Please more video content from professor Tong! He possesses the rare gift of radiating enthusiasm and excitement for things that are often left hidden away behind a wall of technical words, mathematical intricacy anda seemingly impregnable stock of foreknowledge! These videos and his lecture notes are golden.
David Tong seems very passionate about Quantum Fields. If the lumps of quantum fields truly do make up matter as we know it. it really does matter for the development of future technology like matter creation machine. instant cheese burgerz. yes, you can haz cheese burgerz little kitty. if you can press this button here.
@@MrBlue-km8qv except you can't create matter, it would violate the energy conservation principle. You can only change matter to energy and vice versa, but from einsteins equation we know that 1 unit of mass which is about one proton, takes 931 million electron volts of energy, and that's a huge amount
That same guy that devoted his life to studying "the dust" also happens to be a theoretical physicist, I suppose. I am also wondering how big are these dusts; are they quantum mechanical dusts or classical dusts? In other words how large or small are they?
Brian may the musician earned a PhD in astrophysics, and his dissertation was on dust particles in the universe well more within our solar system Which makes you think Queen: another one bites the dust Well looking for graviton ideas
Hey RI; thanks for the video. It would be great if when he refers to slides in the questions, or also in the main presentation with his laser pointer, that you put that fullscreen with the pertinent information underlined. Thanks
I think these are recorded live and not edited. Using a high power laser (dangerous) pointer, mouse or joy stick pointer that appears on the screen goes a long way toward clarity. And then show the presenter the same screen you give us, so the presenter can't point at something we can't see.
and replace the laser pointer with accelerometers, etc and have that talk to the laptop showing the slides and paint the pointer on the image itself. Then, once the undergrads have done that, spin the technology off as a company :3
Came from the brilliant lecture and even his QA session works wonders. Going look around for more David Tong lectures. Pure passion and excitement. I flippin' love it.
Not to be an asshole, but is there a possibility in the future to see where his laser pointer is pointing? I love these lectures but it would help a dummy like me follow along lol. Thank you! It's been for a great privlage to watch these lectures!
I found that infuriating too, i really want to know what he is pointing to, if he could instead isolate the part of the equation he is talking to and put just that up onto the screen it would be more clear to the audience watching online. Amazing talk, very grateful for it, but we viewers are missing those parts because we can't see the laser pointer.
Folks round these parts don't take kindly to those usin words like infuriating. Y'all are just a li'l annoyed. Your effrontery is exasperating, and I am enraged!
I too was discombobulated by this elementary incongruity, given the level of scientific brilliance being displayed that they haven't yet figured out how to use a laser that will show up on a video. Maybe anything that it would show in the video would have overcome the light making the image itself visible to the folks in the darkened room? I bet there is a way! : )
thank you , have listened to this lecture about 6 times over the last year as am not a physicist and have enjoyed immensely and its getting clearer and am able to absorb it more, wonderful, wish I had had more enthusiastic physics teachers,
I know little about quantum physics, but dang, Prof. Tong managed to hypnotise me into staying the entire session, enwrapped, AND wanting it not to end. The man is fascinating, what more can I say!
This lecture was incredible. Had me captive throughout, you can feel the passion and enthusiasm radiating from David, and it makes me so grateful that my past self decided to take the right educational steps into pursuing a maths degree, studying quantum field theory. It's hard and painful, but hearing talks like this reignites my motivation. Thank you, David Tong, and The RI.
Really like Prof Tong's answer that the solutions of QM equation are discrete but the underlying fields are themselves continuous. However there are many who would argue that our reality comes through in those solutions only, when we observe the system of QM states (collapsing to a single observable quantum state), and we cannot ever know the underlying continuous nature of a system much less our universe.
The ideas he explains and those of mystics seem more or less the same in terms of difficulty level. However fell in love the way he talks and puts his heart in the topic
My compliments. Due to their engraved statement, every word and every term can be precisely understood. A pleasure to listen. The perfect didac-tics and presentation and the choice of location are superfluous to men-tion for tautological self-conviction reasons An original german speaking listener, Dr. Schwund. Thank you very much. Mein Kompliment. Aufgrund ihrer gestochenen Aussage lässt sich jedes Wort und jeder Term präzise verstehen. Ein Vergnügen, zuzuhören. Die perfekte Didaktik und Präsentation und die Wahl der Location erübrig sich ja zu erwähnen aus tautologischen Selbstüberzeugungsgründen. Ein original deutsch sprechender Zuhörer, Dr. Schwund. Thank you very much
As an observation - he would make a fantastic Dr. Who... and would probably be able to create his own Tardis and be able to put it in an old fashion British style phone both... Love his presentation and lecture... All the (continued) VERY BEST!
This was a good one! He delivered his talk really well, and with obvious engagement with the subject. He's obviously a scientific 'radical', but someone has to be or there are no spikes on our sphere of knowledge to give us traction and keep us moving. We're not talking a flat-earther or a time-cube here.
I was thinking according to relativity no frame of reference is "correct" hence the earth is round relative from space and flat relative from earth ;) -except it isn't since we see an approaching ship mast first-
This talk did raise me a question: Is there any theory that specifically describes, or tries to, the way all fields interact with each other? We have intrinsic features of each field like spin and charge and magnetic moment, but can we consider then as manifestations of interactions between fields. Could we “dismantle” each feature and understand the fundamentals of their emergence?
Michael Faraday had it right . His Field the "Aether" composed of (Electro magnetic wave frequency range, from cosmic background/Radio to Visible Light, to Gamma, to Black Hole Singularity) got hijacked , Now Called Quantum field/foam/ Higgs field/whatever. All these other fields are only various manifestations/measurements of intrinsic features of Faraday's Field. Not separate fields but features of the one.
I have a question, for any of you geniuses out there :) From what I understand, light is simply another one of these vibrations, in the electromagnetic field. So is there anything special about the EM field that makes it's rate of propagation the fastest? Or is it the case that the speed of light is actually just the rate of propagation in all fields, but the photon is the only particle we know that has no mass, so is able to reach that speed? In other words, how does the speed of light (and if you really want to go for it, special relativity effects that go with it) fit in to all this?
Any massless particle travels at c in a vacuum. Incidentally this is how we know that neutrinos have mass: we observe oscillation (neutrinos turn into muons and vice versa), so we know that they're not travelling at c (because then time dilation would mean that they were immutable).
Captivating! One thing, though, not mentioned are all the parameters to the standard model and how theories we have to derive them from fewer parameters. I guess that would probably take a series of videos and not just one.
David Tong is a great speaker because he has the intellect of a great theoretical physicicst. He illiterates way more complex stuff in his theories (most likely), and he is genuinely excited about what he is discussing. Like myself in my comments on this video and others. See my science stuff in my comments.
Yeah, I was really struck with his enthusiasm and his excellent presentation. Now looking for more videos of him just because I loved this talk of his so much. 😛
"We don't really know if there is a 'before the Bang'. It's possible that Time started there. It's possible that there was a Time before. It's just beyond what we currently know." - David Tong.
