The Newtonian model, with some empirically determined fudge terms added for extreme cases such as Mercury's perihelion advance rate, is still a useful tool for practical calculations of planetary orbits.
You flat out said that Newtonian Mechanics (actually gravity) should have been thrown out, which is ridiculous. It only needs to be extended, or generalized, to work in regions where it fails. Which is what GR does. But Newtonian Gravity is just fine for everything else in the solar system.
I also get tired of Jerry's constant appeal to "epicycles". Any new terms added and treated as perturbations to Newtonian celestial mechanics are not abitrary parameters chosen to fit the data, but actually depend on orbital elements and masses already known and measured. All current ephemerides such as those from JPL take GR into account, and guess what? -- the ephemerides work.
I'm beginning to think that maybe I should assess penalties for gratuitous use of the word epicycles just as I do for gratuitous use of the phrase "paradigm shift". How many points should it be? Five or ten?
Barbarians at the Horizon
Many of the earlier theorists including Einstein sought logic in Nature and developed ideas that appealed to an aesthetic. They looked for both simplicity and beauty in their ultimate expressions. GR is no exception. As Friedmann first noted, the equations are naturally dynamic leading to either expansion or contraction and the Lambda was considered and ultimately rejected by Einstein as an aesthetic violation to its dynamic nature or a “great blunder”.
While the observations attributed to the dark sectors can not be denied, is it correct to incorporate their effects into the “canvass” that GR is “painted” upon?
Would it be correct to assert that DaVinci did not appreciate saints and proceed to add a “halo” about the head of the Mona Lisa and then add a Lambda shaped moustache to express accelerated aging?
Would it be correct to assert that Beethoven took his “Fate Knocking at the Door” motif opening his 5th symphony too seriously and proceed to scrape off the three flats of the key signature to create a lighter “halo” suggestive of bellowing laughter of a jolly giant, and then append to the Allegro con brio tempo a “ma poco a poco accelerando quasi Lambda”?
Einstein is not here to defend the aesthetic integrity of his work any more than DaVinci or Beethoven. While it may seem temporarily expedient to incorporate the LCDM on top of GR, into its “canvass” as it were, it detracts from its original aesthetic quality. As these myopic crutches become more entrenched and mar the original beauty, possible failures of the additions might be errantly also associated with the original theory which did not incorporate them and improperly suggest the original theory might be at fault as well.
Furthermore, as the LCDM blemish continues over time to be associated with GR leading to a GR + LCDM paradigm on the same canvass, the searching for their own aesthetic “canvass” for each of separately Lambda and separately CDM is less considered.
Not all unifications are beautiful.
Notice that I am not sure.
There is little variability from where we sit: On the surface of the earth, plane geometry dominates, so an inverse square law works very well.
As for the rest of the solar system, (and indeed the rest of the galaxy), there are puzzles that resist solutions - everything from the mascons of the moon to the core composition of comets. There are some interesting observations here:
http://arxiv.org/abs/1109.0266 Mercury and frame-dragging in light of the MESSENGER flybys: conflict with general relativity, poor knowledge of the physical properties of the Sun, data reduction artifact, or still insufficient observations?
From the abstract:
In other words, taken at face value, there is no measurable Lense-Thirring effect and the General Relativistic prediction is falsified. Iorio's take on this if found in a subsequent paragraph:Originally Posted by Iorio
(my bold)Originally Posted by Iorio
So is it the Lense-Thirring effect that is not being realized, or have we really screwed up in our estimates of the solar angular momentum? (Which would really throw off the predicted degree of relativistic gravitational lensing.)
Or, as Iorio further speculates:
Actually, in principle; if you have to throw in major unanticipated 'gravitomagnetic' effects that cancel the expected motions, nobody has game. I can just as reasonably speculate that both the unanticipated gravitomagnetic effects and the Lense-Thirring effects are null; and everything we see that does not agree with Newton is simply because Newton never gave us true causality in the first place: He gave us a set of equations that work near the earth. But we must prove, without broad prior assumptions, that they work elsewhere.Originally Posted by Iorio
Right now, Messenger scientists are trying to make sense out of the extraordinary gravity fields they are observing. (I don't think they can!) On Earth, gravitational scientists are pouring over data; looking for the slightest glimmer of a gravitational wave, and LHC scientists are trying to draw lines between the latest round of experiments and what they are observing. What they all have in common, is that they are not seeing what they anticipated. Far from being ridiculous, Newton's fundamental assumptions can and should be challenged.
Last edited by Jerry; 2012-Apr-02 at 04:36 AM.
Most of the time; the corrections applied are experimental errors - interference from neighboring circuits; or electron clouds or cascading breakdowns; but once in a while a new and unpredicted phenomenon pops up - such as the Hall effect.
