The Pioneer Anomaly Options

[remcook]

http://www.planetary.org/news/2005/pioneer_anomaly_faq.html

The planetary society may be checking it out...

The Planetary Society has committed to raise the funds to preserve the priceless Pioneer data from destruction.


After years of analysis, but without a final conclusion, NASA, astonishingly, gave up trying to solve the "Pioneer Anomaly" and provided no funds to analyze the data. The Pioneer data exists on a few hundred ancient 7- and 9-track magnetic tapes, which can only be read on "antique" outdated computers. The agency is going to scrap, literally demolish, the only computers able to access and process that data in the next few months!

[Mongo]

So this team has observed a cloud of neutral hydrogen with an estimated mass of 100 million suns, which has a much too large rotational velocity for its mass. This is the logical end point of the trend from high-surface-brightness elliptical galaxies, which have only slightly too large rotational velocitys, through normal spiral galazies, which have larger excess rotational velocitys, through low-surface-brightness galaxies, which have extreme excess rotational velocities, and finally this lowest-surface-brightness galaxy (which is what this object really is), which has the highest excess rotational velocity of all.

Looks like a trend to me.

I fail to see that this proves that dark matter exists, since the same MOND-like physics (which apparently describe full General Relativity) that were postulated to explain other cases would presumably apply to this object as well. The whole point of MOND-like theories is that they apply under conditions of galactic distances but low gravitational acceleration, which is why the difference between Newtonian models and observation increases with declining surface brightness (which tracks mass and hence gravitational acceleration). Something like this gas cloud would be expected to have remarkably high rotational velocitys.

I think that we should wait to see from a refereed paper if this object is explainable under MOND or GR before proclaiming that dark matter exists.

Bill

[The Messenger]

I think that we should wait to see from a refereed paper if this object is explainable under MOND or GR before proclaiming that dark matter exists.

Bill

I think we better wait longer that that - there are many refereed papers that all-but-insist Dark Matter is a done deal. Sorry - I don't believe in the Easter Bunny, and I don't believe theories that cannot be demonstrated using local observables and principles are scientifically valid.

There has been an intense campaign in the last four decades to identify the baryons responsible for altering galactic rotations, and these careful seaches have turned up naughta. Most of the conjecture I have seen about why these searches have failed; and how Dark Matter can best be explained have involved hypotheses that simply cannot be tested - and yes, this includes redistributing galactic masses so that General Relativity fits the bill.

The Pioneer anomalies are observational events that we can sink our teeth into. This is where the trail should be picked up - in our own backyard. This is where we can either support or null a hypothesis.