What Is the Meaning of Fractional Electric Charge? by Peter Rowlands

If you do not understand why your rating dropped down. As I found ratings in the contest are calculated in the next way. Suppose your rating is [math]R_1 [/math] and [math]N_1 [/math] was the quantity of people which gave you ratings. Then you have [math]S_1=R_1 N_1 [/math] of points. After it anyone give you [math]dS [/math] of points so you have [math]S_2=S_1+ dS [/math] of points and [math]N_2=N_1+1 [/math] is the common quantity of the people which gave you ratings. At the same time you will have [math]S_2=R_2 N_2 [/math] of points. From here, if you want to be R2 > R1 there must be: [math]S_2/ N_2>S_1/ N_1 [/math] or [math] (S_1+ dS) / (N_1+1) >S_1/ N_1 [/math] or [math] dS >S_1/ N_1 =R_1[/math] In other words if you want to increase rating of anyone you must give him more points [math]dS [/math] then the participant`s rating [math]R_1 [/math] was at the moment you rated him. From here it is seen that in the contest are special rules for ratings. And from here there are misunderstanding of some participants what is happened with their ratings. Moreover since community ratings are hided some participants do not sure how increase ratings of others and gives them maximum 10 points. But in the case the scale from 1 to 10 of points do not work, and some essays are overestimated and some essays are drop down. In my opinion it is a bad problem with this Contest rating process.

Sergey Fedosin

Dear Sergey

Thank you for this. I don't understand it either. It seemed to happen overnight. I don't have any idea how these things are organized but it seems strange to me that contestants are allowed to rate other contestants' essays.

It would be better if an independent panel simply read all the essays from the outset.

Best wishes

Peter

From an experimentalists' point of view, which is my perspective, this essay raises a number of interesting points, all of which have a bearing on what is now the main thrust of Particle Physics and therefore all of which are of importance and significance.

The SM has grown up to be the triumphal edifice that it is because experiment has verified many of its predictions with remarkable precision. These predictions depend on the acceptance that all the degrees of freedom with their defined properties in field theory dynamics, work - together (and this is the point) - in calculations for specific measurements which test only some (the rest of the point!) aspects of the SM at once.

An example, relevant to the author's essay, is quark charge where there have been many tests with experimental data demonstrating that the calculations are correct in assuming the SM assignments of charge 2/3 and -1/3 to the Dirac fermion degrees of freedom, the quarks. Periodically in the last three or more decades claims have been made to rule out integer charged quarks. Though always first claimed to be definitive, in the fullness of time it has been realised that it is possible within the framework of the principles underpinning the SM to adjust properties of the degrees of freedom and/or to alter aspects of the SM calculations in acceptable ways which render the hitherto definitive tests to be less than conclusive. In short in terms of this example, we have plenty of corroborative evidence that measured observables are consistent with the SM fractional quark charges, but we to date have never been able to measure directly the charge on a quark, or indeed even just to observe directly quarks. A latter day JJ Thomson and/or R Millikan have yet to manage to make this measurement definitively for very good reason.

That this is the case is no criticism of physics, experimental or theoretical, rather it exemplifies the way science always progresses.

Rowlands is in essence highlighting this truism, but in a way that we should take on board. It requires the humility to be open minded about what humanity has achieved in understanding the physics of the Universe, and in taking advantage of that understanding. He is saying that we should always be aware of the danger of accepting of necessity the assumptions, in his case the degrees of freedom and their numerology in the always rigorous theoretical approach which is essential for meaningful prediction. Our humility should be such as to recognise that to date we may have been unable to identify from a myriad of possibilities that what we use so far works because someone, for example Gell-Mann and Zweig, demonstrated out of luck, good judgement or serendipity, that their SU3-flavour group structure worked for spin1/2 fermions with fractional charges. We never can rule out other possibilities for certain because we haven't chanced upon, or conceptualised, them yet.

I find this essay to be very thought-provoking, and also innovative. We ignore it at our peril if we really deep-down are driven by a wish to understand what makes the world work, and not by other extraneous, misplaced, and in many ways totally irrelevant, criteria. For I am haunted by many decades ago my supervisor saying to me that of course quarks are infinitely massive and very tightly bound in hadronic matter because they have never been, and will never be, observed directly. I now see quarks every day as I look at events from the LHC and the jets that are so beautifully apparent. My supervisor, and myself at the time, had completely the wrong perspective of the nature of quark degrees of freedom, their properties, and the present day perspective of confinement in a non-abelian quantum field theory. Rowlands is just saying this all over again in the present-day context of the SM, and we should be humble enough to take him to task and ask him for further predictions when he has them, for we will measure alpha_EM at the scale of his distinct prediction sooner rather than later! If I could vote (how does one?) I would vote for this submission.