Fascinating. My understanding of Quantum Mechanics was that fields are generated by particles, not the other way around, but I suppose that's my classical training fighting modern Quantum understandings (or not understandings 😉 ). Also, QFT would better explain the particle wave duality concept with photons and merely just extend the scope to all fundamental particles. Makes sense. Anyway, I love Feynman and how genius he was in his way of describing incredibly complicated mathematics with squiggly lines and funny names. Truly a legend with a fantastic sense of humor and humbling understanding of the insane complexity of the reality of the world around us. God does indeed play dice...the next question is, I suppose, are the dice loaded? 😂 Anyway, thank you to the Royal Institution and all you do for science and scientific awareness. The Christmas Lectures are some of my favorite things to watch! ❤
So what is anti-matter? If all particles are a simple ripple in the quantum field, is anti-matter a ripple with a negative or opposing amplitude that cancels the other out? If so, where does the intense energy emitted from the mutual annihilation come from? What causes the 'negative' ripple in the quantum field? I would have loved to ask this question.
My speculative hypothesis is that the quantum fluctuations power every subatomic and QM process. Essentially, time is measured by the quantum fluctuations, and then measured by subatomic processes. And gravity is less of a distortion of space-time, but rather a distortion of the quantum field powering it. In fact, I am in the camp that there's probably only one unified quantum field and this explains why time dilates at great speed or by large mass. My thinking goes that the energy required to manifest the phenomena that we eventually term particles at some level of abstraction is derived from the quantum fluctuations. But those fluctuations while seemingly random are occurring at a relatively uniform density in space. Therefore, as the quantum vacuum energy is utilized to manifest either large mass or to manifest mass at high velocity, it drains the available vacuum energy density in the localized/regionalized areas. That draining causes a perceived warping of spacetime, but the warping itself is an illusion. It's not actually warping, just the available vacuum energy density diminishes such that the subatomic particles and processes emerge spatially closer to more abundant available energy density. The small effect accumulates at scale to a large warping effect. Photons, massless particles, still require energy from the quantum vacuum to propagate, and thus their trajectories are bent towards more available energy. Gluons moving at great speed additionally do just the same, but because their path is chaotically confined, they just slow down relative to the rest of the universe in effect causing a cascade of every other subatomic processes to slow which appears as if time itself slows down. The gluons MUST slow because they must await the replenishment of quantum vacuum energy at the rate available despite the decreased density because of all the adjacent mass and subatomic activity draining it just as well. So, my idea essentially puts time into the conceptual bucket as being derived solely from the energy density replenishment within the quantum vacuum. It also sees spacetime distorting as just illusionary, when in effect it's actually the particles/processes bending as a result of a very slight energy thirst/attraction towards areas of space with a higher replenishment rate and available energy. And that if large amounts of mass or velocity (energy) can distort what we view as spacetime when using GR, maybe any large amount of energy such as heat, dense electric current, or luminous density could as well. It would effectively drain the well of available quantum vacuum energy enough to affect localized subatomic processes and thus distortion what we perceive as spacetime. A massive laser might be able to bend spacetime as just a massive density of photons, or using a laser to create a massive amount of heat to distort as well. The constant for the speed of light is really a reference to the rate of quantum fluctuations, or rather a measure of the universe's entropy with regards to the quantum vacuum energy replenishment availability. Time is derived from the vacuum. Just my thoughts. Still formulating it. I'm just trying to look at this from a different perspective. I had the idea for quantum fields before I knew what they were. I didn't believe particles exist. I felt like they were just like eddies in a turbulent flow of a quantum-scopic fluid. This is long before I started studying QM in better detail. So I'm feeling a bit lucky right now. If you have any ideas, questions, comments, or you can point out a flaw, please let me know.
Be more mathematical. I think adjectives like thirst and replenishment are useless. If there is a mathematical formulation that works then that’ll become the theory we don’t need “reasons”. Yang mills theory is the conception to derive force interactions from the quantum vacuum fluctuation . It’s not an original idea, it’s yang-mills bro. I believe it’s considered the correct integral for describing all forces except gravity, the integral is just so hard we can’t solve the integral. And I believe with gravity, where the field is space time, it’s not even just that the integral becomes really really hard. It’s just the wrong integral because GR has rigidities like black holes that are just incompatible and produce infinities. With quantum gravity yang-mills may just have mathematical parallels. What’s going on is just the purely mathematical exercise of coming up with approximations that don’t produce infinities such as perturbation theory, Path Integral formulation, loop quantum gravity?, 2D Liouville field theory, etc…Again, all of which are just mathematical approximations to avoid infinities- OR there can be an attempt to change the entire formulation so that we don’t run info infinities and can solve the correct integral I guess. So this is Ofcourse string theory. I thing your naïveté can be summed up as why do you think string theory which requires 11 dimensions or whatever even exists. GR and time are empirically fundamental which is maybe surprising and just actually realize mathematics is a thing. I’m so confused r u studying QFT in uni?
@@letsmakeamovie2037 I think String theory exists because physicists are having trouble looking at the experimental data and trying to reconcile it with their existing paradigm of particle and quantum physics. String theory is just a creative approach using math to attempt to describe it. I think it's honorable, but probably incorrect. I think physicists need to take a completely new look at everything and leave nothing to assumptions. Replenishment referenced the rate at which energy would bubble into existence and out of existence. If perturbations such as matter are draining the energy that popped into existence locally, then the quantum vacuum locally is truly void of everything. The idea would be that like the Casimir effect, gravity would emerge from this subtle spatial shift caused by mass creating a flow of quantum vacuum energy towards the large mass. Similarly, time itself slows down, but not the ticking of time, just every physical process above the layer of abstraction of the quantum vacuum energy. So subatomic processes would slow as they await the quantum energy to become available again, or rather the rate at which the energy pops into existence is constant but it gets utilized by matter at a faster rate which then must slow down and match the local rate. Denser matter requires more energy than the quantum vacuum produces per unit of (absolute) time, and therefore the matter itself slows down, all of the subatomic processes slow down. Cesium clocks, slow down. So there is neither a warping of space nor a warping of time, nor relative observers. There's just an absolute frame of reference and the relativity is an illusion produced by the rate at which quantum vacuum energy gets utilized by the matter requiring it faster than the quantum vacuum allows it to pop into existence.
@@Hexnilium isnt that just called starting with Hilbert space. What’s the new idea? How is it original? Draining energy is synonymous with vacuum entanglement. Ok. Deriving relativity topology with entanglement is seriously popular already (the math isn’t understood though)
@@letsmakeamovie2037 That there are no spacetime distortions. That they are illusionary. Relativity works like how Newtonian physics works, but it's incorrect.
It is a brave scientist that says "zero probability" on an emerging counter-intuitive piece of research. Just look at Einstein and Bhor and their antithetical views :) An excellent lecture on a fascinating topic, followed by a great Q&A. Thank you RI!!
It's impossible according to the equations they use to assert it exists. Also, the force generated has always been within the noise levels of the experiments. It's smart to ask, but it's simply not relevant to this topic. This wasn't a lecture on how the scientific method works, but rather on a specific theory, and according to all known theories and all known models that make the universe understandable, that machine should not have the proposed and not yet measured. effect
David, the Schrödinger equation is at best an incomplete, non relativistic description of reality and on top of that it predicts the quantization of many properties of the atom: Energy levels, angular momentum, etc... all quantized, discrete properties. There are more fundamental structures (yet to be properly described) underlying the reality of fields (and excitations): Spacetime cells, quantum gravity structures, the vacuum structure in general. It is too soon to know if these objects are discrete but based on the clues, many of us suspect they are.
