Tibor Pacher has been kind enough to publish the text of my public lecture in Aosta, Italy on his PI Club site. The lecture took place at the Aosta town hall and wasn’t part of the ongoing conference just down the street, although some conference participants attended. It’s a broad overview of earlier work on interstellar flight. My intention was to acquaint non-scientists with the fact that the subject has been under study for decades in ways that do not violate the laws of known physics. A major challenge is how to scale some of the colossal engineering involved down to realistic levels.
Although I only touched upon it in the lecture, I often talk about the twin tracks of interstellar studies. The first track comprises work that tries to scale current technology up for an interstellar mission. The second track is oriented toward examining physical laws in hopes of finding potential breakthroughs that current theory doesn’t allow. No one knows if such breakthroughs are possible, but we want to keep banging on prevailing ideas to see if there are areas that need revision.
Into the Eclipse
On that score, be aware of tomorrow’s total solar eclipse, which gets particular attention because six Chinese teams will be monitoring the event to look for the possibility of anomalous gravitational effects. Does gravity undergo a slight change during a total eclipse? The French physicist Maurice Allais noted unusual behavior in a swinging pendulum back in 1954 during the eclipse that passed over Paris that year. Since then, measurements to pin down what is going on have been inconclusive. A New Scientist story provides more background, as does this NASA page, which details subsequent, often contradictory follow-ups.
The first step in this kind of investigation is to find out whether the anomaly actually exists. The six Chinese monitoring sites will include gravimeters and pendulums, and will encompass a large enough area (3000 kilometers between those that are farthest apart) that local changes in weather or problems with instrumentation should be ruled out. If General Relativity is in need of a tweak, these results could provide a clue.
Explaining an Anomaly
Back in 2004, Chris Duif (Delft University of Technology, The Netherlands) looked at anomalous eclipse observations to see whether they could be explained by seismic disturbances, meteorological conditions, changes in the geomagnetic field or other possibilities. He found none of these solutions satisfactory, and went on to write:
Although, despite all proposed conventional explanations fail to explain the observations either qualitatively or quantitatively, it is still possible that the reported anomalies will turn out to be due to a combination of some of these effects and instrumental errors. And, of course, there may be yet unidentified conventional causes which play a role. The judgment of some of the experimental results is hampered by the lack of a statistical analysis and/or data of sufficient length. Nevertheless, there exist some strong data which cannot be easily explained away.
So we’ll see what turns up in China. New Scientist quotes Tang Keyun (Chinese Academy of Sciences), as saying: “If our equipment operates correctly, I believe we have a chance to say the anomaly is true beyond all doubt.” That would be a fascinating result, and one that would lead to a great deal of new theorizing about how to incorporate the eclipse anomaly into our current views on how gravity works.
The Duif paper is “A review of conventional explanations of anomalous observations during solar eclipses,” available online.