https://superphysics.org/material/principles/part-2/chapter-04/section-02/ Recent content in Physical Time on Superphysics Hugo en Sat, 30 May 2026 00:00:00 +0000 https://superphysics.org/material/principles/part-2/chapter-04/section-02/unit-01/ Sat, 30 May 2026 00:00:00 +0000 https://superphysics.org/material/principles/part-2/chapter-04/section-02/unit-01/ <h2 id="why-humans-still-use-60-and-24">Why Humans Still Use 60 and 24</h2> <p>Before clocks, humans used the only two reliable cycles in nature: the <strong>day</strong> (sun) and the <strong>month</strong> (moon).</p> <ul> <li><strong>Egyptians (c. 1500 BCE):</strong> The first to break the day into smaller parts. Using star patterns (decans), they divided the night into 12 sections and, later, the day into 10 hours plus twilight hours. This gave them a <em>24-hour</em> day—though the hours varied in length with the seasons.</li> <li><strong>Chinese &amp; Indians:</strong> Used water clocks (clepsydras) and incense sticks with knots or smells to mark equal intervals. The Chinese divided the day into 12 double-hours, linked to their zodiac.</li> <li><strong>Europeans (Medieval):</strong> Inherited the systems of Rome and Greece, who used sundials and water clocks but often divided daylight into just 12 “temporary hours.”</li> </ul> <h3 id="the-babylonian-base-60">The Babylonian Base-60</h3> <p>Around 2000 BCE, in modern-day Iraq, the Sumerians and later Babylonians didn’t count on their fingers (10) but on the knuckles of their fingers (12 on one hand, multiplied by 5 fingers on the other = 60). Their entire math system was <strong>sexagesimal (base-60)</strong>.</p>