Presentations are more important than papers: my first youtube video

July 27, 2015

During the past 5 years or so I have come to believe that presentations are actually more important than scientific papers. As a consequence, I have recently spent quite a lot of energy learning how to give better presentations. This is a truly fascinating and rewarding topic. While I find it is difficult, if not downright impossible, to master good public speaking, I’ve very much enjoyed trying to improve how I give my presentations.

Today I’d like to annouce the appearance of my first youtube video:

This is a recording of a talk I recently gave to graduate students here in Hannover. The objective of the talk was to share and channel advice I’ve received in the past years on how to give a good presentation. While I don’t claim to be especially good at giving good talks myself (the excruciating experience of watching myself on video for essentially the first time only serves to underline this!) I have learnt a great deal from other excellent speakers, and I hope that I can at least share a couple of the tips and tricks I’ve learnt.

Depending on the reception to this video it might signal a change in the way I will go about communicating our research. I’ve recently noticed that I am spending an increasing amount of time watching videos of talks at conferences, video tutorials, and miscellaneous other videos (cat videos, unboxings, etc. 🙂 ). It truly is a supremely powerful medium of communication, combining both visual and auditory modes of delivery, and, given that you can pause and skip, I have found it to often be superior to attending talks.

I am still passionate about open science, and open notebook science, and I am always contemplating better and more efficient ways to implement at least some core principles of openness. This is why this blog and my twitter account have become so neglected as of late: I’ve just found that github provides an amazingly useful, superior, and simple tool to achieve this. If you want to know what I’m doing on any given day then you can check out my activity there. (Basically all of my notes are now stored openly there.)

However, github is not the right tool for communicating and sharing ideas. Here I think video is superior, and youtube a natural platform. We’ll see.

I do hope you enjoy watching my video; any comments, suggestions, and criticisms are (actually) welcome!

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An introduction to the continuous limit construction I

May 19, 2014

In this post I’d like to begin to explore what is meant by the continuum limit of a quantum lattice system. This post is meant to serve as the first in a series of intuitive overviews of the ideas involved in the open science project “continuous-limits-of-quantum-lattice-systems” hosted on github.

The continuous limit is a power tool in the condensed-matter theorist’s toolkit: by identifying the appropriate effective field theory modelling the low-energy large-scale physics of a complex quantum system one can bring the fully developed apparatus of (perturbative) field theory and the renormalisation group to bear on a problem, often delivering results unavailable via any other means.

Now I’m pretty sure I’m not alone in feeling confused by much of the available physical literature on this topic. Over the past decade I’ve tried to understand the process whereby a field theory is produced to describe a given quantum lattice system. However, up until recently, this has always seemed like a kind of mysterious black magic to me. I know it has to do with symmetries etc. etc.. But this didn’t really help me! I had so many questions. E.g., how exactly does the state of the effective field theory relate to that of the original lattice system? And, for that matter, how do you know what quantities are “fieldlike” and which don’t admit a field-theoretic representation? That is, what has most puzzled me is the quantitative side of things: ideally what I would like is some kind of map which associates, one to one, lattice quantities with field quantities in an operationally transparent way.

Thus I was very excited when I discovered that there is indeed such a map and, further, is naturally associated with the quantum de Finetti theorem. Here I’d like to explain the idea behind this construction using the quantum information theoretic language of exchangeable states.

Read the rest of this entry »


Yang-Mills theory and tensor networks

April 30, 2014

In my two previous posts I discussed a quantum-information inspired approach to the study of quantum field theory.

So far everything I’ve talked about applies only to standard bosonic quantum fields. However, there are, apart from fermionic quantum fields, another type of quantum field which requires a more careful approach, namely, gauge fields. Read the rest of this entry »


Returning to open science: continuous limits of quantum lattice systems

April 28, 2014

As I mentioned in my previous post, I have been working for some five years on trying to understand quantum field theory from a quantum-information perspective. This has finally come to a fruition of sorts: I’m pretty sure I have an operationally motivated way to build nontrivial nongaussian quantum field states using a variety of tensor network states.

The input to the procedure is any family of tensor network states (or, indeed, any family of states) whose correlation functions diverge in a controllable way as a function of a scale parameter. The procedure then produces a continuum limit with the corresponding quantum field data modelling the quantum fluctuations around the limit.

