Man made black holes, low energy vacuum bubbles, strange lits. These are some of the ways that an ill conceived physics experiment could pose an existential risk, not just for humanity, but for all life on Earth and possibly for every atom in the universe if things go particularly badly. Physics experiments seem like an unlikely place to find a clutch of existential risks, but it makes sense. Really. There are no other branches of science that explores the places where something is magic. Is accidentally creating a tiny black hole could happen. Physics is the purest branch of science. Back in the thirties, physicist Ernest Rutherford put it something like all science is either physics or stamp collecting. Physics, in particularly particle physics, is the place where the leading edge of science explores new frontiers of the universe. It's as literal as that. But we are still at an early spot in our understanding of particle physics, in the place in human history where you and I live. Now, those forays by the leading edge of science are blind pokes in the dark, and we face a dilemma because of this. We can't understand the universe without poking at it, but we can't really say if poking at it is safe until we poke it. The idea that particle physics could end the world sounds like nothing more than paranoid fantasy, born from something like fear of science and it's big, hulking machines that blast invisible particles into one another, but concerned that dangerous exotic stuff could be created inside a particle collider come from the physics community itself. Physicists are aware that they know enough about physics to build machines that can simulate nature, but don't know enough to say for certain just what will happen inside those machines. We don't know enough to know that those experiments were running are existentially safe, but we're doing them, pushing the envelope anyway and hoping for the best. To understand how things like low energy vacuum bubbles and man made microscopic black holes could accidentally be made here on Earth, you have to know a few things about physics first, and I will tell you everything you need to know. To start, I'll need you to hold your hand up in front of your face. I want you to focus on, say, the back of your hand. Hold it up in front of you. Gaze upon it, kind of lose yourself in it. Let your eyes come in and out of focus, so that your hand becomes the only thing in the world. Now, find some little spot on your hand and focus on it. Let your self be drawn into that spot, drawn into your hand. As you travel into that tiny point on your hand, you will grow smaller and smaller and smaller, so that you can pass easily through your own skin, past your bone, and into your veins, further and further inward, growing smaller as you descend, shrinking through your blood and plunging into one of the giant, gummy disc red blood cells in it, growing smaller and smaller, so that you pass right through the cell walls untouched, smaller and smaller among the galaxy of a hundred and twenty trillion atoms that make up a single red blood cell. Plunging into the electric cloud that envelops one single fuzzy oxygen atom, you are surrounded by the electrical field, like a fog that encapsulates the nucleus and binds the electrons to it A million miles away. Here inside the atom, you will learn the truth of the universe. Everything looks different than what you've always learned in school. There is no atomic solar system, with the nucleus as the sun and the electrons like planets in orbit. The electrons are everywhere and yet nowhere at once and at the center. There is no proton, no neutron. There are no particles like tiny pieces of matter, like crumbs of the universe. There are only vibrations of energy. These are the true building blocks of the universe, the corks and the gluons and all of the other elementary particles that make up everything that the material world is built from. You are here in the quantum world, and now that you look around, you see that there are vibrations everywhere. All around you, you see fields of different kinds of energy passing through each other, interacting with one another. And within those energy fields are countless moving, pulsating vibrations. Look back upward, now up from your place in the quantum field, pass the atoms to the cells and out of your hand. Look up to your own face and to the sky and the sun behind you. All of those things, you, the sky, the sun are made up of spectacularly complex arrangements constructed from the energetic vibrations of complimentary force fields, entangled by irresistible forces until time runs its course for them and their arrangement collapses when they break down and travel along their fields until they are attracted into some new arrangement. From a frog as it dies, to the algae of a pond that decomposing, to the belly of a fish, to the mouth of a mother, to the iris of a newborn child. The cycle of life and death is nothing more than the movement of energy along a universe of force fields. You can see now that everything, every site you've ever seen, everything you've ever touched, everything you've ever smelled or tasted, every emotion you've ever felt, all of it is made from the interaction of the energy fields that make up our universe. Even you, you can see now that you are a bundle of discrete vibrations held together by attractive forces in the hyperlocal area of the universe that until a few moments ago you always thought of as your body. Pinch your thumb and your index finger together tightly. The sensation of pressure that you feel, there's nothing more than the electromagnetic force pushing back against itself. Physicists have known all of this for more than a century, and now you see the true nature of the universe. Every thing is energy. All of the vibrations in the universe, and so all of the matter in the universe are remnants of the energy left over from the Big Bank. Almost every vibration unleashed, and the first trillions of a second after the Big Bank came in equal and opposite pairs, and they canceled each other out. They annihilated each other, almost all of them, but not all. This is Don Lincoln. He's a physicist at Fermi Lap near Chicago. Very early on in the universe, there was some asymmetry, some little difference between the two of them. And what happened is there was a very slightly larger number of matter vibrations than antimatter vibrations, something to the tune of three billion to three billion and one. And then the three billions canceled and the one was left over. And that's the matter of abrations that are left that make up the what we see now in our universe. Why there is something and not nothing is one mystery that particle physicists have run across while plumbing the void. Another is exactly where our universe came from. It's looking increasingly likely that there was nothing that came before that our universe erupted randomly from an aberration in an energy field, like a bubble of steam rising in a pot of boiling water, and in fact, the basis of a theory by physicist Roger Penrose from Oxford University called conformal cyclic cosmology, says that this is just the way that universes are formed. One bubbles up, lives, dies, and leaves nothing behind but the remnants of the black holes that formed in it, which are scooped up in the structure of the next universe that bubbles up to replace the old one. To us living in this universe, such a process would take the longest scales of time a man tenable, but to someone with a different perspective of time, perhaps watching universes bubble up, collapse, and bubble up again might be like watching a pot of water simmer. All of this is to say that if our universe arose from an aberration in an energy field, or from the remnants of the collapsed universe that came before ours, then it could happen again. Our universe could be reborn in a different form within itself and from a closer look at the Higgs field, it appears