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Issues in Science > Units of measurement in pop science writing.

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message 1: by Robbower (new)

Robbower | 50 comments Does anyone else get put off by pop science writers who persist in translating common units of measurement into inane comparisons? I'm talking about things like translating micrometers into fractions of the width of a human hair, or hundreds of meters into so many stories of a building, or kilometers into the length of so many football fields. Personally, I find it confusing and distracting. Also, it opens up a whole new potential for major error. I just read a statement by a Dutch science writer who said that 27,000 light years is the equivalent of about a quarter of a trillion kilometers... six orders of magnitude off.


message 2: by Betsy, co-mod (new)

Betsy | 1668 comments Mod
Well, as a lay person, I appreciate an author trying to translate obscure measurements into something I'm more likely to understand viscerally, but they certainly ought to be accurate.


message 3: by Jim (new)

Jim (jimmaclachlan) | 629 comments Next you'll be telling me that the Millenium Falcon didn't make the Kessel run in less than twelve parsecs.
;)

I'm with Betsy, though. So long as they get it right, a good comparison creates better understanding for me. I remember the first time I read Future Shock. Toffler put modern human history into 800 sixty year lifetimes end to end, then went on to say we've only been out of the caves for 150 & 95% of all the scientists have lived during the last one. (The figures may be a bit off. It's been a long time since I last read it.) I can't really imagine or get a handle on thousands of years as well as I can hundreds of lifetimes. The impact of the number of scientists was huge as well.

Of course, fudging around around like that can also be misleading or even meaningless without being wrong, especially to a lay person without any background to properly put things into perspective. I remember a scene in "Bones" where Boothe throws out their toothbrushes because he hears that flushing the toilet with the lid open spreads millions of bacteria that will contaminate them. I won't say any more, because it's part of what made Bad Science so good & we start reading that as a group shortly.


message 4: by Angus (new)

Angus Mcfarlane | 71 comments I agree with the problem, but sympathize with the intent. With measurements I'm familiar with, microns say, I don't need the hair width comparison, but other times appreciate the effort to build the picture. Sometimes I find they don't help - x number of swimming pools or Sydney Harbours doesn't really help me understand a volume of water any more than Cubic meters (which I tend to translate into equivalent proportion of urban water supply). Nor did the use of 'half the length of Long Island turned on its side' help me understand the depth of the Witwatersrand gold mine complex - I've never been to either. Even worse for me though, is the use of imperial and non standard units - I can usually do the conversion but it takes a lot out of the read.


message 5: by Angus (new)

Angus Mcfarlane | 71 comments I agree with the problem, but sympathize with the intent. With measurements I'm familiar with, microns say, I don't need the hair width comparison, but other times appreciate the effort to build the picture. Sometimes I find they don't help - x number of swimming pools or Sydney Harbours doesn't really help me understand a volume of water any more than Cubic meters (which I tend to translate into equivalent proportion of urban water supply). Nor did the use of 'half the length of Long Island turned on its side' help me understand the depth of the Witwatersrand gold mine complex - I've never been to either. Even worse for me though, is the use of imperial and non standard units - I can usually do the conversion but it takes a lot out of the read.


message 6: by Robbower (new)

Robbower | 50 comments Jim wrote: "Next you'll be telling me that the Millenium Falcon didn't make the Kessel run in less than twelve parsecs.
;)

Well, yeah, but Han Solo was always travelling around at light speed too. So unless the galaxy far, far, away was very, very small, he was taking years just to get to the next star system.



message 7: by Robbower (new)

Robbower | 50 comments Angus wrote: "I agree with the problem, but sympathize with the intent. With measurements I'm familiar with, microns say, I don't need the hair width comparison, but other times appreciate the effort to build th..."

I especially like the comparisons that line up things end-to-end and stretch around the equator x number of times, or the stacks of dollar bills that reach to the moon.


message 8: by Robbower (new)

Robbower | 50 comments Betsy wrote: "Well, as a lay person, I appreciate an author trying to translate obscure measurements into something I'm more likely to understand viscerally, but they certainly ought to be accurate."

I agree about the obscure measurements - certainly, define them in term of meters, grams, etc. I was specifically commenting on the common ones; and rather than defining them, comparing them to inane things like soccer fields or stacks of quarters, or the weight of elephants.


message 9: by John (new)

John Austin | 74 comments I was just browsing around around and I saw this thread which was of interest to me.

Robbower, I entirely agree with you! It irritates me as well. By now we all ought to know how big a kilogramme or a metre are etc. etc.

In fact I usually turn it the other way around, perverse, though I am. For example, if I read that a pole vaulter has just leaped over a bar at 6 metres, I might later discover in the crappy newspaper the next day that this is the height of "one and a half buses".

