Quantum Fields: The Real Building Blocks of the Universe - with David Tong

The speaker introduces the talk about understanding what the fundamental building blocks of the universe are made of. He discusses how this question goes back thousands of years to the ancient Greeks, has been discussed many times in the past, and is still an important open question today that he will revisit.

The speaker traces the development of our scientific understanding of the fundamental building blocks of nature over history - from the periodic table of elements to the discoveries of the electron, nucleus, protons and neutrons, and finally quarks inside protons and neutrons. He explains that while quarks, electrons, and fields are currently our best theory, they may not actually be fundamental.

The speaker introduces the modern concept from quantum field theory that fields, fluid-like substances that fill space and can ripple/fluctuate, are more fundamental than particles. He explains how light and all particles come from excitations and quantization of underlying fields, using electric and magnetic fields as examples from Faraday and Maxwell's work.

The speaker discusses Michael Faraday's groundbreaking intuition and experimental work introducing the concept of electric and magnetic fields as invisible entities that fill space and mediate forces. This radical idea underlies all modern physics. Faraday speculated light itself is waves in the electromagnetic field.

The speaker digresses to discuss the immense mathematical difficulties and open problems in achieving a first-principles understanding of quantum field theories that describe reality. Some key successes and limitations are highlighted.

The speaker enumerates the 12 elementary quantum fields that make up all matter (electron, 2 quarks and neutrinos) and 4 force fields, which along with their interactions form the pinnacle theory of particle physics called the Standard Model. An example of its success is shown.

The speaker presents the full equation of the Standard Model, combining Einstein, Maxwell and others' contributions, that underlies all known phenomena and experimental results, while admitting much of it remains mysterious and there are hints of deeper unified theories.

The speaker discusses various astronomical observations, especially of cosmic microwave background radiation, that prove the existence of dark matter, dark energy and early universe inflation unexplained by the Standard Model, motivating searches for deeper physics.

The speaker recounts how despite beautiful theories predicting new phenomena, recent runs of the Large Hadron Collider have found no deviations from the Standard Model, defying expectations and leaving physicists puzzled about the way forward.

The speaker discusses three possible responses from theorists to the null LHC results - believing discovery is just around the corner, building a next bigger collider, and challenging current assumptions underlying models and seeking completely different ideas.

The speaker advocates for intensified focus on achieving deeper understanding of the Standard Model equation itself currently, as his preferred response. He is optimistic unexpected insights and progress can arise from questioning accepted conventions.