that it's constantly trying to do just that. One of the energy fields that make up our universe is the Higgs field. It is the field that gives mass to other energetic vibrations. Without the Higgs field, nothing would have mass, which means that the Higgs field is the energy field that allows you and all other matter in the universe to physically exist. Without mass, there cannot be matter to be bound together, and without matter, there cannot be chemistry, which binds that matter together and creates new forms of matter. And so without chemistry there can be no life, which means without the Higgs field, there can be no life, which is one reason the Higgs boson. The particle that carries the energy of the Higgs field and interacts with other particles, is called the God particle. The other reason is that God particle was originally short for the God damned particle, which is what physicists called it because it eluded them for so long. It seems a bit heavy, but think of mass is just another property that a vibration can have, like how a ball can be read, round and bouncy all at the same time. When you know what properties of ball has, you can predict what it will do in any given situation. Like if you drop the ball, you can say that it will probably bounce a couple of times and then roll away. And since it's red and round, you know what to look for when you go try to find it in the grass to get it again. The same goes for sub atomic particles too. Their properties, like their electrical charge and their mass, let physicists predict how particles will interact with particles from other energy fields. And since everything is energy, if you can understand how every energetic particle interacts, you can understand everything. And since Einstein showed the world with his E equals MC squared equation that mass and energy or just two sides of the same equal sign, you can just look at mass like it's just another type of energy, which it is. When a vibration arises, let's say a cork from the cork field, it interacts with the boson from the Higgs field, almost like it's coded by it. And now that cork has mass, so it can be acted on by other fields like the gravity field. These fields, the cork field, the gravity field, the Higgs field, all of the fields, they are everywhere, at every point in the universe. The Higgs is the only field that can give mass to other vibrations, and it has another unique property too. It is the only field that still has an energy when it's turned down to zero, which is surprising. If you could turn down all of the energy fields in the universe to zero on some master universe style, there would be no electrons at all in the electron field, no corks, no glue ons, all of the energetic vibrations would cease, and yet energy would still persist in the Higgs field. It's like if you turn down the volume on this show to zero, yet you could still make out faint pops and crackles in your headphones. It would lead you to believe that there was some setting below zero that you could turn the volume down to. Well. Physicists have arrived at the same conclusion about the Higgs field, but this opens up an unsettling possibility. If the Higgs field isn't currently at its lowest energy state, and the Higgs field is what gives matter mass, then if the Higgs field ever slipped into that lowest energy statement, the mass of everything in our universe would suddenly change. In other words, we would all disintegrate. This is theoretical physicist Ben Schlayer from the University of Auckland in New Zealand. Particle physics and the corresponding chemistry would be suddenly very different, and in particular, matter would no longer be at the right size. The different sizes of the atoms that make up matter are based on the distance between the electrons and the outer periphery and the nucleus at the center. If electron suddenly got heavier, adams would shrink into smaller size, which means everything in our universe would suddenly shrink. All of the matter around us would suddenly find itself unstable to a great shrinking, and as it shrank, it would give off a huge amount of electromagnetic energy. So they'd be an explosion of X rays and that would be a pretty violent event. Two theoretical physicists, Sidney Coleman Frank DeLucia determined back in that this new lower energy state of the universe would not support chemistry, which means that life would not have the chance to re evolve in this new version of our universe. They called this vacuum decay and said that it was the ultimate ecological catastrophe. But things can actually get worse from there because the shrunken universe is denser than it was before. That means gravity acts on all of the mass throughout the universe more forcefully, too, so that vacuum bubbles outward. Expansion will eventually be and then reversed as it's pulled backward, returning to where it started, like an implosion, forcing all matter into an infinitely dense, infinitely tiny ball, possibly the very same place where our universe started from. This is called the Big crunch. It's the antithesis of the Big Bang. Spacetime ends and the universe ends. In a big crunch, it would be like our universe never happened. That the Higgs field has balanced between its current state and the lower energy version of itself means that it poses a natural existential risk to us. If it moved into that lower energy state, that would be it for not just human existence, but for everything in the universe. So the Higgs field actually poses a universal existential risk for now and for the foreseeable future. At least, the Higgs field is in a state called meta stable. The good analogy is a puddle in a valley at the bottom of the hill. On the other side of the hill, say there's an even lower valley, and the Higgs puddle would be happy to settle into that lower one. But it would take a tremendous amount of energy for the puddle to move itself up the hill to the other side, energy that the puddle doesn't have, so the Higgs field won't be moving up the hill. But there's another way that it could slide into that lower energy state. Unnervingly, the Higgs is constantly trying to tunnel through that metaphorical hill to get to the lower valley on the other side, and this attempt to tunnel through comes in the form of indescribably small pockets of this other lower energy version of the Higgs field that at every moment bubble up from it like a simmering pot. But these lower energy Higgs bubbles are too weak to overcome the external pressure or universe exerts on them, so they wink out of existence just as fast as they arise. The trouble is that if one of those lower energy bubbles ever does manage to stick around long enough to stabilize and grow, it would swallow our universe and bring about that vacuum decay that Coleman and DeLucia wrote about and disintegrate our version of the universe. It would be a big crunching deal, you could say, But probability is on our side. Under normal circumstances, the chances of one of those lower energy version bubbles growing are so low it's not expected to happen over the estimated lifetime of our universe, so we appear to be in the clear again. Though that's under normal circumstances. We humans have a tendency to alter normal circumstances, and there's a way that the Higgs field campose an anthropogenic existential threat. A vacuum bubble could grow with the help of a microscopic black hole, which we might actually create. Inside one of our particle colliders. Here on Earth, m about a hundred meters beneath the countryside where Switzerland juts up from the southeast into France. Above sits the Large Hadron Collider, the largest highest energy particle collider in the world. Hadron is a name for sub atomic particles like protons and neutrons that are made up of quarks and gluons. Those energetic vibrations that make up matter. If you could go inside the LHC reduce yourself back again to the scale of those energetic vibrations, you would see something