Will Handley
Will Handley is a British physicist and cosmologist. He is an associate professor of astrophysics at the University of Cambridge and a Royal Society University Research Fellow.[1] He is also a Fellow of Gonville and Caius College, Cambridge.[2]
Handley is known for his work in Bayesian inference, specifically the development of the PolyChord nested sampling algorithm,[3] and for his contributions to the Planck collaboration, for which he shared the 2018 Gruber Prize in Cosmology.[4] His research focuses on the Cosmic Dawn, the curvature of the universe, and the application of machine learning to physics.
Education and career
Handley attended the University of Cambridge, where he completed a Master of Natural Sciences (MSci) in Experimental and Theoretical Physics in 2012. He continued at Cambridge to earn a PhD in 2016, with doctoral research focused on Bayesian inference in cosmology.[2]
Following his PhD, he was awarded a Royal Society University Research Fellowship (URF).[1] He conducts his research at the Cavendish Laboratory and the Kavli Institute for Cosmology, Cambridge (KICC). In addition to his research, he serves as a Director of Studies at Gonville and Caius College and lectures on relativistic astrophysics and cosmology.[5]
Research
Handley's work operates at the intersection of theoretical cosmology, high-performance computing and statistics.
PolyChord and statistical methods
Handley is the primary architect of PolyChord, a next-generation nested sampling algorithm. While traditional algorithms struggled with high-dimensional parameter spaces (the "curse of dimensionality"), PolyChord utilizes slice sampling to scale linearly with the number of dimensions.[3]
The software has been adopted as a core analytical tool by major international physics collaborations. It was employed for Bayesian model comparison in the Year 3 analysis of the Dark Energy Survey (DES)[6] and is utilized in gravitational wave astronomy to analyze data from LIGO and the future LISA mission.[7]
Cosmic Dawn and REACH
Handley is a Co-Investigator and lead of the Data Analysis Team for the REACH (Radio Experiment for the Analysis of Cosmic Hydrogen) experiment.[8] The experiment aims to detect the 21‑cm signal from the "Cosmic Dawn," the epoch when the first stars formed. Following the controversial detection reported by the EDGES experiment in 2018, Handley's team developed a Bayesian forward-modelling pipeline to distinguish the faint cosmological signal from bright galactic foregrounds and instrumental noise.[9]
Curvature of the Universe
In 2019, Handley published research analysing data from the Planck satellite, suggesting that the universe might be "closed" (positively curved) rather than "flat." Using Bayesian evidence ratios, the study argued that Planck temperature and polarization spectra favoured a closed universe model, challenging the standard Lambda-CDM model of cosmology.[10]
Awards and honours
- 2018: Gruber Prize in Cosmology (shared as a member of the Planck Team).[4]
- 2019: Royal Society University Research Fellowship.
- 2024: ERC Starting Grant for the project "Resolving cosmological tensions with diverse data."
Selected publications
- Handley, W. J., et al. (2015). "PolyChord: next-generation nested sampling." Monthly Notices of the Royal Astronomical Society.
- Handley, W. (2021). "Curvature tension: evidence for a closed universe." Physical Review D.
- Planck Collaboration (including Handley, W.) (2020). "Planck 2018 results. VI. Cosmological parameters." Astronomy & Astrophysics.
References
- ↑ 1.0 1.1 "Directory: Dr Will Handley". Kavli Institute for Cosmology, Cambridge. 13 January 2017. Retrieved 2024-01-10.
- ↑ 2.0 2.1 "Dr Will Handley". Gonville & Caius College. Retrieved 2024-01-10.
- ↑ 3.0 3.1 Handley, W. J.; Hobson, M. P.; Lasenby, A. N. (2015). "PolyChord: next-generation nested sampling". Monthly Notices of the Royal Astronomical Society. 453 (4): 4384–4401. doi:10.1093/mnras/stv1911.
- ↑ 4.0 4.1 "The Gruber Foundation Cosmology Prize 2018". International Astronomical Union. Retrieved 2024-01-10.
- ↑ "Will Handley Researcher Profile". The Alan Turing Institute. Retrieved 2024-01-10.
- ↑ Gatti, M.; et al. (11 October 2022). "Dark Energy Survey Year 3 Results". Phys. Rev. D. 106 (8): 083509. doi:10.1103/PhysRevD.106.083509. OSTI 1838498. Retrieved 2024-01-10.
- ↑ "Cosmology with gravitational waves". Monthly Notices of the Royal Astronomical Society: Letters.
- ↑ "Cambridge team unlocks Cosmic Dawn: New AI technique solves 21 cm signal paradox". NYJ Tech. Retrieved 2024-01-10.
- ↑ "Project REACH". Kavli Institute for Cosmology. March 2019. Retrieved 2024-01-10.
- ↑ "Will Handley Profile". GeniusWiki. Retrieved 2024-01-10.
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