The Philosophy of Vacuum Part 24. Physicists will find it extremely interesting, covering, as it does, technical subjects in an accessible way. For those with the necessary expertise, this book will provide an illuminating and authoritative exposition of a many-sided subject." -John D. Barrow, Times Literary Supplement. | Vacuum or Holomovement 223 context a new notion of a vacuum is introduced which is not directly related to the space-time structure. Formally one introduces a vacuum state 0 through the equation uk 0 0 2 where ak is an annihilation operator of the field. There are several features of these vacuum states that make it hard to conceive of them as empty . A quantum field always has a residual zero-point energy which appears as a consequence of the nonvanishing of the mean square average of the field in its ground state. Thus although there are no field excitations present in the form of quanta there is nevertheless a residue activity which actually has experimental consequences. If we consider the electromagnetic field for example then fluctuations in this activity can be interpreted as spontaneous creation and annihilation of virtual photons or virtual particle-antiparticle pairs . vacuum polarization . When the electromagnetic field is in interaction with say the electron whether treated as a particle or a field this vacuum polarization can produce observable changes as is seen in the hyperfine structure of hydrogen . the Lamb-Retherford shift . In particle physics the notion of the vacuum state has increasingly played an important role. There are many different vacuum states with notions such as false vacuums tunnelling from one vacuum state to another Coleman 1977 unitary inequivalent vacuum states that arise in interacting quantum field theories Emch 1972 and so on. In present theories these vacuum states are treated as entities in their own right but no attempt is made to account for their variety in terms of any deeper structure. However it seems clear that the vacuum states are being treated as if they are ground states of some deeper physical process. Indeed I would like to suggst that these ground states are actually quantum states of some underlying structure which as has been indicated is limited by the special role of the inertial frame and the .
