The curious incident

"The Curious Incident of the Dog in the Night-time" is a marvellous book by Mark Haddon. It is murder mystery book as done by a character with Asperger's Syndrome. He is obsessed with maths and physics.
Musing about his love for prime numbers, he says "Prime numbers are what is left when you have taken all the patterns away. I think prime numbers are like life. They are very logical but you could never work out the rules, even if you spent all your time thinking about them."
Later he discusses Occam's razor. This is a philosophical concept from several centuries ago. It states that you should always go for the simplest possible explanation of the evidence. Overcomplicated explanations are far less likely to be true. An example is what they did with the observed movement of the Sun. Yes, it looks as though it goes round the Earth, but that would mean that the planets would have to perform little spirals and loops in their orbits. Far simpler to have the Earth and all the planets going round the Sun.
Ican't recommend the book highly enough! It's brilliant. (parental advisory: lots of strong language when he reports what his parents and other adults say.)

The shortest day

Today's the shortest day of the year, the winter equinox. You'd expect that it is because sunrise is later than on any other day and sunset is earlier. This isn't quite true. For the next week, sunrise will get later and later, but sunset will also get later, by a little bit more, so overall the day length will increase. The reason is that whilst day length is a result of the tilt of the Earth's axis, day and night is caused by the rotation of the Earth around that axis. As the Earth travels a little further around the Sun, the Earth has to travel slightly more than 360 degrees to get back to the same point. This causes both sunrise and sunset to seem slightly later. After a week or so, the effect of the tilt of the Earth will have swamped thie effect.
It was put to me that this is why the mornings seem darker in January, but it's over by then anyway. And you'd be struggling to notice the effect against variations in weather due to cloud cover.

Revision blogs

The Lower Sixth can find archive postings on revision issues at http://www.brockbankrevision.blogspot.com/

The Upper Sixth will find similar at http://www.brockostressline.blogspot.com/

In both cases, you'll have to ratch around to find the stuff that applies to the topics that we have done this term.

Solar panels

We went to the RSPB's nature reserve at Leighton Moss in Lancashire. They have this display up about the solar panels on the roof. They have generated 8749 kWh of electricity in about six and a half years. At, say, 10 pence per kWh that's saved them over £800. I wonder how much they cost to install? The power is very low: 0.13kW on a bright day in December would do some low energy light bulbs. I'm also wondering how this system works. Does it mix with the mains electricity or does it run on a separate circuit?

A controversial book

I had my letter published in the Cumberland News suggesting that people read David MacKay's book "Sustainable Energy: Without Hot Air". It's his opinion so it's become a controversial book.

The letter next to mine suggested another book: "The Real Global Warming Disaster" by Christopher Booker. I have bought the book and am reading it. He is a climate change skeptic. ie he thinks that even if there is any global warming, it is not caused by humans. He does bring up some evidence that is hard to argue against. As far as I can tell, historically, rises in carbon dioxide actually follow rises in temperature, so it would be hard to say that carbon dioxide causes the rise.
At present, I am with the consensus blaming humans for global warming at the moment. But I've always believed that science is like a court case. You should listen to arguments from both sides and decide on the basis of the evidence. Hence it's always possible that new evidence might make me rethink my position. I'll let you know how the book goes.

Alan Guth Lecture

Alan Guth is a big name in astrophysics. He solved a problem to do with the Big Bang Theory. The problem was that the time since the Big Bang (roughly 15,000 million years) is not long enough for galaxies to form and for space to seem flat. Stars form when the gravitational forces between hydrogen atoms start to pull them inwards into large balls. Think about it - the gravitational attraction between atoms in piddly small so it should take forever. Then the stars have to be attracted together to form galaxies. What Guth proposed is called inflation. Early in its life, there was a massive expansion of the universe. That magnified the clumps of matter and let them pull in faster. It also stretched out the curved up ball of space-time so that it appeared flat.
Alan Guth has done this year's Isaac Newton lecture for the Institute of Physics. They have put the lecture up on the internet. I haven't had time to watch it yet, so of course it might boring but there's only one way to find out:
http://www.iop.org/activity/awards/International%20Award/newton09/page_37514.html

Lorn!

