How Does the Solar System's Angular Velocity Change Over Time?

[twofish-quant]

Maybe some other guy at a later time would read this, and could be interested in doing all the number crunching.

My guess is that lots of people have already crunched the numbers, and they haven't found anything. If you crunch the numbers and you find something then you publish, but if you do it and you end up with nothing then you have nothing to publish.

I want to stress that when I mentioned "dark matter", I was talking about an actually unknown or undiscovered aspect of the way gravity(or another force, btw) works, not about a dark companion/black hole. That is, I understand "dark matter" as a way to say that we don't know what gravity is, and even how gravity works at long scales.

At large scales. People who do modified gravity theory put into their models the idea that at solar system scales, nothing the propose makes a difference. That's the idea behind f(R) and MOND models. All of them are set up so that at solar system scales, there is nothing weird, because if there were something really weird we would have noticed it. Yes there is an anomaly of a few mm each year, but there is no anomaly that is a few cm per year, and that puts huge limits on what you can get away with.

About centripetal acceleration. It looks like from the numbers that if we are just a bit more accurate about our measurements then we should be able to see some effects from galactic rotation. Also, if you

It could be interesting to analize this centripetal acceleration and its potential relation with the movement towards the Solar Apex, i.e. the movement towards the solar apex as a consequence of a wobbling or oscillation around the main direction of rotation. Picture the Sun and the solar system in a kind of circular(spiral, really) stream (the milky way arm in which are located), oscillating back and forth and up and down while they travel around the center of the galaxy.

This is likely to be what's going on. One thing that would be interesting to look at is to look at models of the suns motion through the spiral galaxy. and see what accelerations there are.

This would clearly talk about the galaxy as some kind of "sinking hole", and of gravity as a fluid. Maybe the gravity we know, that is, the gravity we tend to associate with matter, is only a part of the total phenomena, and there's another aspect of gravity that is not associated with matter(what we call "dark marker"), and which only manifests itself as a flow affecting the matter we can observe.

One thing that about dark matter is that there are a lot of different types of dark matter. Most of the ordinary matter in the universe is dark, and that would certainly have some effect on galactic motion.

 

[maurol2]

My guess is that lots of people have already crunched the numbers, and they haven't found anything. If you crunch the numbers and you find something then you publish, but if you do it and you end up with nothing then you have nothing to publish.

Hi twofish-quant.
I'm not so sure about that. These anomalies are relatively recent.
And Iorio in fact did discovered something related to the retrograde perihelion of Saturn. Namely, that it could be explained by a mass outside the solar system, and (perhaps more importantly) if the mass is in the direction of the galactic center, their results are also consistent with MOND.

At large scales. People who do modified gravity theory put into their models the idea that at solar system scales, nothing the propose makes a difference. That's the idea behind f(R) and MOND models. All of them are set up so that at solar system scales, there is nothing weird, because if there were something really weird we would have noticed it. Yes there is an anomaly of a few mm each year, but there is no anomaly that is a few cm per year, and that puts huge limits on what you can get away with.

Again, Iorio apparently explained the anomalous motion of the perihelion of Saturn. This is a tiny effect(and is even yet to be confirmed) and the math is hard, but anyways, the effort loks very worthwhile.

One thing that about dark matter is that there are a lot of different types of dark matter. Most of the ordinary matter in the universe is dark, and that would certainly have some effect on galactic motion.

Dark matter could be not ordinary matter, but something else that we're only expecting to be ordinary matter, due to conceptual constraints.
In my opinion, it's necessary to disassociate gravity from ordinary matter(at least as an avenue for research), to (perhaps) be able to understand what's really going on.
Accumulation and acceleration of matter would then be a consequence of gravity, but gravity would not be a consequence of matter(which is also a logical dead-end, btw).
That is: accumulation/acceleration of matter is a manifestation of gravity, but there could be "gravity"(or something that behaves like gravity) without matter as a cause.
We tend to associate gravity with matter only because we're used to see gravity where there is matter, but, as you said before: most of the "matter" of the universe would not be ordinary matter. This is (at least potentially) equivalent as saying that there exists gravity without a material cause.

 

[Old Smuggler]

All of them are set up so that at solar system scales, there is nothing weird, because if there were something really weird we would have noticed it. Yes there is an anomaly of a few mm each year, but there is no anomaly that is a few cm per year, and that puts huge limits on what you can get away with.

You forgot the observed secular increase of the AU, inferred to be about 15 cm/yr.

But in general, your line of reasoning is not valid. That is, taking the mainstream model and trying to restrict
alternatives solely from the fact that the remaining anomalies are small, is not a useful exercise. There are
two main reasons for this. First, almost all observational results in astrophysics are indirect, i.e., the raw
data are analysed with some (mainstream) theoretical assumptions assumed to be valid. The numbers
thus obtained and cited as observational facts, are not completely general results, but inferred and theory-
dependent results. That is, change the theory and the numbers may change. This effect must be evaluated
from case to case - no general statements of how any alternative theory affects the results can be made.
Second, mainstream theory includes free parameters, some of which may absorb large effects predicted
from alternative theories. Unfortunately, it's a problem that free parameters may sometimes be treated as
independent facts, blocking the possibility that free parameters can be disposed of and replaced with
something else in an alternative theory.

The bottom line is that a little learning is indeed dangerous. That is, one should certainly study the
mainstream models thoroughly, so that one knows what theoretical assumptions are made when
analysing the data - just to get an idea of how general the results are. But one should also study alternative
models where crucial mainstream assumptions do not hold. Only by doing this can one really get an
impression of the size of effects one may get away with and still being consistent with observations.
If you do this, I believe that you would be surprised.