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On this page:

    (1) The Pioneer Anomalous Acceleration [2002/02/13]

    (2) Is Phobos still in orbit around Mars? [2002/05/04]

    (3) The Meta Philosophy of Science [2002/05/05]

See also:

    (4) The Meaning of the "speed of gravity" [2002/09/04]

    (5) "The Black Drop Effect" [2004/06/11]

The Pioneer Anomalous Acceleration

            Meta Research as an organization is always on the lookout for anomalies, and much of our research is directed by them. Of course, most anomalies turn out to have prosaic explanations. But it is the few that do not that have the potential to point us in the direction of new discoveries. Nonetheless, it seems important to assure our members that we are not unmitigated anomaly-proponents, and we rule out far more of them than the few we find occasion to report on. One such that has received considerable attention, especially on the internet, is the so-called “Pioneer anomaly”, an excess radial acceleration of the two Pioneer spacecraft toward the Sun with unknown origin.

             In investigating this anomaly, we first noted that the spacecraft unmodeled accelerations are so relatively large that they must be unique to very small bodies because the planets, moons, comets, and asteroids at any distance do not share these accelerations. Something of a similar (but not quite the same) size is seen in the Ulysses spacecraft with an orbit near Jupiter’s, but not in the Voyagers or other spacecraft. Yet the Pioneer anomalous acceleration is of a magnitude such as might be produced by an undiscovered planet inside the orbit of Neptune with a mass of 1.5 Jupiters, or more than 0.1% of the Sun’s own acceleration at the distance of the Pioneer spacecraft. The distinguishing characteristic of gravitational forces is that they induce the same acceleration in masses of all size. Therefore, whatever the anomalous acceleration may be, it is definitely not gravitational, and appears to be specific to certain spacecraft.

             A redshift interpretation is ruled out because a Hubble-rate-size change in all Earth clocks is inconsistent with pulsar timing data, which shows no consistent acceleration. Interstellar winds would be highly direction-dependent and affect only small masses, but the effect would be much smaller than either Pioneer sees, and unable to affect the Ulysses spacecraft. Hubble expansion, dark matter, and a variety of other exotic mechanisms are also inconsistent with the data. We also note that the effect is not uniquely associated with orbits of high eccentricity because several high-eccentricity asteroid orbits (e.g., Icarus) do not show it.

             A paper in the Los Alamos archive seems to explain the puzzle. See link. In brief, the anomalous acceleration may arise from radiation of waste heat by the on-board spacecraft RTG power generator. The Earth-pointing orientation of the distant spacecraft is what makes the force appear radial to the Sun. The waste heat explanation, or some variant of it, is surely correct because it matches the circumstances (choice of spacecraft affected, strength and specific signature of anomalous acceleration) so well. The waste heat itself is in excess of 2000 watts, and the anomaly requires an asymmetry in the dumping of that heat of just 60 watts, or about 3%. Those familiar with the spacecraft configuration can already account for about half that much asymmetry. Surely, some unnoticed factor will explain the remaining asymmetry because the alternative is that each of these particular spacecraft is affected by two different anomalies having a similar magnitude and direction. In any case, it seems safe to conclude that this anomaly is of interest to spacecraft trackers only, and not a symptom of some interesting astrophysical discovery still to be made.

2002/02/13

{Note added 2002/10/26: Click here to see the latest attempt to model this effect.]

(Note added 2008/04/21: Click here for the most recent developments.]

Is Phobos still in orbit around Mars?

[A response to a frequent question in our recent mail, occasioned by a current Internet hoax]:

    Meta Research is not an observatory and has no large telescopes. Moreover, the moons of Mars are too faint to be seen by any but the world’s largest telescopes except when they are close to Earth. And those largest telescopes are fully booked with work that does not include routine checks to make sure that all the solar system’s moons are still in place. However, when Mars was last close to Earth in June 2001, the moons were within range of some smaller and medium-sized telescopes, and were routinely observed throughout the spring and summer months, at least through the end of July. See, for example, this 2001 July 28 image on display at another web site. The Internet hoax that the moons had disappeared began well before that image, and is therefore proved false as far as we are concerned.

    The reason why such photos are so rare is the extreme difficulty of photographing a tiny target (Phobos) in the close vicinity of a light source a million times brighter (Mars). This feat is far outside the possibilities for most amateur telescopes even under the most favorable conditions. It took a 26-inch telescope (at the U.S. Naval Observatory) and a very experienced observer (Asoph Hall) to discover that the moons existed in the first place in 1876. Anyone having official need to know about recent photos taken for updates on the orbits of the moons with the 51-inch astrometric reflector of the U.S. Naval Observatory in Flagstaff, AZ could contact the U.S. Naval Observatory in Washington, DC or in Flagstaff and learn how many Mars images showing the moons were taken during the most recent period (in mid-2001) when Mars was close to Earth. The next opportunity for photos from Earth will occur just after mid-2003.

    The Mars Global Surveyor spacecraft in orbit around Mars (and itself a "moon of Mars", albeit an artificial one) last photographed Phobos in 1998, before its mapping mission began. Beginning in early 1999, the MGS spacecraft pointed its camera straight down at Mars and began its official mapping mission. It was not subsequently allowed to stray from this vertical nadir-pointing until the completion of the multi-year mapping mission. However, during the mapping, the spacecraft did photograph the shadow of Phobos sweeping across Mars on some occasions. See the inset image, posted to the MSSS/JPL/NASA official web site on 2002/03/17.

