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kottke.org posts about physics

Cars vs Giant Bulge and Other Outlandish Vehicular Simulations

posted by Jason Kottke   May 06, 2022

It is Friday and this is the perfect Friday sort of post. BeamNG is a video game of sorts that’s “a dynamic soft-body physics vehicle simulator capable of doing just about anything”. In the simulator, you can quickly devise all sorts of situations with a variety of cars and then press play to see what happens, with (mostly) realistic physics and collisions. For instance, here’s Cars vs Big Bulge:

Chained Cars vs Bollards:

Cars vs 100 Fallen Trees:

Trains vs Giant Pit:

And many many more. My god if this simulator had been around when I was 12 years old, I might not have done anything else. Hell, if I downloaded and installed this right now, I might not ever get anything done ever again. (via @tvaziri)

What If the Moon Crashes Into the Earth?

posted by Jason Kottke   Feb 08, 2022

No doubt motivated by this month’s release of Moonfall, the latest movie from disaster shlockmeister Roland Emmerich, Kurzgesagt has made a video that shows what would happen to civilization should the Moon somehow get knocked from its orbit and head straight for the Earth. Spoiler: the Moon doesn’t even need to reach us to kill almost all life on the planet.

See also A Scientific Simulation of Seveneves’ Moon Disaster.

How the James Webb Space Telescope Orbits Nothing

posted by Jason Kottke   Feb 07, 2022

The James Webb Space Telescope is designed to be positioned near one of the five Lagrange Points in the Sun/Earth system, special areas of gravitational equilibrium that keep objects stationary relative to both the Earth and the Sun. Here’s how Lagrange Points work and why they are so useful for spacecraft like the Webb.

See also What Makes Lagrange Points Special Locations In Space.

How Does The James Webb Space Telescope Work?

posted by Jason Kottke   Jan 19, 2022

The James Webb Space Telescope is still winging its way to its permanent home at the L2 point1 about 930,000 miles from Earth — it’s due to arrive in about 4 days. It’s a massive and fascinating project and for his YouTube series Smarter Every Day, Destin Sandlin talked to Nobel laureate John Mather, the senior project scientist for the JWST, about how the telescope works.

Also worth a watch is Real Engineering’s The Insane Engineering of James Webb Telescope:

It really is a marvel of modern science & engineering — I can’t wait to see what the telescope sees once it’s fully operational.

  1. You can read about Lagrange points here or here…they are interesting!

Randomly Bouncing Balls Arrange Themselves Into Satisfying Patterns

posted by Jason Kottke   Jan 12, 2022

In this clever simulation, bouncing balls obeying the laws of physics somehow arrange themselves, mid-chaos, into neat patterns. This is immensely satisfying.

Spoiler: the trick here is a pair of simulations stitched together, like a physics Texas Switch: “Each sequence is obtained by joining two simulations, both starting from the time in which the balls are arranged regularly. One simulates forward in time, one backwards.”

Powers of Ten, Updated With Current Science

posted by Jason Kottke   Jan 05, 2022

Charles and Ray Eames’ 1977 short film Powers of Ten is one of the best bits of science communication ever created…and a personal favorite of mine. Here’s a description of the original film:

Powers of Ten takes us on an adventure in magnitudes. Starting at a picnic by the lakeside in Chicago, this famous film transports us to the outer edges of the universe. Every ten seconds we view the starting point from ten times farther out until our own galaxy is visible only a s a speck of light among many others. Returning to Earth with breathtaking speed, we move inward — into the hand of the sleeping picnicker — with ten times more magnification every ten seconds. Our journey ends inside a proton of a carbon atom within a DNA molecule in a white blood cell.

As an homage, the BBC and particle physicist Brian Cox have created an updated version that reflects what we’ve learned about the universe in the 45 years since Powers of Ten was made. The new video zooms out to the limits of our current observational powers, to about 100 billion light years away, 1000X wider than in the original. (I wish they would have done the zoom in part of the video too, but maybe next year!)

