Vinicio Coletti's proposal about gravity

Does it depends on speed?

Missing matter is really missing?

First published on December 12, 1999
following a newsgroup discussion on July, 1998
Updated on October 30, 2002

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According to Newton, the gravitational force depends on the mass of the two bodies we are considering and on their distance:
F = G m1  m2
--------
d2

The G in the formula is the gravitational constant, expressing a scale factor, that depends also on the units you use. Standard units are the meter and the kilogram, thus

G = 6.67259 x 10E-11

This mean that between two bodies of 1 kg each at a distance of 1 meter there will be a gravitational force of about 66.7 pN (pico-Newton).
According to Einstein, gravity is not a force at all. Bodies curve space-time and they move along this deformed continuum. Also, the way we perceive phenomena depends on the relative motion of the bodies, if they are accelerated or not and so on.
If a body is going away from an observer at rest, at a very high speed (a not minimal fraction of the speed of light), signals from it will still come at the speed of light, but shifted to lower frequencies.
All phisical phenomena we observe on the fast body will look slower than normal (and for us they will be actually slower).
The dimensions of the body will also look shorter from the farest to the nearest side and, most importantly, the mass will look greater.

My proposal

During July 1998 I discussed these topics on an Italian newsgroup, namely it.scienza, asking questions to some scientists and other people discussing there.
In one of these messages I asked this question:
if we perceive red-shifted radiation from a body going away very quickly, and this is a quite real effect (we see it!), why we should not perceive the effects of its greater mass, which is also a relativistic effect?
Well, the question was indeed asked a bit more naively, as you can read in one of the original messages posted by me on the newsgroup it.scienza on July 2, 1998 (other messages are lost).
However, this time I had no answers...
The message is in its original form, in Italian, but I have outlined in bold the most important sentence.

Path: news.mclink.it!usenet
From: vcoletti@webcom.com (Vinicio Coletti)
Newsgroups: it.scienza
Subject: Massa
Date: Thu, 02 Jul 1998 05:45:44 GMT
Organization: MC-link The World On Line
Lines: 22
Message-ID: <359b1d5e.28599899@news.mclink.it>
Reply-To: vcoletti@webcom.com
NNTP-Posting-Host: net144-105.mclink.it
X-Newsreader: Forte Free Agent 1.1/32.230
 
Uhm... torno sul problema della massa relativistica.
 
Sto leggendo "Dal Big Bang ai buchi neri" di Hawking e in uno dei
capitoli iniziali si dice che, siccome l'energia e' equivalente
alla massa secondo la nota equazione, man mano che un corpo
accelera la sua massa complessiva aumenta e quindi diventa sempre
piu' difficile accelerarlo, per cui la velocita' della luce non
si puo' superare ed un corpo con massa a riposo avrebbe bisogno
di energia infinita per raggiungere c.
 
E' corretta questa impostazione ?
Inoltre, se la massa aumenta effettivamente, il resto
dell'universo ne risente ? Cioe': se un corpo si allontana da me
a velocita' relativistiche, l'attrazione gravitazionale di quel
corpo verso di me AUMENTA ?

(naturalmente, tenendo conto della distanza che aumenta,
l'attrazione complessiva puo' anche ridursi, ma volevo sapere se
la massa del corpo in allontanamento bisogna scriverla

effettivamente aumentata nella formula F=k*m1*m2/d^2)

 

Vinicio Coletti - http://www.webcom.com/vcoletti

vcoletti@webcom.com


This mean that we should compute the gravitational attraction taking into account also the relative speed of the bodies, and the Newton formula should become:

F = G q2  m1  m2
-------------
d2

where each body mass is considered increased by the speed (q is the increase factor that depends on the speed).

Cosmological effects

Since our universe is expanding, the speed at which two galaxies go away each from the other usually increases with the distance.
The universe is very large, so most galaxies are very far and going away very quickly from us (and from whatever site).
This mean that at the cosmological level the effects of relativistic mass are very important because gravity is stronger at so high recession speeds.
In my opinion, this could also mean that there is not missing mass in the universe.
Perhaps, using the q factor and computing this way the gravity, we could discover that the observed expantion rate of the universe is totally coherent with the observed matter density (or at least much less incoherent than today).
Send your feedback

Addition of October 30, 2002

If you tought it was too strange to propose a modification of the Newton laws about gravity, well, I have recently discovered that I am not alone.
When I bought the October 2002 issue of the Italian magazine "Le Scienze" (which publishes many of the articles of "Scientific American") I kept staring at pages 42-50, the mouth open...
What Le Scienze publishes is an article by Mordechai Milgrom, professor of physics in a Middle East research institute.
Prof. Milgrom proposes a theory named MOND (MOdified Newton Dynamics) stating that at very low values of the acceleration constant, you need less force, compared to plain Newton laws, to induce acceleration to a certain mass. This explains fairly well how matter behaves in large galaxies, without any needs of dark matter.
Milgrom introduced this idea with the article "A Modification of the Newton Dynamics as a Possible Alternative to the Hidden Mass Hypothesis" in the Astrophysical Journal 270, pp. 365-370 of July 15, 1983.
 

There are several things to say about these two ideas:

However, I don't know (that is I have not computed) how this could actually modify the behavior of matter in galaxies, galaxy groups and so on. Ideally, one should simulate the distribution of mass in a galaxy and compute all relative speeds and gravitational forces acting on each simulated body.

If you want to know more on MOND theory and Mordechai Milgrom, here are a few links.


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