The Concept of Mass - with Jim Baggott

Now this is called a

mass

, but I'm not taking confession well if you really insist and make me beg, maybe later we can do something like that with a pint of beer in the pub. I know it doesn't always seem like it. but believe me, an author really needs a reason to sit down and write a book, so my reason for wanting to write this particular book was to try to convey something, some sense of what has been an understanding of contemporary physics for quite some time. of years, but I actually felt that it was not so wonderfully well understood or commonly understood and that is the way that modern physics conceives of the nature of matter and in particular the property of

mass

, so what I want to try and to do is to give you a sense of the journey that I took researching and then writing this book to give you a sense, perhaps also of the sense of wonder or amazement of where contemporary science feels we have landed and that I am going to give as I settle down.

I hope it's not too difficult a mission, so here's my mission, Jim, if I decide to accept it, here's an ice bucket and I'll ask myself some really, hopefully, pretty simple questions about these things. I want to know what it is made of and I want to try to answer the question: where would you look for its mass so that we know that ice is not what you put in your gin and tonic or increasingly the cosmopolitan is among you in your glass of Sauvignon Blanc as Do Italians do it? We know it's made of water and we're going to start the story with the ancient Greeks because much of our common understanding of the nature of the material substance actually comes from a handful of Greek philosophers dating back about 450 years before Year Zero. , before the Common Era. names like Leucippus, if he really existed, Democritus, then about a hundred years later Epicurus and much of Epicurus' work was translated into a great poem by the Roman poet and philosopher Lucretius and a great place to begin with because Epicurus once said that nothing arises. of what does not exist, that's philosophers for you, I can guarantee you that cryptic crossword puzzles were ace in ancient Greek times, we are talking of course about the famous Greek elements earth, air, fire and water, that's good because we know that ice is made of water and we are interested in exploring a little more about what it is, what that water is made of and we have the feeling that nothing comes from things that do not exist.

A great start, what Epicurious is really saying is that it is our common observation. that nothing magically appears out of nowhere, things just don't appear and there is a corollary to that, if it is common experience that things don't magically appear, it is also our common experience that things don't magically disappear, take that to its logical conclusion . and you end up in a situation where you have to accept that nature resolves everything into its constituent atoms and nothing, no substance can be completely resolved into nothing, it is a simple logical consequence, if nothing can arise from nothing and nothing can be resolved into nothing , then by definition, when I have something, it must be resolved into some indivisible, individual, indestructible pieces, what the Greeks called atoms.

Even better, we know that the ancient Greeks speculated that if you accept that a substance like water consists of atoms, then by definition the atoms must move into something. What the Greeks called empty space is how we think of it today and there had to be a reason for that movement, so the Greeks had no real difficulty in attributing properties to these atoms, as you can see in the little diagram they gave them. they gave. Different shapes, some had spikes and hooks that stuck together, giving them certain characteristic properties that we can actually see manifested in our experience with different substances, but if they were perpetually in motion, then the argument was that they must have something called hold, you know. .

They fall through a vacuum much like heavy raindrops will fall from the sky on a warm Sunday afternoon in June, ok, even more so, seawater is fluid, ok, it must consist of round atoms, so here we get quite a few answers to our initial questions: what is it? It is made of well, ice is made of water, water is made of round and hard atoms that are indestructible and indivisible and those atoms, in turn, must have the property of weight, okay, good start, everyone happy, everyone happy, thank you, okay, then we have to wait. Oh, quite.

For a long time I have not wanted to give you the impression that nothing happened in the thirteen or fourteen hundred years between the ancient Greek philosophers and the times perhaps a little before Isaac Newton, the times of Galileo Bacon, Robert Boyle and others. . contemporary of Newton, but I thought I'd pull this quote from an online philosophy encyclopedia called the Stanford Online Encyclopedia of Philosophy and when I read it it really struck a chord, here's a recipe for producing medieval philosophy and everything that happened. in the thirteen hundred years between the Greeks and Newton combines classical pagan philosophy, mainly Greek, but also in its Roman versions, with the new Christian religion seasoned with a variety of flavors of the Jewish and Islamic intellectual heritage that stirs and cooks at slow burn for 1300 years or more until it was done, there was a lot going on, but most of the intellectuals, most of the minds of the thinkers of this period were devoted to trying to reconcile the pagan philosophical texts of the Greeks with the effective demands of the Catholic Church and other Orthodox and eventually, things began to free themselves, the first universities, of course, were created out of monasteries for all intents and purposes, so that kind of sense of monastic scholarship translated into scholarship academically and little by little, over a long period of time, it became possible to start speculating.

