0:01 what happens if you just keep cutting in half let's start with an apple and a really really sharp knife you take the knife in your hand and with a flourish you slice the Apple into two neat pieces the Apple halves become quarters then the quarters become e/s in front of you are smaller and smaller pieces of pulpy white Apple but by your 14th cut a regular rectangular pattern imers es and you realize the smooth Apple flesh is built out of an array of plant cells you keep on cutting chopping the cells into smaller and smaller pieces another eight Cuts reduces the cells into complex molecules of carbon hydrogen and oxygen and with a few more Cuts what was once
0:47 the apple is now 10 to the power of 27 individual atoms is this it can you cut no more but your knife is incredibly sharp and you begin to chop into the atom peeling away the cloud of electrons you reveal the seeming nothingness within almost nothingness for at the center sits the tiny Atomic nucleus 100 trillion times smaller than the Apple that you started with but again you are undaunted and again you continue chopping the nucleus splits into protons and neutrons the protons and neutrons into quarks and gluons and you find yourself in the Ethereal world of the subatomic a world governed by fuzzy probabilities the Apple now nothing but
1:32 an ethereal wave upon a sea of fields it feels like you have finally reach the limit the fundamental pieces of the universe though some you can keep going after more than a 100 Cuts pointlike quarks and electrons might be revealed to be waving strings bar a trillionth of a trillionth of a trillionth of a meter across by brating across extra Dimensions down here maybe even space and time are chunky fundamental blocks that can be cut no more or maybe any semblance of reality will melt away as we find that our universe is truly a simulated Cosmos churning away on some superdimensional
2:18 computer or that our three-dimensional existence is nothing but an illusion and everything we know and love is shown to be a hologram or even more strangely maybe it's just raw mathematics all the way down but which is true and how can we be sure to understand reality the true nature of reality and how humans over thousands of years of struggled to unravel it we are going to have to dissect the cosmos and ask some very difficult questions is the Apple real you can hold it smell it taste it you can see the greenness of its skin in the
3:04 sunlight surely the apple is real but what does it mean to be real just what is [Music] reality Isaac Newton used to bookmark the pages in his books in a very specific way he would turn the corner of the page down onto the phrase or even the word he wanted to remember of course it was easy for him to concentrate as he had no mobile phone determined to distract him or suck him into endless Doom scrolling and so our sponsor today is the perfect learning tool for our Modern Age if you care about building a life of learning imprint is the app for
3:51 you if you haven't used it before you probably haven't seen anything like it it provides bite-sized lessons that take only a few minutes and a beautifully Illustrated and animated creating a highly visual effective and Interactive Learning Experience their Library includes courses book summaries and quick read articles on topics like psychology philosophy physics productivity Science History and many more I personally have been enjoying Carlo rll's dive into the mindbending physics of time and another exciting option I've been looking through is thinking fast and slow by Daniel caraman which helped me understand my own cognitive biases and so now is a great time to to try everything imprint has to offer free for full 7 Days by scanning the QR code visiting imprint app.com
4:37 universe or clicking on the link in the description plus as fans of the entire history of the universe you'll get 20% off imprint premium subscription to our truly ancient ancestors reality must have been obvious from The Plains of Africa to those wandering the snowy wastes of Northern Europe reality was what you sensed with your eyes and ears touch and tongue reality was simply out there the snap of a twig in a forest might tell them that their next meal is at hand or warn them that they might be on the menu for a beast with bigger teeth and sharper claws sensing reality was a matter of life or
5:22 death perhaps therefore in their day-to-day struggles these truly distant ancestors had little time to wander little time to think deeply about the world that surrounded them but as the human mind developed and thoughts expanded the nature of reality surely changed as well we know humans began to bury their dead almost 100,000 years ago quite what they were thinking as they Bid Farewell to their loved ones we'll never know but perhaps they were thinking of a world beyond our reality an afterlife these ceremonies provide insight into human thought and that there was more to reality than meets the eye or ear or nose ideas around spirits and gods and
6:08 invisible yet powerful influences began to emerge along with questions of meaning and purpose and of course the gods also gave us the Apple providing Delicious Fruit for us to eat there was no need to question the reality of the Apple Beyond this the answer was simply beyond the ponderings of the human mind only found in the thoughts of the Gods but others began to wonder more deeply Plato was one of the greatest philosophers of the ancient world living in Athens in the 4th Century BC his real name was aristocles with Plato being just a nickname a nickname that meant Broad and apparently referred to his stocky build the material world bothered
6:55 Plato where to objects get their material properties be the greenness of the apple skin or the fact that dogs have four legs our world Plato contended was not the real world and to understand this we will have to explore his famous allegory of the [Music] cave in this cave a group of prisoners are kept chained staring at a wall the prisoners have always been there chained in the cave and have never been outside and experience the real world all the prisoners can see is the wall in the cave in front of them but on the wall they see Shadows these are formed by sunlight streaming into the cave
7:41 entrance as people go about their daily business at the mouth of the cave what are they to make of this external reality one that they can barely see how are they to understand the real world but we can go further what if they are not really seeing shadows of reality from Beyond the mouth of the cave What If instead some mischievous people have blocked off the cave entrance and are Illuminating the prisoner's wall with a bright fire with this light these people can now play mind games with the prisoners using shadow puppets to play out stories on the wall no longer are the prisoners simply seeing people wander by the cave entrance now they can see stories of monsters and battles castles and
8:27 Kings what are the prisoners to make of this new reality is it any less real than before to them this image on the wall is their reality there is nothing else and so these exciting new Tales are as real as the previous Shadow People Milling about to them the monsters and battles are truly real Plato then asks us to consider that we are like the prisoners and the reality we experience every moment of the day is a projection a projection of a place where true reality plays out with our imperfect World being a shimmering image of perfection to Plato our experiences are just Shadows of a true