And if you’d like to explore the scales of the universe for yourself, check out the Universe in a Nutshell app from Tim Urban and Kurzgesagt — you can zoom in and out as far as you want and interact with and learn about objects along the way.

Most People Don’t Know How Bikes Work

posted by Jason Kottke   Nov 30, 2021

How do you steer a bike? You turn the handlebars to the left to go left, correct? Actually, you don’t: you turn the handlebars to the right to go left…at least at first. And also? Bikes don’t even need riders to remain upright…they are designed to steer themselves.

If you’d like to play around with your own bicycle geometries, try this web app for analyzing bicycle dynamics.

How Bowling Balls Are Made

posted by Jason Kottke   Nov 16, 2021

I have been a fan of how things are made videos since my Mister Rogers and Sesame Street days, so I was not expecting to be so surprised watching the video above about how bowling balls are made. It’s a ball — how complicated could it be? Well, it turns out that modern bowling balls contain an asymmetric weight block in the middle that looks a little like a car’s starter. Weird, right?

As I started to wonder why it would be advantageous to include such a lopsided core in a ball you want to roll predictably down a lane, I noticed YouTube’s algorithm doing its job in recommending that I watch Veritasium’s recent video on How Hidden Technology Transformed Bowling, which totally explains the wonky weight block thing:

The weight blocks are wonky in a precise way. They’re designed to cause the ball to contact the lane over more of the surface of the ball, giving it more traction once it hits the unoiled part of the lane, which is desirable for expert bowlers looking for a wicked hook. So cool! (thx, mick)

Update: Brendan Koerner wrote a piece for Wired several months ago about Mo Pinel, who revolutionized bowling with the asymmetric cores described in the video above.

Pinel toured Faball’s factory and examined a freshly made core that the company used in its Hammer brand. It had a symmetrical and unexciting shape — the center looked like a lemon, and there were two convex caps of equal size on either side. In a moment that has now passed into ball-design legend, Pinel grabbed the core, which was still soft because the polyester had yet to cure, and sliced off the ends with a palette knife. Then he smooshed the caps back on into positions that were slightly askew, so that the contraption now looked like a Y-wing fighter from Star Wars.

The ball that contained this revamped core, the Hammer 3D Offset, would become Pinel’s signature achievement. “That ball sold like hotcakes for three years, where the average life span of a ball was about six months,” says Del Warren, a former ball designer who now works as a coach in Florida. “They literally couldn’t build enough of them.” In addition to flaring like few other balls on the market, the 3D Offset was idiot-proof: The core was designed in such a way that it would be hard for a pro shop to muck up its action by drilling a customer’s finger holes incorrectly, an innovation that made bowlers less nervous about plunking down $200 for a ball.

(via @danhwylie)

What Would Life on a Flat Earth Be Like?

posted by Jason Kottke   Oct 05, 2021

So let’s say, for the sake of argument and against all scientific evidence to the contrary, the Earth was flat instead of being an oblate spheroid. What would life on a flat Earth be like? Well for one thing, gravity would present some challenges. From a 2018 piece by Doug Main at the Columbia Climate School:

People who believe in a flat Earth assume that gravity would pull straight down, but there’s no evidence to suggest it would work that way. What we know about gravity suggests it would pull toward the center of the disk. That means it would only pull straight down at one point on the center of the disk. As you got increasingly far from the center, gravity would tug more and more horizontally. This would have some strange impacts, like sucking all the water toward the center of the world, and making trees and plants grow diagonally, since they develop in the opposite direction of gravity’s pull.

And even more than that, gravity would tend to pull a flat disc shape back into a spheroid, so absent an intense spinning force (for which there is zero evidence) or some other completely unknown effect, a flat Earth couldn’t even exist:

For Earth to take the shape of a flat disk in the first place, gravity — as we know it — must be having no effect. If it did, it would soon pull the planet back into a spheroid.

