Thread: Law of gravity incomplete

Found this interesting article. Apparently for objects the size of spacecraft there is a small, but non 0, and consistent, deviation from trajectories expected with present gravitational equations. In effect gravity seems stronger for a smaller object (spacecraft) than for a larger object (planet). The effect has been observed with a handful of recent spacecraft, plus the voyagers.

Discuss.

Originally Posted by Numsgil

Found this interesting article. Apparently for objects the size of spacecraft there is a small, but non 0, and consistent, deviation from trajectories expected with present gravitational equations. In effect gravity seems stronger for a smaller object (spacecraft) than for a larger object (planet). The effect has been observed with a handful of recent spacecraft, plus the voyagers.

Discuss.

That issue has been on the table for a while. However, I am not sure whether or not the measured deviations from predictions are continuing to hold up. Have you seen an references of a more recent nature?

Well it talks about the gravity assist from the Rosetta mission, which is a modern ESA mission, so it hasn't been ruled a fluke of older designs or anything like that. Apparently it's still an observed phenomena, still seems fairly predictable in its deviation, and still entirely unexplainable.

Many explanations have been put forward. It reaches from very trivial causes to highly speculative theories about a modified gravitational law, e.g. in the framework of MOND and TeVeS theory. In fact, the perturbations are that small, that even a tiny asymmetry in the self-radiation of the spacecrafts could be responsible for the additional acceleration (photon momentum).

A link to a PDF document with serious physics behind it is this one:
http://arxiv.org/PS_cache/gr-qc/pdf/0604/0604052v1.pdf

I hadn't thought of dark matter and energy as also being symptomatic for the need for a new physics.

I wonder if the next paradigm shift will make physics more confusing or less confusing.

Originally Posted by Numsgil

I hadn't thought of dark matter and energy as also being symptomatic for the need for a new physics.

I wonder if the next paradigm shift will make physics more confusing or less confusing.

Dark matter may or may not require new physics. There is a good chance that it may.

Dark energy almost certainly will require something new. Even if a positive cosmological constant provides a good model, a reason for that constant is needed. The zero point energy of the quantum vacuum can explain a postiive constant, but the current calculations overpredict the magnitude by about 120 orders of magnitude. That is a really big error.