The causal sets programme is an approach to quantum gravity. Its founding principle is that spacetime is fundamentally discrete and that the spacetime events are related by a partial order. This partial order has the physical meaning of the causality relations between spacetime events.

The programme is based on a theorem by David Malament which states that if there is a bijective map between two past and future distinguishing spacetimes which preserves their causal structure then the map is a conformal isomorphism. The conformal factor that is left undetermined is related to the volume of regions in the spacetime. This volume factor can be recovered by specifying a volume element for each spacetime point. The volume of a spacetime region could then be found by counting the number of points in that region.

Causal sets was initiated by Rafael Sorkin who continues to be the main proponent of the programme. He has coined the slogan "Order + Number = Geometry" to characterise the above argument. The programme provides a theory in which spacetime is fundamentally discrete while retaining local Lorentz invariance.

Helen Fay Dowker (born 1965 in Manchester, Lancashire) is a British Theoretical Physicist at Imperial College London.

As a student, she was interested in wormholes and quantum cosmology. Having studied at the University of Cambridge, Dowker was awarded the Tyson Medal in 1987 and completed her Doctor of Philosophy under the supervision of Stephen Hawking in 1990.

Fay Dowker was later a Postdoctoral Researcher at the Fermi National Accelerator Laboratory, at the University of California at Santa Barbara and also the California Institute of Technology.

She is currently a Professor of Theoretical Physics and a member of the Theoretical Physics Group at Imperial College London and an Affiliate of the Institute for Quantum Computing. She conducts research in a number of areas of theoretical physics including quantum gravity and causal set theory.

Dowker was previously a Lecturer at Queen Mary, University of London.