Hey folks! I’ve appeared on yet another podcast! Fortunately, for those who are tired of me talking about invisibility, this one is about cats, and related to my previous book on Falling Felines and Fundamental Physics.
I’m part of an episode discussing the righting reflex. Click on the image above to go to the episode, or this link here. Thanks again to Amanda for having me on the show!
Fate has led me to another invisibility story while looking for something completely different! This gives me one more opportunity to remind people that my book on invisibility is available while I blog about this story.
One of the very oldest stories about invisibility in the history of humanity is the story of Perseus from ancient Greek folklore. Perseus, the son of Zeus, is given gifts by the gods to accomplish his quest. One of these is the Cap of Hades, that confers invisibility on the wearer; Perseus uses it to sneak up on Medusa and her immortal sisters and escape safely with her head. This story has been told in many versions, though one of the most detailed was written in the first or second century CE in the Bibliotheca of an author known as pseudo-Apollodorus. (For years, scholars thought that Apollodorus wrote the Bibliotheca, but now believe this not to be true, so the unknown author is simply known as pseudo-Apollodorus.)
With this in mind, you’d think that I would’ve found a significant number of modern stories inspired by Perseus, but so far I’ve only found one: “Perseus Had a Helmet,” by Richard Sale, which appeared in the very first issue of The Magazine of Fantasy, Fall 1949. (I’ll give a few spoilers again, so please read the story first if you’re concerned.)
Some time ago, I read Rogue Moon (1960), by Algis Budrys, a classic science fiction novel about an alien deathtrap maze discovered on the moon and the man willing to die over and over again to discover its secrets. I found it fascinating, even though for some reason I never blogged about it. I’ve thought about looking up more of Budrys’ work, and after recently rereading his invisibility-related story “For Love,” I decided to give Hard Landing (1993) a try.
Hard Landing is a very unusual but compelling novel — it tells the story of alien explorers from another solar system who crash land on Earth and are forced to “go native,” and the ways they go about it.
Continue readingThe early years of quantum physics, from Einstein’s explanation of the photoelectric effect in 1905 through the introduction of the Schrödinger equation in 1926, was a remarkable time for science and filled with novel ideas, speculations, and experiments. In the teaching of physics, some of these results get more attention, and some absolutely beautiful experiments are not discussed as often as others, as they are not essential to understanding the phenomena, even if they were essential in proving them.
One example of this I’ve had on my mind for some time is the Franck-Hertz experiment, reported in 1914. This experiment was the first demonstration that the energy levels of atoms are quantized, and that an atom can only absorb or emit energy in discrete amounts referred to as “quanta.” I did the Franck-Hertz experiment as an undergraduate, and it has always stuck with me. A few years ago, I tried to track down the original paper, but found to my surprise that it was extremely difficult to find — even an attempt to acquire it through Interlibrary Loan failed! This week, however, I took another look, and managed to get the original paper in German and translate it, and wanted to share a description of it here.
Continue readingYou know what I haven’t talked about much lately? My own research! Well, today is a great day for it, because a paper I wrote with my student Ray Abney just came out in Physical Review A, titled “Nonradiating orbital motions.” It’s actually invisibility-related, and I thought I would say just a few words (and pictures) of what it’s all about!
So, one of the earliest physical phenomena studied that can be connected to invisibility is known today as a nonradiating source. The oxymoronic name refers to a source of electromagnetic radiation (or more generally other types of waves) that, in fact, does not produce any radiation at all.
This is counterintuitive because the mathematical formulas that describe electricity, magnetism and light, called Maxwell’s equations after their discoverer, predict that an oscillating electrical current will produce electromagnetic waves. All of our wireless communications technology is based on that principle; when you see a radio antenna, such as the mast radiator pictured below, you are looking at a metal structure that has an oscillating electrical current driven through it to produce radio waves.
Your cell phones produce a signal in a similar manner; they have an antenna for broadcasting and receiving. Apple infamously ran into trouble with the iPhone 4 when they changed the antenna design and put it around the edge of the case, causing dropped calls when people held the phone “wrong!”
