Class of 2023

 It's undergraduate graduation day for Physics students at the University of Surrey.  I came dressed in my fancy robes (Open University MSc) and enjoyed seeing the students in their University of Surrey robes walk up to the front of Guildford cathedral to get their degrees.  Often I would stay for the reception after the ceremony, but not today.  The reception is the place where I can catch up with now-departed students and meet their proud parents.  That's really the best part of the day, but I had another appointment today and couldn't stay for it.  Usually, I would be able to get a picture of me with some of the students, but today, I only managed to be in a picture with other staff members as we waited outside the tradesman's entrance, as tweeted by my colleague Caroline.  I'm the tall one in blue:

Ready to celebrate with @SurreyMathsPhys 😀 Congratulations to all graduating today! pic.twitter.com/76G06lX3Vl

— Caroline S-T (@Dr_CST) July 19, 2023

There was no mention of the Marking and Assessment Boycott at the ceremony, as has happened at some other Unis:

Thousands of us graduating this year will do so with no mark, no classification….

Due to Universities failing to meet @ucu demands thousands of us will walk across the graduation stage with an empty degree.

So here’s what @SussexGlobal at @SussexUni did.

We protested pic.twitter.com/yuUPdnOKEW

— Jess Leigh she/her (@jessjleigh) July 19, 2023

The good news, announced cooincidently today, is that the USS pension scheme is now in surplus, and the industrial action we have been taken to restore our lost benefits looks like it might have succeeded in part.

Car fire in Guildford

 I am working from home today, and during a break I took for lunch I went for a walk through the town centre in Guildford.  I was just heading back to home when I noticed a big plume of black smoke coming from somehere in the centre of town.  It turned out to be a raging fire on Bridge St, which as I got closer looked like a car fire.  Perhaps it was foolish to walk towards it, but I saw a crowd already assembled, and a police cordon to keep people at what I suppose was deemed a safe distance.  I guess the police have ample experience with car fires and how explosive they can be.  

I hope that no-one was trapped inside, as the car was fully engulfed and looked quite ruined by the time I got there - which was at least long enough after it started for the police to have arrived and cordoned off the road.  As a modern spectator with a cameraphone, I took a photo, below.  

What is ab initio?

The title of this blog post is also the title of a paper on the arXiv today by Ruprecht Machleidt from the University of Idaho: https://arxiv.org/abs/2307.06416.

The phrase ab initio to my mind, and to Ruprecht Machleidt's, is sometimes used quite loosely.  He describes is at synonymous with "microscopic" nuclear physics in the following way

The tenet of microscopic nuclear theory is that atomic nuclei can be accurately
described as collections of point-like nucleons interacting via two- and many-body
forces obeying nonrelativistic quantum mechanics—the forces being fixed in free-
space scattering.
The microscopic or ab initio approach to nuclear structure and reactions is then
defined as calculating the properties of nuclei in accordance with the tenet.

To me, a microscopic approach is one which works at the level of individual nucleon wave functions - so e.g. the shell model would be a microscopic approach, while the ab initio approach is the particular microscopic approach that uses free-nucleon forces to build up nuclear structure.  In that sense there is such a thing as an ab inito shell model that can be different to the generic shell model.  

I also would allow "ab initio" to be used, perhaps even more legitimately, for those theories that consider nucleons to be more than point-like, and to acknowledge the substructure.  

One of the points made in the paper is an assessmnet of some so-called ab initio work which is judged, by Machleidt, not to be ab initio by his criteria, and he gives a kind of roadmap of what the future should hold for real ab initio calculations.  

I enjoyed his historical perspective of the battle between what-he-calls-microspic and the effective interaction communities, and I don't much mind that people use phrases like ab initio to mean different things, when it can be seen as either a general and somewhat ill-defined class of theories, or as brand marketing. 

My favourite journal letters

 Many scholarly journals come in multiple editions catering to different (sub-)fields.  E.g. The Physical Review for many years had Physical Review A, Physical Review B, Physical Review C, Physical Review D, and Physical Review E, as well as a letters journal.  Now, there are a few others which are not denoted by single letters, and one that is: Physical Review X.  

But taking all journals from all publishers I have ever published in, what have I appeared to favour?  Well, the graph below reveals all:

 

C is a clear leader, mainly thanks to Physical Review C, while G is a distant second (entirely due to Journal of Physics G).  A, B and E all have a showing, but D and F and anything after G have yet to appear.  There we go - it's always good to have something to aim for in one's career.