kw: observations, generated images, simulated intelligence, hallucinations
This is about 15% of the total image.
Showing posts with label observations. Show all posts
Showing posts with label observations. Show all posts
Thursday, May 30, 2024
A Stable Diffusion glitch
Friday, February 01, 2019
Snowflake specs
kw: observations, convolution, novelty glasses
Someone gave me a pair of "Snowflake Glasses" as a gag gift. Here is how they look. It is kind of intriguing. There are apparently many of these with different light effects.
I could see that, whatever they did, it would be a diffraction phenomenon. The purple color hints that they use an Ozalid process to make these. That makes sense, because it is capable of very high resolution, and is used for cheap microfilm. I didn't try these while there were Christmas lights up, so when I did, I first looked at the sodium-mercury street light. A very pretty snowflake! You can see a dimmer one radiating from the reflection on the right.
I noticed a little red-green fringing, which I would expect from a diffraction effect. So I decided to try a more broad-spectrum light, as seen next.
This is the light on a neighbor's house. It shines at a side yard. The color fringing is more evident. Each wavelength is diffracted a different amount, with red moving furthest because its wavelength is the longest.
I just had to see what the pattern looked like under a microscope. That's next.
Diffraction bends light both ways, so only three pattern orientations are needed to make the hexagonal star. This pattern is called a convolution. It is the mathematical inverse of the star pattern that we see when we look through it. The oval with "snow090" is an identifier. The ovals are spaced far apart, so they don't diffract enough light to be visible, and they do it at a very low angle.
The total pattern is made up of tiles that look like they are about 2"x2" in this image. They are small enough that several of them "fit" in the beam of light that enters the pupil of your eye. Thus, no matter what portion of the specs you look through, you see the intended snowflake.
I am not sure of the magnification here. I was using my inspection microscope at 20x, but this is cropped from the middle of a bigger image, so perhaps it is around 50x.
Just for the record, it would be possible to produce such glasses that select just a few light colors (red, green and blue, for example) and diffract them separately so that they all make the same size snowflake, and there are no color fringes. But it has to be done using a different method, and the cost would be much greater. These are intended for looking at Christmas lights, which are single-color.
Someone gave me a pair of "Snowflake Glasses" as a gag gift. Here is how they look. It is kind of intriguing. There are apparently many of these with different light effects.
I noticed a little red-green fringing, which I would expect from a diffraction effect. So I decided to try a more broad-spectrum light, as seen next.
I just had to see what the pattern looked like under a microscope. That's next.
The total pattern is made up of tiles that look like they are about 2"x2" in this image. They are small enough that several of them "fit" in the beam of light that enters the pupil of your eye. Thus, no matter what portion of the specs you look through, you see the intended snowflake.
I am not sure of the magnification here. I was using my inspection microscope at 20x, but this is cropped from the middle of a bigger image, so perhaps it is around 50x.
Just for the record, it would be possible to produce such glasses that select just a few light colors (red, green and blue, for example) and diffract them separately so that they all make the same size snowflake, and there are no color fringes. But it has to be done using a different method, and the cost would be much greater. These are intended for looking at Christmas lights, which are single-color.
Monday, December 03, 2012
Women in combat
kw: opinion, observations, military service
A purportedly legal case is wending its way through the courts, and there is a strangely muted debate going on, regarding women in combat. I have instinctively rejected the thought of women serving in active combat, but have wondered how to explain it. Science Fiction writer Robert Heinlein supplied the right words, some forty years ago. As found in this PDF file, Heinlein, a naval officer, delivered the James Forrestal Memorial Lecture to the Brigade of Midshipmen in April 1973. The first half of his remarks concern how to write fiction and get paid for it. Then he went on to ask the audience, "Why are you here?"
In 1973, patriotism was unpopular. It is even less popular today. Heinlein described how to find a troop of baboons on the African veldt: don't look on the ground, but look for a lone baboon up a tree. That is the sentinel of a troop, invariably a young male. Why is he there? He is a lookout for predators, primarily leopards. His role is patriotic. Should he spot a leopard he can warn the others in time for them to take to the trees, where they have a chance of avoiding or fighting off a leopard. Every couple of hours a different young male is sent up the tree to relieve the first, who can then forage for food.
Heinlein discussed the morality of fighting. If you are attacked, you fight for your life. If you aren't willing to defend yourself, you are a detriment to the species. You will soon die and your "morality" in other regards will not matter at all. The attacker is immoral; the defender is moral. Then, at the next level, will you defend your family members? To do so is moral. To fail to do so leads to extinction of your family. To cut this discursion short: will you fight for your city, state or nation? To do so is moral. Heinlein then recalls the Navy's basic motto of patriotism: "Save women and children first."
