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AUDIENCE COMMENTS |
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An opportunity for the audience to have their say on In Our Time. |
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MAGNETISM
Terence Walls - magnetism
Welcome back IOT. What a pleasure to listen as names and events from history were kebabed on the skewer of magnetism, then grilled to perfection by the host. It did strike me that though the effects of magnetism may be well formulated, the causes (magnetic polarisation) and the means by which the causes bring about the effects (magnetic fields) are metaphors and not direct descriptions of reality. It is difficult to imagine how a single atom of iron (Fe) could present the necessary geometrical asymmetry to manifest magnetic polarisation. Two atoms, perhaps, could be polarised, but why Fe2 and not O2, for example? And, the 'magnetic field': what in reality could this be, other than a poetic device that diverts attention from the real question of how 'action at a distance' works? Now the Gravity programme should be interesting: mass (whatever that is) causes a distortion in space and time, or space/time, or space-time, or spacetime...
Bill Young - Download of latest IOT - Magnetism
When trying to download the MP3 file of IOT (programme on magnetism) the link simply opens RealPlayer and the programme begins - listen again rather then a download. Can someone sort this out please? Many thanks.
Chris Miller - Magnetism
Melvyn may have "felt like jelly" after an 8 week break, but what about us poor listeners? I've been suffering withdrawal symptoms, all I can say is welcome back! Regarding Newton's estimate (guess?)that magnetism follows an inverse cube law, this is approximately correct as long as the distance between the magnetic objects is substantially greater than the distances between their N and S poles (e.g. two 50mm bar magnets at a separation of 300mm). The reason for this is that magnetism DOES follow an inverse square law, but you have to allow for the effect of the opposing pole, giving a net force which is the DIFFERENCE between two inverse square effects. O-level maths demonstrates this is approximately proportional to an inverse cube. Hope this helps!
Thermodynamics & the Higgs Boson
In Thermodynamics John Gribbin said that the universe started in a disordered state, shown by the near-homogeneity of the background radiation. His idea seemed then to be modified by the others into the notion that the universe nearly died once before. So it must have begin in a highly ordered state. This was put more succinctly by Roger Penrose in the talk about the HIggs Boson, where he said that if you take the 2nd Law of Thermodynamics seriously, the very beginning of the universe must have been incredibly (infinitely?) ordered, and quite rightly he made this sound very eerie. It is. Could we return to this subject, or has it been dealt with under Religion? from Alan Marshfield
Bertie Coopersmith -- Magnetism
When it comes to science, nobody should expect to get to understand the subject matter at hand (magnetism in this case) from an IOT programme. What IOT is good at is restoring some historical and cultural balance to our technologically overloaded students. How well did this first IOT of the 2005 autumn do on this criterion? As often, disproportionate time was spent on ancient beginnings. It took nearly ten minutes to get up to Gilbert, then, after Descarte, Newton and Halley, over half an hour went by before Coulombe was dealt with and then in quick succession, Galvani, Volta, Oersted and Faraday. Maxwell, the man who finally brought electricity, magnetism and light together, escaped mention altogether. I give it 5 out of 10. Lord Bragg, in his succeeding newsletter, had this to say: "I think I should have asked what an inverse cube was, given that Newton arrived at it as his explanation for magnetism. Nothing Newton arrives at should be unexamined. Perhaps I felt too much of a coward or was looking at the clock and needed to press on to Faraday." Thanks for being so honest, Melvyn. I wish you'd really try to get your science panels together - or at least one or two could volunteer - to devote some time post-programme to clearing up just such 'mysteries' as 'inverse cube'. (Hint. Steer away from literary metaphore,and grind away at some notation instead.)
Vincent - Magnetism: could have done better...
Magnetism, what a fascinating subject. Just what is this force that can "act at a distance", sometimes attracts and at other times repels. I'm still none the wiser. The discussion of the early history of magnetic objects and their use in navigation was informative but I felt Melvyn spent too much time flirting and did not drive the conversation to a deeper description of the current scientific thought on the subject. I was hoping there would be particle physicist on the panel. Stephen Pumpfrey, John Heilbron and the evidently delectable Lisa Jardine were fine panelists. However the discussion lingered too long on the historical perspective I was hoping for a 'nuts and bolts' discussion illustrating the latest models of what magnetic force is, what mediates it, why it is related to the electric force, could it have links to the force of gravity etc. I welcome back 'In Our Time', still the best thing the BBC and Melvyn do. Looking forward the the rest of the series. "Whoarrr... Some archives on 'InOurTime' bye the way." Programes like 'InOurTime' justify the licence fee. Cheers BBC.
