Those of you who have read this blog from the beginning know that I’m not a big fan of light-years. They are a “unit” so small, it takes 4.25 of them to describe the distance to our nearest star. As Douglas Adams said:
Space is big. You just won’t believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it’s a long way down the road to the chemist’s, but that’s just peanuts to space.
Light years don’t cut it. Light years want to be both a dessert topping, and a floor wax. One could make the argument that light years are useful because we can get an idea how long ago we are looking at the light of given galaxy, or star is. From every star we see light from a different time period. Well, why not just put the time in seconds? The time delay unit could be seconds. Why not designate a star with a distance in the metric system, and a time delay
in seconds with a metric prefix? I’ve used prefixes in the past to define the distance boundaries to celestial objects:
| Category | Distance | Time Delay |
|---|---|---|
| Nearby Stars | 1 Petameter | 3.33 Megaseconds |
| Far Away Stars | 1 Exameter | 3.33 Gigaseconds |
| Size of Galaxies | 1 Zettameter | 3.33 Teraseconds |
| Farthest Galaxies | 1 Yottameter | 3.33 Petaseconds |
The farthest back in time we can see when we look at stars within our galaxy are 3333 Petaseconds or 105 626 960 years. Using a Ye Olde English non-prefix we have about 106 million years as the limit of time delay. Let’s take a couple of examples:
| Star | Distance | Time Delay |
|---|---|---|
| Alpha Centari | 41 Pm | 0.136 Gs |
| Algol | 880 Pm | 2.933 Gs |
| North Star | 2.4 Em | 8.000 Gs |
| Pistol Star | 245 Em | 861.666 Gs |
I used this as an example, but it’s not a great use of Naughtin’s Laws. We might want to construct the table this way:
| Star | Distance | Time Delay |
|---|---|---|
| Alpha Centauri | 41 Pm | 136 Ms |
| Algol | 880 Pm | 2933 Ms |
| North Star | 2400 Pm | 8000 Ms |
| Pistol Star | 245 000 Pm | 816 666 Ms |
It seems we can use all Petameters and Megaseconds for stars inside of our galaxy without much heartburn. There is the distance and amount of time delay in Petameters and Megaseconds.
I was recently reading the book A Brief History of Time Keeping by Chad Orzel. The book has some interesting information, but clearly he had thought about time more than distance. It looks like he has some affinity for using metric when he states on Page 208:
Of course the speed of light is enormous—186,000 miles per second in American units, 300,000 km/s in the rest of the world.
All through the book he could not help but almost exclusively and constantly use English “metric inches” (aka centimeters). Then he offers this observation:
Given the high speed of light (very nearly one American foot per nanosecond, about the only place that measurement system is superior),…..
So the author is celebrating a pigfish description?—Feet per nanosecond, as superior? Apparently the author finds this superiority so obvious, he does not have to clarify what he means. The simple argument seems to be that a foot is a better unit than 300 mm. Is he arguing that he has a better “feeling” for the distance of a foot than for 300 mm? This “feeling” he experiences makes it superior? If the author had only learned the metric system, would a foot be anything other than meaningless? I can’t see a technical reason for the fact that light travels in a nanosecond about a foot is of any advantage in any computation. This is also about three hand widths for an adult male human. A US foot is 304.8 mm, and is only 4.8 mm from the magical length that light travels in a nanosecond. Of course the US unit is superior as it is very close to this arbitrary value of a light-nanosecond. Look how close it is to an abstract value of a male human adult foot—amazing!
Let’s suppose for a moment that one wanted to measure the distance over a long interval using one’s body. Well, putting one foot in front the other would be tedious. Apparently the US Military realized this, and does not address using feet. Instead, they use pace count. It is stated online that “A pace is equal to one natural step, about 30 inches long.” Why not 36 inches? I guess feet and yards are not as perfectly attuned to the body that one might expect this “natural system.” I expect an Asian pace might on average be shorter than those of the Nordic countries. I can tell you Sven’s is much longer than mine. What to do?
Well here is the suggestion—calibration:
One way to measure ground distance is the pace count. A pace is equal to one natural step, about 30 inches long. To accurately use the pace count method, you must know how many paces it takes you to walk 100 meters. To determine this, you must walk an accurately measured course and count the number of paces you take. A pace course can be as short as 100 meters or as long as 600 meters. The pace course, regardless of length, must be on similar terrain to that you will be walking over. It does no good to walk a course on flat terrain and then try to use that pace count on hilly terrain. To determine your pace count on a 600-meter course, count the paces it takes you to walk the 600 meters, then divide the total paces by 6. The answer will give you the average paces it takes you to walk 100 meters. It is important that each person who navigates while dismounted knows his pace count.
Every person is metrologically different? Say it’s not so John Quincy Adams! There are further complications:
(1) There are many methods to keep track of the distance traveled when using the pace count. Some of these methods are: put a pebble in your pocket every time you have walked 100 meters according to your pace count; tie knots in a string; or put marks in a notebook. Do not try to remember the count; always use one of these methods or design your own method.
(2) Certain conditions affect your pace count in the field, and you must allow for them by making adjustments.
Under (2):
(a) Slopes. Your pace lengthens on a downslope and shortens on an upgrade. Keeping this in mind, if it normally takes you 120 paces to walk 100 meters, your pace count may increase to 130 or more when walking up a slope.
(b) Winds. A head wind shortens the pace and a tail wind increases it.
(c) Surfaces. Sand, gravel, mud, snow, and similar surface materials tend to shorten the pace.
(d) Elements. Falling snow, rain, or ice cause the pace to be reduced in length.
(e) Clothing. Excess clothing and boots with poor traction affect the pace length.
(f) Visibility. Poor visibility, such as in fog, rain, or darkness, will shorten your pace. Perhaps some clever person could realize that perhaps this might better be done in pace-seconds?—-please tell me you realize I’m joking. This exercise points out how poor and variable a measure the human body is for accurately determining distance, and also how easily distracted humans are. Everyone who uses a ruler, Asian, Nordic, girl, boy, woman, or man have access to the same length measure using metric. Don’t add time to your rulers. Despite what you hear, their is no “length of time.”
If you liked this essay and wish to support the work of The Metric Maven, please visit his Patreon Page and contribute. Also purchase his books about the metric system:
The first book is titled: Our Crumbling Invisible Infrastructure. It is a succinct set of essays that explain why the absence of the metric system in the US is detrimental to our personal heath and our economy. These essays are separately available for free on my website, but the book has them all in one place in print. The book may be purchased from Amazon here.
The second book is titled The Dimensions of the Cosmos. It takes the metric prefixes from yotta to Yocto and uses each metric prefix to describe a metric world. The book has a considerable number of color images to compliment the prose. It has been receiving good reviews. I think would be a great reference for US science teachers. It has a considerable number of scientific factoids and anecdotes that I believe would be of considerable educational use. It is available from Amazon here.
The third book is called Death By A Thousand Cuts, A Secret History of the Metric System in The United States. This monograph explains how we have been unable to legally deal with weights and measures in the United States from George Washington, to our current day. This book is also available on Amazon here.
