Optics basics: vector fields

In my regular discussions of optics and electromagnetic fields in general, I use a lot of pictures with arrows on them.  For instance, my post on Faraday’s law has the curious figure,

where the red arrows represent the “electric field” and the blue arrows represent the “magnetic field”.  As another example, I’ve illustrated an electromagnetic wave numerous times by the following collection of arrows,

where the red arrows are again the electric field and the blue arrows are the magnetic field (we won’t concern ourselves with the difference between B and H for now).

As a longtime physicist, it is easy to forget that the meaning of these arrows is not necessarily obvious to an outsider.  The individual arrows are referred to as vectors; the collection of a group of these vectors over a region of space is known as a vector field.  The word “field” is appropriately descriptive: just as a “corn field” is a collection of corn arranged throughout a region of land, a “vector field” is a collection of vectors arranged throughout a region of space.

I’ve tried to explain the meaning of vector fields in individual posts when they have appeared; but it was time to put all these ideas in one place.  In this article we will address the concept of a vector field, and explain what such fields mean for electricity, magnetism, and light waves.

Continue reading

Posted in Optics basics, Physics | 4 Comments

Weird science facts — a full year of facts edition!!!!!

This past Sunday, I officially reached my goal of doing a full year’s worth of #weirdscifacts on Twitter — 365 days in a row of posting weird science!!!!!!!!!

I will probably wind down my facts sometime in the future — despite prodding from the Twitter community, I’m not sure I have the energy (or the facts) to fill another full year.  Nevertheless, I’ll keep doing them as long as I can keep finding facts and keep myself entertained.

Something else I’ve been mulling over: would it be worth it to try and make the collection of #weirdscifacts into a book and/or a daily calendar?  I’d be interested to hear what folks have to say!

Without further ado, here are the past week’s facts:

360. Mar 08: When G. Washington died in 1799, a doctor offered to resurrect him via blood transfusion! This fact comes via @history_geek‘s excellent book “Blood Work”, which I am currently reading.  Washington likely died in part due to the “treatments” of his doctors.  The suggested resurrection, done via a transfusion of animal blood, was declined by the family.

361. Mar 09: The sad case of the radium girls: death by painting watch dials. In an era of deregulation and corporate negligence, this story seems especially timely.  The radium girls case led to great advances in the rights of workers to sue their employers for occupational diseases.

362. Mar 10: Milburn Model 27L electric car, top speed 23 mph, range 90 miles.  Made in 1923. These are impressive statistics for an electric car that was made nearly 90 years ago!  I encountered the Milburn at the Museum of Science and Industry in Chicago; photo and description.

363. Mar 11: Japan’s quake shortened length of day by 1.26 microseconds. A figure skater (like myself) can change the speed of a spin by pulling one’s arms in and out.  The earthquake in Japan shifted the distribution of mass on the spinning Earth, changing its spin rate much like a figure skater does.

364. Mar 12: For all the destruction of the Japanese tsunami, it is relatively small compared to others in history.

365. Mar 13: number 365!!!!!! In terms of cell count, humans are 90% microbial and 10% human! (h/t @kwinkunks)

366. Mar 14: Happy #weirdscifacts Pi day! In 2005, Lu Chao successfully recited 67,890 digits of Pi from memory in 24 hours. Chao planned to recite 90,000 digits, but slipped up at the 67k mark.  I find this astonishing because I can’t remember a 16-digit credit card number.  It took Chao 24 hours to finish reciting.

367. Mar 15: The Megatherium Club (1857-1866), and the shenanigans that got them booted from the Smithsonian castle. Quoting Wikipedia, “They spent their weekdays in the rigorous and exacting work of describing and classifying species. But their nights were spent in revelry.”

Posted in Weirdscifacts | 6 Comments

The Giant’s Shoulders #33 is up!

Today’s the day to read your monthly compilation of history of science posts — The Giant’s Shoulders #33 is out at The Renaissance Mathematicus!  ThonyC was busy, so Sascha the canine philosopher filled in to give us an excellent carnival through the eyes of a dog!

The next edition will be back under human control — Jai Virdi at From the Hands of Quacks will host the April carnival.  Entries should be submitted by the 15th of the month to the Blog Carnival website or directly to the host blog.

 

Posted in General science, Science news | 1 Comment

Weird science facts, March 2 — March 8

In less than a week, I’ll have done a #weirdscifacts a day for a full year!!!!!!!!!!!!!!

Here are the past week’s facts:

354. Mar 02: Physics Nobelist Shockley was troubled, and once attempted suicide with solo game of Russian roulette.

355. Mar 03: The gin-and-tonic laser! We’ve noted in previous facts that physicists like to do interesting things with booze — Glaser’s experiments with bubble chambers using beer, for instance.  Post by @oliviakoski!

356. Mar 04: Curse of the cubic! Lots of mathematicians who worked on polynomial equations met bad ends.

357. Mar 05: In 1919, radium was world’s most expensive substance at $3 million/ounce. The Curies, who discovered radium, took years and processed tons of raw ore to get a tenth of a gram of the substance.  It discuss the history briefly in this old post; with this in mind, it is not surprising that the substance ended up being so expensive! (via yesterday’s “Final Jeopardy”; I got it right!)

358. Mar 06: Have I mentioned yet that Brian May of “Queen” has a Ph.D in astrophysics? May was studying astrophysics before the band took off; in recent years, he went back to school and finished his degree!

359. Mar 07: Chemist Carl Scheele (1742-1786) likely died from his extensive exposure and taste testing of chemicals, including cyanide! Nobody is certain what exactly caused his death, but it was almost certainly due to experimentation.  He apparently was also aware of the risks, referring to his poor health as “the trouble of all apothecaries”.