Along lines that were not so long and no longer theological, one could begin to speculate about the nature of the natural world that did not necessarily always have to reference some kind of religious orthodoxy, so, to be fair, although We tend to consider Newton Newton was one of the first among a generation of scientists, but in reality Newton was a mechanical philosopher. His famous book was published in 1687. Its tragic English title is The Mathematical Principles of Natural Philosophy, so these people understood that they were doing natural philosophy, but of a particular mechanical kind, it was the mechanical investigation of nature. .

Nutan, of course, had a lot to say about things like motion and gravitation, which we'll talk about in a bit, but these philosophers, these mechanical philosophers, also understood that substance was ultimately composed of hard atoms. indivisible, but his

concept

of mechanical atoms was actually not much more sophisticated than the

concept

ions that the ancient Greeks had proposed hundreds of thousands of years earlier. Well, Newton Oh, he went further. Newton speculated that not only were these little hard billiard balls of substance moving in a vacuum that they could actually also have forces acting on them, something the Greeks never latched onto as far as they were concerned, all motion was due to weight. of atoms, the idea that different types of forces could exist between atoms was new but highly speculative.

Newton had no experimental grounds to make that kind of claim. The other thing we would look for in Newton is a really good understanding of the things that manifest in our visual world of experience that have to do with the motion of objects, things with mass, things with acceleration as a result of the action of a force of some kind, so at least here, if we can't get more information about the nature of the atoms themselves, we can at least get some ideas about the nature of atoms. nature of this thing we call mass or weight that are not differentiated in this talk and in fact there is a definition of mass in the mathematical principles of Newton's natural philosophy and it reads something like this: the amount of matter or mass is a measure of the same thing that arises from its density and volume, which we can interpret as volume, and I also see that there is something wrong with the fact that it was Ernst Mac, a couple of hundred years later, who actually pointed out that Newton's formulation is unfortunate, since we can only define the density. like the mass of a unit volume, the circle is manifest and, by the way, in the corner there is a vicious circle, so Newton, who would hope to be the champion of clarity, his second law of motion is force equals mass for acceleration, these are concepts. that are deeply embedded in our common understanding of what is now known as classical physics and I would say that it is a physics that is simply consistent with our everyday observations: watching a tennis match, watching Andy Murray lose in the semifinal of the Open France. to Stan Wawrinka and you will have an idea of ​​the way in which the movement of the tennis ball is affected by a force watch a game of pool on television get in your car and accelerate at high speed along the m4 until you reach the first set of traffic cones and you'll have an idea of ​​what classical Newtonian physics is trying to tell you, but start picking through it and you'll find that some of the fundamental concepts that we're very familiar with start to unravel a little bit because, in truth , something as important and fundamental as mass was never properly defined in the first place.

Mark tried to define mass, but only in relation to other masses, there was no real attempt to come to a firm understanding of a derivation almost as to what mass is okay, so we have some problems that we don't have anymore with our understanding of the nature of atoms and we're a little wobbly when it comes to understanding what mass is, but let's stick with those two. The questions I started with at first seemed pretty simple. Surely we should be able to get some light at the end of the tunnel if we keep our heads down and move on.

Well, move on when you don't get clarity from the chemists from the physicists you can always trust the chemists and about a hundred years after Newton again, John Dalton wasn't the only one here. I am selecting and highlighting these heroes simply to summarize what was essentially a movement carried out by many individuals. involved in its development, but John Dalton said that he had come to an enlightened understanding of the nature of chemicals by observing their weights and actually understanding that he could understand chemicals in terms of the nature of the atoms they contained. So this is the beginning of a burgeoning understanding of chemistry and, in fact, if I'm honest, the foundations along with the development of the science of thermodynamics, the development of the beginnings, the seeds of the Industrial Revolution, Dalton was quite commercial when it arrived.