9:12 reality considering what we know now this was oddly preent but for the story of reality this was just the beginning for to reveal the secrets of the universe to unveil the ultimate truth of the nature of the cosmos the answers did not lie in the hands of the gods or ancient philosophy instead we would have to delve deep into the fundamental makeup of matter time and space we would have to turn to the insights into reality provided by scientific exploration and when we did things quickly got very strange indeed philosophy will clip an angel's wings conquer all Mysteries by rule and line unweave a rainbow
10:00 in the first few months of 1821 the poet John Keats died in Rome he was young only 25 but his body was racked by the scourge of tuberculosis in his short time he was prodigious writing on the natural beauty of the world around us and like many before and after he was only truly recognized after his death Keats was born almost 70 years after the death of Isaac Newton it was the time of the Industrial Revolution a revolution driven by Newton's insights into the natural world the Scientific Revolution of Newton and his contemporaries had sought to peel back reality and reveal it as nothing more than a manifestation of physical law in action and finally it had been Newton who had realized that
10:46 the white light of the sun contained all the colors of the rainbow and that water droplets in the sky spread sunlight in a glorious display from red to Violet the seemingly mystical appearance of one of Nature's true wonders had Keat complained been destroyed by Newton reducing it to little more than a prism in Kat's words Newton had tried to unweave the rainbow Newton's Triumph might have been kei's lament but as Newton began to unweave the nature of light he kickstarted a long tradition of science peeling away the very nature of reality to expose it bones let's think again about our Apple
11:34 of course one of the defining characteristics of a ripe apple is its colorful skin but just where does this color reside apples are made of a complicated mix of water sugars and more complex structures so why do we see the Apple appear green to answer this question we must delve deeper into the meaning of color and The Story begins with the last man who knew [Music] everything Thomas Young was born in the tiny Somerset town of Milverton in 1773 precocious from the very start he learned French Greek Italian Latin Aramaic Persian and more and was instrumental in deciphering Egyptian hieroglyphics soon after the discovery of the Rosetta
12:21 Stone for some of you Young's name might already be familiar as it was Thomas Young Who undertook the first of what's known as the double slit experiments we will return to Young's Double slate experiment later in our story artists knew that mixing colored paints produced new colors and three colors red green and blue seemed to be particularly important young proposed that the ey contains three kinds of fibers fibers We Now call cone cells one kind is sensitive to Red another to green and another to Blue the amount that each kind of cell is stimulated is passed along the optic nerve into the brain brain where it is mixed like paint in the mind to give us the sensation of color things however get weird when we
13:06 look at the eyes of other animals our closest relatives apes and monkeys of the old world are similar to us sensitive to three color bands but most mammals only have two equivalent to our blue and green this must reduce their color palette would they see a banana as being yellow bees have three color receptors one sensitive to Blue another to to green and yet another to ultraviolet reptiles fish and birds can have four or more color receptors indeed the small but violent mantis shrimp has a total of 12 receptors spread across the rainbow these animals must see the world in an array of colors that we can't even begin to imagine and so what are we to make from this confusing array of animal
13:54 Visions for humans the yellow of the rainbow matches the stimulated signal from the skin of a banana but other creatures probably wouldn't agree to them maybe a strawberry or broccoli or human skin is the same color as a banana this tells us something deep about the nature of reality our sight is nothing but a shadow of reality created by our brains it is subjective not objective we live in a visual simulation of our own making built from stimulations being fed into our brains Newton told us about raindrops and sunlight but the colors of the rainbow only exist in our minds the sounds that we hear are similar the Illusions an interpretation in our minds
14:40 of vibrating eardrums due to waves of pressure in the air we live in a virtual reality of our own [Music] making so if what we perceive is not truly reality then what is well space and time can at least be trusted the apple is here and now that is one certainty or is it for in the revolution that was to follow Newton and Young no part of reality was safe time ticked by slower in the past than today and in 2023 astronomers measured
15:29 should by just how much their focus was quazars from 12 billion years ago black holes weighing billions of times the mass of the Sun swirling in the intense gravity of these black holes matter orbits at close to the speed of light this matter is heated to billions of degrees and glows intensely visible Across the Universe but in the turbulent Maelstrom before it vanishes into the hole matter crashes and grinds and the intense light brightens and Fades like a cosmic firework display hidden in this flickering astronomers found a subtle pattern a special regularity and they realized that they could use this quazar
16:14 tick to measure the passage of time when the universe was young these astronomers compared The Tick of a clock today to the ticks of these quazars finding that the farther away the quazar the slower and slower these quaz way our ticks became and when the universe was oneth of its present age relative to today time was ticking at 1 fth its current rate this result was spectacular but it was not unexpected for this Cosmic dilation was written into the mathematical laws that govern the universe in a theory developed more than a century before a theory that forever changed the reality of space and time
17:00 [Music] I think therefore I am it was the French philosopher Renee deart who uttered these famous words and this deep musing on the reality of being has reverberated throughout the centuries but Dart starred into more than just the meaning of being one night in 1619 deart shut himself away in a small room to avoid the cold as a mercenary fighting for the Dutch Protestant State he had studied engineering and Mathematics but this frigid night would be like no other The Story Goes that Dart was confined to his sick bed staring aimlessly around the room he spied a fly walking across the
17:47 ceiling before launching into flight darting about and settling on the wall as the fly buzzed about from seething to wall and Back Again a thought wandered across to cart's mind how could he describe the Journey of the fly he realized that he needed a reference point to Anchor the motion of the fly and while this point is arbitrary he must be consistent and not change it he also realized that talking about the distance from this point to the fly is simply not sufficient because as well as the distance you need the direction of the fly to fully describe its motion then a startling thought came to Dart a realization that would simplify the fly's motion for his point of
18:33 reference dard took the corner of the room where two walls met the ceiling from this point Dart imagined lines running along the joins defining axes that meet at the corner at right angles if you project the fly's location onto each of these axes to cart reasoned then you get numbers and it's these three numbers that you need to specify the location of the fly at any instant three numbers to uniquely Define a location in three-dimensional space three numbers that change continuously with the ticking of the [Music] clock the cart's coordinate system seems obvious to us today children are taught to use it when they encounter location