Fans of natural logarithms (Ln) will realise that they now seem to have been rebranded as "lorns". I think we've agreed on that spelling instead of "Lawn", which is a suburb of Swindon. Well, at least it's better than the class who used to refer to it as the "in" button on the calculator. So imagine my pleasure to discover that my Scottish holiday was to the region of Lorn. I want to be MacDougall of Lorn when I grow up. (NB1 some of you might take this as evidence that it will be a long time before I do grow up) (NB2 the carving is in the marvellous church of St Conan - not the barbarian- which is very close to the Ben Cruachan pumped storage facility at Loch Awe)
Logarithms (ordinary Log on a calculator) are a great way of working out how to express any number to the power of 10. I'm not fond of the number 3. To avoid using it, I can do Log3, which is 0.477. So instead of saying 3, I can just say "10 to the power 0.477" instead, because they mean the same thing.
Natural logarithms are based on the number "e", which is another fantastic irrational number like pi. It helps you to work out a way to write any number as a power of e. We use it a lot in physics to analyse exponential decay in radioactivity and in capacitors. It helps us turn curved graphs into straight lines. (Now Ln3 = 1.099, so I could avoid saying 3 by calling it "e to the power 1.099" instead.)

Solar panels - at last, some data!

The RSPB nature reserve at Leighton Moss near Lancaster has had 10 solar panels on the roof for the last 6 and 1/2 years. In that time, it has generated 8749 kWh of electricity, according to the display. So that's about 1300 kWh per year. Which could be worth at least £100 of electricity per year.

I wonder how much they cost to install?






The low power rating also raises questions, because 0.13kW would only run light bulbs or TV sets - things that aren't designed to produce heat. However, if the panels just add to the total electricity coming into the house, meaning that less is taken from the grid, then perhaps they will provide an interesting alternative.

Wigton church stained glass

Tomorrow Melvyn Bragg is doing a talk about the new stained glass windows that he commissioned for St Mary's. It's part of the festivities for the switching on of the Christmas lights. If you haven't seen them, yet you've missed out. They must be the best modern stained glass in the country, in the opinion of this observer. They were designed by Brian Campbell, who used to teach art at school.

The window in the picture has views of school and other recognisable buildings in Wigton. But it also rectifies a particular physics problem: it has the rainbow colours in the correct order.

The second picture here shows the older stained glass above the altar. There is also a rainbow on it. The colours are in the WRONG ORDER! And I have to look at it every week! I'd like to think that this is evidence that physics education in Wigton has improved in the last century!

Horizon tonight

Horizon tonight on BBC2 9pm to 10pm will be about quantum physics. You should watch it.

It will be on the BBC iplayer all week.

My trip to London

I was invited to represent the school at this symposium at Imperial College. Professor Harry Elliot was a student at this school in the 1930s. His name appears 3 times on the honours board in the library.

I got to find out about his start in cosmic ray research and how he then built a whole research team at Imperial College, London. He became one of the key people in European space research, sitting on committees that planned and carried out scientific space missions. I discovered that he had a key involvement in several things that I have taught.

He was responsible for the quenching agent in a Geiger Muller tube.

He was involved in planning the mission that produced the gamma ray photograph of the Milky Way that I use with year 10.

The number of professors in attendance shows that he commanded enormous respect.

I'm deeply grateful to Professor Steve Scwartz and Professor Andre Balogh for inviting me.

Try this link for further details of their research programme

http://www.sp.ph.ic.ac.uk/~balogh/history.htm

Melvyn Bragg's book about science

Lord Bragg of Wigton, Melvyn Bragg, produced a book about science 10 years ago. It is basically the transcipt of a radio series he did on famous scientists. He interviewed a lot of interesting current scientists. It is an excellent study of the way in which science works. It's called "On Giants' Shoulders" (based on a quotation from Sir Isaac Newton) and there is a copy to borrow in Wigton Town Library.

I was particularly interested in what he said in the introduction to the book: "Although I greatly enjoyed maths at school, and at one stage wanted to take it in the sixth form, I was never enticed into physics. This is not to blame the teachers, for, soon after World War II and in a small Northern grammar school, teachers, especially it seemed in physics, came and went at some speed." That's our school! Hopefully he'd be enticed into physics if he were here now.

