Q&A: The Concept of Mass - with Jim Baggott

Hello, thank you very much for the talk and you were talking about those elementary particles that have no more

mass

than those that have no

mass

, but in their graph there was a reference to the mass being 1/3 and 2/3 and 0 and that's right, it's okay. There shouldn't be any contradiction, but let's go back to the picture, well, let's stick with this one, so actually, you're right, this little graph shows a couple of things, the properties of these elementary particles, one of them is mass. given in obscure things units called mega electron volts divided by C squared, but that's nothing more than Einstein's m is equal to E over C squared again, so it's an energy divided by C squared, so what you have They are the energies, yes indeed, from above and below. quarks, but you also have things called charges.

I didn't go into this because I didn't want to get bogged down in too much detail, but we are used to thinking of a proton with a single positive charge, an electron with a single negative charge, well, protons made up of quarks, the quarks themselves have fractional electric charges, two up and down, it's two times two-thirds of a charge minus one-third of a charge, which gives a single positive charge, and finally, they have something called spinning all matter. particles have a spin of 1/2, they are called fermions again, it doesn't really matter what that means, but it means that when they spin they have to spin twice to get back to where they started, it's very easy to understand, okay, there you see. they are numbers gluons and photons have 0 0 1 0 meaning they have no mass so these are massless particles they have a charge of 0 and they have a unit of spin they only have to spin once to get back to where they started well and the The Higgs boson It has a large mass, has no charge and has no spin.

It is one of the so-called scalar particles. That answers the question: the masses of up and down quarks in particular are very, very difficult to pin down. the way there's a lot of jiggery-pokery and it's required effectively, what you're doing is if you think about the picture that I showed you of accelerating that particle to the speed of light when you have two protons colliding with each other. at the Large Hadron Collider they crash into each other not like cannonballs, but almost like flat plates, so think about what happens, that means that the quarks embedded in those protons are like little current stuck to those plates and, like As a result, by investigating the consequences of such collisions, theorists can get an idea of ​​what the masses of the up and down quarks really are, but they are pretty good figures, there is some margin of error, and they are well below what we think.

Ultimately I need to explain the mass of the proton or neutron. Thank you young man in the middle of the microphone. I just wanted to ask if that dark energy has anything to do with this. Okay, so I had a choice tonight. I can talk about matter and mass on an effectively microscopic scale that gets smaller and smaller, you know, atoms and nuclei, or I could talk about matter and mass on a cosmological scale, the universe as a whole. Your question related to dark energy relates to what happens in the universe as a whole. It was discovered in 1998 as a result of making observations of supernova explosions.

We know that the universe is expanding, but it was understood that that expansion began at the Big Bang and, you know, the rate of expansion would slowly decrease. It is slowly declining, but was discovered in 1998 as a result of making these observations; In reality, the expansion of the universe is accelerating, it is expanding faster than we anticipate and that can only be for one reason and that is because space-time is not empty. It has some things that we don't understand and when physicists don't understand something they tend to call it obscure. I think we probably grew up with Star Wars or something, it's the dark force, so they call it dark energy.

The universe is full of dark energy or, if you're familiar with the term, it has a positive cosmological constant, which was Einstein's famous manipulation factor from 1917, so dark energy is something that makes up about 70% of the universe. total mass energy of the universe. Yeah, we don't know what the other question you might have is, of course, about dark matter. Now, dark matter is again somewhat hypothetical, it arises from observing the large-scale motions of galaxies and current understanding, but it is always a controversial trend. What I understand is that in the early stages, shortly after the expansion of the Big Bang universe, we had matter, we don't know what it is, that's why it's called, it doesn't interact with anything, which is another reason it's called dark, but we know it. it has gravitational effects and if it had not been for the dark matter that forms what are known as halos that clump together and concentrate the matter that we know and care about baryonic matter, the protons and neutrons and then the atoms at the center of these halos, they would never have been stars. and galaxies, so fortunately if dark matter really exists we owe it a lot because we wouldn't be here if it didn't exist but we don't know what it is it's not there in the standard model of particle physics there's no particle we can point to and say look there's matter dark that we don't know, so I haven't answered your question, but at the moment it has nothing to do with the version of events that I have given you, which is about piercing the nature of substance inertial masses mass no no no I'm not being no I'm not being I'm not kidding there is there was as you can see Newton never gave a satisfactory definition of mass and actually even if I used Newton's second law, forces mass multiplied by acceleration and use that to try to define the mass that It's still circular because we needed to define force in the first place, mass is best understood as the inertia of an object, and again, I haven't given it much thought.