spectacular. The protons in the Large Hadron Collider are created by passing a laser through a cloud of hydrogen gas, which breaks the atoms apart. Those stripped protons are directed into the LHC's vacuum tubes by an electrical current, and they're separated into two beams that are kept apart and sent in opposite directions around the elliptical collider. Over the course of days, the beams are accelerated until they reach unimaginably fast speeds point nine nine nine one percent the speed of light, where a single proton can make the trip around the seventeen mile circumference of the collider more than eleven thousand times in a single second. At these speeds, the protons carry with them as much as five trillion electron volts of energy, an extraordinary amount for something so small. It's like a mosquito with the kinetic energy of a planet. When the beams are at their highest speeds, they're directed into each other so that they cross inside of one of the collider's enormous sensitive detectors. Every second a billion collisions take place, and the energy from those impacts turns into mass, which creates particles for just a fleeting moment that we're around right after the Big Bang. So the LHC is a way to rewind nature, to study its origins. To me, it's like I think of using particle colliders to understand the universe as an exploration. We're like looking for new stuff and you never know what you find. You know, this is particle physicist Daniel Whiteson from the University of California, Irvine, And one strategy we have to understand these things is just to look for patterns among the particles. And the way to look for patterns is to see more of them. That's the goal of using the LHC to explore the universe. We want to find more particles, get more clues, see sort of a larger window into the reality that we're seeing currently, and hopefully get some insight. The Large Hadron Collider was first brought online in two thousand nine after decades of planning and construction, and it woke up in a world where the field of particle physics had hit a wall. The LHC was designed to break through that wall. It was designed, you could say, to break physics. The work of particle physics can be divided between two groups. On the one hand, you have theoretical physicists. They come up with all the ideas about how the universe might work, and on the other hand, you have experimental physicists who test those ideas in machines like the Large Hadron Collider. The work of these two groups forms in aura borros, the mythical snake that eats its own tail. The experimental physicists find support for the theoretical physicist theories, or they say that they're wrong. The experimental physicists also come up with new data that the theoreticians can use to create entirely new theories that the experimental physicists can then test. As a deeper understanding of particle physics develops, the snake grows fatter. In the nineties, sixties and seventies, the theoretical physicists dropped a huge amount of new work on the desk of the experimental physicists. A group of theoreticians wrote down everything science knew about the quantum world and What they came up with is a set of formulae known as the Standard Model of particle physics. Over the decades, the Standard Model has been proven correct again and again. The Standard Model does a really good job at describing the particles that exist in the quantum world and the forces that govern them. The strong nuclear force binds protons and neutrons into the nucleus of an atom. The weak nuclear force causes atoms to decay over time. The electromagnetic force binds atoms together into higher structures like you and meat, and the sun, and mosquitoes and red blood cells. Every particle that the Standard Model predicted should exist by now has been discovered. It is, as scientists put it, an extremely reliable model to describe the quantum world. The last of the bunch was the Higgs boson, which the LHC found in two thousand twelve, and with that discovery the experimental physicists exhausted the theoreticians standard model. But as good as the Standard Model is, as reliable as it is, it's been incomplete from the very beginning. It has no place for gravity, and vice versa. With Einstein's famous theory of relativity. It's proven extremely reliable at describing how gravity governs the interaction of large scale things like people and planets. But the other three fundamental forces, electromagnetism and the weak and strong nuclear forces don't fit into the equation partum field theory. It really doesn't deal with the universe as a whole, and it's well known that general relativity does not merge in mill well with a quantum realm. So what physics has on its hands are the standard model and the theory of relativity too totally accurate but totally incomplete pictures of the universe that won't fit together to form a cohesive whole. It's almost like they repel one another. Particle. Physicists built the large hay Drown Collider to figure out why that is. They hope that the incredibly high energy collisions will produce new particles that don't fit into the standard model to show where physics should start looking next. One of the biggest mysteries of all that physicists are hoping to solve is why gravity is so weak compared to the other three fundamental forces. It's strange. Gravity is the force that keeps planets in orbit around massive stars and can catch light by the ankles and prevent it from escaping a black hole. Yet the other three forces are stronger, and you can see this for yourself if you just lay a paper clip on a countertop and hold a regular old refrigerator magnet over it. As you bring the magnet closer, the paper clip will eventually rise to meet and stick to it. What you've just seen is the electromagnetic force and that tiny magnet overcoming the gravitational force exerted by the entire mass of planet Earth. Like I said, strange. To make sense of this, and to unify relativity in the standard model into a theory of everything, some physicists have taken to adding new dimensions to our universe. Some models see our four dimensional world of length, with height and time as just a tiny membrane floating within an infinitely larger fifth dimension that we can't sense, called the bulk. Others include as many as eleven total dimensions, most of which are curled up into extremely tiny coils at the corners of every point in the fabric of spacetime. These models explain why gravity is so weak by allowing it to spread across all of the dimensions. The other three forces, like us are trapped within our four D world, but gravity is not. And if we could sense all five or eleven, or however many dimensions there are, we would see that gravity has the same strength as the other three forces. It just seems weak to us because it's diluted by comparison inside our four D world. So one way that physicists are hoping that the LHC breaks physics is by revealing the presence of other dimensions. And a really good way to demonstrate that there are other dimensions would be to create a microscopic black hole. Those aren't supposed to exist in our four D world until the idea came along that's such a thing as microscopic black holes could exist. We used to think that we understood black holes pretty well. It was sort of a golden age of black hole understanding. We learned over time that black holes were gaping, all consuming, horrific abominations in space time, with masses so huge that they boggle the mind. Sure, but we could feel good about them. We understood them, and we were here, and they were a way out there. They had no way to touch our world, let alone end it. From studying them, we found that black holes were created when some incredibly massive star far larger than our Sun, exhaust at its fuel and collapsed under an unimaginable force of gravity into an infinitely dense, smaller version of itself that actually pushed a bottomless pit in the fabric of time and space. Encircling