Physics
This is a big page of links, some with brief explanations, divided into a few rough categories.
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Tools • Fluid Dynamics • Politics • Astronomy • Gravitation • More
Tools for Physics
VegaLite.jl: Julia bindings to Vega-Lite: “VegaLite.jl is a plotting package for the julia programming language. The package is based on Vega-Lite, which extends a traditional grammar of graphics API into a grammar of interactive graphics.”
Visualize real-time data streams with Gnuplot: “For the last couple of years, I’ve been working on European Space Agency (ESA) projects […] In the ESA project I am currently working on, I am also the technical lead; and I recently faced the need to (quickly) provide real-time plotting of streaming data. […] Gnuplot follows the powerful paradigm that UNIX established: it comes with an easy to use scripting language, thus allowing its users to prescribe actions and ‘glue’ Gnuplot together with other applications - and form powerful combinations. […] it took me 30min to code this, and another 30 to debug it. Using pipes […] we are able to do something that would require one or maybe two orders of magnitude more effort in any conventional programming language (yes, even accounting for custom graph libraries - you do have to learn their API”.
Jupyter: notebooks for education and collaboration: My article on the browser-based interface to Python and more in LWN.
The 100 billion frames per second camera that can image light itself: Detailed attempt to describe how the imaging system works.
Abramowitz & Stegun is now an iOS App: ‘The classic Handbook of Mathematical Functions, edited by Milton Abramowitz and Irene Stegun, now available on your iPhone or iPad.’ Having this heavy book on my shelf is making me feel old. The next generation of graduate students will scarcely believe that we heaved this thing over to our desks to flip through the pages.
WebPlotDigitizer: Have a plot but need the numbers? This web service can take care of it. Reminds me of the ancient Macintosh program “Datathief.”
Comparison of plotting packages: Newcomers (and others!) using Julia can be bewildered by the profusion of options for making plots and visualizations. Chris Rackauckas provides a useful summary of the pros and cons of all the major packages.
gnuplot: Gnuplot news and information.
SciPy: “SciPy (pronounced ‘Sigh Pie’) is a Python-based ecosystem of open-source software for mathematics, science, and engineering.”
Plotting tools for Linux: matplotlib: My article introducing matplotlib, the plotting library for Python.
PhysicsJS - A modular, extendable, and easy-to-use physics engine for javascript: Several impressive demos.
Fortran Standard Library: This is an interesting development.
New features in gnuplot 5.4: My article appeared today in LWN. I take a look at five major new capabilities in gnuplot, including voxel plotting, for visualizing 3D data.
JupyterLab: Ready for Users: My article on the evolution of the Jupyter Notebook in LWN.
SciPy Reaches v. 1.0: My article about the Python scientific library in LWN.
Diverging Color Maps for Scientific Visualization (Expanded): Shows how the commonly used rainbow palette is a bad choice for visualization and how to generate palettes with better perceptual properties, that are also better for colorblind viewers.
Lazy Physics (and Clojure): Processing time series data from particle physics experiments using Clojure’s lazy sequences.
Gnuplot v6 comes with pie: My article about the gnuplot v6 release appeared today in LWN.
All about Modelica: “Modelica is a great tool for modeling cyber-physical systems, for example to study the fuel efficiency of an hybrid vehicle, or to evaluate the interactions between renewable energy sources and the electrical grid. “In this post I will provide a general overview on Modelica, and I’ll showcase some of its main features.”
HTML5 Canvas Fluid Simulation: A Navier-Stokes solver in the browser.
If you grew up on some form of classic fortran and need to be jolted into the 21st century, here is a good place to start.
Fluid dynamics
Statistical and Numerical Investigations of Fluid Turbulence: Contains clear introductions to several topics in turbulence; a well-written thesis.
Flow visualization: “This site is devoted to a course for mixed teams of engineering and fine arts photography and video students at the University of Colorado. In this course, we explore a range of techniques for creating images of fluid flows. Our work is motivated not just by the utility and importance of fluid flows, but also by their inherent beauty.”
The real butterfly effect and maggoty apples: A fascinating look at the limits of determinism in classical physics.
Long exposure of fog flow: Several minutes under moonlight; a study in fluid flow that is also a lovely photograph.
Analytical Vortex Solutions to the Navier-Stokes Equation: This Ph.D. thesis contains a lot of useful work.
Reproducible and replicable CFD: it’s harder than you think: The authors find that even changes in linear algebra library versions cause a failure or replication of their CFD results.
Weakly nonlinear incompressible Rayleigh–Taylor–Kelvin–Helmholtz instability in plane geometry: “A weakly nonlinear theoretical model is established for the two-dimensional incompressible Rayleigh–Taylor–Kelvin–Helmholtz instability (RT–KHI).”
Oceananigans.jl: Fast and friendly geophysical fluid dynamics on GPUs: “Oceananigans.jl is a fast and friendly software package for the numerical simulation of incompressible, stratified, rotating fluid flows on CPUs and GPUs. Oceananigans.jl is fast and flexible enough for research yet simple enough for students and first-time programmers. Oceananigans.jl is being developed as part of the Climate Modeling Alliance project for the simulation of small-scale ocean physics at high-resolution that affect the evolution of Earth’s climate.”
Oceananigans.jl: 
“Fast and friendly fluid dynamics on CPUs and GPUs”
“Fast and friendly fluid dynamics on CPUs and GPUs”
Statistical properties of turbulence: an overview.: Good source of references.
Physicists Make Progress On The Bumpy Ride To Understanding Turbulence: New experiments examining vortex merging in 2D turbulent flows.
Competition of intrinsic and topographically imposed patterns in Bénard–Marangoni convection: An experiment.
Highly automated application process for innovative painting system: Lufthansa is working on an aircraft surface inspired by shark skin, containing micro-ridges.