This is a great book and you ought to read it. I'd also recommend looking at the new stained glass windows in the church installed by Melvyn Bragg to spot all the amazing little Wigton details.

My letter was published

My letter about David MacKay's book was published in full in The Cumberland News last Friday (6 November). It's not on the web version, so you'll have to have bought a copy but in due course I will put a copy up in the lab!

Searching for uranium in Dumfries

I went to A spot below Criffel in Dumfries to look for uranium salts in the rocks. Geologists found the salts at Southwick cliffs in the 1960s. I found a paper about it on the Internet. The Geiger counter reached 3 times the normal background, but it was terribly overgrown and I was not able to locate the original excavations or those of 1990. This is what it looks like:

My trip to Schiehallion

Horizon BBC 2 Tuesday 3 November

Horizon this week is about black holes. You should watch it.

BBC2 Tuesday 3 Nov at 9pm for an hour. If you miss it, it'll be on the BBC i-player for a week.

Successes and failures

Well, The Cumberland News didn't print my letter. Oh well.

However, we climbed Schiehallion yesterday - photos next week when I've got broadband again. There's a large plaque at the bottom commemorating Nevill Maskelyne's gravity experiment in 1774. I've collected some rocks so we can check the mass of the mountain by a density and map method in the lab. The cloud clearer when we were on the summit and we could see half of Scotland.

The nearest village has one of the oldest trees in Europe and claims to be the birthplace of Pontius Pilate. How weird.

The musical stones in church last Thursday were entertaining. They have been made up into a xylophone and were nowhere near as big as I'd expected. I've seen photos of Sigur Ros playing a much bigger stone xylophone. Still, I now want to know why you can get a note out of the metamorphosed hornfels but not the original slate country rock.

Letter to The Cumberland News

If you trawl through the older posts, you'll notice that I am a big fan of Professor David MacKay's book Sustainable Energy: Without the Hot Air. He has since been appointed as a government advisor. I'm pleased because he believes in a no-nonsense approach to working things out. I'm in favour of numbers. They make a debate more precise. He's good at providing figures. I've checked a lot of my own consumption figures to test his claims.

In the farming supplement of the The Cumberland News 16 October 2009, Austen Davies lays into Professor MacKay in his View from the Trough column. The article starts really well - I agree with a lot of the commentary. Nor does it bother me that Austen Davies is vehemently against wind farms. I'm not sure where I stand on that issue. I love the mountains and the way I read the book is that Mackay thinks too much land would be needed so it's not really feasible.

But I don't like a level of debate that descends to personal attacks. "Wildly staring eyes of Vulcan-looking Professor David MacKay". So I've written a letter in defence of the book! Let's see if it gets published. Now is this citizenship?

Skiddaw musical stones performance

Further to yesterday's post, it is at 6pm on Thursday. Word on the street is that it will be packed out.

Skiddaw musical stones

On Thursday, the local primary schools will be playing the Skiddaw musical stones in Wigton parish church. It is 6pm for the final performance.

The stones are normally kept in Keswick museum and I think that they are like a giant xylophone.

There is a bridge in the valley between Blencathra and Skiddaw, which has, according to my guidebook, similar slabs. It said that if you tap them gently with a hammer, the slabs should ring. Trouble is, they have been cemented in, which is damping the vibrations.

The physics goes like this: When you hammer them, a sound wave travels through the stone. It travels very fast in the solid because the atoms are close and joined. It cannot travel fast in the air, so when the vibration hits the end of the stone, very little escapes into the air and the rest is reflected. If the dimensions are such that the reflected waves are in phase with the outgoing waves, then a standing wave is set up and that is what you hear. Damping removes energy from the vibrations.

Searching for radon gas

I got this plastic in the summer called Tastrak. It is supposed to get scarred by alpha particles when radon gas is released from rocks underground. It turns out that the limestone rocks around Sandale and Caldbeck are supposed to be medium bad for radon, so I gave a piece to someone I knew to test it. Nothing!