To understand the composition of water, as far as he was concerned, one of them was hydrogen and one oxygen atom. Antoine Lavoisier was not sure, but Antoine Lavoisier did not survive the French Revolution. I'm afraid he was guillotined for his efforts not for his scientific efforts I have to say but for his efforts as a tax collector and it took a little while after some confusion perhaps the clarifying voice was an Italian chemist called Stanislaw Karat Sorrow who in this quote makes it quite clear what he thinks the nature of the chemical has to do with the difference the different amounts of the same element contained in different triton molecules are all complete multiples that was the unique thing that the chemists were observing all the complete multiples of one and the same that always being complete has the right to be called an atom.

I love that quote and, of course, as a result of the work that was being done to understand the nature of the relationships between the constituents, the atomic constituents of different molecular substances, we came to the firm understanding that water is a molecule of h2o , okay, I won't tell you the amount of confusion created even around that simple understanding because of course if you take hydrogen as a gas, your instinct is to think it's a monatomic gas, it's a hydrogen atom if you take oxygen as a gas. , your initial instinct is to think of oxygen as a monatomic gas.

Oh but when H and O were combined to make water things didn't work out and it was just realizing that Mollick's hydrogen is actually a molecular gas, its h2 and oxygen is a molecular gas o2, combine them and then you can start figuring out how water can be water, so we've made quite some progress, this looks like, in fact, I think we're ready for a mission update, okay, so let's start with this. night with two very simple questions about this ice cube and as a result of efforts that began with the ancient Greeks two thousand five hundred years ago, we have understood that ice, being water, is made of round atoms with a weight that we have a lot. more sophisticated thanks to the efforts of the mechanical philosophers of the 17th and 18th centuries and the chemists of the 18th and 19th centuries, and we now understand that we can drill into ice as a substance and what we will find is a network of moleculesof h2o here the red ball represents an oxygen atom and the two small white balls represent hydrogen atoms, so ice is a regular network of water molecules that we write as h2o, where would we look then to find its mass?

Well, we can find its mass or its weight, I'm not differentiating the mass or weight of its hydrogen and oxygen atoms, but we have to remember the caveat, whatever it is, because we don't have a good definition of mass yet, okay , everyone is glad that we all knew better, but I'm sorry, I feel like I could have wasted 20 minutes of your lives going through things that you already know, but I think it's important that you understand the nature of the journey we're on, it's OK, so okay, let's move on. Fast forward a little further, now I see that the annoying physicists are back on the scene, they can't be trusted just at the time, in the early 20th century, when we were starting to get evidence of that atoms really existed, not just existed.

The product of a fertile imagination just at the time when we were getting evidence that atoms really existed, physicists were figuring out how to split them up. Honestly, I don't know, it shouldn't be trusted, and again, this is a model that should be very familiar. of the planetary model of the atom Rutherford did some experiments bombarding thin sheets of gold with something called alpha particles, effectively the nuclei of helium atoms, and was surprised to think that this was like shooting 15-inch projectiles at a piece of tissue paper , how amazing it was then. I found some projectiles bouncing towards it and what that simply meant was that the entire mass of a gold atom or any atom is really tightly concentrated in a small central nucleus and, in fact, we now understand that oxygen atoms consist of nuclei surrounded by orbiting electrons and those nuclei contain a total of 16 particles. 8 positively charged protons.

Eight neutrons. Neutral hydrogen is the lightest element on the periodic table. It consists of a single proton in its nucleus. Great, so it's time to update another mission. Well, we've gone a little further, okay, the physicists have meddled, but we've gone a little further, we now understand that, in fact, our water molecule can be imagined as oxygen nuclei sent to hydrogen atoms in a structure around which electrons are wrapped in orbit and is nature. from the way electrons wrap around these three atoms that create the molecular properties of something like water. Fantastic and even better news is that 99% of the mass of an atom is found in its nucleus.

Yes, we still don't know what mass. is, but we know where to look for it, that's good news, okay, we can worry about what will be next, okay, so our attention now turns to the nature of protons and neutrons in the nuclei of atoms, there it is where we search to find what we now know. what water consists of, we now know its atomic structure, we know its nuclear structure, we are going a long way to answering the first question, what is water made of, what is the IceCube made of and we believe that at least we are getting some clarity. and where we think we need to look to find its mass, okay, go on, oh, now I can't tell you what kind of mess this creates again just when you thought things were starting to become clearer, we get to this period of scientific endeavor where No we get nothing but madness and confusion, so we can credit Prince Louis, 5th Duke of Blois, for the idea that the discovery made by Einstein in 1905 What did Einstein discover in 1905?

