Reflection for Public Lecture – “Decoding Reality: The Universe as Quantum Info”

Dr Vlatko Verdal introduced to us the theory that the universe exists as one big “quantum computer” that can contain a certain amount of information. Over the course of the lecture, he touched on many different topics and gave us a basic understanding of the nature of quantum mechanics, and the properties of superposition.
The gist of the lecture was that information arises out of nothing because we try to find it. He explained that a system can have certain states and that until we measure or know those states, the system is in all of those states. For this he used the famous Schrödinger’s Cat analogy. He also told us that the maximum number of ‘bits’ in the universe was around 10100 and that the current estimate of entropy in the universe is 1080.
I was very intrigued about how the universe could be seen as a certain amount of information, and was also quite perturbed by superposition. However, thanks to Dr Verdal’s explanation, I think I now have a rough feel for the subject.

Jeremy Hon

Professor Vlatko Vedral works at the National University of Singapore and another one in London. As I was working on a CenTaD project concerning atomic physics, I thought learning something about quantum physics might help. Professor Vedral introduced to me and another student, Jeremy Hon who shares the same project as me, the idea that the universe was made up of bits of information, not matter and energy. Reality emerges through the interplay between random and deterministic factors (“conjecture” and “refutation”).

Physics is all about predictions, and information about the system is crucial. Laplace said: “Gimme all positions and velocities of all particles and I will tell you the future exactly.” Maxwell said: “Gimme all positions and velocities of all particles and I will violate the Second Law.” Imagine a special porous membrane (“Maxwell’s demon”) that determines the velocities of all particles. It can differentiate “hot” and “cold” particles and can separate them, causing a difference in temperature in both sides of the membrane, which can be utilised. In effect you have created energy, shockingly enough. However, the consideration of information retrieval and utilization in the conservation of energy will push this scenario back into the realms of physics.

There were several interesting ideas put up by Professor Vedral. First, consider a stream of photons shot at a beam splitter, 50-50 reflection or passing through. This process of deciding where the individual photons go is random. However, combining both new streams of photons and aiming them at a new beam splitter actually merges them into a single path, instead of two “more random” paths. This has something to do with the fundamental properties of “quantumness” and is not explained, possible because nobody understands it as yet.

Next, information is the logarithm of one over probability. The higher the probability, the lesser the information. The higher the probability of the sun rising in the east tomorrow, the less newsworthy the news is. This formed Shannon’s paper, which was not extrapolated upon for ten years due to its brilliance until Kelly, his colleague, published a paper on betting wealth growth.

Professor Vedral also, in a very self-referencing half-joking manner, said that biology was dependent on chemical processes. Chemistry was in turn dependent on physics and atomic physics in particular. Mathematics, although sometimes described as the language physics uses, is somehow borne from physics itself.

He pointed out to several cases where quantum entanglement has been considered in explaining these scenarios: Birds have mini-compasses in their bodies that allow them to navigate. However, the polarity of the B-field (magnetic field) will not change the flight of the birds, instead, B-line inclination (B-field at an angle), light, and B-strength will. Photosynthesis is 99.99% efficient, much higher than the 20-odd % we can achieve with solar cells. Photons striking a particular atom in the leaf will excite all electrons to fill all different shells and subshells, but they all return back to a single site and absorb energy for the leaf as a whole.

There were several papers and books Professor Vedral recommended:
Ghosh et al., Nature 2003, regarding the quantum entanglement observed in large masses of LiHo0.045Y0.955F4 (macroscopic entanglement)
Fleming et al., Nature 2008, regarding the efficiency of photosynthesis
The God Effect, B. Clegg, which has nothing to do with religion
Science, 1972, author unknown.
His book, Decoding Reality, which was GIVEN OUT FREE at the refreshment area. It was a more elaborated version of his lecture.