A Kind of Boundary-Layer ‘Flutter’ : The Turbulent History of a Fluid Mechanical Instability: History of early turbulence and fluid stability research.
2D Vortex Dynamics: Evolution of a vortex system in two dimensions. An interactive webpage using Julia.
The Ancient Persian way to keep cool: using “windcatchers”.
Swalbe.jl: A lattice Boltzmann solver for thin film hydrodynamics: A Julia program.
Paradoxical ratcheting in cornstarch: A fluid with shear thickening climbs up a vibrating plate against gravity.
Return to Dead Mountain: This story about the mysterious deaths of campers 55 years ago in northern Russia is really a story about fluid dynamics, starring the Kármán vortex street.
Forecasting the weather with neural ODEs: Using Julia to forecast the weather with machine learning techniques.
Why flying insects gather at artificial light: Finally, a convincing explanation for a commonly observed phenomenon.
Famous Experiment Dooms Alternative to Quantum Weirdness: The Copenhagen interpretation is still our most parsimonious model of the microworld.
Stripe-hexagon competition in forced pattern-forming systems with broken up-down symmetry: Copy at https://arxiv.org/pdf/nlin/0410061.pdf
Theoretical Hydrodynamics: A classic and quite clear and useful text.
Turbulence, The Oldest Unsolved Problem in Physics: My article in Ars Technica.
Origin and dynamics of vortex rings in drop splashing: Experiment with very high quality visualizations, and development of some theory and modeling.
On the Navier-Stokes “Millenium Prize”: The problem; translation of the proposed solution.
waterlily.jl: “A differentiable and backend-agnostic Julia solver to simulate incompressible viscous flow and dynamic bodies”.
The Scientific Problem That Must Be Experienced: Very interesting study of the interplay between science and art in grasping turbulence.
Depletion of nonlinearity in two-dimensional turbulence: Theory and simulation.
Illuminating siphoning demonstration: Short video that illustrates the role of pressure in liquid siphoning.
FYFD—Celebrating the physics of all that flows: A website devoted to fluid dynamics.
Preferred pattern of convection in a porous layer with a spatially non-uniform boundary temperature: “The problem of finite-amplitude thermal convection in a porous layer between two horizontal walls with different mean temperatures is considered when spatially non-uniform temperature with amplitude L* is prescribed at the lower wall. The nonlinear problem of three-dimensional convection for values of the Rayleigh number close to the classical critical value is solved by using a perturbation technique.”
Mathematicians Find Wrinkle in Famed Fluid Equations: Determinism and the NS equations.
Politics
Luddites and “Planet of the Humans”: Detailed criticism of Michael Moore’s execrable documentary about renewable energy.
My dream died, and now I’m here: Sabine Hossenfelder’s fascinating account of her journey from academia to YouTube.
Astronomy
Lightest Exoplanet Imaged So Far?: “A team of astronomers using ESO’s Very Large Telescope has imaged a faint object moving near a bright star. With an estimated mass of four to five times that of Jupiter, it would be the least massive planet to be directly observed outside the Solar System. The discovery is an important contribution to our understanding of the formation and evolution of planetary systems.”
Saturn’s Mysterious Hexagon Shows its True Colors: Stunning image from NASA’s Cassini orbiter.
Infrared Star Trails Over Texas: A simple idea, but an impressive effect.
How to get a photograph of the five planets: The trick is to know where to look, and when.
Forgotten Faces of Science: The Women Who Classified The Stars: In comic-book form.
Why Charon has a red cap: Pluto and its moon share a bit of atmosphere.
Annie Jump Cannon’s Birthday: An extraordinary American astronomer.
The sky will literally be the limit at new Mayland planetarium this spring: “Construction is underway on a new planetarium located at the Mayland Community College’s Bare Earth to Sky Park in Yancey County and will open to the public spring of 2021.” The location has international dark sky certification.
The Moon’s Changing Shape Seen From Orbit for the First Time: The tidal forces caused by the Earth’s gravity have a subtle effect on the shape of the Moon. This has now been measured by two NASA missions orbiting our natural satellite.
Astronaut’s Brother Recalls A Man Who Dreamed Big: The fascinating story of Ronald McNair, one of the astronauts killed in Challenger explosion.
PlanetOrbits.jl: Tools for solving and displaying Keplerian orbits for exoplanets.: “The primary use case is mapping Keplerian orbital elements into Cartesian coordinates at different times. A Plots.jl recipe is included for easily plotting orbits.”
Lagrange Points: A very nice interactive page that teaches you about several topics in orbital dynamics.
Astronaut Ice Cream Is a Lie: Sorry.
The Control and Use of Libration-Point Satellites: Orbits and stationkeeping around Lagrange points.
First Ever Comet Material Found on Earth: 28 million years ago a comet exploded over Egypt, leaving behind molten glass and microscopic diamonds.
There Was No Big Bang Singularity: Descriptions of the Universe’s origins as a singularity, although common even on the part of cosmologists, are out of date.
Orbital Insertion Burn a Success, Webb Arrives at L2: “Today, at 2 p.m. EST, Webb fired its onboard thrusters for nearly five minutes (297 seconds) to complete the final postlaunch course correction to Webb’s trajectory. This mid-course correction burn inserted Webb toward its final orbit around the second Sun-Earth Lagrange point, or L2, nearly 1 million miles away from the Earth.”
Postal Service Honors NASA Planetary Science: These 2016 stamps are gorgeous.
Solar Wind Triggers Lightning on Earth: The connection between space weather and actual weather just got stronger.
The Most Amazing Map You’ll See Today: Brent Tully has mapped the universe out to a distance of 100 million light years.
