Newton's vector equation for gravitation states that each particle in the [[universe]] attracts another particle with a force directly [[proportion]]al to the product of their masses and inversely proportional to the [[exponentiation|square]] of the distance between them<ref>Serway and Beichner, Physics for Scientists and Engineers, Fifth Edition</ref>, or: | Newton's vector equation for gravitation states that each particle in the [[universe]] attracts another particle with a force directly [[proportion]]al to the product of their masses and inversely proportional to the [[exponentiation|square]] of the distance between them<ref>Serway and Beichner, Physics for Scientists and Engineers, Fifth Edition</ref>, or: |