Ah ah, I declare, a bus must be 4 metres tall! Same with elephants and tonnes. Who knows how heavy an elephant is, but if someone tells you that something weighs 5 tonnes, or the weight of "5 elephants". Wow! comes my thought, an elephant must weigh 1 tonne!


message 10: by Jim (new)

Jim (jimmaclachlan) | 629 comments I got curious about the number of chromosomes in various species & found this site with a great explanation:
http://genetics.thetech.org/ask/ask257

Not strictly units of measurement, but the analogy using piles of clothes for the amount & numbers of chromosomes & genes really helped make it easy to understand for me. Does it make any of the real biologists cringe?


message 11: by Kikyosan (new)

Kikyosan | 64 comments I hate when translators meet a rough value expressed in anglosaxon units (mile, pound, gallon etc), put it into a unit converter and then they report an absurdely precise value in the new unit. Maybe there is a reason if the original value was roughly approximated. ("maybe" is sarcastic). The results sound very ridiculous .


message 12: by Kikyosan (last edited Jun 30, 2015 12:24PM) (new)

Kikyosan | 64 comments "translators": people who write translations. Not the automatic tools.


message 13: by John (new)

John Austin | 74 comments Kikyosan,

Your comment about medieval units (because that is surely what they are, not "anglosaxon"), is apt. If you read recommendations by organisations such as the UK Metric Association, all conversions from one set of units to another should be rounded to the same precision. In any case this is good physics.

One of the reasons in the UK that people apparently "don't understand the metric system" is that they only learn to convert and use excess precision, which confuses the issue. Otherwise, dividing and multiplying by factors of 10 is childs' play! Of course some people still need a calculator for this.

In Britain, our units are baffling. People still claim to understand them, but try getting someone to tell you precisely how big an acre is, without the usual nonsense of "the size of a football field" sort of argument. I have yet to find anybody who really knows what these units are.

The USA is no better. I haven't tested them on acres. but almost nobody knows what a bushel is. Yet US industry frequently uses this medieval unit.


message 14: by Kikyosan (new)

Kikyosan | 64 comments I've always found very "ancient" (in the good acception) the actual descriptions of UK and US units. They involve body parts (feet, and every possible section of a hand) and Roman units.
(It's very interesting the way Fahrenheit set his scale for temperature: water, salt, horse blood..)
Very fascinating, but really confusing. I'm lucky with my self-explaning names of SI units :)


message 15: by John (last edited Jun 30, 2015 04:00PM) (new)

John Austin | 74 comments Kikosyan,

Yes the old "Imperial" units have long been superseded by SI, which are an elegant set of units. SI has a unit for measuring everything conceivable. The electrical units in SI are connected to the energy unit (J), without conversion factors. Imperial units don't have most of the useful units, such as electricity, so it borrows from the SI. So nations like the US and the UK are a complete mess as they sometimes use Imperial, sometimes use SI, and there are a confusing mix of awkward conversion factors.

Most people remain quite uninformed of the cleverness behind SI units. I have explained it all in my book "Measuring the World".

In a few years' time physicists expect to redefine the kilogramme. It is currently a lump of platinum/iridium but if improvements in measurements occur, then in a few years' time all our units will be "universal".

This is a remarkable intellectual achievement. For example the metre started as a length of a metal bar, then it went to a wavelength of light and now it is defined by specifying the speed of light as a fixed constant 299,792,458 m/s exactly. This means that we start by defining the second and define the metre by the distance travelled by light in 1/299792458 seconds. ALL the other units are now defined in similar vein except that the kilogramme has been stubbornly kept as a lump of metal.

That will probably change shortly by using electrical units to define the kilogramme. This is a very exciting time for metrology!


message 16: by Jim (new)

Jim (jimmaclachlan) | 629 comments I really wish we'd switch to metric. I live in the US & a few years in the Army had me dealing with metric distances with no trouble at all. It's not that hard. What is hard is jumping back & forth all the time. Like Daylight Savings time, a devil's invention if there ever was one. Some do, some don't, & many travel, so just what time is it where? I have to look it up all the time, even in the US! Ugh! Besides, I'm a morning person that lives in the far west of my time zone. It's often still light out when I'm going to bed, but always dark when I wake up.

The worst is needing 2 sets of many tools to work on my tractors, vehicles & other things. It's really infuriating to buy things that are put made in another country & put together here as it's not unusual to have to pull out both sets & then guess which to use on every nut & bolt. Ugh! There's a LOT to be said for standardization, especially now that the world has shrunk so much.


message 17: by Betsy, co-mod (new)

Betsy | 1668 comments Mod
Okay, I'll expose my ignorance. What is SI?


message 18: by John (new)

John Austin | 74 comments Betsy,

SI is "Systeme Internationale", excuse my French! It is the system based on the metre, kilogramme and second. The system is also known as MKS after the aforementioned units.

It is better than the cgs system (the system best known perhaps by Americans). SI essentially replaced cgs about 50 years ago and has the main advantage that the units are more manageable (human sized).

The point of any proper system of units is that if everything is in the same system, then the results of all calculations remain within the system without any factors, not even factors of 10. For example, suppose we have a loaded jet aircraft sitting on the runway. Its weight is, say, 100 tonnes = 100,000 kg. Suppose the engine thrust is 400 kilonewtons (kN) = 400,000 N then the acceleration is from Newton's law F = ma, a = F/m = 400,000/100,000 = 4. In SI the unit of acceleration is metres per second squared (m/s2), so the answer is 4 m/s2, compared with gravity of 9.8 m/s2. Easy!

