Just an astrophysicist

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Original research and reliable sources

Welcome to Wikipedia. Everyone is welcome to contribute to the encyclopedia, but when you add or change content, as you did to the article Tidal force, please cite a reliable source for the content of your edit. This is particularly important when adding or changing any facts or figures and helps maintain our policy of verifiability. Take a look at Wikipedia:Citing sources for information about how to cite sources and the welcome page to learn more about contributing to this encyclopedia. Thank you. - DVdm (talk) 16:51, 31 March 2010 (UTC)

Note: for the same reason I have reverted your edits to the Tide article. Cheers, DVdm (talk) 16:57, 31 March 2010 (UTC)

Please do not add or change content without citing verifiable and reliable sources, as you did to Tidal force. Before making any potentially controversial edits, it is recommended that you discuss them first on the article's talk page. Please review the guidelines at Wikipedia:Citing sources and take this opportunity to add references to the article. Thank you. - DVdm (talk) 17:14, 31 March 2010 (UTC)

causes of earth tides

Dear Just_an_astrophysicist, DVdm was right when he advised you to cite reliable sources when you want to edit the article on Tides. I took a look at the edits you made and I very much regret that I have to say they were just part of a very common misconception. Tides are fully caused by the gravitational pull of the moon and the sun. Centrifugal movements (or forces) have no effect at all! Before you want to make another edit and add your "second cause" to the explanation of tides, just have a look at this website. My advise is to read this very thoroughly. The reason I advise Simanek's site and not a textbook is that the site is dedicated to just this one subject and it is very easily accessible (in terms of getting access (much more easy then lay your hand upon a particular book), but also because the wording makes it quite easy to understand). I very much hope this will deepen your insight in the tidal phenomenon and that it will prevent you from making the same mistake a second time. Cheers! - Wikiklaas (talk) 20:49, 1 April 2010 (UTC)

Well, I wrote "in the rotating frame of reference"... centrifugal forces are just inertial forces as seen in the non-inertial (rotating) frame of reference. When we are on earth, we are in a rotating frame of reference, so I don't see why the fuss about that. As to look at the tide as the difference between the force exerted on the center of the earth by the moon and the force the moon exerts locally, then in that case you should still have tides even if the Earth and Moon were fixed on giant sticks... which is not the case. Think about it. If you impaled the Earth and Moon on giant rigid sticks, and the earth and moon dont move, then you will have no symmetric tides, but only a buldge... Only if the earth and moon fall towards each other will you have the same symmetric tides, and again that's because of the inertial forces that the tides are symmetric. That's why YOU look at the force the moon exerts on the center of mass of the Earth, because that's the one that gives you the acceleration towards the moon, the inertia of the body of water makes it buldge backward as the earth accelerate towards the moon. That same inertia is at work when considering the binary system (revolving earth + moon) and it is ADDED IN THE ROTATING FRAME OF REFERENCE of the centrifugal acceleration. We are all talking about the same thing, whether you want to call it this or that does not make any difference. Just an astrophysicist (talk)