The world around us is made of atoms. Did you ever wonder where these atoms came from? How were the gold in our jewelry, the carbon in our bodies, and the iron in our cars made? In this lecture, we will trace the origin of a gold atom from the Big Bang to the present day, and beyond. You will learn how the elements were forged in the nuclear furnaces inside stars, and how, when they die, these massive stars spread the elements into space. You will learn about the origin of the building blocks of matter in the Big Bang, and we will speculate on the future of the atoms around us today.
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Physics of the HIGGS Mechanism and Particle Mass – Part 1 (of 6)
This video (the first in a series of six) gives an introduction to “Fields and Particles” and to some ideas relating to the Standard Model of Physics. The families of fermions and bosons are discussed, and how the latter relates to the forces in Standard Model via color charge, electric charge, and the weak charge. The masses of bosons are given, and compared to the predictions of the Standard Model (zero mass), giving rise to the need for some ‘extra’ explanation. All this is in preparation for the remaining videos in this series which aim to ‘explain’ how the various particles of the Standard Model obtain their mass.
In this video (Part 2 of 6), a simplified outline of the Lagrangian Method is discussed, and the suggestion made that it might later be applied to, and help us to understand, Quantum Fields. Scalar, Vector and Dirac fields are considered – along with field oscillations and the mass of any quantum excitation. There is a brief mention of Gauge Invariance. This, along with an earlier video (Part 1), is in preparation for the remaining videos in this series which aim to ‘explain’ how the various particles of the Standard Model obtain their mass.
This video (Part 3 of 6) deals with the application of the Lagrangian Method (discussed in Part 2) to Fields and, in particular, to a ‘Real’ Scalar Field. There is further discussion of field oscillations and particles, gauge invariance and the fact that the Standard Model predicts the mass of bosons to be zero. This, along with earlier videos (Parts 1 and 2), is in preparation for the remaining videos in this series which aim to ‘explain’ how the various particles of the Standard Model obtain their mass.
This video (Part 4 of 6) looks in a little more detail at the Lagrangian of a ‘Real’ Scalar Field, and in particular, takes the case with the ‘imaginary’ mass term. This leads to a discussion of Spontaneous Symmetry Breaking, the Residual Higgs Field, and the oscillation of the field with real mass. It moves on to consider the Lagrangian of a ‘Complex’ Scalar Field, again with Spontaneous Symmetry Breaking, the Residual Higgs Field, oscillation with real mass BUT this time including a new ‘particle’ – a “Goldstone Boson”. This, along with earlier videos (Parts 1, 2 and 3), is in preparation for the remaining videos in this series which aim to ‘explain’ how the various particles of the Standard Model obtain their mass.
This video (Part 5 of 6) builds on the previous 4, and considers the Complex Doublet Scalar Field (Higgs Field) which, with Spontaneous Symmetry Breaking, produces not only the residual Higgs Field and an oscillation with real mass but also THREE Goldstone bosons. The differences between massive and massless particles are discussed in a little more detail (energy and degrees of freedom), and there is a qualitative discussion about how the three Goldstone bosons can give mass to some gauge bosons (W and Z). A mathematical ‘illustration’ is given of this process. This, along with earlier videos (Parts 1, 2, 3 and 4), leads on to the final video in this series (Part 6) which aims to ‘explain’ how the fermions of the Standard Model obtain their mass.
This final video (Part 6 of 6) builds on the previous 5 and considers how the presence of the residual Higgs Field might give mass to the fermions. It discusses left-handed fermions and the weak force, and the reason why (according to the Standard Model) fermion mass should be zero. Simple aspects of the Yukawa potential are introduced in order to ‘explain’ how a fermion traveling through the Higgs Field gains mass. Finally, and very briefly, various coupling constants are considered, along with the discovery of the Higgs boson in 2012.
Speaker: Dr. Edward Murphy, University of Virginia Date: November 13, 2012
