Nice simple explanation of Shannon Entropy.

Information, Uncertainty and Shannon Entropy - The Math Introduction at Nonoscience

The phrase ‘Information Entropy’ is one of the most confusing in science, since entropy is the lack of infomation. But the problem is not with the idea of equating information theory and entropy, just eth sloppy phrasing. Information Entropy means Entropy within the concept of information science (as opposed to thermodynamics, for example).

Make the electrodes in an ion trap cold and you can stop qubit decoherence.

science, engineering & technology news

New Yorker article on Lee Smolin’s visceral attack on string theory.

‘The paradoxical situation of string theory

Kathy Young for Capital News 9:

“By the end of the week, the universe could be expanding, with the addition of three new planets to our solar system.”

Hilarious. Given the relative size of the known Universe to our solar system, this is the equivalent of saying: “By the end of the week, the earth could be expanding, with the addition of three grains of sand on a beach in Florida.”

Capital News 9 | 24 Hour Local News | HEADLINES | A cosmic change

A quarter of everything that exists has just been found.

BBC NEWS | Science/Nature | Team finds ‘proof’ of dark matter

Thermodynamic entropy vs information entropy - Advanced Physics Forums

“We can choose to look at thermodynamic entropy in two different ways. One approach would say that a high entropy state is information poor because there is so much disorder, and the disorder is essentially random. The other approach would say that a high entropy state is information rich because to truly describe the exact state of randomness in all its gory detail would require lots of information.”

This outlines the confusion of the difference in the ’sign’ between Shannon and Boltzmann entropy.
It is basically a confusion over the difference between a state which has meaning to a particular observer, and the notion of absolute meaning where bits of information are stored in the smallest possible moving (hence thermodynamic) particles. What if the latter case were subjective?

There is possibly no such thing as absolute entropy, or energy or information for that matter, merely the capacity to interact with a decoder or remote system. This is possibly explained in terms of entropy by comparing microstates to macrostates (think numbered balls vs a bunch of similar marbles).

(Sorry for the slightly random rant - I’m using this blog for public notes about entropy, in case anyone else is interested in this stuff)

Nice explanation of diff between Shannon and Boltzmann etropy.

Thermodynamic entropy vs information entropy - Advanced Physics Forums

The information entropy is the log of the number of accesible states, and is dimensionless.

The thermodynamic entropy is equal to the information entropy times the Boltzman (sic) constant. (kB = 1.38×10^-23 J/K) so the thermodynamic entropy has units of energy per degree kelvin.

It is worth noting that present day computers process so little information compared to the number of equivalent thermodynamic states accesible to them, that the information entropy of the device is insignificant compared to the thermal entropy. I believe this means that present day computers operate nowhere near the thermodynamic limits of computation, so in a certain sense the equivalence of the two forms of entropy is irrelevant except that it does allow one to place theoretical limits on the process of computation.

Entropy macrostates vs microstates

The Panda’s Thumb: Entropy: Common pitfalls

Scientists Say They’ve Found a Code Beyond Genetics in DNA - New York Times