the rim of this black hole is the event horizon, the threshold where the gravitational poll is so strong that anything crossing it is doomed to be forever trapped inside the black hole, torn apart by the unimaginable gravity with it. Over time, we began to notice black holes everywhere we could detect them, ripping apart nearby stars, pulling them into a ring of hot gas, and circling the event horizon like water around a drain. We began to find them at the center of galaxies, including our own Milky Way, which nourishes a monstrous, supermassive black hole the size of four million of our sons. We saw that black holes could cannibalize other black holes, which forms even larger black holes, and perhaps the fate of our universe was to one day be swallowed into one giant black hole made up of every black hole that's ever existed in every universe that's ever existed, But like any good golden age, this one was not meant to last. It ran from the time black holes were predicted in Einstein's theory of relativity in nineteen fifteen until about the mid seventies, when a not yet world famous physicist named Stephen Hawking proposed some ideas about black holes that suggested that maybe we didn't understand them so well after all. For starters, Hawking and his colleagues proposed that black holes didn't have to be made of something as big as a star. Black holes could actually be incredibly tiny. This was news. It's true that anything with mass can be turned into a black hole if it's made dense enough. If the Earth were condensed to do a black hole, it would have an event horizon about as big around as your index fingernail. But as far as physicists understand it, the Earth could never actually become a black hole because it simply doesn't have enough mass for gravity to collapse it into that infinite density. It takes a truly sincerely massive object like an enormous star to undergo that sort of transformation. What Stephen Hawking and his colleagues realized back in the seventies is that there are actually times in the universe's distant past, say within trillions of a second after the Big Bang, when everything was much much denser, and so during this time, something with a mass like the Earth's could have collapsed into a black hole back then, and much much smaller things could have two, maybe even particles. Hawking called these hypothetical particle sized black holes that may have formed in the very early universe primeval black holes. Today people call them microscopic black holes. In addition to his theory that such a thing as very tiny black holes could possibly exist, there was another thing that Hawking realized that brought our golden age of understanding black holes to an abrupt end. It was actually possible for them to spit matter out. He said this was news too. Our understanding of black holes at the time was that they did nothing but consume, ceaselessly, growing eternally. The idea that they could spit stuff back out was pretty revolutionary. The idea that black holes could actually radiate energy came to be called appropriately Hawking radiation, and Hawking showed that a black hole could emit photons and gravitons, the particles that carry electromagnetic energy and gravitational energy, respectively. Normally, these particles don't have matt mass, they don't interact with the Higgs field. But what Hawking figured out is that the less massive a black hole is, the hotter the temperature of the radiation that it spits out, which means a very very tiny, microscopic black hole with a very very small mass would actually have extremely hot radiation because its mass is so small that radiation could be hot enough. Hawking realized that the photons and gravitons the black hole spit out could actually have mass themselves. And here's why temperature is a measure of heat. Heat is a form of energy, so high temperature means high energy. And since mass and energy are two sides of the same coin, E equals mc squared. Remember, mass and energy are theoretically interchangeable, which means that heat can be translated into mass. Another way you could put it is that if the energy of a normally massless particle like a photon or a graviton has a high enough energy, it will interact with the Higgs field and get coated with mass, and a microscopic black hole could produce photons and gravitons with energies that high. If Hawking was correct, then that means that over time a tiny black hole could actually lose mass itself as it spit out photons and gravitons with their own mass, and at some point, when the microscopic black hole lost enough mass, it would wink right out of existence. Black Holes aren't supposed to do this. It seems we didn't understand black holes nearly as well as we thought we did. Are comfortable Golden Age came to an end. It's about here where the story begins of how cern, which actively messes with the mass and energy of particles, took up a long time quest to prove that it's large hadron collider won't do humanity. Actually, wait, it begins a little before the LHC came along. The story really starts. In that year was, as far as anybody knows, the first time anyone seriously raised the idea that a particle collider might be able to end the world. Scientific American Magazine published a letter from a reader who wasn't so sure that the relativistic heavy ion Collider at the Brookhaven National Lab in New York nicknamed the Rick, was entirely safe. The reader was concerned that the rick might produce a microscopic black hole, the kind of thing that Hawking proposed, when particles collided inside of it. Scientific American published the reader's letter along with a response by a physicist named Frank will Check, and will Check pointed out classical six doesn't allow for microscopic black holes to exist at all. That's point one. Point two was that even if the theories that include additional dimensions, theories that are beyond classical physics and actually do allow for microscopic black holes to exist, if those additional dimensional theories turn out to be true, the energies of the particle collisions in the rick were still far too low to actually create a microscopic black hole. So no worries, Well, there was one worry. At least. Will Check did mention that it was much more likely the Rick could produce an exotic type of matter called a strangelet. Strangelets are heavy particles made of smaller vibrations called strange quarks. Despite their heavier size, they're actually lower energy than typical strange quarks, which means that the universe would prefer them over strange corps. It's just that strangelets tended as all very quickly because of their higher mass. The concern over strangelets is that if one of them didn't dissolve into elementary particles, it could conceivably set off a chain reaction, lowering the energy but increasing the mass of the matter that makes up Earth, converting our planet and everything on it, including us, into a massive, inert dead bulk. Will checks offhand comment at the end of his reply set off a separate, years long tangent of uneasiness and investigation into strangelets and whether they have the goods to pose in existential risk themselves. But at least the microscopic black hole terror was put to bed, or so it seemed. The terribly disconcerting idea of a man made black hole has a habit of winking into existence again and again. A couple of years after the Scientific American readers black hole question was asked and answered, the looming specter of a potentially world ending black hole created in a particle collider rose again, like a new universe rising to replace an old one. This time the collider in question was the Large Hadron Collider, which was beginning to be assembled in Europe. This time around, the fears weren't quite so unfounded, because the energies of the collisions in the Large Hadron Collider are an order of magnitude higher than the ricks, high enough, in fact, that if any of those multidimensional theories are correct, the