don't believe ever watched a video where the presenter was so conversant and approachable in such an exotic subject.

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.

Excellent lecture and Q & A session. I look forward to more lectures by Professor David Tong.

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

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!

The humility of the lecturer is really something to behold

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.

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.

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!

David Tong is a good Speaker! Must appriciate his knowledge and confidence to explain such a complex topic...

I wish this Q/A session never end ...Excellent Q/A session by Dr.David Tong.

"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!!

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!

What a wonderful speaker and topic. I love his style: friendly, direct, informed, but taking no prisoners :).

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.

I have found a new favorite physicist. This is a good day

Thanks for publishing this most enjoyable talk!

Thank you so much for this lecture. Great speaker.

Great talk and presenter!

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!

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

Thanks for the engaging discussion.

I feel very lucky for getting to this video. Delicious stuff!

This guy is on top of his game!

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.

i think i found this as the best lecture on quantum fields

awesome timing thanks!

This is even better than the lecture!!

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?

thanks for the upload...........

Excellent Dave!!!

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.

thanks for the video

Very informative.

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.

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?

Sire David Tong simply too class my favourite Professor!

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?

Excellent video!

6:37, Harry Potter has questions about QFT

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 .. 👏👏

He's possibly the best science presenter.

Wow, best so far. Heart of Britain

Excellent, my perception just went up up. David Tong is my new favourite science communicator. I wonder if he has a brother called Pete?

very good work

Finally honesty.

Long Answer; Yes with an 'if' Short Answer; No with a 'but'

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 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.

09:30 "Is there anyone up in the Gods have a question?" that sounded funny. 'Yes!', said God. he he

Brilliant

Blue prints are prior to building ? Great talk ! Closer to reality !!

There must be a noble prize give to that person who will solve that exponential terms including integration and other terms of that equation..

The equation has i sqrt(-g). Is there any reason that this is not simplified?

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?

You are one of the best i have ever heard. No match to your talk.

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

I'm dying to see one these live. Maybe vacation 2020

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?

Wishing happy Christmas to all of you question and answer session I like the your theory of quantum field theory and it's relation with sir Albert Einstein theory of general relativity theory of quantum gravity ❤️🙏❤️ sir 👏👏👏👏👏 thank you so much to learn exciting intresting theory

With all the mass in the universe together. Would nt the universe be a massive black holes? Or would all matter become hyper compressed raw energy?

great lectures and Q&A now quantum waves (gravitons) have been detected by LIGO from the big black holes crash, when is part 2 ??? :)

Does the positron have a field of its own, or does it share the field with the electron?

I am wondering. All this equation withholds is just explaning these fields theories and all those things. But how is it than that when I burn my vinger the burn moves with me? In other words what makes history of a chemical reaction stay with me and not leave me into the universe (spacetime)?

are you familiar with a energy or power of G OD ?

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.

Is the motion in the quantum field (inflation) has correlation with fractals? Madelbrot geometry?

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.

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!!

Is there something which interconnect all the fields???

When two or more fields come together, why do the result also describable by a field? Why does a cloud of Rb87 atoms form a Bose-Einstein condensate?

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.

What does 10 to minus 33 sec mean in a quantum realm that is near the singularity?

Answer to the first question, he refuses to accept granular reductionism. A man after my own heart!

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.

The beak on the first guy is award winning

Sir i wanna ask that what is the basic knowledge or topics we need to understand, to understand the components of that equation

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.

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 question: how does general relativity (spacetime curve, etc.) fit in? Great lecture by the way!

So is human level consciousness a Quantum Field? This would allow for ESP phenomenon like remote viewing, intuition, the ability to predict. Technical Intuition and New Thinking Allowed's UKposts channel has more information on remote viewing. Dr. Peter Fenwick neuropsychiatrist extrodinaire might be interested in your research.

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.

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 .

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.

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.

Im agree with the first question...

With that computer simulation of "nothing". I'd like to know to size or volume of space being simulated.

Field + Dirac equation -> particles? Solving the Dirac equation gives the quantization? The quantization here is the number of particles.

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.

Who's the kid with the glasses who always asks questions?

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

It seems like the universe emerges from the vacuum. That moment would be a beginning. What if the vacuum is the continuum of being? What if the nature of Absolute Reality is to function/serve as a diversified unity (continuum of being) that actualizes as a unified diversity or Uni - verse?

What is the computer simulation of the fields describe? Is it matter popping in and out of existence?

I'd like to see more physicists talk about entanglement and Juan Maldacena's work.

Interesting

As it is now accepted amongst quantin theorists that the universe is made up of waves is there a way of measuring either the viscocity or friction between the waves. Although i say waves i believe the consencus of opinion is a combination of newtons law ie particle physics and quantum mechanics ie wave theory.

"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.