Wednesday, March 31, 2010

The "Van Allen Hypothesis": Abandoned Science Finds New Life in Pseudoscience?

I have on occasion heard a reference in e-mails from the Electric Universe (EU) supporters about something called the “Van Allen Hypothesis”.  I was able to find a reference to the specific paper in this old thread on the ThunderBolts forum, titled “Question about the Current Powering the Sun”, where they are discussing my document “The Electric Sky: Short-Circuited” (DwCiA: Electric Cosmos).  The reference for the Van Allen hypothesis is
In the paper, Dr. Alexeff describes a presentation by James Van Allen, apparently from the early 1990s, where Van Allen described a linear relationship between the rotational angular momentum and the magnetic moment of celestial bodies, i.e. that the magnetic moment of a spinning object is directly proportional to its angular momentum.  That this relationship appeared to hold across many orders of magnitude for a number of celestial bodies was something of a mystery (it should be noted that the error bars on this 'agreement'  also stretched across two orders of magnitude (a factor of 100) in both magnetic moment and angular momentum measurements.  This means that if U is value of the angular momentum, then U and 100*U, would both be considered as in 'agreement' with the model.  Quite a large range.

Faint bells went ringing at the edge of my consciousness.  I had heard this before.  But where?  I recently discovered the missing piece and decided  to assemble a more complete chronology.

First, there is only one publication I have found in the years prior to Alexeff's reference from the 1990s where Van Allen mentions the idea of rotation connected to magnetic moment.
The reference is somewhat misleading, as Van Allen does not appear to be an original author of the paper, but his contribution is a short two paragraphs appended after the references:
"Although Brown properly cites prior evidence against the validity of the Blackett hypothesis, I continue to feel that our determination of an upper limit to the magnetic moment of Mars has a certain cogency in an astronomical context.  The test on Mars is one which I have aspired to make since I first heard Professor Blackett lecture on this subject some 20 years ago.
In the face of all the negative evidence concerning the validity of the Blackett hypothesis, Brown's suggestion that it may apply to Earth and Jupiter seems untenable.''
The bells at the edge of my consciousness are ringing loudly now.  The Blackett Hypothesis!

So while Alexeff attributes the idea to Van Allen, Van Allen himself attributes it to P.M.S. Blackett.  In addition, Van Allen dismisses the Blackett Hypothesis as not having sufficient experimental and observational support.  Of course, this does not mean that the 'agreement' described above is not interesting, just that it probably does not indicate new fundamental physics as some would like to believe.

But what about Blackett's formula?  Blackett published the idea in 1947.
Blackett's equation can be written
where P is the magnetic moment, U is the angular momentum, G is Newton's gravitational constant, c is the speed of light, and beta was a dimensionless constant with a value that seemed to range between perhaps 0.3 and 1.2.  The relation generated strong interest because it seemed to connect gravitation, by way of Newton's G, and electromagnetism - a possible key to a Unified Field Theory!

Much experimental & theoretical work followed, but the final result was that the relationship did not hold up under detailed examination and interest waned after a few years.  The most troublesome aspect for the idea was that the Earth and solar magnetic fields were known to reverse their polarity over time, a clear problem unless the rotations reversed as well (something we don't observe with the solar magnetic cycle that reverses approximately every eleven years).  In addition, since the magnetic moment and angular momentum are vector quantities (they have a direction as well as a magnitude), there is the question of how this relationship can hold since most of the celestial bodies where we've measured magnetic fields do not have their rotation axis aligned in the same direction as their magnetic axis.  We know this is true for the Earth (where they differ by almost ten degrees in angle) and other planets in our Solar System.

Why was the Blackett formula familiar to me?  The Blackett formula was a key idea behind the operation of the spindizzy (Wikipedia), a fictional interstellar drive used in James Blish's “Cities in Flight”(Wikipedia). I had read this book many years ago.

But the story isn't over.  Was Blackett the first to think of this?  The idea that rotational motion might be fundamentally linked to magnetic fields was actually suggested in papers going back to around 1900!
Many of these papers explored ideas such as charge separation created by gravitation in a massive body.  The body rotation would then generate a current and subsequently a magnetic field.  The idea did not meet with any success, theoretically or experimentally.

So what about the amazing 'agreement' of angular momentum and magnetic moment? 

The Universe is apparently full of interesting numerical 'coincidences', one of the most famous of the 20th Century being Dirac's Large Numbers Hypothesis (Wikipedia).  This idea inspired a number of avenues of inquiry between cosmology and fundamental physics, but none had particular experimental success.

But most likely, the relationship is a consequence of similarity in the underlying mechanisms in the generation of celestial magnetic fields.  Consider Kepler's 3d Law (Wikipedia),
T^2/R^3 = constant
where T is the orbital period in years and R is the radius of the orbit in Astronomical Units, for all the planets of our Solar system.  Kepler's 3rd Law is true to far higher precision than the Blackett relationship for celestial bodies.   Kepler's 3rd Law would eventually be discovered as a consequence of Newton's gravitation and force laws (actually, Newton derived the law of gravity based in part on the Kepler relationship).  Similarly, I suspect the Blackett relationship ties to an underlying aspect of the dynamo mechanism of magnetic field generation, but due to the large range of the 'agreement', it is clearly only an approximate characteristic.

Because there are physical constants that relate to how physical properties are coupled together, a surprising number of properties can be approximated to within orders-of-magnitude without regard to the details of the interaction.  For example, the fundamental timescale of a gravitating system can be approximated by sqrt(G*M/R^3) where M is the mass of the system and R is its radius.  This kind of dimensional analysis trick is why creationist Russ Humphrey's magnetic field model (1984) generated reasonable values for some observables regardless of the huge errors in the details.  See some of examination of this in Tim Thompson's analysis available on Talk.Origins.

One of the problems in science is that successful researchers often explore many ideas and 'hunches' that turn out to be dead ends.  Very often, the researcher does not publish the results of these dead-end inquiries.  This makes it easy for someone to 'discover' or re-discover a previously dismissed idea, many years later, thinking it is new.

[Disclaimer 1: This article is not meant to suggest that Dr. Alexeff is a supporter of Electric Universe claims, merely that this particular paper of his has been used by some EU supporters as evidence of more bizarre EU claims.  In spite of some rather odd assumptions (cylindrical planets, dependency of field on the external plasma), Dr. Alexeff presents the mathematical details of his analysis for examination by the scientific community.  This is the professional behavior expected in the scientific community, but it is generally NOT exhibited by EU supporters.]

[Disclaimer 2: It has been brought to my attention that ideas which appear in the Thunderbolts forums are not necessarily ideas supported by the Electric Universe 'experts'.  Since EU provides no objective standards of testing which anyone can apply, it appears that only those anointed as the official voices of EU may decide what is and is not part of the theory.  I do not know if Dr. Alexeff's work is regarded as a official part of EU.]

2 comments:

Leroy Ellenberger said...

Curiously enuf, Velikovsky believed geomagnetism was due to the rotating, charged Earth; Juergens and Warlow agreed. See "Magnetism, Dynamos & Neptune" . Since Blackett's hypothesis did not involve electric charge, I did not discuss him; and when I wrote this in 1991 the EU crowd was nowhere to be seen or heard so they were not included in my survey.

W.T."Tom" Bridgman said...

A link to "Magnetism, Dynamos & Neptune"