About Physics

Whatever Happened to the Philosopher Physicist?

2009-07-08T00:08:33Z

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.

Smaller Particle Accelerators

2009-07-02T12:19:53Z

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.

Review of Stephen Hawking's Children's Novel

2009-06-24T07:37:05Z

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.)

Black Hole For ... Sound?

2009-06-21T10:25:27Z

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

Robotics Programs Offer Missing Element to Science Education

2009-06-19T23:45:16Z

Earlier this month, there was a great blog post over at Physicsworld.com, "The power of robotics," in which Robert P. Crease (philosophy professor at Stony Brook University) discusses his son's participation in the FIRST (For Inspiration and Recognition of Science and Technology), a major robotics competition charity founded by inventor Dean Kamen. The article discusses not only his son's personal experiences, but also the fact that the hands-on element of the robotics design is a crucial component of science education which is being largely ignored by our national science curriculum.

I previously discussed the benefits of FIRST back in April, around the time of their national competition in Atlanta, Georgia.

For more about actually creating robots, check out the "Robotics and Robots" section of About.com Inventors...

Time Travel as a Means of Hacking Computers

2009-06-19T23:26:21Z

In physics, time travel is technically allowed by the theory of relativity. The results that demonstrate time travel are called closed timelike curves (or CTC), which are paths that begin and end at the same coordinates in spacetime.

Though technically allowed, the closed timelike curves in relativity do create all sorts of problems for physics, because the initial conditions are no longer static. All predictivity seems to be lost. David Deutsch was able to describe a way to avoid this in 1991, by explaining how the particles begin traveling in a loop that causes them to interact in the initial conditions in exactly the same way they "originally" did, creating sort of a "Groundhog Day" effect.

According to a new paper in Physics Review Letters, it looks like there's a new addition to the problems caused by closed timelike curves: they can be used to break potential quantum encryption techniques. These systems involve using a quantum-mechanical system to encrypt information in a computer system. Here's how the Physics Review Focus newsletter describes the new findings:

Todd Brun of the University of Southern California in Los Angeles and his colleagues have now found a way to use states defined by the Deutsch formulation to decode quantum-encrypted messages. Such a message could be sent as a series of particles, each in quantum state "zero," quantum state "one," or a combination state called a superposition. The intended recipient measures each particle but needs additional information after-the-fact from the sender to distinguish the superpositions from the non-superpositions. But a spy who could distinguish "on the fly" between, say, a zero and a superposition state could intercept the message and also send particles to the recipient that mimic the originals, thereby avoiding detection.
For the spy to accomplish this, the researchers imagine a particle entering a CTC so that it travels around and back in time, allowing it to interact with its future self, so to speak, before going on its way again. They describe an interaction that, in the simplest example, leaves a particle in the zero state unchanged but transforms a superposition of zero and one into a pure one state. A standard measurement by the spy that distinguishes one from zero can then reveal with complete certainty whether the initial state was zero or a superposition.
Ordinarily such a transformation wouldn't be possible without advanced knowledge of the incoming state. The trick, Brun explains, is that the particle interacts with the transformed version of itself that comes back from the future. Brun says the scheme doesn�t violate any laws of physics, but he admits that the logic is hard to grasp. Compared with regular chronological reasoning, he says, "it's definitely cheating."

Related Articles:

Physical Review Focus - Time Travel Beats Quantum Mechanics
Physics Review Letters - Localized Closed Timelike Curves Can Perfectly Distinguish Quantum States by Todd A. Brun, Jim Harrington, and Mark M. Wilde
Physics Review D - Quantum mechanics near closed timelike lines by David Deutsch
What are Quantum Computers?

Warp Drive - A Nice Idea While It Lasted?

2009-06-15T00:40:03Z

A few weeks ago, I mentioned a new warp drive possibility based on string theory, a variant of the Alcubierre drive. A new set of calculations performed by a team of Italian scientists, however, have proposed that a warp drive engine would eventually fail. The massive energy required to manipulate spacetime in the correct way would, according to their calculations, result in a rupture in the fabric of the universe when the massive energy running the drive runs out. This rupture could result in either an explosion or a black hole that might swallow up nearby planets, but it's unclear from the paper which result is more likely ... that depends on certain fundamental properties of our universe which are still being explored by theoretical physicists.