A flat Earth would also likely not have a magnetic field (or at least one that is scientifically possible), meaning no atmosphere:

Deep below ground, the solid core of the Earth generates the planet’s magnetic field. But in a flat planet, that would have to be replaced by something else. Perhaps a flat sheet of liquid metal. That, however, wouldn’t rotate in a way that creates a magnetic field. Without a magnetic field, charged particles from the sun would fry the planet. They could strip away the atmosphere, as they did after Mars lost its magnetic field, and the air and oceans would escape into space.

Oh and no tectonic plates, volcanos, mountains, etc. Or GPS. Or weather. Or satellites. Or different night skies in, say, South Africa and Denmark. Or the Sun behaving the way it does in respect to the Earth. Or air travel. Or plant and animal life as it exists presently. To suppose a flat Earth also supposes that physics doesn’t explain our observable universe the way in which it reliably and comprehensively does. The simplest, best evidence for a round Earth is that we’re here living on it in the manner in which we are living on it.

A million people can call the mountains a fiction, yet it need not trouble you as you stand atop them.

See also What If the Earth Suddenly Turned Flat?, Flat Earthers and the Double-Edged Sword of American Magical Thinking, and Flat Earthers Listening to Daft Punk.

The Simple Physics Trick That Helps Trains Stay on Their Tracks

posted by Jason Kottke   Oct 04, 2021

Train wheels do not sit completely flat on the tracks — they’re designed with a slight taper that increases the stability of the train and allows the train to go around curves without any of the wheels skidding. In this short video, Tadashi Tokieda explains how those conical wheels keep trains on track.

See also Richard Feynman’s explanation of this and this science project at Scientific American. (via the prepared)

Here’s Why You’ll Fail the Milk Crate Challenge

posted by Jason Kottke   Sep 10, 2021

Bored of dying from Covid-19, Americans have dreamed up a more entertaining way to mortally wound themselves: the milk crate challenge. Wired asked structural engineer Dr. Nehemiah Mabry (who explained the different types of bridges to us earlier in the year) to explain the physics behind the challenge and why you shouldn’t attempt it. (via @pomeranian99)

Size Comparison: The Largest Black Hole in the Universe

posted by Jason Kottke   Aug 04, 2021

Black holes are the largest single objects in the universe, many times larger than even the biggest stars, and have no upper limit to their size. But practically, how big is the biggest, heaviest black hole in the universe? (A: More massive than the entire Milky Way.)

The largest things in the universe are black holes. In contrast to things like planets or stars they have no physical size limit, and can literally grow endlessly. Although in reality specific things need to happen to create different kinds of black holes, from really tiny ones to the largest single things in the universe. So how do black holes grow and how large is the largest of them all?

Videos about space are where Kurzgesagt really shines. I’ve seen all their videos about black holes and related objects, and I always pick up something I never knew whenever a new one comes out. This time around, it was quasistars and the surprisingly small mass of supermassive black holes located at galactic centers compared to the galaxies themselves.

“If It Doesn’t Shine In Your Face, You Don’t See Anything”

posted by Jason Kottke   Jul 28, 2021

Jocelyn Bell Burnell as a graduate student

As I’ve written before, in the history of astronomy and astrophysics, women have made major discoveries and played a significant role in advancing our understanding of the universe but have often not gotten the recognition their male peers enjoy. In 1967, while she was working on her doctoral research with her advisor Antony Hewish, Jocelyn Bell Burnell (then Jocelyn Bell) discovered a new and unusual kind of object, the pulsar. In this short documentary, Bell Burnell shares her story — how she got interested in radio astronomy, the prejudice with which she was treated as the only woman in her university program, how she discovered the first pulsar and persisted (more than once) through Hewish’s assertions that the object was “interference”, and how she was passed over for the Nobel Prize for her discovery.

