all good things come to an end

The final day and a half of the Erice Unconventional Computing workshop were also good, but without photos.

The Tuesday was also scheduled 9am to 7:10pm, but due to some unfortunate cancellations, we had “free” time from noon until 5pm.  A small group of us took the opportunity (moving leisurely from the gelato shop, to a Pizza restaurant, to the conference refreshment room) to sketch out a 20 year research vision, and a shorter term research plan, based on our previous work plus what we had learned at the workhop itself.  Next we have to consolidate the ideas, and write some research proposals (oh, and do the research if we win the funding, of course).

Tuesday evening was the workshop dinner, in the posher of the various restaurants we have been exploring, and not the standard set menu either.

Wednesday was only a half day, and mostly a discussion session of what we had learned, and what to do next.  A slot for andother workshop in 2024 has already been booked, so that’s something to look forward to!

The drive back to Palermo airport was in the light, so I could see some of the scenery I missed on arrival.  Since my flight wasn’t scheduled until 9:45pm, I had the oipportunity to experience the airport cuisine.

The flight was delayed. Surprise.  Not as bad as the over 3 hour delay on the way out, but "only" an hour and a half.  This meant I was passing through Stansted at 1:30am, rather than just before midnight as planned.   The drive home was also longer than planned, since the motorway was closed for roadworks, and I had to use the back roads.  So I got home at 3am, rather than the 1am I was hoping for.  Still, at least I didn’t have to get up early this morning to go to a workshop!  Hopefully I’ll be less zombie-like and sleep deprived tomorrow.

All in all, a great workshop, with excellent talks and ideas and conversations, plus gorgeous weather, and delicious gelato.  If only one could be at these places without having to travel.

excursion to Segesta

The early morning weather has been getting clearer each day, and this morning I could actually see a, still slightly hazy, view from my room window when I got up.

I experimented with panoramic settings to get a great, if slightly curvy, view from the tearoom window.

Then down to the lecture room, where today’s schedule of talks started at 8:30am, but finished 1pm, as today is excursion day.  We all piled on to a coach, which took us to the even more historic site of Segesta.

As we arrived at the entrance, we could see a hint of the Doric wonders to come.

the top of the temple just visible above the trees

But first, we hopped onto a shuttle bus (that for some reason was called free, yet cost 2Euro) that took us up to some ruins and a Greek theatre.  Both the acoustics and the view were fabulous.

We inspected various ruins for a while, then hopped back on the shuttle bus to take us back down the hill.  The winding trip down gave us several glimpses of the temple from a distance.

Once back down to the entrance, it was only a short walk up to the temple itself.  (Despite not being far, I needed a short stop part way up, due to post-Covid lack of puff.)

wow !

The roof hasn’t fallen down: it was never erected.  The temple was never completed, and has stood like this for two and a half thousand years.  Signs of partial completion include no internal structures, lack of fluting on the columns, and the construction “knobs” on the base stones, used for attaching ropes.  These construction signs are not visible on completed temples, as they would have been chiselled off to give a smooth final finish.

Unlike the ruins up the hill, the temple was never dismantled by the locals for its stones, as it is “too remote”.  (Mind you, the ruins up the hill aren’t all that accessible, either!)

The temple is 6 columns wide by 14 columns long, breaking the standard “n by 2n + 1” formula.  It was difficult to get a good shot of the side, due to the length.  Panoramic view gives a weird curve.  But I eventually managed to get far enough away, taking care not to hurtle down into a chasm, to take a normal shot of the entire side view.

wow !!

a view from below

fearful symmetry

Back down to the entrance, and just time to get a gelato before piling back onto the coach, and back to Erice.

a walk around the town

Sunday at the Erice workshop is another packed schedule: 9am until 7:10pm (with again the 9pm-11pm poster session).  Despite the long days, we do get scheduled a 2 hour lunch break.  Lunch is available at a selection of the many restaurants, and there is a workshop set lunch: a plate of pasta and sauce, followed by a plate of meat and green salad.  After ordering, it takes a while to arrive, because it is gloriously, freshly cooked.  (Hence the need for 2 hours.) However, today I wanted a look around the town, so skipped the restaurant option, and just had a cheese and salami roll from the local catering, before setting off with a colleague to explore.

Narrow streets led down past a bell tower to a walk around the perimeter, with views of castles and the rest of the town just seemingly growing directly out of the rock.

bell tower glowing in the sunshine

castle growing out of the rock

castle close up

the whole town just growing out of the rock

On our way back up to the venue for the afternoon session, we passed a gelato shop, realised what we had seen, retraced our steps, and went in.  I had the most amazing and darkest chocolate ice cream I’ve ever seen.  I think we’ll be visiting there again.

an old town

Although it is a Saturday, we had a full schedule of talks, timetabled 9am to 7:40pm, then a poster session after dinner!

After getting a full night’s sleep, I have been feeling a lot more alert today.  Apart from when some boiler or fridge rattles for a few minutes, my room is utterly silent: thick stone walls and essentially no traffic contribute to this.

On the way up to breakfast in a different building, I took this photo of the corridor out of the building where my room is:

gorgeous

My room is just around the corner from the main conference venue, which has this magnificent entrance:

The streets are all paved with this form of cobbling.  After hundreds of years of wear, it is somewhat slippery.  That’s not a problem on level surfaces, but most streets in Erice slope dramatically.

This is the street up to the breakfast room, and tonight’s poster session; many streets are much steeper than this.  I picked my way up it carefully, to have a look at the posters, then picked my way back down again even more carefully.

