were also obsessed with this extremely strange volcanic glass. So one thing that's worth saying about this is that every volcano has got this unique chemical fingerprint. so there are like trace elements that are tracked in the glass that happen at the moment of eruption. So what you can do is you can take a piece of obsidian and since the nineteen sixties, there's this method of a way to analyze the minerals and work out exactly what volcano it came from and exactly when Okay And what this means is that when you find chunks of obsidian on archeological sites You know where they came from. So we are going back to your manuport stuff, my friend. I was going to say, yes, it sounds like so then we can look at old human you know inhabitated places and say, o, where did they get this from? How long did they carry this? Uhh. How long do they carry this? How far away do they carry it from? And there are some wild Obsidian stories. So okay, Obsidian, it turns out not only is it the youngest rock, and the sharpest thing. It's also the oldest trade that we know of because three hundred twenty thousand years ago, Right at the beginning, beginning, beginning of our species. in Kenya, there are finely worked obsidian tools. that were found at site This is sort of between layers of sediment, that's how they managed to age you know what point in history they were laid there. They were found at a site with no obvious obsidian source of its own and it actually came from a volcano that was ninety five kilometers away It is way more, way further than a hunter gatherer would travel in, you know in a whole year. It's not just like have it in your pocket and off you go. It's like this is the oldest evidence that we have of exchange between R That's the only real explanation of how that could have happened. How cool that it must have been trade routes. There's also thirteen thousand years ago, so I'm sort of skipping quite for a lot in time here, but there is some obsidian thirteen thousand years old, sorry, thirteen thousand BC so what's that? fifteen thousand years ago. Yeah. My bad. fifteen we can talk again about how the Clenda is nonsense. Okay, fifteen thousand years ago, this is there's a cave in Greece where some obsidian from different island It turns up in this cave, okay, fifteen thousand years old, and this is the earliest evidence that we have that humans were seafaring. So this island is like there's a hundred kilometers of open sea distance between the two of them. It was almost certainly that they traversed it in these reed boats. This is before farming, by the way, this is before pottery, this is before cities, this is before I mean, civilization in any real form as we know it and humans were sailing open waters carrying this stuff. Wow So obsidian has been cool to us for a very long time, almost as long as we've been a species also tells that story hour prehistic past It really does. And I think the reason why this stuff was so valuable is in part because of its sharpness. There are some stories. The Aztecs, by the way, were particularly obsessed with Obsidian, in part because they didn't have steel, right? know while all of Europe was making steel blades and armor plating and chain mail and all of that. The Aztecs, they were a society that was really focused on obsidian U And there are stories from the Spanish conquistadors, is that how you say it time Key to doors thank you. The Spanish conquerors who went over to try and capture territory in Mexico and sort of around Central and South America. and the Aztecs had built these Makuhuto I don't know if I'm saying that right. Look, as tech experts, you can let me know in the comments how I'm getting this wrong. But essentially it was like basically a baseball bat but with Blades of obsidian stuck all around the edge. Oh no And and this is a bit grim. So if you are, you know under the age of twenty five or of feeble nature, then closure is for a moment. But what would happen, this terrified the Spanish because the Aztecs the Spanish rode across the hill with their horses, you know, ready to invade, ready to take down the locals, the Aztecs could decapitate a horse with just one swipe of this obsidian Med bat. Wow, because it's just so sharp. it doesn't take much force to just go all the way through the horse neck Right. I mean, that is grim. And also of course theseort Spanish people were probably quite frightened and there was probably some exaggeration in the reports of it. But yeah, the Aztecs knew how to make their weapons were obsidian weapons. Can I just say, I love how sharp this stuff is and how well you've explained it. and yet Your sample of obsidian that you brought for field notes is the least sharp A piece of Obsidian can be You're like, it gets really sharp. By the way, here's a perfectly polished sphere of it Look, I could smash it for you, but I think I don't have the relevant health and safety equipment to deal with the sharpness. Yeah, I'm not gonna ask you to smash it. Remember when you asked me to lick An undersea nodule and we didn't even know the health consequences, that's not me. that's you. How are you feeling, by the way? I'm feeling fine. I think if there are any consequences, I'll notice them you know, decades from now. Okay, so I have one last thing to say about Obsidian, which I think really demonstrates how it connects us to our ancestral past So the other thing that the Aztecs were really big on and it sort kind of explains why this one is designed as an orb in this sort of the style that you would see in a fortune teller's tent. Because actually what Obsidian was also used for a lot, well, it's the earliest form of mirror that we had because it could be polished so perfectly that you can see your own reflection in it We have mirrors going back eight thousand years. eightight thousand years. By the way, manufactured glass is probably only about four thousand years old. so you know, way way, way, way, way before that. But what people would do, the Aztecs in particular is that they would use this to Connect to the spirit world They would look into polished Obsidian and use it to talk to angels, use it to talk to people in the underworld. There's a very famous Aztec Obsidian mirror that is now in the British Museum. this Elizabethan occultist, John Dee would use it to talk to angels. Let me show you something real fast If you've got some obsidian, Michael I got a crystal.al b. I' got a crystal ball! Look at that. so Michael has brought up his own crystal ball. His is manufactured glass rather than natural glass and is perfectly see through. But what is quite fun about your one, because you can see through it, you can see how your image has reversed through the other side. Gone put your head up really close to it. I want to see your head upside down They are you are Dan slightly Hold on, hold on, let me just Come on, M, it goes right you can do it You what a what what a cool comparison. We've got Earth made not the ball, the humans bls into a sphere, but your material is a natural material obsidian. mine is U, completely humuman made. And Very heavy Go, keep going, keep going up,, Yeah Isn't that amazing? That's good. I enjoyed that. I enjoyed that deeply. So there you go, that' my object for this week. You've got one of my favourite rocks, sort of perishable, the oldest thing we ever carried on purpose that we know of, the sharpest edge, sort of a mirror that we've gazed into for eight thousand years. That's really cool, Hannah. And here's what I like about this, okay? So we know that our ancestors were obsessed with this stuff. We know that our ancestors would stare into a black mirror to see images that were beyond the world they existed in Id just like to ask you, listeners of Rest of Science, why are you watching this episode on now? if not a black mirror of our own modern invention. You know? Wha, Look how you tied that back to the show. A Little cheesy endick for you though. Hannah, thank you for telling me about Obsidian today. I didn't know any of this stuff. I just thought it was like a neat rock Probably a mineral. I was one of those Mineral believers and now I know it's a mineraloid. I think mineraloid sounds a bit like an insult ye Yeah, mineraloid Yeah, you didn't quite make it to be a mineral. And yet, when it comes to rocks, that's a pretty cool property to have. That is a pretty cool property to have. All right, well that's it for this week. As ever, you can send us your questions. The rest is science at goalhanger. com or leave a comment under this video on Spotify or YouTube or wherever you're getting this, we actually frankly, Read way too many of them normally at two o'clock in the morning when I can't sleep. that's my habits. Yeah, so talk to us Give us some late night reading, leave a comment, and we'll see you next time Absolutely. Byee There are two types of business owners Those who are busy and those who want to be busy. Toast is designed for both with tools to keep you humming and help turn grind into growth. That's how you turn busy into business. Tast built for busy. 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