In 2018, Bell Burnell was awarded the Special Breakthrough Prize in Fundamental Physics “for fundamental contributions to the discovery of pulsars, and a lifetime of inspiring leadership in the scientific community”, joining past honorees like the LIGO team, Stephen Hawking, and the team that discovered the Higgs boson. She donated the entire $3 million prize to the Institute of Physics to help support “PhD physics students from under-represented groups” with their educations.

It’s not justice, but I will note that Bell Burnell’s Wikipedia page is longer and more substantial than Hewish’s, despite his Nobel.

Visualization of How Fast a Ball Drops on Various Solar System Bodies

posted by Jason Kottke   Jul 14, 2021

This is an animation of how quickly an object falls 1 km to the surfaces of solar system objects like the Earth, Sun, Ceres, Jupiter, the Moon, and Pluto. For instance, it takes 14.3 seconds to cover that distance on Earth and 13.8 seconds on Saturn.

It might be surprising to see large planets have a pull comparable to smaller ones at the surface, for example Uranus pulls the ball down slower than at Earth! Why? Because the low average density of Uranus puts the surface far away from the majority of the mass. Similarly, Mars is nearly twice the mass of Mercury, but you can see the surface gravity is actually the same… this indicates that Mercury is much denser than Mars.

(via @thekidshouldsee)

UFOs Are Not Aliens

posted by Jason Kottke   Jun 01, 2021

Due to recent government reports, declassified data, media interest in those data & reports, and a long-simmering interest by the public, UFOs are back in the public imagination. Adam Frank, an astrophysicist at the University of Rochester who is searching for signs of extraterrestrial life, says that there’s little chance that UFOs are aliens.

I understand that U.F.O. sightings, which date back at least to 1947, are synonymous in the popular imagination with evidence of extraterrestrials. But scientifically speaking, there is little to warrant that connection. There are excellent reasons to search for extraterrestrial life, but there are equally excellent reasons not to conclude that we have found evidence of it with U.F.O. sightings.

If UFOs are alien craft, we would never see them:

There are also common-sense objections. If we are being frequently visited by aliens, why don’t they just land on the White House lawn and announce themselves? There is a recurring narrative, perhaps best exemplified by the TV show “The X-Files,” that these creatures have some mysterious reason to remain hidden from us. But if the mission of these aliens calls for stealth, they seem surprisingly incompetent. You would think that creatures technologically capable of traversing the mind-boggling distances between the stars would also know how to turn off their high beams at night and to elude our primitive infrared cameras.

More people talking about a thing doesn’t make it credible. More people talking about potential evidence of a thing doesn’t make it credible. Evidence makes something credible.

Was the Microwave Invented to Thaw Out Frozen Hamsters?

posted by Jason Kottke   May 28, 2021

We all know that the microwave oven was invented by Raytheon’s Percy Spencer in 1945. What this video presupposes is, maybe it was invented to thaw out frozen hamsters? And somehow James Lovelock, who formulated the Gaia hypothesis, is involved? (via @fourfoldway)

Hisako Koyama, the Woman Who Stared at the Sun

posted by Jason Kottke   May 26, 2021

In the history of science, there are women who have made significant contributions to their field but haven’t gotten the recognition that their male peers have. The field of astronomy & astrophysics in particular has had many female pioneers — Vera Rubin, Cecilia Payne-Gaposchkin, Annie Jump Cannon, Nancy Grace Roman, Maria Mitchell, Jocelyn Bell Burnell, Henrietta Swan Leavitt, Caroline Herschel, Williamina Fleming, and many others. Add to that list Hisako Koyama, a Japanese astronomer whose detailed sketches of the Sun over a 40-year period laid the foundation for a 400-year timeline of sunspot activity, which has aided researchers in studying solar cycles and magnetic fields.

