We humans claim to have five senses only, but a little introspection suggests there may be others. Most of us possess a rudimentary sense of gravity. Our bodies seem to grasp both Up and Down—although we are apparently insensitive to the weaker gravitational fields associated with small or faraway objects.
What other senses might exist? There are so many varieties of energy, each of which might be measurable by suitably-attuned senses: Gamma rays, background Big Bang energy, dark energy and so forth.
Whales and certain birds navigate by a sense of magnetism, which we claim not to detect. Of course the sense of smell is so highly developed in dogs that their world must be painted in olfactory hues and shapes we cannot imagine. Among humans, the blind often develop astute hearing and touch. Bats, of course, experience their world through a kind of sonar, a delicate sensitivity vastly exceeding simple hearing.
(From Dr. Rodger Swift’s Abandoned Lab Journal.)