Yeah, but the Greeks were not *ALL* atomists. There were also monists, such as Anaximander who argued that, at the base level of all things, there is only one thing. Everything that exists is, at base level, the infinite and eternal in itself. This is referring to his concept of the Apeiron, the "unbounded" or "limitless," which is completely indefinite (or non-discrete, as quantum physicists might say; it does not have physical form of its own). It is from this Apeiron that opposites emerge, such as hot vs. cold, wet vs. dry, light vs. dark, etc. He also stated that everything is destroyed when it goes back into the Apeiron, such that in nature, there are an infinite number of "worlds" being created, but they are all destroyed again just as quickly as they are created, because the opposites come together, back into the Apeiron, which appears to be creating void, or what the ancient Greeks often referred to as "chaos." Essentially, to them, void and chaos were pure possibility, or potential, undefined and without form. Another pre-Socratic, Parmenides, literally stated that nothingness, or void, cannot exist. There is necessarily something, even in nothing, since either something does exist or it does not exist, but whatever exists cannot not-exist, and whatever does not exist cannot exist. So, existence itself exists. Therefore, it cannot not-exist. The nonexistence of existence is void. Therefore, no void exists. Essentially, that is what he argued. How, exactly, are either of them wrong, considering quantum fields? Obviously, Anaximander is using language that does not fit with the standard model, but the essence of his theory is that all things are one thing at the base level, but not at higher levels (those coming about due to opposites, like movement vs. no movement, heat vs. no heat, light vs. no light, ect.). The same is true of Parmemides; it is just that Parmenides says the basic essence to the universe is the "thing" of existence itself, rather than the Apeiron, or the "unbounded," as Anaximander says. They seem right, in a certain sense.
LOL! Totally looks like him doesn't he! I feel like we've watched him grow through the RI questions sections. Definitely a smart kid, although going to every RI lecture probably helps.
I had a thought experiment about the big bang, the big bang singularity is just like every other we see at the centre of galaxies, but with enough mass to create a universe, in my thought experiment, black holes are cold on the inside, but not absolute zero, until the mass exceeds a specific amount, the gravitational pressure stops vibration of energy at the centre, then cascading convection occurs in some catastrophic manner.
I Got it and keys finall find from you ..Wonderful sir you are among millions sir 🙏🙏 Mr David tong and team word by word understood 👏👏 spectacular knowledge video leads directly like Rocket 🚀 like this was and is speed .. 👏👏
I would have had a few interesting questions (as a nobody in this area really): 1. There seems to be only one generation of the Higgs field, has this anything to do with it being scalar...and if so, is that not a hint where the generations in other fields come from? 2. This interaction between parallel fields by various forces that too are fields, but connect them, has it a resolution and if so is there some sort of grid/alignment that affects the interactions?
I enjoyed watching. i got two questions 1) how do particle entanglement experiment fit in quantum field theory? 2) the force (if icall it so) that caused the big bang could it be the same force causing the universe to accelerate (dark energy)..... since no breaks have been applied to counter it so far. thank u
Entanglement is a result of the integral and partition thingy that he didn't explain. :) From what I understand, the maths involved are easier to understand using quantum mechanics, however.
I don't like the idea of a moment in time( the idea of a beginning of the universe) were t=0 . In fact when i imagine o.oooo etc . and i put as many zeros behind as the number of quarks that are present in the universe , then i could still write a 1 after it . so in my opinion there is no time=0 . It is in fact an asymptote , it nears infinitely close to 0 but it will never become zero .
Shot in the dark, very very theoretical but still a serious question. We only discovered the Higgs field four years ago. Its theorized that there are fields of 'spiritual' origin that we are currently unable to detect. Would you, David, hypothesize that the field nature of quantum mechanics leaves room for interpretation of these 'spiritual' aspects to the universe that we seem unable to prove with modern science?
While the wave function is continuous, it seems unreasonable to conclude from it that nature itself is continuous when the physically meaningful solutions are discrete. It’s curious that more physical reality is assigned to the mathematical model than to the outcomes it predicts as making sense physically-especially when considering the paradoxes of infinite divisibility. It's like attributing physical existence to the Real line
A QUANTUM FIELD ISN'T LIKE A CLASSICAL MAGNETIC, ELECTRIC OR GRAVITIONAL FIELD. A QUANTUM FIELD IS JUST A MATHEMATICAL TOOL USED TO DESCRIBE "REALITY".
This is probably because of my lack of knowledge in the subject but it occurred to me that all the problems with finding a gravity field is that gravity is a just a feature of the material of space-time and that perhaps all the other fields are emergent from the material of space-time in the same way that all the known particles are emergent from the fields.
Miguel Rivera in that same sense if spacetime is the field of gravity then the other fields are other fabrics of other dimensions? ;) Joking aside if space time is the field of gravity perhaps the graviton is the quanta of spacetime though that may also be from my lack of understanding
Firstly, the gravity field does exist, and they transfer speed of that field has been quantified. Recently I might add, and just a few days after the machines were turned on. What is harder to characterize is the structure or orientation of the field. Why they assume gravity isn't just some 'feature' of stuff residing in space, has to do with photons. Photons react to gravitational distortions in space time, but not are not themselves manipulated by gravity because they have no mass. Meaning a photon (energy traveling at the speed of light) will travel at the speed of light forever. (By measuring billions years old light from far away stars). That's what the gravitational lensing shows. The photons wants to travel their course through space-time, but gravity, though it can't affect the photons, can affect space. This ability of some things to disobey gravity while other things must, implies a field with some associated characteristic that lets the field manipulate it. If nothing obeyed gravity, we'd not be here; if everything obeyed gravity, the universe might exist, but would almost certainly appear different. Light itself would eventually slow, and get pulled into the nearest dense object, and the universe would look perpetually 'young' and our apparent horizon would be much smaller. Only few old stars, and close, filling up the sky. It's the disharmony of field interactions that makes interesting things happen.
Nima Arkani Hamed says something like, Fields are ONLY a mathematical model - you can do field redefinitions, so they can't be fundamental. Geiger counters go blip, blip, blip not waaaeeeeaaaaeeee (detect particles, NOT waves). Schrodinger's equation does NOT explain what happens, only probabilities of what could happen in the future. It is about our ignorance, not about reality. That said, I've seen a couple of Professor Tong's QFT class videos, and he seems brilliant.
"Geiger counters go blip, blip, blip", I don't think that is related to how many particles it is detecting, if that was the case then it will do a continuous beep as there would be so many particles, even in an extremely low radiation area
My question :Is quantum fluctuation a fluctuation of energy? May the energy fluctuation cause the fluctuation of space-time curvature according to the Einstein field equation? The difference of curvature means the difference of gravity which seeds the formation of galaxies.
My question that I ask with the naivety, arrogance and stupidity of a child: could it be possible that the particles are granular but that the continuousness emerges from the quantum uncertainty aspect of the particle? In other words, the particle is singular, however it's existance is distributed like a continuous field and this is what makes the "smoothness" of the fields..
Stupidity of a child? Childs always ask the right questions, I'm always impressed. But concerning your question (which isn't stupid at all): There is neither granularity nor smoothness in the quantum world. In fact, there aren't even particles, that could be granular or smooth. That's disturbing, depressive, and spooky at the same time. Maybe you know from school, that light is as well a particle as a wave. You can do one experiment and prove, that it behaves like a water wave, and another, where it is made of lots and lots of bullets. The same thing goes for every kind of matter, let's say an electron. We can easily describe it as a particle, but you can also show, that it can interfer just as a wave. So when you enter the world of quantum mechanics, everything is described by the Schrödinger equation as a wave function. Then you have this big Heisenberg uncertainty principle, which means, that you can't know a particles place and it's momentum at the same time. So once a (particle-)electron stops, it can't be granular anymore, and eitherway. Then, there comes the quantization. In Quantum Field Theory, we call it the second quantization, so the field itself is quantized. So bye bye, smooth field. Particles aren't more than peaks in this field, everything is entangled. It's not, that we look at a pointy object through a milky lense, it's just by nature a really weird object, that we'll never be able to imagine. Very impressive though, that in our macroscopic world, there is so much order and beauty.