LIGO mirrors have been cooled to near their quantum ground state: “LIGO is designed to detect gravitational waves, but it is also proving to be a fantastic laboratory for pushing the limits of quantum physics.”
The Reason for the Darkness of the Night: A biography of Edgar Allan Poe which focusses on his engagement with science in America.
CCC and the Fermi paradox: Did ancient civilizations send information to us through the Big Bang?
Alien star system buzzed the Sun: 70,000 years ago a dwarf star passed through the Oort cloud.
ISU Planetarium Has a Birthday: Illinois State University’s Planetarium just turned 50.
Astrophysicists Tackle the Sun and One of Physics’ Biggest Unsolved Problems: Progress on the coronal heating problem.
RS Puppis Puts on a Spectacular Light Show: A stunning Hubble image, and a time-lapse movie, showing the “light echo” from a variable star.
Oppenheimer’s forgotten astrophysics research explains why black holes exist: Apparently there’s a popular movie out now that’s supposed to be about Oppenheimer, but doesn’t mention his only significant scientific work.
NASA’s Webb Takes Its First-Ever Direct Image of Distant World: The James Webb Space TelescopejwstArticle? has captured direct infrared images of exoplanet HIP 65426 b, first discovered by the VLTvltChile?.
Talking with the ISS using LASERs: “The entire transmission on June 5th lasted 148 seconds and achieved a maximum data rate of 50 megabits per second […] 3.5 seconds to transmit a single copy of the [HD] video message, which would have taken more than 10 minutes using traditional downlink methods.”
Scale Comparisons of the Solar System’s Major Moons: … in the form of a lovely presentation slide.
Cornell postdoc detects possible exoplanet radio emission: “By monitoring the cosmos with a radio telescope array, an international team of scientists has detected radio bursts emanating from the constellation Boötes – that could be the first radio emission collected from a planet beyond our solar system.”
Mystery in the Perseus Cluster: ‘“I couldn’t believe my eyes,” says Esra Bulbul of the Harvard Center for Astrophysics. “What we found, at first glance, could not be explained by known physics.”’
JWST Data Collection: Webb Telescope instruments, data collection, and links to documentation.
Jupiter and Saturn’s Great Conjunction Is the Best in 800 Years—Here’s How to See It: “The giant planets will appear spectacularly close together in Earth’s sky during the solstice on December 21”.
“If you seek his memorial, look about you”: My note on Christopher Wren’s 383rd Birthday.
One Mars Moon Eclipsing Another: A very cool movie constructed from Curiosity frames.
Linux for Astronomers: Distro Astro: “This distribution bundles together astronomy software to help users with tasks like running observatories or planetariums, doing professional research or outreach.”
Rare Exoplanet Found in Cluster: “Three new exoplanets have been discovered inside a star cluster, which is a rare find as only a handful of such exoplanets are known to exist. However, one of the three new finds is even more remarkable — it orbits a star that appears to be ‘an almost perfect solar twin.’”
Kepler Finds Large Planet: NASA’s partially disabled Kepler spacecraft has discovered a large, Neptune-like planet 180 lightyears away.
Flying Cross Country in a New Horizons Space Probe: Clever visualization.
Solar P-P Neutrinos Detected: Their long-sought detection provides strong evidence that most of the Sun’s energy output is the result of proton-proton fusion.
A Solar Windsock: Using a comet’s tail to measure the turbulence in the solar wind.
Is It a Planet? Astronomers Spy Promising Potential World around Alpha Centauri: “The candidate could be a ‘warm Neptune’ or a mirage. Either way, it signals the dawn of a revolution in astronomy”.
Friends of Arlington’s Planetarium: The home page of the Arlington Planetarium.
Upgraded Planetarium at Union Station in Kansas City: The old train station is now used as a cultural center and includes a science center. Its Arvin Gottlieb planetarium has just received a major upgrade, including a new 4K projector.
The Sun’s Magnetic Field is about to Flip: “Something big is about [2013] to happen on the sun. According to measurements from NASA-supported observatories, the sun’s vast magnetic field is about to flip. ‘It looks like we’re no more than 3 to 4 months away from a complete field reversal,’ says solar physicist Todd Hoeksema of Stanford University. ‘This change will have ripple effects throughout the solar system.’
Rosetta scientists plan to eventually land the mothership: “That’s the right way to die.”
Moon Phase and Libration, 2018: Explanation and superb video of the appearance of the Moon from Earth during every moment of 2018, including tilt angle and libration.
Confirmed: Salvaged F-1 Engine is from Apollo 11 Rocket: The salvage feat was performed by Amazon founder Jeff Bezos’ company Bezos Expeditions.
Neurodome: These scientists are crowdsourcing funding to create planetarium shows about the brain.
NASA Television to Air Space Station Cargo Ship Launch, Docking: “NASA will provide live coverage on NASA Television […] of the launch and docking of a Russian cargo spacecraft to the International Space Station beginning at 11:15 p.m. EST Sunday, Feb. 14. […] Following a two-day journey, the spacecraft will automatically link up to the station’s Pirs docking compartment at 1:20 a.m. Wednesday, Feb. 17.”
Edgar Allan Poe’s Physical Cosmology: In Poe’s Eureka, he anticipated parts of modern cosmology, presenting, for example, the correct resolution of Olber’s paradox.
Parallel Supercomputing for Astronomy: “The Celeste research team spent three years developing and testing a new parallel computing method that was used to process the Sloan Digital Sky Survey dataset and produce the most accurate catalog of 188 million astronomical objects in just 14.6 minutes with state-of-the-art point and uncertainty estimates.”
ALMA Discovers Comet Factory: Observations performed by the new Atacama Large Millimeter/submillimeter Array (ALMA) have verified the existence of a theoretically proposed “dust trap,” a region near a star where comets may be formed.
