Zenith Grant Awardee
Wojciech Zurek
Theiss Research
Project Title
Events, Irreversibility, and the Objective Past of a Quantum Universe
Project Summary
We perceive sequences of events arranged into histories. In a classical world that evolved according to Newton’s dynamics history was a sequence of causally connected events: What happened next was completely determined by what happened before, and, ultimately, by the initial condition. In quantum physics this deterministic progression is no longer the only possibility. Often (as in quantum measurements, or in the famous Schroedinger cat gedankenexperiment) history can split into a superposition of several possibilities (corresponding, e.g., to the measurement outcomes or to the fate of the cat). I will study how such superpositions of possibilities turn into hard facts, so that, in the end, we can expect there is a single objective past of the quantum Universe we inhabit. The main ingredient I shall rely on is the idea that a history is not an abstract entity, but, rather, our reconstruction for what has happened that is based on evidence, on the records of events (that can be arranged into a causally connected sequence, a history). When these records are inscribed, in many copies, into the environment that is also responsible for decoherence, the history becomes indelible. Such histories comprise objective past of our Universe.
Technical Abstract
Quantum Darwinism recognizes role of redundant records in identifying, as candidate events, quantum states with resilience characteristic of objective classical reality. I will explore implications of redundancy for consistent histories and study irreversibility that accompanies imprinting of records. Events are causally connected, so histories matter in defining them: Only some events can follow a certain past event, so in that sense events record one another. Moreover, probabilities of consistent sets of histories must add up in accord with Boolean logic. Quantum Darwinism suggests that events comprising objective past should be recorded in many subsystems of the environment. Such redundantly recorded past becomes independently accessible to many observers, who can reconstruct it and arrive at compatible conclusions. I will investigate whether redundant records suffice to select, from the many alternative sets of consistent histories (most of them flagrantly non-classical), sequences of events with characteristics of the familiar classical past. I will also investigate similarities and differences between quantum and classical information flows, and study their relation to the familiar sources of the second law (e.g., decoherence). The origins of irreversibility in quantum measurements will be explored operationally – through observer’s ability to reverse measurement-like evolution in quantum and classical setting.
QSpace Latest
PressRelease: Shining a light on the roots of plant “intelligence”
All living organisms emit a low level of light radiation, but the origin and function of these ‘biophotons’ are not yet fully understood. An international team of physicists, funded by the Foundational Questions Institute, FQxI, has proposed a new approach for investigating this phenomenon based on statistical analyses of this emission. Their aim is to test whether biophotons can play a role in the transport of information within and between living organisms, and whether monitoring biophotons could contribute to the development of medical techniques for the early diagnosis of various diseases. Their analyses of the measurements of the faint glow emitted by lentil seeds support models for the emergence of a kind of plant ‘intelligence,’ in which the biophotonic emission carries information and may thus be used by plants as a means to communicate. The team reported this and reviewed the history of biophotons in an article in the journal Applied Sciences in June 2024.