It takes time and patience to determine if the another knob is needed or another theory. If adding another knob improves the predictive power, it is sometimes the correct solution. (Sometimes a small planet just drifts into the picture and gets blamed for causing the problem.)
Noted. Knobs it is!I also get tired of Jerry's constant appeal to "epicycles". Any new terms added and treated as perturbations to Newtonian celestial mechanics are not abitrary parameters chosen to fit the data, but actually depend on orbital elements and masses already known and measured. All current ephemerides such as those from JPL take GR into account, and guess what? -- the ephemerides work.
My bold. Shouldn't you be saying Einstein here? We all know that Einstein's GR outperforms Newton's simple theory in extreme cases and thus has superseded it.On Earth, gravitational scientists are pouring over data; looking for the slightest glimmer of a gravitational wave, and LHC scientists are trying to draw lines between the latest round of experiments and what they are observing. What they all have in common, is that they are not seeing what they anticipated. Far from being ridiculous, Newton's fundamental assumptions can and should be challenged.
Still no signal detection and constraints on the energy of potential signals improved.
Press release from NASA:
A model-independent analysis of the Fermi Large Area Telescope gamma-ray data from the Milky Way dwarf galaxies and halo to constrain dark matter scenarios
It is nice, but not necessarily correct. It bumps against planet formation theory and is very curious. Basins are showing gravity anomalies of up to 100 mgal. That is unreal. http://www.lpi.usra.edu/meetings/lps...df/sess401.pdfOriginally Posted by MIT
Then there is this:Originally Posted by MIT
By the way, I didn't know these articles were out there until I went looking for them. I knew the gravity fields would be difficult-to-impossible to model because they have been for every other moon and planet: I expected unreal gravity field solutions because Newtonian rules are not really working anywhere.Originally Posted by Europlanet
Here are the session papers: http://www.lpi.usra.edu/meetings/lps...df/sess401.pdf
The current solutions are not well constrained- there is significant uncertainy due to the solar wind and radiation pressure.
Nope. Einstein buffered the errors in the Newtonian solution by redefining space and time. It is a curious solution; because it says the non-Newtonian results are spacial and not caused by any active force. It also means that when the bent-space solution does not work; non-baryonic matter is required. This is an iffy solution - can I use unobtainium?Originally Posted by Hornblower
Last edited by Jerry; 2012-Apr-08 at 08:08 PM. Reason: Added Session Paper reference.
Here are the session papers: http://www.lpi.usra.edu/meetings/lps...df/sess401.pdf
The first year of Messenger orbital data has created many more mysteries than it has resolved. First, the libation and core-to-crust solution requires a eggshell-thin crust over a heavy (liquid)mantle with perhaps a solid core. A thin crust should mean mascons of the denser materials percolating through the bottom of craters, such as we have identified on the moon. But there is a snag on mercury: while some mascons may exist, the composition, so far, is similar to the surface composition; a low-Iron crust that is high in sulfur. The one possible exception is the Calois impact basin; which has a center that has risen above the creater rim, and displays a positive anomaly of greater than 100Mgal.
There are several problems with this solution: in order to lift a large heavy mass in the center of a crater higher than the rim; there should also be displacement of the rim - the thin crust should have trouble supporting such an upswell without more displacement in the over all crater structure.
So there are challenges in the composition and topography that make the current solution difficult to model, not to mention the problem with the core not cooling enough in the time frame Mercury has been getting pummelled with rocks to solidify the outer core.
Mercury is going to be hard nut to crack, and as I said, It is a major challenge to model Mercury using known physics.
Then why have you just presented Mercury as an example? Surely something this dramatic you should be able to easily find dozens of papers covering just about every mission out there?By the way, I didn't know these articles were out there until I went looking for them. I knew the gravity fields would be difficult-to-impossible to model because they have been for every other moon and planet: I expected unreal gravity field solutions because Newtonian rules are not really working anywhere.
Jerry DO not post ATM ideas outside the ATM Forum. You know this and we have seen your 'alternative' ideas on gravity before, keep them out of mainstream threads.
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But I'm not interested in another sensational theory of gravity.
He could only point out what he meant, without going into details.
Jerry, per yours above: The Lense-Thirring effect (some think it should be called, per GR, the Einstein-Thirring-Lense effect) can very easily be described with the Sun's angular momentum and its inverse square law application to Mercury's perihelion period (when its spin coincides with its orbital velocity, so appears to stop), as I had done in this simple calculation, FYI: (Sept. 1, 2006) http://www.humancafe.com/discus/mess....html#POST1733
It works out rather neat, though crude. Einstein's GR had more elegant finesse.
Last edited by nutant gene 71; 2012-Apr-15 at 08:56 PM.