Spinor Info

I spent a part of yesterday afternoon speed-reading Konstantin Kakaes’s new e-book, The Pioneer Detectives. It’s a short book (still well worth the $2.99 Kindle price) but it reads very well and presents a fair picture of our efforts researching the origin of the anomalous acceleration of the Pioneer 10 and 11 spacecraft.

Yes, I was one of those “detectives”. (In fact, I still consider myself one, as I don’t believe our job is quite done yet; we still owe the community a detailed account of our research and an update of our Pioneer Anomaly review before we can move on with a clean conscience.) So I have an insider’s view of this very intriguing story.

I had a chance to talk with Kakaes at length when he visited me here in Ottawa last year. Over the years, I learned to be apprehensive when talking to journalists; often, the words they put in your mouth bear little resemblance to what you actually said to them when interviewed. I was relieved that this was not the case now: at no time did I feel compelled to cringe while reading the book.

So I really enjoyed Kakaes’s telling of our story. Indeed, I think I learned a thing or two about presenting a complex subject to a non-specialist audience. Kakaes, an accomplished science journalist, manages to do so without dumbing it down with excessive oversimplifications.

One person whose views may not be as favorable is the original discoverer of the Pioneer anomaly, John Anderson. I am told that Anderson is not fond of our results. Kakaes believes that this is because Anderson is “blinded by his desire to believe in something new, in something unexplained. He wants so badly not to know.” Yes, scientists are people, too, and the prospect that a discovery you made, once thought profound, may just be an engineering fluke is not an easy one to swallow. Kakaes does what a responsible journalist must do: he tries to paint an objective picture, which sometimes includes unflattering bits. Yet I think that John Anderson has more scientific integrity than Kakaes gives him credit for.

And to be perfectly honest, I am also disappointed with our own results. When I first read about the Pioneer anomaly (as an outsider, long before my involvement) it seemed to fit perfectly into the big scheme: namely that perhaps the same physics that was responsible for significant deviations from Einstein’s and Newton’s predictions on cosmological and galactic scales might also be responsible for a small but measurable deviation here in the solar system. This was a fantastic prospect!

Sadly, it was not to be. What once seemed like a revolutionary, paradigm-shifting result has been reduced to a small footnote in the history of gravitational physics. Yet I think that our story is nonetheless intriguing. Kakaes seems to think so, too, judging by his book. A book that I am happy to recommend.

In all the excitement (okay, I wasn’t that excited. But, I was busy) I almost forgot to celebrate an anniversary: it was 40 years ago on April 5 that Pioneer 11 was launched at Cape Canaveral.

In a recent Letter to the Editor published in the newsletter of the American Physical Society, a correspondent suggested that Pioneer 11 may still reveal some anomalous behavior. I do not believe this to be the case. While it is true that our investigation of Pioneer 11 was not as thorough as our investigation of Pioneer 10 (due, in part, to the fact that we have less Doppler data from Pioneer 11) there are no statistically significant inconsistencies.

This Letter also reveals two misconceptions about the anomaly. One is that if the anomaly is Earth directed, which would presumably be inconsistent with a thermal cause. This is not so: quite the contrary, since the spin axis and the Earth direction mostly coincide, an Earth directed anomaly is exactly what one would expect to see in case of a thermal cause. Second, I don’t think it is even relevant to say that “a new physics cause may still be possible”. Of course new physics is always possible. But before one can speculate about new physics, “old physics” must be excluded, i.e., there must be an incontrovertible demonstration that conventional physics cannot account for the observed phenomena. This is not the case for the Pioneer anomaly: conventional physics comfortably accounts for the anomalous acceleration. Sure, there are small discrepancies that are within the margin of error, but you don’t fish for new physics within the margine of error. That’s not the way science is supposed to work.

After another 550 km drive at the end of an already very long day, I finally made it home late last night, concluding a very productive 3-day visit at the Perimeter Institute.

While there, I gave another talk on the Pioneer anomaly. I felt that it went well and as far as I can tell, it was very well received.

All in all, it was time well spent.