He discovered that light waves can be particles we now know as photons. Louis Dubrow speculated that as a result of some additional observations in experimental science over the next almost 20 years, then perhaps it is also a possibility that electrons could be waves. Now we would always have entertained the idea, from the beginning of the speculations of the ancient Greeks, that being able to take material substance except that, ultimately, we must find an ultimate kind of indivisible matter from which everything is made and now we have this French French Prince telling us well, actually, you know what you thought were hard little billiard balls. material substance that turned out to be negatively charged electrons can also be waves why is this a problem?

Well, let's take a quick look. I just want to spend a few minutes talking about what I call the essential mystery of quantum mechanics. There is a famous experiment. It may already sound familiar to you, it's called the two-slit experiment and it's easy to understand what we see in the context of the wave theory of light. We take a light source, we take two narrow slits or holes and now we shine the light through them. There is only one caveat: the distance, the space between the slits must be of a certain magnitude and the slits themselves must be of the order of the wavelength of the light and the chances of you seeing what you need to see only if that light itself It is monochromatic in other words, it has a single wavelength, it is not contaminated with different colors, do that and what you see projected on a distant screen is what is known as the two-slit interference pattern, it is very easy to understand As the light waves make their way through the diffracting slits they extend further and into space beyond, where one wave crest collides with a wave crest coming from the other slit, you get what is known as interference.

Constructively, the waves add up to give a stronger wave where trough meets trough. Let's delve into constructive interference, but when the crest of a wave meets the trough of the wave, you get destructive canceling interference and the result is an alternating light and Frenchy pattern. These were first discovered by Thomas Young around 1804, easy to understand with a wave. The theory of light, but the debris now tells us that electrons can be waves, so how about we do that experiment with electrons and how about we do it in an arrangement such that only one electron passes through these two slits at the time?

Think about that. for a second an electron is an individual indivisible piece of is a fundamental particle the elementary particle has a negative electrical charge but it also has a mess whatever it is we anticipate that the electron must surely pass through one or the other of these two slits and the One One thing you don't expect to get is an interference pattern coming out of that, how is that possible? But the debris said that electrons can also be waves and a wave passes through both slits simultaneously to interfere on the opposite side, so let's do the experiment.

This is what we see when a few electrons have passed through these two slits. Alright. What we see is that for each electron we see a definitive point. It says that one electron hit here and that seems completely consistent with the idea that a single electron hit here. The electron maintaining its integrity passes through one of the other slits to be detected on the screen on the opposite side, so let's let in a few more electrons and a few more electrons and a few more now, although the resolution is a little blurry and this is not HDMI quality, we have the feeling that, although these electrons pass through this device one at a time, what we are seeing is an interference pattern of light and dark fringes.

What I love about this experiment is whether the electron actually passes through both. it cuts simultaneously like a wave what happens to its dough as it does it now I don't know how many of you are familiar with the work of Tom Stoppard, he wrote a play called Hapgood that was staged I think in the late '80s, 1988 or there about him having a character, Koerner, it was a play on the double agent in mi6, I think, but the double agent was a metaphor for wave-particle duality. Stop Art is a smart guy and Koerner said that every time we don't look we get a wave pattern because Of course, faced with that kind of perplexing experiment, you might be tempted to say, "Okay, well, I'm going to trace the path." of an electron through this thing.

I'll show you, but the moment you do it, every time we look to see how." we get the wave pattern we get the particle pattern the act of observing determines reality and that is the essential mystery. Okay, Einstein and Bohr had a famous debate. The problem with this kind of thing is that when we see a single point on the far screen there is a phrase that says that if the electron is described as a wave, it is distributed, it could be anywhere across that screen, it ends up being in a only place, it is detected there, but that place cannot be predicted, it is left to chance, it seems that way. the nature of quantum probability and Einstein didn't like it when he said that God doesn't play dice.

Bohr, on the other hand, of course responded that it is not our place to tell God how he should rule the world, so this is the mystery of quantum probability. Mechanics we were doing so well that we started with our ice cube, put water molecules in a regular lattice, found the mass of the water molecules in the nuclei of their protons and neutrons in their nuclei and now we stumble upon this. sea ​​of ​​confusion called quantum mechanics. I'm going to move on because, well, the thing about quantum mechanics is that it works very well, it's by far one of the best theories of physics ever devised, even though it's weird and no one understands it.