Why is this more moral than other possible choices? Men are expendable. Women and children are not, if there is to be a future for the group, whether it is a family or a nation or a species, including Homo sapiens. In the ultimate "Adam" fantasy, one man can impregnate a nearly unlimited number of women. But one woman cannot bear any great number of children. Simply compare two scenarios:
This is not to say that women are poor fighters. I know a number of women who are stronger, faster and smarter than I am, and I am no weak man. But they can bear children, and I cannot. However, let me quote Heinlein's key sentence: "Every human culture is based on 'Women and children first'—and any attempt to do it any other way leads quickly to extinction." For this reason, and this reason alone, allowing women in combat is a morally repugnant idea and ought to be rejected in the most definite manner.
A purportedly legal case is wending its way through the courts, and there is a strangely muted debate going on, regarding women in combat. I have instinctively rejected the thought of women serving in active combat, but have wondered how to explain it. Science Fiction writer Robert Heinlein supplied the right words, some forty years ago. As found in this PDF file, Heinlein, a naval officer, delivered the James Forrestal Memorial Lecture to the Brigade of Midshipmen in April 1973. The first half of his remarks concern how to write fiction and get paid for it. Then he went on to ask the audience, "Why are you here?"
In 1973, patriotism was unpopular. It is even less popular today. Heinlein described how to find a troop of baboons on the African veldt: don't look on the ground, but look for a lone baboon up a tree. That is the sentinel of a troop, invariably a young male. Why is he there? He is a lookout for predators, primarily leopards. His role is patriotic. Should he spot a leopard he can warn the others in time for them to take to the trees, where they have a chance of avoiding or fighting off a leopard. Every couple of hours a different young male is sent up the tree to relieve the first, who can then forage for food.
Heinlein discussed the morality of fighting. If you are attacked, you fight for your life. If you aren't willing to defend yourself, you are a detriment to the species. You will soon die and your "morality" in other regards will not matter at all. The attacker is immoral; the defender is moral. Then, at the next level, will you defend your family members? To do so is moral. To fail to do so leads to extinction of your family. To cut this discursion short: will you fight for your city, state or nation? To do so is moral. Heinlein then recalls the Navy's basic motto of patriotism: "Save women and children first."
Why is this more moral than other possible choices? Men are expendable. Women and children are not, if there is to be a future for the group, whether it is a family or a nation or a species, including Homo sapiens. In the ultimate "Adam" fantasy, one man can impregnate a nearly unlimited number of women. But one woman cannot bear any great number of children. Simply compare two scenarios:
- A terrible disaster has left one man alive, and 100 women.
- A terrible disaster has left one woman alive, and 100 men.
This is not to say that women are poor fighters. I know a number of women who are stronger, faster and smarter than I am, and I am no weak man. But they can bear children, and I cannot. However, let me quote Heinlein's key sentence: "Every human culture is based on 'Women and children first'—and any attempt to do it any other way leads quickly to extinction." For this reason, and this reason alone, allowing women in combat is a morally repugnant idea and ought to be rejected in the most definite manner.
Wednesday, October 31, 2012
Where hydrogen is consumed
kw: observations, solar physics
Immediately after reviewing the prior book this morning, I began reading 2132 by Kim Stanley Robinson. It is big, more than 560 pages, so it will take a while, even at my normal breakneck reading pace. Right on page three, I saw this lovely bit of prose, describing the view from Mercury:
Mercury intercepts about 440 trillionths of this energy on average, and at perihelion its subsolar point can reach 700 K (about 430°C or 800°F). Earth actually intercepts slightly more solar energy, on average, but spreads it out over a body having nearly 7 times the surface area. If Earth were airless like the moon, its subsolar point would reach 390 K (about 115°C or 240°F).
Immediately after reviewing the prior book this morning, I began reading 2132 by Kim Stanley Robinson. It is big, more than 560 pages, so it will take a while, even at my normal breakneck reading pace. Right on page three, I saw this lovely bit of prose, describing the view from Mercury:
"[…look] at the sun's photosphere, and even magnify your view of it, until the burning tops of the convection cells are revealed in their squiggling thousands, each a thunderhead of fire burning furiously, all together torching five million tons of hydrogen a second—at which rate the star will burn another four billion years."I really like Robinson's writing, and this is a nice image, but not entirely correct. The solar spicules do look like flames, but the "torching" is going on almost 700,000 km deeper, where the temperature is some 15 million K and the pressure is unimaginable. The convection cells simply bring the heat up from below to a level from which it can radiate into space.