LHC should be fully capable of producing microscopic black holes inside of it. So capable, in fact, that a two thousand one paper by physicists Stephen Gettings called the LHC a black hole factory and calculated that it could produce a microscopic black hole every second it's proton beams were crossed. Now it's here where CERN began its long standing quest to prove the Large Hadron Collider is safe. On the one hand, the idea that the LHC might be able to break open the current understanding of the universe and point theoretical physicists in a clear new direction is intensely exciting for the particle physics community. But on the other hand, CERN was much less excited about the idea of everybody else seeing their machine as a black hole factory that could end the world. And it's pretty easy to understand why the funding for certain at any given point is precarious enough under the best of circumstances, they count on public funds from multiple nations and work under the threat of those funds drying up at any time, and the stakes for keeping the Large Hadron Collider funded are very high. This is law professor Eric Johnson, who has written extensively on the risks that come along with high energy physics experiments. It's really hard to downplay the amount of money and the amount of professional lives that are involved with the Large Hadron Collider. Uh. CERN is a multibillion dollar institution. UH there's thousands of people who work there and in the field of particle physics. In the field of particle physics, there really aren't It's not like everyone's off doing their own experiments. Particle physics tends to be dominated by the big collider of the day and the data that it's producing. And if that collider doesn't come online, then there's nothing to study for a whole lot of people. Protecting certains enterprise is made all the more difficult by the fact that what it is doing is pure science. There's no obvious research and development that can be turned into useful products that the nations involved can expect to make back some of their investment with instead. The LHC is as unadulterated as scientific experiment as you will find on Earth. It was designed and built solely so that we can better understand the universe in our place within it. A genuine, noble public good to benefit all humankind. It can be tough to make money off of else. That is not to say that the Large Hadron Collider hasn't already produced dividends well beyond physics. You could argue and plenty do. That's certain paid for itself many times over. Back in the late nineteen eighties, when one of its computer scientists, a British man named Tim berners Lee, created a method for linking text files so that they could be shared universally over computer networks. Burners Lee called it the Worldwide Web, so that it could protect its funding, calm fears among the non scientific public, discover whether the LHC actually is an existential threat or all of those things. CERN took up its quest to demonstrate that the Large Hadron Collider will not doom humanity, who would be a long and circuitous route so at that point cern couldn't rely on the not having enough power to produce black Hall's argument for safety, and they they acknowledge the need for a new examination of hazards, and uh they went back and did some new work on that, and then they said in two thousand three that Hawking radiation will ensure that any black hole that's produced will evaporate almost as soon as it's produced, so that that will be safe. Because any microscopic black holes the colliding particles inside the LHC might manufacture would have extremely small masses. Hawking radiation says that they would emit particles and lose their mass at a blinding speed, winking out of existence instantaneously. Just how fast that would happen, called the rate of decay, would be a fraction of a fraction of a second, something like ten to the negative power of a second, a decimal point, followed by zeros, and then finally all the way down in the position a single one that fraction of a second. In this unimaginably short time, the microscopic black hole would have no chance to absorb any matter and grow larger. On this infantism le small scale matter is just too few and far between, so the microscopic black hole would be gone before we knew it was ever there, but it would leave telltale traces behind that the LHC's detectors could find and show the world that there are dimensions beyond our own. But this argument that suggests the Large Hadron Collider is safe comes with some baggage. Between the time that the research began on the safety paper and when CERN released it, the physics community's faith in the existence of Hawking radiation was shaken. In the early two thousands, the trickle of papers began to question it. It wasn't disproven, just question enough to erode it as the kind of thing that CERN could fet the survival of the planet on. So CERN looked for another way to show the Large Hadron Collider was safe, and this time they settled on cosmic rays. Cosmic rays aren't exactly what they sound like. They're actually tiny energetic particles that travel at incredibly fast speeds through space and smash into other particles, creating a spectacular cascade of energy converted temporarily into mass. And if this sounds a lot like the collisions inside the Large Hadron Collider, you're absolutely right. A particle collider is, if anything, a laboratory for stimulating cosmic ray collisions, and because they're so similar, means that since cosmic rays bombard everything in the universe all the time and have for billions of years, then the fact that the universe still exists proves that even if particle collisions can create microscopic black holes, that microscopic black holes must be harmless, because again, the universe continues to exist. That is the cosmic ray argument, and it's the second thing that's certain pinned the safety of the Large Hadron Collider too. But there's a problem with the cosmic ray argument as well. Cosmic rays aren't exactly like particle collisions inside the Large Hadron Collider, and exactness is kind of important when you're trying to show the world that your machine won't bring about the end of the universe. Cosmic rays travel at high speeds, yes, but the particles that the cosmic rays smash into, say particles in the Earth's atmosphere, are just kind of hanging out there. They're relatively stationary, which means that the collisions are a lot like rear end collision and most importantly, in a rear end collision, the momentum of the faster vehicle or particle carries it and the other vehicle or particle careening off in some direction away from the site of the crash. This is important because it means that if cosmic rays do produce microscopic black holes, the momentum of the crash would carry the microscopic black holes away from the collision to most likely they'd pass harmlessly through Earth and right out into outer space. The problem is in a particle collider, the collisions are different. They're less like rear end collisions and more like head on collisions, and then a head on collision, the two particles cancel one another's momentum out when they collide, they don't go anywhere. The upshot of all of this is that a microscopic black hole produced by the collision wouldn't go careening off away from the impact and into outer space. It would be stationary. It would stay put, which means that it would stay put here on Earth. That is a problem because if we've already thrown out the idea of hawking radiation, and along with it, the concept that a microscopic black hole would simply wink right out of existence if it was created, then that means that if we do create a microscopic black hole in a particle collider, it would hang around here on Earth, which means that it could possibly grow, which means that it actually might pose an existential threat to us. As far as safety arguments go, this is decidedly not reassuring, especially