Archive for December, 2011

Spectrum View

December 25, 2011
Scale on a flute

A spectrogram or sonogram. It shows the frequencies present in a sound. In this graph a flute is playing a rising and a falling scale over a single octave. Click for larger image

Spectrum View: Wow! How can this app exist on a phone? The app digitizes sound from the microphone, computes the frequency spectrum about 100 times a second, and displays a graph showing how the spectrum changes with time. This particular app is free, which means I shouldn’t complain. And I’m not. But since the app doesn’t provide any way to export the data, it is really nothing more than a fascinating toy. But I think it is fascinating enough to earn a place in my ‘Science’ folder. While looking around I notice that there are several semi-professional apps that will export spectra, and function as oscilloscopes as well. I will review them when I pluck up the courage to blow £15 on an app!

A constant note (F) on a flute.

A constant note (F) on a flute.

Infinities in nature 2: SUSY, Squarks and Sleptons are the answer!

December 23, 2011

David Bailin, my former tutor at Sussex University, left some detailed comments on my article on the idea that there are infinities in nature. His comments deserve a wider audience, particularly Part 2 on super symmetry and the Higgs. So here they are:

The infinity in QED, and other quantum field theories, derives from a short-distance cut-off which should be zero, IF there is no new physics at all. We know that QED does not include quantum gravitational effects, and the electron surely interacts with gravity. So at the very least there should be a cut-off at the Planck length, corresponding to an energy scale of 10^{19} GeV. The observed (finite) mass is then the sum of the bare mass and the finite quantum radiative correction, so evidently the bare mass is finite too. I share your (and Dirac’s) view that infinity in a phsical theory is a sign that something is wrong, i.e. that there is other relevant, generally new, physics.

Further, the radiative correction to the electron’s mass, and in general any fermion’s, depends only logarithmically on the cut-off. Even if the cut-off is as large as the Planck scale, the radiative correction is of the same order of magnitude as the observed mass, and so, therefore, is the bare mass.

Now suppose that the Higgs boson is indeed discovered at the LHC, with a mass of order 125 Gev/c^2. Unlike a fermion, the radiative correction to the mass(-squared) of a SCALAR particle is proportional to the cut-off (squared). In this case then, if the cut-off is of order the Planck scale, the bare mass(-squared) must also be of this order; in fact the bare mass-squared and the radiative correction have to cancel to one part in 10^{34}! Many people, including me, think that this is implausible, although there is no theoretical reason why it should not be thus. It is an aesthetic objection called the “fine-tuning problem”. The only known way to evade it is SUPERSYMMETRY (SUSY), which requires all of the known particles to have partners with the opposite statistics: fermions have (scalar) boson partners (selectrons, squarks, sleptons), and bosons have fermionic partners (photinos, gluinos, Winos, Zinos, Higgsinos). None have yet been observed, so the symmetry cannot be exact. However, the breaking cannot be at too high a scale. Otherwise it will not solve the fine tuning problem. This is why we expect SUSY to be discovered soon. It is another reason why the discovery of the Higgs would be of such importance. It would be the first known fundamental scalar particle, and would show that there is no obstruction in principle to the existence of the susy scalar particles.

Well, I think those are the best new particle names I have come across in years. I can’t wait until they discover a Wino in the LHC :-).

Happy Christmas

Are there infinities in nature?

December 20, 2011
Infinity

Infinity is a mathematical quantity - no physical quantity is ever infinite.

The concept of infinity is endlessly fascinating. For philosophers, for mathematicians and of course children. We have all wondered about how any number can be infinite, because we can always imagine making a larger number: infinity plus one. The concept of infinity is also discussed in the context of the physical sciences. However, frequently people neglect to mention that there are no infinite quantities in physics. None? Well, I don’t think so. I think that infinity is fundamentally a mathematical concept and in reality something else always happens that interferes with the extremity of physics that would happen near an infinite quantity of anything.

Are you sure? Well ‘No’.

I agree that in the physical sciences, the word infinity is often used. I remember being taught at school that when one’s eyes were relaxed they were ‘focussed on infinity’. I wondered about that phrase for a long time, but in the end I concluded it was just poetry. It means one’s eyes were set so that parallel light would be focussed onto one’s retina. If the light had indeed come from infinity,  it would – of course – not have reached us yet.

