Posted: Feb 16, 2012 6:32 am
Gravity As A Resultant Of Rotation
Gravity is a phenomenon that has exercised many scientific minds over the past 300 years, and even today, a truly unified view of gravity is proving, for a range of reasons, to be somewhat elusive. It is not surprising, therefore, that one or two off-the-wall ideas have arisen, and it is one of those ideas, along with its concomitant failure, that I intend to present here.
This idea was the brainchild of one Patrick Maynard Stuart Blackett, a physicist of considerable renown, whose work encompassed such diverse fields as the physics of cloud chambers, operational research, palaeomagentism, and the behaviour of cosmic rays. A protegé of none other than Ernest Rutherford, Blackett was one of the first people to provide evidence of transmutation of atoms under conditions of intense neutron flux, and thanks to his work with Giuseppe Occhialini, he became one of the first physicists to understand the nature of antimatter.
However, whilst he enjoyed a number of successes, one of his ideas proved to be a failure. It led to him moving on to develop high-quality and high-sensitivity magnetometers, for measuring extremely small magnetic fields, and in turn in his later career to produce notable results in the field of geophysics. In that sense, the idea in question was not a complete failure, but it failed with respect to its ambitious goal, and this failed hypothesis is the topic of my article.
I refer everyone to the following paper:
The Magnetic Field Of Massive Rotating Bodies by P. M. S. Blackett, Nature, 159: 658-666 (17th May 1947)
In this paper, Blackett expounded upon the existence of a relationship between magnetic moment (represented in the following equations by P) and angular momentum (represented in the following equations by U). Measurements taken for a small number of planetary and stellar bodies, led to the possibility that a general law existed, coupling P and U for all rotating bodies. The values were found to be a close fit to the following equation:
P = (βU/2c)G½ (in cgs units)
where β is a constant whose value is close to 1, c is the speed of light, and G is Newton's constant of universal gravitation. The reason that this equation was of interest, was because it admitted of an interesting rearrangement, of the form:
G = (2Pc/βU)2
and thus presented the interesting possibility that gravity and magnetism were nothing more than a consequence of angular momentum. If true, then this would revolutionise physics, and consequently, Blackett set out to discover whether or not the original relationship was merely coincidence, or a pointer to a general and universal physical phenomenon.
The problem, of course, is that gravitational fields are extremely weak. Likewise, any magnetic field emanating from a rotating body, according to this idea, would also be extremely weak, unless that rotating mass was of planetary size or beyond. Since determining the emergence of an increased gravitational field around a rotating mass in the laboratory was simply beyond the scope of any empirical test, Blackett opted to search for a magnetic field instead, one emanating from a body previously possessing no intrinsic magnetic field, but which, if the above equation was indeed a universal law, would emerge once the rotating body possessed sufficient angular momentum. Blackett determined that sufficiently sensitive instruments would detect such a magnetic field, provided that the body being used in the experiment was [1] of high material density, and [2] given a large angular velocity, resulting in large angular momentum, and a magnetic field that, whilst weak, would be detectable beyond the bounds of experimental error.
Thus the stage was set for Blackett's experiment. Which is covered in this paper:
A Negative Experiment Relating To Magnetism And The Earth's Rotation by P. M. S. Blackett, Philosophical Transactions of the Royal Society of London Part A, 245: 309-370 (16th December 1952) [Abstract available here]
So, the experiment was considered a failure, with respect to the matter of establishing a causal link between gravitation, magnetism and angular momentum. Blackett, having determined the result to be a failure, then moved on to the matter of using his new, extremely sensitive magnetometers to perform geophysical research, as the last sentence of the abstract above alludes to. Blackett decided that further pursuit of this idea was pointless, and considered the matter settled by the above 1952 paper.
Why is this failed experiment of such interest? First, it became a focal point for the later writings of the science fiction author James Blish, whose monumental Cities in Flight series features an anti-gravity drive based, purportedly, upon the rearrangement of the Blackett equation, and the realisation thereof in machinery. In Blish's fictional universe, Blackett's work is subject to re-evaluation, courtesy of a truly bizarre experiment, involving the erection of a solid platform, situated, of all places, on what is very loosely termed the 'surface' of Jupiter, an engineering undertaking involving the construction of an artefact approximately the size of metropolitan Los Angeles, amidst the turmoil of Jupiter's extremely hostile atmosphere!