Of course, the big difference between weight and mass is that weight is what we get as a result of making measurements of the Earth's gravity, but mass is something intrinsic and largely independent of gravity, so when you see images old stories of moon landings and astronauts bouncing as if they were on the moon and suddenly falling into a kilometer spin because they realize they can't actually move or spin quickly because they still have inertia even though they weigh much less in the moon because the moon's gravity is much weaker, so it is understood that inertia is a property directly linked to the mass itself, but we still do not know what it is and, increasingly, if Einstein's conclusions are accepted, mass is equal to C squared, so we're mainly talking about mass, inertia. of energy, not even the inertia of mass, so the answer to your question is that there is an argument that says we don't know what inertia is, or we can't really define mass, so by definition we can't really define inertia. very good anyone I also like not being able to explain things thank you the question more questions have gone to this side of the room very curious on this side obviously you already know everything so can we quote a character in a book who explained that? the act of observation generates its own reality, if you will, it crystallizes the nature of something, yes, we discovered the Higgs boson by shooting particles at other particles, crashing them into each other and poof, we have discovered the Higgs boson we were looking for. it really happens in nature and if it doesn't, it surely means that there is no active observation, there is no exposure, the intriguing thing is that the discovery of the Higgs boson, interestingly, was not about the Higgs boson.

I know it sounds like that. an anachronism, but it was the Higgs field, the Higgs boson was the last telltale proof that the Higgs field really exists, it really exists now that the Higgs field, if honestly, if it weren't present throughout the universe, We really wouldn't. be here to some extent, since we have shown that the Higgs boson really exists, the Higgs field really exists at least again as far as our current understanding is concerned, then we understand that you know the large scale properties of the visible universe in terms of the presence of that field in answer to your question, yes, so the purpose of particle colliders like the Large Hadron Collider is to create collision energies high enough to cause these particles to come out of hiding.

You're right, you know. In a vacuum of empty space there are not necessarily Higgs bosons constantly appearing and disappearing. There is a caveat that I want to make about this, but nevertheless, certainly, very, very soon, the energies of the collisions at the Large Hadron Collider In fact, if you can also think of them this way, they turn back the clock to some of the first stages, a billionth of a second after the Big Bang, which, by the way, I think is quite amazing, a billionth of a second after the Big Bang. and what the Higgs field would have done is triggered a divergence between something called the electroweak field into two distinct forces, electromagnetism and something called the weak interaction, and again, if it hadn't then happened a billionth of a second after the Big Bang, Once again , I wouldn't be here debating the finer points, so it's not about having some kind of esoteric game with nature where we produce these, but they don't actually exist anywhere, these things are betraying the secrets of nature What are they. telling us that this so-called Higgs field really exists and that we can explain a lot of what we see today in terms of the existence of that field, thanks for the back in the green shirt, yeah, yeah, I'm just going to ask. one earlier in the talk, this is you, you talked about the wave, the slit wave experiment, yeah, and you said just think about the fact that it's an electron going through the slit, yeah, can you expand on that because I understand that has mass as it has to do with the fact that, well, you know, the understanding that this is a very contemporary debate.

I happen to be in Oxford on Saturday giving a talk on the nature of quantum reality, this is what I do in my spare time and I want to be absolutely clear, I'm not trying to not answer your question, but this is very much a contemporary debate that still continues ninety years after quantum mechanics was first discovered. What exactly is happening? Is this wavefunction or this field real? Does it really have a real physical interpretation? If you accept that it does, then you are torturing yourself thinking about what is happening to the mass and how the mass is taken out of the field when there is an interaction and what triggers that interaction.

