Particles and anti particles are created and destroyed at the quantum foam level (as virtual) and also created as Hawking radiation, these become 'permanently' real as the associated anti particle of the pair (on average) does not escape the black hole's event horizon.
''Virtual particles exhibit some of the phenomena that real
particles do, such as obedience to the
conservation laws. If a single particle is detected, then the consequences of its existence are prolonged to such a degree that it cannot be virtual. Virtual particles are viewed as the
quanta that describe fields of the basic force interactions, which cannot be described in terms of real particles. Examples of these are
static force fields, such as a simple
electric or
magnetic field, or any field that exists without excitations that result in its carrying information from place to place. Virtual photons are also a major component of antenna
near field phenomena and induction fields, which have only very short-range effects, that do not radiate through space with the same range-properties as do electromagnetic wave
photons. For example, the energy carried from one winding of a transformer to another, in quantum terms, is carried by virtual photons, not real photons[
citation needed].
The virtual particle forms of massless particles, such as photons, do have mass (which may be either positive or negative) and are said to be off
mass shell. They are allowed to have mass (which consists of "borrowed energy") because they exist for only a temporary time, which in turn gives them a limited "range". This is in accordance with the
uncertainty principle which allows existence of such particles of borrowed energy, so long as their energy, multiplied by the time they exist, is a fraction of
Planck's constant.
The concept of virtual particles is closely related to the idea of
quantum fluctuations. Virtual particles can be thought of as coming into existence as quantities, such as the electric field, fluctuate around their expectation values as required by quantum mechanics''
wiki-Virtual particles
