For some time now I’ve been trying to develop a good explanation of my research to the general public. The current work-in-progress is composed of six ‘acts’ with increasing specificity. I’d like to present these over my next three posts.
Act 1: Science
Science is a branch of human knowledge associated with the rational, objective, and empirical study of the natural world. The primary mode of generating such knowledge is the scientific method, by which ideas are checked against experiments. Science differs from the humanities in its subject and from the arts in its method.
Scientific fact is based on observation. Causal explanations for these observations are theories that must be rigorously checked against experiment. It is worth highlighting that a “theory,” in the scientific sense, both explains observed phenomena and predicts further observable phenomena. In this way scientific theories are falsifiable and differ from the common use of the word “theory” that implies opinion of speculation. A theory may end up being incorrect when subjected to further experiments, but this is a feature rather than a shortcoming of the scientific method.
Act 2: Physics
Physics is the branch of science concerned the fundamental laws of nature. Branches of physics study atoms (and all things subatomic), materials in different phases (condensed matter), dynamics of different systems (e.g. geophysics, general relativity), outer space (astrophysics and cosmology), and applications to other sciences (biophysics, physical chemistry). In some sense physics is the “purest” science in that it is an interface between fundamental models of nature and experiments.
Unlike the other sciences, physicists can roughly be divided into theorists and experimentalists. Theorists are primarily concerned with mathematical models of nature that can be used to explain experimental data. Experimentalists are primarily concerned with testing theories and acquiring new data that may point to science beyond current theories. This divide occurs because of the high degree of specialization required to study nature at the level of physics. Theorists must be fluent in advanced mathematical methods while experimentalists must be clever to build apparati and interpret data.
Act 3: Particle (‘High Energy’) Physics
Particle physics is the branch of physics concerned the smallest building blocks of nature. In the past century, the “particles” that physicists considered “smallest” have gone from atoms, to nuclei, to protons, to quarks (not to mention electrons and their cousins). We have also learned how to think of the fundamental forces of nature in terms of force-mediating particles such as the photon.
Why do we study these particles? One reason is that we hope that by studying the basic building blocks of the universe we can understand composite objects better (reductionism). There is also a philosophical/aesthetic appeal associated in understanding what the ultimate basic building blocks of the universe should look like.
The current canon of particle physics is called “The Standard Model” and was mostly completed in the 1970s. It is a kind of quantum field theory called a non-abelian gauge theory (this means it is based on certain kinds of symmetries) and explains the strong and weak nuclear forces as well as electromagnetism. It has passed every experimental test (up to some recent modifications in the neutrino sector) with flying colors and is regarded as a stunning success.
Next time: stay tuned for Part 2, where I discuss what is meant by an “effective theory.”
