the world is strange the whole universe is very strange but when you look at the details the rules of the game are very simple one of physics greatest Minds Richard Fineman once compared deciphering the laws of reality to watching the gods play chess except in this case you're only allowed to watch Snippets of the match and can often only view a tiny corner of the board from these scant Clues and snatched glimpses you have to work out the rules behind the movements of the pieces and instead of rugs Knights and porns you must attempt to decipher the laws governing fundamental particles such as electrons photons and quarks sometimes these investigations bring forth great Revelations at first you may notice that a bishop always stays on the same colored squares watch for long enough though and you'll discover that while true there is an even more fundamental rule at play Bishops can only move diagonally which in turn explains why they always stay on the same colored squares the history of understanding our world is littered with similar Revelations often two sets of rules are suddenly married together into one what looked complex instantly gets simpler two apparently separate forces revealed to be actually two sides of the same coin two particles just equal and opposite vibrations the Ying to each other's yang but the path to this point has been an arduous one every time physicists have thought they were getting close to understanding all the rules they have spotted some tiny hole in their theory that they can't explain it's the equivalent of one of the special moves in chess castling this is when the king moves more than one space and swaps order with the Rook castling simultaneously breaks three of the normal rules of Chess and yet can be a very powerful move a decisive move in any match as Fineman said it's the thing that doesn't fit that's most interesting it has to do with curiosity it has to do with people wondering what makes something do something what we are looking for is how everything works what makes everything work this long and winding road has delivered modern physicists to the precipice of a remarkable breakthrough when might not need an endless list of ever more complicated rules instead it is possible that all phenomena in the known universe from the tiniest subatomic particles to all the fundamental forces and so by extension even ourselves can be explained using just one rule that almost everything is simply vibrations in a vast web of quantum Fields but is this really the end of the game or are there still quirks in the rule book lurking just Out Of [Music] Reach thank you to better help for sponsoring this video everything we call real is made of things that cannot be regarded as real the world of theoretical physics is full of moments that pull the rug from under you and so is day-to-day life sometimes you just need someone to help you organize your thoughts betterhelp is the world's largest therapy service and it's 100% online with betterhelp you can tap into a network of over 30,000 licensed and experienced therapists who can help you with a wide range of issues whether existential questions like what is everything made of to more downto Earth problems to get started you just answer a few questions about your need needs and preferences that way better help can match you with the right therapist from their network with better help you get the same professionalism and quality you expect from in-office therapy but with a therapist who is custom picked for you with more scheduling flexibility and at a more affordable price so get 10% off your first month at betterhelp.com hot and I've also linked them Below in the description thanks to better help for supporting educational content on YouTube and then to discover if you try to get answers that they are related to each other that things that make the wind make the waves that the motion of water is like the motion of air is like the motion of sand the fact that things have common features it turns out to be more and more Universal what we are looking for is how everything works what makes everything work cities and continents whiz by as the Japanese Hitomi satellite hurtles around the earth at almost 30,000 kilm per hour it is racing so fast it sees 15 sunrises and sunsets each and every day with a total spend of 300 million 30 years to build it was conceived to look at some of the most violent events in the known universe yet within weeks of launch it would meet a violent end of its [Music] own a catastrophic system failure sends its spinning out of control the team behind the mission triy firing on board thrusters to slow it down but that only makes Hitomi spin faster it is now rotating so quickly that its solar panels Shear off and the satellite breaks apart into pieces the mission over before it is barely begun but why what brought down htoi the ensuing investigation discovered that the initial failure occurred isomi passed over the South Atlantic anomaly a dent in the Earth's magnetic field this exposed it to higher levels of radiation from space frying its delicate circuitry the Earth's magnetism usually acts like a giant bubble protecting us from the ravages of such radiation it begins deep in the bowels of the planet as the Earth's molon outer core spins surging through the crust and out into space it spreads its magnetic tendrils out to around 6 million kilm the South Atlantic anomaly is caused by a magnetic reversal in a small part of the outer core and satellites passing through the region are left vulnerable and so though it may pass by unseen in our daily lives the magnetism all around us is extremely [Music] powerful humans have been fascinated with the Earth's magnetic M for Millennia the first compasses were made 2,000 years ago during the Han Dynasty in China when naturally magnetized pieces of iron called load Stones were used for Land Navigation centuries earlier the ancient Greek philosopher thales of meitus thought load Stones had Souls because they attracted iron to them but it took far longer for scientists to explain magnetism and in doing so a fascinating New Concept crystallized the field in physics a field is a region in which each point has a physical quantity associated with it television weather forecasts are a good example because they show how the temperature varies across a given region of the Earth's surface those maps are temperature Fields they tell you the temperature you'd experience if you were placed in a particular part of the map similarly the Earth's magnetic field is a map illustrating the strength and direction of the magnetic force a particle would feel at various points around the planet the South Atlantic anomaly is a part of the map where the Earth's magnetic field is particularly weak the International Space Station has extra shielding to deal with the increased radiation that lets in and astronauts aren't allowed to Space Walk while passing through this region first used by English scientist Michael Faraday in 1846 he saw Fields as more than mere mathematical Maps he considered them physical objects that fill otherwise empty space and to illustrate this Faraday used this idea to help explain the perplexing behavior of ordinary bar magnets at some point every child becomes fascinated with the magic of magnets try and push two North Poles together and they resist you can feel them pushing apart from one another how can they do that without even touching what's going on in the space between them them farad's answer was that the magnets may not be touching but their magnetic fields are his explanation introduced the concept of field lines you may remember the classic School experiment of sprinkling iron filings around a bar magnet which Trace out the magnet's field lines looping out of the North Pole and back into the South Pole the magnetic field is strongest at these poles and so the field lines are packed more tightly together at least that's the 19th century when of thinking about it as we will see the truth is much stranger yet that was not the end of Faraday's genius his most famous discovery came when he found that changing a magnetic field can induce an electric current in a nearby circuit a decade earlier the Danish physicist Hans Christian stad had spotted the reverse that an electric current passing through a wire deflected a nearby compass needle away from magnetic north clearly a changing magnetic field could influence an electric field and vice versa why were the two Fields so connected the answer would come from Scottish physicist James Clark Maxwell in 1865 Maxwell describes Faraday and Ed's discoveries mathematically this work is so important that in 1999 leading physicists voted Maxwell the third greatest physicist of all time behind only Einstein and Newton Maxwell's equations