Dark Matter Lecture
Dark Matter Lecture
On Wednesday the 20th September, Physics A Level students, as well as GCSE students interested in pursuing a career within physics were invited to attend a lecture at St Philomenas on dark matter by a physicist from the University of Royal Holloway in Egham. One of the presenters was a researcher in the field of neutrinos and dark matter. He discussed with us what dark matter is, and how they are trying to prove its existence. Although scientists don’t yet know what dark matter is, there is definitive proof of the existence of dark matter as early scientists from the 20th century such as Fritz Zwicky found that, through studying the coma cluster. He used the luminosity of galaxies and their distance from the Earth to measure their masses. He found that each galaxy had masses that were by 400 time greater than they should be. This suggested that there was something creating mass but not emitting light – dark matter!
Evidence by an American female scientist called Vera Rubin later suggested that this theory was correct. Her studies showed that there is five times more dark matter in the universe then there is normal matter, which helps explain mass of galaxies was so much heavier than that predicated by scientists previously.
The visiting physicist also talked to us about all the major experiments in which he took part in order to prove the existence of dark matter. The most interesting was one that took place underground in active mines in Canada, a place that is considered to be the least radioactive place in the world. In this experiment they used liquid argon encased in acrylic with strong sensors surrounding it, in order to detect the small amounts of dark matter found within our atmosphere. The researcher said that on average, one particle of dark matter passes through a tea cup each time you drink one. This is quite a large number in comparison to the thousands of ordinary matter particles which pass through us each second! Overall, we found this experience very informative and it sparked our interest in the field.
By Clara and Christina, Year 12 A Level Physics students