Time, at least on the larger scale, is typically “measured” in days and years, using the rotation of the Earth and the orbit of the Earth around the Sun respectively as reference. When the Earth completes “one full rotation,” a day is said to have occurred. Similarly, when the Earth completes “one full orbit” around the Sun, a year is said to have occurred. However, on the smaller scale, a different reference is typically used.

The “most accurate measure” of time is kept by atomic clocks. An atomic clock is a device that counts very brief changes in atomic and subatomic particles. That is, in modern atomic clocks, when an electron changes energy levels it emits an electromagnetic pulse that the clock can detect; the atomic clock counts these pulses and determines that a specific amount of time has passed upon detecting the specified number of pulses. Putting this another way, through scientific inquiry it has been determined that electrons will change energy levels in certain elements (at very specific temperatures and other conditions) at certain specific intervals, thus the atomic clock, upon counting an appropriate number of these changes, can report that a specific amount of time has passed.

I admit that even this brief description of how an atomic clock works is over-simplified, but the basic structure of counting events is still present in the process of “measuring” time. If I assume that the event in question is sufficiently regular and reliable, then I can simply count the events to determine how much time has passed in a particular situation. Atomic clocks are considered to be very, very accurate—given that the conditions under which the atomic clock operates are kept as constant and unchanging as possible—when compared to other sorts of time keeping devices, such as wristwatches which often use a quartz crystal and count the oscillations of the crystal’s natural vibrations.

It is not strictly important to understand the very particular nature of physics and the universe to follow what I am suggesting here. Each situation of time measurement is essentially the same: find a naturally occurring event, one that is considered to be reliable and regular, and then count those events in order to determine an accurate accounting of time. Whether one uses the rotation of the Earth, or the vibration of atoms, in theory the end result should be the same. Variance should generally only occur if the reference I select is less reliable or less regular for some reason. It is generally considered the case that the vibration of atoms is much more reliable and regular than the rotation of the Earth, and thus those time measuring devices that use a reference of the vibration of atoms are considered more accurate and precise than those that rely upon the rotation of the Earth. And thus, if there is a difference between the time measured on different devices, the one that is considered more accurate should be used to correct the one that is less accurate. And this is where the idea of leap years and leap seconds enter into the discussion.

As I had suggested in my previous post, the rotation of the Earth about its axis, and the orbital period of the Earth about the Sun, are not consistent. How do I know this? Because when I use other methods of measuring time, I find that the time it took for the Earth to rotate, or the Earth to complete an orbit around the Sun, is different from one count to the next. If the last orbit of the Earth around the Sun occurred within 365.24221 days (according to a particular atomic clock), and the current orbit occurred within 365.24220 days (according to the same particular atomic clock), and then another measure from another previous orbit occurred within 365.24219 days, then I would suggest that either the orbital period is changing with each orbit, or the event that the atomic clock is using to measure time with is not as regular or reliable as I might think. Or it is also possible that both methods have error to them, and that neither event I am using as a reference is entirely reliable and regular. The general consensus by the international community of humans on this planet suggests I take the atomic clock as most accurate. If you want to learn more about this, I’d suggest starting here.

At this point, many of my friends and family will suggest I am being far too pedantic. That it is not so important to worry about such minor differences between everything. It doesn’t affect most people’s day-to-day lives whether one time measuring device is more or less accurate than another, so long as we can all agree to one standard. And, for the most part, they are correct. The standard that virtually all human beings agree to is that from the point in time the Sun is at its highest point in the sky, to the point in time when the Sun is again at the highest point in the sky is exactly one day. Most people are not interested in the measure provided by the atomic clock, even if science will tell us that its information is far more accurate. Furthermore, when the time comes to synchronize our clocks, it is the atomic clock that will be adjusted to conform its measure of time to the rotation of the Earth by adding or subtracting seconds to its value. These are leap seconds.

In a similar move, the orbit of the Earth around the Sun does not occur in a time frame that coincides nicely with the rotation of the Earth. That is, in the time it takes for one complete orbit of the Earth around the Sun, the Earth will rotate approximately 365 1/4 times. And again, when it is time to synchronize our devices, it is the year that is adjusted to conform with the day, hence why I get one extra day added to the year every four years, except every hundred years. These are leap days.

Thus, the agreed upon measure of time is actually the day, which in turn is measured by observing the rotation of the Earth about its axis. Furthermore, the day is not a complete rotation of the Earth about its axis, but something slightly more than a complete rotation, as the measure is made by observing when the Sun is at the highest point in the sky until it is again at the highest point in the sky. All other devices and measures are adjusted in accordance to this standard. Why this may seem unimportant to most people is that most people exist and spend the entirety of their lives on the Earth, where making such observations are so easy as to be unremarkable. However, if any humans were to leave the Earth, to perhaps colonize Mars, or to explore beyond our solar system, it becomes a great challenge to figure out what time it is.