What about the singularity around an electron?  At Sussex University, Dr David Bailin taught me that a ‘bare’ electron would have infinite mass and infinite electrical charge. I was told that the particle that we observe and call ‘an electron’  is actually a hypothetical ‘bare electron’ plus its ‘re-normalised cloud of virtual electrons and positrons’. This cloud is created by the intense electric field around the infinite electrical charge. What that means is that in reality we never observe an electron to have infinite mass, but theoretical physicists imagine a real electron as being composed of a hypothetical singular particle plus another phenomenon that hides the singularity. The upshot of this is that a ‘bare electron’ is a mathematical concept – not a physical one. When we look at electrons we never observe an infinite property.

Similarly, it is populalry stated that a black hole is a ‘gravitational singularity’ – an infinitely strong peak of gravitational intensity. But of course we have no observations on this and based on everything we know, we would expect that as the field intensity increased – ‘something’ would happen. Currently, we have no idea what that ‘something’ is. But there is certainly no experimental evidence that a gravitational singularity actually exists. The intensity can reach any amazingly large number. It can reach an intensity which is so alarming that it takes my breath away. But as long as a number can be associated with it – it is not infinite. I am prepared to be ‘boggled’ by large numbers but not ‘baffled’ by an unphysical concept.

What about the Big Bang? At the time of the Big Bang – something is supposed to have exploded for reasons we have not yet figured out. Amazingly it seems that the vast universe hat we observe, and all the energy in it, was once packed closely together in the space occupied by a proton. So the universe was once unimaginably hot and dense. Do I mean infinitely hot and dense? No, not infinitely so, just orders of magnitude beyond any regular conception of temperature or density.

What about the Universe? Well there are many different conceptions of the Universe – and we have data from the cosmic microwave background indicating that the furthest structures that we can see are at most around 40 billion light years distant. Beyond that there is certainly something else, but we just don’t know what. But surely, I hear you ask, one can always keep going? Well actually, we just don’t know! In some conceptions one can, and in others one can’t. But there is no reason to suppose that the Universe is infinite – only that it is even more uncomfortably large than we previously conceived.

So is infinity unphysical? Well I think so. I would love to hear of an example of an infinite quantity, but actually I just don’t think that an infinite ‘anything’ makes any sense at all. And as a measurement scientist I would be very interested to know of the uncertainty of measurement of an infinite quantity: infinity plus or minus what?



Durban is not so far from the Cape of Good Hope

December 16, 2011
Rainbow at the Cape of Good Hope

Rainbow at the Cape of Good Hope: not so far from Durban. Picture Courtesy of Panoramia(?) from Google Maps

Decent folk who hope that our leaders will institute collective international action to address the carbon crisis are used to disappointment. So the inconclusive outcome of the Durban summit and news of Canada’s exit from the Kyoto protocol will cause sadness, but no surprise. And as the science becomes clearer, so the extent of political manoevering and obfuscation increases as politicians seek to justify why they have not yet acted. And although there is really very little that I can add to raise anyone’s spirits, I note wryly that Durban is not all that far from the Cape of Good Hope. And I think a little hope is still allowed.

The nations of the Earth can only do what it is economically and politically possible for them to do. And no more. In the same way that some natural processes are energetically possible, but are forbidden by the second law of thermodynamics, so there are some political changes which cannot happen, even though we might desire them. So I feel that there is no point in ‘wishing’ that politicians would do what is environmentally called for – this is just to subject oneself to perpetual depression. Canada’s exit from the Kyoto protocol demonstrates this explicitly. It is politically impossible for a massively carbon-polluting democracy like Canada to just pay out billions of dollars and receive no ‘benefit’. And similarly the USA, China, and India are just not ready or able to act.

But I believe that what is possible is changing – and expanding – daily. The very concept of the peoples of the Earth acting collectively is now conceivable and not crazy. The idea that there could be a shared environmental hazard is now accepted. For countries that are just getting used to the idea that actively planning to destroy all life in other countries might not be such a smart thing, we are doing OK. Techniques and methods  for measuring and counting carbon emissions are still in their infancy. And there are thorny problems such as who ‘owns’ the emissions from ships or planes, or the goods they carry? Collectively we have moved a long way in recent decades. And the time for real action is probably now less than a decade or two away.

As consciousness changes,  and as the climate change signal emerges ever more clearly from the noise of cyclic variability, I feel sure that countries will eventually act. Of course each year we wait the task becomes harder, but I feel that we will eventually get our act together. At least I hope so.


Carbon and Debt

December 14, 2011
Are there parallels between the 'debt crisis and the carbon emissions crisis?

Are there parallels between the 'debt crisis and the carbon emissions crisis?

