https://mastodon.social/@pomarede/112339170146519848 pomarede@mastodon.social - Taylor Swift as an hypermagnetized neutron star
#TaylorSwift #astrophysics #Swifties #neutron #star #neutronstar #magnetar #physics #astronomy #astrodon #meme #science #memes #sciencememes #space #STEM
And now for something completely different
#Physics #Mathematics #Chaos #Newton #deGrasseTyson #Uncomputability
https://spore.social/@minouette/112270075937635916 minouette@spore.social - April 14 has been designated World Quantum Day in honour of Planck’s Constant which can be rounded to h~ 4.14×10−15 eV·s (and some folks write April 14 as 4/14*). Planck’s constant comes up a lot in quantum mechanics; for instance a photon’s energy is h times its frequency). So I thought I would share Feynman Bauhaus.
🧵1/n
#linocut #printmaking #physics #Bauhaus #quantumMechanics #FeynmanDiagram #penguinDiagram #particlePhysics #sciart #WorldQuantumDay
Fermilab @Fermilab
Why does observing a particle immediately collapse its wave function? How does it even know someone is observing it? Stay tuned all week as we answer more of your #quantum questions for World Quantum Day!
#askfermilab #WorldQuantumDay #Physics
@sqmscenter @doescience
https://twitter.com/i/status/1778795298594107883
String theory takes a spanking :)
So first of all, correct, the beautiful ideas came out of string theory. But that was not the original promise of string theory. The original promise was to describe the physics of this universe, unify all forces of nature, the three forces, electromagnetic, strong and weak described by the standard model and quantum theory of gravity. This has not happened. And now we hear that actually was not such a big deal. It's actually such a big thing. We've learned so much more.
It's like, you know, I tried to think of a good analogy. It's like, remember Moses? He took Israelites out of Egypt. Mm hmm. And he told them that he will lead them to the promised land. Yes. So imagine Moses after 40 years of wandering in the desert, you would say, you know, guys, you know, this idea of a promised land is not such a big thing. Look how much we've learned. We've learned about the desert. We've learned so much about the sand.
[Interviewer: That's a great analogy.]
Who cares about the promised land? What do you think would people say to him? And yet here we are. This is called, by the way, you mentioned this expression, moving the goalposts. This is not moving goalposts. This is going to a different stadium. It's starting to play a different game. Like you used to play soccer at one stadium. Then you go to another stadium. You start playing baseball and you say, no, we are playing soccer. We're still playing soccer. Yes, yes, yes. Stating that your original goal is not meaningful.
It did not work out. It did not work out. How about just starting with that? It did not work out unequivocally, not by saying the next 10 years [it will].
A #mini-planet orbiting in the frigid #outer reaches of the #solarsystem has a #Saturn-like #ring of #dust and #debris that #defies the rules of #physics, a new study has #revealed.
The planet in question is called #Quaoar and it's the #seventh largest of the known #dwarf #planets of which #Pluto is the #king. #Discovered in #2002 and about 697 miles wide (1,121 kilometers), Quaoar is one of the so-called #trans-Neptunian objects, small planets orbiting #beyond the solar system's outermost planet #Neptune.
Residing in the #KuiperBelt, the doughnut-shaped ring of rocky and icy debris in the outer solar system, Quaoar is a proud owner of its own #moon, the 100-mile-wide (160 km) #Weywot. And a recent observation campaign revealed that it also has a ring of material in its orbit.
That by itself wouldn't be so special. The gas giant Saturn is known to possess a whole series of rings. #Jupiter, Neptune and #Uranus also have some. One other trans-Neptunian object — #Haumea — has been found to have a ring, and the space rock #Chariklo that orbits between #Saturn and #Uranus also has one. So what exactly sets Quaoar's ring apart?
Related: Dwarf planets: science & facts about the solar system’s smaller worlds
Quaoar's ring is at a very unusual #distance from its parent body. In fact, before astronomers discovered Quaoar's ring in observations from several telescopes conducted between 2018 and 2021, they had thought that it was impossible for a ring to exist at such a distance. With a radius of about 2,420 miles (3,885 km) from Quaoar's center, the ring is too far away from the dwarf planet that its gravity should no longer be able to keep the material dispersed. Instead, it should coalesce under its own gravity and form another moon, just like Weywot. By not having done that, the ring has breached what astronomers call the Roche limit, the first known ring around a #celestial body to have done so.
