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Underground > Laboratory >

A clock in the head

14:25 / 22.09.03

Hoping this question isn't quite stupid enough for MC's Stupid Science Questions thread. But Lab mods should feel free to move it there if I'm being optimistic.
I'm not sure if I even have the right words to ask this question but I'll have a stab. As I understand it, all clocks need some kind of period that can be counted - swinging pendulums, vibrating crystals, decaying atoms etc. The brain seems to be able to measure time to some extent - at least it sends a periodic signal to the heart to make it beat, I can mentally gauge the passing of, say, a minute, and so on. I would have thought it would need some sort of 'pendulum'. Is there one?

15:36 / 22.09.03

Let me know if this doesn't help:
Circadian Rhythms info sheet.

Apparently the deal is a series of chemical events, triggered by light and modulated by "clock genes."

There's a good tutorial linked to from there.

14:46 / 23.09.03

I don't know how it works, but I've got an internal clock that seems to impress the hell out of the folks who notice...

I'm pretty good (usually well within 10%) at judging the passing of time/duration of events (even if I'm not paying attention to it) as well as knowing what time it is (generally to within 10 minutes or so).

Now, I know that experiential time is very flexible - the hours that speed by unnoticed and the minutes that take eternities to pass, the fractional seconds where things almost stand still - and that experience of time is probably regulated by attention or focus.

The question seems to be how we make correlations between this flexible experience and the Western conceit of time as something made of consistent and linear units. Psychology and metaphysics seem to be better places to look than plain old biology.....

And, yes, I know I haven't helped at all.

16:51 / 23.09.03

Check that link, iszabelle. There are links from there to the Journal of Biochronology (or is it Chronobiology?) that'll explain a few of the mechanisms.

Also, I'm not sure the idea of time as something made of consistent and linear units is a Western conceit -- some of the earliest clockwork timepieces came from China, including the Song Dynasty clock tower. That was built (and then dismantled) at about the time William the Conqueror was bonking Anglo-Saxons on the head.

The word "clock" didn't enter the English language for another 400 years.

Further back, the Chinese and the Romans used clepsydras (water clocks) at about the same time, although Egyptian sundials go further back.

Interestingly (and more to the point of this topic), the word "watch" as a timepiece comes from the idea of keeping watch... the day and night of ancient cities was divided into "watches," depending on which set of guards was stationed when.

There's a good chance there's something biological at the root of the "watch," as the period of time an average guard would be able to keep alert without nodding off or falling over. Time on a naval vessel is still measured in four-hour "watches" -- ideally, a shift consists of four hours on watch and eight hours off.

22:13 / 23.09.03

So if it's to do with light, if women we kept in light 24/7, would we not have periods? Cause im considering keeping that light on at night... Or are there "mind-clocks" and "body-clocks"?

15:35 / 24.09.03

Well, there are cycles and there are cycles. The circadian clock seems to be involved with the hormone melatonin and responds to exposure to bright light.
Menstrual stuff runs off reproductive hormone cycles (estrogen, progesterone, lutenin/lutenizing hormone, and all that stuff). The two are possibly related, but not terribly closely, I'd guess.

20:55 / 24.09.03

*damn* -Was just about to spend my life split between north and south poles to sort this problem. Hmph.