19:18 and motion in elementary science for professional scientists laying down a cartisian coordinate system is the start of finding Solutions and so the cart's name continues to reverberate throughout the centuries dying in 1650 Dart was unaware of a young boy growing up in the English Countryside this boy Isaac Newton would grow to use these Notions of time and three-dimensional space laying these down as the mathematical stage on which all motion takes place it was Isaac Newton who laid out the rules that we now call classical mechanics in Newton's Universe time is a true absolute a single clock that ticks Across the Universe a tick that everyone agrees on space was slightly more
20:05 complicated as tart's contemporary Galileo had discovered as each Observer has the freedom to define the origin of their own coordinate system Galileo thought more in terms of stories than in the mathematics of Dart or Newton and he laid out his Notions on motions in thinking about being on board a ship he realized that if the ship was in a harbor or sailing smoothly on a glassy sea then the experience below deck would be identical however if the wind picked up and the ship began to speed up or if it sailed into choppy Waters so the ship began to rock and roll then those below deck would feel this change in motion as
20:52 plates and Cutlery slide off tables and people become unsteady on their feet from this Galileo declared that there must be no absolute rest in the universe all motion he said must be relative and the laws of motion must be the same for observers in a state of unaccelerated motion the first theory of relativity had arrived these ideas are reflected in Newton's equations of classical mechanics every observer in uniform motion can use Newton's three laws to calculate the outcomes of EXP experiments it's easy to test this Yourself by dropping a ball on a train station platform and seeing it fall to the floor repeat this experiment on a train traveling at uniform constant
21:39 speed and again the ball will simply fall if however you drop the ball at the start or end of the train journey the train will be accelerating up to speed or slowing down as it approaches its destination and dropping the ball at these times will see the ball Veer towards the back or front of the train seemingly def ing Newton's Laws as no forces are pushing in these directions these fictitious forces only appear as your coordinate system is accelerating and they vanish as soon as you achieve uniform motion this picture of the background of reality existed for several centuries until a Scottish physicist James Clark Maxwell finally unraveled the mystery of light and with it the bizarre reality of
22:26 our universe [Music] Maxwell's impact on science was enormous by the mid 1800s Maxwell had mathematically United electricity and magnetism there had been experimental clues that these strange phenomena were related but in a handful of equations Maxwell showed that these two things were one and the same this was already an immense achievement one for which Maxwell would become scientifically famous but he looked deeper into his equations and realized that they implied something profound he realized that light itself must be an electromagnetic phenomenon oscillating and intertwined fields of electricity and magnetism his
23:12 equations also revealed the speed of light a blistering 300,000 km/s but curiously not what this speed is relative to by just whose coordinates was this speed determined it seemed that a notion of absolute rest would be needed to save physics some had proposed that there was an absolute background an ether in which light propagated throughout the Universe and had been creating experiments to test the idea this included experiments bouncing light rays off mirrors or sending a current through an electrical circuit and lighting a bulb the outcomes of these experiments would depend on the motion relative to The Ether and were built to demonstrate that the Universe
23:59 must possess an absolute state of rest however this would be a serious headache for Galileo's idea of relative motion why would electromagnetism know about this state of rest while the rest of physics didn't seem to care why would Galileo's relativity hold for everything except electromagnetism why would the physics of reality have to be so [Music] complicated in 1905 one physicist stated that it didn't have to be so messy that the Universe was not split into some Physics that obeyed Galileo and some Physics that didn't no electromagnetism had to respect relative motion also and so at the start of the 20th century
24:46 Albert Einstein's special theory of relativity was [Music] born at its core the special theory of relativity reflects the dream of the lazy physicist the dream of explaining as much as possible with as little as possible Einstein demanded that all observers irrespective of the relative motion can use Maxwell's equations to calculate the outcome of electromagnetic experiments but this comes with an uncomfortable consequence as all observers must measure an identical value for the speed of light and this was simply not possible possible with Newton's notion of space and time and so
25:33 space and time Einstein claimed are not rigid or absolute instead they must be flexible such that times and distances depended on who is observing them this sounds like lunacy indeed this is not the experience of our everyday lives but experiments close to the speed of light reveal this Distortion of space and time and it was in the 1960s that irrefutable evidence for the twisting of time was found the focus was on a subatomic particle known as a muon effectively a heavier version of the electron but unlike the electron which lives forever muons only last for 2 millionths of a second after this the muon disintegrates into electrons and
26:20 neutrinos physicists knew that high energy muons were made in the upper atmosphere created when particles from deep space smash into the gas molecules as they travel close to the speed of light the muons should have traveled half a kilometer before decaying but physicists detected muons arriving at the ground after traveling many tens of kilometers why were these muons lasting so much longer than their lifetime said they should the answer physicists realized lay in Einstein's special theory of relativity and in particular a quantity known as the lorence factor a factor that dictates the D ation of time to explore this we must understand the immediate consequence that sprang from the special theory of relativity the
27:07 speed of light is an absolute speed limit to the universe no matter how hard we try or how much energy we have available no object with mass could ever get up to the speed of light the Loren Factor depends on the relative velocity but as speeds get closer to that of light the lorence grows unbounded and so though for the muon its life is over in just 2 millionth of a second for the physicists here on Earth the mu's life appears much longer and it makes it to the ground of course there is a flip side to this story the other side of Einstein's strange relativistic coin the physicists see the long lived muon traveling tens of kilometers before decaying but if you could ask the muon it would say it had