Do you think I'm kidding? ? No. There's an extension of quantum mechanics perhaps less familiar than some of these things called quantum field theory, and one of the first successful developments of quantum field theory was this guy, the charismatic American physicist. Richard Feynman, but there were others involved, Julian Schwinger, Sinha Taro Tominaga and an English physicist called Freeman Dyson, were responsible for putting it together. It's called quantum electrodynamics and the subtlety and sophistication of quantum electrodynamics is something to behold. I think Feynman once said that prediction. The things that can be calculated with quantum electrodynamics are like knowing the distance from San Francisco to New York within the width of a human hair.

It's so precise that you can't help but accept that this version of quantum field theory has some essential truth to it even though we don't understand it and that was fine, QED worked very well, but then when physicists Theorists began to gather 28 20 years after this, something called World War II intervened 20 years later, when theorists began to try to create a quantum field theory to describe protons and neutrons, they ran into a problem in the meantime, waves quantum, by the way, so we haven't lost the idea of ​​wave-particle duality in this we still have to deal with this confusion, it's just that those wave ideas have been translated into a field, it's still an extended distributed structure, still We have the problem of the collapse of the wave function, we still understand that in Truong the field somehow interacts with the screen and ends up producing a single point here in a way that cannot be predicted, there was a problem and that is that the first Quantum field theories dealt only with massless particles, now the photon is a good example of a massless particle and therefore having obtained clarity, although I use clarity probably in the reverse sense.

Commas having gained the clarity of quantum mechanics and quantum field theory, we now find ourselves in a situation where things have gone terribly wrong again and we have lost sight of the mass, we cannot arrive at the mass of the protons or neutrons, although we know that these things have mass, so what do we do right? The first thing we need to do is understand what a massless particle actually looks like, and to do that, I'm afraid I'll have to ask you to indulge me in a bit of Einstein's Special Theory of Relativity. I promise you no, it won't hurt too much, so here's a very simply conceived particle, it's a billiard ball type thing, it has a diameter, I called it d0, you're with me, okay, I'm going to push that particle. to travel, it travels with a speed V and I'm going to push that particle to move at increasing speeds up to the speed of light, which is given the special symbol C.

Right now, to understand what's happening, I need to recognize. One of the effects of Einstein's special theory of relativity is that distances contract and time dilates. Don't ask me to get into it now, but anyone who wants to buy me a beer later, I'll be happy to explain why that happens. So what we do is we push our particle, let's push it to something like 87 percent of the speed of light. This factor, given the Greek symbol gamma, is called the Lorentz factor. You don't have to worry about where it comes from or what it represents. you just need to know that it started with a value of 1 and now has a value of 2 and what it means according to that little equation ofup there means that the diameter of this particle in the direction of travel has been compressed by half. its original diameter, that's the special theory of relativity for you, it takes you a little further now, 98% of the speed of light, by the way, we're getting to the kinds of speeds that protons are launched at around the Large Hadron Collider at CERN. get up to about 99 percent of the speed of light, we now see that this Lorentz gamma factor moves to a value of about five, which means that the diameter of this particle is 1/5 of its original diameter in the direction in which it moves.

I think you can figure out what's going to happen if we take this up to the speed of light, we'll end up with the thing coming out of the top and we'll end up with effectively a two-dimensional, dimensionless particle. That makes sense now, in truth, we cannot accelerate, we cannot move particles with mass at the speed of light, only massless particles can travel at this speed, it is a characteristic and by the way, massless particles only traveled At the speed of light. Okay, so what that means is that a massless particle traveling at the speed of light is flat or two-dimensional, it's kind of lost the third dimension, it can't possibly exist in a third dimension, and in fact, for those Of you who know about the polarization of light, you will know that light actually has only two states of polarization which we can consider perhaps as vertical and horizontal.

There is no polarization of light in this direction. If it's light traveling towards you, I always say horizontal when I do that and then vertical vertical. or horizontal there is no polarization in this direction for the very simple reason is that it does not have a third dimension to travel in which a container to polarize is fine, so that is a problem, so in fact, solve this problem in quantum field theory in the early 1950s what the need is a trick, we need massless particles to come in, we need something magical to happen and we need mass particles to come out, you know what it is, it's called the Higgs field and The fundamental particle of the Higgs field is something called the Higgs. boson, here's a dirty little secret about theoretical physics.