So last Saturday I hid a piece at Sandale Quarry. I'll collect it in a couple of weeks. You need a microscope to see the marks.

Electric field lines

I have used a petri dish of sunflower oil with semolina floating in it to see the field lines for an electric field. It's similar to doing the iron filings experiment for magnetic fields. I made the metal contacts from a coat hanger and connected it up to 3000 Volts. I projected the result onto the board and you can see the semolina lining up between the contacts. The parallel lines show a uniform field, which will have a constant field strength throughout.

Don't look back into the sun

This week I've started looking for sunspots. You musn't look at the sun directly. You'll seriously damage your retina. To look at it, block off one side of the binoculars and shine the sunlight through the other side onto a piece of paper. The second picture shows the image of the sun thus obtained. Sunspots are slightly colder areas on the surface of the sun. There are none in view at the moment. The sun rotates on its axis every 25 days. Maybe in a couple of weeks ...

Sunspot activity goes in 11 year cycles. I thought it was supposed to be good at the moment, but maybe I've picked a bad time to start.

To undefined and beyond...

OK, so maths have rebranded infinity as undefined. I think this gets us back to the essential difference between physics and maths - that physics is measurable. So in physics, we need to be clear that infinity will mean something different. In the case of infinite resistance, what we actually mean is that it is UNMEASURABLY BIG. Remember, maths like their perfect fractions like 2/7. That won't do in physics. We use decimal fractions to show the precision of the measurement. It DOES matter whether you write it down as 0.29, 0.286 or 0.2857. So there.

My geiger counter

Sounds rather grand, "my geiger counter". Actually, it's a datalogger with a geiger muller tube. It's portable so I took it on tour in the summer.

The watch belonged to my father-in-law. He bought it in 1951. In those days the luminous paint on the hands was made of a radioactive material. The final photo showa the geiger counter reading. The "safe" background reading that I took was less than 1 count per second. You can judge for yourself how dangerous a watch like this might be.

Ciamar a tha thu?

In honour of languages day, here's another highlight of my trip to Scotland. This village is the only place in the UK to have a chemical element named after it - strontium. The element was discovered nearby about 200 years ago. It is of interest to physicists because the fallout from nuclear explosions contains a lot of the radioactive isotope strontium-90. This is a problem because the body prefers to take this in place of calcium for bones. It has a half life of about 28 years so it's not good for health. It was a major problem after the Chernobyl accident.

All place names in the Highlands are anglicised versions of Gaelic names. I've been trying to learn to pronounce Gaelic. The title of this piece means "How are you?" You can reply "Tha gu math, tapadh leat" - Fine thank you.

Why do some physicists get really annoyed about string theory?

Last week my network had some bitter emails on from physics teachers complaining about string theory. What makes them so angry?

String theory comes from this idea: If a room has 3-dimensions, a flat piece of paper has two dimensions and a line has one dimension, then a point (a spot) will have no dimensions. This makes the maths difficult when we start dealing with atoms and other particles, which are modelled as being points. Inverse proportionality doesn't work because 1/0 comes out as infinity. In black hole, the problem is called a singularity.

So someone suggested that if we said that particles were really one-dimensional vibrating strings, then it would all be all right (except that it would mean that the Universe would be in 11-dimensions). This is all good except that for a theory to be accepted in physics, it has to make predictions that can be tested by experiment. This is difficult for string theory. My email correspondents are angry because a lot of research money is spent on string theory and yet it might not even be real physics. However, some of the greatest brains in modern physics are on board. One of them, Brian Greene, wrote an excellent book on string theory. It's in the school library.

Why is the sky blue?

When rays from The Sun enter the atmosphere, the light is a mixture of all the colours of the spectrum. Particles in the air scatter certain colours sideways. The smaller the wavelength, the greater the scattering, so blue is scattered most. Having been knocked sideways, it is this light that gives the sky its colour.

At sunset, when the light comes in at an angle, the light has to pass more particles to reach us. Thus more colours are scattered, leaving orange and red to reach us.

I did an experiment to show this using a projector and a bowl of milk. I introduced milk in small amounts to represent the scattering particles. The photograph shows what happened.