Sian Morgan/Magnetism
IN OUR TIME is the ultimate Broadcasting Magnetism, past, present and future.
Dave Wharton - Magnetism
Hi, I missed the end of the programme this week. Exellent stuff , but I have a question that occured to me . If you made a ball , say the size & smoothness of a snooker ball, how would it attract & repell?? It's not keeping me awake at night but it's starting to bother me :) Cheers Dave
Magnetism
Glad to see you back - good as ever, imho.
Michael Moody. Magnetism.
The programme should have been titled "The early history of magnetism". For how could you omit Maxwell's establishment of the laws of electromagnetism and Einstein's unification of electricity and magnetism within the framework of special relativity? That provided an answer to the question you were posing, what is magnetism? It's a relativistic effect of electricity -- perhaps the only relativistic effect detectable in ordinary life. You owe us a second programme on the subject.
Perception and the Senses
I have downloaded the MP3 version. What a remarkable programme. As a Psycholinguist I have always been fascinated by the subject. But recently, one of my daughters has received a cochlear implant - which makes me even more aware of the subject. As I do not know of any software to convert MP3 files into Text files, would it be possible to access the transcript of Perception and the Senses ? Welcome back Melvynn Bragg. and all the best for you new cycle. Kind Regards Jackie Griffith
Mark - Magnetism
Around 27 minutes Magnetic fields.... "children don't even play with magnets in schools" This is most emphatically NOT the case. Around 28 minutes... Melvyn: "I'm not looking forward to that piece of cake", a comment which I cannot imagine him making for a philosophical or artistic subject. Similar comments were made on the programme about mathematics last series (one that jarred was preferring a paragraph of textual description to a single line of algebra). Please, I do appreciate that he cannot know everything, but comments like this help to continue the perception that science is a harder and more obscure thing than the other topics being addressed. If a topic is new, let the expert guide you through it, the self-deprecation is not appropriate! It wouldn't be dreamed of it the topic was something like the work of an artist or philospher.
Thomas Kember Magnetism
The Chinese for compass is zhi nan zhen which translates literally as finger south needle. So, that means a finger that points to the south. If a compass points to the north, it can also be said to point to the south.
Andy Scott - Magnetism
Although I enjoyed this programme immensely I found the choice of discussants rather strange, three historians and no physicist. It may be for this reason that the programme missed out what I thing is the most interesting development in the story of magnetism. At the end of the 19th century the two great theories of classical physics were Newton's theory of gravity and Maxwell's theory of electromagnetism. It is generally stated that Einstein's work on relativity and quantum theory overturned classical physics but what is not usually mentioned is that Maxwell's theory was already a fully relativistic theory and was not overturned. Instead it turns out that magnetism, which only arises when electrical charges move, is actually a relativitistic effect. In this sense magnetism is an everyday proof that reletivity and not Newtonian mechanics is the correct theory.
Keith Martin - Magnetism
Magnetic forces may not remain quite as mysterious as implied at the end of this very interesting discussion. I believe Einstein showed (in his Theory of Special Relativity)that a magnetic force is just an electrical force experienced by an observer in a different (moving) frame of reference.
Jim Grozier - Magnetism
During the summer I did some research for a talk on the history of magnetism that I gave at a conference in August. According to my sources, it was NOT Coulomb who discovered the inverse-square law of magnetism, but John Michell, a less well-known English scientist who, apart producing from a law of magnetism, also apparently found time to become the Father of Seismology and to predict the existence of black holes, amongst other achievements. In order to measure magnetic forces, I understand he invented the torsion balance independently of, and some 35 years in advance of, Coulomb, and published his law in 1750. Am I wrong? I'd really like to know, as I am due to give the talk again on Saturday and would hate to be guilty of spreading mistruths!
About podcast
Hi, I'm just writing to suggest you should regain the mp3 download for this fabulous programme. I miss it a lot. Thank you, Rodrigo Ramos
Krysia Chambers Magnetism
The trailer you are using to promote magnetism implies that the medical uses of magnetism do not work. Can I point out that physiotherapists regularly pulsed magnetism to promote healing deep with tissue and joints and it is a proven medical aid.
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