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The second lecture in Bassano February 12, 2008

Posted by dorigo in personal, physics.

Two weeks ago I visited a high school in Bassano del Grappa, Liceo Brocchi, to give a lecture in the context of the Masterclasses 2008. The lecture discussed the history of 20th century nuclear and subnuclear physics, and I covered some of the main issues up to the November revolution of 1974, when the charm quark was discovered and quarks were recognized as physical entities.

Today I gave the second part of the lecture. Two more hours spent discussing the discoveries that led to the verification of the Standard Model, and the hunt for the Higgs boson. I was surprised by the attention and interest of the students, who did their best to understand my garbled babble and messy scribblings on the blackboard. Definitely an afternoon well spent, considering that among these youngsters are probably hiding one or two successful particle physicists of tomorrow. The slides (in Italian, sorry – although I think a good part of them are plots, pictures and charts) can be downloaded from this link. Let me translate only the last one here: 


1. Chiara Bortignon - February 12, 2008

Ciao T!

Facciamo che mi arrogo il diritto di sentirmi parte del pubblico a cui hai rivolto quel good luck?!?in questo momento sento di averne seriamente bisogno!:)

Sono sicura che sarai stato interessantissimo a lezione e per niente “messy”!

Buona serata,

2. Andrea Giammanco - February 12, 2008

ahah did you take the Lupo Alberto strip from an old presentation of mine, or is it just coincidence?
(In case, of course, it’s fine: as you maybe remember, I borrowed a couple of figures from you in the past.)

3. nige cook - February 13, 2008

This is a very optimistic post. What students need to be aware of, however, is that they might not be able to actually do a research degree, say a PhD, in an area of fundamental physics that interests them, say a neglected backwater where one has a chance of striking gold (so to speak).

Friends of mine in the UK who have done PhD’s in experimental physics were controlled by the department head and thesis advisors, who ensured that the work was on the frontiers of mainstream research. They were not free to investigate what they found interesting, or areas which were totally unknown. They had to build on someone else’s work in an existing frontier. The reasons were chiefly due to industrial sponsorship of research.

I’d like to investigate an alternative to the U(1) x SU(2) electroweak theory in the Standard Model. The Yang-Mills SU(2) symmetry involves two types of charge and results in two charged massless gauge bosons and one neutral gauge bosons (the unobserved Higgs boson is supposed to make these three gauge bosons massive and hence short-ranged at low energy). The Abelian U(1) symmetry involves one charge and one massless gauge boson, which is currently used to model electromagnetic charge and photons.

From the fact that you might get two types of electric field (positive and negative) around electric charges, and it is possible to explain both the repulsion of similar charges and attraction of dissimilar charges by having two types of charged massless gauge boson, one alternative to the existing U(1) x SU(2) + Higgs field, for the electroweak theory, is that the mass-giving (Higgs type) field doesn’t actually give mass to all of the two SU(2) massless charged gauge bosons mass at low energy.

Maybe only a portion gets mass (in wuch a way that the resulting massive weak bosons only interact with left-handed spinors), and the rest of the charged massless SU(2) gauge bosons remain massless at low energy, giving electromagnetic force. This could work because if there is exchange of charged massless gauge bosons between all similar charges, the charged massless gauge bosons will (when there is equilibrium in the exchange) be passing in opposite directions so their magnetic fields will have opposing curls and cancel out.

This idea comes from experiments by Wafer scale chip engineer and computer signal cross-talk theorist Catt, who showed that when you charge up a length of cable, energy enters at light velocity and has no means to slow down thereafter. The cable is charged up like a capacitor in a series of steps which arise due to reflections at the unterminated ends of a transmission line being charged up (see http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=4039191 and http://www.ivorcatt.org/icrwiworld78dec2.htm but beware that Catt is an experimental electronics engineer, not a theoretical physicist, and makes some errors in interpreting the experimental facts to his physics concepts). Although there is a drift current of electrons in the cable, it can be shown that most of the energy is being carried by the electromagnetic gauge bosons, and that once the cable or effective capacitor is charged up, there is an equilibrium of boson energy vacillating (or oscillating) at light velocity in both directions along the transmission line, just like two logic signals in a computer transmission line travelling through one another from different directions (the electric field components add, the magnetic field components cancel).

So you can use such modern logic-step crosstalk experimental work in electromagnetism (which was unknown when the U(1) model of electromagnetism was being formuled many decades ago) to show that electric fields may be mediated by charged massless, not neutral, gauge bosons. So SU(2) without the Higgs field may be the correct model for electromagnetism, not U(1).

This is just one line of research which is based on new experimental work on electromagnetism. I’ve written several articles over the past decade about Catt’s research in Electronics World, a British journal, but for various reasons – mainly Catt’s general hostility towards modern physics and people like me, just because of the speculative excesses and elitism of areas like string theory – there is very little interest.