27:53 only covered a few hundred meters in its short life space as well as time can be distorted and dilated when speeds get close to that of light and Einstein also realized that this speed limit had profound implications for information as this could also not be transmitted faster than light a classic example of this is that we don't see the Sun as it is now but as it was 8 minutes ago and the light we see from the Andromeda galaxy set off before humans walked the Earth through their telescopes astronomers see galaxies as they were billi millions of years in the past indeed the universe as it is now is completely hidden from us we only spy as it was in the past along what is known as our past like cone the
28:40 further an object is the younger it [Music] appears and other consequences from Einstein's view began to flow where time and space mean different things to different observers without the absoluteness of Newton's time there is no universally agreed now and the relative nature of time means that observers disagree on how much time has passed Einstein immediately realized that this doomed a cherished idea the idea of synchronicity this is the notion that two events at two different locations happen at exactly the same time we experience this every day it is part of
29:25 the Rhythm of Life where things happen at certain times but this is all an illusion and to understand this let's take a look at one of Einstein's thought experiments consider three people riding in a speeding train Carriage one person stands at the back of the carriage one at the front and one in the middle as the train trundles along at uniform speed these three people decide to do an experiment the person in the middle of the carriage has equipment that will release a pulse of light light that pulse of light will travel to the back and the front of the carriage at either end of the carriage each person has a mirror that reflects the pulse back towards the middle and at the instant the light is reflected the person at
30:10 either end raises their hands in the air of course in any practical train Carriage this experiment would be over in a moment and the sluggish reaction time of the people would be the limiting factor but this is the beauty of thought experiments we can ignore all these day-to-day limitations and just concentrate on the physics let's think about the situation on the train everything seems symmetrical from the light pulse heading out and Its Reflection to the pulse being received back in the middle of the carriage and the experiment coming to an end it seems reasonable to say that both hands were raised at the same time it was synchronous but let's now think about the view of an outside Observer not riding the train but just standing on
30:55 the platform and for fun let's make the Train move very fast close to the speed of light just what does this outside Observer see as the Train rars by and the experiment is experiment well this is where it gets a little odd our outside Observer sees the experiment begin and the pulses of light heading along the carriage but remember what Einstein's special relativity demands that all observers see light travel at exactly the same speed the speed of light what influence does this have on what our Observer sees as the train is moving the back of the carriage is reducing the distance that the light has to travel while the front of the
31:41 carriage is moving away increasing the distance to the reflecting mirror the light eventually bounces off each of the mirrors and makes its way back to the middle of the carriage with the distan is changing again eventually both pulses make it back to the middle at the same instant but when the outside Observer is interrogated on what they saw how would they describe the experiment they will say that they saw the pulses emitted at the same time and that they saw the pulses arrive back in the middle at the same time but they saw the reflections and hands being raised at different times synchronicity depends on who is doing the observing while Einstein was pleased with the special theory of relativity he
32:26 immediately spotted a problem and that problem was gravity Isaac Newton had given us his equations to describe gravity back in the 17th century and these worked well in explaining the rate at which an apple falls from a tree or the orbit of the moon Newton's equations however depended on the distance between masses in Newton's Universe where time is absolute we can talk about the separation at a precise now but in Einstein's Universe where now is not universally to find just which separation of the masses should we consider which now is now this lack of synchronicity threw out the notion of a unique separation and Einstein could find no way to shoehorn
33:13 Newton's gravity into his relativity So eventually he had no choice but to reject Newton's gravity in its entirety he had to go back to the drawing board and redefine Gravity from the ground up but where in his equations could gravity be included the answer was even more bizarre than what had come before both time and space were malleable gravity could be encoded in the bending and stretching of the fabric of the cosmos it took a decade of effort but in 1915 Einstein had cracked the mathematics it is this general theory of relativity that we used to describe the
33:58 action of gravity today no longer is gravity a force between two masses now it is the curvature of SpaceTime it is these mathematics that we use to describe the expanding universe and even rely on in our daily lives to help run GPS the conclusions of Einstein's relativity still hold across the cosmos there is no synchronicity no universally agreed now time and space can be immensely L warped and distorted and whether things exist at the same time is simply in the eye of the Observer and so now we can return to the remarkable quazar study from 2023 did time really run slower when the
34:46 universe was young well if you were there back in the infant Cosmos 1 second would feel like 1 second but as the universe expands the light that travels through it is stretched this malleable stretchy nature of SpaceTime leads to what we observe in the distant Cosmos being pulled thin across time and so it seems to us that the distant past ticked by at a slower pace and an even more extreme version of this concept is shown in the time dilation experienced around black holes SpaceTime is Warped to Impossible Extremes in the center of a black hole but it is also warped and stretched as you get closer to the Horizon and so
35:32 your experience of time slows down in comparison to distant observers and bizar these two ideas time dilation around black holes and time dilation of the distant past despite the vastly different contexts in which they arise are effectively the same thing and so from the earliest Decades of the 20th century our vision of time was changed forever in Einstein's revolutionary view of the universe the passage of time is utterly personal your clock be it mechanical like a watch or biological like the beat of your heart ticks and talks at a regular one second per second but other people's clocks can tick radically different relative to
36:18 yours if they are moving differently to you if they sit somewhere differently to you in a different gravitational field or if they are located in a different epoch of the life of the universe this bending of time is part of the cosmos the long lived muons smashing into the surface of the Earth a testament to this as are experiments where atomic clocks are taken for Journeys around the earth ticking their own ticks so they are desynchronized when they are reunited and we might even be able to use this relative nature of time to travel into the future all we would need to do is hang out in the intense gravitational field of a black hole a place where time relative to the rest of the universe effectively grinds to a