Ms. Koyama was a most unusual woman of her time. As a scientist, she bridged the amateur and professional world. She preferred “doing” activities: observing, data recording, interacting with the public, and writing. No doubt many Japanese citizens benefited from personal interaction with her. The space and geophysics community continues to benefit from her regular and precise observations of the Sun. Although we know very little of her young personal life other than she was relatively well educated and had a father who supported her desire to view the skies by providing a telescope, we can see from snippets in Japanese amateur astronomy articles that she had a passion for observing, as revealed in her 1981 article: “I simply can’t stop observing when thinking that one can never know when the nature will show us something unusual.”

Here are a few of her sunspot sketches, the top two done using her home telescope and the bottom one using the much larger telescope at the National Museum of Nature and Science (that shows the largest sunspot of the 20th century):

drawings of sunspots on the Sun by Hisako Koyama

drawings of sunspots on the Sun by Hisako Koyama

(via the kid should see this)

The Final Border Humanity Will Never Cross

posted by Jason Kottke   May 11, 2021

This video focuses on one of my favorite astrophysics facts: 94% of the observable universe is permanently unreachable by humans. (Unless we discover faster-than-light travel, but that’s fantasy at this point.)

This expansion means that there is a cosmological horizon around us. Everything beyond it, is traveling faster, relative to us, than the speed of light. So everything that passes the horizon, is irretrievably out of reach forever and we will never be able to interact with it again. In a sense it’s like a black hole’s event horizon, but all around us. 94% of the galaxies we can see today have already passed it and are lost to us forever.

“Since you started watching this video, around 22 million stars have moved out of our reach forever.” And future generations, billions of years from now, won’t even be able to see any other galaxies or detect cosmic background radiation, making knowledge about the Big Bang impossible.

The Otherworldly Sounds of Ice

posted by Jason Kottke   May 05, 2021

The holes drilled into Arctic, Antarctic, and glacial ice to harvest ice cores can be up to 2 miles deep. One of my all-time favorite sounds is created by dropping ice down into one of these holes — it makes a super-cool pinging noise, as demonstrated in these two videos:

Ice makes similar sounds under other conditions, like if you skip rocks on a frozen lake:

Or skate on really thin ice (ok this might actually be my favorite sound, with apologies to the ice core holes):

Headphones are recommended for all of these videos. The explanation for this distinctive pinging sound, which sounds like a Star Wars blaster, has to do with how fast different sound frequencies move through the ice, as explained in this video:

(via the kid should see this)

An Animated Primer on Black Holes

posted by Jason Kottke   Apr 28, 2021

You’re probably aware that black holes are weird. You can learn more about just how extremely odd they are by watching this animated primer on black holes by Kurzgesagt. The explanation about how long black holes live starting at ~9:30 is legitimately mindblowing — that hourglass metaphor especially.

Wobbling Muons May Hint at Unknown Forces

posted by Jason Kottke   Apr 08, 2021

Muon Ring

The preliminary results of a study of elementary particles at Fermilab and elsewhere show that the behavior of particles called muons deviates from standard physical theories, indicating that previously unknown forces are at work.

Evidence is mounting that a tiny subatomic particle seems to be disobeying the known laws of physics, scientists announced on Wednesday, a finding that would open a vast and tantalizing hole in our understanding of the universe.

The result, physicists say, suggests that there are forms of matter and energy vital to the nature and evolution of the cosmos that are not yet known to science.

“This is our Mars rover landing moment,” said Chris Polly, a physicist at the Fermi National Accelerator Laboratory, or Fermilab, in Batavia, Ill., who has been working toward this finding for most of his career.

The particle célèbre is the muon, which is akin to an electron but far heavier, and is an integral element of the cosmos. Dr. Polly and his colleagues — an international team of 200 physicists from seven countries — found that muons did not behave as predicted when shot through an intense magnetic field at Fermilab.

The aberrant behavior poses a firm challenge to the Standard Model, the suite of equations that enumerates the fundamental particles in the universe (17, at last count) and how they interact.

