The Los Alamos National Laboratory has a paper explainin how to measure light speed using the ping command included with most operating systems. It’s very interesting.

An additional explaining: light speed is constant (c=3e8, aprox.), but propagation speed is not constant. It depends on the medium (being exact, it depends on the propagation constant, ß, of the medium) and can be calculated using one of the following equations:

vp=1/sqrt(μ*ε), where μ and ε are constant parameters that depend on the medium.


vp=2*pi*f/ß, where ß is the propagation constant of the medium.

For optical mediums a simpler expression is given using material’s effective refraction index (), but I cannot remember the expression now O:-)

Crees en OVNIs y extraterrestres? en Dios? en la Creacin? aceptas los “dogmas” presentados por pseudocientficos? Si la respuesta a todas estas preguntas es NO, quiz te interese darte una vuelta por ARP-SAPC (Alternativa Racional a las Pseudociencias – Sociedad Para el Avance del Pensamiento Crtico).

Yo ya me he apuntado a su lista de correo y leo su boletn, a qu esperas t?


This guy should have lotta free time and also lotta money. He’s putting various things into the microwave and watching what happens.

By the way, I have the correct answer to most of the experiments he did: the microwave (really, the magnetron) broke. Of course, those (failed) experiments do not appear in the web page.

Have you ever seen an hologram? No? Now you can see them and also make them.

Here’s an AOL guy who has managed to mount an hologram-generator system from a PIN diode. You can see some photos (2D, of course)

There are some other sites talking ’bout holography: drawn by hand, creating different types of holograms, The Holography Book, Google’s directory and Holoworld (by the creator of diode’s holography).

Of course, you can also look at Slashdot‘s discussion on this topic.

Ten years ago, when people get bored, they masturbated frenetically until they went to sleep. Today, people does strange (and sometimes useful) things.
This is one of the most incredible utilities for a Pringles tin: making an antenna. You can read the article in O’Reillynet and see a photo here.

Get a lot of info about antennas in the Antennas WebSite of the Technical University of Valencia (information is in Spanish and in English).

If you have a CRT monitor (the most usual ones people with desktop computers have), you can broadcast your voice or simply favourite music. How? With Tempest for Eliza. The program moves the cathodic ray tube [CRT] of you monitor, and the interferences fall in the AM band. Incredible. Read comments at Slashdot.
Update: you can also use your motherboad to broadcast in the FM band… read Slashdot’s story or visit author’s page (web page seems not to work, Google seems not to have it in cache).
Another update: this page is full of info about Tempest: