When Worlds Collide…

This morning I had a really fantastic meeting with some filmmakers about scientific aspects of the visuals (and other content) for a film to appear on your screens one day, and also discussed finding time to chat with one of the leads in order to help them get familiar with aspects of the world (and perhaps mindset) of a theoretical physicist. (It was part of a long series of very productive meetings about which I can really say nothing more at the current time, but I’m quite sure you’ll hear about this film in the fullness of time.)

Then a bit later I had a chat with my wife about logistical aspects of the day so that she can make time to go down to Los Angeles and do an audition for a role in something. So far, so routine, and I carried on with some computations I was doing (some lovely clarity had arrived earlier and various piece of a puzzle fell together marvellously)…

But then, a bit later in the morning while doing a search, I stumbled upon some mention of the recent Breakthrough Prize ceremony, and found the video below […] Click to continue reading this post

Catching Up

Since you asked, I should indeed say a few words about how things have been going since I left my previous position and moved to being faculty at the Santa Barbara Department of Physics.

It’s Simply Wonderful!

(Well, that’s really four I suppose, depending upon whether you count the contraction as one or two.)

Really though, I’ve been having a great time. It is such a wonderful department with welcoming colleagues doing fantastic work in so many areas of physics. There’s overall a real feeling of community, and of looking out for the best for each other, and there’s a sense that the department is highly valued (and listened to) across the wider campus. From the moment I arrived I’ve had any number of excellent students, postdocs, and faculty knocking on my door, interested in finding out what I’m working on, looking for projects, someone to bounce an idea off, to collaborate, and more.

We’ve restarted the habit of regular (several times a week) lunch gatherings within the group, chatting about physics ideas we’re working on, things we’ve heard about, papers we’re reading, classes we’re teaching and so forth. This has been a true delight, since that connectivity with colleagues has been absent in my physics life for very many years now and I’ve sorely missed it. Moreover, there’s a nostalgic aspect to it as well: This is the very routine (often with the same places and some of the same people) that I had as a postdoc back in the mid 1990s, and it really helped shape the physicist I was to become, so it is a delight to continue the tradition.

And I have not even got to mentioning the Kavli Institute for Theoretical Physics (KITP) [….] Click to continue reading this post

Multicritical Matrix Model Miracles

Well, that was my title for my seminar last Thursday at the KITP. My plan was to explain more the techniques behind some of the work I’ve been doing over the last few years, in particular the business of treating multicritical matrix models as building blocks for making more complicated theories of gravity.

chalkboard from KITP seminar

The seminar ended up being a bit scattered in places as I realised that I had to re-adjust my ambitions to match limitations of time, and so ended up improvising here and there to explain certain computational details more, partly in response to questions. This always happens of course, and I sort of knew it would at the outset (as was clear from my opening remarks of the talk). The point is that I work on a set of techniques that are very powerful at what they do, and most people of a certain generation don’t know those techniques as they fell out of vogue a long time ago. In the last few years I’ve resurrected them and developed them to a point where they can now do some marvellous things. But when I give talks about them it means I have a choice: I can quickly summarise and then get to the new results, in which case people think I’m performing magic tricks since they don’t know the methods, or I can try to unpack and review the methods, in which case I never get to the new results. Either way, you’re not likely to get people to dive in and help move the research program forward, which should be the main point of explaining your results. (The same problem occurs to some extent when I write papers on this stuff: short paper getting swiftly to the point, or long paper laying out all the methods first? The last time I did the latter, tons of new results got missed inside what people thought was largely just a review paper, so I’m not doing that any more.)

Anyway, so I ended up trying at least to explain what (basic) multicritical matrix models were, since it turns out that most people don’t know these days what the (often invoked) double scaling limit of a matrix model really is, in detail. This ended up taking most of the hour, so I at least managed to get that across, and whet the appetite of the younger people in the audience to learn more about how this stuff works and appreciate how very approachable these techniques are. I spent a good amount of time trying to show how to compute everything from scratch – part of the demystifying process.

