Tag archives: cosmic microwave background
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
Scientists and laypeople the world over were intrigued by the announcement made by the BICEP2 collaboration earlier last month, when it claimed to have detected the primordial “B-mode polarization” of the cosmic microwave signal (CMB). Many researchers have hailed it as the first evidence for cosmic inflation – the extremely rapid expansion that cosmologists believe our universe underwent a mere 10–35 s after the Big Bang.
Indeed, after a quick search of the arXiv preprint server, I found nearly 172 papers based on the BICEP2 data that have been written since the team’s announcement on 17 March. Some 200 individual citations to the original BICEP2 paper can also be found on the server.
By Tushna Commissariat
Over the past few years, 3D printing has captured the imagination and interest of scientists and the public alike. Now, a €3 million EU-funded project known as “PERFORMANCE – PERsonalised FOod using Rapid MAnufacturing for the Nutrition of elderly ConsumErs” is adapting 3D printing technology to food in order to create easily digestible sustenance that is not only nutritious but also looks and tastes like the real thing. The proposed printer would work like its conventional inkjet counterpart – except the cartridges would be filled with liquefied food instead of ink! While that may not sound like the most appetising way of eating your five-a-day, it might come as a relief for those who suffer from a condition known as “dysphagia” that makes swallowing food difficult. You can read more about the proposed scheme on the EU’s Horizon magazine website and take a look at the video above.
By Ken Heartly-Wright
An international group of astronomers is calling for people to stop using their microwave ovens for 24 hours next April to give scientists a better chance of finding gravitational waves.
The ubiquitous kitchen gadgets broadcast copious amounts of electromagnetic radiation at frequencies around 2.45 GHz – exactly that of the cosmic microwave background, which bears the signature of gravitational waves from the early universe.
The call for a one-day global microwave oven ban comes just a fortnight after scientists detected B-mode polarization from the early universe using the BICEP2 telescope at the South Pole.
By Hamish Johnston
The big story this week is that astronomers working on the BICEP2 telescope may have spotted the first direct evidence for cosmic inflation. This is very good news for the physicist Andrei Linde, who along with Alan Guth and others did much of the early work on inflation. In the above YouTube video Linde, who is certainly in the running for a Nobel prize, receives a surprise visit from BICEP2 team member Chao-Lin Kuo. Kuo is the first to tell Linde and his wife, the physicist Renata Kallosh, the news that the theory that Linde developed more than 30 years earlier had finally been backed up by direct observational evidence. Not surprisingly, champagne glasses are clinking!
Here at physicsworld.com we have tried to tell both sides of the story: the thrill of seeing the first hints of cosmic inflation, tempered with calls for caution that more data are needed before inflation is victorious over other theories describing the early universe.
By Michael Banks
On Monday, researchers working on the Background Imaging of Cosmic Extragalactic Polarization (BICEP2) telescope at the South Pole revealed that they have detected the first evidence for the primordial B-mode polarization of the cosmic microwave background (CMB). You can read our news stories about the finding here and here.