My profession is theoretical physics, especially applied to quantum physics, astrophysics and cosmology. In the last 20 years I have also worked in astrobiology, a subject that addresses the origin and evolution of life, and the possibility of life beyond Earth. In 2009 I embarked on something completely different – applying concepts from physics and astrobiology to the problem of cancer. Although these research topics seem very disparate, in my own mind they link up deep down.
I was born in London, and spent most of my life in the UK. From 1990 to 2006 I lived and worked in Australia. Then in September 2006 I moved to Arizona State University in Phoenix to establish BEYOND: Center for Fundamental Concepts in Science, a sort of “cosmic think tank” devoted to brainstorming deep foundational questions across all the sciences. We place special emphasis on the big questions of existence, such as the origin of the universe, the origin of life, the search for life beyond Earth, the nature of time and the destiny of mankind. In 2008, I was also appointed co-director of the ASU Cosmology Initiative and in 2009 I began directing the Center for the Convergence of Physical Sciences and Cancer Biology.
I began work in the field of atomic astrophysics, and worked on the problem of di-electronic recombination in the solar corona. I then moved into cosmology, and the theory of black holes, especially their quantum and thermodynamic properties. During the 1970's and 1980's I helped develop the theory of quantum fields propagating in curved background spacetime (i.e. gravitational fields). This had immediate application to the creation of quantum particles by black holes (the Hawking effect), and in the very early universe as a result of the rapid cosmological expansion.
Early work included the investigation of particle creation by moving mirrors, the response of accelerating particle detectors in a variety of scenarios and the detailed study of quantum field theory in a background de Sitter space. These ideas found later application to topics as diverse as the Casimir effect, the inflationary universe scenario, the holographic principle, wormholes and time travel. Much of my work concerned the notorious divergences associated with the quantum vacuum, which become much more problematic when the spacetime is curved. Using point-splitting renormalization, which we developed in great detail, my colleagues and I were able extract meaningful finite answers for a range of physically interesting problems. The bulk of this work is contained in my book Quantum Fields in Curved Space, co-authored with my former PhD student Nicholas Birrell.
Throughout this time, I have maintained various enduring secondary interests. The most important of these is the nature and origin of time asymmetry in the universe (see my book for more on this topic). Others include the nature and origin of life, the measurement problem of quantum mechanics, the nature of complexity, the anthropic principle and the interface of science and religion. In the 1990's I began working seriously in astrobiology. Initially I was interested in whether life could propagate between planets in the impact ejecta. I then developed some ideas about the origin of life based on its informational aspect. In the last few years I have been promoting the (speculative) theory that Earth may host a shadow biosphere of microbial life "as we don't know it" that could provide evidence for multiple origins of life. I also have an ongoing interest in SETI (Search for Extraterrestrial Intelligence) and I chair the SETI Post-Detection Taskgroup. I have championed some speculative ideas, such as broadening the search for alien technology, and one-way missions to Mars.
In 2007 I was asked to help the US National Cancer Institute interest physical scientists in novel approaches to tackling cancer. This resulted in the creation of 12 centers for physical science and oncology, and I am Principal Investigator of the one based at Arizona State University. My role is mainly to hold brainstorming workshops, as a result of which I have been developing a theory of cancer as an integral part of the evolution of multicellular life, with very ancient origins.