Most of these introductory articles are exracted from Volume I of the Single Monad Model of the Cosmos: Ibn al-Arabi's View of Time and Creation... more on this can be found here.
Hours, Minutes and Seconds
According to what we have now discussed in this and preceding Chapters, the day as we normally experience or observe is the minimum period of time defined by the apparent full revolution of the Heavens around the earth (see sections II.12 and III.2). The original divine creative Days are single indivisible divine 'Acts', but in the observed time that we experience, we live only one moment out of each original Day (see section II.15). Therefore, the normal day as we know it is a collection of the moments from the different divine Days of the creative Week, after the processes of 'intertwining' and 'taking-out' detailed above. For this reason, the normal day can be conventionally sub-divided apparently infinitely, and smaller units of time can be conceived and measured.
Thus, the day is conventionally divided into 24 hours, and the hour is conventionally divided into 60 minutes, which are also conventionally divided into 60 seconds each. This conventional hexadecimal system can be traced back to the time of the Babylonians; it was used by many ancient civilizations and then transferred by the Arabs to the West. In recent centuries, some more scientifically measurable definitions of these conventional units of time were introduced, specifically for the second. So this hexadecimal system is now internationally used, but after the second, smaller units of time are decimally sub-divided into 0.1, 0.01 etc., or 10-x seconds, where x could be in principle any number no matter how large (for infinitely shorter times).
Ibn al-Arabi referred to these further conventional subdivisions of observed time in Chapter 59 of the Futuhat, which is entitled 'On the Inner Knowing of the (actually) Existent and Conventional Time'. Here the original divine cosmic 'Days of event' are the actually Existent Time (al-zaman al-mawjud) while the other time-distinctions days, years, months, hours, minutes and seconds are only conventional or 'estimated' (muqaddar). There he explains:
The (observable) 'days' are many: some are long, and some are short. The shortest day is the 'monad of time' (al-zaman al-fard) in which He is in a task (55:29), so that (indivisible shortest) monad of time is called a 'day' because the (divine) 'task' happens in it: it is the shortest and tiniest time, and there is no maximum term to the longest. Between them there are intermediate 'days', the first of which is the conventional 'day' familiar in customary usage, which is divided into hours, the hours into degrees, the degrees into minutes, and so on. That goes on indefinitely, for those people who also divide the minutes into seconds. Since it is ruled by (the principle of) countability, (for them time) is like numbers; and numbers are infinite, so this division is also infinite.
But some people say that (time) is finite, and they take this matter from the perspective of what can (actually) be counted or 'numbered': those are (the people) who advocate that time is an existing essence (because it is countable), and all that exists must undoubtedly be finite. But the opposing (group) say that the countable, simply by the fact that it can be counted, does not (therefore necessarily) enter into existence, so it is not described as finite, because number is not describable as being finite. This is how those who argue against the 'single monad' (or 'indivisible atom': al-jawhar al-fard proposed by the kalam theologians) contend, (maintaining instead) that according to the intellect body is divisible indefinitely. This topic of controversy among the people of intellectual inquiry (i.e., kalam theologians and the philosophers) happened as a result of their lack of good judgment and their (only) inquiring about the meanings of words (instead of what is actually real).
However, for Ibn al-Arabi this conventional division of time also has its divine origin. He first affirms that the celestial orbs were divided into 360 degrees due to the fact that the Universal Intellect (or the 'Higher Pen') was taught by the 'Greatest Element' (see sections VI.2 and VI.5) exactly 360 kinds of comprehensive divisions of knowledge ('ulum al-ijmal), under each of which there are 360 further divisions of detailed knowledge ('ulum al-tafsil), that is 360 times 360:
So each degree (of the 360 total degrees of the outermost, all-encompassing celestial sphere) includes all that it comprizes of the details of minutes, seconds, tertiary divisions, and so on, as Allah - the Exalted - wills to make manifest (of that detailed Knowledge) in His Creation till the day of the Rising.
After that, in the same passage, Ibn al-Arabi shows that Allah appointed twelve 'rulers' (wulat, s. wali), one in each of the twelve zodiac signs, which correspond to the twelve months in the conventional year. Also there are twenty-eight 'chamberlains' (hujjab, s. hajib) in the orb of the constellations (i.e., the twenty-eight houses of the moon) which correspond to the twenty-eight days in the (divine) month (see section III.2). Finally, in the same passage he also says that Allah ordered those rulers to appoint seven 'chiefs' (nuqaba’, s. naqib) in the seven Heavens, one 'chief' in each celestial sphere - i.e., the seven orbs which correspond to the seven Days of the cosmic Week. Ibn al-Arabi then adds that each one of those groups of spirits that are associated with the celestial spheres has a living human 'deputy' or 'agent' among us on earth [I.296.27].
Ibn al-Arabi even suggests a certain divine importance for the conventional division of the day into 24 hours, in the following passage discussing the different groups of the spiritual hierarchy of the 'Friends of God' (awliya’) in chapter 73 of the Futuhat [II.2.39]:
And among them (the awliya’), may Allah be pleased with them, (are a group of) twenty-four souls at any time, no more and no less. They are called the 'Men of (Spiritual) Opening' (rijal al-fateh): through them Allah opens for the people of Allah whatever He opens of (divine) knowledge and secrets. And Allah made them according to the number of hours, one of them for each hour.
Regarding the hours of the day and the two parts of it (the daytime and the night), and their observable variations across the year and from one place to another, Ibn al-Arabi says:
Then Allah caused the (observable, earthly) daytime (nahar) and the night-time by the existence of the sun - not the (true divine) Days (ayyam). And as for what happens of (the observable) increase and decrease in the (length of the) daytime and night - not in the hours, for they are (always) 24 hours - that is because of the motion of the sun in the zodiac region which is tilted with regard to us, so the day becomes longer where it is in the high houses, and when it comes to the low houses the day becomes shorter where it (i.e. the sun) is. We said 'where it is', because when the night becomes longer for us the day becomes longer for others, so the sun is in the high houses for them and in the low houses for us. So when the day becomes shorter for us, the night becomes longer for them as we said. But the day (al-yawm) itself is 24 hours: it does not increase nor decrease, nor does it become longer nor shorter in the equinox place.
 As of 1956, the length of a second has been freed from the vagaries of the earth's motion, and is now defined by the Systemé International d'Unités as equal to 'the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium-133 atom in zero magnetic field.' This means that the values for these conventional units of time are no longer tied to the motion of the earth, and instead are tied to innate measurable properties of matter. Thus the minute, hour, day, and even the average 'tropical' year are defined as exactly 60; 3600; 86,400; and 31,556,925.9747 seconds respectively.
 In mathematics: 10-x denotes 1/10x. For example10-3 is 1/103 or 1/1000, or one thousandth. As we have seen in section I.9, there are some speculations that the shortest possible time is in fact 10-43 seconds, which is called the Planck's time. The quarrel is still going on, and the issue of the quantisation of time is not yet finally settled.