37:03 halt so whilst minutes or hours pass for you when you emerge years and decades will have passed [Music] outside pulling yourself away from the distant Universe you drag your attention back to the Apple you feel sure that the apple is here right now no more than a couple of meters away but you now have to accept that your now is precisely that the now that belongs to you another way that your reality is yours and yours alone this thought makes you Furrow your brow as the idea swirls in your mind when and where reality is seems to be a
37:50 slippery question but what it is could perhaps be simpler what is the world around you made of how would you dismantle the [Music] universe the atom split huge Force released so Scream the headlines of the Melbourne Argus in May 1932 Cambridge achievement success of British scientists the nature of reality had been smashed into pieces the headline was carried in a newspaper 20,000 kilm from the laboratory in Cambridge a testament to the Earth
38:36 shattering nature of the discovery a goal of ancient philosophers and seers had finally been achieved for the British scientists Ernest Walton and John coft were modernday Alchemists but instead of fire and brimstone their laboratory gleamed with metal and wires with electricity magnetism and a beam of particles they were able to transmute elements lithium was split into two new atoms atoms of helium their Discovery showing that the world of the subatomic was now in the physicist's grasp the question of just what matter is had been on the minds of philosophers for a long time some objects were clearly similar stones of various shapes
39:22 and sizes were hard while the solidness of stones contrasted with the squishiness of human flesh they seem quite different even fundamentally different at their core philosophers had wondered if the stuff of nature was infinitely divisible weather like our Apple you could continue to slice it and dice it into smaller and smaller pieces but ancient Greek and Indian thinkers had a new thought that things are composed of ultimate pieces tiny pieces we now know as atoms from the Greek fron cutable to the ancient philosophers these atoms were the fundamental pieces of reality however the notion that all things are made of atoms remained a philosophical musing for a few thousand years but by the 18th century scientific
40:08 evidence for the physical existence of atoms was emerging and not from the experimental Laboratories of physicists but from that of a [Music] botanist the botanist in question was Robert Brown born in Scotland in 1773 he had a distinguished career traveling the world in the ship the investigator to chart plant life many years later in 1827 he was still studying the world of plants but his Focus was Tiny grains of pollen this pollen was floating on the surface of water and brown examined it under a microscope but what brown saw mystified him instead of sitting restfully on the water he saw them dance and jiggle Brown
40:56 knew that Paul came from plants so perhaps the jiggling was due to life in action that the pollen grains were able to propel themselves through the liquid but other materials clearly dead material like chalk dust showed the same kind of dance this browni and motion had nothing to do with life many people pondered the question of the jiggling pollen as seen by brown but the answer would not be found for another seven decades until 1905 arguably the most famous year in of science Albert Einstein's annus mirabilis in this year of Miracles Einstein is generally remembered for one particular Discovery his special theory of relativity and all the weirdness of space and time that that conveys but it
41:43 is also the year he revolutionized quantum physics through the photoelectric effect and he finally explained the weird motion found by Robert Brown Einstein's Insight is as simple as it is brilliant he realized that the jiggling of the pollen was not the pollen propelling itself but being propelled by external forces forces delivered by the Collision of individual water molecules but how can this possibly be a pollen grain whil it's tiny is a billion billion billion times heavier than a water molecule how can the crash of a water molecule into pollen have any influence at all imagine you are at a truly massive Rock
42:30 concert with music blasting from the stage you were deep in the crowd a crowd of tens of thousands of people now and again the crowd surges to the left or right front or back and in these surges all you can do is go with the crowd intermittently the surges die away as you stand shoulder-to-shoulder with your fellow revelers but the crowd is restless you are jled from all sides a push from here and a push from there your body moves as you try to hold your space but you slowly start to jiggle about due to the Relentless pushes these pushes are not even sometimes more from the right sometimes the left sometimes front or back with you unable to predict from where the next push will come no matter what you do your entire body
43:15 moves a little this way and a little that way Einstein realized that brownie in motion was precisely this kind of drunkard's walk every second he said an uncountable number of water molecules collide with a grain the net result is that these fluctuations and collisions back and forth lead to the random jiggling and the pollen grain dances along to the molecular tune from his calculations Einstein was able to calculate the size of the collisions and their fluctuations confirming that water was comprised of an immense number of absolutely microscopic molecules and so Atomic hypothesis became atom reality and atoms appeared to be the building blocks of our world and yet just as their
44:02 existence was proven these indivisible atoms began to divide it was in 1896 that HRI Beckel and Marie cirri found that the world of the atom was unstable and that some elements could transmute into others spitting out other pieces as they did so and in 1897 JJ Thompson discovered the electron it was clear that something was living inside the atom that made up reality and the race to split the atom and reveal its contents was on for his Discovery Thompson was awarded a Nobel Prize in 1906 but it was his prote that was to truly reveal the structure of matter the father of nuclear physics Ernest
44:49 ruford in the first decade of the 20th century Rutherford set two young men to probe the structure of matter in a dark room at the University of Manchester they peered into Inky Blackness they were looking for tiny flashes that indicated a collision as tiny pieces hit a fluorescent screen and the results so far had been precisely as expected the two men were Hans Gyer and Ernest maren giger's name would be immortalized in the radiation detector named after him but that still lays several years into his future for now he patiently stared into the darkness logging each of the tiny flashes that he spied the experiments continued counting flash after flash until one day Rutherford suggested that they look for
45:35 flashes where none should be expected so Geer and masden dutifully modified their experiment and again stared into the darkness and it was then they changed our understanding of physical reality forever ruford was stunned saying it was the most incredible event of his life at 40 years old he was still quite Young but had already been awarded a Nobel Prize for his work but with this new experiment the atomic world would never be the same again but why what had they seen and what had it meant Thompson's discovery of the electron had provided new Clues to the structure of atoms the electron clearly carried some negative electric charge so