First Images from the James Webb Space Telescope: Five wonderful images on NASA’s website.
Satellite Licensing: FCC Should Reexamine Its Environmental Review Process for Large Constellations of Satellites: The Starlink swarm, which has interfered with astronomical observations with impunity, may finally be subject to environmental review.
Meet the largest science project in US government history—the James Webb Telescope: My article introducing the infrared telescope that was to be launched in 2018.
Sun Sends More “Tsunami Waves” to Voyager 1: The probe is now confirmed to be in interstellar space (but has certainly not “left the solar system”).
The leap second: Because our clocks are more accurate than the Earth: The surprising physics of the planet’s rotation: my article in Ars Technica.
The Rings and Moons of Uranus: “captured almost exactly edge-on to Earth.”
New Kind of Variable Star Discovered: Due to extremely accurate observations by the European Southern Observatory
Astronomers find “missing matter”, solving decades-long mystery of outer space: This is big news, and some interesting observational astronomy.
Mars Opportunity Rover Sets Off-World Driving Record: The rover just [2014] passed the 25-mile mark. Visit the link for a map of its travels.
Rosetta fuels debate on origin of Earth’s oceans: Results cast doubt on the theory that Earth’s water came from comets.
As Earth spins faster, Meta joins fight against leap seconds: Facebook is whining about having to handle time correctly.
Shocked Astronomers Discover Strange New Type of Space Object: “It’s something that no astronomer has ever seen before, according to NASA: An asteroid with six comet-like tails that isn’t moving like a comet and it’s not made of ice. It’s just hanging up there, rotating like a crazy space spider.”
Elon Musk’s Starlink satellites hindering detection of near-Earth asteroids: “A new study has concluded that the sheer amount of Elon Musk’s Starlink satellites in orbit is causing streaks to appear on telescope imagery, obstructing the observation of asteroids.”
Voices from the Sky: The Friends of Arlington’s PlanetariumarlingtonPlanetarium? are hosting a fun, online, music-based program about space science and history with Dr. Jim Thorne, Sunday, November 15th, 3pm EST.
NASA - Spot The Station: See the International Space Station
Atlanta Students Bring Mars to Earth: “As part of a group called Aspiration Creation, students from the Dunwoody/Sandy Springs area participated in a project with the European Space Agency (European equivalent to NASA) to take real live images of Mars.”
Risk of asteroid hitting Earth higher than thought, study shows: “A global network that listens for nuclear weapons detonations detected 26 asteroids that exploded in Earth’s atmosphere from 2000 to 2013, data collected by the Comprehensive Nuclear Test Ban Treaty Organization shows.” This data raises the impact probability above some previous estimates.
Chandra :: Photo Album :: RX J1131-1231 :: March 5, 2014: Fantastic example of gravitational lensing.
Every NASA Authorization: A list of every NASA authorization passed by the U.S. Congress, with links to the texts of the bills.
Ten New Moons Discovered Around Jupiter: ‘The newly plotted moons of Jupiter include one “oddball” that orbits in the wrong direction and may be the remnant of a head-on collision.’
The Space Station Accelerates: To maintain orbit, the ISS must fire its rockets now and then. This movie demonstrates the departure from weightlessness experienced inside the station.
Accident delays launch of James Webb Space Telescope: A minor mishap during launch preparations has pushed back the planned launch date of the James Webb Space TelescopejwstArticle? to at least December 22.
Unintended electromagnetic radiation from Starlink satellites detected with LOFAR between 110 and 188 MHz: The Starlink constellation of internet satellites emit radio signals far outside their assigned frequency band, creating interference with radio astronomy.
Enduring Mystery of Moon’s Toxic Dust Solved from Apollo Findings: Measurements of dust accumulation on instruments left in place during the first Moon landings reveal a rate of buildup of 1mm/1000 years, faster than geologic predictions.
Space Germs: Interesting history of the efforts to avoid both infecting, and becoming infected by, microbial life on other worlds.
Planetariums — not just for kids: “Planetariums are not just for education, or even astronomy: they could display all sorts of data, if only scientists thought to use them”.
IERS Bulletins: Keep track of the Earth’s rotation with the help of the International Earth Rotation Service.
New Galaxy Most Distant Yet Discovered: Found by the Hubble, we observe it as it was 700 million years after the Big Bang, producing stars at a rapid pace. It’s called z8_GND_5296.
Staff Recommends Denying Historic Designation for Potential High School Site: “Under the plan for historic designation, the Education Center and the adjacent David M. Brown Planetarium would be saved from possible demolition […] School Board members do not support pursuing historic designation”.
Freefall achieved on LISA Pathfinder: An amazing project for the space-based observation of gravitational waves.
Amesbury Rock Came From Soviet Spacecraft: “Phil Green knew he’d found something unusual when he pulled the strange green rock out of the Merrimack River six years ago, but it wasn’t until recently that he found out his discovery was truly out of this world.”
Arecibo telescope faces a catastrophic collapse, must be deconstructed: A sad day for radio astronomy and for science.
Is Energy Conserved When Photons Redshift In Our Expanding Universe?: By Ethan Siegel.
Studying the Solar System with NASA’s Webb Telescope: A 2016 special issue of the Publications of the Astronomical Society of the Pacific is devoted to science that will be made possible by the telescope.
Life’s First Handshake: Chiral Molecule Detected in Interstellar Space
How Many Planets are in the Solar System?: And why Pluto is not one of them.
Feeding Galaxy Caught in Distant Searchlight: “Astronomers using ESO’s Very Large Telescope have spotted a distant galaxy hungrily snacking on nearby gas.[…]This is the best direct observational evidence so far supporting the theory that galaxies pull in and devour nearby material in order to grow and form stars.”
