The Arrow of Time: Why is the Future Different from the Past?

The arrow of time always points from the past into the future. The reason for this has been the topic of much debate, especially concerning the role of entropy. This talk will explore the often-misunderstood concept of entropy and the second law of thermodynamics that distinguishes the past from the future. This will shed light on how these fundamental principles connects the laws of physics to the laws of probability and how we can locally create order from disorder by dumping entropy elsewhere.

We will look at the orderly process of life that exploits the flow of energy from the Sun through the Earth and the dissipation of waste entropy into the cold of deep space. The same laws limit your ability to charge your phone from a bathtub full of hot water despite abundant energy. There is also the problem of building low entropy bits in silicon that can be addressed by a novel method for unprecedented depletion of the problematic natural silicon-29 isotope that otherwise causes donor atom qubit coherence to leak away into the crystal lattice.

More fundamentally, we will see how the nature of the arrow of time governs the evolution of our Universe from its low entropy origin.

Reference: Highly 28-Si Enriched Silicon by Localised Focused Ion Beam Implantation, R Acharya, M Coke, M Adshead, AB Cholizadeh, J Jacobs, JL Boland, RJ Curry, K Li, KL Moore, B Achinuq, R Cai, SJ Haigh, DN Jamieson arXiv:2308: 12471v1, Communications Materials (2024) 5:57

Short biography:
David is a Professor of Physics at the University of Melbourne where he was Head of School between 2008-2013. He has a PhD from Melbourne and held postdoctoral fellowships at Caltech (USA) and the University of Oxford. He was President of the Australian Institute of Physics from 2005-2006.

David’s research expertise in the field of ion beam physics applied to test some of the key functions of a revolutionary quantum computer constructed in silicon in the Australian Research Council Centre for Quantum Computation and Communications Technology. In 2020 he received a Royal Society Wolfson Visiting Fellowship to work on new ideas for engineering silicon with single atoms, including the production of low-entropy isotopically pure silicon for atomic quantum bits. He gives the occasional public lecture on fundamental issues in Physics.