Having now established how time is measured and maintained for humans upon the Earth, it is time now to take this discussion in another direction. I have some idea of how time is accounted for. I can say that it is Sunday, May 31, 2020 at about 2:41 pm, and I can feel quite confident that if you are a human being living upon the Earth, you will understand what I mean and when I mean. But this still doesn’t really answer any questions regarding what time might be in itself. In fact, the best I can say at this moment is that time, for humans on the Earth, is simply a count of various agreed upon reliable, regular events. So what is time in itself?

The past. The present. The future. These are all terms used to help describe time. They are relative references; relative to the now. The past occurs before the now; the present occurs simultaneously with the now; the future occurs after the now. But what is the now?

Now is a term I use to describe the temporal location when I am. It is hard to describe exactly, except to say that I am always in the now. As soon as I remember something, that something is already in the past, having occurred before the now. The future often includes those events I want to eventually occur in the now. When I consider my conscious self—what I often referred to as “I”—that conscious self always exists in the now. I cannot exist consciously in the past or in the future. Remembering the past is not existing in the past, just as expectation of the future is not existing in the future. My conscious self is always existing in the now. My conscious self is a reference point I can use; a reference to the now.

Thinking in this way, I quickly notice that time is always relative to me, specifically to my conscious self. Every event occurs either before, simultaneously with, or after the now. Can I quantify these terms any further, that is, can I suggest that there is a long before and a shortly before? Saying long before seems to suggest a quantifiably large value of time, just as shortly before seems to suggest a quantifiably small value of time. However, as I will demonstrate, really all that is occurring is a larger or smaller number of other events between the now and the event that occurred either long before or shortly before.

Consider how we determine time. While I write this post, it is Sunday, May 24, 2020 at about 10:48 am. This is a very specific reference I am making, though I could be even more specific had I chosen. But what precisely does it mean? Sunday is a description of the “day of the week,” often considered the first day of a seven day sequence of days. The selection of the “first day” of a sequence of seven days is fairly arbitrary. May is the month, made up of thirty-one days, and is also considered approximately one twelfth of a year. The 24 is a reference to the twenty-fourth day of the month being considered. The 2020 is the year, counted from an arbitrary point in the past. The two terms that need further explanation are day and year, as both seem to tell us a great deal about the particularity of the values in this description.

So what is a day? It is suggested by most that a day is one full revolution of the Earth about its axis (given that the Earth’s axis is tilted approximately 23.5 degrees, though that value changes over time). If we assume this is the case, then when the Earth rotates a full 360 degrees, a day has occurred. It is suggested that a year is one full orbit of the Earth around the Sun. If we assume this is the case, then when the Earth completes a full orbit of 360 degrees around the Sun, a year has occurred. However, in both cases, the rotation and orbit of the Earth are inconsistent. That is, the rotational speed of the Earth fluctuates as does the speed at which the Earth orbits the Sun. Furthermore, the Earth’s orbit is not entirely consistent either, straying from the path it takes slightly upon each circuit. These variances can be accounted for by the influences of other celestial bodies. The Earth is not alone in the void of the cosmos.

While those variances are generally quite small, to be imperceptible and likely negligible, if I am to determine an accurate account of time, those variances need to be considered. Furthermore, there is reason for me to believe that these values are themselves suspect. Consider the motion of the Earth around the Sun. When the Earth completes one full rotation, it is no longer in the same position it was in at the beginning of its rotation. Both rotation and orbit occur simultaneously. I will use the following diagram to emphasize my point:

When the Earth rotates about its axis, it moves along a trajectory around the Sun. If at one position (A), the direction the Earth faces relative to the Sun is with the arrow pointed at the Sun, at another position (B), the arrow will be pointed perpendicular to the Sun. That is, in each new position the Earth is in after completing a full 360 degree rotation about its axis, the Sun will appear at a different spot in the sky, if I am an observer standing on the Earth (assuming I remain stationary relative to the Earth).

This description of a day does not seem consistent with other ways of describing a day. For example, I have often heard a day described as the time it takes for the Sun to reach the highest point in the sky from when it last was at the highest point in the sky. Following from this description, if I suggest that the Earth will complete approximately 365 full rotations about its axis when it completes approximately one full orbit around the Sun, then a day is actually closer to a 361 degree rotation about its axis, or slightly more than a full rotation.

