It From Bit, Oh shit

It from bit is a concept Langan highlights in section 4.5. It is originally due to John Wheeler in the paper “Information, Physics, Quantum: The Search For Links”. Langan summarizes it by saying that because reality develops itself as information in the form of quantum events, every it, every “thing”, is ultimately bits - units of binary information. This isn’t quite what he says, actually, he says that every it derives it’s ultimate significance from bits.

The original Wheeler paper says every item ultimately has an immaterial source and explanation. That reality arises from posing yes or no questions and registering a response - that this is ultimately a participatory universe. Wheeler goes on to give three examples: Detecting polarized photons, the Aharanov-Bohm effect, and the Beckenstein bound. Imagine you have a photon detector with a polarization filter in front of it. Only photons polarized a certain way can get through and be detected by the detector. There is then also a source emitting photons that may or may not be polarized in a way that will allow them to pass through the filter. We then watch the detector: do we see it register or not? Yes or no? 1 or 0? True or False? If yes, we say it was the photon. As far as we - and really any real world system - is concerned, we only have the single bit measurement of the photon (and presumably knowledge of its emission). Any notion of the photon existing in between the emission and the detection is extrapolated from the data. As far as the real world is concerned the existence of the photon is in that single bit of abstract information, an immaterial source.

We will (hopefully) cover the Beckenstein bound and the Aharanov-Bohm effect before moving on to other Wheeler principles - they may both be relevant mathematically to “the boundary of the boundary is zero”.