Category Archives: Uncategorised

The many-worlds interpretation of objective probability

Philosophers really like problems. The more disturbing and confusing the better. If there’s one criticism you cannot levy at them is that they are not willing to tackle the difficult issues. I have argued with philosophers endlessly about Bell’s theorem, … Continue reading

Posted in Uncategorised | Leave a comment

The Born rule is obvious

Philip Ball has just published an excellent article in the Quanta magazine about two recent attempts at understanding the Born rule: one by Masanes, Galley, and Müller, where they derive the Born rule from operational assumptions, and another by Cabello, … Continue reading

Posted in Uncategorised | 4 Comments

The flaw in Frauchiger and Renner’s argument

When the Frauchiger-Renner argument first came out I posted a favourable review, where I corrected the mistake in the presentation without even remarking on it. But since the authors decided to insist on the mistake, I feel the need to … Continue reading

Posted in Uncategorised | 33 Comments

Royal Society Open Science is not a serious journal

I’ve just seen that Open Science, a new journal by the prestigious Royal Society, published the article Quantum correlations are weaved by the spinors of the Euclidean primitives, by Joy Christian. The article, as numerous others by the same author, … Continue reading

Posted in Uncategorised | 4 Comments

Understanding Bell’s theorem part 4: the counterfactual version

I was recently leafing through the great book Quantum Computation and Quantum Information, and noticed that the version of Bell’s theorem it presents is not any of those I wrote about in my three posts about Bell’s theorem, but rather … Continue reading

Posted in Uncategorised | 6 Comments

Measurement results depend on the observer

In today’s arXiv appeared a nice paper by Časlav Brukner, my former PhD supervisor. Its central claim is that one cannot have observer-independent measurement results in quantum mechanics, which I bet you disagree with. But if you think a bit … Continue reading

Posted in Uncategorised | Leave a comment

A frenquentist’s dream

I’m frequently told that probabilities are the limit of relative frequencies for an infinite number of repetitions. It sounds nice: it defines a difficult concept – probabilities – in terms of a simple one – frequencies – and even gives … Continue reading

Posted in Uncategorised | 3 Comments

Mixed states and true randomness

Recently two nice papers appeared on the arXiv, the most recent by Galley and Masanes, and the oldest by López Grande et al.. They are both – although a bit indirectly – about the age old question of the equivalence … Continue reading

Posted in Uncategorised | 5 Comments

What is cool about quantum teleportation?

Everybody™ thinks that quantum teleportation is lame. Even science-loving xkcd thinks quantum teleportation is lame, and has a comic mocking it: This breaks my heart. I want to actually defend quantum teleportation, and show that Randall Munroe is wrong. Quantum … Continue reading

Posted in Uncategorised | 1 Comment

Wallace’s version of the Deutsch-Wallace theorem, part 2

To conclude the proof of Wallace’s version of the Deutsch-Wallace theorem, we shall add the Equivalence theorem from the previous post to a pretty weak decision theory, and show that if you are rational and live in a universe described … Continue reading

Posted in Uncategorised | 8 Comments