It is not important here for me to determine with perfect measured accuracy precisely how much of a rotation of the Earth constitutes a day, nor how many days there are in a year. What is important to notice is that all of these time determinations are all relative to events. In particular, not only are they concerned with what comes before, simultaneously, and after, but they are also concerned with counting relatively regular events, such as the number of times the Earth rotates on its axis, or the number of times the Earth completes an orbit around the Sun. The year 2020 is suggesting that since a particular prescribed event had occurred in the past, the Earth had completed 2020 orbits around the Sun. The date of May 24 suggests that since a particular prescribed event had occurred in the past, the Earth had completed 145 approximately full rotations about its axis. In order for me to understand what these descriptions mean, I need to know the particular prescribed events. I need to know that the reference for the year is relative to the occurrence of when Jesus had been born according to the Christians. I need to know that the reference for the day is relative to the arbitrarily decided upon event that is considered the beginning position of the orbit of the Earth around the Sun.

The description of 10:48 am can be described similarly, though instead of counting full occurrences of the Earth’s rotation about its axis, I will need to approximate the fractions of a rotation. For example, to say 10 am is to say that the Earth had completed 5/12 of a full rotation since the particular prescribed event of when the Earth was last facing away from the Sun (relative to my position on the Earth, based on time zone, etc). There are 24 hours in a day, so an hour is one 24th of a rotation. There are 60 minutes in an hour, so a minute is one 1440th of a rotation. There are 60 seconds in a minute, so a second is one 86400th of a rotation.

Therefore, when described in this way, time is simply a description of what is before, simultaneous, and after. In order to introduce some sort of quantifiable measure into the description, a count of regularly occurring events is added to the description. For example, long before will include a larger count of event occurrences than shortly before. This is one manner in which time is often described, however, it is not the only manner. As I’m sure you may already be aware, time on the smaller scale (minutes, seconds, etc) are not usually described by fractions of days, but by counting a different reference event. That will be the subject of my next post.

There are plenty of things to talk about, and I will get to many of them eventually. However, I will begin with the topic that I end up talking the most about: time. The more I read and study and discuss, the more I tend to think that it does not exist. At least, not in itself. That is, time is a concept I use to describe something, so it does exist as a way for me to describe that something. But as a thing in itself, like a book or a table, perhaps not. Or even as an intangible thing, like gravity or magnetism, again I am not convinced.

This is an incredibly controversial position to hold. But if one thinks about it, perhaps it is not as controversial as one might think. After all, no one has “seen the effects of time,” at least not directly. When one suggests they do, what they really are suggesting is that they see erosion, or they see wear-and-tear, or they see old age. They do not see time, nor do they see the “effects of time.” They see the effects of erosion or wear-and-tear or old age. Time is a literary tool used to capture the plethora of effects we want to describe, so time is a way for me to describe something. But I am still not talking about time itself.

So what is time exactly? Or, when I want to talk about time itself, what am I trying to talk about? I think when time is used, it is used in various ways, which further confuses what it might be. Sometimes, time is intended to be a position on a long thread, similar to the idea of a location in space. In this way, one might be able to “travel” from one position to another, able to affect things related to that position. Thinking about time in this way, I think, is most common, and influences many science fiction stories and discussions. However, like locations in space, to “travel” from one position to another, I first need to occupy a portion of time, like I occupy a portion of space.

In the case of locations in space, I describe my manner of occupation in terms of length, and width, and depth. I am an irregular object, about two meters in length, perhaps three quarters of a meter in width, and maybe a half a meter in depth, though I do not fully occupy all of these dimensions. In similar fashion, I occupy a portion of time. I might call this dimension duration. That is, I occupy a portion of time that is the duration of my existence. Presently, I exist, and so now is a part of my duration. Many years ago, I began to exist, and so my duration would have began at that time. When I cease to exist, that will be the end of my duration. I will occupy about 80 years of time, though until I cease to exist, I won’t know for certain. This assumes that my existence began when I was born, and ends when I die; if my existence goes beyond, like if there happens to be life after death, then perhaps I will occupy much more time than I think.

This occupation of time could make travelling to another position tricky. When one thinks about “time travel” one usually assumes that their present self is all that they are, and so travelling to other positions in time seems mostly unproblematic. However, if I occupy a significant portion of time, how then might I change positions successfully? Does my “past self” need to travel back 10 years when my “present self” travels back 10 years? If I dismiss that I occupy time, as is often the case, then it leads to various paradoxes where I exist multiple times in the same position in time. Again, many science fiction stories have fun exploring what precisely might happen given these circumstances.

It seems like I’ve created a big mess already, and I’ve barely scratched the surface. If time is like a thread, and if I occupy a portion of that thread, then it seems to bring with it a lot of complications. Is time a bit like an empty space along a path that I take? In my next post, I will put many of these crazy ideas to the side while I try to get a better handle on what time is by considering how time is used in the literary sense.