“This is strong evidence that the muon is sensitive to something that is not in our best theory,” said Renee Fatemi, a physicist at the University of Kentucky.

Update: At Quanta Magazine, Natalie Wolchover dives deeper into the preliminary results and what they might mean.

The Secret of Synchronization

posted by Jason Kottke   Apr 02, 2021

What do swaying bridges, flashing fireflies, clapping audiences, the far side of the Moon, and beating hearts have in common? Their behavior all has something to do with synchronization. In this video, Veritasium explains why and how spontaneous synchronization appears all the time in the physical world.

I was really into the instability of the Millennium Bridge back when it was first opened (and then rapidly closed), so it was great to hear Steven Strogatz’s explanation of the bridge’s failure.

Oh, and do go play with Nicky Case’s firefly visualization to see how synchronization can arise from really simple rules.

What Would We Experience If Earth Spontaneously Turned Into A Black Hole?

posted by Jason Kottke   Nov 05, 2020

Let’s say the Earth turned into a black hole. What would happen to someone standing on the surface and for how long would it happen? From Ethan Siegel:

As spectacular as falling into a black hole would actually be, if Earth spontaneously became one, you’d never get to experience it for yourself. You’d get to live for about another 21 minutes in an incredibly odd state: free-falling, while the air around you free-fell at exactly the same rate. As time went on, you’d feel the atmosphere thicken and the air pressure increase as everything around the world accelerated towards the center, while objects that weren’t attached to the ground would appear approach you from all directions.

Universe Sandbox

posted by Jason Kottke   Feb 14, 2020

Universe Sandbox is a interactive space & gravity simulator that you can use to play God of your own universe.

You can create star systems: “Start with a star then add planets. Spruce it up with moons, rings, comets, or even a black hole.” You can collide planets and stars or simulate gravity: “N-body simulation at almost any speed using Newtonian mechanics.” You can model the Earth’s climate, make a star go supernova, or ride along on space missions or see historical events.

I found Universe Sandbox after watching this video about what would happen if the Earth got hit by a grain of sand going 99.9% the speed of light (spoiler: not much). This game/simulator/educational tool is only $30 but I fear that if I bought it, I would never ever leave the house again.

New Solar Telescope Shows the Sun’s Surface in Unprecendented High Resolution Images & Video

posted by Jason Kottke   Jan 29, 2020

Sun's Surface

Sun's Surface

The National Science Foundation has just released the very first images of the Sun taken with the new Inouye Solar Telescope in Hawaii. They are the highest resolution images ever taken of the Sun’s surface, showing three times more detail than was possible using previous imaging techniques. Those cells you see in the image…they’re each about the size of Texas.

Building a telescope like this is not an easy task — there’s a lot of heat to deal with:

To achieve the proposed science, this telescope required important new approaches to its construction and engineering. Built by NSF’s National Solar Observatory and managed by AURA, the Inouye Solar Telescope combines a 13-foot (4-meter) mirror — the world’s largest for a solar telescope — with unparalleled viewing conditions at the 10,000-foot Haleakala summit.

Focusing 13 kilowatts of solar power generates enormous amounts of heat — heat that must be contained or removed. A specialized cooling system provides crucial heat protection for the telescope and its optics. More than seven miles of piping distribute coolant throughout the observatory, partially chilled by ice created on site during the night.

Scientists have released a pair of mesmerizing time lapse videos as well, showing ten minutes of the roiling surface of the Sun (wide angle followed by a close-up view) in just a few seconds:

The Daniel K. Inouye Solar Telescope has produced the highest resolution observations of the Sun’s surface ever taken. In this movie, taken at a wavelength of 705nm over a period of 10 minutes, we can see features as small as 30km (18 miles) in size for the first time ever. The movie shows the turbulent, “boiling” gas that covers the entire sun. The cell-like structures — each about the size of Texas — are the signature of violent motions that transport heat from the inside of the sun to its surface. Hot solar material (plasma) rises in the bright centers of “cells,” cools off and then sinks below the surface in dark lanes in a process known as convection. In these dark lanes we can also see the tiny, bright markers of magnetic fields. Never before seen to this clarity, these bright specks are thought to channel energy up into the outer layers of the solar atmosphere called the corona. These bright spots may be at the core of why the solar corona is more than a million degrees!