The search for a sun dog

What you're looking at in these two photographs is the layer of thin, high cloud. It's called cirrus if it is small, wispy cloud, and cirrostratus if it coalesces to form a layer.

At certain times, you can get a circular rainbow around The Sun as its light is refracted through ice particles in these high clouds. Sometimes you get part of it like an upside down rainbow. I'll put a newspaper photo of this up on the wall in C11.

However, sometimes, the effect is so intense that you get two fake suns, one on each side of The Sun. These are called sun dogs. I've never seen one but it is supposed to happen up to once a week in these lattitudes. Apparently the best conditions are when The Sun is low in the sky. The hunt is on.

Go to http://en.wikipedia.org/wiki/Sun_dog for details and photos.

The book has arrived!

Sustainable Energy: Without the hot air by David J C MacKay is now in the school library. You really ought to read it!

See earlier post for why this book is so important.

A kid asked a question at Jodrell Bank

I was stood looking through the fence at the telescope when a child turned up with his dad. He asked his dad "How do they make it turn round?". His dad said "It's got wheels." The child said "I can see that, but how do they get the wheels to turn on something so heavy?"

My problem as a physicist is that I take to many things forgranted. I hadn't thought about the technical problem of producing a mechanism to turn such a heavy piece of equipment. It's obvious that it turns, because it does! I tend to get stuck in "It's like that, and that's the way it is" thinking. The best physics don't ignore it because it works. They ask howit works and why it works.

Jodrell Bank

In August, we went to Jodrell Bank. It is a radio telescope connected to Manchester University. If you are headed south on the M6, it is worth a visit - about 5 miles off the motorway just past Manchester. It only cost £2 to get in. There's a lot to see, but I'd advise a nice day because a lot of it is outside.

The idea is that stars produce waves across the whole electromagnetic spectrum, and that what we can actually see is only the tip of the ice berg. Many types of electromagnetic wave cannot get through the atmosphere, but radio waves can.

The opportunity to work at Jodrell Bank would be a good reason to look at physics at Manchester University.

You can read more about their research at http://www.jodrellbank.manchester.ac.uk/research/

You must read this book

It sounds boring, but Sustainable Energy: Without the Hot Air by David J C MacKay is a must-read. In it, he assesses various possible futures for energy supply in the UK after fossil fuels have finished. The key thing that makes this book stand out is that he uses simple methods to calculate the available energy resources in each sector.

So whether you think nuclear or wind is the future, he comes up with the numbers.

He is a Professor in the Physics Department at Cambridge University. He tries not to state his preferred future option, but I think you may detect slight bias in places!

I ordered a copy from Wigton Library (they had to get a copy sent up from Kendal!) but it will be in the school library soon. However, if you want it for free, you can download it from www.withouthotair.com

It will make you a better physicist.

Schiehallion

The other important sighting from the top of Ben Nevis was a cone shaped mountain to the south east called Schiehallion. In some ways, it is the holy mountain of physics.

In 1774, the Astronomer Royal Nevil Maskelyne travelled to Scotland and used Schiehallion in an experiment to find the mass of the Earth.

What he did was to hang a pendulum. The Earth attracts the pendulum downwards but the mountain attracts the pendulum sideways.

By measuring the angle of dangle, he was able to use Newton's Law of Gravitation to calculate the mass of the Earth, providing he knew the mass of the mountain.

That's why he chose Schiehallion. As you can see, it has a very regular shape meaning its volume is easily calculated. It is isolated so other mountains have little effect. Using the density of the rocks and the volume, he could calculate the mass.

My two unanswered questions are these:

• The angle of dangle was very small, much less than a degree. How did he measure it?


• How did he know which direction was vertical? You usually hang a pendulum (plumb line) to work that out.
  

Physics on the top of Ben Nevis

I went to the top of Ben Nevis in the holidays. At the top there is a ruined weather station with this plaque honouring a Nobel Prize for physics.

It was awarded to CTR Wilson for his invention of the cloud chamber, a device for allowing you to see the invisible paths of radioactivity by getting vapour trails to condense where they have created ionised air molecules along the way. He was inspired to do this by his observations of clouds from the top of Ben Nevis.