Spectrum of anti-hydrogen?

What does the spectrum of anti-hydrogen look like?

This question came up at our Maths/ Physics Seminar Series on Wednesday, during a presentation I gave on the forthcoming experiments at the LHC (slides here).  It’s a good question, I never thought to ask it before. Before I look it up, here is my guess at an answer – any comments welcome.

First a definition: as you know, antimatter is the name given to matter consisting of elementary particles in which the electric charge (or other quantum property) of each particle is the reverse of that in ordinary matter (see blog title). Just as a Hydrogen atom consists of an electron orbiting a proton, an anti-Hydrogen atom consists of a positron orbiting an anti-proton. However, although antiparticles are often found in cosmic rays or produced in accelerators,  anti-atoms are very rare: only a few atoms of anti-Hydrogen are made at accelerator facilities around the world.

My guess is that the sprectrum of anti-H looks exactly like that of Hydrogen. After all, the emission spectrum of Hydrogen is due to an excited electron jumping from the excited energy level down to a lower level(s): presumably the positron in anti-H has the same separation of energy levels, so I can’t see how there would be any difference in the light emitted.

Pictorial representation of H and anti-H

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However, there is a problem with this answer: how do we detect anti-atoms if their spectrum is the same as normal atoms? By deflection in a magnetic field, you say – this is how the positron was first discovered. But anti-atoms are neutral and in any case antimatter is not always matter of opposite charge, sometimes it is another quantum property that is swapped (consider the anti-neutrino). Indeed, how do we distinguish anti-neutrinos from neutrinos? I’m not sure, but I know we can.

Also, I think I  read somewhere that we have detected clusters of antimatter in some places in the universe. Again, how do we know it’s antimatter? These sort of unexpected questions are what makes giving a seminar worthwhile..

It Must Be Clear

On Wednesday, I’ll give a seminar on Academic Writing to our research students as part of their generic skills course. Of course, my own experience is in technical writing for science journals, but our school of research has discovered that most postgrads find tips on writing very helpful, irrespective of discipline.

I guess the ability to state what you mean unambiguously is an important skill for any academic, whether you are writing an abstract, a grant proposal or a technical paper. In my experience, mathematicians and scientists do this rather well (contrary to public opinion). For example, I have often noticed that the written text in books on mathematics is usually extremely clear. Perhaps one reason is that we have to develop this skill – conveying the true meaning of relativity or quantum theory is difficult enough without introducing extra ambiguities due to clumsy punctuation.

Ah, punctuation. It’s amazing how good punctuation can clarify the most difficult of concepts, while poor punctuation can render a passage almost meaningless. The basics of punctuation are quite simple to learn and I’ve never understood why so few take the time to refresh their grammar. For example, did you know there are four types of comma? Or that the famous comma-and rule is a myth? (it depends on the context).

However, there is more to good writing than decent punctuation. In poor writing, the problem often runs quite deep – for example muddled thinking produces muddled writing. Another problem is lack of imagination. Some writers tacitly assume the reader already knows what is meant – they simply cannot imagine that the sentence they wrote can be read differently. A third sin is that of overload, again because the writer has not considered how this will read to someone new to the subject.

When I was writing my own PhD thesis, my supervisor refused to correct chapters of text. Instead, he insisted on seeing bullet points for each section, preferably hand-written. I still hear his voice when writing ;

What are the points you wish to make in this section?

Why is this point here and not earlier?

Does it hang together?

Use a new paragraph for every new idea

In real life, it’s fascinating how the professions write differently. Journalists often write well, but tend to state their opinions as established facts. Economists write more accurately, but must be read two or three times. Lawyers tend to use even more obtuse language, rendering the meaning impenetrable. Worst of all are writers in business and politics – they seem to enjoy using vague phraseology, deliberately allowing the text to mean whatever the reader wishes it to mean. To scientists, this is a terrible sin – if you don’t have a clear point to make, why write the piece at all?

You can find the slides I will use for the talk here. In the meantime, here are some hilarious examples of poor punctuation:

Julianna walked on her head a little higher than usual

I must get on my lover

No dogs please

Fan’s fury at cancelled match!

A panda bear is an animal that eats, shoots and leaves

A good book on punctuation, if a little longwinded

A new President

I just caught President Obama’s inauguration speech on our college tv. All of us were highly impressed, from the senior professors to the cleaning women (even my students were riveted). Very impressive and quite moving. I suspect Obama will make a great President and a big difference to the world. It reminded me of old footage of Kennedy, you got a glimpse of the US the rest of us used to be proud of. I suspect many nations around the world are heaving a sigh of relief..

