International Dark Matter Day

Jessica Copeland describes International Dark Matter Day 2017, celebrated by Royal Holloway’s Physics Department, and the theories behind Dark Matter.

On Monday 30 October, the Physics Department at Royal Holloway celebrated International Dark Matter Day 2017 with an evening of events. The event was hugely attended, with more than 500 people registered online and Windsor Auditorium packed for the evening’s first event, a lecture given by Dr Jocelyn Monroe.

With dark matter now estimated to make up a quarter of the matter in the universe, the theory was first proposed in the 1930s when the observed rotation speeds of nearby galaxies was found to be too fast to account for the visible mass of the stars and planets them. Confirmation of its existence came in the Cosmic Microwave Background in the 2000s and even more recently in observations of gravitational lensing – where light in bent around some huge invisible mass and a magnified image can be seen. However, as of yet there is no clear phenomena that can be called Dark Matter; we can only see its effects. However, there are some strong candidates including sterile neutrinos – a particle so unresponsive it would take the entire age of the universe to observe even one interaction – or axions – particles first proposed to solve a strong force problem in the 1970s.

In her lecture, Monroe discussed her research into a primary candidate, WIMPs, a theoretical weakly interacting particle that might give rise to Dark Matter. It would have low velocity in comparison to the speed of light; low mass similar to that of the proton and be uncharged. This all leads to problems in detection as it hardly interacts with itself, light or matter around it. and the problems there are in trying to detect a particle that hardly interacts.

With dark matter now estimated to make up a quarter of the matter in the universe, the theory was first proposed in the 1930s when the observed rotation speeds of nearby galaxies was found to be too fast to account for the visible mass of the stars and planets them.

The floor was opened up to questions from the audience, which concerned the applications of dark matter in new technologies (we just don’t know yet), where it might have originated from and the difference from dark energy – a theory to explain the accelerating expansion of the universe and estimates give that it makes up nearly 70% of the energy in the universe .

“It was truly exciting hosting a Dark Matter lecture on the occasion of the International Dark Matter Day!” said Anna Christodoulou, SEPNet Outreach Officer for Royal Holloway and organizer of the event. ”Professor Jocelyn Monroe gave a very interesting lecture to a 300 people audience and unraveled the exciting research taking place at Royal Holloway. Our group participates in international collaborations (DEAP, SNOLAB) and we just got a new Dark Matter Time Projection Chamber.”

The evening concluded with guided tours of the department’s laboratories and astrodome; a live connection with the DEAP experiment at SNOLAB in Canada, where they are trying to observe dark matter interactions in liquid argon in a former mine deep underground.

To find out more, visit: https://www.darkmatterday.com/ and https://www.symmetrymagazine.org/article/what-could-dark-matter-be .

Look out for the forthcoming Christmas Physics Lecture: Using Machine Learning at the Large Hadron Collider given by Professor Glen Cowan on the 8th December. For further details and to book a place, visit: https://www.royalholloway.ac.uk/physics/events .