If you want to know about tensors or spinors, eigenchris is an excellent teacher. He is also your guy for quantum mechanics. You may not be ready. You may not even be worthy. Watch anyway. And learn.
Youtube Channel: eigenchris
Tag Archives: physics
Fly-by-ear: The SIMONA flight simulator and the LN-3 INS
FlyByMax presents two terrific videos on how real and perceived forces play into flight simulator and inertial guidance systems. Simulators don’t just mimic the motions of their vehicles. Designers have to use the human vestibular and visual systems to mix the physical movements and scene projections to maximize realism.
Youtube Channel: FlyByMax
Talking Giants: Dirac and De Broglie in their own voice
Two founders of quantum mechanics speak. Dirac is interviewed (and too frequently interrupted) by Friedrich Hund, himself an eminent physicist known to spectroscopists everywhere. De Broglie lived to 94 and his post-Nobel career included the premier seat at Académie Française. Dirac had a reputation as a man of very few words. 80 years old at the time of filming, one senses that this discussion was difficult for him.
Youtube Channel: mehranshargh
Youtube Channel: Nomen Nominandum
A Shaft of Gold When All Around is Dark: JWST is operational
One last glorious gasp from a decayed and dead civilization. JWST’s Mid Infrared Instrument observes Stephan’s Quintet. What else will it be allowed to do before the American Taliban takeover?
JWST’s MIRI looks at Stephan’s Quintet. Courtesy NASA and the Space Telescope Science Institute
Astrophysics at Ludicrous Speed: But Why? on stellar collapse
It should be no surprise that aging scientists from all fields gravitate (ha!) to astronomy as we get more interested in the grand fates of things. Fortunately there are many sites and channels to scratch that itch, giving us a perhaps too comfortable view of complex material. The life and death of stars is an example where the high level explanations of gravity versus fusion do work but where the many omitted details cause midnight befuddlement. Where does the energy come from? Where does it go? Wait… how fast – Relativistic speeds?
Anonymous Youtuber “But Why?” breaks the barrier with this beautiful video on the collapse of very big stars – the kind that leave neutron stars or black holes in their wake. It isn’t all symmetric implosions and classical rebounds and the thought of a giant object collapsing 5000-km in a tenth of a second boggles the mind. The depth of detail is breathtaking, the amount of research inspiring, and taught me much new physics that I incorrectly thought I already knew.
Youtube Channel: But Why?
Piece of the Action: The crazy engineering of the piano key
Playing the piano is damnably hard. I have accepted that I will never practice consistently or wisely enough to reach my original wildly unrealistic goals of competence and am contenting myself with slow progress and occasional discoveries. Coaxing a good sound requires talent, coordination, flexibility, and freedom of movement. There’s nothing that can be done about the first item but occasionally something in the joints unsticks enabling a small improvement in the rest. I feel kinship with weekend athletes who get that occasional moment of grace amid hours of futility.
One of the many frustrations is pressing a key in the same place with the same pressure five times in a row and hearing no sound two of those times. The hammer misses the strings by a fraction of a millimeter and flops back with a click and a dull thud. This makes any kind of phrasing next to impossible for the duffer. He either settles for good enough or goes nuts trying to adapt as the instrument itself changes with the time of day and the weather. It never bothers the professionals who figure it out on the fly.
The piano action itself is a bizarre marvel of wood, felt, physics, and prayer. It is surprising that it works at all and there are eighty eight of the bloody things that have to work consistently. It is a lot to ask, perhaps too much. Robert Grijalva of the University of Michigan explains it in painstaking detail using a model of his own invention. For those with less time, a Dutch animator posting as Hoe Ishetmoegelijk (hoe is het moegelijk = how is it possible) has a concise summary.
