# Discover article on gravity **URL:** \ **Category:** Factual Questions\ **Created:** [September 16, 2003, 10:26pm UTC](https://boards.straightdope.com/t/discover-article-on-gravity/202030 "2003-09-16T22:26:52Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![The\_Ryan](https://avatars.discourse-cdn.com/v4/letter/t/7feea3/32.png) [@The\_Ryan](https://boards.straightdope.com/u/The_Ryan)\ **Post date:** [September 16, 2003, 10:26pm UTC](https://boards.straightdope.com/t/discover-article-on-gravity/202030/1 "2003-09-16T22:26:52Z")
> [@](#): > > Below a transition acceleration equal to one 10-billionth of a meter per second every second- Milgrom calls it a0- the force of gravity might no longer be directly proportional to acceleration, as decreed by Newton. Instead, gravity might be slightly stronger, proportional to the square of acceleration Huh? Isn’t force **defined** as being proportional to acceleration? Does anyone know what he’s talking about? ---
**Author:** ![MC\_Master\_of\_Ceremonies](https://avatars.discourse-cdn.com/v4/letter/m/bb73d2/32.png) [@MC\_Master\_of\_Ceremonies](https://boards.straightdope.com/u/MC_Master_of_Ceremonies)\ **Post date:** [September 16, 2003, 10:36pm UTC](https://boards.straightdope.com/t/discover-article-on-gravity/202030/2 "2003-09-16T22:36:28Z")
I don’t know, it’s difficult to tell from just a short snippet, but (WAG) perhaps it means that the force needed to counteract gravity is proportional to the accelration due to gravity squared on this level. ---
**Author:** ![JaxBeachBoy](https://avatars.discourse-cdn.com/v4/letter/j/e19adc/32.png) [@JaxBeachBoy](https://boards.straightdope.com/u/JaxBeachBoy)\ **Post date:** [September 17, 2003, 3:30am UTC](https://boards.straightdope.com/t/discover-article-on-gravity/202030/3 "2003-09-17T03:30:14Z")
It is proportional, but not DIRECTLY proportional. Basically, at very low speeds, the force of gravity affects acceleration more strongly than at normal speeds. It has one proportion at a low speed, then a different proportion at higher. This is tremendously over simplified, but that is a great article (but I love reading articles supporting idea that challenge currently accepted notions). This scientist is basically taking other scientists to task for believing in the existence of dark matter, when no one has ever demonstrated that it actually exists. The article debunking the myth that suicide bombers are often uneducated pawns of higher powers was also a good read. ---
**Author:** ![The\_Ryan](https://avatars.discourse-cdn.com/v4/letter/t/7feea3/32.png) [@The\_Ryan](https://boards.straightdope.com/u/The_Ryan)\ **Post date:** [September 17, 2003, 5:49am UTC](https://boards.straightdope.com/t/discover-article-on-gravity/202030/4 "2003-09-17T05:49:41Z")
But you haven’t addressed the fact that force is defined in terms of acceleration. What is the proportion at low speeds, and what is it at high speeds? Challenging accepted notions is one thing, but this is gibberish, as far as I can tell. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [September 17, 2003, 6:46pm UTC](https://boards.straightdope.com/t/discover-article-on-gravity/202030/5 "2003-09-17T18:46:43Z")
It’s not complete gibberish, but MOND does have some serious problems. For one thing, it’s inherently inconsistent with General Relativity: You can’t incorporate MOND and the equivalence principle into a consistent model. For another, the effects would be too far-reaching: MOND would predict that we should orbit a quasar ten billion lightyears away with the same orbital speed as we do our own Galaxy. And there are self-consistency problems as well: A binary star system, say, should react differently to a galaxy’s gravity than a single star, according to MOND. That said: There are some patterns observed in glactic rotation curves which are predicted by MOND, and not by other current models. This is, of course, evidence in favor of MOND, but given its other shortcomings, it’s probably more reasonable to say that those patterns are a result of some as yet unmodelled patterns in the distribution of dark matter. If other scientists should be taken to task for believing in dark matter without conclusive proof (which, of course, doesn’t exist in science), then Milgrom should likewise be taken to task for believing in MOND with even less conclusive proof. ---
**Author:** ![The\_Ryan](https://avatars.discourse-cdn.com/v4/letter/t/7feea3/32.png) [@The\_Ryan](https://boards.straightdope.com/u/The_Ryan)\ **Post date:** [September 18, 2003, 6:59am UTC](https://boards.straightdope.com/t/discover-article-on-gravity/202030/6 "2003-09-18T06:59:13Z")
So how is force defined, if not in terms of acceleration? Would this mean gravity isn’t linear (doubling the amount of mass doesn’t double the amount of gravity)? And for small accelerations, wouldn’t squaring the acceleration result in a smaller amount, not larger?