Physicist Examines Dark Side of the Universe
Tuesday, 30 April 2019
Members of the local community joined pupils, parents and members of staff to discover more about the ‘Dark Side of the Universe’ from science communicator Dr Pete Edwards. In a fascinating address, he revealed that “most of the universe is missing” and discussed what we know, and more importantly what we don’t know, about dark matter and dark energy. He touched upon Einstein’s theory of general relativity, gravitational lensing, the cosmic microwave background and the structure of the early universe.
He began with how scientists discovered the existence of dark matter through measuring the mass of galaxies. 80% of the mass cannot be accounted for by the things we understand, such as stars, gas and dust, and is instead theorised to be made up of mysterious dark matter, which he described as “cosmic glue or scaffolding”. He encouraged the audience to try to ‘catch’ some, and estimated that one million particles of dark matter or more would have passed through everyone’s fingers in the time it took him to count to five.
Dr Edwards went on to explain that dark matter is thought to be made up of stable particles created by the Big Bang, which are now everywhere in the universe. However, these are very elusive and not something that is currently understood within science.
Talking more about the Big Bang and the expansion of the universe, he said that when he was a student the main question on everyone’s mind was, ‘What next?’ Gravity was slowing the expansion down, so scientists came up with theories of what the next stage might be. However, in the 1990s it was discovered that the expansion is speeding up again, which may be due to dark energy. However, he revealed that none of the current theories around dark energy work perfectly and that, although its effects can be seen, scientist have no way of detecting it.
Dr Edwards then talked about the Planck satellite, which in 2009 successfully measured the properties of the cosmic microwave background radiation (CMB) and gave scientists an insight into the early universe. The CMB shows the heat left over from the Big Bang, and its miniscule peaks and troughs reveal hot and cold spots in the early universe where gas clumped together and later became galaxies. He overlaid the prediction of what the CMB would look like and the image actually produced by Planck to show that they were almost identical, and concluded, “I think that is a testament to the brilliance of humans, just as impressive as Beethoven, Shakespeare or Van Gogh.”
His final comment before opening the floor to questions was to say, “The universe is made up of 5% atoms, which is the stuff we understand, 27% dark matter and 68% dark energy, which we don’t understand at all!”
The audience quizzed Dr Edwards on a range of issues relating to his talk: he was asked if he thought dark matter would ever be detectable, about the shape of a black hole, whether dark energy and dark matter will be affected if the universe ever cools to absolute zero, and also how he became interested in science. As well as answering these queries, he mentioned the opportunities available for young people in science, the importance of having young minds with fresh ideas, and that scientific advancements are driven by groups of people sharing ideas. He also stressed that science is “not just for the super-clever” and that it is possible for anyone with a passion and willingness to work hard to have a career in science.
Throughout the evening, Dr Edwards was able to explain some very complex areas of physics in an accessible way so that the whole audience was able to understand.
Dr Edwards is the Director of Science Outreach at Durham University. His talk was part of a series of Arts and Sciences Enrichment Evenings hosted each year by the Girls’ Division. Planning for enrichment events in the 2019/20 academic year is now underway: subscribe to our mailing list to receive updates and reminder emails about forthcoming Enrichment Evenings.
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