<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Larry Burford</i>
<br />wouldn't the diameter of a gravitating mass also influence the length of its shadow? This sould be true for both "solid" objects (like planets and stars) and extended objects like galactic cores and galaxies.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">No, you are thinking of shadows cast by a unidirectional source of illumination such as a flashlight or the Sun. For material bodies, the 1-2 kpc "shadow" is cast by each individual matter ingredient (MI), and it does not matter how many MIs are in the body. If one MI casts a shadow of length L, then N matter ingredients cast N shadows of length L.
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Intuitively it seems that, for any given value of the graviton MFP, the shadow of a proton would be shorter than the shadow of a planet, which in turn would be shorter than the shadow of a star, etc.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">In principle, any two MIs at unlimited distance could shadow each other from some graviton impacts and therefore experience a net force toward one another. What actually sets the limit for the range of gravity is graviton-graviton collisions, which then back-scatter and fill any shadow. It is similar to the reason we cast no shadow from a flashlight ourdoors in bright sunlight. Scattered light from other sources fills the shadow. -|Tom|-
