The Dark Side of the Universe

This month’s public lecture at the Perimeter Institute features Katherine Freese of the University of Michigan talking about ‘The Dark Side of the Universe’. By this, she means Dark Matter and Dark Energy.

Dark Matter does not give off light, so we cannot see it directly with telescopes. Yet we can tell from its gravitational effects – the way it makes stars move, the way it bends light – that it is there. It seems to be made of something different to the everyday stuff – molecules, atoms, electrons, quarks – that we know about. Astrophyical observations, sensitive experiments deep underground, and the ATLAS and CMS experiments at CERN’s Large Hadron Collider are all trying hard to get information about it - to shed some light on the Dark.

Dark Energy is something else again. The universe seems to be not only expanding, but accelerating in its rate of expansion. “Dark Energy” is just the name we have given to whatever the we-don’t-know-what is causing this.

Putting this together, the ordinary atoms that make up the known universe, from our bodies and the air we breathe to the planets and stars, constitute only 5 percent of all matter and energy in the cosmos. The remaining 95 percent is a recipe of 25 percent Dark Matter and 70 percent Dark Energy, both nonluminous components whose nature remains a mystery.

People often show pie charts to illustrate this (Freese does so in the trailer above). In an actual pork pie, Dark Energy would make up the meat, Dark Matter the pastry, and ordinary matter could be about the same proportion as that yellow jelly stuff in between them that I always used to leave on the side of my plate as a kid, but which I quite like now. All that depends a bit on the exact size and shape of pie of course.

There is more sensible, pie-free information about Freese and the talk available here. And following her talk, Freese will answer questions from the online and in-house audience – including questions submitted prior to and during the talk via Facebook and Twitter (using the hashtag #piLIVE). Questions are welcomed from everyone – aspiring scientific explorers, school classes, physics and chemistry buffs, and general science enthusiasts.

Read more https://www.theguardian.com/science/life-and-physics/2016/mar/02/the-dark-side-of-the-universe

Courtesy of Guardian News & Media Ltd