Second, the hypothesis in question has become, in more recent years, another of those 'fringe' theories, resurrected from its grave and wheeled about on castors, by various individuals, no doubt salivating at the thought of cooking up an anti-gravity drive in the living room. That they stand even less chance of achieving this aim, than I do of being the next occupant of Scarlett Johanssen's bed, apparently deters them not. Doubtless both Blackett and Blish would, if they were still alive, view with a certain puzzled amusement, the spectacle of various individuals beavering away to try and make the spindizzy a reality, which would be wonderful if it were achievable, but, Blackett thought better of the matter in 1952, and decided to choose the path of paying attention when reality told him that an idea was not worth pursuing. An object lesson that sadly, will almost certainly not be learned by the very people who need to.
References:
[1] The Magnetic Field Of Massive Rotating Bodies by P. M. S. Blackett, Nature, 159: 658-666 (17th May 1947)
[2] A Negative Experiment Relating To Magnetism And The Earth's Rotation by P. M. S. Blackett, Philosophical Transactions of the Royal Society of London Part A, 245: 309-370 (16th December 1952)
Gravity is a phenomenon that has exercised many scientific minds over the past 300 years, and even today, a truly unified view of gravity is proving, for a range of reasons, to be somewhat elusive. It is not surprising, therefore, that one or two off-the-wall ideas have arisen, and it is one of those ideas, along with its concomitant failure, that I intend to present here.
This idea was the brainchild of one Patrick Maynard Stuart Blackett, a physicist of considerable renown, whose work encompassed such diverse fields as the physics of cloud chambers, operational research, palaeomagentism, and the behaviour of cosmic rays. A protegé of none other than Ernest Rutherford, Blackett was one of the first people to provide evidence of transmutation of atoms under conditions of intense neutron flux, and thanks to his work with Giuseppe Occhialini, he became one of the first physicists to understand the nature of antimatter.
However, whilst he enjoyed a number of successes, one of his ideas proved to be a failure. It led to him moving on to develop high-quality and high-sensitivity magnetometers, for measuring extremely small magnetic fields, and in turn in his later career to produce notable results in the field of geophysics. In that sense, the idea in question was not a complete failure, but it failed with respect to its ambitious goal, and this failed hypothesis is the topic of my article.
I refer everyone to the following paper:
The Magnetic Field Of Massive Rotating Bodies by P. M. S. Blackett, Nature, 159: 658-666 (17th May 1947)
In this paper, Blackett expounded upon the existence of a relationship between magnetic moment (represented in the following equations by P) and angular momentum (represented in the following equations by U). Measurements taken for a small number of planetary and stellar bodies, led to the possibility that a general law existed, coupling P and U for all rotating bodies. The values were found to be a close fit to the following equation:
P = (βU/2c)G½ (in cgs units)
where β is a constant whose value is close to 1, c is the speed of light, and G is Newton's constant of universal gravitation. The reason that this equation was of interest, was because it admitted of an interesting rearrangement, of the form:
G = (2Pc/βU)2
and thus presented the interesting possibility that gravity and magnetism were nothing more than a consequence of angular momentum. If true, then this would revolutionise physics, and consequently, Blackett set out to discover whether or not the original relationship was merely coincidence, or a pointer to a general and universal physical phenomenon.
The problem, of course, is that gravitational fields are extremely weak. Likewise, any magnetic field emanating from a rotating body, according to this idea, would also be extremely weak, unless that rotating mass was of planetary size or beyond. Since determining the emergence of an increased gravitational field around a rotating mass in the laboratory was simply beyond the scope of any empirical test, Blackett opted to search for a magnetic field instead, one emanating from a body previously possessing no intrinsic magnetic field, but which, if the above equation was indeed a universal law, would emerge once the rotating body possessed sufficient angular momentum. Blackett determined that sufficiently sensitive instruments would detect such a magnetic field, provided that the body being used in the experiment was [1] of high material density, and [2] given a large angular velocity, resulting in large angular momentum, and a magnetic field that, whilst weak, would be detectable beyond the bounds of experimental error.