How come it's random? Well, you know what the nature of quantum probability is. Lots of really difficult questions. I would say even philosophical questions. The other route you can take is the route that Niels Bohr actually took in his famous debate with Einstein. That is, in fact. his quote I can, I can give it to you out of nowhere, he argued that there is no quantum world, there is only an abstract quantum physical description, it is a mistake to think that physics tells us what nature is like, physics refers to what we can Well, that's what I call an anti-realist interpretation, but it basically says that the whole structure of quantum mechanics is simply a very, very convenient, albeit very complicated, way of encoding information that allows us to predict the future based on the past. .

The moment you hit people who want to manifest some sense of physical significance in some of the

concept

s and equations of quantum mechanics, is the moment you think and then start worrying about questions like what happened to their mass, What happens in the collapse of? The Einstein wave function argument, the God of him doesn't play dice, was actually about appreciating how something that is distributed can. You know, I'm doing these kinds of hand gestures, but the experiments have been that we're spread out on a different island off the coast of Spain. 140 kilometers away, so we were, we're not talking about this kind of distance, we're talking about huge distances where entangled quantum effects can still be seen and tested experimentally, so we know this is correct the moment you start to get your Head over to some of these is the moment you start to get a headache trying to understand what he is trying to tell you.

Well, if the mass of the gluon is zero, does that mean that it suddenly stops interacting with the Higgs field as soon as it doesn't try to hold the quarks together. An interesting question, I don't know, is the short answer, because because gluons have a and quarks have a very unique set of properties, no one has ever seen a single quark, no one has ever seen a single gluon during the simple reason. It's that the force that occurs inside the proton that holds these quarks together is not like a force that you are familiar with. We tend to think that, say, the electromagnetic force or the force of gravity decreases with distance.

Well, it's older when it gets closer. to the source of the electric charge or the source of the electromagnetic field and decreases with distance, the strong force carried by gluons does not work that way, in fact the strong force is weakerwhen the two quarks are close together it starts to activate as you try to pull these quarks apart think of the quarks as being tied together by two really very strong springs as the quarks go back and forth between the quarks when you try to pull these quarks apart now What happens is that when you start mining, if you can try to extract a quark from a proton for example, the energy to do that starts to increase so much that they actually pull kunja particles out of the vacuum of nothing.

I can explain that mechanism, but that will require several pints of beer and you seem too young to buy new points of view. and that's the problem, so you know you never see a quark without a companion, the moment you start mining a quark, you can do these kinds of experiments at the Large Hadron Collider, you never see a single quark, no one has never seen a fractional electric charge. Stephen Weinberg, who kindly wrote a foreword to my book on the Higgs, actually explained that the reason he never talked about protons and neutrons in a seminal paper he wrote in 1967 that ultimately won him the Nobel Prize was because He didn't believe in quarks, so it's a really difficult thing for future physicists to understand, but now there's more and more enough evidence. to explain some of the things we see at the Large Hadron Collider as if quarks and gluons really exist, so there is good evidence to believe in them, but we have never seen them individually and that is really what happens inside a proton, energy. involved in the binding of these quarks is so high that that is why it represents 98-99% of the mass of the particle at the end of the day.

Great, we have a few more questions. I'm very aware that I've only heard from men tonight, so if it's just women who have any questions, I've noticed there are some young women here. My wife is committed to diversity and inclusion. I am very interested in hearing from anyone who is not white. man like me or him or everyone else and spoken thank you okay I'm a little curious how voids fit into this so obviously you can have energy and electromagnetic waves flying through a vacuum but there's no mass , so I'm wondering if that means this. there is no Higgs field there is mass there is mass I think we have actually come to an understanding in contemporary theoretical physics and in experimental physics that we have real difficulties with the

concept

of the word vacuum, in reality there is really nothing about space -time that can be empty there is always something in it at least there is a Higgs field in it at least there is something called the Heisenberg uncertainty principle which is a cornerstone of quantum mechanics and the central principle and Heisenberg has a very history , very long, very, very short, allows particles to fluctuate in and out of existence, appearing and then disappearing and they are allowed to do so as long as the energy they take from empty space is returned within the space. time prescribed by Heisenberg's uncertainty principle, so even in empty space there is still the notion that we have virtual particle fields coming in and out of existence, so there is no vacuum;

In fact, in many ways Aristotle was right all along, nature abhors a vacuum. so think about empty space, there is this dark energy, the question behind it is that the cosmological constant energy is somehow manifesting in space itself, it is pushing spacetime causing spacetime to expand, if you can understand That, then you have the Higgs field and you have virtual particles, you start to realize that there is a lot going on in the vacuum, so we have time for a couple more questions. I'm sorry we don't have a microphone in the gallery, but if anyone up in the gallery wants to ask a question, please shout it out and I'll try to repeat it to the rest of the audience.

