QCD: Quantum Chromodynamics

The strongest force in the universe is the strong nuclear force and it governs the behavior of quarks and gluons inside protons and neutrons.  The name of the theory that governs this force is quantum chromodynamics, or QCD.  In this video, Fermilab’s Dr. Don Lincoln explains the intricacies of this dominant component of the Standard Model.

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[alphadawg]

This guy is amazing, in every single one of his videos. He can explain the most complex thing in a way a 4th grader could understand! I admire his genius!!!💡

[professordanfurmanek]

One of the most masterful physics professors on planet Earth!! You truly set the bar for all other professors!!!

[alexandrugheorghe]

I propose to have a playlist strictly dedicated to Dr. Don on this channel.

[otakuribo]

Up and down, from top to bottom, I think you're charming and strange.

[spencerm]

after watching this, I watched like 6 hours of worth of lectures that talk some/were about qcd. the Fermilab channel is definitely up there with all of the Brady Haran channels in my book. Can I just have all of Dr Don's shirts?

[derdagian]

No concept is difficult when Doc Lincoln explains it, and you shouldn’t be afraid, when he’s relaxed. You relax, and eat it.

[evilcam]

Whoo hoo, you are finally getting into QCD.

I hope you can go more into depth with QCD at some point. In order to explain some of the points regarding asymptotic freedom, and how weird it is (you touched on it in this vid, but I would like it if you went more in depth, in some future video) creating mesons with the excess gluon energy so it is absolutely impossible to ever see a single quark.

Likewise, that the Strong Nucelar Force is just a tiny bit of left over force leaking out of the quark-gluon interaction. It really blew my mind, and continues to do so, knowing we only exist because the gluon field is so strong that tiny bits that leak out of it are what holds nucleons together. That the tiny bit of excess energy leaking out of the system is so strong, that it remains the strongest force in the universe, even though it is basically just race amounts getting out due to confinement.

[pixxelwizzard]

Really enjoying these videos. Fermilab has done a fantastic job with them. Thank you!

[PurpleChevron]

You do an outstanding job of bringing complex physics to the lay person and I love watching your channel.

[andrehorbach]

One of the best videos about physics I have found on Youtube. Thanks and congratulations.

[physicsphilosophy]

Feels bad people have enough time to waste upon watching worthless videos and ignoring these amazing videos of reality of our world. Great work sir by the way. I'm so pleased to watch ur videos 😊😊😊

[kjlee]

Thank you for clear explanation. By the way, I suppose that the term "Quantum Chromo-Dynamics" is like that of 3 linguistic fun. Namely, the 'Quantum' derives from Latin, 'Chromo' from Greek and 'Dynamics' is English in itself. Eventually the usage of these 3 sorts of languages is the same idea of 3 sorts of coloristic tiny particles in the mother bowl, I perceive. Very ingenious and reasonable usage. Yes, that's the same term as 3 characteristic languages vs particles. So be happy !

[akumar]

I have limited formal sceince education, I enjoy watching these videos, one has to marvel at the sheer brilliance of the human mind .

[stephenzhao]

Thanks a lot. 👍 I do appreciate it! 3:06 In any event, unlike electric charge, which comes in two varieties: plus and minus, the strong charge comes in three varieties, named red, blue and green, anain, nothing to do with regular color. The particles that the colored quarks exchange are not photons, but rather particles called gluons. The photon is the particle of electromagnetic force and the gluon is the particle of the strong force. And, in analogy with QED or quantum ELECTROdynamics, we call this theory QCD for quantum CHROMOdynamics. Get it? Chromo? Color? Alright, sometimes I'm a little embarrassed by my tribe. For those of you who are fans of Feynman diagrams, we draw an exchanged photon as a wavy line, while a gluon is a corkscrew. And, just like all Feynman diagram, the Feynman diagram of two quarks exchanging a gluon orresponds to an equation that a sufficiently diligent stuend can solve. ... So how is QCD different from QED? Both involved exchanging force carrying particles between other particles carrying charge. The photon is massless. The gluon is massless. The photon has no electric charge. The gluon has no- oh wait a minute ... there's a difference. Gluons carry the strong charge. They have color. And that little different has a huge consequence. 4:28 5:42 But here's the tricy thing. When we break it, the energy that was stored in the string converts into matter and antimatter, specifically quarks and antiquarks. This process can go on for a while with more stretching and breaking and creating quarks and antiquark pairs. In the end, the particles all pairs up and what we get is a bunck of particles all travelling more or less in the same direction as the quark that got knocked out of the nucleon. Physicists call this blast of particles a jet. 6:09 And we see jets all the time. Here is a picture of a real even collision in the CMS detector, 6:12 one of the big LHC experiments. See those sprays of particles? Those are jets. So those are the big ideas of quantum chromodynamics. The strong force has a different charge and force carrying particle than quantum electrodynamics, but, in some respects, theay aren't so incredibly different. The big difference is the fact that the force carrying particles is itself charged with, as we have seen, dramatic consequences. The subatomic realm is really a pretty crazy place. 👍

[nutCaseBUTTERFLY]

This video is really awesome! Keep posting more in depth stuff like this.

[AllenKey]

I had a choice between PBS Spacetime and Fermilab to hear this coverage. I just love how this guy speaks

[namamigohain]

Thanks Dr. Don for explaining the QED … u can make physics a piece of cake to any layman…

[AaronKuoeatvoltage]

okay, I'm gonna ask the million dollar question on everyone's mind.





WHERE DOES DR. LINCOLM GET HIS AWESOME

[tgo]

always impressive. thank you, fermilab. 감사합니다.

[johnbartucci]

Where were you when I was an undergrad physicist?! Makes more sense than my Nobel laureate profs ever made!