- 3352 - COMPUTER SIMULATIONS - model the universe. Year 2020 simulations of the Universe contain up to 60 trillion particles. The greatest mysteries facing astronomers and cosmologists are the roles gravitational attraction and cosmic expansion play in the evolution of the Universe.
-------------- 3352 - COMPUTER SIMULATIONS - model the universe.
- To make a computer simulation of the universe use the equations for mass and acceleration on a whole bunch of different masses moving around stars and expanding into apace and you have it. Seems simply enough.
-
- To resolve these mysteries, astronomers and cosmologists are taking a two-pronged approach. These consist of directly observing the cosmos to observe these forces at work while attempting to find theoretical resolutions for observed behaviors, such as Dark Matter and Dark Energy, which are merely theoretical but based on the evidence.
-
- In between these two approaches, scientists model cosmic evolution with computer simulations to see if observations align with theoretical predictions. The latest of which is “AbacusSummit“, a simulation suite created by Harvard-Smithsonian Center for Astrophysics (CfA).
-
- This simulation is capable of processing nearly 60,000,000,000,000 particles which is the largest cosmological simulation ever produced.
-
- Made up of more than 160 individual simulations, it models how particles behave in a box-shaped environment due to gravitational attraction. These models are known as N-body simulations and are intrinsic to modeling how dark matter interacts with baryonic (“visible”) matter.
-
- The simulations were run on the Summit supercomputer at the Oak Ridge Leadership Computing Facility (ORLCF) in Tennessee, overseen by the U.S. Department of Energy (DoE).
-
- N-body calculations, which consist of computing the gravitational interaction of planets and other objects, are among the greatest challenges facing astrophysicists today. Part of what makes it daunting is that each object interacts with every other object, regardless of how far apart they are. The more objects under study, the more interactions that need to be accounted for.
-
- To date, there is still no mathematical solution for N-body problems where three or more massive bodies are involved, and the calculations available are mere approximations. The mathematics for calculating the interaction of three bodies, such as a binary star system and a planet are known as the “Three-Body Problem” and is yet to be resolved.
-
- A common approach with cosmological simulations is stopping the clock, calculating the total force acting on each object, moving time ahead slowly, and repeating. Summit’s parallel processing power makes these multiple calculations running simultaneously.
-
- The machine learning algorithms and allowed calculations of 70 million particles per node per second at early times and 45 million particle updates per node/s at late times.
-
- Today’s galaxy surveys are delivering tremendously detailed maps of the Universe, and we need similarly ambitious simulations that cover a wide range of possible universes that we might live in.
-
- Running full simulations of N-body calculations requires that algorithms be carefully designed because of all the memory storage involved. This means that Abacus couldn’t make copies of the simulation for different supercomputer nodes to work on and divided each simulation into a grid instead. This consists of making approximate calculations for distant particles, which play a smaller role than nearby ones.
-
- It then splits off the nearby particles into multiple cells so the computer can work on each independently, then combines the results of each with the approximation of distant particles.
-
- The research team found that this approach makes better use of parallel processing and allows a large amount of the distant-particle approximation to be computed before the simulation starts.
-
- Abacus can update 70 million particles per node/second where each particle represents a clump of Dark Matter with three billion solar masses. It can also analyze the simulation as it’s running and search for patches of Dark Matter that indicate the presence of bright star-forming galaxies.
-
- Cosmology is leaping forward because of the multidisciplinary fusion of spectacular observations and state-of-the-art computing. The coming decade promises to be a marvelous age in our study of the historical sweep of the universe.
-
- Future decades will need the reviews of other reporters.
-
November 24, 2021 COMPUTER SIMULATIONS - model the universe. 3352
----------------------------------------------------------------------------------------
----- Comments appreciated and Pass it on to whomever is interested. ---
--- Some reviews are at: -------------- http://jdetrick.blogspot.com -----
-- email feedback, corrections, request for copies or Index of all reviews
--- to: ------ jamesdetrick@comcast.net ------ “Jim Detrick” -----------
--------------------- --- Wednesday, November 24, 2021 ---------------------------
No comments:
Post a Comment