Mainstream physics journals use peer-review or editorial censorship to eliminate anything out of the ordinary that originates from someone without a mainstream reputation or even a PhD. I did QM and GR (cosmology) modules at university, but it is still extremely difficult studying the Standard Model from books (Ryder’s QFT book is the most lucid introduction I’ve found), while working in IT and having nobody to discuss it with: I can grasp whatever maths I need, but it’s not always clear what physical evidence it is based upon. E.g., is weak hypercharge (in the Gell-Mann–Nishijima formula) a real quantum field charge, or just a mathematical concept (twice the difference between electric charge and weak isospin charge)?

Because gravity is always attractive, it can be most simply modelled by a neutral gauge boson exchange between gravitational charges, which for technical reasons would push masses (etc.) together. The average hypercharge of particles is twice the electric charge ( http://en.wikipedia.org/wiki/Hypercharge ), so could effects from exchanges of the massless neutral boson of SU(2) account for weak hypercharge? Sorry if such questions are too boring/off-topic.

4. Tony Smith - February 13, 2008

Thanks very much for putting the slides on the web.

This may be a bit off-topic, but it is about influencing the future of physics.

The publisher Arnoldo Mondadori Editore is controlled by Berlusconi.
Since 2006, its French branch edits the magazine Science et Vie.
The January 2008 issue of that magazine has a cover saying:

“… Theorie du tout Enfin!
Un physicien aurait trouve la piece manquante
Entretien Exclusif avec Garrett Lisi …”.

The issue contains two articles, entitled
“Enfin une théorie du tout?”
the second article seems to me to be pretty well balanced (quoting pro and anti Lisi people and emphasizing need for experimental verification), saying:
“… La violence des réactions illustre bien la crise de la physique théorique moderne …
“Pro” et “anti” ont désormais un intérêt commun: mettre la théorie à l’épreuve” …
Si la théorie de Lisi a fait des prédictions correctes que l’expérience pourra révéler,
alors le plus gros du travail sera fait.
Et une seule figure géométrique rendra compte de l’Univers tout entier…”.

The illustrations in the articles are very nice.

I like Garrett Lisi, and I like E8 physics
(as I mentioned in my guest post here a while back)
I wonder about the politics of who and what get cover treatment on such magazines as Science et Vie,
since I know very little about Euro-Politics, what influence such magazine coverage might have.

Tony Smith

5. Tony Smith - February 13, 2008

Sorry – my clumsy editing left out the title of the second article in Science et Vie of January 2008, which was

“Ce qu’il faut maintenant vérifier…”

Tony Smith

6. dorigo - February 13, 2008

Hi Andrea,

no, it was indeed a coincidence. I actually do not remember where I got the strip from, but I believe it wasn’t in a talk.


7. dorigo - February 13, 2008

Ciao Chiara,

figurati! Arroga, arroga pure. Quanto alla lezione, ho davvero messo tanto materiale – un errore che faccio sempre – ma questo mi ha permesso di parlare di diverse cose interessanti.

In bocca al lupo,

8. dorigo - February 13, 2008

Dear Nigel,

in Italy universities are free – from funding 😦 – but researchers are thus left a chance to follow more exotic paths if they like. Same goes with PhD students. 80% of the grants are not finalized in a specific direction.

I understand your frustration with the autoreferential nature of the scientific publishing world. However, I have no recipe to improve the situation.

I do love Ryder’s book, I use it as a reference quite often. Last time was when I refreshed my memory on QFT before the course I gave last fall.

As for weak hypercharge, as far as I understand it it does not stand on the same footing as electric charge.


9. dorigo - February 13, 2008

Hi Tony,

alas, yes, Berlusconi controls much of italian press, and some also abroad. I think he is not concerned with what gets published and what doesn’t, particularly abroad – he just cares that it makes money.

I am much more concerned with the fact that we will probably have him again as premier in a few months, which will mean more shortage of funding for basic research (everything must give in order to enable a 0.5% tax cut), a political control over scientific research institutes, and other trivialities of that kind.


10. Guess Who - February 14, 2008

Nige, let me surprise you and offer some sympathy. Yes, doing a Ph.D. in physics is a lot like doing an apprenticeship in a medieval guild. It may be right for most, in the sense of giving them a fighting chance to actually get some papers out, graduate in a finite time and then get a real job, but is notoriously ill suited to the kind of rebel spirits who end up making the real breakthroughs, if they somehow manage to survive long enough.

