Tag archives: cosmology
By Tushna Commissariat
In case you have ever wondered why so many theoretical physicists study climate change, physicist Tim Palmer from the University of Oxford in the UK has a simple answer: “because climate change is a problem in theoretical physics”. Indeed, Palmer, who won the Institute of Physics’ 2014 Dirac medal, studies the predictability and dynamics of weather and climate, in the hopes of developing accurate predictions of long-term climate change. The answer, according to Palmer, lies at the intersection between chaos theory and inexact computing – which requires us to stop thinking of computers as deterministic calculating machines and to instead “embrace inexactness” in computing. Palmer talked about all this and more in the latest public lecture from the Perimeter Institute in Canada – you can watch his full talk above.
When someone says the word “physicist”, what image or persona comes to mind? That is the question the Institute of Physics (which publishes Physics World) was hoping to answer with its recent member survey based on diversity, titled “What Does a Physicist Look Like?” The Institute’s main aim with this diversity survey, which about 13% of its members responded to, was “to understand the profile of our members and gain some insights into who they are – diverse people with different ages, ethnicities, beliefs and much more”. You can read its entire results here.
By Tushna Commissariat in New York City, US
Although the APS March meeting finished last Friday and I am now in New York visiting a few more labs and physicists in the city (more on that later), I am still playing catch-up, thanks to the vast number of interesting talks at the conference. One of the most interesting sessions of last week, and a pretty popular one at that, was based on “20 years of quantum error correction” and I went along to the opening talk by physicist John Preskill of the California Institute of Technology. I had the chance to catch up with Preskill after his talk and we discussed just why he thinks that we are not too far away from a true quantum revolution.
Just in case you haven’t come across the subject already, quantum error correction is the science of protecting quantum information (or qubits) from errors that would occur as the information is influenced by the environment and other sorts of quantum noise, causing it to “decohere” and lose its quantum state. Although it may seem premature that scientists have been working on this problem for nearly two decades when an actual quantum computer has yet to be built, we know that we must account for such errors if our quantum computers are ever to succeed. It will be essential if we want to achieve fault-tolerant quantum computation that can deal with all sorts of noise within the system, as well as faults in the hardware (such as a faulty gate) or even a measurement.
Over the past 20 years, theoretical work in the field has made scientists confident that quantum computing of the future will be scalable. Preskill says that “it’s exciting because the experimentalists are taking it quite seriously now”, while initially the interest was mainly theoretical. Previously, scientists would artificially create the noise in the quantum systems that they would correct but now actual quantum computations can be fixed. Indeed, Preskill says that one of the key things that has really moved quantum error correction along in the past few years is the concentrated improvement of the hardware used, i.e. better gates with multiple qubits being processed simultaneously.
By Matin Durrani
Happy new year and welcome back to Physics World after the Christmas break.
It’s always great to get a new year off to good start, so why not tuck into the first issue of Physics World magazine of 2016, which is now out online and through the Physics World app.
Our cover feature this month lets you find out all about the Planck mission’s new map of the cosmic microwave background. Written by members of the Planck collaboration, the feature explains how it provides information on not just the intensity of the radiation, but also by how much – and in which direction – it’s polarized.
By Tushna Commissariat
So much has been said about Einstein and his general theory of relativity (GR) that one would assume there isn’t two entire days worth of talks and lectures that could shed new light on both the man and his work. But that is precisely what happened last weekend at Queen Mary University London’s “Einstein’s Legacy: Celebrating 100 years of General Relativity” conference, where a mix of scientists, writers and journalists talked about everything from the “physiology of GR” to light cones and black holes, to M-theory and even GR’s “sociological spin-offs”.
The opening talk, “Not so sudden genius”, was given by journalist and author of “Einstein: A hundred years of relativity“, Andrew Robinson. The talk was very fascinating and early on Robinson outlined that Einstein stood on the shoulders of many scientists and not just “giants” such as Newton and Mach. But he also acknowledged that the scientist was always a bit of a loner and he preferred it this way. Robinson rightly pointed out that until 1907, Einstein was “working in brilliant obscurity” and later, even once fame found him, rootlessness really suited Einstein’s personality – he described himself as “a vagabond and a wanderer”.
