Friday, December 14, 2007

News From Saturn


This week more news comes from Saturn's Rings. Perhaps humans are drawn to their beauty for a reason. They could hold secrets to how our planets formed, and may even point to future sources of energy. In the December issue of Nature scientists report discovery of an enormous ring current surrounding Saturn. Most of the plasma comes from the south pole of Enceladus. The clump of charged particles rotating in sync with Saturn is still considered a mystery. Charged particles circling the planet every 10 hours 47 minutes are like those that would be produced by an orbiting Black Hole.

Wednesday at AGU, Cassini scientists claimed that Saturn's Rings are nearly old as the Solar System. Previously it was thought that the Rings would decay within 100 million years. We would then face the anthropic question of why the Rings exist in just the right time for humans to enjoy them. Later I had the good fortune to talk with Larry Esposito, who wrote the book on Ring observations. He believes the Rings are continually replenished and recycled by icy moonlets orbiting within. These unseen bodies are held together in spite of Roche's Limit by colliding and melting into each other. Normally bodies colliding at orbital velocities should not stick together. Perhaps something else is needed to seed their formation.

Friday C.D. Murray talked about F Ring objects and embedded moonlets. The "fans" in this Ring are evidence of embedded objects. The shepherd moon Prometheus has been observed to interact with F Ring, sometimes leaving strands or jets of materiel. The "jets" are interpreted as resulting from collisions. A big question remains why F Ring precesses in the first place. The Rings would be another place to look for a Black Holes.

Afterward M. Sremcevic talked about Propellor features in the Rings. These are located in a narrow 3000 km belt at 130,000 km from Saturn. The objects that cause the propellors must be very small, for anything bigger than 1 km would open a gap in the Rings. Their behaviour is incompatible with an accretion origin, so they are considered as possible fragments of a shattered moon. I asked and Sremcevic confirmed that his computer models treated the objects as point masses (like Black Holes).

Many, many mysteries remain about the Rings. Some of these mysteries would be explained by very tiny but massive objects hidden within. Thes objects would also give off radiation, like the clump of charged particles. Saturn's rings show conditions similiar to those which formed our Solar System. Perhaps Black Holes are closer than we think.

For more news, check out the new Carnival of Space!

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3 Comments:

Blogger Matti Pitkanen said...

For century ago the problem was why the electron in hydrogen atom does not fall into nucleus. Now one of the many problems is why Saturn's rings do not disappear if few hundred million years.

Dark matter with a gigantic gravitational Planck constant around which the visible matter condenses would be the solution to the problems but the time is of course not ripe for this idea since we are still in the state of knowing. We know that Planck constant can be put equal to 1 with a suitable choice of units; we know that quantum effects are not important above molecular length scales; we know that physics is fully understood above intermediate boson length scale apart from effects due to "complexity" and that the rest is about details in much shorter length scales. And of course, already 23 years we have already had the only possible quantum theory of gravitation! Have anyone heard of a string theorist showing interest on Saturn's rings!

The defenders of the old theory are so well informed that they will give up only after theory is so full of holes that there is nothing to defend anymore.

6:26 PM  
Blogger alex kaplan said...

Happy Christmass,Louise

5:58 AM  
Blogger nige said...

"For century ago the problem was why the electron in hydrogen atom does not fall into nucleus." - Matti

It was only 94 years ago when that question was first asked!

Ernest Rutherford wrote on 20 March 1913 the following question to Niels Bohr in a letter after Bohr (on 6 March, 1913) had sent Rutherford his paper on electron orbits (Rutherford had acquired evidence for nuclear structure from the backscatter of alpha particles hitting hold foil which had been measured by Geiger and Marden, but he was critical of Bohr's extension to his model):

"There appears to me one grave difficulty in your hypothesis which I have no doubt you fully realize [conveniently not mentioned in your paper], namely, how does an electron decide with what frequency it is going to vibrate at when it passes from one stationary state to another? It seems to me that you would have to assume that the electron knows beforehand where it is going to stop."

[Quoted by Abraham Pais, "Inward Bound: Of Matter and Forces in the Physical World", 1985, page 212. I've added emphasis in bold.]

This conflicts of quantum theory with classical physics had tragic consequences; Bohr just became paranoid/dictatorial and said it was nobody should be allowed to question his work in that manner, so attention moved away from contradictions.

The resolution to this is that electromagnetic forces are caused by the exchange of gauge bosons like virtual photons between charges. These exchange radiations are only observed as forces because there is a match between the flux of radiation going each way ("real photons" are detectable because they only go one way, so they produce net oscillations of electrons, etc., revealing their presence by inducing electric currents and so on). When an electron which is radiating reaches its "ground state" it is merely reaching such a position that it is in an equilibrium whereby the rate it receives virtual photon radiation is matched by the rate it radiates virtual photon radiation.

The work of Professors Rueda and Haisch contains errors of detail as pointed out by John Baez at http://groups.google.com/group/sci.physics.research/msg/c8777dd9b81f1b7f, but it is useful in making a first effort to tackle the idea that radiation exchange in quantum field theory, which is continuing at all times in the vacuum, causes inertia and gravitation in some way:

Bernard Haisch and Alfonso Rueda, "Contribution to inertial mass by reaction of the vacuum to accelerated motion", Foundations of Physics, v28, 1998, pp1057-1108, http://arxiv.org/abs/physics/9802030

Bernard Haisch, Alfonso Rueda, and York Dobyns, "Inertial mass and the quantum vacuum fields", Annalen der Physik, v10, 2001, pp393-414, http://arxiv.org/abs/gr-qc/0009036

Bernard Haisch and Alfonso Rueda, "Gravity and the Quantum Vacuum Inertia Hypothesis", Annalen der Physik, v14, 2005, pp479-498, http://arxiv.org/abs/gr-qc/0504061

Haisch has a lot more articles (with responses to critics included) on http://calphysics.org/. He summarises his outlook there: "Advances are made by answering questions. Discoveries are made by questioning answers."

(See also a longer list of online work at http://www.calphysics.org/sci_articles.html.)

I've included this topic (in a general way) in a blog post here. By the way, electrons do "fall into the nucleus" in the case of radioactive decay by electron capture (where the decay occurs by the capture of an inner orbital electron by the nucleus!):

"Electron capture ... is a decay mode for isotopes that will occur when there are too many protons in the nucleus of an atom and insufficient energy to emit a positron; however, it continues to be a viable decay mode for radioactive isotopes that can decay by positron emission. If the energy difference between the parent atom and the daughter atom is less than 1.022 MeV, positron emission is forbidden and electron capture is the sole decay mode. For example, Rubidium-83 will decay to Krypton-83 solely by electron capture (the energy difference is about 0.9 MeV).

"In this case, one of the orbital electrons, usually from the K or L electron shell (K-electron capture, also K-capture, or L-electron capture, L-capture), is captured by a proton in the nucleus, forming a neutron and a neutrino. Since the proton is changed to a neutron, the number of neutrons increases by 1, the number of protons decreases by 1, and the atomic mass number remains unchanged. By changing the number of protons, electron capture transforms the nuclide into a new element. The atom moves into an excited state with the inner shell missing an electron."

- http://en.wikipedia.org/wiki/Electron_capture

6:08 AM  

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