If you are a theoretical physicist sitting pondering big thoughts about the nature of material substance and elementary particles, your mission is to make mathematics work correctly, that is your first priority. that the math works in a way that is consistent with the theoretical structures above and hopefully in such a way that it can give you some ideas about an experimental test you can do or something to look for in a lab like CERN. but these theorists are not too concerned about what it means and then when these things turn out to have a bit of life, it means that we are left struggling to try to understand what this means to the extent that they are concerned they have a mathematical trick they invoke something called Higgs field and suddenly the mass activates as a result of what is supposed to happen, believe it or not, politicians are baffled by this, and if you can think Those of you who are old enough went back to another conservative government which actually ultimately became a minority Conservative government under John Major in the 1980s.

John Major had a science minister called William Waldegrave and William Waldegrave was faced with the challenge of understanding whether it was worth it for the UK to continue financing the European Center for Nuclear Research (CERN). I think in those days we spent about £50 million on CERN and of course the message I was getting from high energy physicists: "We need to find the Higgs boson" and William Waldegrave. said it, tell me what the hell this is on an A4 piece of paper and I will give the best contestant a bottle of vintage champagne as a reward and he got a lot of entries and he actually got a lot of good entries, but maybe the best one will come. from a guy called Professor David Miller, near here at the University of College London, who said: well, maybe you think of it this way, imagine a singularly important personality in Conservative Party politics.

Thatcher was gone but let me tell you she was still a force to be reckoned with and imagine we have a room here full of conservative party workers this is the Higgs field now the fracture is two dimensional and massless walk into this room of the Higgs field and immediately the field begins to gather around it because we all want to listen. What she has to say, we're waiting for her to rule on, you know, political political decisions, the big political decisions of the day, and as a consequence of this clustering of the field around a massless particle, her motion is impeded. .

It didn't travel across the room at the speed of light it was traveling at before and as a consequence it has now acquired mass, it's an imperfect analogy, but William Waldegrave liked it, that's how the Higgs field gives mass to elementary particles. The Higgs boson itself, well the Higgs boson is like a whispered rumor, of course this is clearly a controversial thing, we don't want everyone to hear this, so as the rumor circulates around the room , the party workers are grouping together to listen to what he says and that movement, that grouping of the field itself is the Higgs boson, everything is absolutely clear now, well, then, actually, you know the story, there was a search for the Higgs boson, was discovered or found in 2012.

Incredibly, I had a book about this discovery in stores just six weeks after the discoveries were announced. I had an agreement with my editor. I will write a 95% finished book, which you will then print and then we will wait. I actually listened to the webcast live from CERN on the morning of December 4th. In July 2012, I finished the chapter and the book was, as I say, in the store six weeks later. I thought it was pretty cool, but completing the search for the Higgs boson completes the standard model. Now, this is effectively the particle physicist's equivalent to the periodic chemist. table these are the ingredients we ultimately need to arrive at our current and contemporary understanding of the nature of matter, we don't need all of this, although that's the good news, we can reduce it to just a few bits, what we need are two things called up and down quarks these combine in triplets of three to form protons and neutrons, so protons and neutrons are no longer elementary particles in themselves, we already need these things called gluons, these gluons literally stick to physicists, They really have limited creativity at the end of the day when they come up with these names, it's usually pretty obvious what they're referring to, so gluons bind quarks inside protons and neutrons, we need electrons, obviously, electrons follow being what counts for most of chemistry and molecular biology in the At the end of the day, we need them and they form patterns around the outside of atomic nuclei.

The force that holds electrons and nuclei together is the electromagnetic force and that is a force that is carried by photons, familiar particles of light that we also know. I need this thing called the Higgs boson because the Higgs boson has to do with the Higgs field and the Higgs field. The Higgs field is necessary in the standard model of particle physics for particles to get dirty properly. Mission update: are we ready? So we learned that the ice cube consists of a network of water molecules h2o we learned that an oxygen atom has a central nucleus with 8 protons 8 neutrons hydrogen atoms have a central nucleus each of 1 proton we drilled into the proton itself Me I'm glad everyone wasn't running away screaming from now we have a real problem because one would hope that if we can trace the history, the map, the mass of a substance like an ice cube, its molecules, its atoms, its atomic nuclei, its protons and neutrons, and we learn that protons and neutrons are composed of quarks, as might be expected.

