These numbers, such as the speed of light or the gravitational constant, define how everything works in our universe. But lots of physicists think the numbers m

These numbers, such as the speed of light or the gravitational constant, define how everything works in our universe. But lots of physicists think the numbers might not actually be constant. In my ignorant, non-physicist head, gravity always struck me as a force that would make sense as variable. Maybe that would explain all the missing 'dark matter', or even provide an alternate explanation as to why so many species on our planet were larger millions of years ago (assuming an explanation for these two phenomena isn't self-contradictory, which, given my lack of physics background, it might well be!)