46:23 inside the atom must be a mix of positive and negative charges as as overall they are neutral the question was just how this charge was distributed Thompson had proposed his model for the nature of the atom something we now know as the plum pudding model confusingly a plum pudding doesn't contain any plums but it's actually a fruit cake with raisins and the electrons Thompson said would just like these raisins suspended in a positive mixture of cake it was precisely this model of the atom that Rutherford was testing in his experiment he created a beam of alpha particles charged helium nuclei emitted from a radioactive source and directed them to crash into a foil of gold and it was The Recoil of these collisions that Geer and
47:08 maren were looking for as they peered for flashes in the dark as the alpha particles impacted the gold foil many of them sailed right through missing the gold atoms entirely however now and again an alpha particle would crash down directly into an individual gold atom Rutherford surmised that the should feel the push and pull of the charges within the atom and their paths would be deflected out of the beam if Thompson was correct and the atom was a general mix of positive and negative charges then these deflections would be relatively modest flung only slightly from the beam and this is what Gyer and maren had spied as they sat in the darkness of their Manchester laboratory but following Rutherford's
47:53 suggestion they also found alpha particles scattered Ed far far from the beam Rutherford was astonished for an alpha particle to be so radically scattered was simply impossible in Thompson's vision of the atom ruford would go on to say it was quite the most incredible event that has ever happened to me in my life it was almost as incredible as if you fired a 15in shell at a piece of tissue paper and it came back and hit you but the question remained if Thompson's atom could not explain the scattering of alpha particles what could Rutherford concluded that instead of being spread out the positive charge must be tightly concentrated so that there is an immense electromagnetic repulsion between the atomic charge and
48:39 the alpha particle so immense in fact that the alpha particle can be flung in any direction and this led to a rather confounding picture of just what an atom is Rutherford knew that the electrons in the atom carried a negative charge this charge must be broadly spread over the volume of the atom spread so thinly that they barely influence the alpha particles the electrons however carried very little Mass this meant that the totality of the mass must sit in the positive charge at the nucleus of the atom but whilst massive the nucleus is very small tens of thousands of times smaller than the atom and so with this
49:24 the vast majority of the volume of an atom became nothing but empty space with Rutherford's insights the startling Pandora's box of nuclear physics was open Rutherford's atom fractures our view of reality of the Apparently solid nature of the world around you every chair every wall every tree every apple is made of atoms tied together into Myriad molecules that Define structure color and everything else but it seems that this is nothing more than an illusion apples are made of water vitamins and butal and hexal acetate the molecules responsible for their taste but each atom in each molecule is really a cloud of electrons surrounding a minuscule nucleus and the vast majority of each
50:10 atom is nothing but empty space so the apple is mostly empty space and its solid appearance but an illusion of course it's not only the Apple but everything that has the illusion of being solid everything including yourself this is disconcerting but maybe you can try and comfort yourself with this image of yourself in reality maybe it's okay that atoms are mostly nothing but empty space they're still made of something with a nucleus and orbiting electrons surely those pieces are real surely those pieces are really there but as they had with the molecule and atom before it physicists would quickly realize that the mysterious nucleus of
50:56 an atom was also far from fundamental on the 10th of August in 1915 a sniper found his Target his rifle trained on the enemy he steadied his breathing and began to apply gentle pressure to the trigger Birds scattered as the shot rang out the sniper's aim was true and the enemy crumpled to the ground the sniper moved on there were plenty more to hunt but little did he know that his bullet had snuffed out one of the greatest mines of the 20th century World War I cost 20 million lives both Soldier and civilian with many more wounded and injured the failed
51:41 gipo campaign seeking to weaken the Ottoman Empire cost 100,000 every life lost is a tragedy a missing loved one whose potential goes unrealized but this is particularly true of Henry GJ Mosley for before he joined up to be a soldier something he did out of Duty and against the wishes of his family Mosley was a scientist who was unraveling the inner workings of the atoms nucleus born in 1887 in Dorset England the son of an Oxford Professor Mosley was a stellar student studying at Oxford before joining Rutherford in Manchester in 1910 he had started to use x-rays to bombard different elements with the hope
52:28 of revealing the secrets of their atoms as he did this he had spied x-rays being emitted a different energies and guessed something deep within the atom was causing them there was also a pattern in heavier elements thought to contain heavier atoms higher energy X-rays were emitted in Holland the amateur physicist Antonius Johannes vanen Brook presented a bold idea he knew that electrons carrying the negative charge in side atoms came in discrete chunks each electron appeared to have the same mass and the same charge so what if the nucleus was the same built of separate but positive [Music] charges all atoms appear to be
53:14 electrically neutral so these positively charged chunks should exactly balance the negatively charged ones and the only difference between the elements would be the number of positive charges in the nucleus as this would set the number of orbiting electrons and dictate how the atom interacts with others the simplest element would have one of these charges the next two and so on and Mosley realized that this was the pattern he was seeing with his X-rays and with this one Insight he rearranged the periodic table based on what we now know as the atomic number still the form of the periodic table that we use today speaking in 1962 long after Mosley untimely death the giant of quantum mechanics Neils bore said you see
54:01 actually the Rutherford work was not taken seriously there was no mention of it in any place the great change came from Mosley and who knows what else Mosley would have contributed to science had he not been cut down by that sniper's bullet in 1915 things moved quickly as the Great War ground towards its eventual end it was again Rutherford always at the Forefront who was deep in the Discovery and through his investigations into radioactivity he finally uncovered the true nature of the atom hydrogen was the simplest element just one piece of positive charge joined by one electron whereas helium had two positive charges and two electrons then
54:48 lithium with three of each berium with four and so on and so on like the electron each of these positive charges were identical both in terms of the charge They Carried and the mass they were made of ruford named these positively charged massive particles protons and eventually in 1932 after being theorized for years the neutron was also identified in experiments the makeup of the atom was complete it had started off as a mess of complexity becoming simplified through the realization that the world is built from 92 natural elements but with the discovery of the proton neutron and electron things became simpler as still with atoms of all the elements and their Isotopes built of nothing but these
