{"id":29398,"date":"2022-02-10T00:00:00","date_gmt":"2022-02-10T00:00:00","guid":{"rendered":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/?p=29398&preview=true&preview_id=29398"},"modified":"2022-03-23T13:15:04","modified_gmt":"2022-03-23T13:15:04","slug":"cutting-edge-chris-linott","status":"publish","type":"post","link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/2022\/02\/10\/cutting-edge-chris-linott\/","title":{"rendered":"Cutting edge: Chris Linott"},"content":{"rendered":"\n

How to build a Universe<\/span><\/span><\/h4>\n\n

A group of astronomers have created over 4,000 universes using computer simulations<\/p>\n\n

\"\"
Each of the CAMELS project\u2019s simulations reveals something different, in this case the variation in gas densities in a selection of model universes<\/figcaption><\/figure>\n\n

Cosmologists have it hard: creating a \u2018universe\u2019 is expensive and difficult, and even if you do manage to play God, you have to wait billions of years for the outcome of the experiment.<\/p>\n\n

The cosmologists\u2019 solution is to use powerful computers to create simulations that allow us to see what happens if you try things like changing the amount of mass in a universe.<\/p>\n\n

\u201cVarious approaches are used to solve the problem of cramming a universe\u2019s worth of physics into a code that can be run on a computer\u201d<\/p><\/blockquote>\n\n

The trouble is that it\u2019s hard to work out which bits of the Universe you can simulate. Creating a realistic view that can be compared with the images and data gathered from today\u2019s telescopes requires keeping track of processes that take place on a large range of scales, from the forces affecting the Universe\u2019s expansion to the chemistry occurring in star-forming clouds. It can be done, partly, through clever programming, but it also requires the use of a supercomputer \u2013 in the case of the CAMELS (Cosmology and Astrophysics with MachinE Learning Simulations) project, there is a massive supercomputer known as \u2018Popeye-Simons\u2019 in San Diego. With it the CAMELS researchers have created 4,233 universe simulations. For some, only the behaviour of the matter moving under gravity is followed \u2013 essentially, these are skeleton universes made only of dark matter \u2013 but for more than half of the simulations the computer has tried to follow the physics of the gas and stars too.<\/p>\n\n

Fitting it all in<\/strong><\/h5>\n\n

Each universe is different, as various approaches are used to solve the problem of cramming a universe\u2019s worth of physics into a code that can be run on a computer. But a crucial set of simulations alters the physics, either changing the density of matter in a universe simulation (how clustered it is) or altering parameters that control how efficiently supernovae and activity associated with a galaxy\u2019s central black hole pump energy into the surroundings.<\/p>\n\n

The resulting data, and the maps and simulated observations generated from it, have been made public by the CAMELS team. It\u2019ll be especially useful for observations made with ESA\u2019s Euclid telescope, which is expected to launch in 2023. Intriguingly, the team has also spent a lot of time making its virtual universes accessible to machine-learning algorithms. These can be used to simulate the work of the simulators, saving time and money by predicting what universes with properties in between those already modelled might be like.<\/span><\/p>\n\n

That opens up new angles for investigation. In the simulations, we know the true mass of a galaxy, so the team has used the CAMELS data to train an algorithm that can predict a galaxy\u2019s mass based on its properties. By turning that on the Milky Way, the team can find a new way to measure the properties of our own, real, Galaxy, from studying millions of artificial equivalents.<\/p>\n\n

The possibility of understanding how much we can say about cosmology, the behaviour of the Universe as a whole, from the study of a single galaxy is exciting. Simulations used in this way don\u2019t just provide a check on our observations, but suggest new ways we can use our telescopes.<\/p>\n\n

<\/p>\n\n

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\"\"<\/figure><\/div>\n<\/div>\n\n\n\n
\n

Prof Chris Lintott is an astrophysicist and co-presenter on The Sky at Night<\/strong>. He <\/strong>was reading\u2026 The CAMELS project: public data release <\/em>by Francisco Villaescusa-Navarro.<\/p>\n\n\n\n

Read it online at: arxiv.org\/abs\/2201.01300<\/a><\/strong><\/p>\n<\/div>\n<\/div>\n\n

Photos: ILLUSTRATION,NASA, ESA AND G. BACON (STSCI), F. VILLAESCUSA- NAVARRO\/D. ANGLES-ALCAZAR\/S. GENEL ET AL<\/p>\n","protected":false},"excerpt":{"rendered":"

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