People

Ken D. Olum

Ken Olum
Contact Info:
Tufts University
Physics and Astronomy
574 Boston Avenue
Room 304B
Medford, MA 02155

Office: 617-627-2753
Email Professor
Personal website

Research Professor

Expertise
Cosmic strings, gravitational waves, anthropic reasoning in cosmology, energy conditions in general relativity.

Research
My main area of research is the study of cosmic strings, in particular their production of gravitational waves, which might enable us to detect the cosmic string network, if it exists. Cosmic strings are one of the potential sources of a stochastic background of gravitational waves that (as of September 2020) may have been seen by pulsar timing arrays. With my collaborators, I have developed a large-scale simulation of cosmic strings, and we are the process of to going from simulation results to predictions for the gravitational wave background, with all effects included.

I also study gravitational waves and the possibilities of observing them more generally. I am an associate member of NANOGrav (the North American Nanohertz Observatory for Gravitational Waves), which observes gravitational waves using precision timing of pulsars.

I work on issues of anthropic reasoning in cosmology and how to make sense of the infinite multiverse produced by eternal inflation. I study the structure of eternally inflating universes and also the philosophy of how to get from a model of what actually exists everywhere in the universe to an understanding of what we ourselves should expect to observe.

I have worked for many years on the question of exotic phenomena such as superluminal travel and time travel in general relativity. My collaborators and I showed that, subject to certain conditions, a minimally-coupled quantum scalar field obeys the "achronal averaged null energy condition", which prohibits exotic spacetimes. I am currently working on the interaction between eternal inflation and energy conditions.