Q&A – Quantum Fields: The Real Building Blocks of the Universe – with David Tong

45 thoughts on “Q&A – Quantum Fields: The Real Building Blocks of the Universe – with David Tong”

1. Not a word about quantum entanglements, which suggests non locality in time and space ?

2. Let me help all you physicists, "God said…"

3. 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.

4. There is evidence of discreetness underlying the universe: planck length and planck time.

5. My son understands "Quantum" much better than ???me???.

6. Discrete or Continuous? Continuous

7. If you are New Age, listen here – 10:00 . You probably won't understand this stuff about "Quantum Biology" but he is saying that it is all just a bunch of made up crap. And he should know.

8. Does anybody know who the M.C. is. I think I'm in love with that sweet voice ???

9. "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.

10. I don't understand how quantum fields are consistent with string theory. Aren't strings discreet things? Are they spread out in probability clouds, or do they have discreet locations?

11. Ugh, I hate it when theoretical physicists wade into topics they don’t understand, like biochemistry. Quantum effects in energy transduction and macromolecule structure have been well documented since the days of Linus Pauling.

12. Our big bang was the arising of a black hole in another universe. Since it eats stars and matter our universe expands even until today. We are living inside a black hole or in a singularity. Even from our universe new black holes arise creating new universes.
    Like a bucket filled with water, with holes in the bottom leaking into other buckets with holes in the bottom. And so on. The event horizons project their universes inwards. We are code on 2d surfaces.

13. If gravitons exist they must be associated to the field of gravity. This field is excited by bent spacetime or the presence of matter bending spacetime. The constant flow of gravitons from the gravity field towards matter creates somekind of a waterfall of gravitons. They 'collide' with matter particles giving them momentum. Therefor gravitons 'push' matter together. Since the field is undepletable gravity is a constant flow anywhere in the universe.

14. what about "time" ? is it a field of itself ?

15. 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.

16. 33

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

18. I am not a continuous wave I am quantized

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

20. This lectures are ignoring quantum gravity, which is not a field theory. That's why string theory was developed, and why field theory is so 20th century.

21. 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?

22. very good work

23. 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

24. Excellent video!

25. Is anything that comes out of NASA legit? 14:20

26. Seems a bit precocious to say they know what is happening some less than a billionth of a second after some supposed "big bang." I call BS on that.

27. 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!!

28. Thank you so much for this lecture. Great speaker.

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

30. 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?

31. 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.

32. David Tong is the greatest speaker. Just amazing.

33. What differentiate the fantasy from purely science? Let try to answer this question as to create the physical rules of science explanation and especially when because of the some reasons experimental proof is difficult. Such researches are astronomical ones for example. So how we have to examine theories in hard experimental proving environment? Simply answer is: as to observe the logic of likelihood of universe picture in accordance to the physical laws. It means that we cannot use any category which definition contradict to the known and proved many times physical laws, such as: ‘big bang”, “black holes”, “negative energy”, absolute or empty space, if we cannot proof their existence and more over if we cannot defined exactly what we searching for, then that is fantasy but not science! Obviously with such categories it is impossible to create likelihood of the universe picture, thus nobody can take this explanation seriously even the writers of novels as well. There is necessary to observe one more mathematical rules and that is the explanation to be only possible! G.Kanev

34. 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.

35. 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?

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

37. I am a chemistry I want to be your affiliate

38. Incredible! It is my conception that Opposite fields of Radioactivity; Everything from UV light weighing down on us, Forces us towards a constant source of Radiation emitting from Ocean floors and Uranium at its Cores. Varying Radiation levels due to whats at the block Cores of the Planets In Our solar System. We must Trust Gods instinct for giving us life and our solar system is the Building Block as a greater being. I love These things even If I don't understand them.

39. The Schrödinger equation is continuous, but it only describes a probability wave. Both probability and waves are emergent phenomena.

40. Why are people so confused about the 'Big Bang', and the fact that we cannot see back to that instant? It's really simple; when we look at the 'Cosmic Microwave Background' (CMB), or the limits of the observable universe (which might be the same thing), all we are doing is looking out to the event horizon of a black hole. We are inside it. As a result, as we view further and further outwards, things are seen which happened longer and longer ago. At that horizon, and from our viewpoint, time itself stops. It's an exponential (or similar) function, so we can never 'reach out' – or see back – to t=0.

    This allows for the concept of infinity, and also means that there is no need for 'something before' the Big Bang, and also means that there is no need for anything 'outside' our universe (reality, if you will), since the whole thing is likely recursive. In turn, this explains why our current theories and measurements begin to break down as we try to reach the 'Big Bang'.

    We see evidence for black holes within the universe. Supposing you could cross the event horizon of one, you wouldn't know that you have done so, until you looked 'backwards' (which would actually be in any direction), whereupon you would see a 'CMB', apparently at a huge distance (physically and temporally) away from you. I.e, you cannot go 'outside' it, and which looks no different to our present CMB.

    What this, in turn, means is that you could go from black hole to black hole, and still be in the same universe, each view of which appears to be infinitely large and old.

    Furthermore – and here I'm speculating somewhat – it might be equally impossible to actually arrive at a singularity within any black hole, since that singularity would only be one of many singularities, each of which appears to be nothing more than one of many black holes within the universe as you experience it. As said earlier, it's fully recursive. So-called theoretical 'multiverses' are actually only one universe. With all of this in mind, therefore, the name 'universe' is absolutely appropriate.

41. As buddha said you quontum behaviour cannot be understand physically which change very very very 100000000000000000000000000 fast and irregular where what you have to understand is there is nothing which exist any moment

42. Was the Big Bang not just a large-scale quantum fluctuation? Couldn't such a thing happen if given an infinite amount of time?

43. 6:37, Harry Potter has questions about QFT

44. Finally honesty.

45. Doctor Tong have you talked to any geneticists lately? Junk DNA. Crystalline silicon as a substitute for carbon based biological substrates. The Schumann Resonance changes and photonic data capacity. NASA is co-opted. Check your own DNA.

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