Try doing that calculation in Imperial units or "American Standard" units! It's a nightmare, as is everything else.
In these units, engine power is in horse power not newtons which requires a conversion factor, and aircraft weights are in tons which have another conversion of 2000 or 2240 depending on which side of the Atlantic you're on.


message 19: by Kikyosan (new)

Kikyosan | 64 comments John said "For example the metre started as a length of a metal bar, then it went to a wavelength of light and now it is defined by specifying the speed of light as a fixed constant 299,792,458 m/s exactly"

When I was a child I was taught a meter was the one ten-millionth part of the distance between the north pole and the equator (that impressed me much, because as a child I couldn't imagine how they could measure a distance like that!) Then it became what you said about light.

To remain in thread, I start to understand the "football fields" method if it is used by non-SI people: they have to face so many trouble with conversions and variety of units.

however, every unit has a very empirical origin, maybe in a far future we will deal with a "FF" or "football fields" international units :D
(I hope not, I don't like football and I don't even imagine how long a football field is. Also, I am a woman whose brain is not so easy with "guess-how-much" issues)


message 20: by David (new)

David Rubenstein | 870 comments Mod
At work I find it very convenient to think in terms of the units "nautical mile" and "knot" when it comes to ship navigation. Of course then I often have to use a conversion factor to go to units of kilometers and meters per second. The reason the old units are so useful is that they relate so easily to navigation. One minute of latitude on the Earth's surface is a nautical mile and a knot is one nautical mile per hour.

However people also commonly use knots to describe a wind speed where it makes no sense to me at all.


message 21: by John (new)

John Austin | 74 comments Kikyosan,

Sorry, I forgot about the first definition of the metre, which was indeed one ten millionth part of the distance from equator to pole.

The way that one measures this is to choose a meridian, running for example through Paris and then measure 1 degree of latitude using surveying techniques. You can measure a degree of latitude by observing the angle of the sun. Later, it was discovered that the Earth wasn't spherical and so the metre definition wasn't as useful as originally thought. Hence the move to the metal bar.

This was found to have problems. The equivalent metal bar for the Imperial Yard was found to shrink (!) thus messing up the standard. The metre distance would have been determined by scratches on the metal bar. There is only a limited accuracy with which distances can be compared using this method, so moving to the wavelength standard enabled the metre to be defined to improved precision.

Initially, the metre was only known to a precision of 1 part in 10,000 - the measurement of the meridian. Moving to the bar improved eventually to 1 part in 10 million. Moving to the wavelength standard gave 10 parts in a billion and when the fixed speed of light definition was used another 2 orders of magnitude improvement occurred. Current standards rely on the the reproducibility of frequency standards so I think current standards for the metre have reached about 1 part in 10^-12, 1 part per trillion, although I'm not certain. In particular, using light beams reflected off a mirror placed on the moon, we now know that the moon is drifting outwards at the rate of 3.8 cm per year!!

Regarding football fields etc. the metre (or any other SI unit) is not going to change in magnitude. It would cost too much for industry to change over to a new set. The BIPM, is the international organisation responsible for maintaining units. Once the kg is sorted, all our units will be derivable from "universal" quantities, based on just 7 numbers. These include the velocity of light, 299792458 m/s.
Temperature will no longer exist as you know it (fixed points using water etc.), which is cumbersome in practice. Instead temperature will be defined by the Boltzmann constant which is currently 13806488x10^-23 J/K. The revision of the kg will be defined by the Planck constant, currently 662606957x10^-34 Js. The change will only take place once the Planck constant is known to the same precision as comparison of weights with the international prototype kilogramme (several tens of a part per billion).

And do you know the beauty of all this? None of the public is any wiser for this deeply fundamental change to our unit systems. The elegance of the 7 constants to define everything seems to me to be one of the most understated intellectual achievements of mankind.

There is an irony in that US and UK scientists have played prominent roles in the past and are at the forefront of the kilogramme revolution.

By the way, the Imperial units lost their independence about 50 years ago, if not more. In other words, there is no standard yard any more, nor is there a standard pound mass. Instead everything is defined in terms of SI units. So, for example, 1 inch = 2.54 cm exactly.


message 22: by John (new)

John Austin | 74 comments David,

The point about a coordinated unit system is that not everything is perfect for every individual. Nonetheless, the use of a consistent set pays dividends overall.

By using knots and nautical miles you actually give yourself a slight problem as the Earth is not spherical. In any case, a nautical mile is now defined as 1852 m exactly. The fact that you use it with the old definition (I presume) worries me a bit and suggests that your calculations may not be as precise as you think.

In this day and age of GPS I don't see the point of using knots or NM. Regarding the wind speed, there is in principle just as many reasons for using it. Wind speed used to be a significant factor in navigation and remains so for aircraft for example crossing the Atlantic. Frequently jets seek out the jet stream and that can give them a boost of 100 kts+.

A better policy overall is for information to start in the proper SI unit --- m/s for speed --- and use a proper distance measurement in m to find times in seconds. Then do the conversion to calculate travel times in hours or whatever.

I think humans will be extinct before that happens, sadly.


message 23: by John (new)

John Austin | 74 comments Jim,

You're quite right: it's the mixture of units that's confusing and unnecessary. Industry would also benefit financially from using a world standard, yet some companies persist in using the old units. I can't help thinking that they persist out of a sense of patriotism. The units "were not designed here" so can't be any good! That applies to the UK and US.