If charges are accelerated more strongly, they can produce higher-energy electromagnetic waves such as X-rays. The Advanced Photon Source at Argonne National Laboratory takes advantage of this and sends electrons around an 1,100 meter ring at nearly the speed of light; the circular path of the electrons causes them to constantly shed X-rays that can be used for basic and applied research.
So it is widely known and assumed that accelerated electric charges produce electromagnetic radiation of some form. But this is not always the case!
Continue readingI knew Sasha was special from the moment I saw her. She was not only an absolutely beautiful feline, but she somehow radiated a calmness and wisdom to me in general that I have rarely seen in cats.
Sasha passed away last night after a long and happy life at nineteen years old. She was my ex-wife Beth’s companion, so I didn’t see her as much once we separated in 2016, but I feel the loss strongly nevertheless.
I wanted to share a few photos of her in this post and some of my favorite memories.
Continue readingI’ve been meaning to read a lot more popular science books outside of my field lately, in order to broaden my knowledge and just get back in the habit of reading that I fell out of during the Dark Times of 2020-2021. Fortunately, in recent months a number of my classic scicomm blogging friends (that I’ve now known for over a decade) have written books, and this has been a great opportunity and motivation to get reading again! The first one that I’ve finished is Pests (2022), by Bethany Brookshire.
Human beings are thoroughly familiar with animal pests, from the pizza rats of New York City to the raccoons of Chicago going through our garbage cans to the coyotes of, well, almost everywhere now, threatening family pets and small children. But are we really that familiar with those animals that we call “pests,” and do we really understand what a pest is?
Pests is an insightful and engrossing look at what it means to be a pest, and how that term is more a reflection of our own human biases and needs than of the animal’s nature. It looks at the stories and history of a wide variety of animals, from ubiquitous animals like rats, mice and pigeons to exotic animals like snakes and elephants and even those animals that we have taken into our home, like cats. It leaves off all the creepy crawly invertebrates like spiders and cockroaches, which would probably merit a book all on their own. (And I don’t miss them here!)
Continue readingThis is the last reblog of a classic invisibility story! I think I’ve got a couple more that I haven’t blogged before to follow. Want to keep up my “blog post a day” streak for as long as possible!
Let’s tackle another invisibility story! This one is a little different, in that it is a story about an imaginary invisible friend!
“The Handyman,” by Lester Barclay, appeared in the October 1950 issue of Fantastic Adventures. It is short and sweet, so this will be a very short blog post! Spoilers follow… you can read the story on archive.org in advance if you like.
View original post 590 more words
I found another invisibility story! This allows me to keep talking about invisibility for at least one more day, with a reminder that my book on the history and science of invisibility is now available.
This next invisibility story is a somewhat different creature than many of the previous ones we’ve discussed. Most of the tales I’ve considered have been science fiction, and dealt with the how and why of invisibility; “The Vanishing American,” by Charles Beaumont, is more of a parable. It appeared in the August 1955 issue of The Magazine of Fantasy and Science Fiction.
I will discuss some spoilers below, so go track down the story first if you’re worried about them!
Continue readingYou can find amazing and wonderful things when you browse old science journals. And when I say “old,” I don’t mean that you even have to go back very far. While I was tracking down an article in the journal Applied Optics from 1980, I came across a paper by R. E. Grojean, J. A. Sousa, and M. C. Henry1, “Utilization of solar radiation by polar animals: an optical model for pelts.”
Yes, it’s a paper that looks at whether the fur of polar bears works as a solar heat converter!
You would think that this would be a relatively simple question to answer. We’re not talking quantum physics, we’re talking polar bear fur, but the exact optical purpose of polar bear fur, if any, has been surprisingly controversial — and as far as I can tell has not been solved! Let’s take a look at the history, the science and the mystery.
Continue reading
The author of Skulls in the Stars is a professor of physics, specializing in optical science, at UNC Charlotte. The blog covers topics in physics and optics, the history of science, classic pulp fantasy and horror fiction, and the surprising intersections between these areas. 
Skulls in the Stars 