Somebody right there I can see it sir, I can hear it, yes, I think the Greeks had it. true, absolutely true, what you have to do is accept that also in accounting you need to include energy, now it is the energy of something and in this particular case it would be the energy of quantum fields, so to a certain extent the Greeks were absolutely They were right and they were right in saying that I simply cannot split something into absolutely nothing, the best I can do is split something into the energy of its quantum fields. Epicurus would never have understood it, but that's one way of interpreting what he had to do anyway.

Let's say that at the beginning, gentlemen, the front here has been waiting very patiently. I think that's probably our last question. I guess I was just wondering if they would melt their ice cube, yeah, to add energy to what's happening to the model. Do you have more glue today or are you talking about them tearing and building energy well? So there are a couple of ways to think about the answer to that question, first of all, when you add energy to induce something called a phase transition in this particular case, we miss a solid and a liquid, you have to put energy in to overcome The forces you couldn't really see, but if you come back to my wait, yeah, no, then what are you doing?

I mean, possibly yes, you're increasing the weight, but it's very, very small, in a very small way, so you see these little dashed lines that represent something called hydrogen bonds that hold hydrogen atoms and oxygen atoms together, you know. , in a correlation that is what blocks them. the lattice, that's why it's called something called lattice enthalpy, in effect, what you do is break those little dashed lines and the water molecules dissolve. Yes, you are putting energy, but you are putting energy to overcome something. We're making trades so the energy doesn't come out, since that latent heat is the phrase I was actually looking for, maybe I only have time for one more, so no, you had a question.

Do you normally want to be a little cheeky? Those questions. Hopefully the phone is sliding a few more times, they won't, so your estimate of nothing comes out of nowhere. Obviously there wasn't the creation of a Big Bang long before that, well that depends on who is willing to believe what they read. so let's be realistic. I wrote a book published a couple of years ago called Origins, which effectively attempted to trace the scientific story of creation from the Big Bang to the origin of human consciousness. This is what I do in my free time. and I basically said that there are three gaps in our current scientific understanding, of course, the first is the Big Bang itself.

We extrapolate our current physical scientific theories back to the very beginning of everything and those theories, by definition, fall apart so we can It doesn't explain the beginning, the second explanatory gap is the origin of life on planet Earth and the third is possibly what it is. consciousness, much less the origin of consciousness, although there are some good ideas about where it arises from, however, one of the problems with the current Big Bang model is that it invokes or implies something called the singularity, it is where everything comes together. compresses to infinite density, infinite energy and zero, well, in fact, space-time is born in that explosion of things that explodes and we get the universe as we know it today, however, if so, that is a consequence of something called Einstein's general theory of relativity, spacetime is now so curved, if you like, it has become infinitely curved and that is what a singularity is, but Einstein's relative general theory is a theory. of classical physics is not a quantum theory and the moment you start trying to link the idea of ​​quantum theory with gravity is the moment you run into the idea that actually maybe there is no singularity, the singularity infinity does not exist in nature, so there is no singularity what you get is a compressed residual fragment of space-time that some theorists now call the Big Bounce, so if the universe existed before and collapsed, it would have collapsed to a very, very high density, but not to zero or infinite density and then the universe bounced from that position again now it's all very speculative, somewhat even metaphysical, but that's where a quantum theory of gravity will eventually take you, so who knows, I won't do it on that note, just wrap up tonight's evening before thanking our speaker again.

He forced me to remind you that there are copies of Jim's latest book that will be available outside. I'm sure if you ask him nicely, he'll also write his name on it the traditional way and yes, that's still it. Me to thank you all for coming and many thanks to Jim for a fascinating talk, thank you.