Expert: Philip Stahl - 1/10/2009

Question
Hello. Some time ago there was a ridiculous question about losing daylight you answered. What I want to ask about is a kind of genuine lost daylight, but not through any alignments but rather the continual need to add 'leap seconds' to compensate for the slowing of Earth's rotation (as was done Jan. 1 this year). I understand if this was not done there'd be a kind of de facto loss of daylight, for example the British who normally have tea at 4 p.m. would be having it at 3 a.m. in the morning! Can you elaborate on this?  Also, as a side question, did you notice the snarky followups to those 'lost daylight' questions? What is your opinion of allowing any Joe or Jane Public to post at will like on a blog? Shouldn't the followups be reserved for experts or specialists? Just asking!

Answer
Hello,

Yes, unfortunately I remember that question. It has me now much more on the alert for nonsense (not all questions are created equally, or have a modicum of sense inherent in them!)

Re: your main question, a manner of speaking you are correct. (Though in absolute terms this isn’t true since the slowing of Earth’s rotation  would actually mean  *longer* rotation periods-  hence effectively longer days.) What is happening is humans are trying – via the artifice of adding leap seconds- to maintain their clock time in synch with Solar time.

More specifically, IF no leap second adjustments were made, then within a millennium, local noon (the local time associated with the Sun’s zenith position) would occur at 1 o’clock not 12 p.m.. Another millennium it would be around 2 o’clock so to humans who register their noon by the highest altitude of the Sun it would appear the decreasing hour angle of the Sun for the same time appears to mean “lost daylight”.

How to fix this? Many astronomers and physicists prefer that the Sun (or GMT) standard of mean solar time go the way of the dinosaurs and be replaced by International Atomic Time, since modern technology would easily permit this. Solar time purists object, however, and assert that the very precision of atomic time would significantly alter humanity’s view of time, and consciousness of it.

Consider the example you gave, which appears laughable on its face but really isn’t. If we were to transfer to rigorous atomic time and ditch solar that implies that all tangible ties to registering time by solar position are finito. Rather than endless corrections, we simply let the divergence in time (the difference between atomic registered clock time and the Sun’s position) continue, however it manifests. The payoff being we no longer have to keep adding leap seconds.

In a millennium or so we therefore get used to having the Sun slightly askew from its normal zenith position. And yes, in tens of thousands of years 4 p.m. will occur at what is NOW 3 in the morning. Brits who like their tea at exactly 4 p.m. will then be waking up to take tea in the early morning.

Can humans adjust their time perceptions to get used to this? Probably, given they certainly have ample time to do so. Of course, all the existing sundials would have to be redesigned so the biggest loss, true, would be the unconscious connection of humans to the flow of time by reference to the Sun’s position. In tens of thousands of years one wouldn’t be able to spot the Sun at the zenith, and say: “Oh, it’s noon!”  Nope it would actually be 11:00 p.m. by reference to atomic clock time.

Which is better, International atomic time or solar-GMT? Depends on what the priorities in function are! For the time being, I think people are comfortable with being able to link solar positions to time estimates. This may change with some future generation that prefers technology to less precise timekeeping.

As to your side question, I have always been of the opinion that follow-ups were intended exclusively for *experts* to add to their original answers later, or to correct small errors, typos, or to expatiate on some point after further consideration. Also, other experts might contribute their own inputs – using their names, not pseudonyms – and possibly even show where corrections or further explanations are needed in the original.

Other specialists in the field may also weigh in, as one plasma physicist did (to reference the current version of his book, 'The Fourth State of Matter',  I had alluded to in one answer) on the astrophysics forum.

As you point out, it now seems they have been opened to anyone who has 2 cents to offer, never mind the factual content or limited helpfulness.  Especially egregious were all those “follow-ups” that dismissed global warming as if it is a “pseudo-religion” as one illustrious anonymous person put it. In truth, such comments are NOT helpful at all and continue to mislead many who want to nail the facts down. Instead they regrettably prolong doubt which is really based on trying to preserve a particular form of economics, rather than science.

Other follow-ups engage in outright misrepresentation, and also misstatement of the facts or the answers. Again, these sort of things *don’t help* – they hurt the site – since they sow confusion. What is happening is portions of the Answer system are being reduced to the equivalent of random blog comments from the "peanut gallery" (never mind REx is supposed to impose standards according to the follow-up FAQ)

So yes, my take is the follow-up option ought to be reserved for the experts *or other specialists*, not the general public.

The Limbaugh -losing daylight question itself also disposes of the canard that all questions contain some innate kernel of wisdom or insight- and hence perpetuate the meme that “no question can be insipid”. Not so, because sometimes the questioner doesn’t practice due diligence and get all his “ducks in a row” (including language) before asking the expert.

Because of that, I am now less averse to applying rejections to questions I deem frivolous or fringe. They save me having to parse irredeemable nonsense, and save a bit of bandwidth.

Hope this satisfies!