<p>What happens to an hourglass in microgravity? Do the grains of sand stop falling since there’s little or no gravity?</p>
<p>Correct. However, that is not to say time itself stops or any nonsense like that. As you know, hourglass is only an earthly way of keeping record of time.</p>
<p>Thanks. I was also wondering if there was some way to figure out how fast the grains of sand will fall depending on how ‘micro’ the microgravity is… like different gravitational pulls.</p>
<p>Oh definitely. I mean you can give whatever arbitrary variable for measuring how “micro” gravity is; however, newton’s already done that. G (6.67 * 10 ^ -11) times mass of whatever’s causing the gravity divided by the distance between the center of mass and the grain of sand. This equation will give you the acceleration of the grain of sand, and from it, you can calculate how fast it will be before it hits the botton of the hourglass.</p>