Free Republic

Sound has negative mass, and all around you it's drifting up, up and away — albeit very slowly. That's the conclusion of a paper submitted on July 23 to the preprint journal arXiv, and it shatters the conventional understanding that researchers have long had of sound waves: as massless ripples that zip through matter, giving molecules a shove but ultimately balancing any forward or upward motion with an equal and opposite downward motion. That's a straightforward model that will explain the behavior of sound in most circumstances, but it's not quite true, the new paper argues. A phonon — a...

How did a giant, gaping hole tear through the massive Oroville Dam’s main concrete spillway last week, setting in motion the chain of events that could have led to one of America’s deadliest dam failures? Dam experts around the country are focusing on a leading suspect: Tiny bubbles.The prospect is simple, yet terrifying and has been the culprit in a number of near disasters at dams across the globe since engineers discovered it about 50 years ago. In a process called “cavitation,” ...

Beware the bubble’s burst Increased knowledge about cavitation highlights the destructive power of fast-flowing water by David Catchpoole Published: 24 October 2007(GMT+10) This is the pre-publication version which was subsequently revised to appear in Creation 31(2):50–51. When Britain’s Royal Navy ships were suffering considerable and unexplained damage to their ships’ propellers in WWI, physicists worked out that violent ‘bubble cavitation’1 was the cause. This happens because tiny bubbles grow and then collapse as a result of pressure variations in the turbulent water around a propeller. But nobody knew just how hot the bubbles could get before releasing their destructive energy....

The U.S. Navy certainly doesn't seem to have any shortage of unconventional weapons in development, but it looks like it still has plenty more ideas on its plate, with a recent patent revealing yet another new weapon that takes a slightly different path towards its target. While this one is unconventional, it certainly doesn't appear to be non-lethal, employing sonar to generate what the Navy describes as "acoustic remote cavitation," which can supposedly destroy torpedoes, mines, and any other "undesirable objects" in its path. What's more, the Navy says that can be done from a distance of up to one...