Good question, this was how it was thought of when Faraday first proposed the idea of a field. Maxwells equations (which come in part from Faraday), part of what they tell you is that an electric charge (e.g. an electron) will produce an electric field and moving electric charges produce magnetic fields. So in this context the field is emergent from the particle. The particle stayed the fundamental constituent of nature until the late 1920s/1930s whereby Physicists started trying to form a theory that respects special relativity and quantum mechanics. The only way this was possible without running into contradictions was if you placed the field as the fundamental constituent of nature and the particle (the quanta of the field) being emergent. Going back more towards your question, this was pondered by Richard Feynman: en.wikipedia.org/wiki/One-electron_universe.
Questioning the nature of Nature rather than questioning the nature of assumed matter gives a different perspective. Doesn't the emergence of discreteness from the continuous show the existence of both? Language including mathematics creates unnatural paradoxes reflecting dual aspects of natural phenomenon.
Was hoping someone would ask if the standard model equation could explain the results of the double slit experiment. Or maybe that's a stupid question, or I missed something.
You don't need as complex physics as the standard model to explain the double slit experiment. That experiment is much more insignificant than you think and is just a result of the statistical/wave properties of sub-atomic particles.
It's pretty clear that continuous is only an approximation of discrete. You fill a bucket with sand. How much sand is in the bucket ? You could count the grains, but it's easier to say "about two kilograms".
that's a pretty specific example, and i could just easily flip it on its head, and say that discretisation is an approximation of continuity. for example, think about how you talk about "where" something is. you could chop space up into small cubes and say that the object is in one of those cubes; but it's more fundamental to talk about where the object is on a continuum. perhaps space is quantised, but it wouldn't be in a strict sense like the above example.
Tesla understood the quantum gravity(though he wouldn't call it that), it's why he wrote Einstein a letter letting him know he was close but wrong. Also, there is no graviton.. It's all about resistance and attraction, push and pull like magnetics, friction and culmination of forces, like he said at one point, collective behaviors.
Fantastic talk!! I have a question on the age of the universe: how can we discuss of the absolute time passed after the big bang if we know that time is relative, and depends on the speed of the observer?
"Solving the equation is extremely difficult". I wonder if this will become easier once we have quantum computers because of their inherent continuous nature. Currently there are some commercial quantum computers that can solve very narrow optimazation problems in field equations.
@@ramanunnikrishnan7354 multiple companies have done it. The question is how many qubits it has and how long they can stay in a quantum state and how stable they are. If you have to run every equation 1000000 times just to be able to "trust" the result, it might not be worth it :)
Does space hold the Universe apart, as it appears in the Field of Relativity OR does the space bind the Universe together, as it appears in the Quantum Field? Is this either A or B or is it both?
i know right? tunneling is proving to be incredibly common in all sorts of organisms. although, i would guess he was playing it safe here? or maybe interpret that quantum effects can't be observed macroscopically? still strange, though
Physicists can you please correct me in thinking the quantum field fluctuations could be the consciousness of nature. Could this be or am I inventing a psuedo science that can be proven against. Fascinating lecture and q & a thank you
Based on my little understanding, if you bring the concept of consciousness among these so-called fields, it will no longer belong to quantum theories, rather being discussed in the field of metaphysics and philosophy, i could be wrong, but this is how I think it will be :)
I think there is alternative approach to looking at space-time nature of universe, What if time is not even a factor in this whole scenario. We are observing the hypothesis as an observant who is evolved in to take the time as discrete measurement unit. There are many persons living who does not perceive the nature of time at all. If we take from their point of view nature of events is as it is; the state of matter changes, What if gravity/strong/weak force influence the matter state change (accelerate/accelerate) in its own sphere so that it seems different to observer outside. We should look into effect of forces on matter change in different way rather than putting time into factor.
Unfortunately the speaker's references to "this" when cursoring over various parts of the equation aren't clear because we cannot see in the provided video which portions of the projector screen his pointer is moving over.
don't believe ever watched a video where the presenter was so conversant and approachable in such an exotic subject.
It definitely is exotic i would say! And yes i greatly appreciate his approachableness!
rick mayal of physics. same energy
Genius
Agreed
I wish he was my instructor when I was taking physics in college.
Please more video content from professor Tong! He possesses the rare gift of radiating enthusiasm and excitement for things that are often left hidden away behind a wall of technical words, mathematical intricacy anda seemingly impregnable stock of foreknowledge! These videos and his lecture notes are golden.
Who else is in love with David Tong's style? Bring him baaaaaaaack.... again and again, please.
Why did this have to stop!! Absolutely fantastic lecture.
Especially the Q&A!!! They're like the comments section of an online article or essay...or video!! XD
David Tong seems very passionate about Quantum Fields. If the lumps of quantum fields truly do make up matter as we know it. it really does matter for the development of future technology like matter creation machine. instant cheese burgerz. yes, you can haz cheese burgerz little kitty. if you can press this button here.
@@MrBlue-km8qv except you can't create matter, it would violate the energy conservation principle. You can only change matter to energy and vice versa, but from einsteins equation we know that 1 unit of mass which is about one proton, takes 931 million electron volts of energy, and that's a huge amount
This is an excerpt. He does a very long talk on this.
@@meliacogan1586 Do you happen to have a link? I'd love to see more.
Excellent lecture and Q & A session. I look forward to more lectures by Professor David Tong.
The humility of the lecturer is really something to behold
That's just amazing to see the intellectual excitemen of the David Thong. He's really encouraging young scientist. That's the way, that's the way!
"Dust"...and the one guy in the history of the world who devoted his life to studying it, dashing the hopes of theoretical physcists worldwide!!
That same guy that devoted his life to studying "the dust" also happens to be a theoretical physicist, I suppose. I am also wondering how big are these dusts; are they quantum mechanical dusts or classical dusts? In other words how large or small are they?
@@kiswahilikitukuzwe2547 I'd say that "quantum mechanical dust" are particles, not dust anymore. Dust is dust, like sand grains
Brian may the musician earned a PhD in astrophysics, and his dissertation was on dust particles in the universe well more within our solar system
Which makes you think Queen: another one bites the dust
Well looking for graviton ideas
Hey RI; thanks for the video. It would be great if when he refers to slides in the questions, or also in the main presentation with his laser pointer, that you put that fullscreen with the pertinent information underlined.
Thanks
I think these are recorded live and not edited. Using a high power laser (dangerous) pointer, mouse or joy stick pointer that appears on the screen goes a long way toward clarity. And then show the presenter the same screen you give us, so the presenter can't point at something we can't see.
and replace the laser pointer with accelerometers, etc and have that talk to the laptop showing the slides and paint the pointer on the image itself.
Then, once the undergrads have done that, spin the technology off as a company :3
Came from the brilliant lecture and even his QA session works wonders. Going look around for more David Tong lectures. Pure passion and excitement. I flippin' love it.
Not to be an asshole, but is there a possibility in the future to see where his laser pointer is pointing? I love these lectures but it would help a dummy like me follow along lol. Thank you! It's been for a great privlage to watch these lectures!
