In Newtons universal law of gravitation any two masses attract each other according the inverse square law of distance.
In our local planetary environment there seems to be no
evidence of any other behaviour than this.
Yet at very long distances any two astronomical objects are
separating from each other according to the Hubble law, even at an accelerating rate.
Thus there is something like a local group of planets or whatever that behave normally, whithin a space that is continually expanding.
Would like to know, especially from astronomers, where and at what distance this behaviour changes, and also if it is really true that at local distances there is no evidence for the expansión process, given that it would be a small effect.
Please let me know if these references/sites are helpful to you:
1. Stability of Colloidal Suspensions
https://www.ethz.ch/content/dam/ethz/special-interest/chab/icb/.../Chapter6.pdfCached
The charges on the particle surface provide an energy barrier to be overcome ... The interaction between two bodies is dominated by two forces, an attractive van der Waals .... of Hamaker constant implies that van der Waals interactions are repulsive. ... The ions are free to diffuse and are influenced by the local electrostatic
2. Gravity-Induced Flocculation o~or - CiteSeerX
citeseerx.ist.psu.edu/viewdoc/download?
doi=10.1.1.619.4193&rep=rep1...pdfCached
by DH MELIK - 1984 - Cited by 62 - Related articles
electrostatic repulsion, the gravity-induced flocculation rate is approximately proportional to gO.8O (where g is the local acceleration of gravity) and not g as previously predicted. ... differential creaming rates between large and ... der Waal attractive and electric double layer ..... to reduce the potential barrier so primary.
3. Sedimentation of aggregating colloids - Computational Soft Matter Lab
csml.northwestern.edu/resources/Reprints/jcp5.pdfCached
by JK Whitmer - 2011 - Cited by 14 - Related articles
We investigate the combined effects of gravity, attractive interactions, and Brownian motion in sus- ... tinuously increasing the attraction strength between colloids ..... ulations both with and without this barrier by setting A = 1 ..... as a function of local colloid volume fraction φ) for attractive particle sediments obtained by ...
Dennis
Dennis Mazur
Within the Newton theory it exists no barrier, but a very usefull concept exists, it is the Kepler radius of an overdensity (in an empty universe). But within general relativity a barrier exists for some models for the universe, as for example all the de Sitter models. You have 2 names for this barrier : the "turnover radius" and the "attraction radius"; I prefer this last name. But it is very difficult to observe this radius, so astronomers give the Kepler radius. For the general relativist "attraction radius", for the local group of galaxies this radius is between 1 and 1.5 Mpc; for the Milky Way I don't know, perhaps 300 kpc, 500 kpc, 800 kpc ? The dynamic is not well known. Behind we have the M_i=M_g problem or the Mach hypothesis.
Michel Mizony, ICJ université de Lyon
Clusters of galaxies are bound, superclusters will probably break up. That's gives you a rough feel for the answer but there is no definite number because the Hubble Law is a simple figure common everywhere while the attractive behaviour locally depends on the masses and separations.
Dear Mrs. Weisz, thanks for your recommendation.
All this summer I work on the subject of dark matter and dark energy; this two (false) concepts are important about the attraction radius ( or "turnaround" and not "turnover" as I write in my first mail). I can send you preprint, if you want, but it is very difficult to understand if you don't know many mathematics).
best regards
Michel Mizony
The nature of gravitation depends on properties of substance of gravitating bodies. I believe, there exist different kind of gravitation in the Universe, not only the force of attraction in Newton's theory. For example, the force of attraction converses to the force of repulsion in the model of the sphere, consisting from ideal liquid, by the condition that the liquid transforms to physical vacuum. The barrier is the relation between the radius of the object and its density: if the relation is not realized, the barrier exists.
Larissa
do not understand very well
one is a language problem
converges or changes instead of converses? to converse is to talk.
do no understand the relation of liquid to vacuum or the
relation radius to density .
can you explain better?
regards , juan
Michel,
could not find kepler radius or over density on google yet.
Is this some sort of singularity?
one thing I am understanding now is that the transition depends on the
conditions, galaxy, or local group, etc.
can you give a short explanation or a reference for over density for example?
Yes, I prefer physical explanations to long math. For example a density too high
in an empty universe sounds contradictory.
by the way I am a Mr.
regards, juan (john in english)
Yes, you are right Mr. Weisz
overdensity in one word, search for example "Milky Way, overdensity"
For a radius for a galaxy, by analogy with Kepler's law, we have to search
Keplerian rotation curves.
Exguse me for my bad english
Michel Mizony
From what I understand so far is this question is far from being esily or well answerable so far; even start to hear that even GR wont work out so well due to dark matter etc.
So I will still hold out my original question in simplest form, in hope of advancements.
It is true that within Newtonian theory one could, depending on mass,etc,
estimate some realistic radius before the attraction becomes too small,
but this is not consistent with some new theory taking over beyond some given distance, as expected from Hubble expansion. Then slight reltivistic corrections
to Newton could also be factored in.