Nothing could be further from the truth. A lot of SI units are named after British scientists and a few after American scientists. The two countries continue to do great work.

In Britain, the common folk have a natural dislike of metric units partly because they erroneously think they're imposed from the EU. This is a somewhat undemocratic organisation so people are naturally suspicious. However Brussels knows that this would be opposed by many in Britain, so it leaves well alone. The one time that the EU could do something useful: insist our roads go metric, it leaves us alone. Of course there would be outrage for a few years, but when the old fuddy duddies die off, people will wonder what the fuss was about.

Why can't we as citizens of the world, accept that the French had a damn good idea and adopt it? Actually most of them do, its just 400 million people that don't, out of a population of 7 billion. We have no problems in using the internet, which was also a good idea.


message 24: by Jim (last edited Jul 01, 2015 06:54AM) (new)

Jim (jimmaclachlan) | 629 comments Scientific precision is a good reason for the metric system, but imprecise humans have a lot of reasons for not adopting it. The world rarely works with precision. I'm not a sailor, but I'd imagine the sea example would provide plenty of reasons for keeping the old units. For instance, GPS in the real world isn't as precise nor ubiquitous as some think & a sailor often needs to guesstimate when instruments fail. I know enough about the sea to know that it's really big & eats man made objects like candy, especially electronics.

In woodworking, adopting the metric system in this country is going to be a mess & I'm not sure it would be for the better. Not only do we all have a lot of money wrapped up in SAE tools, but wood is processed, described, & planned for using SAE measurements. They often work quite elegantly together, better than the metric system in many cases.

While I do have some metric tools, the measurements are generally more of a pain even when working from the ground up even when everything is using manufactured wood. That's been made to metric measurements for the past few decades & it's been a mess. The old nominal sizes based on inches were generally converted at the rate of 25 mm to the inch. That means 1/4" plywood should be 6.25mm, but generally isn't, often by 1mm. Ugh.

Older methods are great as a backup & reality check. Sometimes they're even better, especially when it comes to art & design. We're hardwired to like some forms better than others & we tend to lose sight of this. Our ancestors figured much of this out or we have in retrospect. For instance, I recently read a book on design using constructions (compass & straight edge) which the SAE measurements work with admirably for half, quarters, eighths, & so on.

For some projects, I don't bother measuring with a ruler, just size according to the base & construct from there. The base is often just a board I split out & finished to a pleasing dimension. Any measurements are kept on a measuring stick unique to that project. A ruler would just be confusing. Real old school, but the results are far more pleasing than cold, scientific precision.


message 25: by Jim (new)

Jim (jimmaclachlan) | 629 comments John wrote: "Jim,
You're quite right: it's the mixture of units that's confusing and unnecessary. Industry would also benefit financially from using a world standard, yet some companies persist in using the ol..."


I think you missed the point. Disregarding retooling, SAE measurements are actually easier to use in some cases. Often figuring 1/8th of a metric unit is much harder than it is in SAE. There are often design reasons to that sort of math.


message 26: by John (new)

John Austin | 74 comments Jim,

I think most people (95%) of the world have no trouble using the metric system for all their needs. There is no reason that UK and US citizens should be otherwise, imprecise people or not. you illustrate problems how not to go metric: namely by converting from Imperial and rounding (25 mm). Industry needs to work with one set of units, that's all. Using fractions (a half, quarter etc.) is also part of the problem. We have 10 fingers, use decimals!


message 27: by Jim (new)

Jim (jimmaclachlan) | 629 comments John wrote: "...We have 10 fingers, use decimals! "

Again, you're missing the point. The real world isn't based on our ten fingers or completely arbitrary rules. There are natural relationships that can work for us.
- I work with computers & generally use hex because it's easier than binary or decimal.
- When I work with wood & design, fractions are usually far easier than decimal or I skip traditional measuring entirely.

Metric is a pretty good & fairly logical system, but we're people. One size rarely fits all.


message 28: by John (new)

John Austin | 74 comments Jim,

I haven't missed the point. Ultimately, your comments indicate why we're in a mess over units and measurements, because everyone wants to use their own pet units instead of broadly useful ones. You seem to want to use inches and fractions for wood (or close equivalents) whereas I believe that decimals would serve your purpose just as well, if business supplied materials in truly metric format.

I know one size doesn't fit all, including the metric system, but it's the best that anyone has come up with. What do you want to do, use lots of different sets of units for each profession? In Britain we have been celebrating the 800th anniversary of the Magna Carta. This is equivalent to the US constitution.

One of its clauses states that the purpose of government was to establish "one set of measurements throughout the land". Alas, there are now TWO such competing systems, so our government over the last century has been in breach of our "constitution".

I don't think anyone is suggesting that you stop using binary or hex. However, you should stop calling kB kilobytes. This is confusing, although everyone seems to do it. One kB is of course 2^10 or 1024, ie, not 1000. The recommendation of the SI is that 1024 be called kiB (kibibytes), your GB should be GiB (Gibibytes) etc. It is just this sort of confusion that can cause serious problems. I have seen the recommended notation in a few places, but it's not common enough.


message 29: by Jim (new)

Jim (jimmaclachlan) | 629 comments I've already said I wish the US would adopt metric units, but was pointing out where it would be a mess & why it may never be adopted in some instances. Your 'belief' that a base 10 measuring system is better in woodworking is at odds with my working knowledge & decades of experience. You seem to have lost sight of both points in your zeal.

