Doesn't matter. Anything would be arbitrary. Just pick one and be done with it, and we already have GMT and UTC.
In 1998, the Swiss watch company Swatch introduced the concept of a decimal Internet Time in which the day is divided into 1000 'beats' so that each beat is equal to 1 minute 26.4 seconds. The beats were denoted by the @ symbol, so that, for example, @250 denotes a time period equal to six hours.
So far this system has not caught on
http://www.abc.net.au/science/articles/2011/11/15/3364432.ht...
It's the exact same information needed both today and after doing away with timezones.
If you're in the same place as the other person, there's no confusion at all. If everybody uses GMT, you know e.g. that diner around your parts (e.g. London) is around 19:00 (7pm). If you live in California you know that diner around your parts is around 03:00 (3am).
If you're in different countries, e.g. one is in London and the other is in California, "Let's have a Skype at around 11:00" is unambiguous -- it will be 11:00 at both your clocks.
Lastly, if you're in different countries and you want to call someone in California, and wonder whether now (11:00 GMT) is a good time, you just have to know the offset number (the sun rises there 8 hours later) which is the same as knowing the timezone.
Without timezones, it's only knowing the "part of the day" (whether it's late or dusk or sunrise time etc) in another place that requires knowing an offset (similar to knowing the timezone offset today).
All other calculations and coordination is vastly simplified.
>(e.g. "Let's have dinner Wednesday night" would be very confusing in some parts of the world. "Is that the Wednesday night just after Tuesday night? Or the one just before Thursday night?")
How is that confusing? Assuming we're talking about dinner, it would have to be dinner time in the place those people live. So, e.g. a little before or after sunset time on Wednesday. Whether that corresponds to 7pm or 2am or 12pm, people will know when it's that time where they live.
You waive off my dinner example as if "dinner" is a rigid set time. It's not. I'm in New York and I eat dinner at 6pm sometimes. Other times I eat at 8pm. Under UTC, this means that I sometimes have dinner on Wednesday at 23:00 and other times I wait until Thursday at 01:00. Asking someone over for "dinner on Wednesday" would always be ambiguous.
Here are some other confusing examples, if the dinner one doesn't illustrate it:
(At work)
"What days do you have off this week?"
"I got Tuesday/Wednesday and Friday/Saturday off"
"When is the paper due?"
"Tuesday"
"The class that starts on Tuesday or the
one that ends on Tuesday?"
We could acclimate to all of this, sure. But we'd still have timezones. It wouldn't be immediately obvious to the Londoner that 11:00 is a terrible Skype time for her California colleagues (3am). So I don't see the gain here. Dealing with time differences is a fundamental aspect of living on a ball Earth.