I found that infuriating too, i really want to know what he is pointing to, if he could instead isolate the part of the equation he is talking to and put just that up onto the screen it would be more clear to the audience watching online. Amazing talk, very grateful for it, but we viewers are missing those parts because we can't see the laser pointer.
Folks round these parts don't take kindly to those usin words like infuriating. Y'all are just a li'l annoyed.
Your effrontery is exasperating, and I am enraged!
@@brinx8634 haha :D love it
Tong is a master lecturer, behold and and appreciate.
I too was discombobulated by this elementary incongruity, given the level of scientific brilliance being displayed that they haven't yet figured out how to use a laser that will show up on a video. Maybe anything that it would show in the video would have overcome the light making the image itself visible to the folks in the darkened room? I bet there is a way! : )
thank you , have listened to this lecture about 6 times over the last year as am not a physicist and have enjoyed immensely and its getting clearer and am able to absorb it more, wonderful, wish I had had more enthusiastic physics teachers,
David Tong is the greatest speaker. Just amazing.
David Tong is a good Speaker!
Must appriciate his knowledge and confidence to explain such a complex topic...
I know little about quantum physics, but dang, Prof. Tong managed to hypnotise me into staying the entire session, enwrapped, AND wanting it not to end. The man is fascinating, what more can I say!
I wish this Q/A session never end
...Excellent Q/A session by Dr.David Tong.
This lecture was incredible. Had me captive throughout, you can feel the passion and enthusiasm radiating from David, and it makes me so grateful that my past self decided to take the right educational steps into pursuing a maths degree, studying quantum field theory. It's hard and painful, but hearing talks like this reignites my motivation. Thank you, David Tong, and The RI.
Really like Prof Tong's answer that the solutions of QM equation are discrete but the underlying fields are themselves continuous. However there are many who would argue that our reality comes through in those solutions only, when we observe the system of QM states (collapsing to a single observable quantum state), and we cannot ever know the underlying continuous nature of a system much less our universe.
What a wonderful speaker and topic. I love his style: friendly, direct, informed, but taking no prisoners :).
The ideas he explains and those of mystics seem more or less the same in terms of difficulty level. However fell in love the way he talks and puts his heart in the topic
My compliments. Due to their engraved statement, every word and every term can be precisely understood. A pleasure to listen. The perfect didac-tics and presentation and the choice of location are superfluous to men-tion for tautological self-conviction reasons An original german speaking listener, Dr. Schwund.
Thank you very much.
Mein Kompliment.
Aufgrund ihrer gestochenen Aussage lässt sich jedes Wort und jeder Term präzise verstehen. Ein Vergnügen, zuzuhören. Die perfekte Didaktik und Präsentation und die Wahl der Location erübrig sich ja zu erwähnen aus tautologischen Selbstüberzeugungsgründen.
Ein original deutsch sprechender Zuhörer, Dr. Schwund. Thank you very much
As an observation - he would make a fantastic Dr. Who... and would probably be able to create his own Tardis and be able to put it in an old fashion British style phone both... Love his presentation and lecture... All the (continued) VERY BEST!
Long Answer; Yes with an 'if'
Short Answer; No with a 'but'
I have found a new favorite physicist. This is a good day
There must be a noble prize give to that person who will solve that exponential terms including integration and other terms of that equation..
i think i found this as the best lecture on quantum fields
This guy is on top of his game!
Great talk and presenter!
He's possibly the best science presenter.
This was a good one! He delivered his talk really well, and with obvious engagement with the subject. He's obviously a scientific 'radical', but someone has to be or there are no spikes on our sphere of knowledge to give us traction and keep us moving. We're not talking a flat-earther or a time-cube here.
I was thinking according to relativity no frame of reference is "correct" hence the earth is round relative from space and flat relative from earth ;)
-except it isn't since we see an approaching ship mast first-
6:37, Harry Potter has questions about QFT
To be more specific that should be Harry James Potter-Evans-Verres
@@acrm-sjork haha, a fellow Methods of Rationality fan! Yes sir, you are right!
Thanks for publishing this most enjoyable talk!
This talk did raise me a question: Is there any theory that specifically describes, or tries to, the way all fields interact with each other? We have intrinsic features of each field like spin and charge and magnetic moment, but can we consider then as manifestations of interactions between fields. Could we “dismantle” each feature and understand the fundamentals of their emergence?
Michael Faraday had it right . His Field the "Aether" composed of (Electro magnetic wave frequency range, from cosmic background/Radio to Visible Light, to Gamma, to Black Hole Singularity) got hijacked , Now Called Quantum field/foam/ Higgs field/whatever. All these other fields are only various manifestations/measurements of intrinsic features of Faraday's Field. Not separate fields but features of the one.
Sire David Tong simply too class my favourite Professor!
I feel very lucky for getting to this video. Delicious stuff!
Thanks for the engaging discussion.
I have a question, for any of you geniuses out there :)
From what I understand, light is simply another one of these vibrations, in the electromagnetic field. So is there anything special about the EM field that makes it's rate of propagation the fastest? Or is it the case that the speed of light is actually just the rate of propagation in all fields, but the photon is the only particle we know that has no mass, so is able to reach that speed?
In other words, how does the speed of light (and if you really want to go for it, special relativity effects that go with it) fit in to all this?
Any massless particle travels at c in a vacuum. Incidentally this is how we know that neutrinos have mass: we observe oscillation (neutrinos turn into muons and vice versa), so we know that they're not travelling at c (because then time dilation would mean that they were immutable).
Excellent, my perception just went up up. David Tong is my new favourite science communicator. I wonder if he has a brother called Pete?
Captivating! One thing, though, not mentioned are all the parameters to the standard model and how theories we have to derive them from fewer parameters. I guess that would probably take a series of videos and not just one.
David Tong is a great speaker because he has the intellect of a great theoretical physicicst. He illiterates way more complex stuff in his theories (most likely), and he is genuinely excited about what he is discussing. Like myself in my comments on this video and others. See my science stuff in my comments.
Yeah, I was really struck with his enthusiasm and his excellent presentation. Now looking for more videos of him just because I loved this talk of his so much. 😛
"We don't really know if there is a 'before the Bang'. It's possible that Time started there. It's possible that there was a Time before. It's just beyond what we currently know." - David Tong.
We should ask Chuck Norris.
@@marcelweber7813 Chuck Norris caused the Big Bang when he was working out with his punching bag.
Fascinating. My understanding of Quantum Mechanics was that fields are generated by particles, not the other way around, but I suppose that's my classical training fighting modern Quantum understandings (or not understandings 😉 ). Also, QFT would better explain the particle wave duality concept with photons and merely just extend the scope to all fundamental particles. Makes sense. Anyway, I love Feynman and how genius he was in his way of describing incredibly complicated mathematics with squiggly lines and funny names. Truly a legend with a fantastic sense of humor and humbling understanding of the insane complexity of the reality of the world around us. God does indeed play dice...the next question is, I suppose, are the dice loaded? 😂
Anyway, thank you to the Royal Institution and all you do for science and scientific awareness. The Christmas Lectures are some of my favorite things to watch! ❤
This is even better than the lecture!!
You are one of the best i have ever heard. No match to your talk.
Thank you so much for this lecture. Great speaker.
The beak on the first guy is award winning
09:30 "Is there anyone up in the Gods have a question?" that sounded funny. 'Yes!', said God. he he
Can you explain how Self organising, self stimulating property can induce life like properties! Certainly a miracle!
