Appearing

Joan and I will be busy with 13 appearances in the Los Angeles area in the next 3 weeks. For those who would like to attend, but live too far away, the talks will be available on DVD.

The events listed below are open to the public with little or no charge, except as noted:

1)  Monday, March 14, 7:45pm

     Los Angeles Astronomical Society at the Griffith Observatory

2)  Thursday, March 17, 11:30 am
     Westlake Village Republican Women Federated (WVRWF)
     Westlake Inn in Westlake Village
     Admission $30/person for lunch. Email me by 3/15 for reservation.

3)  Thursday, March 17, 7pm

     South Bay Amateur Radio Club

     Torrance Medical Center, 3330 Lomita Blvd., Torrance

4)  Friday, March 18, 7:15pm

     Ventura County Astronomical Society

     Mesa Union school, 3901 North Mesa School Road, Somis

5)  Saturday, March 19, 7:30pm

     Riverside Astronomical Society

     Cossentine Hall, La Sierra University, 4700 Pierce St.

6)  Monday, March 21, 8pm

     B’nai B‘rith at Temple Adat Elohim, 2420 E. Hillcrest Drive, Thousand Oaks

7)  Sunday, March 27, 5:30pm

     STARS fundraiser for neurological diseases

     Admission is $75/person for dinner and donation.

     Call Sharon at 310.471.1024 for reservation.

Disappearing

Ever dream you could leave all your worries behind and just disappear? Wouldn’t it be great if someone made a real cloaking device like the Romulans in Star Trek?

Well, one day these fantasies may come true—or at least, partially so. Scientists around the world are working to develop cloaking devices, and they are making some progress.

Cloaking devices are part of a larger field—stealth technologies, all of which strive to make an object “invisible” by making it “look” like its surroundings. Every way we “look” at things involves sensing electromagnetic (EM) waves—visible light, infrared, radar, etc. Thus, we “see” objects only if they emit or reflect EM waves differently than their surroundings.

The simplest stealth technology is passive camouflage: having a fixed color or pattern that matches the environment. Active camouflage is being able to dynamically change one’s appearance to match a changing environment, and one of its greatest masters is the flounder.

The first image, by “Moondigger”, shows a flounder blending with pebbles on the sea floor.

The second image is even more spectacular; a flounder placed over a checkerboard at Chicago’s Field Museum mimics the pattern of black and white squares.

Most people know about the very successful stealth aircraft flown by the U.S. Air Force in Desert Storm. Since the sky does not reflect radar and conventional aircraft do, a plane designed to not reflect radar looks like empty sky—it’s invisible to radar. But this highlights a limitation of most stealth technologies. A stealth plane is invisible to radar reflecting backward, but can be detected by side-scattered radar waves and can be seen with visible light. These planes are partially invisible.

Most of us don’t worry about being detected by radar (unless we’re driving too fast); we are more interested in being unseen in visible light. How’s that coming?

Well, visible light cloaking devices are not available at Costco yet. Scientists have made cloaks from metamaterials, but these are affordable only for hiding microscopic objects, and then only at certain wavelengths of light and only if one looks head-on. The basic idea is to bend light around the object, such that an observer sees the same light whether the cloaked object is there or not. Again, the object is invisible only at certain wavelengths and from certain directions. A schematic, by V. Shalaev of Purdue, is shown below.

The latest and best results, published this January and February, use calcite crystals as prisms to cloak objects up to 2mm across, about the size of a small ant.

It may be many years before we can use cloaking to make those extra holiday pounds disappear.

Best Regards,

Robert

Dr. Robert Piccioni

www.guidetothecosmos.com
Author of "Everyone's Guide to Atoms, Einstein, and the Universe"
and "Can Life Be Merely An Accident?"