| AskScience AMA Series: We are Cosmologists, Experts on the Cosmic Microwave Background, Gravitational Lensing, the Structure of the Universe and much more! Ask Us Anything! Posted: 04 Sep 2020 04:01 AM PDT We are a bunch of cosmologists from the Cosmology from Home 2020 conference. Ask us anything, from our daily research to the organization of a large conference during COVID19! We have some special experts on - Inflation: The mind-bogglingly fast expansion of the Universe in a fraction of the first second. It turned tiny quantum fluctuation into the seeds for the galaxies and clusters we see today
- The Cosmic Microwave background: The radiation reaching us from a few hundred thousand years after the Big Bang. It shows us how our universe was like, 13.4 billion years ago
- Large Scale Structure: Matter in the Universe forms a "cosmic web" with clusters, filaments and voids. The positions of galaxies in the sky shows imprints of the physics in the early universe
- Dark Matter: Most matter in the universe seems to be "Dark Matter", i.e. not noticeable through any means except for its effect on light and other matter via gravity
- Gravitational Lensing: Matter in the universe bends the path of light. This allows us to "see" the (invisible) dark matter in the Universe and how it is distributed
- And ask anything else you want to know!
Answering your questions tonight are - Alexandre Adler: u/bachpropagate PhD student at Stockholm University. Systematics for cosmic microwave background polarization experiments (Spider, Simons Observatory, Litebird) and CMB data analysis. Twitter: @BachPropagate.
- Alex Gough: u/acwgough PhD student: Analytic techniques for studying clustering into the nonlinear regime, and on how to develop clever statistics to extract cosmological information. Previous work on modelling galactic foregrounds for CMB physics. Twitter: @acwgough.
- Arthur Tsang: u/onymous_ocelot Strong gravitational lensing and how we can use perturbations in lensed images to learn more about dark matter at smaller scales.
- Benjamin Wallisch: Cosmological probes of particle physics, neutrinos, early universe, cosmological probes of inflation, cosmic microwave background, large-scale structure of the universe.
- Giulia Giannini: u/astrowberries PhD student at IFAE in Spain. Studies weak lensing of distant galaxies as cosmological probes of dark energy.
- Hayley Macpherson: u/cosmohay. Numerical (and general) relativity, and cosmological simulations of large-scale structure formation
- Katie Mack: u/astro_katie. cosmology, dark matter, early universe, black holes, galaxy formation, end of universe
- Robert Lilow: (theoretical models for the) gravitational clustering of cosmic matter. (reconstruction of the) matter distribution in the local Universe.
- Robert Reischke: /u/rfreischke Large-scale structure, weak gravitational lensing, intensity mapping and statistics
- Shaun Hotchkiss: u/just_shaun large scale structure, fuzzy dark matter, compact object in the early universe, inflation. Twitter: @just_shaun
- Stefan Heimersheim: u/Stefan-Cosmo, 21cm cosmology, Cosmic Microwave Background, Dark Matter. Twitter: @AskScience_IoA
- Tilman Tröster u/space_statistics: weak gravitational lensing, large-scale structure, statistics
- Valentina Cesare u/vale_astro: PhD working on modified theories of gravity on galaxy scale
We'll start answering questions from 19:00 GMT/UTC on Friday (12pm PT, 3pm ET, 8pm BST, 9pm CEST) as well as live streaming our discussion of our answers via YouTube. Looking forward to your questions, ask us anything! submitted by /u/AskScienceModerator [link] [comments] |
| How can a radiating body be in equilibrium with its environment? Posted: 04 Sep 2020 02:21 AM PDT The Black Body Radiation article on Wikipedia says: "Black-body radiation is the thermal electromagnetic radiation within or surrounding a body in thermodynamic equilibrium with its environment, emitted by a black body (an idealized opaque, non-reflective body)." If equilibrium means there is no net transfer or matter or energy, how does a black body radiate anything? The article also describes how the spectra of lava, fire and heated steel can be used to approximate their temperatures. All these seem to have a net transfer of energy into their surroundings, heating the air around them. submitted by /u/miscalibrated [link] [comments] |
| How to distinguish between an unstable atom and an element with a very short half-life? Posted: 03 Sep 2020 06:13 PM PDT Oganesson, the current last element of the periodic table, has a half-life of merely 0.89 milliseconds. Are there other standards that deem it to be a genuine element instead of a bunch of stuff forcibly bound together? submitted by /u/crescentpieris [link] [comments] |
| Do we have any predictions or models that show how many more people in the US would have died if we hadn’t gone on lockdown? Posted: 04 Sep 2020 05:45 AM PDT |
| How consistant is the spread of elements in the milky way? And what impact might that have on development of intelligent life? Posted: 04 Sep 2020 05:14 AM PDT I'm wondering how common a scenario might be whereby intelligent life evolves on a planet but they lack the elements/materials to progress through an industrial evolution. Such a civilisation would be unable to leave their home world and might be an explanation as to why we haven't detected any alien civilisations yet. Or is it the case that most star systems start off with roughly the same stuff? submitted by /u/andymilnedb10 [link] [comments] |
| When Pangea was the only one continent, were there big islands built by volcano like Hawaii around the world? Posted: 03 Sep 2020 09:07 AM PDT |
| How do we know how many stars are in our galaxy or any other? Posted: 03 Sep 2020 09:50 AM PDT I assume the estimate of 250B +/- 150B stars in the milky way is extremely rough, but it seems to be based on something. What is that estimate based on? Do we chop galaxies into cubes and count the stars per cube, or maybe use cosmological principles, or other observable facts like the gravitational influence or output of different types of electromagnetic radiation of a galaxy to infer star count? If so, how, and what else do we do? submitted by /u/Veridically_ [link] [comments] |
| Is it possible to tell the shape of a piece of metal from the sound it makes when stuck? Posted: 03 Sep 2020 11:36 PM PDT More wondering if that information is transmitted in the sound, and if with infinite precision, could it be done. Obviously this would be nearly impossible by hand. submitted by /u/Skrtmvsterr [link] [comments] |
| If Photons are massless particles, does this mean Photons don’t interact with the Higgs field? Posted: 03 Sep 2020 08:23 PM PDT |
| When people say smokers have many more nicotine receptors in the brain than non-smokers, what does this exactly mean and why is it bad? Posted: 03 Sep 2020 11:27 PM PDT |
| How do flies walk on the ceiling? Posted: 03 Sep 2020 11:23 PM PDT |
| Are Redshift/Blueshift used to determine which way a star is traveling? How can we know when one is happening instead of the other? Posted: 03 Sep 2020 05:32 PM PDT I understand the Doppler effect and how Redshift and Blueshift happen, but I don't understand, when we observe a star, how we can know when we're observing the result of one vs the other (or neither). submitted by /u/SteveTCook [link] [comments] |
| Does having friends in your learning enviornment help you learn better? Posted: 04 Sep 2020 01:10 AM PDT |
| Can tectonic plates fuse and become one? Posted: 03 Sep 2020 07:35 AM PDT I am trying to create a fictional world, and the first thing I did was start with a planet and plate boundaries. I have an idea of what my continents will look like, one of which is in the middle of the plate, but has a mountain range. Instead of putting an active plate boundary there (i.e Indian subcontinent), I was thinking that this range is a result of two plates coliding in the distant past and then fusing into one plate. My question is, how realistic would it be to have two plates collide and fuse into one? Is it possible for a plate boundary to go extinct leaving a mountain range that is slowly eroding? Is there a such thing as an ancient plate boundary? Any help would be appreciated. submitted by /u/kgabny [link] [comments] |
| How does the nerve agent Novichok work? Posted: 03 Sep 2020 08:59 AM PDT So, this poison has been in the news quite a bit after the poisoning of Viktor Skripal in 2018 and now again after Alexander Navalny suffered a similar fate. Now I, with my grant total of zero knowledge with regards to both poisons and intelligence work, have been wondering how in both cases the victims were able to survive the attack. Are the Russians just bad at their jobs? Or were they some unforeseen circumstances that enabled Skripal and Nawalny to survive? Or is it something with regards to how the poison works? submitted by /u/Ahrix3 [link] [comments] |
| How do cells in a multicellular organism stick together and how do they know which cells to stick to? Posted: 03 Sep 2020 02:15 AM PDT |
| Which causes more changes in the Earth's seasons? Nutation or precession? Posted: 03 Sep 2020 12:12 PM PDT |
| Why do volatile acids like butyric acid have pungent odours even though their boiling points are well over 100C? Posted: 03 Sep 2020 12:09 PM PDT I came across a mixture of volatile acids that includes acetic, formic, and butyric acids. It smells gross. Why can I smell these things so readily even though all of the components in the mixture have boiling points higher than water and are therefore not 'volatile' in the traditional sense like, say, ethyl ether (boiling point 35C)? submitted by /u/own0dog [link] [comments] |
