The Biggest Ideas in the Universe | Q&A 11 - Renormalization
ฝัง
- เผยแพร่เมื่อ 5 มิ.ย. 2020
- The Biggest Ideas in the Universe is a series of videos where I talk informally about some of the fundamental concepts that help us understand our natural world. Exceedingly casual, not overly polished, and meant for absolutely everybody.
This is the Q&A video associated with Idea #11, "Renormalization." Mostly it is me trying to say in slightly better ways what I tried to say in the original video. But we also talk a bit about whether virtual particles are real, and whether an effective field theory of gravity can really explain all the data.
My web page: www.preposterousuniverse.com/
My TH-cam channel: / seancarroll
Mindscape podcast: www.preposterousuniverse.com/p...
The Biggest Ideas playlist: • The Biggest Ideas in t...
Blog posts for the series: www.preposterousuniverse.com/b...
Background image: art.alphacoders.com/arts/view...
#science #physics #ideas #universe #learning #cosmology #philosophy #quantum #fields #effectivefieldtheory #renormalization - วิทยาศาสตร์และเทคโนโลยี
![[UNCUT] รัฐสั่งหยุดปล่อยคลื่น! แต่หยุดพลังปะทุ “น้องหญิง” ไม่ได้ I คนดังนั่งเคลียร์](http://i.ytimg.com/vi/RmQh47eIiV0/mqdefault.jpg)
"There will be black holes" - a happy addition to my growing list of Carrollisms! "But that's OK." "We can do better." "Sorry about that." Thanks for the great videos - and the new drinking game!
Black Holes are nearly always the pinnacle of my enjoyment with any science related conversation or investigation. Mainly because they push us to the extremes of our knolwedge and are the surest source to the path towards new physics.
Nice
My favorite is "Guess what?"
Is "I wrote a book about that..." in your list?
There seems a clear cut difference between forms and processes. Forms are static representations that may or may not be accurate representations of underlying reality and reality we might say is process more than form. Us human beings are designed to see forms rather than processes - processes are usually inferred by 'stacking' forms.
This may be off topic but it is a question :/ .. anyways what do you think of the ideas in "Lost in Math" by Sabine Hossenfelder
What's that private video just added in this playlist?
Sean, you should tease the next idea at the end of each video so that we can come prepared and excited with dreams and hopes.
Wow, very nice lecture! Mind is a bit blown. This is why I watch things like this. Most of the time, most of the things are things I know... but every so often someone phrases something just a _little bit different_ and creates an epiphany, and this video did that for me, specifically with regard to EFTs being able to describe different sets of fields. I'd never heard anyone state that quite so explicitly. Thank you!
I love you Sean Carroll! In a way, it is a testament to the power of field theory to be applicable in effective ways to so many things, more than it is a testament to the unity of nature. And yet this applicability is the reason why Eugene Wigner spoke of the unreasonable effectiveness of mathematics.
I look for an hour video from you every night. No matter the topic I enjoy your knowledge!
Another great Q&A video. Thank you Dr. Sean Carroll!
I’m taking my formal course in quantum mechanics this fall, your videos on the subject were a great overview of what I learned in modern physics this past semester. Thanks for the review Dr. Carroll!
I was one of the maybe many who asked how it was possible that fields interacted.
I did not phrase it properly, but with a bit of time to introspect I find that my confusion came from what I learned about the Maxwell Equations. It was more or less let to believe by my teacher that, as the electric and magnetic fields influence one another's strength, they were the same field.
The reason for the electric and magnetic fields being one might be more related to observer's independence issues, but now I get how fields interact. If everything is represented by a field,...yeah ok, you'll have somewhat translated equations to this new paradigm. (an electron [[field]] will influence the electic field.
And I guess that does not have to mean that all fields are the same underlying one.
Great videos. Thanks again.
This is so stimulating, my brain freaking loves it. Thanks!!
Thank you Dr. Carroll, I always had my intuition about how virtual particles could explain the proton/electron interaction of an atom, but making it a clear distinction (not necessarily better) from the quantum wave function help me in my understanding.
I don’t know anything about this, but I’m here because your voice is so soothing to me!! :) found you from Joe Rogan! ❤️ hope all is well!!!
Thank you, for guidance through those dualities.
10:00 entanglement, observing a particle, are virtual particles ‘real’, stories we tell ourselves, wavefunction static over time etc. I’m struggling to make heads or tails of it.
Why is the electron a static cloud when I am not looking at it? How do we know that? We get a picture of *an* electron jiggling around when we do observe it. What counts as observing it sufficiently enough to where the electron cloud WF looks like a jiggling electron? Do the electrons in a human body or a table become sufficiently entangled enough to look like a jiggling electron? Or are they unentangled so are electron clouds that interact without collapse?
13:00 How do Fields interact? You should try to motivate and answer this question yourself and see how good of a job you can do.
