I discuss a variety of topics in both the natural and social sciences, exploring the many fascinating insights that the scientific method yields about the world around us.
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An introduction to the particles and forces that constitute the standard model of particle physics. After some historical background, we introduce each of the three fundamental forces that comprise the standard model - electromagnetism, the strong nuclear force, and the weak nuclear force. We then compare and contrast the different types of particles these forces interact with, including the…
Beginning with primitive Cynodonts in the late Permian, we our evolutionary development through Mesozoic mammaliaforms, the divergence of monotremes from marsupials and placentals, and culiminating in the emergence of primates in the early Cenozoic. Along the way we discuss the emergence of important traits such as the mammalian ear and various primate adaptations for arboreal life. We then…
A survey of extinct animal species from the Permian through the Cretaceous periods. We discuss important differences between anapsids, synapsids, and diapsids, and then review diverse species from all groups, including pelycosaurs, therapsids, parareptiles, euryapsids, pterosaurs, pseudosuchia, and dinosaurs. We also consider aspects including bipedal gait, endothermy, gigantism, and the cause of…
A journey through the evolutionary history of animals, beginning with the split of the metazoans from protists about 760 million years ago and ending with the rise of the amniotes about 340 million years ago. The focus is the development of key morphological traits necessary for more complex animal forms, including the origin of true tissues, bilaterial symmetry, the complete gut, the coelom,…
Continuing from quantum electrodynamics part 1, here we explore the mathematical machinery used to compute interactions between particles, including propagators, Feynman diagrams, cross sections. We then walk through a simple example calculation to illustrate how these tools are applied. I conclude with an introduction to the problem of divergent loop integrals and how these can be resolved using…
A detailed look into the physics and mathematics of quantum electrodynamics, the theory of how light and matter interact. We discuss the generalisation of the Schrodinger equation to the Klein-Gordon and Dirac equations, and howw these describe the propogation of light and fermions respectively. We then consider the process of computing transition probabilities between quantum states, including…
A survey of the Earth's history through the lens of the geologic timescale. We begin with a discussion of the terminology of geochronologic units and how they are specified using 'golden spikes'. We then review the development of Earth's atmosphere, geosphere, and biosphere through the Hadean, Archean, Proterozoic, and Phanerozoic eons. We cover many topics including the supercontinent cycle, the…
An introduction to the techniques used to study the history and ages of geological speciments. We begin with an overview of chronostratigraphy, covering principles of relative dating, way up indicators, and biostratigraphy. We then discuss geochronology, including a review of early attempts to determine the age of the Earth, the principles and assumptions of radiometric dating, and the…
An introduction to the process of development, beginning with fertilisation and covering the stages of blastocyst formation, implantation into the uterus, gastrulation and its constituent cell movements, neurulation and the role of the notochord, and the beginnings of organogenesis. We also discuss the differences in gastrulation between protostomes and deuterostomes, along with the many…
An overview of Magnetic Resonance Imaging (MRI), beginning from the basic physics of nuclear magnetic resonance, and covering the use of radiowaves to excite nuclear spin states, and the T1 and T2 modes of relaxation. We then explore how these phenomena are used to produce 3d images, including magnetic field gradients, frequency encoding, phase encoding, and Fourier transforms. We conclude with a…