The Surface of Mercury: NASA spacecraft have assembled a complete map of the surface of the mysterious planet, which is displayed in this stunning movie.
Comet ISON: 12 cool facts.: Much better than the run of the mill ISON article.
A new non-parametric method to infer galaxy cluster masses from weak lensing: “a new, non-parametric method to infer deprojected 3D mass profiles M(r) of galaxy clusters from weak gravitational lensing observations…We provide an efficient implementation in Julia code that runs in a few milliseconds per galaxy cluster.”
NASA’s Asteroid Mission Packs Away Its Cargo. Next Stop: Earth: “The OSIRIS-REX mission has been investigating a carbon-rich asteroid named Bennu for the last couple of years.”
Black Hole Scientists Win Nobel Prize in Physics: “The story of the discovery of black holes demonstrates vividly how powerful pure mathematics can be in the quest to understand nature.”
USGS Releases First-Ever Comprehensive Geologic Map of the Moon: 
“Have you ever wondered what kind of rocks make up those bright and dark splotches on the moon? Well, the USGS has just released a new authoritative map to help explain the 4.5-billion-year-old history of our nearest neighbor in space.”
“Have you ever wondered what kind of rocks make up those bright and dark splotches on the moon? Well, the USGS has just released a new authoritative map to help explain the 4.5-billion-year-old history of our nearest neighbor in space.”
We don’t know how the universe began, and we will never know: Excellent video (with transcript) about ascientific creation myths written in the language of mathematics.
Webb inspects the heart of the Phantom Galaxy: A combined image from the James Webb Space TelescopejwstArticle? and the Hubble: “New images of the spectacular Phantom Galaxy, M74, showcase the power of space observatories working together in multiple wavelengths.”
Nebulosity is now free and open-source: The capture and processing application for astronomy photography is now developed on Github. For Windows and macOS only.
The Parker Solar Probe Captures Surprising Images of Venus Nightside: ‘A visible glow from our sister planet’s nightside sheds new light on a 300-year-old observing enigma dubbed the “ashen light.”’
Comet dust found in Antarctica: “Researchers have discovered comet dust preserved in the ice and snow of Antarctica, the first time such particles have been found on Earth’s surface.”
Gorgeous Image of Saturn by Cassini: A mosaic of images taken by the Cassini spacecraft in the shadow of Saturn show the Earth and other planets in the background, as well as interesting ring and moon detail.
Five major planets to line up in rare planetary conjunction: “The last time this conjunction happened was 2004 and it won’t be seen again until 2040.”
Juno Data Indicates “Sprites” or “Elves” Frolic in Jupiter’s Atmosphere: 
New results from NASA’s Juno mission at Jupiter reveal for the first time these flashes (transient luminous events, or TLEs) on another planet. The findings were published on Oct. 27, 2020, in the Journal of Geophysical Research: Planets.
New results from NASA’s Juno mission at Jupiter reveal for the first time these flashes (transient luminous events, or TLEs) on another planet. The findings were published on Oct. 27, 2020, in the Journal of Geophysical Research: Planets.
Spacecraft may have captured interstellar dust particles: The Stardust spacecraft has probably collected seven dust particles from beyond the solar system.
Is the Solar System Stable?: A good summary of recent computational results.
Star’s black hole encounter puts Einstein’s theory of gravity to the test: An impressive confirmation of the General Theory of Relativity.
Rosetta’s comet ‘sweats’ two glasses of water a second: ESA’s Rosetta spacecraft detects enough water vapor coming off of comet 67P/Churyumov–Gerasimenko to fill an Olympic swimming pool in 100 days. “Glasses” and “swimming pools” are the only units of volume offered by the article on the European Space Agency website, which is otherwise quite good.
Jocelyn Bell, woman of steel: “Three Nobel Prizes have now been awarded for pulsars, but none has gone to the woman who discovered them.”
Maria Mitchell’s 195th Birthday: My notice on the Arlington Planetarium website.
Newly discovered green comet comes close to Earth: You might be able to see it, near Polaris, through binoculars, after moonset on Thursday (2FEB) morning, in a dark locale.
The Partial Solar Eclipse of October 23, 2014: Enjoy my brief note on the Arlington Planetarium website.
Ask Ethan: Are we expanding along with the Universe?: Exceptionally clear explanation of the nature of the expansion of the universe, with enriching figures and artifacts.
Total lunar eclipse May 15-16, 2022: In a few days most of the Western hemisphere will be treated to a total supermoon eclipse.
Experiment with Planetary Systems: A game that challenges you to create a system that can last for 500 years.
TIC 168789840: A Sextuply-Eclipsing Sextuple Star System: “We report the discovery of a sextuply-eclipsing sextuple star system from TESS data, TIC 168789840, also known as TYC 7037-89-1, the first known sextuple system consisting of three eclipsing binaries.”
You can see the Milky Way Galaxy from Earth with the naked eye: A lovely site dedicated to views of our galaxy from Earth.
SKY GUY VIEWING ALERT!!!! COMET NEOWISE: Greg Redfern explains how to see and photograph the comet. There aren’t many like this in a lifetime, so take advantage of the opportunity.
Edgar Allan Poe’s engagement with American science: A review of this biographytresch21? of Poe by James Dinneen. Mentions that Poe correctly described the solution to Olber’s paradox, but, sadly, Dinneen does not understand the solution, and garbles it.
ESO Telescope Sees Star Dance Around Supermassive Black Hole, Proves Einstein Right: The “dance” is the precession in the orbit, like the precession of Mercury’s orbit that was an early confirmation of Einstein’s theory of gravitation.
Scientists Discover how Soil is Formed on Small Asteroids: The mechanism is not the same as the common model for the formation of soil on the moon.
