GMT and UTC:
Greenwich Mean Time (GMT) is originally referring to mean solar time at the Royal Observatory in Greenwich, London. GMT and Coordinated Universal Time (UTC) can be seen equivalent when fractions of a second are not important.
EST time now. Current Eastern Standard Time (EST) now in USA and Canada. Time-time.net for current time information of cities around the world.
time-time.net
“Gravity slows down time … speed slows down time ...” astronomer Bob Berman
Due to aberration, the cosmos to the observer seems to concentrate, where at SOL the entire cosmos would appear to be a single bright dot in the direction of travel. paraphrase of B.B.
"...a clock that is moving [accelerating] closer & closer to the speed of light (SOL) will tick at a slower & slower rate. If that clock were moving literally at the speed of light, it would never tick at all. No time would pass for that object that moves at exactly the speed of light." physicist / historian David Kaiser MIT -PBS Nova: Particles Unknown
On this day [November 18] in 1883, railroad companies in the United States and Canada transformed time in both countries, leading to the ground-breaking concept of time zones around the world.
For millennia prior to this date, many people around the world measured time based on the placement of the Sun, with midday (or "high noon") determined by when the Sun was highest in the sky over that particular village or town. Mechanical clocks eventually started replacing sundials in the Middle Ages. Towns would set their clocks by gauging the position of the Sun, leading every city to operate on a slightly different time. This method lasted well into the 1800s, when there were at least 144 different time zones in North America.
Since many people didn't travel especially long distances from their homes throughout history (generally as far as a horse, camel or wagon could carry them on land) this rudimentary form of timekeeping didn't cause much of a problem – that is, until the advent of the railroad.
The invention of railroads ushered in a new era of land travel, and forever changed the way humans perceive time.
www.bbc.com
Who invented Daylight Savings Time?
Benjamin Franklin first introduced the idea of daylight saving time in a 1784 essay titled “An Economical Project.” But the modern concept is credited to George Hudson, an entomologist from New Zealand, who in 1895 “proposed a two-hour time shift so he’d have more after-work hours of sunshine to go bug hunting in the summer,” the National Geographic reports.
The concept resurfaced during WWI as a way to save energy. The idea was that people would spend more time outside and less time inside with the lights on at night and, therefore, conserve electricity.