Electrostatic magnetic ion attraction

Submitted by Nicholas C. Darnton (inactive) on Monday, 2/1/2010, at 10:40 AM
bomb "detector"

Iraqis are using a bomb detector that operates on the principle of "electrostatic magnetic ion attraction".  The physics behind this device is a mystery, since the existence of magnetic ions is unknown to conventional science, so I can't comment on why explosive material would have more (or fewer?) magnetic ions than other materials – which is presumably the basis for bomb detection. 

The company that makes the apparatus acknowledges your skepticism: "One of the problems we have is that the machine does look primitive. We are working on a new model that has flashing lights."  That new model may not be enough to save the company's director, though.  This NYT editorial implies that corruption – rather than "legitimate" bad science – explains this fiasco. 

Other sources for bad science

Submitted by Nicholas C. Darnton (inactive) on Thursday, 1/28/2010, at 3:32 PM

I'm certainly not the only person interested in bad science.  There are many blogs or bloglike sites that discuss bad science; a fair number of these are quite intemperate.

  1. Csicop
  2. Ben Goldacre's Bad Science blog and his column in The Guardian
  3. NCBI ROFL.  Not really bad science, but if you understand the name you'll find it funny.
  4. Depleted Cranium
  5. BadHomeopathy and BadPsychics
  6. Bad Astronomy

And there are many books that discuss bad science in general, or in specific.

Misconceptions over conservation of energy

Submitted by Nicholas C. Darnton (inactive) on Thursday, 1/28/2010, at 1:44 PM
Electric car ramp

Generate power from passing cars. 

Though the initial press release reasonably touted this as a way to get power to street lights in remote, off-grid locations, the idea was seized on by people with no comprehension of energy conservation as a "free" way to generate power. 

The "best" proposal combines not only capturing the passing cars' energy in pneumatic storage tanks but also powering the cars themselves with air pressure.  The logical next step is to eliminate the cars altogether and build a perpetual motion machine.

 Nightclub

Note that there are some legitimate situations where you could produce net energy this way – basically, you can extract a bit of a car's kinetic energy just before the car was going to brake anyway.  Even if you did come out ahead in purely energy terms, though, it's pretty unlikely that replacing the output of large, efficient, highly regulated power plants by that of poorly maintained, gasoline-burning internal combustion engines will benefit the environment.

A related plan harnesses dancers' energy to power a nightclub.  Well, to power a small part of a nightclub, anyway.

Perpetual motion machines

Submitted by Nicholas C. Darnton (inactive) on Thursday, 1/28/2010, at 1:44 PM

This is an ad hoc list of physics-violating devices that have achieved sufficient prominence to make it onto the web.  Many have associated comment streams where you can read paranoid posts about sinister energy or oil cabals (OK – the oil cabal actually exists and even has its own web site) suppressing inventions that would free the world from the tyranny of energy scarcity.  In fact, the DARPA site for Breakthrough Propulsion Physics even includes a Cautionary Note:

"On a topic this visionary and whose implications are profound, there is a risk of encountering, premature conclusions in the literature, driven by overzealous enthusiasts as well as pedantic pessimists ... Avoid works with broad-sweeping and unsubstantiated claims, either supportive or dismissive."

Wikipedia has a short historical introduction to perpetual motion devices.  I have included only a few examples here, mostly just for fun. 

folding wheel

Eric Krieg has an extensive list of perpetual motion machines, but seems to have abandoned his compilation around 2003 after some hundred entries.  Krieg seems to conclude that most of these devices' "inventors" were nothing more than scam artists trying to bilk investors out of their money.  Luckily, my students understand conservation of energy and won't be so easily parted from their lucre.   On a personal note: I had hoped the inventors were merely optimistic, or perhaps insane; apparently I'm naive.

Frustration with the whack-a-mole quality of these schemes is not new.  As far back as 1775, the French Academy of Sciences proclaimed that it would no longer consider any purported perpetual motion devices, because

"This sort of research . . . has ruined more than one family, and in many cases mechanics who might have rendered great services have consumed their fortune, their time, and their genius on it."

Back then, perpetual motion machines were all mechanical, like the folding wheel (see figure).  Nowadays most – but not all – perpetual motion machines are electric or magnetic.

Please note that perpetual motion is possible, if you eliminate friction (for mechanical systems) or resistance (for electrical systems).  We know of exotic materials that are (under appropriate conditions) superfluids or superconductors: these will sustain flow or current forever with no loss.  However, these systems still do not produce any excess energy, and any energy extracted from them directly diminishes the amount remaining.

Energy for nothing

Free EnergyInterestingly, proponents of these devices split into two camps: those who admit that they violate the known laws of physics, and those who claim to use only standard physical principles.  The former seem to revel in rebutting conventional science, while the latter portray themselves as clever engineers who merely exploit obscure loopholes in "normal" science.

