Christopher S. Baird
@christophersbaird.bsky.social
Associate Professor of Physics at West Texas A&M University. Author of the book, "The Top 50 Science Questions with Surprising Answers." Author of the website, "Science Questions with Surprising Answers." Researching quantum devices, lasers, and terahertz.
Related to the last plot, it always bugs me when books show a smooth curve that they fit to the plot of binding energy per nucleon as a function of number of nucleons (for the most stable nuclides). The wiggle is real and is there fore a good reason!
May 29, 2025 at 2:53 AM
Related to the last plot, it always bugs me when books show a smooth curve that they fit to the plot of binding energy per nucleon as a function of number of nucleons (for the most stable nuclides). The wiggle is real and is there fore a good reason!
I made this chart for a class I teach, showing various electric charge setups. I think that it shows the pattern well. An arbitrary charge configuration can be represented as a combination of these, and often the higher-order multipoles can be approximated to be zero.
#ITeachPhysics
#ITeachPhysics
May 7, 2025 at 4:57 PM
I made this chart for a class I teach, showing various electric charge setups. I think that it shows the pattern well. An arbitrary charge configuration can be represented as a combination of these, and often the higher-order multipoles can be approximated to be zero.
#ITeachPhysics
#ITeachPhysics
!["Where there is one common all-overriding end, there is no room for any general morals or rules... Where a few specific ends dominate the whole of [a totalitarian] society, it is inevitable that occasionally cruelty will become a duty; that acts which revolt all our feeling, such as the shooting of hostages or the killing of the old or sick, should be treated as mere matters of expediency; that the compulsory uprooting and transportation of hundreds of thousands should become an instrument of policy approved by almost everybody except the victims; or that suggestions like that of a 'conscription of women for breeding purposes' can be seriously contemplated." 1944, F.A. Hayek, Austrian-born British professor and winner of the Nobel Prize in Economics](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:vxtnapdf4umxdj3zb2adutys/bafkreiglh3zvkbyatawbsw2jqcbfvkcwmps27fnlldps3w5qj3shxm7ha4@jpeg)
There are various meiosis errors that can occur. In the error shown here, since Turner syn. girls rarely survive to birth, there is a greater chance of giving birth to a boy. When you take all errors into account and average, it's unlikely that the girl-boy ration at birth will be exactly 50%-50%.
May 6, 2025 at 3:46 PM
There are various meiosis errors that can occur. In the error shown here, since Turner syn. girls rarely survive to birth, there is a greater chance of giving birth to a boy. When you take all errors into account and average, it's unlikely that the girl-boy ration at birth will be exactly 50%-50%.
Fresnel lenses are fun to play with if you ever get a chance. As shown in the picture, a Fresnel lens is made by dividing it into sections and removing unneeded material from each section, leading to a thin lens.
You get a lens which seems unusually powerful for its size.
#ITeachPhysics
You get a lens which seems unusually powerful for its size.
#ITeachPhysics
May 5, 2025 at 6:07 PM
Fresnel lenses are fun to play with if you ever get a chance. As shown in the picture, a Fresnel lens is made by dividing it into sections and removing unneeded material from each section, leading to a thin lens.
You get a lens which seems unusually powerful for its size.
#ITeachPhysics
You get a lens which seems unusually powerful for its size.
#ITeachPhysics
!["Everything which might cause doubt [in a totalitarian state] about the wisdom of the government or create discontent will be kept from the people... all will be suppressed. There is consequently no field where the systematic control of information will not be practiced and uniformity of views enforced. This applies even to fields apparently most remote from any political interests and particularly to all the sciences, even the most abstract... Totalitarian control of opinion extends, however, also to subjects which at first seem to have no political significance." 1944, F.A. Hayek, Austrian-born British professor and winner of the Nobel Prize in Economics](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:vxtnapdf4umxdj3zb2adutys/bafkreihhjnheawmnpit4stcl2m6mt6g2wipdkwerpzr6wrlpur44e2l44a@jpeg)
Excessive consumption of genuine licorice (that hasn't been deglycyrrhizinated) causes dangerously high blood pressure and related problems because of a well-understood cascade of processes in the body. It can be found in licorice candy and herbal supplements that contain licorice root.
May 1, 2025 at 7:41 PM
Excessive consumption of genuine licorice (that hasn't been deglycyrrhizinated) causes dangerously high blood pressure and related problems because of a well-understood cascade of processes in the body. It can be found in licorice candy and herbal supplements that contain licorice root.
Saying that air is an electrical insulator oversimplifies the matter. Even at low voltages, air can indeed carry an electrical current, but you don't see it and the current is weak. This is why statically charged objects eventually end up uncharged. Their charge flows out into the air #ITeachPhysics
April 21, 2025 at 8:27 PM
Saying that air is an electrical insulator oversimplifies the matter. Even at low voltages, air can indeed carry an electrical current, but you don't see it and the current is weak. This is why statically charged objects eventually end up uncharged. Their charge flows out into the air #ITeachPhysics
I've been reading about the history of physics and have been amazed by how many contributors to physics fled Nazi Germany, Nazi Austria, and Fascist Italy. I had fun making this table to get all the info into one place. #ITeachPhysics
March 28, 2025 at 7:22 PM
I've been reading about the history of physics and have been amazed by how many contributors to physics fled Nazi Germany, Nazi Austria, and Fascist Italy. I had fun making this table to get all the info into one place. #ITeachPhysics
When you look at a transparent object, in some sense you are not looking directly at the object itself!
Rather, you're looking at images of the background and surrounding objects after having been distorted by refracting through and reflecting off of the object.
Rather, you're looking at images of the background and surrounding objects after having been distorted by refracting through and reflecting off of the object.