Man, I hope we get some longer versions of these time lapses — I would watch the hell out of one that ran for 10 minutes. (via moss & fog)

An Astronomer Explains Black Holes in 5 Levels of Increasing Complexity

posted by Jason Kottke   Jan 21, 2020

In this video from Wired’s 5 Levels series, NASA astronomer Varoujan Gorjian explains the concept of black holes to five different people, ranging from a five-year-old to a college student to a Caltech astrophysicist.

A research astronomer at NASA’s Jet Propulsion Laboratory, Grojian specializes in — and I’d just like to pause here to emphasize that this is the official title of his research group at JPL — the structure of the universe. Which means the guy not only knows about event horizons and gravitational lensing but stuff like tidal forces (what!), x-ray binaries (hey now!), and active galactic nuclei (oh my god!). Seriously, the guy’s knowledge of black holes is encyclopedic.

Gorjian lost me somewhere in the middle of his conversation with the grad student.

How Do You Move a Star? Stellar Engines!

posted by Jason Kottke   Dec 30, 2019

In this episode of Kurzgesagt, they’re talking about building engines powerful enough to move entire stars, dragging their solar systems along with them.

At some point we could encounter a star going supernova. Or a massive object passing by and showering earth with asteroids.

If something like this were to happen we would likely know thousands, if not millions of years in advance. But we still couldn’t do much about it.

Unless… we move our whole solar system out of the way.

Kurzgesagt did something interesting for this one. Instead of relying on already available sources, they commissioned physicist Matthew Caplan to write a paper about a novel stellar engine design, a massive contraption that could theoretically move the solar system a distance of 50 light years over 1 million years.

Stellar engines, megastructures used to control the motion of a star system, may be constructible by technologically advanced civilizations and used to avoid dangerous astrophysical events or transport a star system into proximity with another for colonization.

Is this the first scientific paper published in a peer-reviewed journal commissioned by a YouTube channel? The 2019 media landscape is wild.

Cecilia Payne-Gaposchkin, a Giant of Physics

posted by Jason Kottke   Dec 17, 2019

Prompted by this Facebook post, I have been reading about astrophysicist Cecilia Payne-Gaposchkin, who should be more widely known than she is. From a piece last year in Cosmos:

Cecilia Payne, born on May 10, 1900, in Wendover, England, began her scientific career in 1919 with a scholarship to Cambridge University, where she studied physics. But in 1923 she received a fellowship to move to the United States and study astronomy at Harvard. Her 1925 thesis, Stellar Atmospheres, was described at the time by renowned Russian-American astronomer Otto Struve as “the most brilliant PhD thesis ever written in astronomy”.

In the January, 2015, Richard Williams of the American Physical Society, wrote: “By calculating the abundance of chemical elements from stellar spectra, her work began a revolution in astrophysics.”

Even though she completed her studies at Cambridge, she was not awarded a degree because the university did not give degrees to women. That’s when she decided to move to the US, where Harvard offered greater educational opportunities and a “collection of several hundred thousand glass photographs of the night sky” that Payne-Gaposchkin was uniquely qualified to analyze.

Miss Payne applied the new theories of atomic structure and quantum physics to her analysis of stellar spectra. No one at the Harvard Observatory had yet attempted such an investigation, as no one there possessed the necessary background. She, in contrast, had learned the complex architecture of the “Bohr atom” directly from Niels Bohr, winner of the 1922 Nobel Prize in physics. She had also followed the work of Indian physicist Meg Nad Saha of Calcutta, the first person to link the atom to the stars. Saha maintained that the line patterns in stellar spectra differed according to the temperatures of the stars. The hotter the star, the more readily the electrons of its atoms leaped to higher orbits. With sufficient heat, the outermost electrons broke free, leaving behind positively charged ions with altered spectral signatures.