There are two main ideas behind the procedure: (1) it begins by extending the mean-field formalism of Hepp and Lieb (developed later by Verbeure and coworkers) to identify the emergent continuous large-scale degrees of freedom describing the classical bulk fluctuations (remarkably the continuous degrees of freedom are not prescribed beforehand) — this is a kind of generalised law of large numbers result; and then (2) by exploiting a generalised quantum central limit-theorem type argument the quantum fluctuations around the bulk are then identified and the emergent quantum field operators are subsequently identified. The applicability of this procedure is contingent on the family of input states satisfying certain criteria, which essentially boils down to the ability to tune the correlation length in a controlled way.

A nontrivial result is that several tensor network states naturally satisfy the criteria required by the continuum limit procedure: in particular, for the continuum limit of the matrix product state and projected entangled-pair state classes we recover their recently introduced continuous counterparts and for tree tensor network classes arising from Kadanoff block spin renormalisation and the multi-scale renormalisation ansatz class we obtain continuum descriptions generalising the recently introduced continuous MERA.

For me the most exciting discovery in all of this is that there are simply an enormous number of non-gaussian states which can serve as fixed points of Wilson’s RG and give rise to very reasonable renormalisable QFTs.

An open science experiment

I gave up on open science a while ago (see this post for details). However, I’ve always wanted to give it another try.

The open-source software (OSS) movement is often held up as a model for how open science should work and it occurred to me recently we could exploit a powerful tool used in OSS to facilitate scientific collaborations, namely, github. Thus today I’d like to announce a new github-based open-science project based on the aforementioned continuum limit construction: I’ve created a github repository for this project and uploaded the latex source of a paper I’ve been working on for some time describing this construction. It is my hope that this initial incomplete draft could serve as the basis for a collaborative project on understanding how to implement Wilsonian renormalisation for tensor network states. Read the rest of this entry »


Over 6 months later

October 4, 2009

So it’s been over six months since I started this blog and I thought that this might be an appropriate moment to pause and reflect. During this time I’ve experienced several major changes culminating in a move to my new institution, the Wissenschaftskolleg zu Berlin where I’ll be a fellow for 2009/2010. These changes have been reflected in a serious lack of productivity for the past couple of months. Now that I’ve moved to Berlin and my fellowship is starting I’m hoping to reassess my involvement in open science via this blog. (And to try and restart my scientific contributions here.)

I originally started this blog for a variety of reasons, some noble, and some not so noble ;), including,

  1. I wanted to experiment with this whole science 2.0 thing in the context of a theoretical science.
  2. I wanted to silence the critics of open science (eg., by showing openness is no bad thing).
  3. I wanted to create a new venue to disseminate my research agenda.
  4. I wanted to find new collaborators and outsource (crowdsource?) expertise to solve my problems.

After 6 months or so on I feel that I am in a good position to assess how things have gone. So here goes.

1. Is there anything to this science 2.0 thing?

Yes and no: I’ve discovered some very interesting web tools to do all sorts of things which can help me to organise my scientific workflow. I really like bookmarking tools like del.icio.us. I also absolutely love tiddlywiki (although mine is sadly neglected of late); the nonlinear note-taking of tiddlywiki perfectly matches my approach to research. (I’m extremely curious to see if google wave will provide a more natural science 2.0 tool. I look forward to being able to participate when enough invites become available.)

However, I’ve discovered that other webtools (namely Twitter!!) insidiously (and seriously) fragment my concentration and free time.

(Now that I’m beginning my fellowship at the Wissenschaftskolleg I’m going to turn over a new leaf and completely shutoff internet access for several hours every day… I figure this might help me focus better.)

I’m less clear on blogging as a means of scientific outreach: I haven’t tried to seriously do this yet, but it occurs to me that this is an ideal medium.

2. On the criticisms of open science

There is one criticism of open science that I think, from my personal experience, is totally unfounded: that is the worry that people will “steal” your ideas. This certainly never happened to me over the past 6 months. I know this is a stupid argument, as I probably had nothing worth stealing etc. etc. But I also think, for other reasons, that it is an unfounded concern. Firstly, the blog posts are time stamped. Secondly, to actually steal an idea/result someone would probably have to write everything up carefully etc., and that, in itself, is hard work, which is rather unattractive. But this is all obvious.

However, this isn’t really the actual concern that critics have: the main worry that many of my colleagues express is not that someone will come and copy a solved problem from a post and make a paper, but rather that, if one was to post their favourite open problems openly, then someone else will solve them faster! Many people have expressed this concern to me.

Evidently, the currency of theoretical physics is not solved problems, but rather “solvable problems” coupled with a good intuition for how to solve them: I know lots (most?) of people who hoard interesting conjectures which are on the edge of solvability. These are the primary treasures of theoretical physics.

