Category Archives: Science/Medicine

Confirmation of what I always believed: fly a plane, catch a cold. Of course, this year I have managed to have a nasty one without going anywhere.

(Spotted via SFDB.)

I was sorry to learn that there is likely a very rational explanation for the Pioneer anomaly, the 30-year mysterious deceleration of the Pioneer spacecraft once it got out of the solar system, a mystery much loved by science fiction readers. I would have liked the mystery even better if there had been an unexplained acceleration, but you can’t have everything.

It seems that no singularities are involved after all, and that gravity doesn’t get stronger or weaker at long distances either. Heat ‘Most Likely Cause’ of Pioneer Anomaly:

A number of possible explanations have been proposed over the ensuing decades, including the possibility that gravity behaves differently at such large distances from earth — thereby requiring a modification of gravitational theory.

But over the last couple of years, evidence has been pointing more strongly to heat as the most likely culprit. Specifically, heat from the plutonium inside the spacecraft’s generators, some of which got converted into electricity while the rest of it radiated into space. If it did so unevenly, radiating more heat in one direction than in another — only a 5 percent difference is required — that might be sufficient to give rise to the Pioneer anomaly.

Found via Slashdot.

httpv://youtu.be/xhCY-3XnqS0

One of my favorite scientific anomalies — why spacecraft speed up at the edge of the solar system — may have been explained.

For quite some time, the physics community has been baffled by subtle anomalies in the trajectories of the Pioneer 10 and 11 spacecraft. If no “mundane” effect (e.g. propulsion from a gas leak, or radiation pressure, or collisions with space dust) can be found to explain it, then serious questions would have to be asked about whether our understanding of gravity is incomplete. This paper, however, claims to explain the anomalous acceleration in terms of thermal radiation.

Source: Unqualified Offerings, Mean scientists say no gravitational anomaly in outer solar system, referring to Modelling the reflective thermal contribution to the acceleration of the Pioneer spacecraft.

My only remaining hope that there might actually be a singularity is the date of the paper.