should show that rather than being two separate Fields electric fields and magnetic fields are both components of a single electromagnetic field that's why changing one changes the other you're altering parts of the same thing Maxwell had combined two seemingly separate phenomena into one in the chess game of the Gods spotting that changing magnetic fields and electric Fields influence each other is the equivalent of realizing that the the Knight always alternates between white and black squares uniting them into the electromagnetic field is akin to discovering that's because the Knight always moves in an L shape you reached a deeper more comprehensive understanding of the rules and the Quest for similar unifications has kept physicists busy ever since this was just the tip of a very large scientific Iceberg for Maxwell had another trick up his [Music] sleeve imagine an electrically charged particle it generates an electric field around it just like a magnet creates a magnetic field the particle then starts moving up and down this changes its electric field which also then generates a changing magnetic field according to Maxwell's equations the constantly changing Fields produce ripples that move outwards through the electromagnetic field electromagnetic waves how frequently the particles move up and down dictates how long it takes for the Peaks and troughs in the electromagnetic waves to repeat from his equations Maxwell calculated the speed of these electromagnetic waves and the answer he found was remarkable they move at the speed of light surely not a coincidence Maxwell became convinced that light is itself is an electromagnetic wave indeed if true it would explain how sunlight reaches us despite the sun being 150 million kilometers away the electromagnetic field would fill the empty space between us and light could Rumble through it like an ocean wave but how could this be proved definitively the man with the answer was Heinrich Herz now so synonimous with electromagnetic waves that the unit for measuring how many times they repeat in a second is named after after [Music] him Herz first sets up a device capable of producing an electric spark then he readies a receiver 15 M away when the generator Sparks another spark soon follows in the receiver to prove that this is caused by an invisible wave traveling between the two devices herds puts a mirror between them he has to move the receiver in order to get it to spark again because the mirror reflects the wave onto A New Path he's even able to measure the speed of the wave which turns out to be the speed of light Herz has discovered radio waves Maxwell is Vindicated the rules of the game updated definitively light was an electromagnetic wave and yet something didn't quite fit light was only an electromagnetic wave sometimes remarkably the very same experiment that provided evidence for light as an electromagnetic wave would ultimately show it to be something else entirely a particle Herz noticed that the spark at the receiver was brighter when exposed to ultraviolet light later experiments by other scientists including Philip Von Leonard showed that electrons are expelled as a metal absorbs light which is what brightened Herz his spark brighter light has higher waves so they should have dislodged more electrons as they crash into the metal yet Von Leonard found that it was light waves that repeat more often those with a higher frequency and not intensity that liberated more electrons this became known as the photoelectric effect and would Herald perhaps the biggest revolution in the history of science an explanation would soon follow from none other than Albert Einstein despite being famous for his theories of Relativity it was this work on the photoelectric effect that would land him the Nobel Prize for Einstein argued that light isn't a continuous wave at all but a series of particles fired out like bullets particles that today we call photons how much energy each Photon has depends on the light's frequency and only photons with high frequencies have enough energy to dislodge an electron it's similar to a boxing match lots of continuous low energy punches do little one sizable knockout blow is all it takes this was a truly bizarre Discovery and one that would force physicists to concede that their entire chess game was hideously outdated almost without exception every rule would need to be Rewritten complete with startling Revelations about the true nature of our reality and even ourselves by the end of the thread that Faraday started pulling in 1846 we would find ourselves living in a totally different universe but to start with to begin unfolding the rules of this new game physicists would have to figure out this simple mystery why does light come in packets with set [Music] sizes [Music] we are trying to prove ourselves wrong as quickly as possible because only in that way can we find progress as night falls dobri ignites into a riot for the senses the smell of Japanese street food wafts through the air as throngs of people bustle noisily between the crowded or sakan Alleyways but it is the Kaleidoscope of color that hits you most everywhere you look near neon signs flood the streets with light advertising king crab octopus balls and revolving sushi restaurants and deep within these famous neon signs there's an equally frantic Hive of activity unfolding instead of people scurrying about tiny subatomic particles called electrons Dart this way and that without them the streets of doton Bor would be dark they are also the key to understanding photons let's Journey inside one of doton B's red neon signs which are filled with hydrogen gas to reach the individual atoms of hydrogen we have to zoom in an incredibly long way a hydrogen atom is almost unfathomably small around 83 million times narrower than one of your fingernails if you were to shrink the Earth by the same amount you could hold the planet in the palm of your hand hydrogen is the simplest atom in the universe made of just two particles a positively charged proton in the center with a negatively charged electron whizzing around it although far from A Perfect Analogy it's similar to the Hitomi satellite orbiting the Earth indeed this is how Danish physicist Neil's bore pictured the hydrogen atom in 1913 in what has become known as the bore model however B argued that the electron cannot inhabit just any orbit around the proton instead electron orbits are like the food served in the doore streets you can't buy a portion in any size you like you have to choose between set predetermined quantities such as small medium or large anything in between simply doesn't exist in the bore model electron orbits are similarly quantized meaning only certain restricted quantities or sizes are allowed these permitted orbits are called energy levels and they are the secret behind Doon B's cacophony of color if you pass an electric current through a gas then you give its electrons an energy boost which they use to jump up to a higher energy level when they fall back down again the energy they lose is spat out in the form of a photon the energy of the photon is equal to the size of the gap between the energy levels in turn this governs the color of the light we see red light has the least energy violet light the most if all orbits were possible then we'd only see white light as all the different colors from the Myriad transitions Blended together here that is not what we see if you take the light from glowing hydrogen gas and pass it through a device similar to a prism then you reveal hydrogen's Spectrum the visible part of this spectrum consists of just four colored lines painted on a sea of black these lines come from photons emitted when electrons drop down to the second energy level from the sixth fifth four fourth and third energy levels respectively the Blackness between the lines is a Barren Wasteland it's devoid of light because the electron transitions needed to illuminate it simply don't exist this pattern is the coing card of the quantum atom but of the four lines the red one on the far right known as H Alpha is significantly brighter than its neighbors it is drowns out the other three and so the streets of Doon borri are drenched in Red so far so good not simple but at least rational by the 1920s many of History's Greatest physicists from Max plank to Einstein to bore had worked on this model of the atom the result of following the implications of Einstein's photoelectric effect to their logical end but of course in fineman's Cosmic chess match there was always some tiny obscure move that blows a gaping hole in your theory one innocuous observation that makes you realize everything isn't quite as it seems and this particular crack was especially minuscule if you look carefully at the H Alpha line You'll