TIL most audio recordings contain a background "mains hum" from electric power grid oscillations that can be matched with grid readings to date the clip to the second it was recorded. robertheaton.com Submitted by tildenpark t3_11bqxlz on February 25, 2023 at 5:47 PM in todayilearned No comments 3
[OC] License to work? States ranked by number of low-income jobs requiring licenses Submitted by tildenpark t3_11cwaph on February 26, 2023 at 11:28 PM in dataisbeautiful 45 comments 225
[OC] License to work? States ranked by number of low-income jobs requiring licenses