Mars on Earth: The ESA has a model of Mars that is “used to put prototype planetary rovers through their paces. Officially known as the Automation & Planetary Robotics Lab, its nickname is the ‘Mars Yard’.” Follow the link for a picture of the Mars Yard in use.
NASA’s Juno Mission Expands Into the Future: “The spacecraft, which has been gathering data on the gas giant since July 2016, will become an explorer of the full Jovian system – Jupiter and its rings and moons.” Juno “will now continue its investigation of the solar system’s largest planet through September 2025, or until the spacecraft’s end of life.”
Identification of carbon dioxide in an exoplanet atmosphere: The James Webb Space TelescopejwstArticle? has detected CO2 in the atmosphere of a gas giant exoplanet known as WASP-39b using transmission spectroscopy. This planet has about the same mass as Saturn but is about 50% larger.
Meteorite Phosphorus Aided Life on Early Earth: “New research shows that a key element for life on Earth was delivered to our planet on meteorites.”
The Giant Spider of Mercury: Beautiful, detailed images of the planet closest to the Sun, courtesy of the MESSENGER spacecraft.
Arecibo radio telescope’s massive instrument platform has collapsed: In a blow to the international radio astronomy community, to Puerto Rico, and to the standing of U.S. Science, the iconic Arecibo observatory is gone.
NASA Unveils New Searchable Video, Audio and Imagery Library for the Public: “NASA Image and Video Library allows users to search, discover and download a treasure trove of more than 140,000 NASA images, videos and audio files from across the agency’s many missions in aeronautics, astrophysics, Earth science, human spaceflight, and more. Users now can embed content in their own sites and choose from multiple resolutions to download.”
Nasa Successfully Tests 3D-Printed Rocket Component: “Additive printing could lead to cheaper and quicker production of rockets”.
How NASA Designed a Helicopter That Could Fly Autonomously on Mars: “This the first time we’ll be flying Linux on Mars. […] The software framework that we’re using is one that we developed at JPL for cubesats and instruments, and we open-sourced it a few years ago. So, you can get the software framework that’s flying on the Mars helicopter, and use it on your own project.”
Gravitation
On the Hypotheses Which Lie at the Bases of Geometry: The famous paper, posthumously published, wherein Reimann introduces curved space and speculates on its application to the real world. This version translated by W. K. Clifford.
LIGO:
Noether’s first theorem and the energy-momentum tensor ambiguity problem: From the abstract: ‘Noether’s theorems are widely praised as some of the most beautiful and useful results in physics. However, if one reads the majority of standard texts and literature on the application of Noether’s first theorem to field theory, one immediately finds that the “canonical Noether energy-momentum tensor” derived from the 4-parameter translation of the Poincaré group does not correspond to what’s widely accepted as the “physical” energy-momentum tensor for central theories such as electrodynamics.’
Arch and scaffold: How Einstein found his field equations: “In his later years, Einstein often claimed that he had obtained the field equations of general relativity by choosing the mathematically most natural candidate. His writings during the period in which he developed general relativity tell a different story.”
Einstein’s Spacetime: Good tutorial.
Belated Decision in the Hilbert-Einstein Priority Dispute: Hilbert did not beat Einstein to the Theory of General Relativity.
Hamilton’s Principle and the General Theory of Relativity: Translated into English at https://einsteinpapers.press.princeton.edu/vol6-trans/252.
A Century Ago, Einstein’s Theory of Relativity Changed Everything: A breezy summary of the development of the theory and its impact.
General relativity: 100 years of the most beautiful theory ever created: My article contains an overview of the theory, its authorship, and its experimental verifications.
The Renewal of Einstein’s Theory of Relativity in the Post-War Era: After a period of intense interest following the eclipse expeditions, there was a deep lull in general concern with GR, followed by a revivial in the 1950s.
The Wormhole Publicity Stunt: “The best way to understand the ‘physicists create wormholes in the lab’ nonsense of the past few days is as a publicity stunt”.
How Einstein reinvented reality: Einstein and Hilbert race to produce the equations of General Relativity. Part of the Scientific American special issue: “100 Years of General Relativity”.
Which falls faster—a feather or a hammer?: The equivalence of inertial and gravitational mass demonstrated on the Moon.
On the foundations of generalised relativity: An English translation of Einstein’s review article submitted March 1916.
An Interview With Dr. Lee Phillips Part Five: Emmy Noether Serving As Einstein’s Tutor: We talk mostly about Emmy Noether’s contribution to General Relativity.
Noether’s Theorem and Arthur Eddington: The survival of the former in physics culture owes a debt to the latter.
An eerie quantum effect of magnetic fields also applies to gravity: The gravitaional Aharonov-Bohm effect.
Of pots and holes: Einstein’s bumpy road to general relativity: Einstein’s early GR publications; his discovery of a special case of Noether’s Theorem several years before Noether discovered the general theorem.
Scientists use the Tokyo Skytree to test Einstein’s theory of general relativity: … by measuring the difference in the rate that time passes at the top and base of the tower.
Empty out the drawer: Following Einstein’s path to General Relativity: Brief, engaging history of the development of GR. Mentions that Einstein called the drawer at the patent office where he stashed his physics work “his ‘Department of Theoretical Physics.’ Einstein’s Department had more revolutionary ideas than most actual departments.”
Putting Relativity to the Test: A useful popular brief summary of the major experimental confirmations of GR.
Einstein Versus the Physical Review: The story of Einstein’s surprise that his article about gravitational waves was sent to a reviewer, and his withdrawal of his manuscript.
Here’s the first person to spot those gravitational waves: Marco Drago saw the first gravitational wave on 14 September 2015.
Observation of Gravitational Waves from a Binary Black Hole Merger: A historic day for science.
Energy is Conserved in General Relativity: Undated manuscript claiming, with detailed examples, that the various claims of energy non-conservation in GR are fallacies. I believe the author is mistaken.