see that it isn't one line at all but two a dublet these lines almost imperceptibly close together separated by distance 250,000 times finer than a strand of spider silk physicists call this fine structure and the bore model cannot explain it fine structure is itself the equivalent of a big neon sign flashing with a warning Theory incomplete once again physicists were forced to return to the drawing board and today the solution to the Fine structure riddle lies on the other side of the world in a place as popular with tourists as the street food stalls of Doon Buri Westminster Abbey with its imposing Towers Westminster Abbey is one of the jewels in London's Crown kings and queens have been coronated within its walls for almost a thousand years it's also the burial place of many a British icon from Dickens and Darwin to Kipling and Newton and on the floor of the Abbey close to the monument to Newton a plaque commemorates the life of arguably the greatest English physicist since Newton himself Paul Adrien Maurice durak engraved on the plaque is the equation that not only represents the crescendo of D's genius but one that also resolves the fine structure problem and explains why the H Alpha line is a dublet the secret is a murky and mysterious property of electrons called spin we know that when an electrically charged particle moves it produces a magnetic field however experiments show that electrons are actually producing two separate magnetic fields and so they must be moving in two different ways an electron orbits around the atom but it is also said to be spinning so in a way an electron is similar to the Earth which both spins on its axis and orbits around the Sun except not quite for in the case of electrons spin is just an analogy they would have to be spinning faster than the speed of light to account for their observed Behavior nonetheless physicists still use the word spin to refer to the source of the electron's second magnetic field and fine structure results from these two magnetic fields interacting with each other like electron orbits and Doon bore street food spin is also Quant ized only certain quantities are allowed the spin of the electron is 1/2 but this can be either positive or negative so an electron can exist in one of two spin States up where its spin is plus a half and down where its spin is minus a half a spin up electron creates a magnetic field that adds to the magnetic field generated by its orbital motion boosting the electron up to a slightly higher energy level the magnetic field created by a SP down electron works against the orbital magnetic field relegating the electron to a very slightly lower energy level and so the two closely spaced H Alpha lines in the hydrogen Spectrum are produced by electrons dropping down from these marginally different energy levels D's Brilliance was to bring together several breakthroughs in early 20th century physics in order to explain the weirdness of spin in 1926 inin schinger published his famous Schrodinger equation just as a light can act as both a particle and a wave so can electrons the Schrodinger equation describes the behavior of these electron waves dur also folded in Einstein's special theory of relativity which describes how objects behave when they move at high speeds the result when durra published his own equation in 1928 the one engraved on the plaque in Westminster Abbey it showed that spin becomes an inevitable property of the electron once you treat it as a relativistic Quantum wave the bore model that describes electrons as like orbiting planets is consigned to the growing scrap heap of theories physicists have been forced to discard atoms are actually made of waves and particles at the same time the fine structure crack had opened up and consumed the atom whole but the best scientific theories don't just explain something we already know they also predict something that we don't the dur equation Works whether or not the particles it's describing have positive or negative energy so dur predicted the existence of a particle identical to the electron but with the opposite electric charge a particle of antimatter and just four years after durak published his equation the positron was indeed found by Carl Anderson [Music] son compared to the bore model the durac equation was certainly a more comprehensive set of rules for how the game of subatomic chess works but by this point physicists had understandably become wary of closing the rule book and they were right not to for as they would soon discover there were yet two more minuscule moves in a strange corner of the board though were not covered by d's rules and in an odd historical coincidence both were announced at the very same conference in 1947 during the second world war many of the leading lights in physics were repurposed to develop militarily useful technology such as radar and atomic bombs The Shelter Island Conference held near Long Island in New York was a chance to refocus on compiling the ultimate rule book of the universe the wonderfully named polycarp K announced his measurements of a property of the electron called its magnetic dipole moment his answer disagreed with a prediction by direct suggesting that there was still something far deeper and more mysterious at play and so to explain this let's return to our bar magnet it has two poles North and South making it a dipole if you place the bar magnet inside another magnetic field then it will try to align with that field like a compass needle swinging to Point North the magnetic dipole moment is a measure of the strength of this interaction the spin of an electron generates a magnetic field and so it is like a tiny dipole magnet but the question is how strong is its magnetic dipole moment if you don't treat an electron as a Quantum particle and assume that it is a small sphere that's actually rotating you get the wrong answer the real value of the magnetic dipole moment measured by Kush is about twice as big this difference between the quantum and non-quantum answers is called the G Factor the dur equation correctly treats the electron as a Quantum object and it predicts that the G Factor should be exactly two however kush's measurements said otherwise the answer he gets is 2238 this seemingly trivial difference became known as the electron's anomalous magnetic dipole moment it was yet another neon sign Illuminating our ignorance an unexplained Gambit in the chess game of the Gods but that was not the biggest shock at Shelter Island the war had seen huge strides forward in microwave technology and in his post-war experiments Willis lamb had seen hydrogen atoms spitting out microwave photons photons that simply shouldn't exist exist according to the durac equation two of the energy levels within the hydrogen atom should coincide instead lamb realized that they diverge by just one part in a million when electrons make the transition between them they produce the microwave photons lamb saw this unexpected energy level split became known as the lamb shift lamb would later reflect that it was the smallest of measurements with the biggest of ramifications could ran Lamb's work would not only land them a share of the 1955 Nobel Prize it would press physicists into extending durx equation into what would become the most accurate and exquisitly tested theory in the history of physics it would unite all we knew about the electromagnetic field and the quantum atom together into a single Theory but with this realization we'd be forced to accept a truly bizarre new reality [Music] quantum mechanics describes nature as absurd from the point of view of Common Sense and yet it fully agrees with experiment so I hope you can accept nature as she is absurd for the physicist Andre gim it was just another Friday night in the lab for the Frog it must have felt like it had been transported into orbit it hovers in midair spinning and flipping like an astronaut doing Som assaults gim dedicates 10% of his time to these seemingly outlandish experiments along with the Frog G and his team would levitate plants fish and even a mouse using strong magnets his efforts would win him the IG Nobel Prize in 2000 a satiric alternative to the Nobel Prize aimed at recognizing on usual or trivial scientific achievements and yet despite the Whimsical nature of gim's experiments you have a lot more incommon with his levitating creatures than you may think it might seem like you are currently touching the chair you're sitting on or the floor you're standing on but very simply you aren't you are instead floating on a cloud of particles when you walk you are not in contact with the ground at all instead you were standing on a swarm of of subatomic specters blink and you'll miss them ghost particles that haunt the quantum world this is the counterintuitive