  1. A clearing house for schemes that promise to produce more energy than they consume. These are apparently called over unity devices.  Also weirder stuff that seems to veer toward UFOlogy.
  2. Orbo: some kind of rotary mechanical / electromagnetic device.  Proof that a nicely designed website doesn't make something true.  I'd like to give Steorn (the company responsible for this device) credit for submitting the Orbo for review by a nonpartisan jury, but a few months after jury concluded that the device "[has] not shown the production of energy",  Steorn claimed to have "resolved the key technical problems" and plans to market the Orbo in the near future.
  3. Motionless Electrical Generator.  Some kind of zero-point energy device (extracting energy from the vacuum).  Proof that acceptance by the U.S. Patent Office doesn't make something true.  Bonus: the same guy who invented the MEG can also cure cancer.
  4. Lutec Electricity Amplifier: some kind of coupled AC/DC motor.  Proof that acceptance by lots and lots of patent offices doesn't make something true.
  5. Cold fusion: the claim that catalysts can cause deuterium fusion at normal temperatures and pressures.  This is a completely different category of unconventional energy generation, since there is no fundamental physics reason why cold fusion cannot exist.  Fusion certainly happens in the Sun and in the lab (in tokamaks), though at very high temperatures and pressures, and it certainly liberates large amounts of energy.  Fusion may well also occur at STP, but under normal conditions the rate of cold fusion is negligibly small, and it's hard to see why a catalyst or electric current would increase that rate.  Most physicists would love cold fusion to be real; unfortunately, it appears that it's not.
  6. Hydrino power.  Blacklight Power claims to have discovered a state of molecular hydrogen that has a lower ground state than the one we learn about in physics or chemistry: the hydrino.  They have a simple, highly exothermic chemical reaction that produces hyrinos.  This doesn't violate any laws of thermodynamics – if the hydrino exists, it would be possible to build reactors that produce lots of cheap energy – but the hydrino is not an allowed solution to the laws of quantum mechanics as they are currently understood.  Blacklight Power has a rebuttal for that, of course.  Bonus: the company is located just down the road from my hometown of Princeton, NJ. 
  7. Too-simple ways to increase your car's mpg:
    1. Magnetic treatment of gasoline.  Not a perpetual motion device, but claims to improve fuel efficiency (and reduce carbon buildup and improve cooling system performance).  Apparently magnetism is so mysterious that people are willing to believe it can do just about anything.  Details to follow in Physics 17 or 24. 
    2. Plug-in mileage enhancer.  Insert in cigarette lighter and it increases fuel efficiency up to 30 percent, increases torque, and reduces emissions.  Bonus: improves car audio quality, too!

Momentum for nothing

  1. DARPA wormholeDARPA's now-defunct "Breakthrough Propulsion Physics" Program reads like something out of The X-Files.  DARPA's official technical site is rather heavy; the layperson's summary is more accessible but light on the science; Wikipedia does a pretty good synopsis.  Bear in mind that DARPA attempts a lot of really weird stuff that never pans out so the fact that it launched a program like this should not be taken as U.S. government endorsement of any of the physics therein.
  2. The Dean Drive looks like it falls under the DARPA category of "Oscillation Thrusters" characterized as "Non-Viable".
  3. EM-drive.  Radiation pressure within a closed, tapered cavity supposedly causes the cavity to accelerate.

Reflection FAIL

Submitted by Nicholas C. Darnton (inactive) on Wednesday, 1/27/2010, at 12:38 PM
Physics for future presidents

Examine the book cover to the right closely; you can click on it for a larger version.  Notice the problem?

Let's start by stipulating that it was unreasonable to actually photograph a real reflection of the Presidential Seal, so the publisher was justified in photoshopping it.  There are three schools of thought about the actual resulting book cover:

  1. Most charitable: this is all the publisher's fault.  The author would have spotted this, but no one on the editorial side noticed it.  If only the illustrator had read the book (or taken the course it's based on) this would never have happened.
  2. Less charitable:  at some point, some involved in this mishap realized that the reflection should have been inverted, but it was too much trouble to fix.
  3. Least charitable: the publisher knew the reflection job was botched but figured that the general public was
    1. too stupid to notice, and/or
    2. too stupid to comprehend reversed letters if the cover were fixed.

I understand the rationale for the reversed lettering on the front of ambulances: you want to avoid the split-second of incomprehension when a driver sees the ambulance in the rearview mirror.  But is the publishing industry really so cut-throat that the fraction of a second necessary for cognitive processing of a reversed Presidential Seal would have materially affect the sales of this book? 

This one is even harder to explain.

Why you should always write down units

Submitted by Nicholas C. Darnton (inactive) on Tuesday, 1/26/2010, at 11:48 PM
Mars orbiterYou're probably calculating everything in MKS (meters, kilograms and seconds) and I could probably guess what units you are using, but if you neglect units then
  1. you're giving up a chance to catch boneheaded algebra errors, and
  2. this could happen to you, causing international embarrassment.

Coin vortex

Submitted by Nicholas C. Darnton (inactive) on Tuesday, 1/26/2010, at 11:42 PM
coin vortex

Coin spirals (such as the one here or here) are often claimed to mimic the physics of an orbiting planet, including by people who should know better.  I vaguely remember being told this as an undergraduate as well.  This is exactly half true.

(1)  Since the funnel drops towards the center, the potential energy of a coin rolling on the surface decreases; since energy is conserved, kinetic energy must increase and the coin speeds up.  This happens in planetary orbits as well, and – assuming the coin funnel shape is similar to the gravitational potential, i.e., proportional to 1/r2 –  the coin funnel is a good representation of this part of celestial mechanics.

(2)  In Newton's law of gravitation, the force of gravity is purely central and therefore produces no torque, so angular momentum is conserved.  This is not the case for the coin funnel, since frictional forces between coin and funnel do produce a torque on the coin; in fact, if you measure the angular momentum of a coin in one of the funnel videos above, you will find that it increases with time.  This is a clear violation of conservation of angular momentum and is dramatically different from planetary motion.  It's not a huge effect but it is definitely measurable.  I don't see any way to fix this without making the funnel frictionless.