Building on Saha’s base, with insights gained from a couple of her professors in England, Miss Payne selected specific spectral lines to examine. Then she estimated their intensities in hundreds of stellar spectra. Element by element she gauged, plotted, and calculated her way through the plates to take the temperatures of the stars.

Her groundbreaking work on spectra, laid out in her Ph.D thesis published when she was just 25, puts Payne-Gaposchkin in the same league as some other physics heavy hitters.

Her discovery of the true cosmic abundance of the elements profoundly changed what we know about the universe. The giants — Copernicus, Newton, and Einstein — each in his turn, brought a new view of the universe. Payne’s discovery of the cosmic abundance of the elements did no less.

Incredible Display of Ice Crystal Halos Around the Sun in the Swiss Alps

posted by Jason Kottke   Dec 05, 2019

Ice Halos

This is a photo of several ice crystal halos around the Sun taken by Michael Schneider in the Swiss Alps with an iPhone 11 Pro. It. Is. Absolutely. Stunning. I can barely write more than a few words here without stealing another peek at it. According to Schneider’s post (translated from German by Google), this display developed gradually as he waited for a friend as some icy fog and/or clouds were dissipating at the top of a Swiss ski resort and he was happy to capture it on his new phone.

Using this site on atmospheric optics, Mark McCaughrean helpfully annotated Schneider’s photo to identify all of the various halos on display:

Ice Halos 02

Displays like this are pretty rare, but Joshua Thomas captured a similar scene in New Mexico a few years ago and Gizmodo’s Mika McKinnon explained what was going on.

Ice halos happen when tiny crystals of ice are suspended in the sky. The crystals can be high up in cirrus clouds, or closer to the ground as diamond dust or ice fog. Like raindrops scatter light into rainbows, the crystals of ice can reflect and refract light, acting as mirrors or prisms depending on the shape of the crystal and the incident angle of the light. While the lower down ice only happens in cold climates, circus clouds are so high they’re freezing cold any time, anywhere in the world, so even people in the tropics mid-summer have a chance of seeing some of these phenomena.

Explaining the optics of these phenomena involves a lot of discussing angular distances.

So so so so cool.

Neutron Stars and Nuclear Pasta. Yummy!

posted by Jason Kottke   Nov 13, 2019

The latest video from Kurzgesagt is a short primer on neutron stars, the densest large objects in the universe.

The mind-boggling density of neutron stars is their most well-known attribute: the mass of all living humans would fit into a volume the size of a sugar cube at the same density. But I learned about a couple of new things that I’d like to highlight. The first is nuclear pasta, which might be the strongest material in the universe.

Astrophysicists have theorized that as a neutron star settles into its new configuration, densely packed neutrons are pushed and pulled in different ways, resulting in formation of various shapes below the surface. Many of the theorized shapes take on the names of pasta, because of the similarities. Some have been named gnocchi, for example, others spaghetti or lasagna.

Simulations have demonstrated that nuclear pasta might be some 10 billion times stronger than steel.

The second thing deals with neutron star mergers. When two neutron stars merge, they explode in a shower of matter that’s flung across space. Recent research suggests that many of the heavy elements present in the universe could be formed in these mergers.

But how elements heavier than iron, such as gold and uranium, were created has long been uncertain. Previous research suggested a key clue: For atoms to grow to massive sizes, they needed to quickly absorb neutrons. Such rapid neutron capture, known as the “r-process” for short, only happens in nature in extreme environments where atoms are bombarded by large numbers of neutrons.

If this pans out, it means that the Earth’s platinum, uranium, lead, and tin may have originated in exploding neutron stars. Neat!