An intriguing discussion is arising across some physics blogs about the role of philosophy in physics. As Lubos Motl points out (and, before him, Steven Weinberg), the two fields share a common ancestry in a deep desire to understand the fundamental nature of reality beyond our everyday experience, but today the insights of philosophy have very little impact on the actual practice of physics.

At the core of this discussion is a quote by science philosopher Paul Feerabend (from For and Against Method, dug up by Steve Hsu, which focuses on the "savage" nature of the mid-twentieth century theoretical physics who, as opposed to their predecessors Einstein, Bohr, and the rest, didn't particularly care about philosophical concerns.

Sean Carroll over at Cosmic Variance points out that this might also be related of the shift of physics' intellectual center from Europe (which has always had a broader intellectual tradition, and a deeper interest in philosophy) to America (where specialization is more the norm).

I'm more European in outlook. I attended a liberal arts college where I majored in physics and minored in philosophy (along with mathematics), so I tend to be fairly sympathetic to the old school physicists, who sought to understand nature instead of just predicting the results of experiments. Still, the point can't be avoided - physics without philosophy has been wildly successful.

It's unclear that the addition of philosophy would benefit physics in any practical way. The real progress in quantum physics came about only when the philosophy - the bickering between Einstein, Bohr, and others - was swept under the rug. Don't get me wrong - the bickering was immensely fascinating and entertaining, but it proved to be a distraction which never really resolved anything. Today, the philosophical questions about quantum physics (which were originally the core question of the theory) are ignored and dismissed by physicists.

Of course, there are those on the periphery of physics who feel that the philosophical insights are the ones that need added back into the field, but they are by far the minority. They point out that the great revolutions of physics were performed by men who were deeply philosophical - Newton, Faraday, Einstein, Boltzmann, and Bohr come to mind. Today, we may need such a revolution to advance physics and some claim that this must go hand-in-hand with a philosophical resurgence.

While there may be some merit to this line of reasoning, until their philosophical insights can join back with physical insights to provide a solid prediction, I'm afraid that philosophy and physics will probably remain divorced disciplines.

While the Large Hadron Collider (LHC) continues to get the majority of buzz in particle physics news stories (anticipated to start back up in October or so), new research being done in the BELLA (BErkeley Lab LAser) program at the Lawrence Berkeley National Laboratory may show such large-scale particle accelerators to be obsolete ... or at least cost prohibitive. (Austria announced plans to drop out of CERN involvement, but then changed their mind, bringing up concerns that other nations might start looking to CERN and LHC funding as an optional expense that could be trimmed or re-allocated in their budget debates.)

The new particle accelerators are being designed and tested as part of the BELLA program, which use a series of lasers to accelerate particles over a span of inches, rather than the miles needed in traditional particle accelerators. Though the "big boy" particle accelerators are still much more powerful, using the BELLA-style accelerators in serial (one after the other) could get particles going nearly as fast in a much shorter period of time, allowing for some similar tests to be run in a much smaller facility.

Other proposals have been made in the past, such as desktop plasma-based accelerators. It remains to be seen which of these proposals will prove most viable.

A while back, Stephen Hawking and his daughter, Lucy, released a children's book that teaches scientific concepts to young readers: George's Secret Key to the Universe. The book covers concepts mostly from astrophysics, especially focusing on black holes, Hawking's area of expertise. There's an entire "mini-book" in one chapter that is nothing short of a textbook for children on the basic information about black holes and, throughout the entire book, there are interesting call-outs and sidebars with scientific information, as well as several colorful pages of photographs from outer space. Read our full review of the book now. (Review of the sequel should be coming in the next few weeks.)

Physicists have just created a variation of a black hole which, instead of trapping photons (particles of light), traps phonons (particles of sound). Yes, waves of sound vibrations in matter (like waves of light in space) can be expressed as either waves or particles in quantum physics, a principle known as wave particle duality.

This strange black hole phenomenon is achieved within the curious form of matter known as a Bose-Einstein condensate. In this rare state of matter, the flow of sound through the material is expressed the same way that the movement of light in a gravitational field is expressed, which has led the scientists to realize that they could create this analog of a black hole for sound. Multiple groups were working to achieve this, but the success seems to have come from Oren Lahav, Jeff Steinhauer, and colleagues at the Israel Institute of Technology, in Haifa.

Sound waves created within the "black hole" (which, I think, would more appropriately be called a "black noise hole" or maybe a "quiet hole," but neither have a catchy ring to them) are unable to escape, because when they attempt to reach the event horizon, they can't pass that barrier because they are pulled in at supersonic speeds. In other words, they are pulled into the black hole faster than they can travel out, like someone trying to swim against rapids or a waterfall.

But things get stranger ... because it's possible that these black holes for sound will also exhibit Hawking radiation. Quantum physics indicates that pairs of "virtual phonons" are constantly being created and destroyed. If one of these pairs forms near the event horizon of the sound black hole, one of the phonons may end up getting pulled into the black hole while the other escapes. This means that the sound black hole could emit phonons, which is exactly what one expects for light instead of sound in regular black holes.

With the successful creation of a black hole for sound, it appears that the race is on to detect Hawking radiation for sound.

Related Articles:

• New Scientist - Physicists create 'black hole for sounds'
• Technology Review - Acoustic Black Hole Created in Bose-Einstein Condensate
• Physicsworld.com - Black-hole analogue traps sound
• ArXiv.org - A sonic black hole in a density-inverted Bose-Einstein condensate
• What Is a Black Hole?
• What Is Hawking Radiation?
• Useful definitions: Event Horizon, Phonon, and Bose-Einstein Condensate