considering the idea of the two thousand one paper by Stephen Gettings that said that the LHC is a black hole factory. If that paper was correct, then a new, stable, earthbound microscopic black hole is created inside the collider every second it's proton beams are crossed. So certain looked again for a new way to show that LHC was existentially safe. What they needed was something out there in the cosmos that was dense enough to have a gravitational pull that could hang to do a microscopic black hole. Something that could do that would show again simply by existing, that microscopic black holes really are harmless. It would show that even if the Large Hadron Collider produced a microscopic black hole and the Earth hung onto it, there's still no cause for concern. It was basically cosmic ray argument two point out, and CERN finally found what they were looking for in white dwarf stars. A white dwarf is a star that's run out of fuel and has partially collapsed, so it becomes far denser and exerts a much stronger gravity on things around it, definitely more than Earth's gravity. So any microscopic black holes that a rear end cosmic ray collision could produce would still be stuck in the star that wouldn't careen off into outer space. And since white dwarfs are bombarded with those cosmic rays, and since they enough gravity that they could trap a microscopic black hole, then the fact that they continue to exist strongly suggests that microscopic black holes are not a danger. That is to say, again, if microscopic black holes even exist. Based on astronomical measurements of white dwarfs, CERN found eight of them that, in their opinion, were dense enough and old enough to sufficiently demonstrate the safety of the large Hadron collider certain issue of paper, and it was followed by another paper that concluded the first paper was sound, and they circulated both papers to the physics community, which in turn provided CERN with quotes about just how sound the conclusions of the papers are and just how utterly safe they show the LHC to be. Certain included these quotes on their website, and that's where things stand today. Classical physics, which represents our current understanding of physics, doesn't allow for microscopic black holes to form in the place. But even if those microscopic black holes could form, so long as those eight white dwarfs exist in the sky, Certain is willing to bet the whole farm on the safety of the LHC. But with physics, our understanding has a way of changing. The whole idea of particle physics is to discover new things. Particle physics works at the leading edge of human knowledge, at the leading edge of theory. That's the whole point of it is to be out there trying to figure out something new. So it does evolve all the time. And I think it would be naive to say that right now this year, we've arrived at a point where the theory is not going to change, or the assumptions are not going to change, so that we can feel satisfied that whatever conclusion particle physicists have today about the safety of a particle accelerator that that's not going to change m M. By now, you might be asking yourself exactly how might a black hole be created inside the large Hadron collider? Well, that is an excellent question. When you take a little tiny particle like a proton, and accelerated to almost the speed of light, something very peculiar happens to it. The little amount of mass that it has starts to grow, and as its mass grows, the stronger the gravity acting on it grows too. A very fast particle accelerated in the Large Hadron Collider begins to grow enough mass that it warps the fabric of spacetime around it. This warping has the effect of concentrating gravity, and in the minute fraction of a moment before two extremely fast moving particles collide, they're bent gravity's over lap and concentrate gravity even further. The sum of all these parts amounts to an unusual amount of mass and extremely high gravity concentrated within a very very tiny area. All of this together could produce a microscopic black hole. Because it would lack the kind of escape velocity that a cosmic ray might give it. The microscopic black hole would be held fast by the gravity exerted by the Earth's mass. About every half hour, the microscopic black hole would oscillate between the LHC and a point on the opposite side of the world, somewhere off the coast of New Zealand, and back inside the Earth. The black hole would grow over time, but exactly how long that process would take depends, as does everything, it seems like, on the correctness of one of the unifying theories that combine relativity with the standard model. One of the things that's so unsettling about the idea of Hawking radiation, the theory that a microscopic black hole will wink right out of existence just as fast as it's created, is that whether Stephen Hawking was right or wrong, microscopic black holes still pose an existential risk. If Hawking was wrong and there is no such thing as Hawking radiation, then a microscopic black hole could stick around and slowly eat the world. What would a black hole eating the Earth from the inside out look like, Well, it's hard not to imagine a microscopic black hole growing in the Earth's core until it emerged on the planet's surface, kind of popping out as a gaping bottomless pit that some hapless person wandering through the woods might accidentally stumble into. But this isn't what it would look like at all. Remember, if the Earth itself could be compressed into a black hole, it would have an event horizon just about a centimeter in diameter, So any microscopic black hole that consumed all of the Earth's mass would have an event horizon about the same size. A microscopic black hole then would never pop up on Earth's surface. It would still be unnoticeably tiny as it tore the planet apart. Plus, let's not forget we couldn't see it anyway, being a black hole, like couldn't escape it, so it couldn't reflect off the black hole's surface, which would make the microscopic black hole both tiny and invisible. But we would be able to clearly see the effects it had as it tore our planet apart. One of the defining traits of a black hole is, of course, the intense gravitational pull that it exerts on matter around it. Black Holes are capable of pulling matter literally apart, and as it does, it releases enormous amounts of energy. That violence produces extremely high temperatures and all of that hot torn apart matter becomes trapped in an orbit around the black hole. Eventually that matter falls past the event horizon, unable to escape. Particles that the microscopic black hole encounters in the quantum world would be among its first victims. But as it grows over time, the black hole would eventually get big enough to devour whole atoms. And as the black hole grows, so too will its strength. The more it increases in mass, the more of the Earth it will draw into it, pulling Earth apart and into that gaseous stew of hot matter that circles around it. Over time, the magma, the bedrock, the soil, the lakes, the very planet itself would be pulled apart. There would be no place left for life to live on Earth, which would be a moot point anyway, since every bit of life on Earth would be pulled apart as irresistibly as the planet itself, drawn into that roiling circle of plasma around the black hole, which would slowly feed on our planet for a very long time. Under classical physics, the time it would take for a tiny black hole produced in the LHC to gain enough mass to become a threat to life on Earth is longer than the current age of the universe, more than thirteen billion years, but that time shortens dramatically when new dimensions are added. The additional dimensions allow for stronger gravity on those quantum scales, which would allow a microscopic black hole to attract and consumed particles early in its life much more quickly. Such a black hole could destroy the Earth in as little as three