# Category Archives: Convergence 2015

## Agreeing to disagree at the next Convergence conference

**By Hamish Johnston **

I have just returned from the Perimeter Institute (PI) in Waterloo, Canada where I enjoyed a fantastic few days immersed in discussions involving some of the sharpest minds in physics. The great and good were at the PI for the first Convergence conference and from what I have heard, the participants are calling it a great success.

But could it be even better next time?

## First image of a black hole expected a year from now

**By Louise Mayor in Waterloo, Canada**

According to Avery Broderick, a physicist at the University of Waterloo and the Perimeter Institute for Theoretical Physics (PI) in Canada, the iconic picture of a black hole from the film *Interstellar* “really only presages astronomical reality by about a year”. That’s because, as Broderick explains, “as soon as next spring the Event Horizon Telescope is gonna produce images of the black hole at the centre of the Milky Way”.

## The ins and outs of black holes and a new way of thinking about general relativity

**By Hamish Johnston**

While at the Convergence conference at the Perimeter Institute (PI), *Physics World*’s Louise Mayor and I had dinner with Sean Gryb. He did his PhD at the PI and is now doing a postdoc at Radboud University Nijmegen in the Netherlands. In the above video he shares some of his highlights of the conference.

Gryb is working on “shape dynamics”, which is a new idea for re-evaluating Albert Einstein’s general theory of relativity (GR). The idea was initiated by Julian Barbour and Gryb became involved in the development of shape dynamics while he was at PI. He now belongs to a small international band of physicists who are developing the concept. While shape dynamics is an alternative treatment of GR, the ultimate goal of their work seems to be the creation of a new framework for a theory of quantum gravity – an important goal of theoretical physics.

## Nergis Mavalvala on the upcoming Advanced LIGO run

**By Louise Mayor in Waterloo, Canada**

The search for ripples in space–time known as gravitational waves is one of my favourite scientific endeavours. So here at the Perimeter Institute’s Convergence conference, I couldn’t miss the opportunity to talk to Nergis Mavalvala, one of the speakers here.

A physicist at MIT, Mavalvala works on the Laser Interferometer Gravitational-Wave Observatory (LIGO) in the US. LIGO’s first six observing runs took place from 2002 to 2010 and yielded no detection of a gravitational wave. Since then, LIGO physicists have been working on increasing the instrument’s sensitivity – they needed to make it even better at measuring the stretching and compressing of the interferometers’ 4 km-long arms thought to occur if a gravitational wave passes through them.

Five years on, LIGO’s $200m upgrade is now complete.

## What do strange metals and black holes have in common?

**By Hamish Johnston in Waterloo, Canada**

Harvard’s Subir Sachdev has just taken the audience here at the Convergence conference on a delightful romp through the phase diagram of the cuprate high-temperature superconductors. What I found most interesting was not the superconducting phase, but rather Sachdev’s description of the “strange metal” phase.

This phase occurs when the cuprate copper-oxide layer is highly doped with holes and has perplexed physicists for some time – hence its strange moniker. It has no quasiparticles and lots of low-energy excitations so there is no easy way to describe the collective behaviour of the electrons.

## Maria Spiropulu talks about multiple Higgs beyond the Standard Model

**By Hamish Johnston in Waterloo, Canada**

Caltech’s Maria Spiropulu has a great party trick. She can demonstrate the bizarre rotational property of a spin ½ particle using a full glass of water and a contortion of her arm without spilling a drop. This was just one of the many highlights of her talk about the future of experimental particle physics that she gave yesterday at the Convergence meeting here at the Perimeter Institute.

While Spiropulu doesn’t talk about spin in the above video, she does explain why she is looking forward to analysing data from the 13 TeV run of the Large Hadron Collider, where she is part of the CMS collaboration. So, what could Spiropulu and colleagues find when they dig into the vast amounts of data that CMS is currently producing? It just could be four more types of Higgs particle. To find out more watch the video.

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## Why converge?

**By Louise Mayor in Waterloo, Canada**

Right now, top physicists from around the world are arriving in Waterloo, Canada, to attend a unique conference. Christened Convergence, the meeting is the brainchild of Neil Turok, director of the Perimeter Institute for Theoretical Physics (PI) in Waterloo, where the event will be based. I spoke to Turok to find out what motivated him to set up this conference, what makes it so special, and what he hopes it will achieve.