Open science asks you to reveal these treasures and, in the process, give up the intellectual credit for their solution; if someone quickly goes and solves the problem using your own suggested method and writes it up then all you’re likely to get in return is a citation for suggesting the problem and the argument. I have certainly experienced the frustration of posing a solvable problem and suggesting an appropriate method of solution only to find that someone else had gone and solved it using my suggested method, wrote it up, and didn’t even acknowledge our conversation.

There’s not much I can say here: I do believe this concern *is* justified. And since these treasured problems are potential papers, every time someone shares a solvable problem (+appropriate intuition for a solution) then one exposes oneself to a considerable risk of losing all credit for the potential paper.

In my experience, to first order ;), noone actually reads the scientific content on a blog. (This is pretty easily detected by looking at the blog stats, the “soft” posts always attract an order of magnitude more views.) This is natural: there are simply not many people who work in areas related to my work, and it would be presumptious to expect that everyone should read the technical posts. So the only rejoinder I can make to the criticism that sharing solvable problems is bad is that noone will read them.

3. The blog as a venue for a research agenda

Maybe. It certainly helps me: at conferences people now often know exactly what I’m thinking about and this helps conversations to start.

4. The blog as a means to find new collaborators?

No. This hasn’t helped me at all so far; I haven’t found a single new collaborator this way. Worse, most potential collaborators are quite hesitant at the prospect of having research posted online before it is complete.

Is this blog really open science?

No. I’ve had to withhold several research results from this blog. This is because of many reasons (eg. the project predated the start of the blog, my collaborators were unwilling, or I didn’t have enough time to type stuff up). So, sadly, I must confess that I’ve failed the purity test of open science…

Will truly open theoretical science ever eventuate?

My quick answer: no. Here’s why: I think we’re in a local optima which would require most scientists to simultaneously and completely change their behaviour in order to shift away from. What do I mean? As I discussed above: the currency of theoretical physics (at least) are “solvable problems+solution intuition”. If *everyone* shared there little stash of this treasures then I agree we’d live in utopian world where science would be advanced as quick as possible. Except, this global optima is unstable: all it takes is for a couple of scientists to “cheat” and hoard their solvable problems to get an edge on their colleagues and thus kick us away from this global optimum. (This is all preconditioned on papers being a metric for success in the scientific community. Yeah, I know that’s not correct but, hey, if you’ve ever sat on a hiring committee you’ll know it isn’t too far wrong.)

This is my simple intuition for why things will always stay the same. I know it’s pessimistic; but I can’t think of how to realistically create the conditions so that the global scientific optimum becomes stable. (Give increased credit to problem ideas? How?)

Where now?

I don’t know. I’ll probably go quiet again for a couple of weeks while I adjust to life here in Berlin. After that I hope to restart my research. However, I’m hoping to spend several months learning new stuff outside my area of expertise. This probably won’t produce many new results, hence, not many posts. But I’ll try and summarise my efforts here, if it fits naturally into my workflow…

Many thanks for your attention and your comments!


TiddlyWiki

March 26, 2009

I’ve just started a TiddlyWiki hosted at tiddlyspot. I’ve also added a widget for the rss feed it generates to the sidebar. Content is light right now: I’ve only written a couple of tiddlers so far. This should increase in time.

I’ve done this for a couple of reasons. Firstly, the blog medium isn’t quite right for the style of research I now do: I no longer have the luxury to think in a linear fashion about one problem for an extended amount of time (I used to). I initially thought that the blog medium would allow me to recapture this style of working. Instead, more and more, I’m thinking nonlinearly about loads of little things in parallel. (This is probably really inefficient!) It is essentially impossible to write blog posts about these little things as, without extensive work, they lack any context. My hope is that the TiddlyWiki will provide a means organise and to allow open access to these contextless chunks of microcontent.

Secondly, I can use the TiddlyWiki to put all sorts of research-related stuff online which would simply be inappropriate in a blog post, eg., a definition I want to remember, a note on an improved proof of a result in a paper, notes on a talk, etc. None of these things would warrant a blog post, but all of them could be useful to someone, somewhere. I’m encouraged that Garrett Lisi has already mastered this approach.

Thirdly, I really like the way TiddlyWiki is so easy to edit, and how it provides such a convenient non-linear way of organising stuff. I only “got” tags a couple of months ago and now I think they are absolutely essential. 

I wonder where the future lies? At the moment all these web 2.0 tools aren’t quite right for the kind of theoretical open science that I’m doing: integration isn’t smooth between all the services (essentially, unevenly implemented widgets and rss are the only way these services can talk to each other). When I collect my thoughts a bit better I might write a bit more about content integration/synchronisation between web 2.0 services.