Top Laws of Physics?

2009-06-10T14:46:06Z

Over at the Scienceray blog, they've posted The Top Five Laws of Physics That Have So Impacted Humanity:

Principle of Mass-Energy Equivalence - E = mc² (see our article on special relativity)
Wave Particle Duality of Matter
Electromagnetic Induction: Faraday's Law
Newton's Law of Universal Gravitation and Three Laws of Motion
Maxwell's Equations (see our article on the electromagnetic spectrum)

I'm not necessarily agreeing with this list of the most influential laws of physics ... but I also can't really argue with the idea that they are profoundly significant to our modern science and technology. And, frankly, I can't come up with a much better list (if I'm limited to only 5). The only real beef I have is to point out that Maxwell's Equations include among them Faraday's law of induction, but this isn't a major point: even without Maxwell's work in (mostly) completing electromagnetic theory, Faraday's realization of induction would have been influential on its own.

What do you think of their list? Are these the physical laws that have had the greatest impact on humanity? Leave a comment with what physics concept you think has been most influential.

Related Articles:

World Science Festival 2009

2009-06-08T22:19:40Z

This week New York City is home to the World Science Festival, a celebration of scientific achievement throughout the city. There are some spectacular events planned for this week, starting on Wednesday, June 10, and ending on Sunday, June 14, culminating in the World Science Festival Street Fair at Washington Square Park.

Are you attending the World Science Festival? What events are you especially looking forward to? What events do you wish you could attend?

Thinking About Quantum Mysticism

2009-06-08T20:33:52Z

In the early years of quantum physics, there was a heated debate over the role of consciousness. Many aspects of quantum physics appear, at least with certain forms of analysis, to depend to some degree upon when a conscious observer witnesses an event. The classic of these types of problem is the Schroedinger's Cat thought experiment, which points out the curious quantum nature of things and asks at which point the probabilistic, indeterminant nature of quantum physics collapses into a single coherent state. (This controversy is well analyzed in the book Quantum Enigma: Physics Encounters Consciousness by Bruce Rosenblum & Fred Kuttner.)

Even among those who bring up the role of consciousness, however, an even deeper early controversy is often glossed over - these questions were viewed, among many of the most prominent founders of quantum physics, as profoundly mystical questions. This viewpoint is tackled in a paper published in the European Journal of Physics by Harvard historian Juan Miguel Marin ('Mysticism' in quantum mechanics: the forgotten controversy - abstract only).

Lisa Zyga covers the topic quite well in her article, Quantum Mysticism: Gone but Not Forgotten over at PhysOrg.com. Basically, Marin doesn't weigh in on the role of consciousness itself (being a historian rather than a physicist), but instead points out that the very fact that this controversy once existed shows that there are many different ways that science and religion can interact, instead of the "all or nothing" tug of war which seems so prevalent today. Marin suggests that, in part, this is a transition from the early 20th century Germanic worldview (which dominated theoretical physics of the early quantum era) with the Anglo-American viewpoint that has dominated physics since the Manhattan Project.

Apparently, weighing in on the science side of the science/religion split is the recent book by Victor J. Stenger, Quantum Gods: Creation, Chaos, and the Search for Cosmic Consciousness, written with the (seemingly) express purpose of debunking the mis-application of quantum physics to pseudo-religious hokum. I won't question the validity of Stenger's argument, having not yet read his book (it's sitting right here and I promise I'll get to it!), but I do think that Marin makes a valid point that physicists today are too quick to dismiss the entire debate over consciousness without really giving the complexities due intellectual credit.

What is without a doubt important, in an age where new age mysticism seeks to co-opt quantum physics as part of its support structure, is for scholars such as Marin and Stenger to clearly delineate the limits of this discussion. Even in the most extreme formulations, quantum physics interactions with consciousness do not grant anyone the ability to summon vast amounts of wealth just by thinking about it.