Cosmology on IanHuston.net

New London Institute of Cosmology

Thu, 08 Nov 2012 13:19:52 +0100

At a London Cosmology Discussion Meeting last week, representatives of the London cosmology groups discussed ways of increasing collaboration and cooperation between the groups and how to utilize the various skills in London in a more coherent way. One of the main outcomes of this meeting was a consensus to form a ‘virtual’ institute to act as an umbrella organisation for the collaboration efforts. This London Institute of Cosmology would initially act as a clearing house for event information, especially seminars in the groups, information about research visitors to London, and provide a structure for possible funding applications.

Trispectrum during Inflation

Tue, 03 Apr 2012 15:05:19 +0100

After a lot of work, “Large trispectrum in two-field slow-roll inflation” was released on the arXiv yesterday as arXiv:1203.6844. In this article Joe Elliston, Laila Alabidi, David Mulryne, Reza Tavakol and I look at the generation of higher order statistics during inflation in the early universe. In the early universe the curvature perturbations, which later are seen as temperature fluctuations in the Cosmic Microwave Background (CMB), are initially thought to be Gaussian, but can become skewed during inflation depending on the physics of their evolution.

Two new papers on the arXiv

Mon, 05 Dec 2011 18:11:23 +0100

Last Tuesday was a bit hectic for me as I tried to coordinate the last minute changes needed to put two papers on the arXiv servers for the next day. The two articles which are now available are numbered 1111.6919 and 1111.6940: Calculating Non-adiabatic Pressure Perturbations during Multi-field Inflation Ian Huston, Adam J. Christopherson Abstract: Isocurvature perturbations naturally occur in models of inflation consisting of more than one scalar field.

Outreach lecture to teachers

Thu, 21 Jul 2011 15:39:35 +0100

I gave a lecture to secondary school teachers this week as part of the Goldsmith’s Company’s Science for Society Course on astrophysics. Having heard about the Big Bang model and some of its problems from my colleague Dr David Mulryne, I was given the task of outlining how the inflationary paradigm tries to solve these problems and some of the reasons we think it is a good model of the early universe.

New paper and Pyflation software package

Mon, 07 Mar 2011 12:31:02 +0100

My latest paper has just hit the arXiv and is now available. The paper builds on the numerical work I previously completed on cosmological perturbations beyond linear order. The new results do not assume slow-roll in the calculation of the source term for the second order equations of motion and so allow a much greater range of potentials to be analysed. The paper is called “Second Order Perturbations During Inflation Beyond Slow-roll” and already has a record on SPIRES and Inspire Beta.

Durham UK Cosmo meeting

Wed, 08 Sep 2010 19:23:14 +0100

Durham University, and in particular the Institute for Particle Physics Phenomenology hosted the annual two-day UK Cosmology meeting this year. There were lots of very interesting talks, and I hope to give a flavour of some of the issues that were mentioned over the course of the meeting. The list of participants and the programme outline are on the Durham website, however I do not expect the slides of the talks to be uploaded except perhaps by individual speakers.

Thesis now online

Tue, 06 Jul 2010 15:35:29 +0100

I passed my viva examination a few months ago, and after very helpful suggestions from my two examiners I submitted the final version of my PhD thesis to the QMUL authorities a month ago. The paperwork all went through so I have now completely finished my doctoral training. All that remains to be done is the celebratory donning of a floppy cloth cap and scarlet robes at the graduation ceremony in a few weeks.

Relativity and Cosmology Seminar

Thu, 25 Mar 2010 14:39:08 +0100

Yesterday I gave my first seminar as a postdoc in the regular Relativity and Cosmology series at QMUL. People seemed to engage with the material and there were quite a few questions at the end. The slides for the talk are available as a pdf or through the embedded widget below. My style for talks is heavily skewed towards minimalist slides with lots of verbal explanation so without having me beside you to guide you through them they might be hard to understand.

Next UK Cosmo meeting

Mon, 15 Feb 2010 16:58:46 +0100

The next UK Cosmology meeting is taking place in Lancaster on the 24th February. These meetings provide an opportunity to find out what other cosmologists around the country are doing and to establish and cement working relationships. The deadline for registering your interest in attending or giving a talk is tomorrow the 16th. Funding is being provided for travel costs and PhD students and postdocs are especially encouraged to apply to speak.

New QMUL Cosmology Wiki

Mon, 18 Jan 2010 18:59:09 +0100

The Cosmology and Relativity Group in Queen Mary (where I work) have recently opened a new wiki to replace the old group pages which were rarely updated. Only group members are able to add and edit content but hopefully there is some useful information for anyone interested in the group.

Cosmo09 roundup

Thu, 17 Sep 2009 21:48:35 +0100

The Cosmo09 conference took place last week in the picturesque surroundings of CERN with lots of talks, a lot of conversation and not a little French/Swiss beer. Videos of the plenary talks are now available and the slides of every talk (including the parallel sessions) are listed in the conference programme for each session. There are a few personal notes on the sessions in the FriendFeed group. My talk was on Thursday afternoon in the inflation session.

Cosmo09 conference

Tue, 01 Sep 2009 15:37:59 +0100

The annual Cosmo conference for all branches of cosmology is taking place next week 7th-11th September in CERN. I will be attending and giving a talk in the inflation session on Thursday afternoon. After last week’s Science Online London 2009 conference which I attended, I have been thinking about how to get fellow cosmologists to start interacting online. I am not sure whether anyone else will use it but I have started using the hashtag #cosmo09 on twitter and have created a FriendFeed room for the conference.

