Physics for physicians.

During the first years of the twentieth century, the core subject in preclinical medical education was anatomy. Will that still be the case in the first part of the next century? The answer could lie in the experiments at the Large Hadron Collider where the nature of matter is being studied. Wave-particle duality, atomic and molecular interactions will perhaps illuminate previously unexplained elements of human biochemistry, physiology and pathology. The use of physics in diagnostic medicine is increasing. The benefits of X-rays in diagnostics have been appreciated for over a century, and other modalities of electromagnetic force, e.g. ultrasound and Magnetic Resonance Imaging (MRI), are extending the diagnostic range and accuracy. It might be that increasing understanding of physics could similarly lead to the development of future diagnostic tools using not the stethoscope but a hand-held device employing these modalities. The future of physics was defined by the Consensus Theory of particle physics, which went beyond the atom as the basis of chemicals but predicted the existence of subatomic particles. The standard model states that there are some 27 subatomic particles which include quarks, leptons, gauge bosons and the Higgs boson. Composite subatomic particles such as protons or atomic nuclei consist of two or more elementary particles. Different quarks interact to form composite particles called hadrons. There are two groups of hadrons, baryons and mesons. Baryons include the atomic nucleus formed from protons and neutrons. Electromagnetic forces are electric fields, magnetic fields and light. In 1924 De Broglie, in his PhD thesis, proposed that just as light has both wave-like and particle-like (photons) properties, all types of matter exhibit properties of both particles and waves. This concept is crucial to the modern theory of atomic structure, particle physics and wave-particle duality. The four fundamental forces of nature are gravity, strong force, electromagnetic and weak force. Gravity is the weakest of the four fundamental forces of nature and is believed to act through a massless particle called the graviton. The strong force is the mechanism responsible for the stability of ordinary matter, holding the largest components of the mass of ordinary matter into quark elementary particles, such as the proton and neutron. The strong force is effective only at a very short distance. It is 100 times stronger than electromagnetic force, a million times stronger than the weak force interaction and 10 times stronger than gravity. The weak interaction is the mechanism responsible for the radioactive decay of subatomic particles including fermions and is caused by the emission or absorption of W and Z bosons. A fermion can be an elementary particle, such as the electron, or it can be a composite particle, such as the proton. Non-covalent interactions maintain the 3D structure of large molecules, e.g. proteins and nucleic acids, and are involved in many biological processes wherein molecules bind to one another. A non-covalent interaction involves different types of electromagnetic interactions (electrostatic, p-effects, van der Waals forces and hydrophobic effects) between molecules or within a molecule, as in complex protein structures with multiple independently folded subunits or where cofactors bind to the active site of enzymes in catalysis. Most pharmaceutical drugs act in part by the ‘binding’ of the drug to a protein, e.g. an enzyme by various non-covalent interactions. Physical subparticles and forces have well recognized properties in human biology and health and could be seen as vital forces. The absence of gravity has consequences for bone structure. Light affects vitamin D synthesis and photosynthesis. The developing understanding of forces and wave-particle duality could offer a further understanding of the fundamental processes of life, offering the prospect of exciting developments in biology and medicine. What is the action of these forces in human biology? Are they the basis of life, the underlying energy processing system, i.e. are they the basis of microsome activity, forming the ‘powerhouse’ of life? Do variations in the subatomic particles and their complexes form the basis of chemical isomers e.g. amino acids and sugars which have consequence for metabolism and