This is a really excellent essay on our fluid grasp on time:

Once, when there were no time zones, our time was told by the basic movements of the sun — daybreak, daylight, peak sun, nightfall, darkness. If you were living in Samoa, people in the United States didn’t exist in the future; regardless of what time it was, everyone was still living now. Even when we decided to split our days into 24 hours, to facilitate a common understanding of time, noon in Denver still felt a little different than noon in Los Angeles. Before the 1880s, British clocks had two minute hands, one for Greenwich Mean Time and one for local. It’s likely only businessmen and sailors were interested in the former. As the world has become more regulated, time zones represent a tension between how time is thought about and planned for, and how time is actually experienced.