55:34 three key pieces of reality in the outer reaches of the atom roam the electrons negatively charged tiny particles that whiz around at close to the speed of light and at the very heart of the atom sits the nucleus positively charged and comprised of protons and neutrons it is the home to atomic mass but as Rutherford's new view of atoms took hold others realized it spelled Doom for physics as they knew it it contained a fatal flaw there is they said no way an electron can remain in its orbit Rutherford's version of the atom should not be able to exist at all the problem came from James Clark
56:22 Maxwell's equations of electromagnetism these demanded that an accelerating charge must radiate away its energy as electromagnetic waves and as an orbiting electron is in a constant state of acceleration it must constantly lose energy it should spiral into Oblivion in the nucleus of the atom there was nothing in the physical laws of Newton or Maxwell that seemed to prevent this nothing in the laws of reality as we understood them could make matter stable so physicists made a decision they decided to change the rules and in the process change the nature of reality
57:08 [Music] forever in 1943 the father of quantum mechanics Neil bore found himself in a predicament Germany had declared his family Jewish and his arrest was imminent so with the help of the Dutch resistance he fled to neutral Sweden but his trials and tribulations were not over for the British heard of his escape and decided they needed this Quantum Legend the second world war had been raging for four long years and the Allies had decided that a new weapon an atomic weapon must be developed to end the Carnage B's insights into the subatomic world would benefit them and stop the enemy from following the same path retrieved from Sweden and traveling in Disguise as James Baker bore
57:55 eventually made made his way to a secret town in New Mexico and there at Los Alamos he contributed to the Manhattan Project and the building of the atomic bomb shil he always claimed that he wasn't really needed amongst the bright young minds but Project Director Robert Oppenheimer disagreed the early days of quantum mechanics were a heroic time it was not the doing of any one man it involved the collaboration of schores of scientists from many different lands but from the first to the last the deeply creative subtle and critical spirit of Neil's bore guided restrained deepened and finally transmuted the Enterprise for three decades earlier in 1913 as the world had been on the precipice of Another World War bu's mind
58:43 had been focused not on how to unleash the power of the atom but the question of why atoms existed at all if Rutherford was right on the structure of the atom then why didn't the electron simply spiral into the just as the physical laws of Newton and Maxwell demanded revolution had been brewing for decades by the close of the 19th century physics had seemed pretty complete except for a few niggles yet those niggles came to dominate and rewrite physics as we know it and it all began with the question of why hot objects glow clearly to make an object glow you have
59:28 to supply it with energy this energy makes atoms vibrate vibrations that generate light the glow of a hot object we know that an iron poker in a fire glows with a beautiful cherry red and as we make it hotter this red gives way to white and blue but the question of why this particular choice of colors became the focus of A 42-year-old Max plank who combined the rules of established physics to understand how matter and light interacted but his calculations failed time and time again and as he reached a moment of absolute despair he decided to rewrite the physics rule book as many had done before him and would do after but never again with quite such far-reaching ramifications electromagnetic energy he
1:00:15 said came in distinct packets of light these discrete vibrations and light packets had to be quantized and suddenly Plank's Strange New Math itics explained the glow of a hot [Music] poker plank thought all he had done was perform a little mathematical Wizardry but by 1905 Einstein also said that light comes in discrete chunks Quant of energy explaining how electrons are rejected from metal when under a light source suddenly the quantized world was popping up everywhere the quantum Revolution was gathering Pace as the subatomic world was laid bare and it was Rutherford's insights that showed the atom itself would have to be quantized
1:01:02 but just what rules governed this quantized atom eluded him and these answers came from bore electrons said B were only allowed to exist in distinct orbits around the nucleus these orbits are set by the momentum of the electron and so each orbit has a specific energy electrons could move between orbits only if the ex exact energy difference is absorbed or emitted and there would be the smallest orbit that brought the electron no closer to the nucleus in demanding electrons could only exist in certain orbits with certain energies B had quantized and saved the atom from collapsing in on itself with only chunks of energy able to change the atomic
1:01:47 State this was a resounding success for B securing him the Nobel Prize in physics in 1922 but physicists still SC scratch their heads as to why the atom was quantized and this answer would come 2 years after B received his prize in Sweden from a radical proposition by a French Aristocrat and physicist named Louie de Bry he had been watching the quantum Revolution unfold and was perplexed by the notion that light which was a wave in classical electromagnetism sometimes behaved like a particle delivering its energy in a single punch in this Quantum world thought to Bry why should matter not be subject to this Duality so he declared that an electron which had been thought
1:02:33 of as a distinct particle also possessed wavelike properties in its existence just like light de Bry said electrons can be refracted and can interfere and it was Schrodinger who applied this to B's atom asking us to think of the wave of the electron as not at a precise point but spread over the entirety of the orbit and so balls quantized as atom finally made sense the electrons were behaving as waves and could only have certain wavelengths today the notion that Quantum objects can be particles and waves is common knowledge but in its time de bry's ideas shook the foundation of physics to its core and in 1929 de Bry found himself in Sweden receiving
1:03:20 his own Nobel Prize and so by the 1930s it seemed that reality was all sewn up the periodic table was built of just three particles protons neutrons and electrons bound together in different ways by the mathematical rules of electromagnetism and quantum mechanics but even this neat picture rapidly started to unravel in 1929 English physicist Paul durak had been focused on the equations of quantum mechanics his goal was to make Quantum consistent with the other great physics theory Einstein relativity his new equations worked but immediately dur was puzzled by what they told him for as well as describing the behavior of electrons something else was in the
