I visit a remote uninhabited island and photograph the cliffs. I return a year later and notice that in one area the cliff is reduced in size. Part of the rock face has collapsed and fallen into the sea; at the base of the cliff is a pile of boulders visible at low tide.
Erosion by the sea has had its effect, the displacement of sandstone from a high position to a low position or, to put it slightly differently, some pieces of matter have moved from one place to another.
But is this significant? Does this rearrangement of matter ‘matter’? Not much, we might reply, and add, not at all, if we recall the fact that the island is uninhabited, rarely visited and that the life of no person or animal is in any way improved or diminished as a consequence.
The implication is that an event ‘matters’ only when a human person or animal is in some way affected by it. And I think that we can be more precise in what is meant by a person or animal being affected.
Suppose one hair on my hand disappears in the middle of the night while I am asleep. The next day neither I nor any other person is aware of this change. Nobody notices, nobody feels any difference. An event has happened to part of my body but it is without any consequence as far as anyone knows. Does it matter? Again, as in the case of the falling rocks, I can understand no sense in which it does ‘matter’ in the slightest.
If a parallel universe were to exist consisting entirely of inanimate objects, of lifeless planets and stars and galaxies and if it had no impact on any other universe and if this universe were to explode, splinter, to disintegrate and even cease to exist totally, would its disappearance matter in any way. Again, in my view it would not matter, not matter at all.
For an event to ‘matter’, that event has to impinge on an experiencing, conscious being. For something to matter there has to be an impact in consciousness.
Nothing matters in itself. If something causes a sentient being pain, anxiety, pleasure, delight, then it matters to that being. There is no such thing as mattering in isolation. Is there?
Consciousness and Other Matters 