Search continues for a non-creationist solution to the ‘Pioneer anomaly’


Photo NASA
Artist’s view of Pioneer 10 above and far beyond the Solar System.

For ten years, about once a week,1 papers have been appearing in the scientific world offering new solutions to the ‘Pioneer anomaly’, a small but mysterious slowdown of four outward-bound spacecraft: Galileo, Ulysses, and Pioneers 10 and 11.

Some papers seek for a mundane cause, such as heat radiation emitted by all three types of spacecraft in exactly the right direction at exactly the right intensity … the required coincidences stretch my credulity a bit. A recent talk at a scientific conference2 reported that such an effect ‘could account for at least a third of Pioneer 11’s anomalous acceleration.’ [Note that ‘acceleration’ to physicists also includes slowing down or a change in direction.] Why isn’t there more certainty, what about the other two-thirds, and what about the other three spacecraft? It doesn’t look like celebrations are yet in order.

Many other papers invent exotic physical laws to explain the anomaly, especially why the amount of slowdown is very close to a number that has cosmological connections. The very existence of so many different theories shows that their authors are not satisfied with either the mundane explanations or the other exotic theories.

A few papers use the physical laws we know about, but invoke new conditions that would give new results, such as imagining much more mass in the as-yet-unobserved Oort cloud that is supposed to be far beyond the orbit of Pluto occasionally supplying new comets to the Solar System. The conditions required for such explanations appear to be not credible, judging by the lack of enthusiasm for them in secular science circles.

Last fall I offered a solution of the third type in the Journal of Creation.3 It uses standard physics, such as Einstein’s general theory of relativity, and makes standard assumptions, such as the expansion of space (to which Scripture alludes4).

The only non-standard condition I used was to assume that the matter of the cosmos is limited in extent, with a fair amount of empty space beyond the matter, an assumption that is supported by the Bible. With those relatively modest beginnings, I was able to explain the Pioneer anomaly. In fact, this anomalous apparent acceleration of the Pioneer spacecraft could be the first local manifestation we have observed of the expansion of the cosmos, and the first evidence that expansion is occurring in the present, not just the past.

The assumption I used violently contradicts the foundational assumption of the Big Bang, which says the universe has no centre and no edge. In other words, it does not have a portion of empty space around its matter. Consequently the Big Bang model has been unable to explain the anomalous Pioneer acceleration.

My paper does not appear to have slowed the flow of new theories. In fact, the flow seems to have increased, and (perhaps it is only my imagination) the theories seem to have become wilder and more desperate. Yet for those people who prefer a biblical view of the cosmos, it looks like my article offers a reasonable explanation. Perhaps other creation cosmologists will offer other biblical options.

Published: 7 May 2008


  1. For example, using Google Scholar to search for the phrase ‘Pioneer anomaly’ occurring only in 2008 turned up nearly two dozen papers by April, most of which were trying to explain the effect. Return to text.
  2. Turyshev, Slava G., Pioneer anomaly: status of new investigation, American Physical Society meeting, April 11–15, St. Louis, Missouri, Abstract H7.00001, given 13 April 8:30 AM. As reported by Stuart Goldman, ‘Pioneer Anomaly’ solved? Sky and Telescope Homepage News. Return to text.
  3. Humphreys, D.R., Creationist cosmologies explain the anomalous acceleration of Pioneer spacecraft, Journal of Creation 21(2):61–70, August 2007; non-technical article, Humphreys, D.R., Creation cosmologies solve spacecraft mystery, Acts & Facts 36(10):10–12, October 2007. Return to text.
  4. There are 8 references in the Bible that God ‘stretched out the heavens’: Job 9:8; Isaiah 42:5, 44:24, 45:12, 51:13; Jeremiah 10:12, 51:15; Zechariah 12:1. Return to text.

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