Well, those quark masses come from interactions with the Higgs field. Let's not dwell too much on the fact that they have a mass. We know what it is, but when we do the sums we find that mass of a proton only 1% of the mass of a proton is explained by adding the masses of its two up quarks and one down quark something seems to have gone terribly wrong fortunately there was a guy named Einstein and wrote an article in 1905 you know what Einstein's most famous equation is, everyone knows that equation, right? Perhaps you would be a little disappointed to know that in his unique 1905 paper on this aspect of special relativity that equation does not appear at all in what Einstein discovered his great idea is not actually equal to MC squared, it is this M equals a E over C squared.

Mass is the measure of the energy content of a body. Now I have to tell you. I mean, who remembers the Quatermass experiment on BBC television all those years ago? smiles in the audience, yes, a kindred spirit that remembers video footage of atomic explosions in the 1960s, 1970s, scares you to death as these bombs get bigger and bigger, you take the catch for a uranium core , a nucleus of uranium-235 and one fifth the mass of a proton. becomes the energy of an atomic explosion, you have this almost cultural understanding that e equals mc-squared represents the vast reserve of energy that is somehow locked up in mass and when you convert mass into energy as was done towards the end of In the Quatermass experiment you get this enormous release, but that was not Einstein x' in even though e equals mc-squared became the best-known equation in the entire history of physics, so this is What's really going on: It's math, Jim, but not as we know it, the mass (about 1% of the mass of a proton, say, comes from interactions between otherwise massless quarks and the Higgs field that , by the way, is all around us, if it didn't exist, if it somehow magically went out. we'd all explode fine and not in a spectacular explosion look, but we'd all get out, all of our particles would lose mass, there'd be no mechanism to give them mass, so you expect the Higgs field to stay on, okay? comes from the energy of the interaction of these Higgs field particles, but it is only 1% of the total sum, where the rest is.

Most of the proton's mass comes from the energy of the blues dancing back and forth between the quarks holding Together, gluons are massless particles, but they possess very, very high energy and once they are enclosed In the confines of a proton or a neutron, that energy is translated into what we understand and perceive as a mass front, we will check who one is. of the architects of the Standard Model worked on something called quantum chromodynamics, which is the theory that describes quarks and gluons. Put this way, if the body is a human body whose overwhelming mass arises from the protons and neutrons it contains, the answer is not clear. and decisive the mass of that body with 95% accuracy is its energy content.

I would like to do something about the energy content of a certain part of my body, but so far I haven't come up with a diet that would actually turn off the Higgs field only in this specific region, but who knows, I'm hoping, this It's this massless mass and I'm struggling to try to find a way to articulate this in the book. I said look, mass hasn't been a property since the ancient Greeks. I have always understood that atoms would have weight, weight or mass, being an intrinsic or primary property of these indivisible and indestructible pieces of substance, but now we learn that mass is not actually a property, it is not something that matter has, it is rather a behavior, it is something quantum.

The fields do it now, this is not the end, the standard model of particle physics has many explanatory holes, the only thing it does not do is not explain, for example, gravity and at the moment there is a lot of effort. From the work being done both in the string theory community and in another area called loop quantum gravity to try to come up with a quantum theory of gravity, there may still be more to learn, however I'm pretty sure that Our understanding of matter and the nature of mass is not going to change as a result of these efforts, so get used to the fact that when you step on the scale in the morning, you are weighing the energy content of the gluons locked inside the protons and neutrons. of your body.

Don't know. yes that will make a difference in what the scales were sir, but sometimes a little lighting is a good thing now I want to thank you that I have lasted a little longer than I intended. I want to thank Carlo Rovelli, an Italian Theorist, who very kindly agreed to read the manuscript over my shoulder and make sure he didn't get any laughs. Ah, Jenny Phil, who is in the audience, our people at Oxford University Press, who helped me turn my ramblings into a book that I hope will belegible, my mother, good. We should all thank our mother, right?

But my mother, who turns 80 this year, I have to tell you that she has infinite curiosity. When she was seventy years old, she decided to study history at the University of Warwick, something he partially did. Time blessin and she agreed to read the manuscript and came back saying Jim, why do you have to use all these big words? Can't you make it a little simpler? Which I tried to do. Martin Davis, who introduced me. Thank you very much for. asking me to come tonight and of course to you for being so patient, thank you very much.