Thus the stage was set for Blackett's experiment. Which is covered in this paper:
A Negative Experiment Relating To Magnetism And The Earth's Rotation by P. M. S. Blackett, Philosophical Transactions of the Royal Society of London Part A, 245: 309-370 (16th December 1952) [Abstract available here]
Blackett, 1952 wrote:The discovery by Babcock of the magnetism of certain rapidly rotating stars led me to study the hypothesis, first clearly discussed by Schuster and by Wilson, that the magnetism of rotating astronomical bodies might be due to some new and general property of matter. The well-known theoretical difficulties attending such a view were matched by the difficulty of finding a quantitative explanation of even the earth's magnetic field in terms of the known laws of physics. A detailed study of the possibility of making a direct test of the Schuster-Wilson hypothesis, by measuring the very small magnetic field of the order of 10-9 G which would be produced by a rotating body of reasonable size in the laboratory, led me to conclude that the experiment would perhaps be possible but would certainly be exceedingly difficult. However, a much easier but still worth-while subsidiary experiment presented itself. This was to test whether a massive body, in fact a 10 × 10 cm gold cylinder, at rest in the laboratory and so rotating with the earth, would appear to an observer, also rotating with the earth, to produce a weak magnetic field with a magnitude of the order of 10-8 G. That such a field might exist is a plausible deduction from a particular form of the Schuster-Wilson hypothesis considered in some detail by Runcorn and by Chapman. This paper describes the design, construction and use of a magnetometer with which this 'static-body experiment' was carried out. Since few detailed studies of the design of sensitive magnetometers to measure steady fields appear to have been made since the days of the classical experiments of Rowland and of Eichenwald, I found it necessary to investigate the theory and use of such an instrument in considerable detail. The bulk of this paper, that is, Section 2 to 5, is concerned with this instrumental study. The actual static-body experiment is described in Section 6. and it is there shown that no such field as is predicted by the modified Schuster-Wilson hypothesis is found. This result is in satisfactory agreement with the independent refutation of the hypothesis by the measurements by Runcorn and colleagues of the magnetic field of the earth underground. When the magnetometer was completed it was found to be very suitable for the measurement of the remanent magnetism of weakly magnetized specimens, in particular certain sedimentary rocks.
So, the experiment was considered a failure, with respect to the matter of establishing a causal link between gravitation, magnetism and angular momentum. Blackett, having determined the result to be a failure, then moved on to the matter of using his new, extremely sensitive magnetometers to perform geophysical research, as the last sentence of the abstract above alludes to. Blackett decided that further pursuit of this idea was pointless, and considered the matter settled by the above 1952 paper.
Why is this failed experiment of such interest? First, it became a focal point for the later writings of the science fiction author James Blish, whose monumental Cities in Flight series features an anti-gravity drive based, purportedly, upon the rearrangement of the Blackett equation, and the realisation thereof in machinery. In Blish's fictional universe, Blackett's work is subject to re-evaluation, courtesy of a truly bizarre experiment, involving the erection of a solid platform, situated, of all places, on what is very loosely termed the 'surface' of Jupiter, an engineering undertaking involving the construction of an artefact approximately the size of metropolitan Los Angeles, amidst the turmoil of Jupiter's extremely hostile atmosphere!
Second, the hypothesis in question has become, in more recent years, another of those 'fringe' theories, resurrected from its grave and wheeled about on castors, by various individuals, no doubt salivating at the thought of cooking up an anti-gravity drive in the living room. That they stand even less chance of achieving this aim, than I do of being the next occupant of Scarlett Johanssen's bed, apparently deters them not. Doubtless both Blackett and Blish would, if they were still alive, view with a certain puzzled amusement, the spectacle of various individuals beavering away to try and make the spindizzy a reality, which would be wonderful if it were achievable, but, Blackett thought better of the matter in 1952, and decided to choose the path of paying attention when reality told him that an idea was not worth pursuing. An object lesson that sadly, will almost certainly not be learned by the very people who need to.
References:
[1] The Magnetic Field Of Massive Rotating Bodies by P. M. S. Blackett, Nature, 159: 658-666 (17th May 1947)
[2] A Negative Experiment Relating To Magnetism And The Earth's Rotation by P. M. S. Blackett, Philosophical Transactions of the Royal Society of London Part A, 245: 309-370 (16th December 1952)