Physics Stuff
Odds and Ends for the Classroom and Beyond
Some answers, useful resources and more questions.
Pity the Learner...
Why do we stop answering rhetorical questions?
Only the clever maintain a childlike enthusiasm that keeps them open minded.
All that Blusters is not Gold
Got you thinking?
Physics & Maths at School
Electricity and Energy Conservation
Electrical circuits obey conservation laws:
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charge conservation [Kirchhoff 1]
net flow of charge at a point in circuit is zero)
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energy conservation [Kirchhoff 2]
energy per charge into circuit: electro motive force (emf) must equal the energy density drained from circuit:potential differnece (pd).
The conservation laws, as in the first law of thermodynamics are not everything?
Conservation of energy (1st law of thermodynamics) relates potential, kinetic energy to heat transfer. Implications of second law is that heat will not flow spontaneously from a cold to hotter body, rather it moves down temperature gradients. Energy always diffuses into a less useful and disorganised pattern and every isolated system grows more disordered with time. This is captured in the system's Entropy (Clausius who coined it took from the Greek for transformation) noting that the ratio of the heat content of a closed system to its absolute temperature always increases.
Gibb's free energy will tell you whether a chemical reaction will take place spontaneously. Helmholtz enthalpy takes into account work done against external pressures in chemical reactions.
Maxwells equations rewritten by Heavyside as 4 sets of vector calculus equations describe the divergence and circulation properties of electric and magnetic fields.
Magnetic fields lack divergence (no monopoles) and electrical circulation. The two fields are relative and complimentary in the sense that they can induce the other: circulating currents induced by moving magnetic fields need not be formed of actual moving charges in a closed wire circuit . As such named this fictitious current the Displacement current which is a changing electric field.
In cosmology while space-time (s-t) expands, light from stars at the furthest distance of the universe effectively travels faster than the speed of light as the s-t between us and the star stretches in the time it takes light to reach us, making them more than 14 billion light years away.
With new theories of cosmology suggesting the universe is hyperbolic with negative curvature and set to expand and accelerate what does this mean for the conservation of energy if it arose from a single Big Bang with finite energy? That First Law of Thermodynamics comes from the very assumption of the homogeneity of time (so we can represent time by the number line ticked off by synchronised clocks through space) just as momentum conservation comes from spatial homogeneity (a uniform ruler is suitable).
As such if both these are plainly not true as the latest cosmic background pictures from the Plank Satellite of ESA confirm, along with lack of isotropy, perhaps we get conservation only if we include the darkness of dark matter and energy?
Thermodynamics, Kinetic theory of Gases
Cosmology
Maxwells Equations and Faraday's Field Concept
In The News
Conspiracy exploits Science's scepticism
Occam's razor says simplest interpretation is always preferable while Occam's broom sweeps inconvenient facts under rug: conspiracy theorists leave out a few relevant facts which is the extreme form of the inverse of cherry picking.
Sep 2013
Published Papers by Lee McC-J
Einstein's field Equations and Linear systems. The relationship between Einstein’s Field equations and classical higher spin field equations is investigated using two-component spinor valued differential forms. Linear systems of equations associated to both the vacuum and coupled gravitational matter field equations are constructed. The latter equations are shown to be the integrability conditions of the linear systems.
GL(2,C) extension of the Tung-Jacobson chiral quadratic spinor Lagrangian. The local symmetry group in the chiral quadratic spinor Lagrangian of Tung and Jacobson is extended from SL(2,C) to GL(2,C). The resulting field theory includes both spin-1 and spin-2 fields. The field equations admit solutions which are also solutions of the Einstein-Maxwell equations, including some with anti-self-dual Weyl tensor and anti-self-dual Maxwell field.
Aphorisms from those of note
It is mere rubbish, thinking at present of the origin of life; one might as well think of the origin of matter
Charles Darwin
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..I find myself attached to one corner of this vast expanse [universe] without knowing why I have been put in this place rather than that, or why the brief span of life alloted to me should be assigned to one moment rather than another of all eternity which went on before me and that which will come after me
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Blaise Pascal
Another thing I must point out is that you cannot prove a vague theory wrong.
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Richard Feynmann
Maxwell's theory is Maxwell's system of equations
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Heinrich Hertz (1886)