Is there a machine that can manipulate gravity? For example, is there a machine that can triple gravity?
Glenn’s right, you can’t actually manipulate gravity. However, one interesting way to simulate zero gravity is to ride in the “vomit Comet” — there’s a company that will take you up in an airplane (for a fee) and let you experience weightlessness. The plane climbs steeply and then suddenly dips over forward, allowing a limited time “free fall” in which passengers float around the interior of the aircraft just as if they were in space.