As for changing kb, I don't really care, but I doubt it will catch on with the marketing folks. They can't tell a bit from a byte, anyway. Otherwise, we deal with it handily enough since the problem only arises when we have to deal with it in decimal rather than hex or binary. That generally only comes up with imprecise humans or interfaces that are dumbed down for them.

Not being precise might actually be better if we ever need another base besides 2. Might need to tighten the language then, too. I don't know. The Russians tried a base 5 decades ago but it didn't pan out & is largely forgotten. Might work when with quantum computing, though.


message 30: by Nancy (new)

Nancy Mills (nancyfaym) | 403 comments I can't really contribute much to this thread but I'm loving it!
ok folks, what about time measurements? Why are there 24 hours in a day and 60 minutes in an hour and 60 seconds in a minute? And The clock only has 12 numbers thus goes round twice a day, unless you are military. Why not 10 hours divided into 10 decahours divided into 20 centihours... or probably more useful to scientists, so many seconds, so many kiloseconds etc.
I also find it unsatisfying that God saw fit to give us a 365-odd day orbit which would make it hard to sensibly divide this into 10s. best I could do is 10 36s with 5 days off for Christmas or whatever holidays you prefer. with the leap days and seconds all thrown in at the end too.
Why with all this wonderful metric conversion (which truly DOES make it much easier for those of us with 10 fingers) have they not tampered with the clock?


message 31: by Jim (new)

Jim (jimmaclachlan) | 629 comments I was discussing this with my SIL & we decided it boiled down to proportions. Some things just naturally break up into different base proportions than others. I don't know enough to tell where & why in all cases, but I suspect we're stuck with some because they naturally work better.

I don't see how we'd break up years into any sort of base 10 days at all. The globe spins about just about 365.25 each year. Not something we can change or break up much better naturally. A day of 10 hours of 100 minutes with 1000 seconds (or something like that) seems likely to work on the face of it, but changing it would certainly have far reaching effects. We'd have to rewrite most sciences from the basement on up whenever they relied upon time. Still, why did we break it up this way at all?

How would that work with geometry? Why do we split a circle into 360 degrees? We could break it into base 10 units, but what would that do to geometric proofs? I don't know much geometry, but I use a fair amount woodworking. Constructions wouldn't change, but instead of a 90 degree angle being square, we'd have 25 degrees if there were 100 in a circle. Constructed bisections & trisections would be decidedly weirdly numbered. 12.5 instead of 45 doesn't seem bad, but 8-1/3 degrees instead of 30 doesn't work well. Pretty complicated & not as exact, I think. What happens to pi? The relationship hasn't changed - it's still the circumference divided by the radius. I wonder what would happen to sea navigation which is based heavily on geometry?

Seems like a real can of worms. I wonder if it would be for the better. Probably changing time if we become a space based race, but I doubt geometry would benefit.


message 32: by Kikyosan (new)

Kikyosan | 64 comments Babylonians decided for 12 and 360. Their numeral system was sexagesimal (base 60).
"12" comes from the Moon. 12 "moons" per year, so it was a key number for Babylonians, who decided to split the day into 12. And night too. Then a lot of corrections occurred to improve this division.

Every month has almost 30 days, and 12x30=360. It could be the reason why Babylonians used 360 as the measure of a circle (I imagine they knew that a real year was made up of 365 days, but maybe this could be a practical approximation to measure angles). Also, like 60, it is a very practical number as it has a lot of divisors, so it can be split in a lot of different way without using fractions.

These are hypotesis, but they make sense.

However, when the French created the decimal metric system they also tried to impose a different division of time and calendar (the "new time" of the French Revolution). A year was divided into 12 months (with very bucolic names), every months was divided into 30 days. So there were 5 extra days for vacations at the end of the year.
Each month was divided into 3 decades of 10 days. Each day was divided into 10 hours, each hour into 100 minutes, each minutes in 100 seconds.
This system last few years, it was not so natural. But their decimal metric revolution won.


message 33: by Jim (new)

Jim (jimmaclachlan) | 629 comments Interesting. Thanks, Kikyosan. Wow. I had no idea it went back that far & hadn't thought about the moon at all. That sort of makes sense, but I thought there were 13 moons each year. Isn't that how we get a blue moon - 2 in a month? 28 day period, right?


message 34: by Kikyosan (new)

Kikyosan | 64 comments Yes and no. :)
I mean, the moon completes its revolution around the Earth in 27 days (and few hours). But in the meanwhile, the Earth has done almost 1/12 of its revolution around the Sun. So, it takes other 2 days to the moon to return in the initial position, with respect to the Sun and Earth. And here are the 29-30 days (infact between 2 full moons there are 29 days, not 27 or 28) And as our "official" months are made up of 30-31 days, lunar months (29-30, technically called "synodic") are a little shorter. So it happens to have a full moon at the very start of a month and a second one at the very end.

And you can understand why the "commonly adopted" lunar month was made up of 29-30. Ancient people counted the days between two identical positions of the moon with respect to the sun and the earth.