So what is anti-matter? If all particles are a simple ripple in the quantum field, is anti-matter a ripple with a negative or opposing amplitude that cancels the other out? If so, where does the intense energy emitted from the mutual annihilation come from? What causes the 'negative' ripple in the quantum field? I would have loved to ask this question.
Finally honesty.
I'm dying to see one these live. Maybe vacation 2020
2020 is dead man
Nah we don't talk about 2020 with hope
Wait a min....who are you ?
A time traveller...
@@raghav9o9 I saw through the quantum field
@@ZacZabel 🙃🤔😆
Really Great Lecture. I loved every moment of it. About that "Dust..." - Is this a new branch of big bang scatology? If so - I'm all in.
My speculative hypothesis is that the quantum fluctuations power every subatomic and QM process.
Essentially, time is measured by the quantum fluctuations, and then measured by subatomic processes.
And gravity is less of a distortion of space-time, but rather a distortion of the quantum field powering it.
In fact, I am in the camp that there's probably only one unified quantum field and this explains why time dilates at great speed or by large mass.
My thinking goes that the energy required to manifest the phenomena that we eventually term particles at some level of abstraction is derived from the quantum fluctuations. But those fluctuations while seemingly random are occurring at a relatively uniform density in space. Therefore, as the quantum vacuum energy is utilized to manifest either large mass or to manifest mass at high velocity, it drains the available vacuum energy density in the localized/regionalized areas. That draining causes a perceived warping of spacetime, but the warping itself is an illusion. It's not actually warping, just the available vacuum energy density diminishes such that the subatomic particles and processes emerge spatially closer to more abundant available energy density. The small effect accumulates at scale to a large warping effect.
Photons, massless particles, still require energy from the quantum vacuum to propagate, and thus their trajectories are bent towards more available energy. Gluons moving at great speed additionally do just the same, but because their path is chaotically confined, they just slow down relative to the rest of the universe in effect causing a cascade of every other subatomic processes to slow which appears as if time itself slows down. The gluons MUST slow because they must await the replenishment of quantum vacuum energy at the rate available despite the decreased density because of all the adjacent mass and subatomic activity draining it just as well.
So, my idea essentially puts time into the conceptual bucket as being derived solely from the energy density replenishment within the quantum vacuum.
It also sees spacetime distorting as just illusionary, when in effect it's actually the particles/processes bending as a result of a very slight energy thirst/attraction towards areas of space with a higher replenishment rate and available energy.
And that if large amounts of mass or velocity (energy) can distort what we view as spacetime when using GR, maybe any large amount of energy such as heat, dense electric current, or luminous density could as well. It would effectively drain the well of available quantum vacuum energy enough to affect localized subatomic processes and thus distortion what we perceive as spacetime.
A massive laser might be able to bend spacetime as just a massive density of photons, or using a laser to create a massive amount of heat to distort as well.
The constant for the speed of light is really a reference to the rate of quantum fluctuations, or rather a measure of the universe's entropy with regards to the quantum vacuum energy replenishment availability. Time is derived from the vacuum.
Just my thoughts. Still formulating it.
I'm just trying to look at this from a different perspective.
I had the idea for quantum fields before I knew what they were.
I didn't believe particles exist. I felt like they were just like eddies in a turbulent flow of a quantum-scopic fluid.
This is long before I started studying QM in better detail.
So I'm feeling a bit lucky right now.
If you have any ideas, questions, comments, or you can point out a flaw, please let me know.
Be more mathematical. I think adjectives like thirst and replenishment are useless. If there is a mathematical formulation that works then that’ll become the theory we don’t need “reasons”.
Yang mills theory is the conception to derive force interactions from the quantum vacuum fluctuation . It’s not an original idea, it’s yang-mills bro. I believe it’s considered the correct integral for describing all forces except gravity, the integral is just so hard we can’t solve the integral. And I believe with gravity, where the field is space time, it’s not even just that the integral becomes really really hard. It’s just the wrong integral because GR has rigidities like black holes that are just incompatible and produce infinities. With quantum gravity yang-mills may just have mathematical parallels. What’s going on is just the purely mathematical exercise of coming up with approximations that don’t produce infinities such as perturbation theory, Path Integral formulation, loop quantum gravity?, 2D Liouville field theory, etc…Again, all of which are just mathematical approximations to avoid infinities- OR there can be an attempt to change the entire formulation so that we don’t run info infinities and can solve the correct integral I guess. So this is Ofcourse string theory. I thing your naïveté can be summed up as why do you think string theory which requires 11 dimensions or whatever even exists.
GR and time are empirically fundamental which is maybe surprising and just actually realize mathematics is a thing. I’m so confused r u studying QFT in uni?
@@letsmakeamovie2037 I think String theory exists because physicists are having trouble looking at the experimental data and trying to reconcile it with their existing paradigm of particle and quantum physics. String theory is just a creative approach using math to attempt to describe it. I think it's honorable, but probably incorrect.
I think physicists need to take a completely new look at everything and leave nothing to assumptions.
Replenishment referenced the rate at which energy would bubble into existence and out of existence.
If perturbations such as matter are draining the energy that popped into existence locally, then the quantum vacuum locally is truly void of everything.
The idea would be that like the Casimir effect, gravity would emerge from this subtle spatial shift caused by mass creating a flow of quantum vacuum energy towards the large mass. Similarly, time itself slows down, but not the ticking of time, just every physical process above the layer of abstraction of the quantum vacuum energy. So subatomic processes would slow as they await the quantum energy to become available again, or rather the rate at which the energy pops into existence is constant but it gets utilized by matter at a faster rate which then must slow down and match the local rate.
Denser matter requires more energy than the quantum vacuum produces per unit of (absolute) time, and therefore the matter itself slows down, all of the subatomic processes slow down. Cesium clocks, slow down. So there is neither a warping of space nor a warping of time, nor relative observers. There's just an absolute frame of reference and the relativity is an illusion produced by the rate at which quantum vacuum energy gets utilized by the matter requiring it faster than the quantum vacuum allows it to pop into existence.
@@Hexnilium isnt that just called starting with Hilbert space. What’s the new idea? How is it original? Draining energy is synonymous with vacuum entanglement. Ok. Deriving relativity topology with entanglement is seriously popular already (the math isn’t understood though)
@@letsmakeamovie2037 That there are no spacetime distortions. That they are illusionary.
Relativity works like how Newtonian physics works, but it's incorrect.
@@Hexnilium ok everyone agrees that relativity is wrong. So doesn’t everyone agree.
Answer to the first question, he refuses to accept granular reductionism. A man after my own heart!
I'd like to see more physicists talk about entanglement and Juan Maldacena's work.
It is a brave scientist that says "zero probability" on an emerging counter-intuitive piece of research. Just look at Einstein and Bhor and their antithetical views :)
An excellent lecture on a fascinating topic, followed by a great Q&A.
Thank you RI!!
It's impossible according to the equations they use to assert it exists. Also, the force generated has always been within the noise levels of the experiments. It's smart to ask, but it's simply not relevant to this topic. This wasn't a lecture on how the scientific method works, but rather on a specific theory, and according to all known theories and all known models that make the universe understandable, that machine should not have the proposed and not yet measured. effect
David, the Schrödinger equation is at best an incomplete, non relativistic description of reality and on top of that it predicts the quantization of many properties of the atom: Energy levels, angular momentum, etc... all quantized, discrete properties. There are more fundamental structures (yet to be properly described) underlying the reality of fields (and excitations): Spacetime cells, quantum gravity structures, the vacuum structure in general. It is too soon to know if these objects are discrete but based on the clues, many of us suspect they are.
