The Quantum Thomist

Musings about quantum physics, classical philosophy, and the connection between the two.
More recent articles

Are fundamental particles of matter indestructible?

Last modified on Sat Jul 13 18:38:44 2019


I discuss what is possibly the most famous equation in physics, and some of its consequences.

Aristotelian Potentia and the measurement problem.

Last modified on Sun Dec 31 18:33:48 2017


One of the big philosophical problems in quantum mechanics is the measurement problem. Measurement plays a key role in QM. The simplest interpretation of QM is that there is a wavefunction which describes the likelihood that observers will measure a particle to be in a particular state. This wavefunction has two different modes of evolution in time. The first is a deterministic and smooth evolution, governed by some differential equation (perhaps the Schroedinger equation or Dirac equation). This happens when nobody is looking at the particle. But when somebody looks at the particle, the wavefunction suddenly and indeterminately jumps into one state or another. There are numerous problems associated with this: Why does the observer play such a key role? How do we define measurement? Under what circumstances does the wavefunction collapse? Why is one part of the evolution deterministic and the other indeterminate? And so on. Clearly, something is either wrong with the theory or with the way we are thinking about the theory.

In this post, I take a look at the measurement problem, and whether identifying quantum mechanical states with Aristotelian potentia can help resolve it.

Why is quantum physics so weird (Part 2)?

Last modified on Sat Jul 13 18:33:29 2019


I continue my discussion of the quantum theory of uncertainty. Having outlined the axioms of classical theory of uncertainty (probability), I describe which of them don't apply in the real world, and what they should be replaced by.

Why is quantum physics so weird?

Last modified on Sat Jul 13 18:38:25 2019


In classical physics we use probability as a numerical representation of uncertainty. Indeed, not only in classical physics: this is our standard way of understanding the world. Whenever a bookmaker quotes an odd, or we say there is a 50-50 chance of Donald Trump creating a diplomatic row with one of his tweets in any given day, we are using probabilities to parametrise uncertainty. Even those who don't understand the details of the mathematical description of probability will still intuitively think in a way consistent with it.

Probability is convenient because probabilities can be used to directly predict frequency distributions. A probability distribution is proportional to the frequency distribution expected on average over a large number of samples. Frequency distributions are natural and intuitive, because all they are is a count of different types of object. And counting is something which even babies know how to do. The mathematics behind probability is thus the same as the mathematics behind counting. And so, probability comes naturally to us.

However, when we come to quantum physics, things are a little bit different, and probability doesn't work as a representation of uncertainty.

In this post, I briefly introduce the axioms behind probability theory, so that we can see in later posts which of them are violated by quantum physics.

What must we do?

Last modified on Sun Dec 3 16:36:07 2017


Bertrand Russell concludes his essay by saying that we should proceed with an unfettered and free mind, ignoring the ignorance of past thinkers. I ponder what that means.

Is fear the foundation of religion?

Last modified on Sun Dec 3 16:41:25 2017


Bertrand Russell tries to find a reason why people are religious. His answer is that it is fear of the mysterious and death.

Does Christianity inhibit moral progress (part 2)?

Last modified on Sun Dec 3 16:41:10 2017


Bertrand Russell continues his argument that the Churches oppose moral progress. In this section, he discusses two aspects of Church teaching with which he disagrees: the Church's opposition to divorce, and the Church's denial that human happiness is the basis for morality.

Does Christianity inhibit moral progress?

Last modified on Sun Dec 3 16:40:53 2017


Bertrand Russell's next argument against Christianity was that the organised Churches opposed all moral progress that had been attempted in the world. I argue instead that the Churches, when faithful and succumbed to follow the patterns of the world, have been the continual enemies of moral regress, just as they are today.

The goodness of Jesus, Part 3: Was Christ Moral?

Last modified on Sun Dec 3 16:40:38 2017


Russell defined Christianity in terms of two core beliefs: that God exists, and that Jesus was a uniquely morally good and wise person. Having discussed the arguments for God's existence, and found his misrepresentations of those arguments unconvincing, Russell now turns to the Character of Christ. The third and final part of this discussion was about whether Jesus' beliefs and attitude were indeed moral.

Absence

Last modified on Tue Oct 9 14:53:44 2018


Normal service to resume next week.

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