Emil RodunerEmil Roduner is a physical chemist at University of Stuttgart and the University of Pretoria, South Africa. His colleague Tjaart Krüger is a physicist at the University of Pretoria. They have recently written a paper on the origin of irreversibility. They were kind enough to cite my 2014 paper on the origin of irreversibility, which I located in quantum events that happen at indeterministic times and move in indeterministic directions, such as the emission and absorption of photons, as discovered by Albert Einstein in 1916. Their latest work on irreversibility asks whether “memory” can be considered a new parameter for the physical state of matter? They write...
Most elementary theories describing processes of matter, like Newtonian dynamics and quantum mechanics, are symmetric with respect to time-reversal, but thermodynamics is not and describes processes that come to rest at equilibrium. A long-standing dispute is represented by the question: “How can microscopic equations of motion that are symmetric to time reversal give rise to macroscopic behavior that clearly does not share this symmetry?” The answer is commonly sought in size, with small systems being time-reversible and large systems not. It turns out that this is not correct. Time-reversibility and thermodynamic reversibility are two different issues. Thermodynamic equilibria are well-defined in terms of entropy or free energy and are reached in processes described by the “arrow of time”. But the process of equilibration can be either reversible or irreversible with respect to time, independent of the system size. There is a second criterion, the system’s memory of a previous state, which does not contribute to thermodynamic parameters. Time-reversible processes are deterministic, and if the past is understood, the future can be predicted. What destroys time-reversibility are non-Newtonian processes, mostly of probabilistic nature, like the decay of excited states.In my analysis of the creation of information structures in the universe, I have shown that the reduced local entropy (so-called "negative entropy") of such structures requires that an amount of positive entropy equal to or greater than the negative entropy must be carried away from the structure, or the new pocket of negative entropy (also information) will not survive. For example, in the early years after the origin of the universe, atoms were repeatedly being formed from protons combining with electrons. But the temperatures were so high and the radiation field so intense, that photons (some emitted by electrons as they fell into bound atomic states) immediately ionized atoms back to their elementary particles. Some 380,000 years after the origin, the expansion of the universe had cooled the temperature to a few thousand degrees Kelvin, and even more importantly created vast numbers of new phase space cells that provided a cool thermodynamic "sink" into which the "source" of hot photons could radiate. After that somewhat inaccurately called "recombination era" the combinations of protons and electrons into hydrogen atoms became stable. The free electron gas that was the major source of opacity preventing the photons from traveling very far disappeared. The universe became transparent to radiation, allowing astronomers today to see all the way back to that recombination era some 13.75 billion years ago to the isotropic microwave background radiation coming to us from all directions. We are looking at the residue of the "Big Bang." The original blackbody spectrum of 5000K radiation (approximately the white light from our Sun with wavelengths from 400 to 700 nanometers) has been red-shifted to much longer wavelengths from 1 to 2 millimeters. Based on a 1934 suggestion of Arthur Stanley Eddington and the 1970's work of my late Harvard colleague David Layzer, I have shown that the information structures in the universe today (from subatomic particles like electrons and quarks, to the galaxies, stars, and planets, as well as living things on Earth) are all dependent on a two-stage cosmic creation process. In the first stage, there must be multiple indeterministic possibilities for different quantum arrangements of the particles of future structures. If/when the new arrangement has created a new information structure, energy released in the new binding of particles must be carried away in the second stage. Note if there were only one possibility, information would be a constant and only one (predetermined?) possible future. The great theoretician of quantum mechanics, John von Neumann, described the importance of new information created in a quantum measurement. He defined two fundamental processes in quantum mechanics, one the "causal" deterministic information-preserving time evolution of a quantum system between measurements, the other the indeterministic information-creating measurement itself. Von Neumann said the deterministic causal evolution process "does not reproduce one of the most important and striking properties of the real world, namely its irreversibility, the fundamental difference between the time directions, 'future' and 'past.' " He also said that the indeterministic measurement is "statistical" and causes a "change of the probabilities and the expectation values. Indeed, it is precisely for this reason that one introduces statistical ensembles and probabilities!" See von Neumann's landmark book, Mathematical Foundations of Quantum Mechanics, (English translation, pp.357-358) Roduner and Krüger's study of memory critically involves the roles of irreversibility and the "arrow of time." Von Neumann saw those two issues as central to understanding quantum mechanics. Memory depends on the recording of information in brains/minds and the recall/reproduction or "playback" of that information on demand, when needed by an agent to make a decision on the next action or thought. See our model of the mind as an Experience Recorder and Reproducer. When particles collide, a quantum process can erase the past path information that would be needed to reverse their paths. This is the origin of irreversibility. But an interaction of a particle with a measurement apparatus can also generate new path information that allows us to predict (within some uncertainty) future events. In quantum events, information can be both destroyed and created. According to the second law of thermodynamics, entropy in the universe is is always increasing. But counterintuitively, we now also know that new information and new knowledge is also increasing. Both disorder and order are increasing in the direction of the "master arrow of time," the expansion of the universe, as shown in 1975 by my Harvard colleague David Layzer, based on a 1935 suggestion of Arthur Stanley Eddington. Normal | Teacher | Scholar