Yeah, but the Greeks were not *ALL* atomists. There were also monists, such as Anaximander who argued that, at the base level of all things, there is only one thing. Everything that exists is, at base level, the infinite and eternal in itself. This is referring to his concept of the Apeiron, the "unbounded" or "limitless," which is completely indefinite (or non-discrete, as quantum physicists might say; it does not have physical form of its own). It is from this Apeiron that opposites emerge, such as hot vs. cold, wet vs. dry, light vs. dark, etc. He also stated that everything is destroyed when it goes back into the Apeiron, such that in nature, there are an infinite number of "worlds" being created, but they are all destroyed again just as quickly as they are created, because the opposites come together, back into the Apeiron, which appears to be creating void, or what the ancient Greeks often referred to as "chaos." Essentially, to them, void and chaos were pure possibility, or potential, undefined and without form.
Another pre-Socratic, Parmenides, literally stated that nothingness, or void, cannot exist. There is necessarily something, even in nothing, since either something does exist or it does not exist, but whatever exists cannot not-exist, and whatever does not exist cannot exist. So, existence itself exists. Therefore, it cannot not-exist. The nonexistence of existence is void. Therefore, no void exists. Essentially, that is what he argued.
How, exactly, are either of them wrong, considering quantum fields? Obviously, Anaximander is using language that does not fit with the standard model, but the essence of his theory is that all things are one thing at the base level, but not at higher levels (those coming about due to opposites, like movement vs. no movement, heat vs. no heat, light vs. no light, ect.). The same is true of Parmemides; it is just that Parmenides says the basic essence to the universe is the "thing" of existence itself, rather than the Apeiron, or the "unbounded," as Anaximander says. They seem right, in a certain sense.
Who's the kid with the glasses who always asks questions?
That's Harry Potter from Hogwarts.
LOL! Totally looks like him doesn't he! I feel like we've watched him grow through the RI questions sections. Definitely a smart kid, although going to every RI lecture probably helps.
It's funny because hes actually a wizard... Dont believe? do some research on the occult side of cern.
A scientist in the making
I had a thought experiment about the big bang, the big bang singularity is just like every other we see at the centre of galaxies, but with enough mass to create a universe, in my thought experiment, black holes are cold on the inside, but not absolute zero, until the mass exceeds a specific amount, the gravitational pressure stops vibration of energy at the centre, then cascading convection occurs in some catastrophic manner.
I Got it and keys finall find from you ..Wonderful sir you are among millions sir 🙏🙏 Mr David tong and team word by word understood 👏👏 spectacular knowledge video leads directly like Rocket 🚀 like this was and is speed .. 👏👏
I would have had a few interesting questions (as a nobody in this area really):
1. There seems to be only one generation of the Higgs field, has this anything to do with it being scalar...and if so, is that not a hint where the generations in other fields come from?
2. This interaction between parallel fields by various forces that too are fields, but connect them, has it a resolution and if so is there some sort of grid/alignment that affects the interactions?
getting rid of time and replacing it with quantum space lattice fluctuations in a spin network now seems like the best option
If you do that, will my wrist watch still work? :-)
@@RangerStrike anything with mass is a clock so probably, especially if it has and incabloc spring and is self winding
What possible significance does the term "fluctuations" have, without a function of time?
I doubt we can ever get rid of time; It just is, in a way
The think I hate about the RI is that their lectures don't go on forever. What am I supposed to do the rest of the night?
Oh you. We'll let you in on a secret, there's nearly 300 of these bad boys - ua-cam.com/play/PLbnrZHfNEDZz256ho3Q4gt7YrF2xApo5g.html
I enjoyed watching. i got two questions 1) how do particle entanglement experiment fit in quantum field theory? 2) the force (if icall it so) that caused the big bang could it be the same force causing the universe to accelerate (dark energy)..... since no breaks have been applied to counter it so far. thank u
Entanglement is a result of the integral and partition thingy that he didn't explain. :) From what I understand, the maths involved are easier to understand using quantum mechanics, however.
I don't like the idea of a moment in time( the idea of a beginning of the universe) were t=0 . In fact when i imagine o.oooo etc . and i put as many zeros behind as the number of quarks that are present in the universe , then i could still write a 1 after it . so in my opinion there is no time=0 . It is in fact an asymptote , it nears infinitely close to 0 but it will never become zero .
Wow, best so far. Heart of Britain
Very informative.
My question: how does general relativity (spacetime curve, etc.) fit in? Great lecture by the way!
he desceibed it as in the gravitational field...
Shot in the dark, very very theoretical but still a serious question. We only discovered the Higgs field four years ago. Its theorized that there are fields of 'spiritual' origin that we are currently unable to detect. Would you, David, hypothesize that the field nature of quantum mechanics leaves room for interpretation of these 'spiritual' aspects to the universe that we seem unable to prove with modern science?
Blue prints are prior to building ? Great talk ! Closer to reality !!
While the wave function is continuous, it seems unreasonable to conclude from it that nature itself is continuous when the physically meaningful solutions are discrete. It’s curious that more physical reality is assigned to the mathematical model than to the outcomes it predicts as making sense physically-especially when considering the paradoxes of infinite divisibility. It's like attributing physical existence to the Real line
A QUANTUM FIELD ISN'T LIKE A CLASSICAL MAGNETIC, ELECTRIC OR GRAVITIONAL FIELD.
A QUANTUM FIELD IS JUST A MATHEMATICAL TOOL USED TO DESCRIBE "REALITY".
Field + Dirac equation -> particles? Solving the Dirac equation gives the quantization? The quantization here is the number of particles.
Excellent Dave!!!
This is probably because of my lack of knowledge in the subject but it occurred to me that all the problems with finding a gravity field is that gravity is a just a feature of the material of space-time and that perhaps all the other fields are emergent from the material of space-time in the same way that all the known particles are emergent from the fields.
Miguel Rivera gravity is an incoherent dielectric field.
Miguel Rivera in that same sense if spacetime is the field of gravity then the other fields are other fabrics of other dimensions? ;)
Joking aside if space time is the field of gravity perhaps the graviton is the quanta of spacetime though that may also be from my lack of understanding
Firstly, the gravity field does exist, and they transfer speed of that field has been quantified. Recently I might add, and just a few days after the machines were turned on. What is harder to characterize is the structure or orientation of the field.
Why they assume gravity isn't just some 'feature' of stuff residing in space, has to do with photons. Photons react to gravitational distortions in space time, but not are not themselves manipulated by gravity because they have no mass. Meaning a photon (energy traveling at the speed of light) will travel at the speed of light forever. (By measuring billions years old light from far away stars). That's what the gravitational lensing shows. The photons wants to travel their course through space-time, but gravity, though it can't affect the photons, can affect space. This ability of some things to disobey gravity while other things must, implies a field with some associated characteristic that lets the field manipulate it.
If nothing obeyed gravity, we'd not be here; if everything obeyed gravity, the universe might exist, but would almost certainly appear different. Light itself would eventually slow, and get pulled into the nearest dense object, and the universe would look perpetually 'young' and our apparent horizon would be much smaller. Only few old stars, and close, filling up the sky.
It's the disharmony of field interactions that makes interesting things happen.
