Joshi has served as President of Indian Association of General Relativity and Gravitation from 2010 to 2012[3] and President of Gujarat Science Academy (2020-2023).[7]
Research
The 2021 Nobel Prize in Physics was given to Roger Penrose (Oxford), for his discovery in 1965 that massive collapsing stars in the universe end up in space-time singularities at the end of their lives. The result was derived using Einstein's theory of general relativity. These singularities are unique fireballs, where densities, temperatures and all physical quantities are arbitrarily and extremely high. These are such unique entities in cosmos, which are seen no other places, and as yet unknown laws of quantum gravity would operate there. Penrose always assumed that such singularities must happen hidden within interiors of black holes only. That is, they are never seen by faraway observers. Such an assumption is called the cosmic censorship hypothesis. However, this assumption was never proven. Work by Joshi with his team and students has shown that singularities or fireballs can occur outside black holes. These are also called naked or visible singularities. Joshi wrote his first paper on the subject in 1986, and then published a series of papers on these fireballs, naked singularities, and black holes. This culminated in his 1993 Oxford monograph, `Global Aspects in Gravitation and Cosmology', published by the Oxford University Press, included in their pre-world war I series, The International series of Monographs in Physics.
Joshi P. S., (2012, 2008), Gravitational Collapse and Spacetime Singularities, Paperback Edition; Cambridge University Press, included in their monograph series, Cambridge Monographs on Mathematical Physics.
Joshi P. S. (2011), (ed. with R. Tikekar, N. Dadhich, K. Jotania, A. M. Vaidya, M. H. Vasavada), A Tribute to P C Vaidya, Special issue of Mathematics Today, Vol 26 (2011).
Joshi P. S. (2007), (ed. with N. Dadhich and P. Roy), Raychaudhuri Equation at the Cross-roads, a Special Volume in honour of A. K. Raychaudhuri, Pramana -Journal of Physics, Vol. 69, No. 1, Indian Academy of Sciences and Springer, Bangalore.[12]
Joshi P. S., (1996, 1993), Global Aspects in Gravitation and Cosmology, Clarendon Press (OUP), Oxford; the paperback edition, with corrections (The International Series of Monographs on Physics, Vol 87).[13]
Joshi P. S. (ed.), (1996), Singularities, Black Holes and Cosmic Censorship, Proceedings of the Raychaudhuri Session at the International Conference on Gravitation and Cosmology (ICGC95), IUCAA Publication, Pune, 1996.