I did mention (and worked out detailed notes on) briefly a different class of […] Click to continue reading this post

Living in the Matrix – Recent Advances in Understanding Quantum Spacetime

It has been extremely busy in the ten months or so since I last wrote something here. It’s perhaps the longest break I’ve taken from blogging for 20 years (gosh!) but I think it was a healthy thing to do. Many readers have been following some of my ocassional scribblings … Click to continue reading this post

Rattle and Hum

A lot of us have been waiting for a long time to hear this news! The NANOGrav collaboration has announced strong evidence of a background of low frequency gravitational waves emitted from supermassive black hole mergers. Their detection methods are pulsar timing arrays (still one of those fantastically simple, cool … Click to continue reading this post

A Return (Again)

About two years ago I wrote a post entitled “A Return”, upon moving to Princeton for a year (I was a Presidential Visiting Scholar at the Physics department). I reflected upon the fact that it was a return to a significant place from my past, where I’d been transformed in so many ways. Princeton was the first place I visited (not counting airports) in the USA, the location of my first postdoctoral appointment (at the Institute for Advanced Study (IAS)), and its was there that I did a deep enriching dive into the hubbub of Theoretical Physics, at one of the very top places in the world to do so.

Coastal view from UCSB campusAfter that, I moved West, to Santa Barbara, where my next postdoc position was at the Institute for Theoretical Physics at the University of California Santa Barbara (UCSB), now called the KITP. I was very lucky to be able to go from one top place to another, and (as I’ve recently talked about in a BBC interview here) additionally, my field was in a delicious turmoil of activity and discovery. I was able to be a part of the maelstrom (the “Second Superstring Revolution”, and all the gifts it gave us, including better understanding of the role in quantum gravity of extended objects beyond strings (such as D-branes), the physics of quantum black holes, the tools to unlock the holographic nature of quantum gravity more generally (through AdS/CFT), and so on. (I’ve blogged about many of these topics here, so use the search tool for more.)

I’ve been known to say that Princeton was the place where I found my physics voice (Edward Witten was a key guide at that time). Well, to continue the theme, Santa Barbara (with its wonderful research group made up of people from both the KITP and the wider Physics Department) was the place where I started to learn how to use that voice to sing (with the guidance of Joe Polchinski (who sadly passed away a few years ago)).

Well, as you may be guessing after that long introduction, I’m doing “A Return” again, but this time not with some boxes and suitcases of things for a year’s stay: I can now announce that I’ll be leaving the University of Southern California (USC) and (as of 1st July 2023) joining […] Click to continue reading this post

The Life Scientific Interview

After doing a night bottle feed of our youngest in the wee hours of the morning some nights earlier this week, in order to help me get back to sleep I decided to turn on BBC Sounds to find a programme to listen to… and lo and behold, look what had just aired live! The programme that I’d recorded at Broadcasting House a few weeks ago in London.

So it is out now. It is an episode of Jim Al-Khalili’s excellent BBC Radio 4 programme “The Life Scientific”. The show is very much in the spirit of what (as you know) I strive to do in my work in the public sphere (including this blog): discuss the science an individual does right alongside aspects of the broader life of that individual. I recommend listening to […] Click to continue reading this post

What a Week!

Some Oxford scenesI’m sitting, for the second night in a row, in a rather pleasant restaurant in Oxford, somewhere on the walk between the physics department and my hotel. They pour a pretty good Malbec, and tonight I’ve had the wood-fired Guinea Fowl. I can hear snippets of conversation in the distance, telling me that many people who come here are regulars, and that correlates well with the fact that I liked the place immediately last night and decided I’d come back. The friendly staff remembered me and greeted me like a regular upon my return, which I liked. Gee’s is spacious with a high ceiling, and so I can sit away from everyone in a time where I’d still rather not be too cavalier with regards covid. On another occasion I might have sought out a famous pub with some good pub food and be elbow-to-elbow with students and tourists, but the phrase “too soon” came to mind when I walked by such establishments and glanced into the windows.

However, I am not here to do a restaurant review, although you might have thought that from the previous paragraph (the guinea fowl was excellent though, and the risotto last night was tasty, if a tiny bit over-salted for my tastes). Instead I find myself reflecting on […] Click to continue reading this post

W1A

[caption id="attachment_20038" align="aligncenter" width="499"]Brpmpton bicycle rental lockers. Brompton bicycle rental lockers.[/caption]
I’ll be visiting Broadcasting House during my time here in London this week, for reasons I’ll mention later. Needless to say (almost), as a Brompton rider, and fan of the wonderful show W1A, I feel a sense of regret that I don’t have my bike here so that I can ride up to the front of the building on it. you won’t know what I’m talking about if you don’t know the show. Well, last night I was a-wandering and saw the rental option shown in the photo. It is very tempting…

-cvj
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