reality of the Gods game of chess to quote physicist Frank wilch what you see isn't what you [Music] get the fact that we are all levitating like gim's frog is the only logical way to explain the seemingly tiny inconsistencies seen by Kush and lamb the smallest of effects with the profoundest of consequences it turned out that the dur equation failed to account for cushion lamb because although it treated the electron as a Quantum object it still described the electromagnetic field in the way that Faraday and Maxwell did back in the 19th century instead the electromagnetic field also needed to be quantized it had to be treated as a Quantum field with all the mind ending consequences that would entail and so along with other physicists in the Years following his breakthrough equation durak began to develop a very bizarre vision for our [Music] world imagine that the electromagnetic field is represented by a string pluck the string and you give it energy to vibrate except that if this is a truly Quantum field these vibrations can only come in set predetermined sizes if you don't give the field enough energy to reach the smallest possible vibration then nothing happens physicists have a name for the smallest possible vibration of an electromagnetic field a photon photons and electrons therefore aren't particles embedded in a field they are the field photons Are vibrations of the electromagnetic field and an electron is the smallest possible vibration of a separate electron field these fields are fundamental fill the universe and exist whether a vibration what we call a particle is there or not here's another way to picture it imagine that a field is made up of a grid of tiles each one connected to a spring initially the field is completely stationary the tiles are all level and there are no springs bouncing up and down yet if you pull up one of the tiles in effect injecting energy into a small part of the field you can set one of the Springs oscillating up and down this localized vibration of a field is what we see as a particle crucially though the spring has some resistance if you don't pull on the tile hard enough then it won't budge in other words there's a minimum amount of energy required to create a particle you can increase the size of the oscillation by injecting more energy but in the case of quantum Fields only vibrations of set predetermined sizes are allowed hence H why electrons need a certain amount of energy to jump to a higher orbital vibrations within Quantum Fields only come in multiples of the smallest possible vibration anything in between is forbidden as well as this vibrations in one Quantum field can be transferred to another when physicists say that an electron drops down an energy level like in the Doon bore lights what they really mean is that a localized vibration in the electron field vibrates less this lost energy is transferred to the electromagnetic field creating a localized vibration there that we call a photon picturing this process using particles is perhaps easier to wrap your head around but there aren't actually any particles involved at all it is all just vibrating Fields interacting with one another the idea of particles as mere vibrations is known as Quantum field Theory and it also explains the an antimatter first predicted by durac an electron is a vibration of the electron field but its antimatter partner the positron is a vibration of the same field in the opposite direction the equivalent of pulling the tile down instead of up that's why the two so-called particles have identical properties save for their opposite electric charges when an electron and a positron meet their oscillations cancel each other out and the electron field stops vibrating their energy is transferred to the electromagnetic field which vibrates to create two photons this is called Annihilation the reverse can also happen when a photon's energy is transferred to the electron field to create an electron positron pair unsurprisingly this process is called pair production it was durak who first came up with a name for this theory of how light and matter interact he called it quantum electrodynamics or QED but how do these Quantum Fields explain kush's anomalous measurement of the electron's magnetic dipole moment and the lamb shift and where did the ghostly particles you're levitating on fit in the answer would come from physicist Julian schinger born in New York in 1918 schinger fell in love with physics during a lecture by dur that he attended when he was just 14 years old by 16 he'd enrolled as an undergraduate at the City College of New York clearly a precocious Talent legendary physicist Hans beer said of a 17-year-old schinger his knowledge of quantum electrodynamics is certainly equal to my own and I could hardly understand how he could acquire that knowledge in less than 2 years if QED explains the interaction between light and electrons through Quantum Fields those fields must also be subject to all the rules of the counterintuitive Quantum world and that includes the Heisenberg uncertainty principle the Heisenberg uncertainty principle is a loan agreement with the universe it says that you can borrow energy from empty space as long as you pay it back again within a certain amount of time the more energy you borrow the quicker you have to pay it back this borrowed energy can pull up a tile and vibrate a Quantum field to create a particle but then that vibration disappears again once the energy debt is repaid physicists refer to these ghostly vibrations as virtual particles it means that an electron is never really alone the electromagnetic field around it is constantly vibrating with borrowed energy creating a swarm of virtual photons that flit in and out of existence sometimes the virtual photons exist for long enough that they undergo pair production to produce virtual electron positron pairs but they also soon disappear before they vanish these Poltergeist particles Buffet the real electron into a slightly different energy level inside the hydrogen atom which is exactly what Willis Lam had observed they also influenced the electron magnetic interactions explaining why kushi's measured G Factor was slightly higher than in the dur equation which doesn't treat the electromagnetic field as a Quantum field in the years since physicists have measured the magnetic dipole moment of the El to an unbelievable level of accuracy according to QED the electron G Factor should have a value of 2.0 23193 43552 in February 2023 physicists announc the most precise measurement of the electron G Factor ever made their Answer 2.23 1 9304 3612 correct to about 1 part in a trillion making QED the most accurately tested theory in the history of physics it's the same as measuring the distance to the Moon to within less than the width of a human hair without the presence of virtual particles the G Factor would be exactly two they may come and go but their ghostly influence leaves an imprint on the real world that is there for all to see it's as if a piece on the chessboard has moved without anyone ever actually touching it our rule book has to include these Phantom moves too the fleeting existence of virtual particles has profound implications for the way we explain the world around us starting with how magnets work out goes farad's 19th century idea of field lines and incomes the exchange of virtual photons imagine that you and a friend are each standing on a boat if you throw balls back and forth between you the boats will move apart in the same way two matching magnetic poles move apart by exchanging virtual photons if the poles are opposites then they attract each other also by exchanging virtual photons but this time in a way that's a bit like throwing boomerangs between the boats instead of balls in a similar fashion it's virtual photons that make up the cloud upon which you are currently levitating like G's frog electrons orbit so far out from the nucleus that atoms are mostly empty space you should fall straight through the chair or the floor as atoms pass through atoms unhindered that you don't it's only because the electrons in the floor or the chair and the electrons in you are constantly exchanging virtual photons pushing each other apart like two Magnetic North Poles without ever actually touching you are forever floating on the most ephemeral of quantum clouds physicists have juggled with the implications of virtual particles ever since Heisenberg introduced his uncertainty principle in 1927 within 2 years scher's PhD supervisor and later father of the atomic bomb Robert Oppenheimer realized they presented a big problem for the success of QED when he used an early version of the theory to add up the contribution of the multitudes of virtual particles swarming around in a electron it suggested that