Mon 2nd March “When stars fall into black holes: going beyond the equivalence principle.” – Dr Adam Pound, STAG
One of the cornerstones of Einstein’s theory of general relativity is the equivalence principle, which says that in a sufficiently small patch of spacetime, physics is just the same as in any other sufficiently small patch anywhere else in spacetime. One consequence is that a sufficiently small and light object in free fall in a gravitational field, no matter its internal composition, always moves on a “geodesic” (a path of longest time) in spacetime.
But this is only an approximation. In reality, any patch has finite size, and any object has both finite size and finite weight (or more precisely, creates a finite gravitational field). So how exactly is the equivalence principle corrected when these facts are accounted for?
Remarkably, gravitational-wave astronomy will soon allow us to answer this question with incredible precision. LISA, a gravitational-wave detector that will operate in outer space, will observe the inspiral of black holes and neutron stars, weighing roughly as much as our Sun, into supermassive black holes millions of times larger. Over the space of a year or two, as it slowly falls inward, the smaller object in such a system will execute hundreds of thousands of intricate orbits around the enormous black hole, and its tiny deviations away from geodesic motion will be precisely encoded in the gravitational waves it creates.
This talk will discuss these so-called “extreme-mass-ratio inspirals”, gravitational-wave astronomy, and what they might teach us about both general physics and the nature of the huge black holes that reside at the centres of galaxies.
Adam Pound is a Royal Society University Research Fellow and permanent member of staff in the School of Mathematical Sciences at the University of Southampton. He has published in fields ranging from experimental polymer physics to theoretical astrophysics. His research focuses on classical general relativity and gravitational-wave science, where he has made many contributions to the theoretical understanding of relativistic motion and binary mechanics. He is a member of the LISA Consortium, a network of about 1000 scientists involved in the LISA mission, and he leads the Consortium’s ongoing effort to develop theoretical models of extreme-mass-ratio inspirals.
Mon 3rd February 2020 “Alcohol: our favourite poison” – Prof Julia Sinclair
Alcohol is pervasive in our society, although almost 20% of the population self-identify as ‘non-drinkers’. Everyone knows someone who has a problematic relationship with alcohol.
The stigma surrounding problematic alcohol use means that there are no influential, fund-raising patient groups demanding improvements in treatment or to drive further research.
Politicians and policy makers have a marked ambivalence to an evidenced based alcohol policy, which is perhaps not surprising given significant lobbying by the alcohol industry: and £1.3 million worth of subsidised alcohol sold in House of Commons bars in a single year.
Among health professionals ‘alcohol health literacy’ is poor, with only a minority able to accurately estimate the alcohol content of commonly consumed drinks, to make an objective assessment of risk – a lack of competence that would be seen as negligent in any other disorder (e.g diabetes).
We are with alcohol where we were with smoking 30 years ago – do we want to catch up?
“No animal ever invented anything as bad as drunkenness- or so good as drink”
– G. K Chesterton
Julia Sinclair is Professor of Addiction Psychiatry in the Faculty of Medicine at the University of Southampton, and leads the alcohol care team at University Hospital Southampton.
Her clinical roles include developing an integrated alcohol strategy across local clinical services, offering direct clinical care, and work with Regulatory Bodies including the General Medical Council. She is Chair of the Addiction Faculty of the Royal College of Psychiatrists. She has contributed to several clinical guidelines including the National Institute for Health and Care Excellence (NICE) guideline for the management of harmful drinking and alcohol dependence (CG115), the British Association of Psychopharmacology guidelines on the management of substance use in psychiatric disorders, and is currently working on the first clinical guideline for Public Health England. She is a Trustee of the Society for the Study of Addictions (SSA), which aims to broaden and promote the scientific understanding of addiction, and to help clinicians and policy makers get research evidence into practice.
Julia’s research is clinically focused, investigating how biological, psychological and social mechanisms interact in this group, and their impact on clinical outcomes in terms of prevention, engagement and response to treatment. She is a champion for Southampton Public Health “Dry January” campaign, and is looking forward to being at Winchester Café Sci on 3rd February!
6th January 2020 “Driving-us-closer-to-greener-transport: sustainable lightweight composites” Professor Hom Nath Dhakal
The principle of Hom’s research is combining organic materials with plastics to create composite laminates.
The goal is to see these being used for products such as car bumpers and door linings. If you’re picturing a car partly made of plant fibres and imagining it would break if you blew on it, think again. Part of Hom’s research is about proving they have the necessary strength.
He and his team conducted several experiments to find out what happens to their materials when loads are applied. There are different mechanical properties to consider – from impact strength, to flexural strength, to fatigue – depending on what a biocomposite might be used for.
Professor Hom Nath Dhakal is a Professor of Mechanical Engineering at the School of Mechanical and Design Engineering, University of Portsmouth, U.K. In addition, he is also a docent professor of bio-based materials at the faculty of textiles engineering and business, University of Borås, Sweden.
He leads the Advanced Materials and Manufacturing (AMM) Research Group within the School of Mechanical and Design Engineering. His principal research interest lies in the design, development, testing and characterisation of sustainable lightweight composites, nanocomposites, natural fibre composites and biocomposites including their mechanical (tensile, flexural, low-velocity impact and fracture toughness), thermal and environmental properties (dimensional stability under harsh environments).
He is a Fellow of the Higher Education Academy (HEA), Chartered Engineer (CEng), a Fellow of the Institution of Engineering and Technology (FIET), Fellow of the Institute of Materials, Minerals and Mining (IOM3) (FIMMM) and a member of the American Society for Composites (ASC).
Professor Dhakal is the author/co-author of over 100 publications in the area of light weight sustainable composite and biocomposites which has attracted well over 2400 citations with an h-index of 22; i10-index of 41 (Google Scholar as of 24/05/2019); ResearchGate score of 32.66, and higher than 90% of ResearchGate members. He has successfully supervised many PhDs as a Director of Studies; and been an external examiner for many PhDs nationally and internationally. He is a member of international scientific research committees; established national and international industrial, professional and academic networks.