1:04:06 mathematics the equations also described a positively charged electron a positron a particle that seemed to have no place in the orderly Atomic World perhaps people thought it was nothing more than a mathematical aity that has no place in reality but by 1932 it was unmistakably found in particle experiments but soon after the discovery of the positron a much stranger particle appeared in the collisions one that had even less of a place in the atomic world than the positron it looked like an electron with the same electric charge except for one key difference this new particle appeared to be 200 times as massive as the electron and unlike the electron this new particle the muon decayed in 2
1:04:54 millionths of a second and so the big question was why does the muon exist when it seems that it's not needed to build reality indeed particle physicist Isidor Rob equipped who ordered that as the muon made a mess of atomic neatness but its Discovery was the start of a Cascade with many strange and differing particles popping out of experiments and so into the 1960s chaos reigned in the world of the subatomic until the next level of reality was bear in what became known as the standard [Music] model it was realized that protons and neutrons and most other particles are
1:05:40 not truly fundamental but are made of even smaller pieces known as quarks we now know that there are six kinds of quarks grouped into three families the lowest Mass quarks are known as up and down then charm and strange most massive of all are top and bottom and the vast array of particles spat out in experiments are combinations of these quarks protons and neutrons are built from up and down quarks protons are two ups and a down while neutrons are two downs and an up three up quarks combined to form a Delta Plus+ particle whereas a D+ is a charm Quark combined with an anti-d down Quark as well as the quarks there are also the leptons the electron and the muon and the even more massive toon plus ghostly companions
1:06:28 known as neutrinos one for each kind of electron so the majority of reality we experience is a combination of electrons and up and down quarks there are a few other pieces to the standard model and we'll meet those soon but it's important to note that these fundamental pieces appear to have no size at all these truly fundamental pieces of reality are pointlike so in a way each of your protons and neutrons is effectively empty at the subatomic scale your atoms are even emptier than Rutherford found your brow farrows as you think again about the Apple knowing that it is mostly empty space was disturbing enough
1:07:14 but at least the electron and the atomic nucleus seemed solid in the quantum world this is simply not the case everything we thought was a particle is not Quantum matter shows wavelike properties spread out over space and not in any precise location or with precise properties your Apple is nothing more than a mix of these bizarre waves all combining to be the fruit you see you squint at the Apple as the question of quantum waves washes over your mind just what are these waves and just what is doing the waving is this what reality is just a sea of subatomic
1:08:00 [Music] waves imagine that you were in your kitchen mixing ingredients to bake a cake as you read through the recipe you see that you need a couple of eggs and so you head for the fridge in the fridge door the eggs are neatly arranged in lines with some holes filled and some holes empty you close the door and get back to your baking thinking little of the remaining eggs in your mind there are certainties when you open the fridge again the eggs will still be there occupying the same holes as before how could it be any other way but our modern understanding of reality suggests that the universe is
1:08:46 actually much stranger instead of eggs let's think of a collection of electrons similarly arranged in holes with the arrival of quantum mechanics in the early 20th century it was realized that electrons cannot be described by the rigid rules of the physics of Newton instead of exact positions and velocities electrons were described by probabilities we can only talk about the chance of finding an electron here or there and if we observe an electron in a particular hole it will have a probability of being in the other holes so next time you check on the electron it might have tunneled into a new new hole and all of the electrons might have switched [Music]
1:09:35 places and so why don't the eggs in your fridge similarly hop between the holes in your fridge door they two are governed by the rules of quantum mechanics and so by probabilities well in a sense they do for although the chance of an entire egg quantumly jumping between holes is extremely tiny it is not zero though very unlikely within the laws of physics everything is possible in the quantum world it is just a case of probability the quantum Revolution dominated the physics of the early 20th century great minds from around the globe turned their attention to the strange Realm of the subatomic but not
1:10:21 everyone was pleased with what this revolution had to say including perhaps the greatest scientist of them all Albert Einstein the problem started in 1926 in a paper by the physicist Max Bourne a year earlier anen Schrodinger published his ayous equation this allowed physicists to calculate the properties of De bry's matter waves but Schrodinger still didn't know just what these waves were Bourne however said that everything makes sense if you interpret the waves as waves of probability the amplitude of this wave function tells you the chances of an electron being here or there and as time Ticks by this wave function can wash back and forth as the probabilities for an
1:11:07 electron being in a particular location change this answered one of the questions that had been nagging physicists when considering Quantum waves because when they experimented on electrons they would see precise dings in their equipment they would detect individual electrons as distinct particles so how could they also exist as Quantum waves to Born the particles like electrons behave like waves as they travel from one place to another but when they interact with your detector the wave collapses and the electron is at a precise spot experimental evidence was quickly sought to see if this picture was correct and it didn't take long to arrive
1:11:53 [Music] the experimental setup was similar to Young's famous double slit experiment where light was shown through two slits and showed the unmistakable patterns of interference this demonstrated that light traveled as a wave as you need waves to construct interference And if quantum matter behaved like waves it should show interference too the idea was to fire a beam of electrons onto a target of nickel with a regular pattern of atoms if the electrons were little bullets we would expect them to randomly Ricochet off the target atoms however the experimenters found there were certain directions in which electrons preferred to recoil and other recoil paths they seemed to avoid and this was
1:12:40 the unmistakable pattern of interference places where waves added and strengthened and others where the waves canel each other out to help understand this imagine you are a sharpshooter at the Olympics through your nights you zero in on your target 100 m away you line up your crosshairs take a deep breath and hold it but as you think about your glory yet to come your mind starts wandering what if you were a sharpshooter in the quantum world in the quantum world the certainty of everyday physics melts away instead of exact locations and velocity your bullet is now governed by the rules of quantum probability and when you squeeze the trigger the bullet bullet emerges
1:13:25 from the barrel as a Quantum wave spreading out in all directions like the ripples of water on a pond this Quantum wave travels quite differently to the zipping path of the
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