I don't know if this sounds clear, I have to admit that my Science teacher was very able to make things like these very easy. Astronomical Geography is not my thing. Some days ago I was studying birds' navigation systems, included a very developed inner compass based on the sun, its azimuth and its projections on the horizon. I was literally going crazy. My brain region assigned to spacial positioning must be very poor. :)


message 35: by Jim (new)

Jim (jimmaclachlan) | 629 comments Ah! I hadn't thought about that, but it makes perfect sense now that you explain it. I'm also quite abashed that I didn't know that. For all that I like space & watch the stars for a minute before I get in my car to go to work most mornings, I've never studied astronomy or actually counted days. Thanks.


message 36: by Kikyosan (new)

Kikyosan | 64 comments Thanks to you :)
It would be interesting to study if lunar months were adopted indipendently by different ancient people who never got in touch. Or their alternative solutions. I suppose that lunar and solar recurrence was the most natural way to divide time into. Animals use the sun too, most of them have a 24h inner time. It's a very interesting field of animal behaviour and physiology.


message 37: by John (last edited Jul 04, 2015 04:18AM) (new)

John Austin | 74 comments I've been a bit out of touch the last few days, so not contributed, but I thought I would just add some comments now.

Regarding the length of the year, this obviously a largely random number of times that the Earth rotates on its axis, and it is up to us to make our calendars fit. We are using the Gregorian calendar invented by Pope Gregory, based in part on the previous roman calendar.

The Roman (Julian) calendar was quite political with various months named after various generals with different lengths according to their self professed importance. The total year length was also not right at 365.25 days, i.e., the calendar we know plus a leap year every 4 years.

Over the centuries, the Julian calendar drifted by about 10 days or so away from the seasons. Pope Gregory fixed that so that leap years occurred less frequently, equivalent to a year length of 365.2425, close to the actual length of 365.2422 if my memory serves me correctly. This means that the current calendar will drift away from the seasons by only 3 days after 10,000 years.

Pope Gregory could have fixed the calendar and made it a lot simpler but he didn't have the smarts to do so. One proposed calendar is the "World Calendar" which has 4 equal quarters of 13 weeks plus 1 day. Each quarter consists of 3 30-day months plus 1 day. The leap days are inserted when needed at the end of the year. The days at the end of the year don't get a name but the others do (Monday, etc. as now). The "World Calendar" has many benefits, including the first day of each month being fixed.

Although this is a much better calendar than the Gregorian one, I think there is little hope that we will adopt it or anything like it.

Overall, it makes no sense to go metric for time. Our current system of seconds, minutes etc. seems to work fine.
I agree that originally months were probably vaguely based on the moon. It's also interesting that one week corresponds approximately to the duration of a phase of the moon. I don't know if this ever had a bearing on the design of the calendar.


message 38: by Kikyosan (new)

Kikyosan | 64 comments John wrote: "The Roman (Julian) calendar was quite political with various months named after various generals with different lengths according to their self professed importance. The total year length was also not right at 365.25 days, i.e., the calendar we know plus a leap year every 4 years."

This is quite uncorrect.
The Julian calendar was not political and the months were named after gods (january: Janus, march:Mars, june:Juno) or bucolic events (february, april, I don't remember the details) or the position in the year (quintile:5, sestile:6, september:7, october:8, november:9, december:10) since March was the first month before Julian calendar. Then Quintile was named July after Julius Caesar (not by himself), and August was named after Emperor Augustus (by Senate). So, only two months were actually named after emperors, and only one (August) was gifted with an additional day (stolen from February) to honorate Augustus. Other months were almost alternately of 30 and 31, but when August was elongated, some adjustements were made.
Then, other names alterations were never considered, even if some emperors tried to impose his own month.

As you say, Julian Calendar was exactly 365.25 long, due to the excessive amount of leap years, but the big shift was caused mostly by a confused application of these leap years.


message 39: by Jim (new)

Jim (jimmaclachlan) | 629 comments Kikyosan wrote: "... Animals use the sun too, most of them have a 24h inner time. It's a very interesting field of animal behaviour and physiology."

I'm quite aware of that! I was born on & own a small farm & the animals are no more impressed by Daylight Savings Time than I am. Really screws us up.


message 40: by John (new)

John Robinson | 3 comments Nancy wrote: "I can't really contribute much to this thread but I'm loving it!
ok folks, what about time measurements? Why are there 24 hours in a day and 60 minutes in an hour and 60 seconds in a minute? And T..."


Jim wrote: "I was discussing this with my SIL & we decided it boiled down to proportions. Some things just naturally break up into different base proportions than others. I don't know enough to tell where & ..."

Isaac Asimov has written some wonderful things about this topic, even proposing his own ideas for different calendars. His books are still widely available as used copies. Highly recommended. He is a continually useful resource.


message 41: by Jim (new)

Jim (jimmaclachlan) | 629 comments I have Realm Of Measure: From The Yardstick To The Theory Of Relativity, but probably haven't read it in a decade or more. As I recall, it was very good, yet's it's a super thin volume. Probably time to reread it.


message 42: by Jim (new)

Jim (jimmaclachlan) | 629 comments I cursed not using the metric system as I was fiddling with quantities that swapped between dry & wet measures from pounds down to tablespoons with dilutions in between.