hundred thousand years, which is a bit alarming considering the possibility the LHC has been creating a microscopic black hole every second it's been colliding protons to as it came online back in two thousand nine. Humanity might still very much place a high value on our home planet a few hundred thousand years from now, and prefer that it continued to exist. It's probably a good bet that our descendants would not want the planet ruined by haphazard physics experiments conducted by their ancestors. I imagine the rest of life on Earth would have similar feelings on the matter too. But what if Hawking was right and microscopic black holes do evaporate, It could still pose an existential threat because in evaporating microscopic black hole could give a low energy vacuum bubble from the Higgs field just the boost it needs to grow and ruin the universe. If we can rewind back to the moment in the LHC when those two particles collided head to head at amazing speeds and they're concentrated gravity overlapped, Let's say that the microscopic black hole they produced didn't grow up to tear Earth apart, but instead it evaporated, just as Stephen Hawking predicted. As it evaporated, it could become the nucleus for a low energy vacuum bubble to grow, in a very similar way to how tiny impurities in a metal pot become the places where water can undergo a phase transition from liquid to gas within itself. This is what we call forming a bubble. An evaporating black hole could serve as a nucleation site for the Higgs field to undergo a transition from its current state to the lower energy version of itself, which again would bring about vacuum decay, the ultimate ecological catastrophe, which, again, at the risk of restating the obvious, would be very bad for the current arrangement of our energetic vibrations. This would not take a few hundred thousand years to notice. It would happen so fast that we likely wouldn't notice we just suddenly be gone. So we have then at least two possible catastrophic outcomes from the creation of man made microscopic black holes here on Earth. And what's unsettling about them is that there's a catastrophe for each possibility. Where Stephen Hawking was either right about evaporating black holes or where he was wrong. Take your pick. One day in two thousand and eight, a bird that lived in the countryside along the border between Switzerland and France found itself a bit of crusty bread. Around that same time, one of the electrical supply stations that cools the Large Hadron collider's magnets with liquid helium suddenly went offline. When workers went to investigate, they found a bit of crusty bread and some feathers. The press reported on it, took liberties with it, and that story grew to enormous proportions. Words spread that a single bird with some baguette had knocked out the Large Hadron Collider, the fastest and largest particle collider on Earth. A pair of theoretical physicists named Hulger Nielsen and Massao Ninomia had been taking note of the accidents in weird setbacks like this that plague the LHC as it was being built. They had come to believe that something, possibly God, was reaching back from the future two sabotage the Large Hadron Collider and prevent it from ever reaching full power. It might mean that the LHC would create something, the physicists said, that could destroy the universe. They took the bird in the baguette as further evidence for their hypothesis. Nielsen and Ninomia proposed issuing a challenge to the future to determine if we should shut down the Large Hadron Collider and abandon it forever. We could present the LHC with some luck of the draw, maybe something like ten million cards, all of them hearts, except one, just a single spade. And if we asked the Large Hadron Collider to pick a card, and the Large Hadron Collider picked that one single spade, an extraordinarily unlikely event, then the particle physics community should take it as a sign that the future was communicating a warning to us. Sir, never took the physicists up on their card draw proposal. Nielsen and Ninomia suspected that the future was trying to prevent the Large Hadron Collider from creating a Higgs boson, that particle that gives everything that has mass mass. It was widely hoped. In fact, it was largely the reason it was built that the LHC would produce the Higgs boson, which again was the last undiscovered particle predicted by the standard model. And in two thousand and twelve, the Large Hadron's computers found something that had been created for a fraction of a fraction of a second inside the collider that fit the parameters for the Higgs boson. There was no catastrophe, The world didn't end, and to an extent, the discovery of the Higgs frustrated physicists even more since it further supported the stubbornly accurate Standard model they've been hoping to break. But finding reassurance in the survival of the universe after the successful creation of the Higgs boson in the LHC is actually a logical fallacy. Specifically, it produces what's called the normalcy bias. We tend to assume that because no catastrophe has befallen us, yet none will. It's the same false belief that drives investors to buy stock based on past performance. But any financial advisor worth their salt will tell you there is no certainty about the future to be found in the past, and so too will a particle physicist tell you that. One of the tenets of quantum physics is that there is no such thing as certainty. We are incapable of certainty. Instead, particle physicists deal improbability. As one certain physicist explained it to me, you can, for example, take the number of times that a car's engine has ever been started and calculate the probability that the next time you start your car it won't create a chain reaction that ignites Earth's atmosphere. What you have, then is what's called the lower bound probability that it would happen in an odd, roundabout way. When cars were first invented, they actually had a higher probability of igniting the atmosphere compared to cars today, simply because fewer cars had ever been turned over back then. The large Hadron collider is in a similar position with the LHC. We simply have a smaller data set from the fewer times that it's been turned on. This is in a perfect analogy, though there aren't any quantum theories that suggest a car could ignite the atmosphere, like there are that suggests the LHC might be capable of creating a black hole or a strange lit But ironically, the more times we press our luck and run the LHC, the lower the probability that something terrible will happen. Get the thing is, no matter how many times we run the Large Hadron Collider, we will never be certain that something terrible won't happen. This is the curse of the universe that quantum physics carries with it. We are doomed to uncertainty. Eight white dwarfs still hang in the sky, but we still can't be certain that one of them won't begin to come apart tomorrow from the microscopic black hole growing within it. It's a matter of faith, faith, and probabilities when it comes to the existential safety of physics. Uncertainty curses. All of us physicists face a dilemma when they talk about the safety of their work to people like you and me. The general public. If they speak openly about it, they may cause a panic and possibly even undermine their own field of research. If they don't, they appear like they're hiding something. Here's physicist Daniel Whiteson again. And I think the reason is that they don't believe that there's a lot of and that there's a lot of numerous e in the public and in journalism, and that a nuanced position where you're saying, um, there's no none of the threats we understand are significant. However, there's a possibility of a thing we don't know that we hadn't considered that could of course destroy the world, but you know that's unlikely and unknowable and so not something to consider. That kind of nuanced position, I think it is very difficult to