Various proposals have been made to replace the system of time zones with Coordinated Universal Time (UTC) as a local time.

For most of history, the position of the sun was used for timekeeping. During the 19th century, most towns kept their own local time. The standardization of time zones started in 1884 in the US.^[1]

Arthur C. Clarke proposed the use of a single time zone in 1976.^[2] Attempts to abolish time zones date back half a century^[1] and include the Swatch Internet Time. Economics professor Steve Hanke and astrophysics professor Dick Henry at Johns Hopkins University have been proponents of the concept and have integrated it in their Hanke–Henry Permanent Calendar.^[3][4][5][6]

UTC as a universal time zone is already used by airline operators around the world^[7] and other international settings where time coordination is especially critical. This includes military operations, the US National Oceanic and Atmospheric Administration and the International Space Station.^[8] Within the United States, some have cited effective international use of UTC in certain industries as evidence that a permanent national time zone would work within the United States, a change the Secretary of Transportation would have the authority to make.^[8]

• The same time is used globally, which removes the requirement of calculations between different zones.
• Possible health benefits as people who live on the eastern side of a time zone are out of sync with the circadian rhythms.^[1][9]

• The date will change during daylight hours in parts of the Americas and Asia-Pacific.
• Requires changes in linguistic terminology related to time.
• Conceptually, time zones would still be in effect as different regions would still carry out activities such as business hours, lunch, school, etc. at different UTC times, essentially trading one system for a tantamount one.
• The change would likely require a high level of effort from software developers and IT admins around the world, as nearly every modern software system needs to use time information in some fashion.^[10]

For example, at 08:00 (8 AM), with UTC-0 as a worldwide standard, the sky in the Eastern United States would look how it normally does at 03:00 (3 AM), and in China would look how it does at 16:00 (4 PM). However, in the United Kingdom, the sky would look the exact same as it normally does at 08:00 (8 AM).

• Eastern Standard Tribe
• Calendar reform
• Time in China
• Swatch Internet Time

v t e Time measurement and standards
Chronometry Orders of magnitude Metrology
International standards	Coordinated Universal Time offset UT ΔT DUT1 International Earth Rotation and Reference Systems Service ISO 31-1 ISO 8601 International Atomic Time 12-hour clock 24-hour clock Barycentric Coordinate Time Barycentric Dynamical Time Civil time Daylight saving time Geocentric Coordinate Time International Date Line IERS Reference Meridian Leap second Solar time Terrestrial Time Time zone 180th meridian
Obsolete standards	Ephemeris time Greenwich Mean Time Prime meridian
Time in physics	Absolute space and time Spacetime Chronon Continuous signal Coordinate time Cosmological decade Discrete time and continuous time Proper time Theory of relativity Time dilation Gravitational time dilation Time domain Time-translation symmetry T-symmetry
Horology	Clock Astrarium Atomic clock Complication History of timekeeping devices Hourglass Marine chronometer Marine sandglass Radio clock Watch stopwatch Water clock Sundial Dialing scales Equation of time History of sundials Sundial markup schema
Calendar	Gregorian Hebrew Hindu Holocene Islamic (lunar Hijri) Julian Solar Hijri Astronomical Dominical letter Epact Equinox Intercalation Julian day Leap year Lunar Lunisolar Solar Solstice Tropical year Weekday determination Weekday names
Archaeology and geology	Chronological dating Geologic time scale International Commission on Stratigraphy
Astronomical chronology	Galactic year Nuclear timescale Precession Sidereal time
Other units of time	Instant Flick Shake Jiffy Second Minute Moment Hour Day Week Fortnight Month Year Olympiad Lustrum Decade Century Saeculum Millennium
Related topics	Chronology Duration music Mental chronometry Decimal time Metric time System time Time metrology Time value of money Timekeeper