25:20 EFTs can have different ontologies. The tangent Sean goes on here, about describing particles in a box as a fluid, as an analogy to FTs, hits at the heart of one of my reoccurring questions. It seems like we ask our theories to be obtusely powerful, with mathematics to reflect that, while also not demanding that the theory be applicable to domains analogous to single particles in a box. WTF is going on here?!?! Why demand obtuse power in some aspects of your theory whilst submitting that it fails with gravity, or EM, relativity, or something (subjectively) relatively simple? Skipping to 31:30 for UV complete QCD theory if it weren’t for gravity and Electromagnitism
30:30 the ‘level’ of QCD
And after that, the EFT for Gravity being a different language for GR that is specifically restrained and has the same predictions as GR, but with a more limited domain of applicability (because EFTs)
Great series of videos. This one kind of answers a nagging question I've always had about why physicists refer to gravity sometimes as a field and sometimes in terms of a distortion of spacetime. Catching up after doing a degree in Physics nearly 40 years ago :-)
Regarding "how do fields interact?", isn't it more intuitive to say that they are coupled in various ways such that their values pull on each other as if physically connected, e.g. by a spring or something? That's a much better answer, but I don't know that it's true =/
Hi Sean! Love all your videos! Ive just got one question in regards to entanglement...is it possible for entangled particles to be in different time periods (one in the past and one in the future) since the distance between them can be eg: between 2 galaxies or further , and time dilation comes into play. Thanks!
Loving this series. I've learned a lot. I have wondered for a long time how it is that a field of virtual photons can mediate both repulsion between two electrons and attraction between an electron and positron. What are the photons doing differently?
Thanks
Great content. Titles should start with the subject.
I love your videos.
We really need a better term than electron-ness. Any ideas?
Well I used to think I understood virtual particles. I don’t anymore.
Can virtual particle be of any different configuration than any known or would be known particle in standard model?
Tell it Sean!!!
Great explanation around minute 10 to 11:00
I wouldn’t name it ‘virtual particles!’ Maybe ‘transitional wave state!’ But if they named it that way, we have a bigger problem! Namely, what is wave and who is particle? What is the line between them to be described? More importantly, wave on what? All these questions would be irrelevant if we thought of matter as only a distortion of space itself!
When are physicists going to own up to the fact that the letters in the Latin and Greek alphabet are used up and introduce runes, Japanese hiragana and katakana, etc. to new stuff?
Haha
Don't give them ideas. Kanji are hard af.
At least you wouldn't get out of kanji so soon
But man, imagine having to learn advanced math and kanji at the same time
Meanwhile in math: *a l e p h*
Hi doctor Sean! I'm speechless about how grateful I am for your videos! I am a psychologist and I study quantum mechanics as a hobbie and I never hoped to understand as deeply as I am understanding this topics! It's simply amazing!
Do you think in the future we will have "flat spacetime" society, like we have the flat earth society? Hehehehehehe! Just kidding! Again, really, really thanks a lot!
At the moment all evidence point that the Universe its flat . The society gonna be for a curved one ....
Question: Since the positron is the anti-particle of the electron, is there a corresponding property in their quantum fields? The positron field and electron field overlap in spacetime, do non-particle vibrations in these fields somehow synchronize and/or annihilate each other?
"Non-particle vibrations" are not a real thing. Every mode of every wave function is a potential observation of a particle.
I'm not totally sure, but I believe the electron and positron are in the same field. A positron has the opposite phase relation to an electron, such that its wavefunction is psi* of a corresponding electron. Sometimes I've seen them write them as separate components of a vector field, too.
Do virtual particles sleep and dream (at night)?
Is Time and Entropy connected / the same thing ?
I guess we can say that the fields interact, terms like e-(x)e+(x)gamma(x) appear in the Lagrangian for the field interactions, and we can experimentally measure the magnitudes for each of the terms, so that’s how we describe the field interactions.
But I think what we lack is a way to derive the magnitudes from first principles. We don’t know why the magnitudes are what they are. It’s as if there are a bunch of knobs that set the interaction strengths for sets of fields that interact in our universe, and we don’t know why the knobs are set to those values.
This situation is a bit unsatisfying. Things are the way they are because that’s the way they are. It would be more satisfying if the knobs could be shown to have only one unique set of values.
Isn't the magnitude what's coming at us, into us, and through us all the time? It'll probably be pointed out someday that the Higgs field is actually our little slice of heaven, it's the 3d line we lay on, and all other fields displace it, and we measure the displacement as particles at different angles(spin). What Sean is showing me is what the wave intersection might be doing any of these infinite number of motions to equal what we see in Data. The data is momentary, not un-useful but hardly a slice of what is here. We're trying to guess the whole picture by looking at single pixels (now I know I'm in a simulation, thanks THC)
Dr. Carroll, if I understand it correctly, when a photon is redshifted (blueshifted) it loses (gains) energy ([EDITED]: proportionally to its wavelength change, since E = hν).
Where this energy is transferred to/from ([EDITED]: and how)?
How about...If energy is a wave in a field then it is transferred to another part of 'The wave function of the universe', just like a water wave in the ocean. If the ocean was in a container then the container would expand, just like the universe does.