A new President

There were several prominent references to corporate greed, to unsustainable energy consumption and to America’s reduced standing in international affairs. He sounded like he meant it. It will be interesting to see whether an intelligent man who is clearly well-motivated will be able to stand up to the vested interests of ideologues and big business…

So a new President for a new era. I notice that when Democrats get elected they talk a lot about America and American values, whereas Republican presidents talk about republican values…interesting

P.S. Forgot so say the most important bit – during the speechthe new President also said the magic words “restore science to its rightful place”. At long last…

Update: James wants to know where the rightful place of science might be (see comments).

The rightful place of science is where it can be heard by decision-makers, so that world leaders can make decisions based on the best objective scientific advice available. One of the first things the Bush administration did was to move the office of science advisor far from the inner circle of the White House (physically as well as metaphorically). He also installed political hacks and Big Business cronies to top positions in major scientific bodies such as NASA… a huge tactical error irrespective of your political viewpoint.

The result was a campaign of misinformation on science, with many consequences – the most serious of which was the effective stalling by the US of any meaningful international action on global warming for 8 years, to the incredulity of most other nations.

Already, Barack’s choice of scientific advisors has been spectacular – if you want to get a feeling for the views of US scientists on this, have a look at the blogs listed under ‘particle physics’ in the blogroll opposite..

Thoughts on CERN and NASA

I’ve been meaning to point out that you can view the slides used by the incoming Director General of CERN, Rolf Heuer, in his recent inaugural address to the CERN community here.

Rolf-Dieter Heuer

There are many interesting points, but one that comes across clearly is Heuer’s vision of CERN as a global centre for particle research. Of course, one could argue that it already is, but it’s clear from the presentation that the scope of the facility is expected to broaden even further. Fascinating that an inter-european project involving a handful of sparring nations has become so successful that it is now one of the world’s most successful centres for scientific research – and all the more reason for Ireland to join, as I have said many times in public and in the press.

It’s often said that CERN is the NASA of the particle world, but it’s actually more. Quite apart from the opportunity for scientists to work at a top-level facility, with top-level scientists, I think the international aspect of the project is important in itself – perhaps science can give humans a taste of how genuine co-operation of individual nations working in harmony can yield a result that is greater than the sum of its parts…

The world’s largest acclerator (LHC) at CERN under Geneva

Of course, CERN isn’t perfect and I think there are PR lessons to be learnt from the media coverage of the LHC startup:

(i) A spurious story of black hole creation was allowed to dominate the coverage

(ii) A serious technical setback ocurred in the full glare of maximum publicity (the consequence of a single faulty weld)

As a result of these, the general public saw the LHC first as a threat, and then as something that broke down at the first fence….hardly confidence inspiring.

In fact, I saw remarkably few articles in the press on the beauty of particle physics, or the ‘why’ of the experiment. One reason was that sporadic press contributors (like this one) couldn’t get articles accepted due to the sheer volume of articles on the topic by regular journalists (who knew little of the topic). Instead, the public were presented with repeated technical details that interested no-one.

Perhaps it is true that scientists do not convey the excitement of their work very well – but I wonder. I wouldn’t mind a shot at disproving this theory. I’m currently trying to persuade The Irish Times to run a regular column on cosmology and particle physics (The Puzzling Universe) and they seem interested ..we’ll see…

Young Scientist Exhibition

I spent last Friday and Saturday at the BT Young Scientist Exhibition in Dublin.  The CALMAST group at our college do a great job of communicating science to young people and I took a day out to go up and help out with physics demonstrations at their stand at the exhibition. They had super demonstrations covering all the sciences, including a robot that moves and talks, a show on Robert Boyle and simple demonstrations of the science of first aid . My own job was to demonstrate the physics of magnets, plasma balls and the like. It’s fun to do and great see the interest in young people, some kids find it utterly fascinating.

Robert Boyle (Eoin Gill) at the WIT stand (Boyle was born in Waterford)

Galileo (Astronomy Ireland)meets Boyle (WIT)

The WIT robot BENJI meets the Minister for the Environment

Such stands are really a sideshow to the main event. The Young Scientist is a highly successful science competiton for Irish secondary schools, where students from hundreds of schools submit detailed science projects. I didn’t get a chance to see all the projects, but there were some very interesting physics projects, ranging from a study of the surface brightness of disc galaxies to a mathematical model of the human face using factals. Two maths projects that caught my attention were a suggested new avenue for the solution of the Riemann Hypothesis via the Robin formulation and ‘ efficient numerical tests of of Robin’s reformulation of the Riemann hypothesis’ (the latter won 1st prize for individual project). Both these projects were from the same school – extraordinary what inspiration good secondary teachers can give. The overall winner of the competition was an ingenous method of determing the health of cattle using washing-up liqud, you can read about it here.