Energy Is Not Conserved: Popular and clear note on conservation of energy in general relativity.
More physics
Weak interactions with lepton-hadron symmetry: “We propose a model of weak interactions in which the currents are constructed out of four basic quark fields and interact with a charged massive vector boson. We show, to all orders in perturbation theory, that the leading divergences do not violate any strong-interaction symmetry and the next to the leading divergences respect all observed weak-interaction selection rules. The model features a remarkable symmetry between leptons and quarks. The extension of our model to a complete Yang-Mills theory is discussed.”
2021_FortranCon Benchmarks: Comparison of of code and performance between Julia and Fortran on a 2D particle simulation.
On Nuclear Forces: “The various types of exchange forces that are being used in current discussions of nuclear structure may all be simply expressed in terms of a formalism which attributes five coordinates to each heavy particle and applies the Pauli exclusion principle to all the particles in the system. The simplest assumption for the interaction law is that which implies equality of proton-proton and neutron-neutron forces and also equality with the proton-neutron forces of corresponding symmetry. This is in accord with the empirical knowledge of these interactions at present.”
Closed-form solutions to nonlinear PDEs: Surprisingly many nonlinear partial differential equations of real interest have closed-form solutions.
‘Shut up and calculate’: how Einstein lost the battle to explain quantum reality: Interesting essay on the history of orthodoxy in quantum mechanics.
Partial-symmetries of weak interactions: Said to be the paper that kicked off the Standard Model.
Broken Symmetries: “Some proofs are presented of Goldstone’s conjecture, that if there is continuous symmetry transformation under which the Lagrangian is invariant, then either the vacuum state is also invariant under the transformation, or there must exist spinless particles of zero mass.”
Quantum theory cannot consistently describe the use of itself: “Quantum theory provides an extremely accurate description of fundamental processes in physics. It thus seems likely that the theory is applicable beyond the, mostly microscopic, domain in which it has been tested experimentally. Here we propose a Gedankenexperiment to investigate the question whether quantum theory can, in principle, have universal validity. The idea is that, if the answer was yes, it must be possible to employ quantum theory to model complex systems that include agents who are themselves using quantum theory. Analysing the experiment under this presumption, we find that one agent, upon observing a particular measurement outcome, must conclude that another agent has predicted the opposite outcome with certainty. The agents’ conclusions, although all derived within quantum theory, are thus inconsistent. This indicates that quantum theory cannot be extrapolated to complex systems, at least not in a straightforward manner.” (Arxiv preprint appeared 2016.)
It’s hard to think when someone Hadamards your brain: Critique of “Quantum theory cannot consistently describe the use of itself”FrauchigerRenner2016?.
The Elegant Universe: 25th Anniversary Edition: Mathematician Peter Woit looks at the string theory hype machine on the 25th anniversary of Brian Greene’s The Elegant Universe.
JuliaHEP: High energy physics packages. Includes compatibility layers and partial replacements for ROOT.
Getting to the Bottom of Noether’s Theorem: An algebraic approach.
Accuracy of tropical peat and non-peat fire forecasts enhanced by simulating hydrology: Fire forecasting using Flux.jl.
C. Brenhin Keller: An assistant Professor of Earth Sciences at Dartmouth using Julia in research and teaching. Many links to Julia Earth science resources.
What’s Going Right in Particle Physics: Peter Woit: “While there are a lot of ways in which I disagree with Hossenfelder’s critique, there are some ways in which it is perfectly accurate.” He never mentions what are the ways in which he disagrees, but has interesting things to say, as usual.
Wormhole Publicity Stunts: Past, Present and Future: Looks like this nonsense isn’t going away any time soon.
How Quantum Mechanics can consistently describe the use of itself: “We discuss the no-go theorem of Frauchiger and Renner based on an ‘extended Wigner’s friend’ thought experiment which is supposed to show that any single-world interpretation of quantum mechanics leads to inconsistent predictions if it is applicable on all scales. We show that no such inconsistency occurs if one considers a complete description of the physical situation.”
The Mystery of Spin: More nonsense from Scientific American, this time about spin in quantum mechanics.
Julia as a unifying end-to-end workflow language on the Frontier exascale system: “Julia emerges as a compelling high-performance and high-productivity workflow composition language, as measured on the fastest supercomputer in the world.”
What are the fastest routes to fusion energy?: The authors conclude that no approach using deuterium fuel (which includes most laser fusion devices such as the NIF) is on a fast path toward fusion energy. They show that the most likely candidates employ high density plasmas.
Why the ‘Mother of the Atomic Bomb’ Never Won a Nobel Prize: This article about Lise Meitner is interesting because of information from newly translated correspondence. As my book about Emmy Noether nears completion I am struck by the parallels with the life of Meitner: both robbed of credit and opportunities because of their sex, and both Jews endangered by the rise of the Nazis. Both women spent time in Bryn Mawr College, as well.
The Standard Model: A detailed history of discoveries leading to the Standard Model of particle physics.
What is Entropy?: A little book by John Baez. This looks good.
Hamilton’s principle and the conservation theorems of mathematical physics: This article may be responsible to reintroducing Noether’s Theorem to the physics world, although it presents a highly simplified version.
Increasing freshwater supply to sustainably address global water security at scale: “We show that the atmosphere above the oceans proximal to the land can yield substantial freshwater, sufficient to support large population centers across the globe, using appropriately engineered structures.”
What’s going wrong in particle physics?: Physicist Sabine Hossenfelder explains the problem with contemporary particle physics in an engaging and illuminating video.
Publicity Stunt Fallout: The ongoing train wreck of the false hype around the “wormhole in a lab”. Scientific misconduct, shameless hype, and dishonesty from physicists have gotten worse since the cold fusion scandal, not, as we might have hoped, better.