By Tushna Commissariat
As readers of Physics World, you probably don’t need me to tell you that this year marks 100 years since legendary physicist Albert Einstein laid the foundations for his revolutionary general theory of relativity (GR). This month marks the exact time when he began giving a series of four weekly lectures – the first of which was on 4 November 1915 – to the Prussian Academy of Sciences in Berlin. Indeed, today is the centenary of the final lecture, when he presented his “Field equations of gravitation”. In the video above, philosopher and one-time physicist Jürgen Renn, from the Max Planck Institute for the History of Science in Berlin, gives a short and sweet explanation of GR and its impact on physics.
By Tushna Commissariat
Here at Physics World, we enjoy a good debate and late last week, a paper appeared on the arXiv server that is bound to kick up quite the storm, once it has been peer-reviewed and published. Titled “Marginal evidence for cosmic acceleration from type Ia supernovae”, the paper was written by Subir Sarkar of the Particle Theory Group at the University of Oxford and the Niels Bohr Institute in Copenhagen, together with colleagues Alberto Guffanti and Jeppe Trøst Nielsen. It suggests that the cosmic expansion may not be occurring at an accelerating rate after all, contrary to the findings of previous Nobel prize-winning work and most of our current standard cosmological models, including that of dark energy.
Indeed, the researchers’ work suggests that the evidence for acceleration is nowhere near as strong as previously suggested – it is closer to 3σ rather than 5σ, and allows for expansion at a constant velocity. Nielsen et al. have come to this conclusion after studying a much larger database of type Ia supernovae – 50 of which were studied in the original work, while this study looks at 740 – that are used as “standard candles” to detect cosmic acceleration.
This study is sure to make many cosmologists sit up and take notice, and an interesting discussion is sure to follow. So watch this space and check back in with us, once the paper is published and we catch up with Sarkar and his colleagues.
By Tushna Commissariat
It’s not often that physics, or indeed a physicist, has much in common with pop music or exceedingly popular boy bands. But earlier this week, at an event at the Sydney Opera House titled “An Evening with Stephen Hawking, with Lucy Hawking and Paul Davies”, an audience member asked Hawking (who appeared in holographic form) “What do you think is the cosmological effect of Zayn Malik leaving One Direction?” Watch the video above to see what Hawking said to comfort the distraught fan and how theoretical physics truly may have all the answers.
By Matin Durrani
A couple of years back, I had the pleasure of travelling 1100 metres below ground to visit a dark-matter laboratory at the bottom of the Boulby Mine on the north-east coast of England. The journey was certainly memorable – it involved plunging down in a rattling lift cage for several minutes with a group of miners setting off on their morning shift. Once in the lab – housed inside a souped-up set of trailers – I interviewed physicist Sean Paling about the experimental projects going on there.
Setting up an underground lab, like that at Boulby, certainly doesn’t come cheap and in recent years, many have started to diversify into new areas. In the May issue of Physics World, which is now out in print and digital formats, Paling and his colleague Stephen Sadler – who is director at DURRIDGE UK Radon Instrumentation – describe the renaissance in the science taking place far beneath our feet. Studies in underground labs now range from Mars rovers to muon tomography and from radioactive dating to astrobiology.
By James Dacey
Astronomers believe they may finally be able to explain the origin of the “cold spot”, a glaringly large cool region in the cosmic microwave background (CMB). Maps of the CMB, such as that created by the Wilkinson Microwave Anisotropy Probe (WMAP) and more recently by the Planck mission, reveal the distribution of radiation left over after the Big Bang. When in 2004 researchers noticed this cold spot on the map, they soon realized it was either a sign of exotic physics linked to the Big Bang itself or it was caused by some sort of structure in the foreground between the CMB and the Earth.
Pioneering women of physics, why you should become a particle physicist and a BICEP2 scientist on all that dust
By Hamish Johnston
Over on the Quantum Diaries blog, Aidan Randle-Conde has put together a lovely photo-essay called “30 reasons why you shouldn’t be a particle physicist”. It is reverse psychology, of course, and the 30 images highlight the benefits of devoting your life to studying sub-atomic particles. As someone who chose to do condensed-matter physics, do I now think that I made a huge mistake? No, but I have shared the thrill and excitement of being at CERN when the Higg’s was discovered and seen the Large Hadron Collider and its detectors up close, so I know where he is coming from.