360. Mar 08: When George Washington died in 1799, a doctor offered to resurrect him via blood transfusion! (via @history_geek’s newly-released book “Blood Work“!)

Posted in Weirdscifacts | 8 Comments

6 days until the deadline for The Giant’s Shoulders #33!

This is the monthly reminder that the deadline for The Giant’s Shoulders, the monthly history of science blog carnival, is only six days away! The Giants’ Shoulders #33 will be hosted by Sascha the canine philosopher at The Renaissance Mathematicus. Submissions as usual either direct on the host c/o Thony C. or at the Blog Carnival website by 15th March at the latest.

As an important aside, we still desperately need more hosts for upcoming editions of the carnival!  If you’re a historian of science of just a blogger with an interest in the history of science, please consider volunteering for an upcoming month!

Posted in General science, Science news | Leave a comment

Cats, cats, cats!

I’m struggling to get a new optics post going for the blog; I’ve got a number of possibilities I’m exploring, but it will likely take a few days to get it going.  In the meantime, I realized I haven’t done a catblogging post for a long, long time!  Now seems like a great time to share some pictures that I’ve had around for a while of the kitties!

Continue reading

Posted in Animals, Personal | 17 Comments

Peter Straub’s Ghost Story

I have historically had a curious quirk about my fiction reading that I suspect a lot of people share: the more famous a work is, the less motivated I am to read it.  This may be the hipster within me acting out, but fortunately in more recent years I’ve combated this tendency and have caught up on a number of books I should have read a long time ago.

Among my recent victories was finally reading Peter Straub’s Ghost Story (1979):

Straub’s book was a bestseller upon its release, a watershed in Straub’s career, and even resulted in a 1981 movie (more on this in a moment).  There probably isn’t much I can say about this monumental work that hasn’t already been said a zillion times on the internet before, but it’s my blog and I’m going to share my thoughts on it anyway!

Continue reading

Posted in Horror | 8 Comments

A short promotional post: Math Methods is available on Amazon!

At the risk of turning this blog into a series of shameless self-promotions (perhaps it is already too late), I should note that my textbook is now available on amazon.com!

I wasn’t paying close attention, because Amazon originally showed it as being released at the end of February, but it seems it got released in the middle of the month instead.

In what seems to be good news: even though it’s only been on the market for a short time, as of this writing Amazon has only one copy left in stock!  The book is either selling well or they didn’t bother to stock any copies!  (Also, how is it that there are already 2 “used” copies being sold — at $20 higher cost than a “new” one?)

P.S.  For instructors out there who might be considering using the book in a class: there will be a solutions manual, which I am currently trying to finish!  It’s taking some time to compile the solutions from old homeworks that I’ve used in class.  Hopefully within the next month I’ll have the manual available through the Cambridge site.

Posted in Optics, Personal | 6 Comments

My interview on Peer Review Radio!

Those who follow me on Twitter have already heard this, but for those who haven’t: I was interviewed by Adrian Ebsary for an episode of Peer Review Radio that was broadcast on Tuesday!

The episode is titled, “Go sing it on the mountain — communicating science online”, and I pontificate in it on the history of science, open science, and of course online science communication.  I’m in great company, as the other interviewees are Bora Zivkovic, Chris Gunter, and Marie-Claire Shanahan.

Give it a listen if you have a chance, and let me know what you think!  To be honest, I haven’t listened to the finished episode myself yet — I’m afraid to find out what I sound like!  (I’ll be listening over the next couple of days.)

It was my first official radio interview, and it was a lot of fun! Thanks to Adrian for inviting me!

Posted in General science, History of science, Personal | 8 Comments

Weird science facts, February 23 — March 1

I’m getting tantalizingly close to having posted a full 365 days of #weirdscifacts on Twitter!  Here are the past week’s facts:

347. Feb 23: Paleontologist C.D. Walcott (1850-1927) was inspired to study Cambrian strata when his wagon hit & split open a sandstone fossil rock. Lots of scientists have had their careers dictated by odd chance: we’ve mentioned previously physics Nobel prize winner Chadwick, who intended to study math but accidentally sat in on the physics entrance exam!  Walcott’s career was literally determined by a bump in the road.  (Source for #weirdscifacts [pdf, p. 5])

348. Feb 24: Largest recorded beaver dam: 2790 ft long, in Northern Alberta, Canada. That is, for the record, over nine football fields in length!  It was obviously made by multiple families of beavers working together.

349. Feb 25: In 1929, Werner Forssmann put a catheter into his own heart, tying up a nurse who tried to stop him! With the catheter in place, he then walked himself up to the X-ray room to take an image and prove that he had accomplished his goal.  (h/t for last #weirdscifacts to @JenLucPiquant and @io9, and this article)

350. Feb 26: Getting X-rays from scotch tape! I wrote a blog post on the subject some time ago.  When tape is peeled, electric charges are separated between the peeled and unpeeled portions.  In a vacuum, the electrons can “jump” back across the gap, and release X-rays upon deceleration.  Don’t worry — under ordinary circumstances (ordinary atmospheric pressure), there are no X-rays released.

351. Feb 27: The cousin of the Schrodinger’s cat thought experiment: quantum suicide!

352. Feb 28: The Campbell-Stokes sunshine recorder — invented in 1853 and still used today. With a wooden bowl and a glass sphere, you too can record the intensity of sunlight over the course of the day! (h/t @patrickneville)

353. Mar 01: “Cactus Walking On 20 Legs Found In China“. This ancient creature was a type of spindly worm, and is only known through the fossil record.  Did it actually “walk”?  We don’t know for sure.  Nevertheless, it is a very weird creature. (Post by @rkrulwich)

Posted in Weirdscifacts | 3 Comments