I have been struck recently by profound similarities between the debt crisis and the carbon crisis. Here are seven points: see what you think:

  • Both these crises arise from a choice to consume now and pay later.  With the debt issue, this is true both at a personal and a national level. Politicians have shied away from making people aware of the true cost of their policies for fear on unpopularity. Similarly, because of the potential unpopularity of the policies required to address carbon emissions, politicians have held back from policies that would dramatically cut carbon emissions.
  • Both these crises require us to address intergenerational morality.  In the same way that it is unfair to spend money now and expect our children to pay it back, so it is unfair to emit carbon now, and expect our children to deal with the consequences.
  • Both these crises require international solutions.  National politicians have failed us: they are unable to resist spending and borrowing more in order to stay popular. And so the Eurozone have now called for central oversight of national budgets to make sure countries do not surreptitiously borrow too much. Similarly, the nations of the world require external limits to be imposed upon them. Only in this way can politicians tell their people: ‘its not our fault’.
  • Neither of these crises will ever be ‘solved’ – they are perpetual struggles not isolated events.  Recent events in Europe may make it seem that a particular path to a solution has been found. But it hasn’t. The forces which drove Europe into its difficulties and which created spectacular indebtedness in the UK are still all in play. Similarly, the outcome of the Durban conference is neither a cause for celebration or depression: it is just another step on the path, and we really don’t know what lies ahead.
  • Accounting is difficult and dull and boring. But essential. This has been true of financial accounting for many years, and it will be equally true of carbon accounting when the concept becomes established. But what appears to be a constraint on freedoms or our growth, is simply a way of staying honest.
  • Spending money you have borrowed is like burning carbon: it makes us feel good. Building a hospital we can’t afford brings benefits and so does burning carbon – we get improved lifestyles today – and much cheaper than the sustainable lifestyles we might aspire to. But eventually we will have to pay the cost. In financial terms this can involve reduced incomes which will the harm people’s health as well as their wealth. In carbon terms, we really don’t know what the costs will be, or who will be required to pay them.
  • Paying back debt is really hard: if you have ever had to pay back any significant amount of debt, then you know how hard it is. This is as true for nations as it is for people – with additional unfairness in that the people who borrowed the money and benefitted are not the people who have to pay it back. If we are to ever get back to some kind of carbon neutral economy then it will involve real pain as we wean ourselves off carbon emitting technologies. Real pain – and most probably real reductions in quality of life.

I could go on because I think the parallels are quite deep, but I think I have made the point. However, I do just want to add that in both cases, there is no need to despair. The world is very beautiful, and very resilient. And we have each other. If we can learn a lesson, and teach our children, then we can still make things better than they otherwise would have been.

What could possibly go wrong?

December 12, 2011
The recovered tail fin of flight AF447. The fully-functioning aircraft was flown into the sea killing all on board. There are lessons to learned for other safety critical control systems. Picture Courtesy of Wikipedia

The recovered tail fin of flight AF447. The fully-functioning aircraft was flown into the sea killing all on board. There are lessons to be learned for other safety-critical control systems. Picture courtesy of Wikipedia

On June 1st 2009, a well-trained crew flew a fully-functioning state-of-the-art aircraft into the atlantic ocean, killing all on board. It took less than 5 minutes to go from cruising at altitude to crashing into the sea. At enormous expense and against all odds, the French government recovered the flight voice and data recorders and now we know what happened. As one reads the account of the last few minutes of the flight it is difficult to fathom how the pilots could behave as they did. But the essential element appears to have been tragically simple – the crew were confused.

The confusion appears to have arisen at the interface between automatic and manual control of the aeroplane. As the crew took manual control, they didn’t know which instruments to believe and so – time after time – and in the face of the repeated warnings – the crew made exactly the wrong decisions. This is a tragedy in itself, but I think there is a wider lesson to be learned. Imagine, if you will, that the crew were not flying an aeroplane but running a nuclear power station.

The level of safety criticality of systems for nuclear power stations and aeroplanes, while not the same, is of the same order. People exhaustively plan out all possible routes to catastrophe, and then block these routes by a combination of methods involving hardware, software and procedural training. However, the lesson of Flight AF447 is that there is always a risk of catastrophe, even with well-trained highly-motivated crew and perfectly functional hardware. If controllers are confused, then they can make the wrong decisions.

One solution is to have control systems for aircraft and power stations which are driven by software with no human override. This would avoid mistakes arising from confusion and panic. It would also be cheaper since there would be less need for highly trained staff. What could possibly go wrong?

Publishers should sell books – not exams.