Of course, the real question is whether such projects and the whizz bang demonstrations next door motivate young people into choosing science as a career. I think they do to some extent as inspiration outside the classroom is often the key to a choice of career. Even if not, a lifelong curiosty about the subject can be fostered.  However, I admit it’s a difficult thing to prove..

New Year resolution:book

My main NY resolution is that I’m thinking of changing the topic of my book. Last semester, I gave a few public talks on particle physics to mark the opening of the LHC at CERN (see ‘My Seminars’ tab for slides). More used to giving talks on the Big Bang, I couldn’t help noticing that it is definitely easier to explain the physics of the universe than the physics of the sub-atomic. Also, there seems to be that bit more interest in cosmology..I guess this is because the study of the origin of the universe has implications for religion and philosophy and so has a wide appeal.

Everybody wants to know whether the Big Bang model is just theory or established fact. And what exactly happened at time zero? (good question). There are also all those sexy topics like Black Holes, Dark Matter, the Arrow of Time etc. Of course A Brief History of Time (Hawking) catapulted cosmology into the public imagination, but I think the interest was always there…

So possibly a change of direction in the New Year. Perhaps‘The Puzzling Universe”, a short, succinct book on the origin of the universe, might be a better seller than “The Story of Atoms”. (I have no interest in writing a popular book that is not popular). Also, I can imagine a spinoff newspaper column on the subject, always a good sign..It’s true there are now lots of books on this subject at the popular level, but that’s no harm. Anyway, many of them either cover far too much (Hawking, Bryson) or are by authors who have little experience of teaching the subject at elementary level. Must ask the students, see which subject they think will sell…

One thing that worries me is that some of the best science books for the public remain relatively unknown, not sure why this is.  For example, I really enjoy the books of Paul Davies, but they are not as wide selling as they should be. Another example is Marcus Chown – I read Quantum Theory Cannot Hurt You over Christmas , a really excellent book. Really good explanations of quantum physics, general relativity and whatnot, all with highly original analogies. Hmm..we’ll see.

The best skitrip

Now that was a holiday. I just got home from one of the best snow holidays ever, a trip to Switzerland with the Frankfurt Ski Club. The club consists of American, British, French and Germans ski enthusiasts who work in Frankfurt and take a coach south to the mountains at every possible opportunity. (Yours truly got involved through a very good friend – I go as often as I can as the trips are always really well organised).

The trip got off to a great start with a gala dinner on New Year’s eve in our hotel on the shores of Lake Geneva. Although I moaned about having to bring a full tuxedo in my ski baggage, I must admit it was nice when I arrived from Zurich to find everyone at the hotel reception dressed to the nines and quaffing champagne. It really added to the occasion and it was great talking to old friends over dinner and making new acquaintances..

Next day we were bussed to Villars, the nearest ski resort. The conditions were fantastic, lovely deep snow from a recent snowfall and beautiful sunshine. One of the best day’s skiing I ever had. Incredibly, these conditions continued for the next four days as we visited resorts like Verbier and Portes du Soleil. I hooked up with some other off-piste skiers in the club and we had some very challenging skiing, including the famous Wall on the Franco-Swiss border in Portes du Soleil.

More FSC photos at http://www.facebook.com/home.php?#/album.php?aid=71716&id=587171690

At the end of the trip I  took the club coach back to Frankfurt – a first as I’ve never been there! I’d heard it said that the coach journeys are one the best features of the FSC trips and it was certainly true on this occasion – it was more like a mobile bar full of friends than a normal bus journey. When we finally got back to Frankfurt, a few close friends decided to celebrate my arrival in their city, so the party went on til late..

This morning, I woke up in a strange city covered in snow. I made my way into the city center to meet a friend for lunch and then took myself on a mini-sightseeing tour of the city. Frankfurt city centre seemed surpisingly nice – an interesting mixture of beautiful old buildings and impressive new skyscrapers, not unike a large version of the financial district in London. Fantastic public transport of course, like everywhere in Germany.

Frankfurt in snow by Max Heidenfelder

Then it was on to the airport and back to reality. There’s no snow in Waterford and it’s too cold to surf. Sigh. Why can’t I live in a civilised country like Germany? Maybe I should apply for a job at CERN – I’d settle for Geneva alright…