the energy in electron emits as it changes energy levels is infinite QED could seemingly not explain something as basic as the spectral lines of hydrogen so beautifully explained by both bore and duraq calculations of the mass and charge of the electron also gave Infinity as the answer Infinity isn't even a number but instead the notion or idea of endlessness when it crops up in physics it is another a big neon sign imploring physicists to try harder this Infinity problem meant that Q looked Dead on Arrival yet another false Dawn but this was not to be the end for the theory for it was to eventually be salvaged by schinger and others in the 1940s using an incredibly powerful theoretical [Music] technique the lamb shift and the electron anomalous magnetic dipole moment had shown physicists that the effect of virtual particles is finite and not infinite the influence they have is measurable theorists didn't have to fully understand why QED initially gave the wrong answer all they needed to do was tweak their equations in such a way that they produced the values measured by lamb and Kush altering a theory in this way to Vanquish The Unwanted infinities is a mathematical Conjuring act called renormalization and scientists use the technique to this day to blast through seemingly impenetrable problems and so these two tiny effects in a shadowy corner of the cosmic chessboard became doubly important not only did they show that D's initial set of rules was incomplete they also helped to improve the set of rules that replaced it the Infinities were over come and suddenly QED was a working Theory capable of predicting real outcomes with startling Precision the first true Quantum field Theory schinger would go on to share the 1965 Nobel Prize with Richard fean and Cino tomonaga the other Grand Masters who also figured out the route to renormalization but the Staggering success of QED set physicists wondering if the electrom magnetic force between magnets could be so exquisitely explained as nothing more than ripples in a Quantum field what about Nature's other forces how far could they go how much of reality could be explained as mere vibrations in fields because Atomic behavior is so unlike ordinary experience it's very difficult to get used to and it appears peculiar and mysterious to everyone both to the novice and the experienced physicist the trail of people marching out of the wooden huts and over the chilot pass resembles an army of ants the bootprints left by their frostbitten feet snake for miles around the mountains 100,000 eager explorers have descended on Canada as Yukon River and the surrounding Klondike region a frenzy sparked by the discovery of gold but most never even make it to the gold Fields forced to turn back empty-handed by the elements or Worse killed by infectious diseases Avalanches or assault today the Klondike is far more Serene than it was during the Gold Rush at the end of the 19th century but the precious metal is still mined here and in 2022 miners une Earth very different kind of treasure buried in the permafrost a perfectly preserved woolly mammoth scientists estimate that the mammoth lived around 30,000 years ago but how do they know it is the answer to that question that provides the key to the next set of quantum rules for ever since the mammoth died a subatomic clock has been silently ticking away inside it a Time piece based on atoms of carbon 14 the nucleus of a carbon 14 atom contains six protons and eight particles called neutrons occasionally one of the neutrons spontaneously shape shifts into a proton as it's the number of protons that distinguishes different chemical elements from one another it is no longer an atom of carbon it is now an atom of nitrogen with seven protons and seven neutrons this random process is called radioactive decay and the more carbon atoms that have changed to nitrogen the older the specimen must be but this type of radioactive decay is governed by an entirely different Force than the one that controls magnets and electrons a force that appears to be considerably more feeble hence its name the weak force and the story of how physicists came to truly understand the rules of the weak force and its various moves on the board began in the Bronx High School of C in New York City way back in 1950 that year the graduating class at Bronx High contained not one but two future Nobel Prize winners not only that they would win the same prize in the same year for contributions to the very same Theory despite working on it separately they were shelin glashow and Steven Weinberg both glashow and Weinberg ended up at Cornell University after weinberg's father drove them around to look at various colleges after graduating glasow moved to Harvard to complete a PhD under the watchful eye of Julian schinger having renormalized Quantum electrodynamics schinger set glashow thinking about whether the weak Force could also be explained using a Quantum field we've already seen how the electromagnetic force is carried by virtual photons that flit between the poles of a magnet and even between your feet and the floor physicists call such Force carrying particles bons but which Bon is responsible for fering the weak Force the answer lies partly in the decay of carbon 14 into nitrogen 14 used in carbon dating the weak Force turns an electrically neutral Neutron into a positively charged proton along with an electron and a particle called an electron anti neutrino this process is called beta minus decare but it can happen the other way around too during beta plus Decay a proton changes into a neutron plus a positron and an electron neutrino in other words the weak force is able to change a particle's electric charge a photon the boson of the electromagnetic force does not have this power when an electron absorbs a photon it stays negatively charged so the weak Force must have at least two bons one involved in changing neutral to positive and another in changing positive to neutral it was Weinberg who chose the letter W for weak giving us the w+ and W minus [Music] bons and so physicists including schinger and gasha attempted to explain these weak Force interactions using a Quantum field Theory just as they had done for the electromagnetic force these W bosons were reason to be the minimal possible vibrations of the W field just as the photon is for the electromagnetic field just like the photons flying between magnets the w+ and W minus bosons involved in the two forms of beta Decay are also virtual pisted particles that disrupt reality before quickly disappearing back into the quantum shadows in this way we date archaeological Treasures with the help of particles that aren't really there except turning the weak Force into a fully-fledged quantum field theory was proving more than a little tricky for one thing the mathematics predicted three bosons not two and so glasow suggests the existence of a new electrically neutral boson instead Z for the fact it has zero charge so the weak force is carried by three bosons W + W minus and Zed they are the product of two different Quantum Fields one for the two W's and one for the Zed progress is made but there is a bigger problem this Trio of bons has mass they must do because the distance over which the weak Force operates what physicists refer to as its range is Tiny just 100th of a trillionth of a millimeter this Behavior suggests that virtual bons responsible for carrying the weak Force disappear incredibly quickly before they can get very far the time it takes for half of them to disappear known as their halflife is just three 10 septian of a second there are more of those half lives in a single second than have been second since the Big Bang some 13.8 billion years ago and this is why it's called the weak Force it's not that it's inherently weak when it does ACT instead the weak Force rarely acts at all because the virtual bons that carry it disappear so quickly the reason that a very short lifetime means that weak bons have a significant amount of M mass is again the Heisenberg uncertainty principle the loan agreement with nature that is responsible for virtual particles in the first place remember you can borrow a little energy for a long time or a lot of energy for a little time the incredibly short lives of weak bosons suggest they must have borrowed a lot of energy according to Einstein's famous equation eal mc² high energy also means high mass and so the weak bosons are reach around 100 times heavier than a proton or 160,000 times heavier than an electron but this through a spanner in the works weak bosons having Mass meant that renormalization the fabulous trick that physicists use to Vanquish Infinities from Quantum electrodynamics only worked for massless bosons like photons the Infinities were still all to present if you