@John, of course the problem lies in conflating “tomorrow” with “24 hours from now”: dates in the past but especially in the future should never be treated as intervals from the present. It’s not that there are two midnights on the day savings time goes into effect, it’s that there’s less than 24 hours between civil middays straddling such a change.

Of course, there are other time and calendar things that cross boundaries — the western school year starts in one calendar year and ends in the next, and there are people that work 11-7 graveyard shifts — but my guess is that having a calendar day match a solar day is too useful to give up.

(BTW, John Cowan’s example of Kashi has a counterpart: Japan’s northern island of Hokkaido is in the same time zone as the rest of Japan and Korea, but is far enough east so that during the summer the sun sets quite early, even though Hokkaido is pretty far north and has quite long days during the summer. Personally, I think both Japan and Korea should permanently jump ahead an hour, but like Brian, no one’s going to do that on my say-so. :)

But I should emphasize again that I haven’t really thought through the consequences of this change. It eliminates some sources of confusion but would doubtless break other things. To me the big plus is that we can think of time as a monotonically increasing sequence of moments, essentially the value of a counter. The big minus is that the entire human population has to alter habits that have become pretty deeply ingrained in the few centuries since mechanical timekeeping was introduced.

In any case, not to worry: No one is about to adopt such a plan on my say-so.

Only if you think the concept of working in the daytime and sleeping at night has lost its usefulness. Our bodily cycles are still synchronized by the Sun, despite working in windowless offices and staying up late with electric lights; even in a large city like New York, only about 6% of the population works the graveyard shift.

At present the worst case is the city of Kashi (Kashgar) in extreme western China, which is on Beijing time (UTC+8) even though its solar time is more like UTC+5; it’s at about the same longitude as New Delhi. Office workers there begin work at about sunrise and go home in mid-afternoon, solarly speaking.

The only fully general solution to the calendar problem is to allow all future dates to be specified in the local civil time (LCT) of a particular location. Financial instruments such as bonds, options, and futures, for example, are usually specified with respect to a certain date at 5 PM New York or London LCT. This cannot be directly converted to an unvarying standard such as UTC, because Congress or Parliament might alter either the DST hours or even the underlying standard time zone as a whole at that location before the event occurs.