Like we saw before there are different laws of conservation .
To make things interesting, particles sometimes don't obey the law of energy
conservation. We call these particles, that exist even though they don't have
the energy to do so, virtual particles.
Virtual particles can borrow their energy from seemingly nowhere. However,
they can't borrow as much energy as they want to. There is a specific amount
of energy they are allowed to borrow and once they have used it, they have
to disappear. So virtual particles have extremly short life times.
Virtual particles are everywhere. Even places with absolutly no particles in them
(called vacuum) are bubbling with virtual particles being created and annihilated
all the time. When they are created and destroyed as virtual particle antiparticle
pair, they do have to worry about the other laws of conservation. Even virtual
particles obey some laws.
You can see such a virtual particle antiparticle pair being created and destroyed
in the animation on the right.
Even though they are "naughty" particles, virtual particles play a very important
part in our world. For example, the virtual photon is the carrier particle for the
electric force. You can imagine their function to be the same as a mailman's: they carry letters
from one electrically charged object to the other. Through these letters, the
electrically charged particles will know what charge the other one has and they will know
whether they are attracted or repelled by each other. Without virtual photons there wouldn't be an
electric force and our world would look very different indeed.