An extremely full day, of wonderful talks and posters.  Off for another good night’s sleep, to get ready for more sessions tomorrow (yes, on Sunday!)

view from a conference accommodation window

I am attending the Unconventional Computing workshop an the Ettore Majorana Foundation and Centre for Scientific Culture in Erice, Sicily.  I’ve wanted to attend an Erice event for a long time now, as it is a famous location for scientific conferences.  So I was concerned when I caught Covid, but fortunately I recovered in time.  I arrived at the centre about 3am (due to a more than three hour delay in my flight; thanks Ryanair).  The weather forecast is full sun all week, so I was surprised to see this out of my window this morning:

However, the early morning mist had mostly lifted by the first break.  We trooped up a stone sprial staircase from the lecture room to the tearoom, to be greeted by a most fantastic view: the room is open to the scenery:

The photo just doesn’t do justice to the effect.  The light is amazing.  Going closer to the opening (taking care to avoid falling down the unmarked black steps against the black floor on the way) gives a wonderful view over the historic town of Erice:

Look closely at the roofs, and you will see lines of rocks on the tiles.  Why?

And looking further out we see this magnificent view over the Mediterranean:

After this break, it’s my turn to present, on less than five hours sleep and with a bit of a post-Covid cough. Let’s see how it goes!

oh well

 Inevitable sooner or later, I suppose:

QBism: the future of quantum physics

Hans Christian von Bayer.
QBism: the future of quantum physics.
Harvard University Press. 2016

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Quantum mechanics is notoriously unintuitive, with its “collapsing wavefunctions” or “many worlds” or whatever is added as an interpretation to its weird predictions. Yet those predictions belong to the most accurate physical theory known. 

Quantum mechanics seems to say we have to give up some cherished notion of the world: if we want locality (no “spooky action at a distance”, only local interactions that propagate), we can’t have realism (the idea that there is some definite thing or process there), and vice versa. Quantum Bayesianism lets go of reality, but in an interesting way. 

This brilliant little book takes the reader through a description of the weirdnesses of quantum mechanics, and the interpretation of Bayesian statistics, before applying the latter to the former. 

The key idea of Bayesian, as opposed to frequentist, statistics is that probabilities are about our knowledge of the world (we assign a prior probability to a fair coin toss of 50% of landing heads, because we don’t know all the details of the initial spin, the air currents, etc). Bayesianism defines how to update this prior knowledge (the 50/50 chance) with a new probability once we have further data (anything from more knowledge about those initial conditions, to an observation of how the coin actually landed). So in QBism the probabilistic quantum wavefunction is interpreted as our prior knowledge of the system. This gets around “wavefunction collapse”: we just update our prior with the additional observational data. It gets around “Wigner’s friend”: Wigner has one prior wavefunction, his friend, who has observed more of the the situation, has an updated, and therefore different, wavefunction. The wavefunction belongs to the observer, not to the system. 

Quantum mechanics allows us to calculate the best possible prior from our knowledge of the system. What makes quantum mechanics weird is that a calculated wave function that says a photon has a 50/50 chance of doing something, say, is the best possible knowledge we can have of the system: unlike in the classical case, it is not possible to improve the prediction by having more data about how it was set up. This is why we have to give up “reality”: the wavefunction isn’t “real”, because it is not a property of the system itself, it is just the best possible description of it. There is no underlying “real” system that “knows” what the actual answer will be (unlike the classical coin toss). Once the photon has interacted with something, the system has changed, and we can update our prior with the new observed data. 

This loss of “realism” does not mean QBism denies the existence of a real world “out there”. It instead leads to a startlingly different view of that real world. The world is not a deterministic automaton, set going at the start, trundling along a pre-determined track. It is a world undergoing constant creation by quantum systems (which may include observers) interacting. 

[p208] Understood in this way, the QBist universe is not static but dynamic; less like an intricate clockwork and more like the interior of an evolving star that is not alive in the conventional sense but bubbling with creative energy and continual surprise. It is real but veiled, objective but unpredictable, and substantial but unfinished,

von Bayer writes in a very accessible way. I admit, the sections on the delayed choice and the GHZ experiments could have gone more slowly. But overall, the exposition is brilliant: on quantum mechanics, on Bayesianism, and then on the combination. This book changed my world view.

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For all my book reviews, see my main website.

turning heads

Many minor things have changed for the first time in a lot of people’s lives, due to changing the soverign after 70 years.  His Majesty’s Government; King’s Counsel; His Majesty’s Revenue and Customs; ...  

And the coins will change.  The design of the new 50 pence has been released:

There has been a lot of discussion about the different direction the head is facing.  But that is not a change of a 70-year constancy for some of us.  On 15 February 1971 the UK “went decimal”, changing its coinage from pounds, shillings, and pence to the new decimal coinage.  (If you have ever wondered why people occasionaly say “what’s that in old money?” when asking for something in less confusing units or language, that’s because it was a very common phrase while people adjusted.)

Before 1971, there were coins from multiple reigns in circulation (and for a while after, since the old one shilling / new 5 pence and the old 2 shilling (florin) / new 10 pence coins coexisted for a while).  As children, we enjoyed finding the occassional very old coin.  Here are some pennies I found in my change in the 60s, and kept as souvenirs:

old pennies: Victoria, Edward VII, George V, George VI, Elizabeth II

So we knew the heads faced in different directions.

Coin designs didn’t change as much then, either:

only a subtle change in Britannia from 1907 to 1962

The main change was the amount of Latin, and the amount of its abbreviation, on the front.

So, the head has turned once more.