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Why Quantum Statistics?

Consider the following scenario. An initial measurement indicates that two indistinguishable particles...

To Be Is To Be Measured (III: Contextuality)

In their seminal paper of 1935, Einstein, Podolsky, and Rosen (EPR) put forward the following criterion...

The 2-Slit Experiment Revisited (2: Interpretation And Why It's So Hard...)

Continued from the last post.Discounting the Bohmian song and dance, we are led to conclude that...

The 2-Slit Experiment Revisited (1: Calculation)

According to Feynman, the 2-slit experiment with electrons "has in it the heart of quantum mechanics"...

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Ulrich MohrhoffRSS Feed of this column.

Born and raised in Germany, I joined the Sri Aurobindo International Centre of Education (SAICE), Pondicherry, India, as an undergraduate student in 1972. From 1974 to 1978 I studied physics at the... Read More »

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Young’s experiment, new revised

Young’s experiment, new revised

Jun 04 2011 | comment(s)

If a particle satisfies the minimum mandated by the uncertainty relation and is subject to no force, the fuzziness of its momentum causes the fuzziness of its position to increase, while the fuzziness of its momentum remains the same. So the amount of information available for predicting the outcome of a momentum measurement remains the same, while the amount of information available for predicting the outcome of a position measurement decreases.
To Be Is To Be Measured (Part 2)

To Be Is To Be Measured (Part 2)

Jun 02 2011 | comment(s)

Last time I invited you to consider the following "game": Three "players" (Andy, Bob, and Charles) compete agains three "inter­roga­tors".

Two things can happen: either all players are asked for the value of X, or one player is asked for the value of X while the two other players are asked for the value of Y. The pos­sible values of X and Y are +1 and −1.
To Be Is To Be Measured (Part 1)

To Be Is To Be Measured (Part 1)

May 22 2011 | comment(s)

Quantum mechanics allows us to perform the following experiment (see the article by David Mermin in Physics Today Vol. 38 No. 4):

A Simple Derivation Of Heisenberg's Uncertainty Principle

A Simple Derivation Of Heisenberg's Uncertainty Principle

Apr 28 2011 | comment(s)

In his recent blog post "The World Is Not Woven From Real Stuff", Sascha Vongehr wrote:
Some merely claim that we need quantum mechanics so that the electron does not fall into the atom’s nucleus. Any classical electric charge would spiral into the atom's nucleus. The material that they make up would collapse.... Well, how convincing is this argument? Does it convince you? It would not convince me without a severe dose of already knowing at least a bunch of electromagnetism. Why could there not be some other, more intuitive explanation of why atoms do not collapse?