"What is so intriguing about this discovery around Quaoar is that the ring of material is much farther out than the Roche limit," Giovanni Bruno, an astronomer at Italy's National Institute for Astrophysics (INAF) and one of the authors of the paper, said in a European #Space Agency (ESA) statement. "As a result of our observations, the classical notion that dense rings survive only inside the Roche limit of a planetary body must be thoroughly revised."
The ring was discovered during a series of occultations, essentially eclipses, when Quaoar passed between Earth and several more distant but much brighter stars. When an occultation occurs, the light of the background star temporarily dims. The effect is only visible to very sensitive telescopes and is frequently used to detect exoplanets orbiting stars in our Milky Way galaxy, which is why ESA's exoplanet hunter Cheops was among the telescopes watching these Quaoar occultations.
When astronomers analyzed the data, they realized that apart from the main dip in the background stars' brightness, they could detect two smaller drops. Since drops occurred before and after the main occultation, respectively, the researchers thought that Quaoar must be surrounded with a ring.
Several Earth-based telescopes also observed the occultations with similar results, but Cheops' data were particularly valuable as they proved that the odd dimmings were not caused by the effects of Earth's atmosphere.
https://www.space.com/mysterious-ring-around-dwarf-planet-puzzles-astronomers
"Antimatter: Scientists freeze positronium atoms with lasers."
Whoa.
"Positronium" has a negatively charged electron and a positively charged antimatter electron, which is called a positron. A regular hydrogen atom is made up of a positively charged proton and negatively charged electron.
So you get something like an atom, with a negatively charged electron and a positively charged particle, it's just that the positively charged particle is an antielectron (positron) instead of a proton. And because an antielectron (positron) has the same mass as a regular electron, the combination is lighter than a proton-electron pair, also known as a hydrogen atom.
I didn't know positronium even existed until I read this (you all have probably know for ages, huh?) so I did some digging to learn more about it. The way the process works is, first the "atom smasher" (really subatomic particle smasher) at CERN smashes subatomic particles together, and if the collisions are sufficiently high-energy, some of that energy (according to the famous E = mc^2 formula) gets converted into matter -- and not just any matter but particle-antiparticle pairs.
The next step is to slow them down. CERN has an Antiproton Decelerator which evidently can also slow down antielectrons (positrons).
"The Antiproton Decelerator is a ring composed of bending and focussing magnets that keep the antiprotons on the same track, while strong electric fields slow them down. The spread in energy of the antiprotons and their deviation from their track is reduced by a technique known as 'cooling'. Antiprotons are subjected to several cycles of cooling and deceleration until they are slowed down to around a tenth of the speed of light. A newer deceleration ring, ELENA (Extra Low ENergy Antiproton), is now coupled with the Antiproton Decelerator. This synchrotron, with a circumference of 30 metres, slows the antiprotons even more, reducing their energy by a factor of 50, from 5.3 MeV to just 0.1 MeV. An electron cooling system also increases the beam density. With ELENA, the number of antiprotons that can be trapped increases by a factor of 10 to 100."
The next step involves trapping the antielectrons in a Penning-Malmberg trap. This is complicated. Let's just say it works by using a combination of magnetic and electric fields to control the trajectory of the particles.
The next step involves producing positronium by combining the antielectrons (positrons) with regular electrons. This is done by directing them into silicon (silicon dioxide) with special "nanochannels" in it. I don't understand how this works. You would think funneling a boatload of antimatter into regular matter would just cause the antimatter and regular matter to meet and annihilate. But the silicon dioxide with the "nanochannels" is "porous" in such a way that a "quantum confinement" effect takes place that allows the antielectrons (positrons) to combine with regular electrons.
Finally we get to the step this news article is about: the laser cooling.
