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WHY do objects interact?

  1. Oct 17, 2009 #1

    This has been bugging me for a while now.

    WHY do objects interact? Suppose I kick a football with my foot. Obviously physics can explain how the ball interacts with the foot and then flies off through the air, but something appears to be missing.

    Do we take it for granted that one object can 'experience' another? It seems to me as though there is some kind of 'awareness' there for want of a better term.

    An interaction can only occur between two or more separate things right? This separation surely requires one object to be somehow 'aware' of another object for an interaction to take place.

    Can someone please offer some thoughts? Thanks :-)
  2. jcsd
  3. Oct 17, 2009 #2
    We take it for granted or as an experimental fact. You cannot do without experimental facts. There are theoretical treatments that carry out "bookkeeping" in interactions but any good theory is phenomenological: it is based on experimental facts. In particular, theories use measurable quantities in their bookkeeping.
  4. Oct 17, 2009 #3
    Thanks. So would it be fair to suggest that all energy/matter – indeed every quanta of energy – possesses some kind of 'ability to interact' that is taken as fact in physics, albeit for unexplained reasons - in much the same way as we take gravity as fact, but don't really know why it exists?
  5. Oct 17, 2009 #4
    Yes, that's right. Some "why" question can be answered, but not all.
  6. Oct 17, 2009 #5
    Thanks. Now I understand! :-)
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