wanted to treat the weak Force as a Quantum field and its bosons as its vibrations and so it was Glow's old school friend Steven Weinberg who helped figure out the way through the Quagmire with a remarkable thought yet another condensing of the rules what if the electromagnetic field and the weak field were once one and the same while physicists had been busy trying to write the quantum rule book of the God's chess game astronomers had realized that the Universe began as an incredibly small hot point known as the Big Bang together physicists and astronomers began to explore the possibility that there was originally one so-called Electro weak field which separated out into the electromagnetic and weak Fields as the universe expanded and cooled if this Electro weak field had massless bons before the separation then it could be treated as a Quantum field without being plagued by the infinity problem the issue then became how to go from one field with massless bons to two separate Fields only one of which has bons with mass and this is how Weinberg got it to [Music] work let's say the electro weak field had four massless bons we'll call them W1 W2 W3 and B another field also needs to have existed which we'll call the H field the H field is initially dormant but spontaneously activates bringing its own four bons into play they are called H+ H minus h0 and little H the activation of the H field breaks the underlying symmetry of the electro weak field and it separates out into the weak and electromagnetic fields the H bosons also have the power to give other bosons Mass the W1 and H+ bosons combine into the w+ and the W2 combines with the H minus into the W minus W3 and B merge to create two new massless bosons one of them combines with h0 to make the Zed boson and the other one never combines with an H boson and so it never gains Mass it is the massless photon by now there's a chance you may have guessed what all the h's stand for higs and therein lies the beauty of this Electro week Theory sometimes called Quantum flavor Dynamics or qfd not only does it explain why the weak bosons have mass and the photon does not it also makes a big prediction one of the four original H bosons little H should have survived this convoluted process unscathed and so began the search for perhaps the most loaded particle in physics history the higs Bon schoolmates glashow and Weinberg shared the 1979 Nobel Prize in physics alongside Pakistani physicist abta Salam for their work on this Electro week unification suddenly we didn't need one set of rules to explain the electromagnetic field and a separate set to explain the weak field the rules of the electro weak field sufficed in much the same way James Clark Maxwell had United the electric and magnetic fields into a single electromagnetic field in the first place two seemingly totally different rules blended into one underlying framework but this was not the end for while theoretical physicists had been mapping all of this out experimental physicists had continued to probe deeper and deeper inside the atom and in doing so had found a zoo of particles and a whole new layer to reality the protons and neutrons within atoms also turned out to be made of smaller particles governed by yet another fundamental Force could this also be explained with Quantum Fields was the very matter that made up atoms simply vibrations [Music] too you can't say a is made of b or vice versa all mass is interaction your heart is pounding in your chest as the deafening wind Roars past your face as you hurtle towards the ground a heavy dose of adrenaline cses through your veins then at the very last second the bungee cord snaps you back from the brink of Oblivion this White Knuckle ride is similar to the experience of subatomic particles called quarks they make up the protons and neutrons found in the heart parts of atoms except if they try to free themselves from these particles they are always wrenched back in independently proposed by murel man and George Z in 1964 protons and neutrons are made of two different types of these quarks up and down inside a proton you'll find two up quarks and one down Quark the up quarks each carry an electric charge of plus 2/3 and the down Quark an electric charge of minus A3 so the proton has an overall positive electric charge a neutron has only one upark the charge of which is canceled out to neutral by its two down quarks and so there is no such thing as the Proton or Neutron field instead there is only the upcar field and the down Quark field up and down quarks are the minimal possible vibrations of these Quantum Fields the objects we call protons and neutrons are actually two different Quantum Fields vibrating in tandem the very atoms that make up our reality are nothing but interconnected vibrating [Music] Fields however understanding protons and neutrons in terms of quarks did present physicists with some challenges firstly like electrical charges repel each other just as like magnetic poles do so why don't the two positively charged up quarks in the proton push apart or the negatively charged down quarks in the neutron physicists reasoned that there must be another attractive Force at play mightier than the electromagnetic force the strong force like the electromagnetic force the strong force is also carried by massless bosons this time called gluons because it's only by exchanging them that quarks stay glued together gluons are the minimal possible vibrations of the gluon field but of course as we have seen time and time again there was still one small issue that would bring this new Theory to Breaking Point for in 1964 the same year quarks were proposed physicists had discovered a truly baffling particle the Omega minus particle the Quark zoo is home to beasts more exotic than up and down quarks there are also flavors of Quark called strange charm top and bottom each one is the minimum possible vibration of its own Quantum field meaning there are six Quark fields in total the problem was that the Troublesome Omega minus particle was made up of three strange quarks and this seemed to break a sacran law of quantum physics known as the POI Exclusion Principle we've already seen that all electrons have a property called spin with value equal to a half likewise quarks also have spin equal to a half the PO exclusion principle states that it's impossible for two spin half particles to exist in exactly the same Quantum state but what about the Three Strange quarks in the Omega minus particle let's say one of them has a spin of plus one2 and a second has a spin of minus one2 what about the third it doesn't matter if its spin is positive or negative either way it will still be in exactly the same state as one of its neighbors in direct violation of the POI exclusion principle The Omega minus particle was another big neon sign another crack in a theory that slowly revealed a whole new layer of ideas it told physicists that quarks must be ruled by some extra property that distinguishes them instead something electrons don't have color color is the charge associated with the strong force just as electric charge is associated with the electromagnetic a quark can have one of three color charges called red blue and green quarks don't actually have different Hues though like spin color is just an analogy using colors to name the three strong force charges was the brainchild of physicist Wally Greenberg who took inspiration from someone we've met before James Clark Maxwell in the 1860s Maxwell demonstrated that combining red blue and green light creates white light in other words all color disappears when the three are mixed equally when one of each red blue and green color charge combine they create a particle with a neutral color charge protons neutrons and Omega minus particles don't behave like they have this strong force charge so they must be color neutral that means they are made of one red Quark one blue quark and one green Quark no two quarks are exactly the same and the PO Exclusion Principle is saved and the fact that physicists use colors to name strong force charges gives the quantum field theory of the strong force its name Quantum chromodynamics or qcd Quantum electrodynamics has one Bon the photon and Quantum flavor Dynamics added a trio of weak bosons the w+ W minus and Zed however qcd says that the strong force is carried by a total of eight bosons an octet of multicolored gluons here's [Music] why like all Force carrying particles the exchanged gluons that stick quarks together are virtual Children of the Heisenberg un certainty principle we've already seen how virtual photons can turn into virtual particle anti-particle pairs that nudge real electrons similarly a virtual glue on can turn into a virtual Quark anti- Quark pair if quarks carry red blue and green charges