    Regrettably, Internet hoaxes are now quite common, and they hurt the credibility of all scientists. They work so well because so many people tend to believe something claimed with “authority” rather than withhold judgment until it can be checked out. Those who buy into the hoax then become the hoaxer’s unwitting allies, and will fiercely resist information that might show they had been duped. The result is that these rumors spread all over the world and get far more attention than they should. When I was in college 40 years ago, an informal competition arose periodically among my fellow students, usually around exam time, to see who could fool the most people with a hoax. Fortunately, they had no Internet to spread the hoax far and wide, so it usually died out quickly with a minimum number of “victims”. Today, we can no longer count how many people are taken in by these incidents.

2002/05/04

The Meta Philosophy of Science

[From the author's Preface in Dr. Tom Van Flandern's Dark Matter, Missing Planets and New Comets (1993; 2nd ed. 1999), available in the store at this site; updated 2002/05/05]:

    I began to form some hypotheses about what was wrong with these other bodies of knowledge [outside astronomy], and why. I particularly noted a regular practice of not re-examining the fundamental assumptions underlying a theory once it gained "accepted" status, almost no matter how incompatible some new observation or experiment might be. And I saw powerful vested interests in a "status quo" develop around certain accepted theories.

    It gradually became clear that a lot of people had a lot to lose if an accepted theory or practice were challenged: the authors of the original theory, whose names had become well-known; all those who published papers which reference or depend on the theory; journal editors and referees who have made decisions or criticized other works based on a theory; funding agencies which have paid for research which pre-supposes a theory; instrument builders and experiment designers who spend career time testing ideas which spring from a theory; journalists and writers whose publications have featured or promoted a theory; teachers and interested members of the public who have learned a theory, been impressed by the wonder of it, and who have no wish to have to teach or learn a new theory; and students, who need to find a job in their field of training.

    It has been my sad observation that by mid-career there are very few professionals left truly working for the advancement of science, as opposed to the advancement of self. And given enough people with strong enough interests, professional peer pressure takes over from there. Peer pressure in science, as elsewhere in society, consists of alternately attacking and ignoring the people who advocate a contrary idea, and discrediting their motives and/or competence, in order to achieve conformity. Even when it is not effective directly, it is usually successful at ensuring that the contrary person or idea gains few allies, and remains isolated. In short, those who may suspect the need for a radical change in an accepted theory have no interests or motivations as strong as those supporting the status quo. And members of the former group usually lack the background and confidence to challenge the latter group, who are the "recognized experts" in the field and well-able to defend their own theories.

    As if there weren't already enough inertia to major changes of models, I see yet another phenomenon -- new to our era of rapid progress in science -- which militates against change even in the face of overwhelming need for it. Few scientists consider themselves qualified very far outside their own areas of expertise. Since each expert can account for only a small portion of the data dealing with a model, he defers to the other experts to support the model in other areas. Few, if any, scientists have the breadth of knowledge to see the full picture for a given model. So the model remains supported because many individual authorities support it, none of whom have the expertise to criticize the model overall, and all of whom have the utmost confidence in the others collectively. Authorities can continue to multiply indefinitely, with no one taking responsibility for integrating all their combined knowledge. As a result, the existing models get perpetuated regardless of merit or the extent of counter-evidence, because "so many experts can't all be wrong." Thus each expert is persuaded to force-fit his own data into the accepted model, oblivious that the others are doing the same.

    However, I had learned by then to start being more open-minded toward new ideas, no longer dismissing them out of hand without strong enough reason that even the idea's proposer could understand. Whereas before it was rarely "worth my time" to deal with proposed new ideas, I now felt quite the opposite. This was chiefly because even in the process of proving that a new idea was false, I learned a great deal about the fundamentals underlying the challenged theory. I came to see the soft underbelly of many theories with a tough outer shell. I found a lot of unsuspected weaknesses.

    The first challenging new idea which I entertained as seriously viable was P.A.M. Dirac's proposal of the variability of the universal gravitational "constant." I performed a test of the idea using observations of the Moon's orbital motion around the Earth, and obtained results which supported Dirac's theory and seemed to be statistically significant. This experience led me to realize how fragile were the assumptions underlying the Big Bang and other theories of cosmology, when even the constancy of gravitation, the most important force in shaping the large-scale structure of the universe, had been called into question. And I saw that very few of my colleagues were taking seriously the idea that anything could be wrong at such a fundamental level. Their attitude was understandable, but unscientific.

    From my disturbing experiences with the insubstantiality of fundamentals in other fields, I learned how I could sometimes spot the bad accepted theories from a combination of their strangeness, a certain lack of providing true insight into the underlying phenomena, and a continuing need to do "maintenance theorizing" to patch the theory in ever stranger ways as new data became available. I later added "derivation from inductive reasoning" as additional grounds for holding a theory suspect. Many of the accepted astronomical theories in use today are "suspect" by all these criteria. I also learned how to proceed when one encounters such a theory: Revert to the principal investigative tools of science and scientists, by means of which we try to separate good theories from bad ones.

    These are embodied in the Scientific Method, a process that involves competitive testing of all ideas. Most scientists understand, at least abstractly, the importance of testing. The part they have forgotten, or were never taught because too many major theories in too many fields would be called into question if it were, is controls on testing. This is the step in which the test is designed in such a way that the expected outcome, also called the “bias of the experimenter”, cannot influence the actual outcome. Instead, it has become common practice to question or challenge data that leads to an unexpected outcome while not even checking data or procedures that give the expected result. Even more common is an ad hoc patch to the idea being tested to accommodate the outcome. Naturally, such a patch completely invalidates the test, and requires some independent test with new data. But all too commonly, the result of the original test is cited as evidence supporting the patched idea. Such is the state of mainstream science today.

2002/05/05