A source to peek into what Chen's thinking about lately. http://cosmicdiscord.net/ Statistical correlation with rule of thumb, the visual way, and the mathy way - Ever since I received Daniel Kahneman’s Thinking Fast and Slow as my birthday present, it is one of my new favorite non-physics non-fiction books. It has lots of interesting points about how the mind works. As a professional from a different field but employing lots of similar methods, I can... Thu, 29 Dec 2022 00:00:00 +0000 http://cosmicdiscord.net/2022-12-29-correlations/ http://cosmicdiscord.net/2022-12-29-correlations/ The Bayesian approach - Have you ever wondered how a physicist gets convinced by a result? I sure did even before I entered physics. I’m also sure you have heard a lot of statements like “we will change our mind if we see enough evidence.” So what’s enough and how much is too much?... Wed, 28 Dec 2022 00:00:00 +0000 http://cosmicdiscord.net/2022-12-28-physics_tools_part2/ http://cosmicdiscord.net/2022-12-28-physics_tools_part2/ A quick tour to the tools we use for our daily drives, order-of-magnitude estimate - It’s been such a busy year for me. I went through the painstaking job application (perhaps worth a post in the future) in January, helped my family to recover from COVID in April, worked on a grant proposal in July, took care of my family during a medical issue in... Tue, 27 Dec 2022 00:00:00 +0000 http://cosmicdiscord.net/2022-12-27-physics_tools/ http://cosmicdiscord.net/2022-12-27-physics_tools/ So recently there was a change of policy from Slack. If your team is on a free plan, starting from Sep 1, 2022, you’ll only have access to messages in a channel within 90 days. Previously, it allows access of 10k messages regardless of the date they were sent. In... Thu, 01 Sep 2022 00:00:00 +0000 http://cosmicdiscord.net/2022-09-01-slack_migration/ http://cosmicdiscord.net/2022-09-01-slack_migration/ Introductory Lectures of CLASS the Boltzmann Solvers by Julien Lesgourgues - While house-keeping my old hard drive I found these videos. Although they are at the introductory level, and CLASS has since evolved quite a bit, they nontheless are a good starting point for students who want to try their hands at it. I hope they could give you a jump... Sun, 03 Oct 2021 00:00:00 +0000 http://cosmicdiscord.net/2021-10-03-CLASS-Boltzmann/ http://cosmicdiscord.net/2021-10-03-CLASS-Boltzmann/ A quick example of astronomical (or any type) data scraping - Dealing with astronomy data means I often need to deal with information collecting. Most of the time the API from the websites is powerful enough, I don’t need to make any extra effort to clean the data. Once in a while, I am not happy with learning all the grammar... Sun, 04 Jul 2021 00:00:00 +0000 http://cosmicdiscord.net/2021-07-04-scrapy/ http://cosmicdiscord.net/2021-07-04-scrapy/ A not-so-quick digest of the recent muon anomalous magnetic moment measurement - Now let’s continue to understand the recent g-2 result. Last time we briefly touched upon how current loops respond to an external magnetic field, and why electrons and muons fall into this category due to their spin. Now let us sketch how the value is actually related to the spin.... Wed, 05 May 2021 00:00:00 +0000 http://cosmicdiscord.net/2021-05-05-gm2_part2/ http://cosmicdiscord.net/2021-05-05-gm2_part2/ A not-so-quick digest of the recent muon anomalous magnetic moment measurement - A few of my friends asked me about the recent Fermilab results. We know that recently there is some “anomaly” going on at Fermilab, and the result is statistically significant when combined with the previous measurement from Brookhaven National Laboratory (BNL). This post will be mostly for the background. I... Wed, 07 Apr 2021 00:00:00 +0000 http://cosmicdiscord.net/2021-04-07-gm2/ http://cosmicdiscord.net/2021-04-07-gm2/ Ideas of how BSM affects (hence can be constrained by) distance measurements - Last time we talked about two types of cosmic distance. Since I am a beyond the Standard Model (BSM) junkie – so are lots of my collaborators – the next question is naturally whether New Physics could affect this type of measurements. If yes, how much can the imprint guide... Sun, 15 Nov 2020 00:00:00 +0000 http://cosmicdiscord.net/2020-11-15-cosmic_distance/ http://cosmicdiscord.net/2020-11-15-cosmic_distance/ A quick walk through of two cosmic distance measurements - Some fun facts: the Sun is one astronomical unit away, which is \(1.5\times 10^8\) kilometers away from us – that is seven zeros after 15 – or 8 minutes 19 seconds away if you travel with the speed of light; the center of the Milky Way is about 8 kpc... Sat, 15 Aug 2020 00:00:00 +0000 http://cosmicdiscord.net/2020-08-15-cosmic_distance/ http://cosmicdiscord.net/2020-08-15-cosmic_distance/ Gravitational Waves from Bose-Einstein Condensate Binaries, and why Einstein deserves big shoutout, twice. - On Feburary 11 2016, the collaboration of LIGO-Virgo, the gravitational wave interferometery facility, announced the first ever direct detection of gravitational waves in human history. The signal is from an event of two black holes merging into each other that happened about a billion years ago (1.3 billion light years... Wed, 10 Apr 2019 00:00:00 +0000 http://cosmicdiscord.net/2019-04-10-GW-BEC/ http://cosmicdiscord.net/2019-04-10-GW-BEC/