Einstein’s Special Theory of Relativity was presented to the world in 1905. It had its origins in Scottish physicist J Clerk Maxwell’s work on the propagation of light. From experimental laws of electricity and magnetism he used mathematics to derive a formula for the speed of light which made no mention of what that speed might be relative to.
We were treated to an excellent talk, “Biodiversity”, given by the environmental biologist, Dr Martin Hodson, a lecturer and researcher at both Oxford Brookes and Oxford Universities. After detailing the history of the study of biodiversity, Martin gave details of the current number of identified species (1.2M) and said that it was believed that 86% of species had not yet been identified. The number and distribution of plants and therefore other living species varied depending on the habitat, with regions enjoying warmer wetter climates, such as tropical rain-forests, supporting the greatest variety of species. 17 countries contain 75% of the world’s biodiversity with hotspots in the Sunda Islands, the Philippines and Madagascar, all areas which are undergoing substantial man-made environmental change. Continue reading Biodiversity – Dr Martin Hodson
Garth Wilkinson covered the history of the basic physics of the propagation of electromagnetic waves at the velocity of light as predicted by James Clerk Maxwell & experimentally verified by Heinrich Hertz. The nature of the electromagnetic spectrum was described, and the frequency bands normally used by radars were identified in relationship to atmospheric transmission windows. Continue reading How radars work – Garth Wilkinson
Dr Luther gave a fascinating study of Einstein’s life & work, covering quantum theory, & the theory of Relativity (Special & General). His 3 PowerPoint slideshows are available at http://u3atvnetwork.org.uk/index.html.
Gwyn Williams gave a fascinating talk on the UK / French Concorde aircraft project. He had worked for 20 years as an RAF military fast jet pilot. He had then moved to work a further 20 years for the CAA at Stansted as an instructor & safety inspector on the Concorde aircraft until it left service in 2003, when he retired.
David Brown kindly organized a visit to the Building Research Establishment (BRE). 14 members visited the BRE Innovation Park on 30/05/2017. For the first hour we were provided with a PowerPoint overview of the work of BRE by the Director of the Innovation Park. This gave emphasis to the role of BRE in working to reduce buildings carbon emissions to close to zero through working with industry, education and other bodies in research and development. Continue reading Visit to Building Research Establishment 30/05/2017
- Richard Jones gave an entertaining demonstration of a number of physics toys.
- Crookes’ radiometer – an apparent perpetual motion machine, but actually dependent on radiant energy. Originally designed by Crookes to demonstrate differential radiation pressure between black & silvered surfaces, it actually rotates in the opposite direction because dominant effect is differential heating of residual air molecules on each side of a vane (https://en.wikipedia.org/
David’s talk comprised, principally, the geology of gold deposits on a world-wide scale by linking these historically with more recent knowledge of plate tectonics and the role of hydrothermal processes in concentrating gold from its trace element distribution in the earth’s crust into economically viable mineral deposits. Gold’s near-unique properties include its relative chemical inertness, combined with its high specific gravity and malleability to make the metal sought-after as a store of wealth. Some 50 per cent of all gold mined is utilised for that purpose, with 40% for jewellery and 10% for industrial uses such as, computers and mobile telephony. The current imbalance between newly-mined supply and physical demand is accounted for by recycling through scrappage. All the gold ever mined historically would occupy a space of 21 metres cubed. China is the world’s biggest producer and its second biggest consumer, after India. South African production has declined inexorably over the last four decades and there will be little production after 2030. Continue reading Gold is where you find it. Isn’t it? – David Cliff
The basic considerations when farming, which are topography, soil and rainfall, were discussed with particular reference to the Chilterns.
Simple mixed farming (few crops and a wide variety of animals), which had been practised for generations, gradually gave way to modern methods after the 1960s. Technical advances in plant and animal breeding, the development of weedkillers etc., but primarily the emergence of the Supermarkets and the demise of the Milk Marketing Board, were responsible for the changes. Today’s farming methods were discussed, together with farming support payments and environmental care inducements”.
Richard Jones gave the concluding part of a talk on Plate Tectonics – held over from the talk of 10th August 2016.