[Post reconstructed after 25.10.07 hack]:
The strange object pictured above is a rather nice demonstration of the “field lines†around a bar magnet. It is not a great photo (all my fault), but the demo is great. The designers suspended the tiny bits of iron in oil, inside a sealed chamber, forming a block. There’s a little cylindrical hole through the centre of the block (but still outside the chamber) that allows you to put a bar magnet in. This makes for a demo far more exciting than any shake-it-up snow scene: You shake block and the iron filings are all over the oil in three dimensions, randomly arranged. You then insert the magnet. They slowly but determinedly arrange themselves into the familiar pattern, in three dimensions. It’s great. (Why didn’t they have these when I was growing up?! I might have gone into science… Oh, wait…)
I was looking around one of our demo labs last week for things to use to demonstrate some of the principal effects of magnetism. The above demonstration was one of the things I used, of course, and there were several others, from simple repelling and attracting of magnets with magnets to more dramatic things like shooting aluminium rings into the air using magnetic fields, and explaining the relevant principles and how they are used in various devices.
Why was I doing that? Well, it’s fun, for a start. It’s very sweet of Angella and Joe (two of our teaching lab professionals – see picture on right) to let me come into their carefully arranged demo lab spaces and play with things (Thanks!). But the reason I was doing it was for a new television show. Yes, another one. As I’ve said before in a previous post, I’m rather excited about the number of program makers who seem to be interested in rolling out new science programs of increasingly good quality (although there’s still exceptionally bad stuff still being newly made too), and I’m happy to help out when I can. (See a bunch of earlier posts on this, some listed below.)
So this time I got a call from another production company (Luke Ellis and Matt Hickey’s Workaholic Productions) making a pilot for the Discovery Network’s Science Channel. (I don’t know how much of this is sensitive, so I’ll not say the name of the proposed program just yet, nor give you content details.) The program makers are trying to unpack various concepts from magnetism, using a fun new approach/premise. I think I’ll end up watching this show myself, as it sounds like a lot of fun and I’m curious to see how all the elements (I’ll be one of several contributors, of course) come
together to tell the story of the science.
It was a lot of fun, and I hope their show gets picked up so that they can make more episodes, since it’s a great team of people who are keen to do a good job and let the science shine through while making a program that grabs the attention. I got that sense immediately from setting things up on the phone (talking with director/writer Luke Ellis and production assistant Chris Hutchings about the ideas and logistics before we got down to shooting), but I got a bit of a surprise when we were mid-shoot. (That’s Dylan O’Brien on camera picking out some closeups of me doing an experiment. Thanks to Luke for this and the other photo of me at work.)
The background goes as follows: It turned out that last week I was planning (but never got to it) on writing another blog post about the History Channel show “The Universe†to encourage you to watch some of the episodes, since (although it is not perfect – what show is?) I think that the show is worth supporting. (I’ve done a number of posts already, e.g. here.) I was going to particularly highlight the one entitled “Beyond the Big Bang†for how good a job they did on several aspects of the subject. (It’ll air again Nov 10/11.) They did a good job of explaining some of the key ideas surrounding the development of the foundations of the modern
precision cosmology we take for granted today. This goes back to the arguments over whether the Big Bang model or the Steady State model was correct. Usually, references to this discussion make the Steady State idea (of Bondi, Gold, and Hoyle – famously championed by Hoyle) seem like some sort of dodgy effort, and Fred Hoyle is often painted as a strange figure on the fringes. They did not do that in this program. The point is that the models were both viable candidates at the time, each with their strengths and weaknesses (from both the physics and philosophical perspectives of the day). There are good treatments in books (such as Simon Singh’s “Big Bang†– an excellent (relatively) recent book by the way), but this is the first program (or one of the few) that I’ve seen on television that get across the sense that – in the absence of the data that were yet to come – the discussions in the scientific community over the two ideas really helped sharpen the whole field of modern cosmology and build it into what it is today. Good science and good ideas came forth from people on both sides of the argument, bringing several fields of physics together in the context of astrophysics and cosmology (such as Hoyle’s pivotal idea on nucleosynthesis – explaining that most of the heavy elements we know are made in stars. As it transpired, the Big Bang is better supported by nucleosynthesis of the highly abundant lighter elements like helium – stellar processes don’t make them in the right quantities). Interestingly, some of the key ideas that underlie
the Steady State mechanism are showing up again in modern cosmology in a new guise, such as inflation, and eternal inflation. – Good ideas don’t always work exactly the way (or in the context) that they first arise, but they’re often good for something in the end.
I got off track there. What I was trying to say was that it turned out during the shoot (from my following up on a remark Luke made about a Princeton shoot they did) that this team that I was working with was the same team that made that Beyond the Big Bang program for the Universe series! So I actually got to tell them in person that they did a good job! They were amused to find that I’d been shooting material for new episodes in that series (with another production team) a stone’s throw away just a week or two before. It’s a small world after all.
Here’s to more collaborations between program makers and scientists in making good shows for all to see. (More discussion on that here.)
-cvj
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Regarding Super Nova observations, would it not be the creation of more iron ions within the sun’s plasma that is the cause of the sun reaching critical mass. Sun spots are caused by magnetic currents of electrical power that suppress the upward flow of heat from the nuclear furnace. Given enough creation of iron, the magnetic fields would be stronger and extend over the surface of the sun creating a nuclear pressure cooker….iron is the last element to be formed before a Super Nova happens. I am no expert but perhaps someone in the right area of research could comment on this. Cheers, Larry Stenger
I’m not sure what you mean by “bunkâ€. Your second statement does not contradict the first, in fact. That a store-bought bar magnet is not a perfect macroscopic dipole does not mean that the filings are not showing the patterns of field lines. What you’re saying is that perhaps a more refined version of the statement is that gradients in the field help them concentrate nicely in some areas more than others. But I think that you might be overstating the effect, since even in a perfect field, the symmetry is broken by the filings themselves. In fact, I’d guess that this is a more dominant effect than the one you mention. They are roughly all the same size, and they are paramagnetic, and so they would be very naturally pre-disposed to line up along the “field lines†and form a granular approximation to the underlying pattern where the scale of the granularity is set by their typical size, and the fact that they would not move too far from where you sprinkled them. I think that this scale is well above the scale that you’re talking about. I could be wrong, but I think the finite size of the filings is much more relevant.
Cheers,
-cvj
Back when I was a kid, they told us that the “iron filings†for which a better (non rusting) substitute is what one mostly obtains when one runs a magnet through soil (at least where I grew up), namely magnetite, lined up along the field lines of the magnet.
It was only after a lot of education that I realized that this was bunk. The field lines are symmetric. The magnetic material breaks the symmetry by making paths along which there are more field lines than average. The pattern we see is the breaking of the symmetry, not the field lines of a magnet with no iron filings.