March 18, 2025 at 5:55 PM
When you look at a transparent object, in some sense you are not looking directly at the object itself!
Rather, you're looking at images of the background and surrounding objects after having been distorted by refracting through and reflecting off of the object.
Rather, you're looking at images of the background and surrounding objects after having been distorted by refracting through and reflecting off of the object.
This turned out better than I expected. Happy Pi Day!
March 14, 2025 at 11:22 PM
This turned out better than I expected. Happy Pi Day!
Although the rigorous mixing of gases that occurs in the atmosphere below 90 km makes the atmosphere mostly homogeneous, so that its composition is independent of height, the gases do partially separate out according to mass above 90 km, as caused by gravity.
February 27, 2025 at 8:09 PM
Although the rigorous mixing of gases that occurs in the atmosphere below 90 km makes the atmosphere mostly homogeneous, so that its composition is independent of height, the gases do partially separate out according to mass above 90 km, as caused by gravity.
A redshift means a shift to lower frequencies, even if some frequencies are lower than red. A blue shift means a shift to higher frequencies even if some frequencies are higher than blue.
But what about a violetshift? This phrase isn't used, but if it was, it'd mean the same thing as blueshift.
But what about a violetshift? This phrase isn't used, but if it was, it'd mean the same thing as blueshift.
February 25, 2025 at 4:57 PM
A redshift means a shift to lower frequencies, even if some frequencies are lower than red. A blue shift means a shift to higher frequencies even if some frequencies are higher than blue.
But what about a violetshift? This phrase isn't used, but if it was, it'd mean the same thing as blueshift.
But what about a violetshift? This phrase isn't used, but if it was, it'd mean the same thing as blueshift.
Every process that releases energy from a system involves the conversion of mass to the released energy. It's not just nuclear reactions. This fact is fundamental to the way that mass and energy behave. But this fact isn't useful outside of physics 'cause the changes in mass are tiny.
#ITeachPhysics
#ITeachPhysics
February 24, 2025 at 8:23 PM
Every process that releases energy from a system involves the conversion of mass to the released energy. It's not just nuclear reactions. This fact is fundamental to the way that mass and energy behave. But this fact isn't useful outside of physics 'cause the changes in mass are tiny.
#ITeachPhysics
#ITeachPhysics
Human vision uses 20+ visual cues to see depth despite capturing 2D images on the retinas. One of these is the texture gradient cue, shown on the right. I was careful to make it so that no other depth cues are present (except a bit of recess shading). The left image is without this cue present.
February 17, 2025 at 6:15 PM
Human vision uses 20+ visual cues to see depth despite capturing 2D images on the retinas. One of these is the texture gradient cue, shown on the right. I was careful to make it so that no other depth cues are present (except a bit of recess shading). The left image is without this cue present.
Using the Laplace equation, you can solve analytically for the electric field strength near a statically charged conical tip or pit. I've plotted the results here. The field is very strong very close to a very sharp tip. This is why lightning rods are spikes. #ITeachPhysics
February 14, 2025 at 4:55 PM
Using the Laplace equation, you can solve analytically for the electric field strength near a statically charged conical tip or pit. I've plotted the results here. The field is very strong very close to a very sharp tip. This is why lightning rods are spikes. #ITeachPhysics
The spikes you see coming out of stars in telescopic images mostly arise from the diffraction of light as it flows past the support arms that hold the secondary mirror in place. Diffraction is well understood, so which kind of support arms leads to which pattern is predictable. (I made this pic)
February 13, 2025 at 3:56 PM
The spikes you see coming out of stars in telescopic images mostly arise from the diffraction of light as it flows past the support arms that hold the secondary mirror in place. Diffraction is well understood, so which kind of support arms leads to which pattern is predictable. (I made this pic)
Some people get scared away from taking medications because of a long list of potential side effects on the packaging or documents, but *everything* has potential side effects, even drinking water. A risk-benefit analysis done with medical professionals is the best way to decide about taking meds.
February 12, 2025 at 4:54 PM
Some people get scared away from taking medications because of a long list of potential side effects on the packaging or documents, but *everything* has potential side effects, even drinking water. A risk-benefit analysis done with medical professionals is the best way to decide about taking meds.
During evaporation of water, there are water molecules from the air hitting and sticking to the surface and becoming liquid, in addition to water molecules from the liquid shooting off into the air. The evaporation rate therefore depends on the air's relative humidity.
February 11, 2025 at 6:08 PM
During evaporation of water, there are water molecules from the air hitting and sticking to the surface and becoming liquid, in addition to water molecules from the liquid shooting off into the air. The evaporation rate therefore depends on the air's relative humidity.
"Infrared radiation" does not mean the same things as "thermal radiation." Infrared radiation is any radiation with a wavelength between mircowave and visible light, regardless of how it's created, while thermal radiation is any radiation created by thermal emission, regardless of wavelength.
February 10, 2025 at 7:57 PM
"Infrared radiation" does not mean the same things as "thermal radiation." Infrared radiation is any radiation with a wavelength between mircowave and visible light, regardless of how it's created, while thermal radiation is any radiation created by thermal emission, regardless of wavelength.
I made this plot for a class I teach. For small grazing angles, the majority of the incident light is reflected from the flat surface of a non-lossy transparent material. Some students tend to think that transparent materials don't reflect light. The data in this plot is from the Fresnel equations.
February 6, 2025 at 8:11 PM
I made this plot for a class I teach. For small grazing angles, the majority of the incident light is reflected from the flat surface of a non-lossy transparent material. Some students tend to think that transparent materials don't reflect light. The data in this plot is from the Fresnel equations.