Nima Arkani Hamed says something like, Fields are ONLY a mathematical model - you can do field redefinitions, so they can't be fundamental. Geiger counters go blip, blip, blip not waaaeeeeaaaaeeee (detect particles, NOT waves). Schrodinger's equation does NOT explain what happens, only probabilities of what could happen in the future. It is about our ignorance, not about reality. That said, I've seen a couple of Professor Tong's QFT class videos, and he seems brilliant.
"Geiger counters go blip, blip, blip", I don't think that is related to how many particles it is detecting, if that was the case then it will do a continuous beep as there would be so many particles, even in an extremely low radiation area
great lectures and Q&A now quantum waves (gravitons) have been detected by LIGO from the big black holes crash, when is part 2 ??? :)
No, gravitons have not been detected.What was observed was classical gravitational waves. So, much like observing light, not photons.
Im agree with the first question...
awesome timing thanks!
My question :Is quantum fluctuation a fluctuation of energy? May the energy fluctuation cause the fluctuation of space-time curvature according to the Einstein field equation? The difference of curvature means the difference of gravity which seeds the formation of galaxies.
My question that I ask with the naivety, arrogance and stupidity of a child: could it be possible that the particles are granular but that the continuousness emerges from the quantum uncertainty aspect of the particle?
In other words, the particle is singular, however it's existance is distributed like a continuous field and this is what makes the "smoothness" of the fields..
Stupidity of a child? Childs always ask the right questions, I'm always impressed. But concerning your question (which isn't stupid at all):
There is neither granularity nor smoothness in the quantum world. In fact, there aren't even particles, that could be granular or smooth. That's disturbing, depressive, and spooky at the same time. Maybe you know from school, that light is as well a particle as a wave. You can do one experiment and prove, that it behaves like a water wave, and another, where it is made of lots and lots of bullets. The same thing goes for every kind of matter, let's say an electron. We can easily describe it as a particle, but you can also show, that it can interfer just as a wave. So when you enter the world of quantum mechanics, everything is described by the Schrödinger equation as a wave function.
Then you have this big Heisenberg uncertainty principle, which means, that you can't know a particles place and it's momentum at the same time. So once a (particle-)electron stops, it can't be granular anymore, and eitherway. Then, there comes the quantization. In Quantum Field Theory, we call it the second quantization, so the field itself is quantized. So bye bye, smooth field. Particles aren't more than peaks in this field, everything is entangled. It's not, that we look at a pointy object through a milky lense, it's just by nature a really weird object, that we'll never be able to imagine. Very impressive though, that in our macroscopic world, there is so much order and beauty.
+Marcel Hermes Stupid etymologically means amazed...hence, a child..
Then there is also string theory which is another thing itself right? lol..
+Marcel Hermes it's all info...
Good question, this was how it was thought of when Faraday first proposed the idea of a field. Maxwells equations (which come in part from Faraday), part of what they tell you is that an electric charge (e.g. an electron) will produce an electric field and moving electric charges produce magnetic fields. So in this context the field is emergent from the particle.
The particle stayed the fundamental constituent of nature until the late 1920s/1930s whereby Physicists started trying to form a theory that respects special relativity and quantum mechanics. The only way this was possible without running into contradictions was if you placed the field as the fundamental constituent of nature and the particle (the quanta of the field) being emergent.
Going back more towards your question, this was pondered by Richard Feynman: en.wikipedia.org/wiki/One-electron_universe.
Questioning the nature of Nature rather than questioning the nature of assumed matter gives a different perspective. Doesn't the emergence of discreteness from the continuous show the existence of both? Language including mathematics creates unnatural paradoxes reflecting dual aspects of natural phenomenon.
very good work
Excellent video!
thanks for the upload...........
Does the positron have a field of its own, or does it share the field with the electron?
That's the beauty of it: We have no idea
thanks for the video
Was hoping someone would ask if the standard model equation could explain the results of the double slit experiment.
Or maybe that's a stupid question, or I missed something.
You don't need as complex physics as the standard model to explain the double slit experiment. That experiment is much more insignificant than you think and is just a result of the statistical/wave properties of sub-atomic particles.
It's pretty clear that continuous is only an approximation of discrete.
You fill a bucket with sand. How much sand is in the bucket ?
You could count the grains, but it's easier to say "about two kilograms".
that's a pretty specific example, and i could just easily flip it on its head, and say that discretisation is an approximation of continuity. for example, think about how you talk about "where" something is. you could chop space up into small cubes and say that the object is in one of those cubes; but it's more fundamental to talk about where the object is on a continuum. perhaps space is quantised, but it wouldn't be in a strict sense like the above example.
@@bayleev7494 All good points. But the continuum is complicated -- a real number can contain an infinite amount of information.
Tesla understood the quantum gravity(though he wouldn't call it that), it's why he wrote Einstein a letter letting him know he was close but wrong.
Also, there is no graviton.. It's all about resistance and attraction, push and pull like magnetics, friction and culmination of forces, like he said at one point, collective behaviors.
Du Fung pressure mediation.
Fantastic talk!! I have a question on the age of the universe: how can we discuss of the absolute time passed after the big bang if we know that time is relative, and depends on the speed of the observer?
The average density of the cosmos is approximately constant so clocks tick at the same rate for everyone (approximately)
"Solving the equation is extremely difficult". I wonder if this will become easier once we have quantum computers because of their inherent continuous nature. Currently there are some commercial quantum computers that can solve very narrow optimazation problems in field equations.
Solving perturbation problems and numerical solutions to integrals are one of the main drivers behind making a Quantum computer.
Now Google has done it we will soon be seeing results
@@ramanunnikrishnan7354 multiple companies have done it. The question is how many qubits it has and how long they can stay in a quantum state and how stable they are. If you have to run every equation 1000000 times just to be able to "trust" the result, it might not be worth it :)
Does space hold the Universe apart, as it appears in the Field of Relativity OR does the space bind the Universe together, as it appears in the Quantum Field? Is this either A or B or is it both?
Brilliant
Judging by the way he was dressed and his overall demeanor, I was sure the guy at 4:48 was going to solve the equation.
I think i may of solved the equation with my comments on tgis video. 2 so far.
I'd like to hear as to why he is skeptic about quantum influence in biology.
i know right? tunneling is proving to be incredibly common in all sorts of organisms. although, i would guess he was playing it safe here? or maybe interpret that quantum effects can't be observed macroscopically? still strange, though
Physicists can you please correct me in thinking the quantum field fluctuations could be the consciousness of nature. Could this be or am I inventing a psuedo science that can be proven against.
Fascinating lecture and q & a thank you
Based on my little understanding, if you bring the concept of consciousness among these so-called fields, it will no longer belong to quantum theories, rather being discussed in the field of metaphysics and philosophy, i could be wrong, but this is how I think it will be :)
I think there is alternative approach to looking at space-time nature of universe, What if time is not even a factor in this whole scenario. We are observing the hypothesis as an observant who is evolved in to take the time as discrete measurement unit. There are many persons living who does not perceive the nature of time at all. If we take from their point of view nature of events is as it is; the state of matter changes, What if gravity/strong/weak force influence the matter state change (accelerate/accelerate) in its own sphere so that it seems different to observer outside. We should look into effect of forces on matter change in different way rather than putting time into factor.
With that computer simulation of "nothing". I'd like to know to size or volume of space being simulated.
Unfortunately the speaker's references to "this" when cursoring over various parts of the equation aren't clear because we cannot see in the provided video which portions of the projector screen his pointer is moving over.