Information About What?

[dianahsieh]

Originally posted by Diana from NoodleFood,

On a mailing list to which I subscribe, Travis Norsen posted the following message:

A friend of mine who does research on Bohm's version of quantum physics pointed me to a horrible article in Nature (Dec. '05) on "The message of the quantum." It's written by the prestigious Anton Zeilinger, and its core paragraph would be a strong candidate for inclusion in a top-10 horror file collection:

"So, what is the message of the quantum? I suggest we look at the situation from a new angle. We have learned in the history of physics that it is important not to make distinctions that have no basis -- such as the pre-newtonian distinction between the laws on Earth and those that govern the motion of heavenly bodies. I suggest that in a similar way, the distinction between reality and our knowledge of reality, between reality and information, cannot be made. There is no way to refer to reality without using the information we have about it."

This is actually an expression of a semi-trendy movement in the foundations of QM recently -- the idea that QM is fundamentally about "information" (which concept thus evidently replaces "matter" as the basic referent of physical theories). [Physicist John Archibald]Wheeler's pithy name for this movement (which he supports) is brilliant (-ly bad): "it from bit."

The full article is available online to subscribers. (Any educational institution worth its salt should have a subscription.)

Travis submitted the following letter in response to the article to Nature, but it wasn't printed. He's graciously allowed me to post it to NoodleFood.

Anton Zeilinger (Nature, Vol. 438, 8 Dec. '05, pg 743) claims that anti-realism is "the message of the quantum". He suggests that "the distinction between reality and our knowledge of reality, between reality and information, cannot be made." This commits the error that philosopher Ayn Rand dubbed "the fallacy of the stolen concept". For example, one cannot validly argue against the institution of private property by claiming that "property is theft". The concept "theft" is rendered literally meaningless outside of a context in which property rights are considered valid. Equally vacuous is the idea that, really, there is no reality but only "information". "Information"

means

information

about

something. There can be no information without something real that the information is information about, no awareness without some object which is the object

of

the awareness. Or in Rand's words: "If nothing exists, there can be no consciousness: a consciousness with nothing to be conscious of is a contradiction in terms." This is the fundamental reason that any argument for anti-realism is unavoidably self-defeating.

Zeilinger's rationale for his anti-realism also deserves comment. He advises that "We have learned in the history of physics that it is important not to make distinctions that have no basis -- such as the pre-newtonian distinction between the laws on Earth and those that govern the motion of heavenly bodies." Good advice. But rather than realism, isn't the obvious target here the orthodox quantum theory itself? That theory postulates two distinct laws governing the evolution of quantum states: one applying under "normal" circumstances, and the other applying when a "measurement" is made. Surely if ever there was a distinction without basis -- and hence with no place in the fundamental laws of nature -- it is this vague and shifty distinction between those physical interactions which are and aren't "measurements".

If one wishes to avoid arbitrary distinctions -- and to avoid committing conceptual grand larceny -- one must uphold some version of quantum theory (such as the de Broglie - Bohm theory) which treats all physical processes in a uniform fashion and refuses to apologize for calling them "physical".

Prof. Travis Norsen, Marlboro College

(If you're interested in such matters, Travis published a three-part article on physics in the first three issues of Axiomatic Magazine.)