You can use epistemology to reduce any physical concept of the universe to "a concept of the mind, like numbers" by simply stating that we are all humans with m

You can use epistemology to reduce any physical concept of the universe to "a concept of the mind, like numbers" by simply stating that we are all humans with minds, therefore anything we conceive or think of is simply a concept in the mind. Outside of our minds, however, change does occur. Stars spend their fuel, galaxies spawn and migrate, rocks orbit stars in a periodic nature. The English word "time" is obviously a concept, and no matter which human word we use for "time", it's simply one way of measuring these changes we see around us. How can we measure the elapsing period over which we observe all natural phenomenon? That is the second, that is the unit of time. There's also physics here: space-time. If we think of time as a concept of the mind purely, as you propose, then we also must consider space purely a concept as well, since Einstein proved space-time is a correct notion.