Youtube Channel: Robert Grijalva
Youtube Channel: Hoe Ishetmoegelijk
An Impey Trifecta: Dark matter, strange correlations, and observing time
The online astronomy office hours from the UofA continue apace. Every week Prof. Chris Impey answers ex tempore a mix of questions from planetary science to the fate of the universe from a thirsty audience across the globe. A large Indian contingent stays up until the wee small hours of their morning to join in. Part of the fun is pausing the video and trying to figure out the answer from basic considerations before resuming. It is fun to be right but more instructive to be wrong. I’ve been moved to send in three questions over the past couple of sessions and all have been answered.
- When in relation to the Big Bang did dark matter originate?
- There is a surprising correlation between supermassive galactic black hole size and the population of old stars in a galaxy. Can telescopes now resolve individual stars in distant galaxies well enough to distinguish old from new to establish this connection?
- Observational results come from the successful. How do astronomers get precious telescope time?
Youtube Channel: Astronomy State of the Art
Backyard history: Southern California’s impact on astronomy
Silicon Valley has reshaped the earth, Hollywood has driven our perceptions of it, and not always for the better. Less well known is the outsized role California has played in understanding our universe. Mt. Wilson, Mt. Palomar, and their astronomers have had a Copernican impact on where we stand in the grand scheme of things. The word ‘vision’ gets bandied about a lot these days but George Ellery Hale had it in spades. Here’s how the two observatories that housed Hubble, Humason, Shapley, Zwicky, Baade, Rubin, and Schmidt came to be.
The third video from Corning’s Museum of Glass shows that the path to science is not always smooth and that learning from mistakes is the norm. The original 200 inch pyrex disk for the Palomar primary did not go according to plan and had to be recast. The second attempt succeeded and even so, it took ten years of painstaking grinding and polishing at Caltech before it was ready for use.
Youtube Channel: Palomar Observatory
Youtube Channel: Irish Astronomy
https://www.youtube.com/watch?v=BL0ZGjF6DrA
Youtube Channel: Corning Museum of Glass
The time is out of joint: Chris Impey on the tick-tick-tock of the stately clock
Steven Weinberg wrote a famous book, “The First Three Minutes” on the early stages of the universe. The same universe became transparent to light some 370,000 years later. There are other landmarks in post-Big Bang time going down to bewildering fractions of a second.
But the early universe was very hot, very dense, and gravitationally very different from the comfortable-to-us 1 g we experience today on the surface of the earth. Einstein has convincingly shown that spacetime is accordingly divorced from that human experience. Clocks, for example, are affected by gravity and satnav constellations have to take this into account. Did the first three minutes flow the same way three minutes flow in the here and now? I sent that question to Chris Impey’s online office hour and he kindly answered. It is a tantalizing response and one that will require substantial further study to fully appreciate – perhaps finally diving into the guts of GR. It makes me wonder even more intensely why we anthropomorphize those intervals the way we do.
Youtube Channel: Astronomy State of the Art
Composer Toru Takemitsu has set the general idea to music.
Youtube Channel: Orquesta Sinfónica de Xalapa
COVID’s Metamorphoses: RCSB Coronavirus resources
The CDC and WHO are giving us good advice on what do in this Plague Year. The Research Collaboratory for Structural Bioinformatics (RCSB) is showing us the molecule causing the havoc. Check out the structures of the various flavors of Coronavirus at The Protein Database (PDB). Click on the images, most of which will go to detailed pages including 3D models that can be spun in the browser. Knowledge will be power in dealing with this beast and let’s offer thanks to the research groups who took the lead in characterizing it which must have come at considerable risk to themselves. When it mutates, and it will, they and others will undoubtedly don their capes and do the measurements again.
It is damnably, horrifyingly beautiful in David Goodsell’s artistic rendering of it infecting a lung:
Acknowledgement: Illustration by David S. Goodsell, RCSB Protein Data Bank; doi: 10.2210/rcsb_pdb/goodsell-gallery-019
License: CC-BY-4.0
Image used unmodified and there is no endorsement from or by the artist