Information Theory - Part 5: Everything or Overhyped?

The most famous thought experiment in quantum theory, Schrodinger’s cat, raised a highly problematic question: At what size does the weirdness of quantum phenomenon give way to the “normal” behavior we observe all the time?

Nothing in the maths of quantum theory put a size limit. Nor does the maths explain what constitutes an “observation” of a quantum entity. Could only living entities could make an observation? Or did instruments count too?

The accepted answer today is something called decoherence, writes Charles Seife in Decoding the Universe. “Decoherence” refers to any interaction between two items in the universe (light, matter, anything else). Every such interaction constitutes a measurement made by nature. An extraction of (there’s that word again) information. The tinier or colder or more isolated something is, the longer it can stay without interacting with any other piece of nature, i.e., the longer it takes before another part of nature can “measure” it. But eventually, nature will always find a way to make that measurement, no matter how tiny or cold or isolated (even in vacuum) that item may be. Conversely, those measurements happen very quickly for larger, warmer objects that we deal with on a daily basis.

Today, one of the most fundamental aspects of nature is considered to be the conservation of information, similar to the far better-known conservation of energy. So much so that many scientists believe that information can even survive the most destructive entity in the universe: a black hole.

Sound a bit too much? That information theory is at the root of everything in the universe? The speed at which information theory caught on totally unrelated fields (remember, Claude Shannon came up with Information Theory for solving telecom communication problems!) is mind-bending. That speed also meant that Shannon could be asked about all this. In his biography, A Mind at Play, Shannon said all the attention and fanfare was “pleasant and exciting”, yet:

“It carries at the same time an element of danger… (Information theory) is certainly no panacea for the communication engineer or, a fortiori, for anybody else. Seldom do more than a few of nature’s secrets give way at one time.”

Shannon’s biographers make the same point:

“He ran up against a human habit much older than him: our tendency to reimagine the universe in the image of our tools. We made clocks, and found the world to be clockwork; steam engines, and found the world to be a machine processing heat; information networks – switching circuits and data transmission and half a million miles of submarine cable connecting the continents – and found the world in their image too.”

So what is information theory, something deep and profound, or just the latest reimagination of the universe in the image of our tools?