That said… the group theory of electroweak interactions (and then of GUTs and preon models) was thrashed out a long time ago, in the early 70s. The stuff is so old you won’t find much about it on the Arxiv or even in textbooks, which tend to just give you a few simple examples and move on. If you are really interested, you need to go back to the original papers. Here is a good one if you want some nitty gritty:


What you should take home from it is that the question essentially reduces to a mechanical task: specify a Lie group and a representation, write down the most general renormalizable symmetry breaking potential (unless you are willing to handwave about yours being a low energy effective action, to be completed) and find the minima. It’s been done ad nauseam, and the winning model has been tested to a ridiculous level of precision.

Doing away with the Higgs the way you suggest won’t work. Pure SU(2) without a Higgs is actually many a field theorist’s favorite toy model of QCD, since it’s simpler but still features its million-dollar property: confinement. Your charged gauge bosons would not be free to fly around (and wreak unspeakable havoc…); they would be confined to singlets, just like QCD’s gluons. Google up “Abelian dominance” for a popular approach to this, you may like it.

11. Tito - February 14, 2008

Hello Tommaso,

I’m from Bassano. I was a student at Liceo Brocchi a few years ago. Now I’m working on a thesis about gravitational waves at the university of Padova. Studying physics was an amazing experience, too bad it seems so difficult to explain it to young people.

I really like your blog and I hope that more teachers will adopt this interesting medium to talk about their research efforts, lessons and also personal life in the future. Keep up the good work!

12. dorigo - February 14, 2008

Hi Tito,

thank you… Blogs have become an important means of communication… In Bassano there was a lot of interest for gravitational waves when I mentioned Lisa and other searches. Good luck with your work!


13. Amara - February 14, 2008

Dear Tommaso: I am beginning to see blogs as the missing bi-directional links on the Web from Vannevar Bush’s ideas for information transmission. Bee got me thinking alot about this from her recent: “Growing Mountains” http://backreaction.blogspot.com/2008/01/growing-mountains.html post.

There were early attempts, one might say: ‘before their time’, at ways to bring about a more communicative arena to the Internet, for example with Project Xanadu. John Walker (of Autodesk fame), even provides/ed a subset of the Xanadu ideas in his ‘Hack Links’. Later another project called Crit.org gave readers a way to seriously critique the contents of a web page in a layer that sat on top of the page, giving the readers a means to have a dialog about it. For whatever reason, that did not gain widespread use, either. So now we have blogs.

With blogs, we have the author of a piece of text giving a means for his/her readers to give him/her feedback in the Comments section. Such a medium, might not be as ‘efficient’ as bi-directional links, but I would call it ‘richer’ and more suitable to a salon-type, conversational environment, perhaps like the face-to-face salons of one or two centuries ago. It perfectly fits the web, and addresses a complaint I heard (and made) ten years ago that the Internet is too impersonal.

For scientists, such a mechanism is a fine way to help disperse the stereotype that scientists sit in ivory towers, ‘out of touch with reality’. Perhaps _some_ are.. but in fact, most scientists are just people like everybody else, except their work might not be as transparent to the outside world due to the nature of their investigation tools (instruments and computers and scientific papers). So here is the blog value: helping scientists to be more transparent, to share their work lives, cultural lives, and pieces of their personal lives with the rest of the world. Thank you alot for this one.

14. dorigo - February 15, 2008

Hi Amara,

I also think blogs are not a transient phenomenon and are a very interesting new way for sharing information and as a means of creating aggregations and places for discussion. Of course blogs are useful to scientists, but they have also shown to be useful for political and ethical discussions. And newspapers and magazines are more and more turning to blogs as a primary source of information…

And you of course do not need to thank me – thank you for contributing instead.


15. Andrea Giammanco - February 15, 2008

Well, no, blogs are only Ivory Towers where the master of the tower benevolently listens to the villagers surrounding his tower.
I’m not talking only about scientific blogs, but about blogs in general (and, trust me, I know the matter very well.)
What you are dreaming about is a webforum, where experts are mixed with laymen on an equal basis.
There are examples of this, by the way.

16. dorigo - February 15, 2008

Hi Andrea,

well, I agree in part… IMO, how much ivory and how much wood depends on the “master”.

In this blog, I try to give a voice to whomever wants to speak. I never censor anybody save ad-hominem attacks, and I offer a chance for a guest post to whomever has something interesting to discuss.

Of course, a web-forum is in principle a simpler way to do this. But the limit of web forums is that you can hardly control signal from noise; and there tends to be too much going on at any given moment, which forces you to follow only what you are interested in, making it a more impersonal place – too big a party, if you will. In blogs, usually noise stays at a low level – mostly because those who take the pain to comment a post usually have something interesting to say.

If a blog is a dinner table, a web forum is a new years’eve party at a disco dancing. The latter allows to interact with more people, but the former is less noisy and usually a more constructive experience – unless you want to get laid, of course 😉


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