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Nature of Inertia and the Emptiness of Space

  1. Nov 30, 2012 #1
    While this may seem like a silly question, I had difficulty answering it completely.
    "If space is a vacuum, why aren't we somewhere else already?"

    If it is truly empty, devoid of any substance or mechanism whereby it might restrain or compell the action of an entity, what keeps entities apart? If "inertia" is the answer, from whence is inertia derived? What permits acceleration to accuumulate for a given object and an object's motion at one location to be passed on to that of the same object at another location--is it a property of that object, a property of space, or both?
  2. jcsd
  3. Nov 30, 2012 #2
    Space is only a vacuum when you are using the perspective that all matter consists of finite particles. From a field theory perspective, all matter is contained in fields which occupy all space. For example the 'electron' has an electrostatic field with infinite range.
    These two viewpoints are mutually incompatible.
    The mystery that whatever is 'actual reality' can be perceived/measured either way with equal facility is resolved when one mathematically generalizes the second order differential equations of physics to four-tensors. In that domain (Minkowski space) the selection of a 'viewpoint' amounts to the application of an operator to rotate the representation into a different coordinate system.
    A photon can be handled mathematically as an oscillating E-M field (a 'wave') distributed through all available space, or as a point 'particle' moving from A to B at the speed of light, all depending only on your chosen frame of reference. Thus the legendary wave-particle duality arises.
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