One of my many interests is knitting & crocheting. That led to building my own spinning wheel & now into dyeing the yarn I spin. Dyes vary a lot depending on the color & material used. I just tried my first batch using the stove top method for acid dyes as 'explained' here:
http://www.jacquardproducts.com/asset...
The above is only 2 pages long & only the first paragraphs on each page apply. If you read them, you'll see that there is a lot left to the imagination. I did some more reading in a Google+ group before trying it, too.

The dye comes as a powder in 2.5oz lots. This needs to be put into a solution first, so I bought some 8oz containers, but found some colors didn't dissolve well unless I went up to 12oz, so I did for all of them to keep the same proportions. That leaves room in the containers to shake them well before using, too.

Then I had to look at the chart to see the recommended amount of dye to use per pound since some, like the 602-yellow need far less than others like the 632-chestnut. Mind you, I needed to figure out how much powdered dye was in each ounce of my liquid & some skeins are individual threads, so only 2 to 3 oz each - a small portion of a pound. The icing on the cake is that the amount of water used to soak the thread is 'enough'. Oy!

I spent some time figuring it all out & then wound up using 3 tablespoons of the 602-yellow. I'm not really sure how I arrived at that figure any more, but it came out great, so I used that as a baseline. According to the chart on page 2 of the above document, the 638-gray was supposed to use the same amount, but I had to dye it twice & I used twice as much dye the second time. It's OK, but still not as gray as I would have liked. Both the 622-blue & 629-emerald came out bright with just 3 tablespoons, even though they were supposed to need 4 - 6 times as much!

Anyway, metric units would have made all of this a LOT easier. 16 oz to a pound with 3 tablespoons per oz in a dilution of 2.5 oz to 12 oz just made my head hurt. I've decided that dyeing things is more a matter of luck & experience than science. I won't rule out magic yet, either.
;)


message 43: by Kikyosan (new)

Kikyosan | 64 comments Last week I watched a movie where a babysitter was teaching a boy to make conversions with milk and cereals quantities. I immediately thought about this post. And I realized that Italian children are quite lucky: no conversions and no spelling problems! :)

however, your dying thing sounds like alchemy :) practice is always needed (even when I prepare a cake, following an apparently perfect recipe written in grams and liters!!)


message 44: by John (new)

John Austin | 74 comments Jim,

You mention difficulties with measurements associated with dry/liquid measures. This is of course a problem introduced by medieval England but you poor suckers in the USA continue to confuse yourselves! In the UK, we no longer distinguish between dry and liquid measures. Although we are officially metric, there are die hards and so-called traditionalists that like to make things difficult for themselves by using medieval units. The trouble is that they continue to poison our young. At school they measure themselves in metres and kilogrammes but then convert to feet and inches and stones and pounds outside school.

This is encouraged by ignorant journalists. I read yesterday that space debris is moving at 28163 km/h, an overly precise figure I thought until you realise that it is an exact conversion of 17500 miles/h. That is another mistake that the english-speaking world tend to do: when converting from or to medieval units you have to keep the same precision. Faced with a number like 28163, is it any wonder people prefer the alternative 17500? Really, they should use 28200 km/h, or better still, 28,000.

I know my weight and height in metres and kilogrammes but very few British people know these numbers. If you're male in Britain, you can pretend that you're tall if you have reached the towering height of 6 ft. Many people are proud of that and even quote their height to a quarter inch just to get over the magic number. However, it is only 1.83 m and with improved nutrition and so on, that is getting to be a very ordinary height for the current generation.


message 45: by John (new)

John Austin | 74 comments Kikyosan,

Your comment about Italian children was apt. By using decent, properly designed units Italians can free up their minds for the proper business. It means for example that they likely have much more opportunity for mental arithmetic. UK and US children by contrast have to struggle with awful units, and the average child gives up. It is probably no coincidence that despite our relatively high wealth (particularly USA) the average child is hopeless at maths.

It is the end of the national exam period and the results are coming out. The kiddies have been complaining about how difficult their maths exams were. It makes me weep.

Of course intelligent people don't have anything to worry about as they can switch relatively easily from one system to the next.


message 46: by Kikyosan (new)

Kikyosan | 64 comments When I was at school I hated Fahrenheit degrees. I found them so complicate to convert because they had both a different zero point and a different unit extension. And they were based on the temperature on horse blood and salty water (or something like that).Weird. I still don't like them because when I read "oh it's 51F" I can't immediately understand if it is hot or cold.

another example of bad conversions in a (serious) US textbook: megafauna refers to animals beyond 44kg. I can hardly image biologists weighing animals to assess if they are 43 or 44 kg... including extinct species. if you set a so precise threshold, it means that a single kilo makes the difference. but it doesn't if you talk about a rough 20 pounds threshold. They wanted to adopt metric system and it's ok (it's a scientific book) but they should have included the original threshold to make the point.


message 47: by Jim (new)

Jim (jimmaclachlan) | 629 comments John wrote: "Jim, You mention difficulties with measurements associated with dry/liquid measures. ..."

That's exactly the point I was making with a real world example. Didn't I make that clear? I know you want the world to go metric. Most of us do. No need to be redundant about it, though.

