Worth a Look Archive - Page 4
3C273 Activity: Faster Than a Speeding Bullet... - Feb 1, 2011
How fast is that jet in the image above moving away from the quasar? You can calculate the velocity yourself in 3C273 Activity: Faster Than a Speeding Bullet... from Chandra. You'll find that it's moving impossibly fast--faster than the speed of light. The activity explains how this appears to be true. If you want to learn more about the calculations astronomers use for large distances, be sure to check out the other activities on 3C273, too.
Physics in Action: Sonic Shock - Dec 1, 2010
For more on shockwaves, and how engineers have insulated space vehicles from the shockwave's heat, visit Physics in Action: Sonic Shock.
Lasers can help astronomers bring stars into focus. A laser, tuned to a sodium spectral line, shines backward through the telescope, and this laser light excites sodium atoms located in a thin layer of the atmosphere, producing in effect an artificial star. Astronomers can then see how the atmosphere distorts the laser star and then compensate to clarify their images. This relatively new technique means ground-based telescopes can be just as useful as those in Earth orbit. See First Supernova Discovered with Laser Guide Star Adaptive Optics and Rubber Mirrors and Artificial Stars for a fuller explanation.
20 Ways the World Could End - Oct 16, 2010
There are many ways to destroy the Earth besides a meteorite impact. For a fun look at a few of these, see Discover Magazine's "20 Ways the World Could End." (Notably, an asteroid impact is number one on the list.)
An MIT group has figured out how to split water molecules to produce hydrogen and oxygen gas, in a tabletop experiment using inexpensive materials. The energy to run the reaction comes from electricity. The goal, though, is to power the experiment by sunlight--very similar to photosynthesis, except that the products are oxygen and hydrogen gas instead of sugar.
PhysicsCentral: Do You See What Eye See? - Sep 16, 2010
Laser surgery of the eye, more popularly known as LASIK, is an important use of lasers in medicine. See PhysicsCentral: Do You See What Eye See? to learn how it's done.
Four Color Theorem Intro - Sep 1, 2010
Physicists determine air gives liquids their splash - Aug 16, 2010
What happens when a droplet of liquid lands on a solid surface? What determines the way it splashes? How does what happens depends on the kind of gas and the pressure?
Tsunami - Aug 1, 2010
Remember the 2004 Sumatra tsunami? Take a look at this Wikipedia photo.
soapbubbledk - Jul 16, 2010
Visit the colorful and well-illustrated soapbubbledk to learn about soap bubbles and films.