By Ira Mark Egdall <\/p>\n
My cousin sent me this quote from a religious site and asked me what I thought of it:<\/p>\n
“Gravity is a theory, not a proven fact. <\/p>\n \u201cThe effects of gravity can be explained by other theories. An example would be the acceleration theory which asserts the earth is actually moving ‘upward’ at a constant rate of 1g (9.8m\/sec^2). This produces the same effect as \u2018gravity\u2019. <\/p>\n \u201cSee there are different theories for the same phenomena – and none are facts, they are just theories.\u201d<\/em><\/p>\n Oh boy. There is such misunderstanding on what a theory is and is not. First of all, a theory in physics is a \u201cmodel\u201d using mathematics to try to describe physical behavior. And no scientific theory is \u201cproven\u201d. You would have to test it against all possible scenarios, which are infinite in number. All you can do is rate the usefulness of a theory — how well its predictions agree with measurements and observations. The theory of gravity (here I assume they are talking about general relativity) is considered superb in its usefulness. Volumes of empirical data from a number of independent sources confirm its predictions to extraordinary accuracy.<\/p>\n As someone said; to say \u201cit is just a theory\u201d is like saying it is just science.<\/p>\n Per Einstein\u2019s Equivalent Principle, acceleration produces the same physical effects as gravity. This is no doubt the source of the argument above. But the Equivalence Principle (EP) does not tell the whole story. A quick summary: the EP only takes into account the warping of time by a mass\/energy. But mass\/energy also warps space. So the effects of gravity and acceleration are not truly equivalent. Thus an accelerating Earth at 1g would not produce the exact same effects as gravity. Obviously, the writer has read some popularizations, but does not know the subtleties of the physics. (The Devil is in the details).<\/p>\n I didn\u2019t know any of this until I did the detailed research for my book on Einstein and relativity. Sorry for the rant, but the quote above got me all excited. And these days, I get my thrills wherever I can find them.<\/p>\n Note: I read about rating the usefulness of physics theories in Roger Penrose\u2019s book The Emperor’s New Mind, Concerning Computers, Minds, and the Laws of Physics<\/em>, p. 152-155.<\/p>\n","protected":false},"excerpt":{"rendered":" By Ira Mark Egdall My cousin sent me this quote from a religious site and asked me what I thought of it: “Gravity is a theory, not a proven fact. \u201cThe effects of gravity can be explained by other theories. An example would be the acceleration theory which asserts the earth is actually moving ‘upward’ … Continue reading “Just a Theory”<\/span><\/a><\/p>\n","protected":false},"author":11,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[3,4,5,8,9],"class_list":["post-55","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-einstein-albert","tag-einsteins","tag-elbert-einstein","tag-what-is-relativity","tag-who-is-einstein"],"_links":{"self":[{"href":"http:\/\/blogs.scienceforums.net\/ime\/wp-json\/wp\/v2\/posts\/55","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/blogs.scienceforums.net\/ime\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/blogs.scienceforums.net\/ime\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/blogs.scienceforums.net\/ime\/wp-json\/wp\/v2\/users\/11"}],"replies":[{"embeddable":true,"href":"http:\/\/blogs.scienceforums.net\/ime\/wp-json\/wp\/v2\/comments?post=55"}],"version-history":[{"count":0,"href":"http:\/\/blogs.scienceforums.net\/ime\/wp-json\/wp\/v2\/posts\/55\/revisions"}],"wp:attachment":[{"href":"http:\/\/blogs.scienceforums.net\/ime\/wp-json\/wp\/v2\/media?parent=55"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/blogs.scienceforums.net\/ime\/wp-json\/wp\/v2\/categories?post=55"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/blogs.scienceforums.net\/ime\/wp-json\/wp\/v2\/tags?post=55"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}