Particle Theory Timeline: A useful timeline for the Standard Model (but, sadly, without links to papers).
Measurement of e⁺e¯ Momentum and Angular Distributions from Linearly Polarized Photon Collisions: Matter from light.
Antimatter Over Eurasia: Fascinating measurements and analysis of the spectrum of gamma radiation encountered during commercial airline travel.
VisualPDE: Interactive live solutions of PDE systems, right on your device
Exclusive: Laser-fusion facility heads back to the drawing board: The failure to replicate the alleged ignition of a fusion target one year ago suggests that the event was an accident, in the sense that we still don’t understand how to create the conditions leading to ignition in an indirect-drive laser experiment.
Exponential Economist Meets Finite Physicist: Thermodynamic limits to economic growth.
Why science relies too much on mathematics: Physicist Roland Ennos promotes his new book (which looks interesting) with an article in New Scientist about over-reliance on mathematics in physics. I don’t think he’s made his point convincingly, but the article contains several interesting historical tidbits.
The Feynman Lectures on Physics, Vol. II: LOADING PAGE…
Einstein’s Tutor: A review of my book in Science: “Phillips’s writing shines in his exhaustively researched historical narrative…Accessible to both nonscientists and trained physicists…ultimately, everyone will learn something new from this book.”
Mysteries of the gravitational 2-body problem: The Runge–Lenz vector, hidden symmetries in the Kepler problem, and so much more. A fantastic ride.
DynamicQuantities.jl: Type stable units in Julia: Along the lines of Unitful, but storing dimensions as values rather than as parametric types. This leads to greater efficiency in many circumstances.
Trixi.jl: “Trixi.jl is a numerical simulation framework for conservation laws written in Julia. A key objective for the framework is to be useful to both scientists and students. Therefore, next to having an extensible design with a fast implementation, Trixi.jl is focused on being easy to use for new or inexperienced users, including the installation and postprocessing procedures.”
nicf.net: High-quality tutorial articles about mathematics and physics.
Practical Julia: My introduction to the best language for scientific computing.
Potential of the Julia programming language for high energy physics computing: “In this paper the applicability of using the Julia language for HEP research is explored, covering the different aspects that are important for HEP code development: runtime performance, handling of large projects, interface with legacy code, distributed computing, training, and ease of programming. The study shows that the HEP community would benefit from a large scale adoption of this programming language.”
Applications of Noether conservation theorem to Hamiltonian systems: “The Noether theorem connecting symmetries and conservation laws can be applied directly in a Hamiltonian framework without using any intermediate Lagrangian formulation. This requires a careful discussion about the invariance of the boundary conditions under a canonical transformation and this paper proposes to address this issue. Then, the unified treatment of Hamiltonian systems offered by Noether’s approach is illustrated on several examples, including classical field theory and quantum dynamics.”
A short review on Noether’s theorems, gauge symmetries and boundary terms: This widely-cited paper came out in 2016 but I just found out about it (too late to mention it in the book): “This review is dedicated to some modern applications of the remarkable paper written in 1918 by E. Noether. [I]n a single paper, Noether discovered the crucial relation between symmetries and conserved charges as well as the impact of gauge symmetries on the equations of motion. Almost a century has gone since the publication of this work and its applications have permeated modern physics. Our focus will be on some examples that have appeared recently in the literature. This review is aim[ed] at students, not researchers.” Also at https://arxiv.org/abs/1601.03616.
The Lazy Universe: An Introduction to the Principle of Least Action: Inspired by Lanczos’ classic text.
The Plucked String: Simulates the effect of pluck position on the timbre of plucked string instruments. An interactive webpage using Julia.
Fusion “Breakthrough” Won’t Lead to Practical Fusion Energy: A more sober assessment of the recent breathless hype from LLNL.
Latest on the Wormholes: “I had thought that the wormhole story had reached peak absurdity back in December, but last night some commenters pointed to a new development: the technical calculation used in the publicity stunt was nonsense, not giving what was claimed.” Yet Fermilab pushes on with the hype.
Can the compiler make the difference?: The gfortran, Cray, and Intel Fortran compilers have the same performance if the code is written using certain optimizations.
Symmetry and the Standard Model: From the publisher: “the first volume of a series intended to teach math in a way that is catered to physicists. Following a brief review of classical physics at the undergraduate level and a preview of particle physics from an experimentalist’s perspective, the text systematically lays the mathematical groundwork for an algebraic understanding of the Standard Model of Particle Physics.”
Fermions.jl: New Julia physics library: “Fermions.jl is a toolkit for designing and analysing second-quantised many-particle Hamiltonians of electrons, potentially interacting with each other.”
Dynamics of the Standard Model: Open access.
BOOK REVIEW on A New Kind of Science: Good reasons not to bother with Stephen Wolfram’s output.
Comparing the Performance of Julia on CPUs versus GPUs and Julia-MPI versus Fortran-MPI: a case study with MPAS-Ocean (Version 7.1): “In the end, we were impressed by our experience with Julia. It did fulfill the promise of fast and convenient prototyping, with the ability to eventually run at high speeds on multiple high-performance architectures – after some effort and lessons learned by the developers.”
Systems design 2: What we hope we know: Apenwar on engineering, science, magic, and much more. Long, rambling, and quite interesting.
Not Quite What Happened: Peter Woit continues his coverage of Quanta magazine’s amazing credulity around the ridiculous “wormhole” hype.
Happy Birthday to Emmy Noether: Happy 141st birthday to Emmy Noether. Look for my book about how she changed the course of physics, coming from PublicAffairs later this year.
Kid tries to make breeder reactor
Heavens-Above: This page helps you to track artificial sattelites.
