The Biggest Ideas in the Universe | 11. Renormalization

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 Idea #11, "Renormalization." When you include particles in Feynman diagrams of all possible energies, you often run into infinite results, which are clearly wrong. The modern approach to this problem is to work with "Effective Field Theories," in which we admit that we only understand physics up to some cutoff energy scale. While enormously successful, this EFT paradigm also runs into issues with the Higgs mass and the cosmological constant.

#science #physics #ideas #universe #learning #cosmology #philosophy #quantum #fields #effectivefieldtheory #renormalization

[calwerz]

Poor Sean, wanted to keep the episodes short, but they are just getting longer and longer. :) I'm not complaining tho.

[sth]

With all of the ugliness going on in the world right now, these videos remind me of how incredible humanity can be at our best. Thank you very much Prof Carroll.

[captainzappbrannagan]

This is the best explanation i have ever seen on why infinities occur, why they aren't real, and how we correct for them without skewing results. Keep the great vids coming!

[gausedukativnicentar]

I am a theoretical physicist, working in the field of quantum gravitation, and I can say that this is the most straightforward explanation of the concept of renormalization compared to a lot of actual physicist books. You got yourself a new subscriber, Sean!

[kjrunia]

3:30 Sean Carroll is the Bob Ross of painting lush quantum fields with little trees with branches coming out.

[silent_traveller]

I am really enjoying how deep we are going here, keep doing Dr.Sean!

[themenace]

I have an exam tomorrow, but who cares? Sean Carroll posted a new awesome video! :-)

[dude]

This has very quickly become my favourite series on youtube, thank you for the in-depth explanations Sean.

[atanumaulik]

Hundreds of thousands of people learning about renormalization in QFT. Astonishing! There is hope for mankind.

[pamelacollins]

Absolutely fascinating and enlightening. This is the first time I’ve heard the problematical infinities explained. Thank you!!

[viewer]

I hope there are some young Einsteins watching and learning from these and what Brian Greene is doing !

[DrJeeps]

As a (semi-retired) Canadian professor of psychology, apart from my own field of social psychology, one of my passions is physics. During this pandemic lock down I am thrilled to be able to watch YouTube videos from some of my favourite physicists including Sean Carroll, Brian Greene, and Lawrence Krauss. What a shame it will be when these videos come to an end. The promotion of the physical, biological, and social sciences in society is a must when certain populations, especially in the United States, appear to be turning away from science and filling their knowledge void with religion and superstition. Humanity needs a greater knowledge and understanding of science, not superstitious nonsense.

[rc]

Dr. Sean Carroll, in the Q&A would you spend some time on the “quantum foam” of the vacuum? I understand that Feynman virtual particles are placeholders for the complicated back-reactions of the fundamental fields. But what about these foamy short-lived particles at the ground state? Thank you.

[esperancaemisterio]

Stopping everything and starting to watch, as usual! Thanks Sean!

[picksalot]

Renormalization has become my favorite topic in this series of lectures, and Ken Wilson is a hero. I'm so glad that he figured out how to get rid of all those "infinities." There is a point when concepts exceed available experiments, and it becomes a necessity to have a precise language to communicate coherently. Thanks

[forbdonutyt]

A welcome break from everything going on right now. Thank you!!

[adhdasian]

Interactions was a doozy, Normalization was no less! ty Sean for getting us through :)

[faisalsheikh]

Sean Carroll and Brian greene sir my role model sean sir lot's of love from india

[iziskin]

Definitely the best public explanation of renornalization that I have ever seen. AND he even justified it by citing the fact that when we renormalize we implicitly accept that we are just writing an EFFECTIVE field theory that approximates some deeper theory that describes interactions at energies above the cutoff (e.g. maybe String Theory, but probably not)
Beautiful!!

[jeanenry]

The cut-off idea came out with Debye's Specific heat theory, only wavelengths of interatomic distances were included, circa 1905. More rip-off!!