Tides: From the Bay of Fundy to Black Holes
a public lecture by
Professor Don Kurtz
Jeremiah Horrocks Institute, the University of Central Lancashire, Preston, UK
Friday, 28 September 2018,
6:00-7:20 pm
Newton Lecture Theatre INB0114 in the Isaac Newton building, University of Lincoln
Book a place
Tides are mysterious. Why are there two tides per day? What causes Spring and Neap tides? What are Earth tides? Tides on other bodies in the solar system can lead to moons disintegrating – this is where the rings of Saturn come from. Stars have tides and there are now the amazing, new tidal “Heartbeat Stars”. Tides from some black holes would tear a person apart, so don’t get too close! This richly illustrated lecture looks at tides from the Earth to colliding Galaxies.
Don Kurtz was born in San Diego, California, to an American father and Canadian mother. He obtained his PhD in astronomy from the University of Texas at Austin in 1976, then spent 24 years in South Africa at the University of Cape Town, where he was Professor and Life Fellow. Don has dual British and American citizenship and has been Professor of Astrophysics at the University of Central Lancashire since 2001. He was recently vice-president of the Royal Astronomical Society and serves on many international committees. He is frequently invited to speak internationally to both professional astronomers and to the public. Don observes with some of the largest telescopes in the world, has over 2000 nights at the telescope, and nearly 500 professional publications. He is the discoverer of a class of pulsating, magnetic stars that are the most peculiar stars known. He is co-author of the fundamental textbook “Asteroseismology”. He is an outdoorsman and has travelled widely. Don enthusiastically gives many public lectures per year to diverse audiences all over the world on a wide range of topics. He is a regular guest on BBC Radio Lancashire and has appeared in prime time on the BBC’s “Stargazing Live” with Dara O’Briain, on the BBC One Show, and on the “Sky at Night” with Patrick Moore.
Header photo: New Brunswick Tourism
Distinguished Maths & Physics Public Lectures 
Letter from Mr Mervyn Whiting:
At the lecture last Thursday you alluded to those who “might be a little shy” to speak up at the question time. I am one of those people but I’d like you to know how great a privilege it is for me to be able to attend such beautifully presented lectures as those given by Prof. Don Kurtz for instance. I have been to most of the open lectures given by all departments over the past 10 years and particularly enjoy the physics ones.
I started at secondary school in 1941 and my education was blighted by
the war when we lost most of our able teachers to the war effort. On the plus
side the “blackout” did enable us to have incredible views of the heavens with sightings of the aurora, shooting stars, comets, etc. which fed my interest in the wonders of the universe.
My family have all had the advantage of higher education and one of my grandsons studied Astro physics at Oxford while his cousins became Drs. one studying medicine at Cambridge. Going to the lectures has enabled me to keep up to date with latest developments and have intelligent conversations with them. So many thanks to you and the University for giving us local residents the opportunity to attend such mind stretching lectures. Looking forward to the Charlotte Scott lecture which should prove very interesting.
Thanks once again. Mervyn Whiting
P.S. At 90 this year does that make me your oldest student?
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to Gerry Brown:
You are right. Nothing falling into a black hole stops at the boundary where the escape velocity equals the speed of light. The material falls in. Maybe this may help to think about the membrane idea: The Black Hole has a “radius”, known as the Schwarzschild radius after Karl Schwarzschild who first calculated this after Einstein published the general theory of relativity. It is the distance from the gravitation centre of the black hole at which the escape velocity equals the speed of light. For a non-rotating, spherically symmetric black hole, there is, therefore, a two dimensional “surface” with the Schwarzschild radius where the escape velocity is the speed of light. For the black hole itself, there is nothing at that surface; it is a mathematical construct that we use to characterise the black hole. What came up in the question session was my mention of Kip Thorne’s “membrane paradigm” for black holes that he published with Richard Price in 1988 in Scientific American. It is a way of thinking about black holes with a “membrane” that lies an infinitesimal distance above the Schwarzschild surface. Because of gravitational time dilation, this membrane may appear to an outside observer watching material fall towards a black hole. But for the black hole itself and the material falling in, nothing lies at the membrane surface. Unfortunately, Scientific American is not open access, and even this article from 30 years ago is not freely available. If you have access to a library with a subscription, you may enjoy reading the article. The idea has not caught on widely as a way to think about black holes, so it is not easy to find other discussions of it.
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Thank you Professor for your illuminating reply. It’s good to be able to converse with such an eminent scientist, not something that happens regularly in my everyday life!
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Thank-you for an excellent lecture, Professor Don Kurtz has a real easy way of getting ideas across and holding your interest. I travelled 50 miles to the lecture and it was well worth it.
Thanks to Lincoln University for arranging and holding these public lectures I will certainly try and get to the up and coming lectures as well.
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Love the public lectures at the university, can’t get enough of them. Extremely entertaining and educational in an accessible way. One thought I had regarding black holes is: how is it possible to think of a “surface” of a black hole as surely gravity acts continuously though decreasingly at distance and does not just stop at a boundary which a surface would be?
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An excellent and inspiring lecture. It has created a lot of discussion and a thirst to know more.
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Very interesting and entertaining. Carried a coherent thread across a very diverse range of topics.
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The lectures organised by the School of Mathematics and Physics are very good and very welcome. The last one by Professor Kurtz was superb. Some of the things he talked about I knew, some I knew at one time but had forgotten, and some things were completely new to me. Perfect!
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Brilliant lecture. Well worth coming from Nottingham to hear.
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Very engaging public lecture. Accessible to different targets and inclusive. I am not in this academic field and learned a lot. Many thanks.
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It was fantastic thank you! You just show me a bit of astrophysics can be understandable and fun. That one hour turn my life away, I know what I am gonna do now even I’m completely an outsider. Thank you again!
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Reblogged this on Astrophysics Group .
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Excellent Speaker, excellent content.
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