The Twitter #weirdscifacts from May 23 – June 05 are below the fold!
Archive for the '[PhysicalScience]' category
This post is a repost of some proto-blogging I did on my department web page when I was a post-doc in Amsterdam. The web page is gone, now, so I thought I'd revise the essay significantly for the blog here.
I don't think it is too much of an unfair generalization to say that science and scientists are rather unappreciated in the United States. Folks are quite happy to reap the benefits of science and technology when it comes to their computers, iPhones, etc., but can be dismissive or indignant to scientists when their results show people truths that they are uncomfortable with, e.g. evolution and global warming.
That's not to say that other countries are necessarily much better, but I do occasionally run across pro-science efforts elsewhere that surprise me. From 2003-2004, I did my post-doctoral work at the Vrije Universiteit in Amsterdam, The Netherlands, an experience that I will count as one of the best times of my life. Amsterdam is just a wonderfully livable, walkable city, and even on my limited salary I was able to enjoy it immensely. While there, I kept up my figure skating training at the Jaap Eden Ijsbanen, which is located in the neighborhood of Watergraafsmeer outside of the city center. I would take the bus to the rink from my apartment, and every day would travel down Maxwellstraat and past Lorentzlaan, but it didn't occur to me until near the end of my time in The Netherlands that these streets are named after the physicists James Clerk Maxwell and Hendrik Antoon Lorentz!
In fact, all streets in the neighborhood of Watergraafsmeer are named after famous scientists and mathematicians, which is really a joy for a physicist like me. So after skating at the last day of the season at the Jaap Eden Ijsbanen, I decided to wander the neighborhood and hunt down the streets of those physicists whose work in the optical sciences has been a great influence on my own life's work, combining physics & travel blogging!
I present the streets in no particular order of chronology or significance; rather I present them in the order that I wandered past them. Information about the scientists themselves I gleaned from a variety of sources, including printed biographies, internet sites, and historical articles by my thesis advisor. Pictures of the various scientists were taken from Wikipedia. So without further ado, let us begin our tour -- feel free to follow along the trail via Google maps...
In my blogging on the history of science, I tend to focus on the details of classic experiments -- the how, why, and what of scientific history -- and don't dwell as much on "who" actually does the work. The personalities that drive the research, however, say as much about how science gets done as the actual techniques, and I've been trying to deepen my understanding by learning a bit more about the famous figures of science.
To this end, I've started reading a number of biographies of famous physicists. Until I started looking, I was unaware that many of these biographies existed! The first on my list was Alan Hirshfeld's biography of my favorite scientist of all time, Michael Faraday*, titled The Electric Life of Michael Faraday (2006):
I thought I'd share a few impressions about the book, and about Faraday in general!
This post is for the special "fools, failures and frauds" edition of The Giant's Shoulders.
The early 20th century was clearly an exciting time to be a physicist. In 1905, Einstein published his special theory of relativity, radically revising human concepts of space and time. In the same year, and the same issue of the Annalen der Physik, Einstein really sparked the "quantum revolution" with his explanation of the photoelectric effect, an explanation that would scramble existing preconceptions of the nature of light and matter and would eventually shake the deterministic foundations of physical theory.
By the teen years of the 1900s, it must have seemed to many physicists that no idea was too crazy to possibly be true! Furthermore, the simplicity and elegance of Einstein's relativity must have suggested to scientists that the secrets of the universe remaining to be discovered would be of the same sort of "beautifully obvious" form.
One researcher who was seduced by this sort of thinking was Richard C. Tolman. In 1914, he published a paper on a new physical principle that he referred to as "the principle of similitude". In Tolman's own words, his principle represented a new form of "relativity of size", which "provides a very simple and general method for obtaining conclusions as to the form of functional relations connecting physical magnitudes."
Tolman's theory was bold, it was powerful... and it didn't really work out. It is a great example of a failed theory, and even more fascinating because its proponent was no crackpot, and its insights turned out to have some practical use in the end. There's even a whiff of a conspiracy surrounding similitude, which I will describe at the end of the post!
This post is closely related to the idea of dimensions in physics; if you're not familiar with this concept, check my earlier post here.
(I've been doing a daily "weird science fact" on Twitter, with the goal of doing a full 365 days of facts. The problem is that Twitter doesn't allow one to search further back than 1 week! I'm going to keep a weekly log of the weird facts of the week on the blog, but will do 2 weeks at a time until I catch up.)
The Twitter #weirdscifacts from March 28 - April 10 are below the fold!
One of my goals in blogging has been to run a series of posts covering the "basics" of optics, namely those concepts that form the basis of an understanding of the more advanced topics investigated by researchers today. Though I've done a pretty good job so far, I recently realized that I've left out a discussion of the most important tool of the optical scientist, and one of the most important technological advances of the modern era: the laser!
Image via Wikipedia, of an experiment at the Air Force Research Lab.
"Laser" is an acronym for "Light Amplification by Stimulated Emission of Radiation", and it refers to a device that produces light by an unusual physical process not typically found in nature.
In fact, 2010 marks the 50th anniversary of the laser, as the first functioning device was built in 1960 by Theodore H. Maiman at Hughes Research Laboratories in California. To draw attention to this anniversary, optics organizations have instituted a yearlong celebration called LaserFest, and many special events are planned and have already taken place; my favorite being the Lasers Rock! concert that was held in May at the CLEO/QELS conference:
Musical group "Second and Third Harmonic Generation" playing at Lasers Rock! Picture via Ksenia's CLEO/QELS blog.
I hardly need to describe the impact lasers have had on our society, and it is hardly possible to list all of the applications! Among other things, lasers are used to read CDs, DVDs and Blu-ray discs, they form the basis of the fiber-optic communications systems by which you are probably reading this post, they are used in medicine both to diagnose problems as well as to perform laser surgery, they are used to cut material in industrial fabrication. Their properties make them ideal for doing optics research of all sorts, and they are now an essential tool for researchers.
In this post I would like to describe the physics of lasers. This is no mean feat, because there is a lot to say about how they work, and many variations on the fundamental idea that was first proposed by Charles Townes in the 1950s¹. I will proceed somewhat carefully:
- First, I will discuss what a laser is, and what properties a laser has that distinguishes it from "ordinary" light sources like light bulbs.
- Second, I will describe the fundamental physics behind the lasing effect, in particular the process of stimulated emission.
- Finally, I will explain the engineering that is used to take advantage of stimulated emission and make a laser.
Let's take a look...