then anti- quarks carry anti- red anti-blue and anti-green charges so the strong charge on a glue on is a mixture of a color and an anti-color when a quk absorbs a gluon containing a particular color charge it changes to that color so a blue Quark absorbing a gluon containing red charge turns red conversely when a quark emits a gluon containing an anti- color it changes to that color so a green Quark spitting out a gluon containing anti-blue charge turns blue this makes it impossible for a glue on to be made of a color and its own anti-color let's say a red Quark could emit blue anti-blue gluons this would both turn itself blue and turn the green Quark blue when it absorbs them you'd have two blue quarks inside the same particle there would no longer be one of each color to mix together to be color neutral so the Proton or Neutron would exhibit some overall color charge which they never do there are six ways to pair off three colors so that you never get matching colors in the same pair that's six gluons but what about the other two the quantum World being the weird and counterintuitive realm that it is there are actually two complicated ways for each Quark or antiquark to be a mix of colors while still leading to a neutral color charge this makes protons and neutrons like miniature universes Relentless hives of activity constantly shifting kaleidoscopes of color charges with a rainbow of virtual gluons quarks and antiquarks flitting here and there these virtual particles are so abundant that they make up 99% of the mass of a proton or neut neon the real quarks they are buzzing between contribute just 1% the very particles that make up every atom in your body are mostly made of things that aren't really [Music] there you can think of the constant back and forth of gluons between quarks as like a bungee cord between them physicists call it a qcd string try and pull a quark out of a proton and the bungee cord tenses and wrenches the Quark back in like our bungee jumper earlier it is possible to put in enough energy to snap the bungee cord completely yet this still doesn't set the Quark free instead the energy is converted into a quark antiquark pair called a Mison the Mison escapes and Carries away the energy but the Quark remains trapped collisions within particle accelerators are so energetic that the bungee cord is broken multiple times spitting out an abundance of me on they form Jets and it's these jets that particle physicists pour over for hints about what has happened only then the signs of color emerge as it's transferred from particle to particle yet these virtual meons have an even more important role to play in most Atomic nuclei there are multiple protons each with a positive electric charge like all electrically charged particles they're exchanging virtual photons which acts to p push them apart yet this is trumped by the virtual meons they are also exchanging which keeps them glued together physicists call this the strong nuclear force to distinguish it from the strong force that binds quarks they can also stick a proton and a neutron together every element in the periodic table heavier than hydrogen would be impossible without these virtual meons no stars no planets no life so not only are the particles You're Made Of mostly comprised of things that don't really exist those things are also held together by things that don't really exist either the more we figure out the rules of quantum chess The Stranger and stranger they [Music] become in 2004 David gra David pollitzer and Frank wilch shared the Nobel Prize in physics for their work on quantum chromodynamics they showed that the strong force and all its Myriad color interactions can be described using a renormalizable Quantum field Theory just as the electromagnetic and weak forces can that quarks gluons and misons are all just ghostly vibrations in Quantum Fields this means that currently everything in the atomic world can be explained using just two theories the electro weak Theory which includes quantum flavor Dynamics and Quantum electrodynamics within it and Quantum chromodynamics together they make up the standard model of particle physics the standard model describes a total of 17 vibrating overlapping Quantum Fields occupying every part of space there are four Fields associated with the force carrying bons the photon the W bosons The Zed boson and the gluon then six quark Fields one for each flavor there are also six Fields known as lepton fields leptons are particles not affected by the strong force that includes the electron field and two Fields associated with particles called the muon and the TOA plus a trio fields for the three different kinds of neutrino that's a total of 16 but what about the 17th field that is the much lorded higs field vibrations of which we know as the higs Bon that Bon was discovered in the summer of 2012 at cern's Large Hadron cider a cavernous cathedral built to prize answers from the standard model the discovery of the higs was a ringing endorsement of the standard model as the most comprehensive rule book for the gods chess game ever compiled it successfully explains how all subatomic particles and three of the fundamental forces can be described as mere vibrations of across its 17 different Quantum Fields waves and particles mass and energy light air Earth and the matter that makes up me and you almost everything could be reduced to vibrations in vast Universe spanning interacting Quantum Fields almost because for all of the standard model successes there is still one thing left one rule that just doesn't fit gravity if a lore does not work even in one place where it ought to it is just wrong clad in gleaming white space suits a team of astronauts check effects the last of the rivets and bolts an armada of robotic spacecraft sets to work cooling the magnets to a temperature lower than even empty space itself after centuries of toil the much anticipated machine is finally ready to call it vast would be an understatement it encircles the sun like the path of a planet orbiting far beyond any of the actual planets of the solar system its total length stretching to some 30 7 billion kilm and physicists are about to send subatomic particles in opposite directions around this super ring at close to the speed of light even though the particles are traveling at almost 300,000 kilomet per second physicists won't see the first collisions for a day and a half even then they'll need the particles to make millions of laps before they have enough data to piece together what's going on they will need to be patient it won't be for Generations s until they finally see the results the particles have to stream past the robots mining the space rocks in the asteroid belt for the materials required to make machines like this one by the Towering cities of New New York and New New Del on the dusty Martian surface and Beyond the sprawling solar Farms on Mercury that are powering Humanity's growing presence across the solar system this Mega machine is the ultimate microscope allowing physicists to zoom in and see reality at the smallest scales with its incredibly High energies this Ultra Hadron Collider is probing the so-called plank length which is just 62 nonilon of a millimeter across there are around a billion times more plank lengths in a single millimeter than there are stars in the entire observable [Music] universe it is only by exploring the universe in such minute detail that physicists can hunt for proof of what has always eluded them a theory capable of explaining every phenomenon in the known universe from the tiniest subatomic particle to the most gargantuan Galaxy a theory that proves once and for all that everything even gravity can be explained as ripples within Quantum Fields a theory of quantum gravity such an experiment is clearly a long way off but it represents the dream scenario for many physicists just as the electromagnetic and weak forces were once united into the electro weak Force physicists suspect the electro weak force was once Tangled Up with the strong force into a single Quantum field the fact that both have already been successfully described using Quantum field theories shows that they are highly compatible they look to be like two pieces of a locket naturally fitting together to make a hole the marriage of the two is known as Grand unified theory and it is an inherently testable idea for one thing physicists suspect it could lead to proton decay where the proton breaks down into lighter particles and so searches are already underway for proof of this process evidence that in turn the gravitational field was once spliced together with the grand unified field into a single quantum field is what our solar system sized accelerator was looking for just as the other three forces have Force carrying