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Showing posts from July, 2016

Civil War in Yemen

Yemen is a country which has been gripped in conflict and civil war since March of 2015. Houthi militia and deposed Saudi president Saleh are fighting against the Saudi backed forces of president Hadi and anti-Houthi militia. Both sides are fighting against Al-Qaeda and ISIS and all stand accused of war crimes.

The U.S. and UK governments are currently backing the Saudi lead coalition which has used British cluster bombs to kill thousands in Yemen. Much of these sales were done by the U.S. and over looked by the ever incompetent Hillary Clinton and her state department but the British government has sold £2.9 billions worth of weapons to the Saudi government. Including £1 billions worth of bombs. Im writing this post because I believe these sales are in direct violation of the Arms Trade Treaty.

Amnesty international, the United Nations, the European Union, Oxfam, Safer World, and Human Rights Watch have all acknowledged the use of British-Saudi weapons in Yemen but our government re…

Fluid Dynamics for Cosmology

In a previous post I derived the first of Friedmann's equations but the equation cannot be solved unless we know how the density of the universe changes over time. In cosmology the Roberston-Walker metric is formulated with fixed coordinates for fundamental particles which do not vary with time. We can therefore assume that the matter and radiation which fills the universe is describable as an ideal fluid. The evolution of the density is going to depend on the pressure present in the universe, which depends on the material which fills the cosmos. The assumption I make is that there is a unique pressure for every density. This is the simplest assumption because under this condition pressure does not contribute any additional force.

This is the equation of state and gives us enough to solve the equation once we derive it. Consider the first law of thermodynamics

This applies to an expanding volume, V the energy of this volume is given by

The change in energy of the system then requ…

Consistent Histories

Consistent Histories is an interpretation of quantum mechanics that started in 1984 with a statistical physicist Robert Griffiths, who discovered a set of criteria designed to assign conditional probabilities based on classical rules of probability. The interpretation was picked up by Roland Omnes in 1988 who gave the theory a formal logical systemisation and later by James Hartle and Murray Gell-Mann, who emphasise the role of decoherence in replacing collapse of the wave function in 1990.

The interpretation starts with with subspaces of the Hilbert space and applies to closed systems by treating them as a sequence of events or "histories". An event specificies the properties of a system as a projection operator on the Hilbert space, where:

A "homogenous history" is taken as a series of such operators. The evolution of these histories from event-to-event is stochastic and evolves according to the Schrodinger equation in Griffiths' original formulation. Only h…

Newtonian Cosmology

I thought it would be useful to write a short series of posts explaining key and well established concepts in physics starting with cosmology, in order to have something to refer back to, when I write on more speculative topics like inflation. I'll start off then with the most important equation in all of Cosmology, the first Friedman equation, then I hope to discuss the fluid equation, the acceleration equation (the second Frideman equation), the Robertson-Walker metric and physical meaning and value of which appears in the Friedman equationsI may add to this list later on, but currently I plan to keep it at five posts.

I will however also discuss at some point, Einstein's field equations for now I won't, as these involve tensors and I don't right now feel like explaining these, my derivation here is entirely Newtonian but one should be aware that the first Friedman equation can also be derived by taking the relevant features our universe into account, i.e., it&#…