I agree with you on the overly precise numbers. It is stupid. 28K would have been just fine in that example & I really appreciate scientific notation when appropriate, but it often depends on the context. Writers are trying for emotional impact, just like the person who wants to be over 6'. While I liked Heinlein's Juveniles, I detested the way he wrote numbers at times, 'a hundred million billion thousand...' or something like that. Yuck.

John wrote: "UK and US children by contrast have to struggle with awful units, and the average child gives up."

By this reasoning, we wouldn't read or be able to spell, either. While I can't make a great case for most people being able to do either, I don't think it's quite as simple as that. A lot has to do with how our school systems teach.

John wrote: "Of course intelligent people don't have anything to worry about as they can switch relatively easily from one system to the next."

Perhaps on paper, but there are a lot of practical measurements that are far more difficult for people in everyday life, especially at first & when they have to deal with both. We estimate units all the time & until a person gets a 'feel' for them, communication with others & every day chores can be incredibly frustrating.

For instance, my wife & I are used to pacing out spacing for jumps & dressage points. We've done it for enough years that we can get them set pretty close by yards, but meters is a lot tougher, especially for my wife. I have to lengthen my stride a little more, but she has to take 2 shorter steps & it really messes things up.

I also think it has a lot less to do with intelligence than you seem to think. (Your statement comes across as incredibly pompous & elitist, BTW.) When I was in the Army, we all had to learn to use metric & there wasn't any correlation with intelligence for the proper estimation of distances or speed in the new system. Some people got it, others never seemed to. I don't know why, but neither intelligence nor imagination seemed to be a determining factor from what I could observe.


message 48: by John (new)

John Austin | 74 comments Jim,

I was just agreeing with you. Sorry if I am too loquacious for your taste.

By the way, I'd be surprised if your pace was really 1 yard. The roman mile, which is estimated at 1480 m was 1000 "paces" or 2000 paces in our nomenclature, suggesting the Romans had a pace length of 74 cm. I'm an ex-athlete and interested in body measurements. when I was in my 20s my pace walking length was also about 75 cm, somewhat less than the 91 cm in a yard. I'm average height (1.72 m), although that average is going up. So you would need to be above average leg length (read height) to have a pace of 1 yard. I would estimate your height would need to be about 1.72x91.4/75 ~ 2.10 m. Or almost 7 feet. Don't forget that your strict pace length is heal to heal not heal to toe. If you used the latter, then that would explain why your pace was 1 yard. But it's not the sort of measure that can usefully pace out a length of track.

Kikyosan,

I can understand your distaste for Fahrenheit units which although not of that historical era, seems to be medieval in spirit because of its poor design and documentation.

Regarding megafauna, are you sure the boundary is at 44 kg and not that magical number 45.4 kg? This is of course 100 lb near enough. In fact I've just checked Wikipedia and they indeed quote 45 kg or 100 kg as two different thresholds. Presumably US books like to use the 45.4 kg threshold.


message 49: by Kikyosan (new)

Kikyosan | 64 comments John wrote: "Regarding megafauna, are you sure the boundary is at 44 kg and not that magical number 45.4 kg? This is of course 100 lb near enough."

I'm sure because I've read "44kg" on my essential textbook of Conservation Biology (two textbooks, indeed, and a couple of scientific papers). "45kg" would be more reasonable as threshold, but it is 44kg.

I'm starting to think it's a rough conversion made in some pioneer article (maybe Martin, 1984) about the topic (Pleistocene extinctions driven by human overexploitation) and commonly used as it was, without corrections.

However, we're biologists and not chemists, so 45.4 would be much more unreasonable than 44, because it is just a indicative threshold for big size animals, not lab quantities. Too precise for its use. For this reason I think it should be 45kg, or better 100 lbs (with its conversion to kg in brackets).
I think it sounds more practical because 45.4 and 44 assume a very little approximation, rather than 45 or 100.

In my previous post I wrote "20pounds" instead of "100". But it was a typo, of course.


message 50: by John (new)

John Austin | 74 comments Kikyosan,

I don't entirely understand your argument or that of biology in general.

The first point to make is that this is science not stamp collecting. The language of science is precise and uses the proper tools, which for measurement is internationally agreed as the metric system.

The second point is that the idea of megafauna, as I see it, from Wikipedia and so on, is that this refers to creatures bigger than us. I know some people are over 100 kg but they're not typical. The average human is around 70 kg. So it makes no sense to me to put the limit at 100 lb.

However, it seems that some people do, and Wikipedia give academic references from 1991 and 2002. It would seem that if scientists use the lower limit, which seems questionable to me, then they must be using 100 lb, not 43, not 44, not 45, but 45.4 kg. It probably doesn't make any difference, but science is like that: a definition is a definition and the number has to be explicit. So there is obviously some difference in definitions here with the works you are thinking of.

Personally, I think that it is absurd. Biologists need to make up their mind what a megafauna is. The 100 kg definition seems far better to me, and that has its academic adherents too, according to Wikipedia.

As non experts we can't really decide the numbers for them. It's a bit like the public getting upset when Pluto is no longer described as a planet. It's science that decides not the rest of us.

Have you heard the one about the leap second?

The authorities keep them quiet, but every now and then a second has been added to our calendars. Why? We don't get to choose.


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