@Astute Cingulus What are the particles that carry the energy?
A photon is an electromagnetic wave. Self propagating. The wave IS the energy. It only appears as a particle when we measure it.
If you could only write QFT book at some introductory level like your GR "Spacetime and Geometry" book... IMO there is still lacking a good clear introduction to the QFT accessible to amateurs and B.Sc. level students.
14:50 It would be cool if we could have a 'prism' to do this in reality.
Sounds like there's just one field capable of many different presentations
This is the most infuriating answer to the question “Are virtual particles real?” Because there’s a real question here. If I said there is an angel pushing around the virtual particles, you might ask: Is the angel real? The answer “well it’s a superposition over many states of the angel” dodges the question. Angels have angel-like properties. Can those be observed?
Also: This is dynamical but the wave function is not dynamical. This is also silliness. That’s like taking a block model of space-time and saying “if you zoom out, there’s no dynamics.”
If I am given a superposition over quantum states, then I can imagine a physical system being in each of those states. Here it’s not the case. So what’s really be asked is: Why is there a superposition over non-physical things and how does one make sense of that? (Non-physical because mass-energy is not conserved by the virtual particles.)
Great articulation
One thing that sets humans apart from all other animals is we tell stories. Stories are powerful, the words on the page and the symbols in the equations are meaningful things. The more they correspond with reality the more powerful they are. Still they are not what is real, the wave function of the universe isn't what is real, the universe is, the wave function is powerful because of it's correspondence with reality. It is a mistake to confuse the story with what it is about.
If the sun's gravity increased or decreased, what effect would be on the earth's velocity?
I think an increase in mass would increase the warp in space-time and we would reach a higher velocity. Depending on the amount of acceleration(mass added), we could escape to infinity or fall inexorably towards the center of mass. We may be lucky enough to fall into a different "stable orbit" but all orbits will decay eventually.
@@mwaringmlw Thank you sir!
Why fields vibrate?
Why wouldn't they vibrate? Similar to Sean's explanation of what IS a field, what ARE interactions, the current best description says that the field vibrates. We can imagine this in our macroscopic world with vibrating violin strings and any other analogy you care to examine, but in the end this is what our best mathematical description of reality tells us. People spend entire careers asking _but what does it_ really _mean?_ And to that, all I can say is maybe one day we'll find out.
You misss Sean's explanation from previos videos I think .
Quantum fields vibrate because are modes of the Wave function of the Un iv e r s e.
Is ontology english?
Welcome to math and science, where terms that mean nothing to 99% of the population have so much meaning it could take an hour to describe the basics of that single idea.
No black holes ...now
make the background even darker
Virtual particles = fatal attraction..
SC: "They are not arrows of movement!"
Also, SC: "Think of the positron as going backwards in time."
So, fields is a mathematical abstraction, correct ? they are not real!!!!
try to realize the truth there is no spoon
Do you think that's air you're breathing?
Damn. 399 😣
I'm sorry it's 2am and I don't understand all of this at the moment...maybe that's why I didn't finish college haha 😅
You speak too fast, please speak more slowly, thank you so much 🙏
Set your playback speed to 0.75 or below.
If he spoke any slower the video would just take that much longer. If I find a certain area to be so dense with information, I will often pause and ponder, replay thatsection, think about it some more until this new information makes at least some sense with everything else I think I know and then, _and only then,_ do I continue on the video.
And don't forgot that I do this often even tho I've spent years ingesting all of the information I can, short of an actual college course (which I really want to do, but would take a lot of time which I don't really have right now).
I think PBS Spacetime is 10x worse about this than Sean is, and that's why I'm happily sitting through 1h+ long videos. The whole thing about Spacetime is that most of the viewers understand nothing that he's saying, and he just sounds really cool saying all these mathy and sceincy things. I actually do try and understand what he's talking about, but it can be much harder specifically because he doesn't show the math because PBS Spacetime is not meant to actually teach you anything, it's meant just to show you some crazy result or some interpretation that has arisen through other people doing the rigorous math and putting in the countless hours of effort to _actually_ understand these things.
Don't get me wrong here, PBS Spacetime is one of, if not my most, favorite channel on TH-cam, and Matt is brilliant for making it even half understable without the maths involved, but it's still just entertainment, not education.
@@kindlin Im curios if you went to the University ! If the answer its yes, probably you think the same regarding your teachers from the Uni. What Matt does is educate you in the way an university teacher would do it ( at least in my country does ) . Its up to you to go deeper, to study ...library , boocks etc . You think that giving you a few equations will help you have a SOLID knowledge on the subject ? Nope ....It depends of whats good enough for you I guess .....I know for a fact that a budy of mine its having the same reactions to Sean's videos , as you have for PBS. Those equations and and explanations are to noobie for him .
Its like Feynman said when it was asked : Why magnets ? It depends what's good enough for you, what level you want to be the explanation : highschool, entry student , University student , etc .