Numerical Calculation of Second Order Perturbations

Thu, 23 Jul 2009 16:30:43 +0100

My new paper, written with Karim Malik, has just been released into the wild. We show that it is possible to numerically simulate second order perturbations for a single scalar field with a canonical action. I’ve been working on this for a long time and learned a lot about the mechanics of inflation in the process. I’ve also churned out quite a lot of python code, and learned some rudimentary parallel programming.

New tools for a new year

Thu, 11 Oct 2007 16:44:34 +0100

As the new semester is starting in earnest, I think it’s time for me to post the first update for a few months. One of the main differences between post-graduate and under-graduate life is that as postgrads we don’t have a 3 month break over the summer. As seminars finish at the same time as lectures, the summer months can be more productive as long as you don’t get distracted by the summer sunshine.

Post talk and pre trip

Wed, 04 Jul 2007 17:21:13 +0100

My talk in Portsmouth was on Tuesday of last week, and with the exception of a bit of trouble with the train on the way down, it seemed to go well enough. I didn’t run wildly over time or commit any other glaring mistakes, but did get a bit of a grilling in the question session. I suppose I need some practice on how to deal with problem questions, in which an answer can’t or shouldn’t be attempted in a short space of time.

First talk imminent

Wed, 20 Jun 2007 16:41:09 +0100

So it turns out that I am going to give a talk at UK Cosmo next week. It’s only supposed to be 18 minutes long, which you might imagine wouldn’t be that difficult to put together, but as you can tell from the lack of posts here recently, I’ve been having some problems. The talk is supposed to be based on our last paper (which will soon appear in JCAP by the way), but with limited time I think I will have to speed through it pretty quickly.

The End of Cosmology

Wed, 06 Jun 2007 12:58:15 +0100

Here in Queen Mary, we hold a discussion group every Wednesday during term time. The paper we are discussing this afternoon is a recent essay by Lawrence Krauss and Robert Scherrer, which has been causing a bit of a stir in cosmology circles, both in the blogosphere and the real world. The essay won 5th prize in the annual Gravity Research Foundation Essay Competition which always features some interesting reading material.

UK Cosmology Dates

Wed, 30 May 2007 13:18:29 +0100

The next UK Cosmo meeting has just been announced and will take place in Portsmouth on the 26th of June. The local website has details about how to register to attend or give a talk. There is no confirmed venue yet but keep an eye on the site for more information and travel details. The UK Cosmo meetings are always well attended, and feature a wide range of topics with researchers from all over the UK.

New Dark Matter evidence

Tue, 15 May 2007 16:03:11 +0100

NASA is holding a press conference today in which new evidence for the existence of dark matter will be presented. There will be an audio feed and graphics on the web as soon as the conference starts. A comment at the Angry Physicist’s blog links to the abstract of the upcoming APJ paper which describes this “dark ring”: The mass reconstruction of CL0024+17 obtained in such a way is remarkable. It reveals a ring-like dark matter substructure at r 75"

Multiverses and Super-Turtles

Fri, 04 May 2007 16:16:50 +0100

Last night’s talks were really interesting and it was good to get three different opinions being discussed in a (semi-)public setting. Usually these sort of lectures are one-sided in their opinions, which tends to hide the fact that the hot topics are also the most controversial. So as I mentioned earlier there were three speakers, Bernard Carr, George Ellis and Paul Davies. On the night Chris Isham was not able to attend, so one of the representatives of the Templeton Foundation acted as chairperson.

Bernard introduced the idea of the multiverse, after having plugged the new book and thanked all the contributors. With only thirty minutes allotted to each speaker there wasn’t enough time for a detailed explanation, but he explained some of the different multiverse ideas, in particular using this picture by Max Tegmark to illustrate the hierarchy of multiverse structures. With time running out (and some quite surprising heckling when he asked for some leeway), Bernard had to race through the history of physics on one slide, imploring us to consider it as “an artistic journey”.

First paper on the arXiv

Thu, 03 May 2007 14:29:26 +0100

[Shameless plug of my own work alert!] So today I finally became a ‘proper’ scientist and saw my name on the listings of the arXiv. Our new paper, Gravitational Wave constraints on DBI inflation, makes life difficult for the usual DBI brane inflation models by specifying some pretty strong limits on their existence, depending on the size of the scalar tensor ratio. In a nutshell, if gravitational waves from the CMB are observed, these models will have a hard time surviving.

Universe or Multiverse?

Wed, 02 May 2007 11:39:59 +0100

On Thursday evening I am going to the launch of this book, edited by Professor Bernard Carr from QMUL, called “Universe or Multiverse?”. It is a collection of articles about the idea of a multiverse and the prospects (if any) or ever experimentally verifying it. On the night of the launch there are going to be three speakers, Bernard himself, Paul Davies and George Ellis, with Chris Isham chairing. Unfortunately the event is by invitation only and is now fully booked.

Questioning the Big Bang

Mon, 30 Apr 2007 17:36:54 +0100

Sean Carroll has a long post at Cosmic Variance, talking about the usual explanations of early universe physics, and why there are some good reasons to question these ideas. All the currently fashionable (and not-so-fashionable) ideas are discussed, with some good explanations for those, like me, who are not up to speed with all the myriad theories. It is a long article, with a long discussion in the comments section as well, but well worth the effort if you want to know about the current trends.