Web notes on quantum mechanics 9 May 2013

©Fernando Caracena 2013

Philosopher Jill North explores quantum reality

Jill North, associate professor of philosophy at Cornell University, in a recent essay1 proposes that the wave function of quantum mechanics [“the mathematical object that represents the state system at a time”] is real and fundamental, but occupies a space very different from the 3-D one we appear to live in. Although, we infer the fundamental nature of a world from the dynamical laws, we do not directly observe the fundamental level of reality of states themselves. We infer it from the dynamics of physical objects in the 3-D world.

“A match in structure between the dynamical laws and the world is evidence that we have inferred the correct space-time structure to a world governed by those laws,” writes North.

Ordinary 3-D space is not just an illusion, it exists, it is just not fundamental. It is an appearance of a deeper reality. Just as ordinary objects such as tables and chairs are not fundamental, but made up of more fundamental stuff, 3_D space is not fundamental, but is made up of the higher dimensional space of quantum states.


1 “The Structure of a Quantum World,” published in “The Wave Function: Essays on the Metaphysics of Quantum Mechanics” (Oxford University Press, 2013).


Quantum Computers

Quantum computers can solve “the travelling salesperson” problem thousands of times faster than conventional computers, because operating with quantum states they can test the outcome of selecting many competing paths very fast.



A new device combines the quantum information on two photons into that of a single photon.



Quantum encryption in networks is a promising technology that can guarantee privacy through quantum entanglement. the concept has been tested by a quantum network running secretly for 2 years.


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