The way laser cooling works is by directing lasers at a material from from all 6 directions: all 4 sides plus above and below. The laser light is at a frequency that matches an energy transition of the atom. If positronium can be called an "atom". It can be treated like an "atom" for laser cooling purposes. Atoms have energy levels and when light comes in at the same frequency as a transition between energy levels, the atom can absorb the energy, in the form of absorbing a photon, and make the energy transition. Later it can "fall back" to the lower energy state and re-emit the photon. The key is that the atom absorbs light from a particular direction but emits it in a random direction. Because absorbing and emitting photons changes the momentum of the atom, this reduces the momentum of the particle in the direction of the laser. By doing lasers in all 6 directions, a cooling effect can be achieved on the atoms. In this experiment they specifically say they used a alexandrite laser that produces 243-nanometer wavelegth light, that corresponds to the transition between the ground state and the next energy level above the ground state.
The cooling effect is further enhanced with a Doppler effect. When an atom is moving towards a laser, light that it emits is blueshifted, according to its velocity. The same is true of light that it absorbs. By tuning the laser to a frequency slightly higher (or alternatively, to a wavelength slightly lower) than the frequency normally absorbed by the atom, the setup can be made so the laser's photons are only absorbed by atoms moving towards the laser.
In this experiment they reported they managed to drop the temperature of the positronium from 380 kelvin to 170 kelvin. By human standards, that means going from very hot (225 Fahrenheit / 105 Celsius) to extremely cold (-150 Fahrenheit / - 100 Celsius).
They want to make it even colder. Maybe that is made difficult by the fact that positronium usually only lasts for 142 nanoseconds before it annihilates into 3 gamma rays?
Oh wait, did I say positronium has only one ground state? It actually has two: one that lasts 142 nanoseconds and one that lasts 125 picoseconds. Remember, your metric prefixes go milli-, micro-, nano-, pico-, each one a factor of 1,000 smaller than the next. All the laser cooling was done using the long-lived ground state, the 142 nanosecond one (which is called 1^3 S -- the other is called 1^1 S. The laser cooling was done using the 1^3 S to 2^3 P transition.)
What does all this portend for the future?
Being able to sufficiently supercool positronium would enable experiments with precision spectroscopy on antimatter, measuring all the light that gets emitted from all the energy level transitions with extreme precision. This would enable testing of the QED theory (quantum electrodynamics) to an unprecedented level. "Bound state" QED, where you have particles bound together, such as here where we have an antielectron (positron) and a regular electron together, predicts these energy transitions using the universe's fine structure constant (that dimensionless constant you've heard of that is approximately 1/137). So this would enable deep testing of QED and precision measurement of the fine structure constant, as well as matter-antimatter symmetry, because we could see if the spectra for antielectrons (positrons) is the same as regular electrons.
You would think the spectra for antielectrons (positrons) would be exactly the same as regular electrons, and current Standard Model theory predicts it will. But, matter and antimatter are not always perfectly symmetrical mirror images of each other. In fact it's obvious they can't be, because we live in a universe with matter, a consequence of an asymmetry between matter and antimatter during the big bang.
If you're wondering why the material needs to be super cold for high precision spectroscopy, it's because the same Doppler effect mentioned earlier causes spectral lines to spread out when a material has a lot of kinetic energy and along with that, a lot of variation in the velocities of the particles.
Finally, there's the possibility of a gamma-ray laser. So, there's a theory that if you could cool positronium all the way down to being a Bose-Einstein condensate, then the "atoms" of positronium would become coherent in such a way that when they annihilate and release their 3 (in the case of the long-lived 1^3 S ground state positronium) or 2 (in the case of the short-lived 1^1 S ground state positronium) gamma rays, the gama rays can stimulate other "atoms" of positronium to annihilate as well. Bose-Einstein condensate is a state of matter near absolute zero in temperature where atoms enter the same quantum state and share a wave function. This would result in the emission of coherent gamma-ray light -- a gamma-ray laser, in other words. A gamma-ray laser has never existed before.
Not exactly a Warp Drive...but...
https://www.sciencealert.com/antimatter-could-unlock-a-radical-new-future-of-interstellar-travel