bons our future physicists r on the hunt for the graviton the minimum possible vibration of the quantized gravitational field yet despite this being a superficially logical extension such a notion is fundamentally incompatible with the way physicists currently understand gravity Alber theory of gravity is Albert Einstein's general theory of relativity it says that the universe is made of a fabric called SpaceTime if as Shakespeare wrote all the worlds a stage then SpaceTime is the stage and Quantum Fields merely players upon it the 17 Quantum fields of the standard model vibrate in space and over time SpaceTime is space and time time according to general relativity mass or energy embedded in SpaceTime creates a Depression known as a gravity well if a second object gets trapped in this gravity well then it will look like the first object is preventing it from escaping by pulling on it Isaac Newton thought that this was the attractive force of gravity but gravity isn't really a force at all it's just the effect of the curved SpaceTime inside a gravity well by describing it in this way general relativity treats gravity very differently to the way Quantum field theories explain the other three fundamental forces through the exchange of virtual bon in general relativity there's no bungee cord of virtual gravitons traveling between the Sun and the Earth and trying to explain gravity through the exchange of virtual gravitons instead is immensely Troublesome for one thing there's a problem when physicists calculate the chances of a particle emitting or absorbing a graviton the answer they get is significantly higher than one in probability the likelihood of events is scored on a scale from impossible at zero to certain but one a probability of more than one is saying that an event is somehow more certain than certain said another way there's more than 100% chance of it happening this is clearly nonsense and yet another red neon warning sign but there's an even bigger issue let's say the sun in the Earth really are exchanging gravitons those gravitons have energy so they would warp SpaceTime which would lead to more gravitons they too would warp SpaceTime leading to yet more gravitons very quickly this spirals out of control and races towards Infinity resulting in the equations blowing up and losing their predictive Powers if this sounds familiar you're not imagining it this is exactly the same problem that plagued early versions of quantum electrodynamics Robert Oppenheimer added up the effect of all the virtual particles swarming around the electron and he got Infinity as the answer blushes were only spared because the lamb shift and kushy's unexpected measurement of the electron's magnetic dipole moment showed physicists how to fudge their equations to produce the right answer through renormalization but physicists don't yet know how to renormalize quantum gravity and Vanquish the Infinities maybe another tiny Gambit will one day blast a whole in either general relativity or the standard Model A final move in the centuries old game of divine chess that physicists have yet to observe one that would help them to complete the rule book once and for all perhaps it will take a solar system sized accelerator to find it but in the meantime physicists have tried other ways to break the impass and the most famous attempt is string theory String Theory says that the particles described as fundamental in the standard model such as quarks and electrons aren't fundamental at all but are instead made of tiny vibrating strings just as you can play different strings on different musical instruments to produce different nodes so the universe creates the orchestral Masterpiece of the standard model by conducting its own string section open strings would have the properties of photons and gluons but a closed string could have all the expected properties of a graviton except there are a number of Fairly sizable catches to get rid of the problem of the probabilities adding up to more than one string theory has to invoke the influence of new particles that no one has ever seen to Vanquish the Infinities you also have to assume that SpaceTime has at least nine spatial Dimensions perhaps more as we only see four dimensions three of space and one of time the others must be curled up really small and out of site normally fineman's chess game gets simpler as successive unifications draw the rules together String Theory however seems to make it inherently more complicated with the need for a slew of new playing pieces what makes it even more complex is that there are countless versions of string theory and string theorists are sure which set of rules to use to make testable predictions to see if it's correct so what other options are there when pressed many physicists will concede that general relativity seems more likely to crack first we've seen many times how the discovery of some new Gambit forced physicists to throw away an existing non-quantum theory in favor of a new Quantum one perhaps we haven't seen the thing that breaks general relativity yet because we haven't probed small enough regions of SpaceTime and this idea is far from new one man was thinking about it as far back as the 1930s born in what is now Ukraine in 1906 matf Bronstein's work span an impressive gamut of subjects from semiconductors to Quantum electrodynamics and cosmology but it is his 1935 paper on the problem of quantum gravity for which he is most remembered let's say we want to measure a really small region of SpaceTime bronstein imagined placing a particle there to help us make the measurement it's here that the heis ber uncertainty principle re-enters our story we've already encountered the version relating energy borrowed for a certain amount of time but bronstein considered another version involving the position of a particle this version says that as you explore smaller and smaller distances you need a particle with a higher and higher energy to do so but Einstein's eal mc² tells us that energy means Mass eventually there comes a point when the distance you're probing becomes so small that the particle you need creates a gravity well so deep that nothing can escape and physicists already have a name for an inescapable gravity well a black hole your test particle has created its own black hole and since you can't see inside a black hole you can no longer measure the particle in other words there's a minimum distance below which it is not possible to measure anything just like there's a minimum vibration of a Quantum field you've zoomed in and found that SpaceTime doesn't look the same at the smallest scales after all if true SpaceTime would not be the smooth and continuous fabric that general relativity describes instead it would come in multiples of the smallest possible size bronstein had hit upon another way that SpaceTime could be quantized however the bright flame of Bronstein's genius was soon to be extinguished just 3 years after the publication of his work he was executed in a Leningrad prison as part of Joseph Stalin's Great Purge his wife Lydia was told he'd been sentenced to 10 years of hard labor he was just 31 years old but where bronstein began others would eventually follow today his work has morphed into the theory of loop quantum gravity according to this Theory SpaceTime is like a piece of of clothing from a distance it looks like a smooth fabric but Zoom down far enough and you'll see that it's really made of a network of individual stitches these are the loops in Loop quantum gravity the threads with which the quantum gravitational field is woven each Loop is unimaginably Tiny there would be more Loops in a cubic centimeter of space than there are cubic centim of space in the entire observable universe somewhere in the region of 10 followed by 99 zeros each Loop is a Quantum of the gravitational field so Loop quantum gravity does away with the need for gravitons and all the problems that come with them however so far like string theory there is no experimental evidence that Loop quantum gravity is the right approach [Music] either and so perhaps this Quest will be passed down to distant Generations who will build particle accelerators the size of the solar system to peer down into the depths of reality maybe then Loop quantum gravity or some similar Theory will relegate SpaceTime from its role as the stage on which all Quantum Fields tread the boards to just another quantum field then there would be no stage at all our entire reality would be created through Quantum field stacked upon Quantum field a universe made of nothing more than ethereal ripples you've been watching the entire history of the universe don't forget to like And subscribe and leave us a comment to tell us what you think thanks for watching and we'll see you next time