December 10, 2011
An Exam

Is this (a) an examination or (b) a source of profit for Pearson publishing? Discuss

One of the challenges of bringing up teenage children is the task of relating one’s own educational experience to theirs. It’s hard, because things have changed so much. At the school attended by one of my children the teachers are obsessed with teaching children how to get marks in exams: it is an understandable obsession, but it is soul-destroying for children. IMHO teachers should teach children about their subject.  For all its faults – and there were many – my time at school was packed with ‘learning stuff’. Loads and loads of ‘stuff’! But that is not how things are in many schools these days.

The Telegraphs’s exposé of Edexcel’s practices – corrupt according to Steven Twigg MP – is damning. But this is not news to teachers.

During an Edexcel geography GCSE training course in Birmingham, the reporter asked Miss Warren why she should pick the exam board. Miss Warren replied, “It’s very, very traditional, Edexcel, and also, as these two will tell you [indicating to two teachers sitting nearby] you don’t have to teach a lot, do you?

No, there’s certainly a lot less content,” one teacher then said.

Miss Warren added: “Yes, in fact there’s so little we don’t know how we got it through [the exam regulators]. And I’m deadly serious about that. When I looked at it I thought, ‘how is this ever going to get through?’

As the teachers around Miss Warren agreed with her assessment of the Edexcel exam, she concluded: “It’s a lot less, it’s a lot smaller, and that’s why a lot of people came to us.

And the worm that has brought about these changes? The Telegraph pulls no punches:

Edexcel was previously a charity until it was acquired by Pearson, a multinational media company, in 2005. Its profits have since risen 10-fold and its managing director is one of the best-paid individuals in education. The company made profits of more than £60 million last year – compared with less than £5 million in 2003. A spokesman for Pearson said: “We do not see a conflict between our education goals and our commercial success. We believe they are mutually reinforcing. Our commitment to upholding standards and our ability to develop rigorous qualifications are fuelled by our financial performance.”

But sadly The Telegraph’s story -reported by the BBC as another morally corrupt scheme for teaching teachers how to get children to pass exams. – is no surprise. I have written about it before:

The solution is simple:

  • The UK needs one exam board which would be run by civil servants.
  • Exams should not be set, as they are now, by companies owned by large publishing corporations who will benefit financially if more students pass their exams.
  • Teachers should have no idea what will come up on the exam: they should teach ‘knowledge’ and then students who understand best will do best.
  • The definition of A and A* should be changed and defined not by the mark achieved but should indicate a percentile of the exam population. So for example an A* should indicate that a candidate is in (say) the top 1% of the exam group. An A would indicate (say) the top 5%. Marks B and C below this can be defined differently, and in this way grade inflation is avoided, but students who work hard can do better.

This is not rocket science – but we need to abandon the idea that ‘the market’ has any place in setting exams. Publishers should sell books – not exams. And certainly not set the exams and the books which will help students pass.

Atom in a box

December 8, 2011
Visualisation of the 4 p orbital in hydrogen.

Visualisation of the 4 p orbital in hydrogen.

Did I mention I had a new iPhone? Well the other day I found out that one my favourite pieces of software was available now as an app: Atom in a Box. The app is simple – it shows the shapes of the electron orbitals in a hydrogen atom. And that’s all!

What I love about it is that it works at multiple levels. To a student learning about physics they can appreciate that these are just the shapes of the orbitals. They can look at the orbitals from all angles and see the shapes of the lobes. When I was a student I had to try to imagine what these things looked like!

But if they want to delve a bit deeper,  application shows the mathematical function that generates the orbitals. And so if you are interested you can make connections between the physical form of the function and its mathematical representation. It also uses colour cycling to show the phase of the wave function, an especially difficult-to-describe aspect of complex functions.

So if only to remind yourself of what these wave functions look like, IMHO this is worth 69p of anybody’s money. (App Store Link)

TOP TIP: To take a picture of the screen hold down the HOME and the SLEEP buttons at the same time. An image of the screen will appear in your camera roll.

When demonstrations go wrong: video evidence

December 1, 2011

I mentioned the other day that I gave a talk at TEDx Teddington, and video evidence has now emerged. Happily the 16 minute movie has been gracefully and mercifully edited so that several minutes (which felt like hours!) of faffing around on stage has been lost.

Seeing it now I feel that my first conclusions were right

  • Live demonstrations trump PowerPoint every time: even  when they go wrong the audience enjoy them!
  • But a few sparse PowerPoint slides can also communicate volumes.

The whole business of communicating on stage is subtle and that some knowledge of ‘stagecraft’ is essential and this is not my strong point. I feel this particular talk would have been better if I had had a chance to do it just once before hand!


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