convey. So physicis systs may decide that the general public can't really understand probabilities, and we'll stop hedging when they speak about the safety of their work, erasing those remote possibilities of catastrophe and presenting a full certainty that particle physics is perfectly safe, that there is no risk. This is a dangerous position when it inevitably comes out that there is in fact a risk and that scientists are well aware of it. Trust is lost in the very people who carry out existentially risky experiments, and the most sensational and unfounded stories start to gain traction among the general public. And it's also directly a dangerous position as far as existential risks go, because existential risks are by definition remote. They are the risks that get erased when physicists speak with certainty about the safety of their work. But as you know by now, those same existential risks are the ones that can erase humanity should the ability surrounding an experiment suddenly skew towards the remote Unexpectedly. Pretending those risks are not there is the most dangerous route we can take. But scientists who do have the integrity to admit that they can't be certain their field doesn't pose existential risks frequently find that they're misquoted or misrepresented in the media, which can lead to them being ostracized by their colleagues for stirring up problems for the field. So they may become defensive, which is never good for keeping lines of communication open. But I think the experience of a lot of scientists is that they say Oh, that's very unlikely, but of course possible. And then they read an article where they say certain scientists says end of the world possible, you know, and so it's it's um, I think you're right that they're defensive, but I think that comes from some experience and some caution about the level of the discourse in the public arena. It is with this in mind that CERTAIN is to be commended for working to show that the large Hadron collider is a safe machine, even considering that it was a reactive procedure rather than a proactive one. CERTAIN is a great institution, and one thing that I admire so much about them is how open they are. And much of what I was able to do in my research is thanks to them being very open. They're very very open in terms of sharing their data, sharing their papers, being accessible in terms of talking to them. That's part of what makes me admire them so much as an academic myself. I just think that that's a great model for building and sharing knowledge, and it's to their credit that they have looked at these issues with a great deal of transparency. It is extremely important that the physics community follows CERN's lead and its willingness to investigate the safety of its work has their experiments grow more and more powerful in the future. There's a different interpretation to the cosmic ray argument, a more nihilistic one. It says that the presence of cosmic rays doesn't prove that particle colliders are safe. It just shows that our particle colliders can't make anything more precarious than they already are. Turning on a particle collider is safe because we can't turn cosmic rays off, so we're not going to be causing any new danger by turning them on. But what about some decades or a century from now, when our experiments begin to reach levels that exceed cosmic rays. If the Large Hadron Collider is an early incarnation of a long line of particle colliders to come, as physicists hope, there will likely be a point where the energies of future colliders rub up against and then eventually exceed, the energies of cosmic rays, the very same cosmic rays that we use today as some sort of proof that our colliders are safe. And over time, as physicists develop a greater mastery over the rules of our universe, particle colliders may transition into laboratories that physicists use to bend the laws of physics to their will. Those nearly blind pokes and prods into the darkness of our understanding that physicists today carry out are providing the body of knowledge that physicists to come in the future will build upon. And if humanity can survive our infro to physics, a tremendous amount of promise lies in store for us from it. An odd thing about the universe has been bothering physicists for a while now, and it's something that the discovery of the Higgs didn't help. It seems more and more that our universe appears to be finely tuned to allow for life to exist. The Higgs field, gravity, all of it is right within the narrow bounds that allow for atoms, chemistry, and life. When the Higgs boson was finally founded two thousand twelve, it appeared right in the very middle of where it was predicted, as perfectly finely tuned as the rest of the fundamental particles. One answer to the strange situation is that our universes finally tuned for life simply because of random chance. There's a remarkable implication of string theory, one of those theories that seeks to unify gravity with the quantum forces. String theory says that if you take all of the particles and forces and dimensions that the theory predicts, you can come up with ten to the five power different possible combinations among them. If you consider each of those combinations as a set of rules for a potential universe, including the combination that governs our own universe, then you have as many possible universes as ten to the five power. Our universe just so happens to be one with the combination of those dimensions and particles and forces that allow for life. That's the basis of what's called the anthropic principle. The kind of universe where life could evolved is the only type where we would find ourselves wondering about why things seem so finely too fine tuning may really not mean anything at all. By learning about the reality of our universe, physicists will answer questions like this, and when they do, they will be able to do amazing things like predict anything that could possibly happen with absolute accuracy, and perhaps future physicists will learn to construct new universes within their particle colliders grow them from seat. Exactly how we may someday be able to do this has already been roughly sketched out, and now the data must catch up to the theories. To some people physicists creating new universes where life might arise organically, it's actually a dreary sad idea. Any universe we might create in the lab would almost certainly have its own space time, and so it would be totally detached from our own universe, And so those physicists who created that universe would have no way to alleviate the profound suffering that life in that other universe might experience. To people who believe that the purpose of life is to reduce suffering, creating a universe like this would be a profoundly irresponsible act by a creator God with no power to interview. But there is also a tremendous amount of promise in the idea of lap grown universes. Perhaps we will be the life that populates them. Perhaps future humans will be able to grow new universes to move into when our universe begins to expire. Perhaps, unbeknownst to us, those physicists of the future will be carrying out the same kind of experiments that produced our universe, or perhaps they will be creating our universe. For phaps, that is how we will make our escape back to the beginning. Perhaps that's what we've always done. On the next episode of the End of the World with Josh Clark, the future is what's called a transgenerational global commons. We share it not just with everyone alive today, but everyone to come as well. And for the first time in human history, it is in the power of those of us alive to save it or destroy it permanently. And now, if you think about what the existential risk mitigation is, not all that is it the global public good existential risk mitigation, but it's also of transgenerational public good. But to take on the existential risks we face, we will have to overcome our own worst impulses.