Mercury intercepts about 440 trillionths of this energy on average, and at perihelion its subsolar point can reach 700 K (about 430°C or 800°F). Earth actually intercepts slightly more solar energy, on average, but spreads it out over a body having nearly 7 times the surface area. If Earth were airless like the moon, its subsolar point would reach 390 K (about 115°C or 240°F).
Saturday, July 28, 2012
UV paper
kw: observations, fluorescence
I got a check in the mail yesterday, one of those rather official looking ones. On the back, in barely-visible blue ink, where you are supposed to endorse it, it states that security features include a diamond pattern visible when viewed at a low angle, and "invisible fibers". I tried looking at a low angle, and I could indeed just barely see some letters in a diamond pattern. The text also warns not to accept a check that lacks these features. I reckoned that the bank needs to have a way to see the "invisible fibers", so they must be fluorescent, visible by ultraviolet illumination.
Of course, being a rock hound, I have a short wave UV light. Sure enough, as this image shows, the words "Original Document" are there, as are scattered fibers that glow bright blue. Those must be the "invisible fibers".
A note about UV wavelengths. Until recently, all UV sources were mercury vapor tubes with filters. An ordinary "black light" tube such as those used in rock concerts is long wave UV, at a wavelength of 365nm, one of the strong "lines" in the mercury spectrum.
Visible light is officially in the range 400-700nm, though most people can see a little beyond these limits if the source is bright enough. In particular, the purple glow you see when you look at a black light tube is the 365nm line, plus fluorescence in the range 360-380nm due to a phosphor that converts short wave to long wave, to make the tube more efficient. Don't look too long, it promotes cataract development. Rock hound long wave UV lights do not usually have the extra fluorescence, just using the 365nm line through a filter. The more recently-developed UV LED flashlights use a wavelength of 375nm, though this is likely to change as technology continues.
Short wave UV, for rock hounding purposes, is 254nm, a much more energetic light. It can also damage your eyes a lot faster. Glass blocks it, so the special filters used on such light sources use quartz with a filter that blocks visible and long wave UV. Short wave UV makes some substances fluoresce that long wave will not affect, and will also make most (but not all) long-wave-fluorescent substances glow. It sure did the trick for the security features in the check.
After I took the photo above, I just had to check some "security paper" that we all carry: currency. sure enough, as you can see, the 5 and the 20 have certain fluorescent features, while the 1 is basically unresponsive. Take note of the green stripe at the left end of the 20. That and the general blue appearance of the 5 (plus some details near Lincoln's head) are readily visible with a UV LED light, and all the banks and many merchants have them. I didn't have a 10 at the time, but you can be sure the 10, 50 and 100 have similar features. Such features make the bills a lot harder to counterfeit.
I got a check in the mail yesterday, one of those rather official looking ones. On the back, in barely-visible blue ink, where you are supposed to endorse it, it states that security features include a diamond pattern visible when viewed at a low angle, and "invisible fibers". I tried looking at a low angle, and I could indeed just barely see some letters in a diamond pattern. The text also warns not to accept a check that lacks these features. I reckoned that the bank needs to have a way to see the "invisible fibers", so they must be fluorescent, visible by ultraviolet illumination.
A note about UV wavelengths. Until recently, all UV sources were mercury vapor tubes with filters. An ordinary "black light" tube such as those used in rock concerts is long wave UV, at a wavelength of 365nm, one of the strong "lines" in the mercury spectrum.
Visible light is officially in the range 400-700nm, though most people can see a little beyond these limits if the source is bright enough. In particular, the purple glow you see when you look at a black light tube is the 365nm line, plus fluorescence in the range 360-380nm due to a phosphor that converts short wave to long wave, to make the tube more efficient. Don't look too long, it promotes cataract development. Rock hound long wave UV lights do not usually have the extra fluorescence, just using the 365nm line through a filter. The more recently-developed UV LED flashlights use a wavelength of 375nm, though this is likely to change as technology continues.
Short wave UV, for rock hounding purposes, is 254nm, a much more energetic light. It can also damage your eyes a lot faster. Glass blocks it, so the special filters used on such light sources use quartz with a filter that blocks visible and long wave UV. Short wave UV makes some substances fluoresce that long wave will not affect, and will also make most (but not all) long-wave-fluorescent substances glow. It sure did the trick for the security features in the check.
Saturday, July 14, 2012
Connections in the sky
kw: observations, nature, insects, birds
We just returned from a walk in a nearby schoolyard. It rained this morning, and the air is humid. When we walk there we sometimes see a few dragonflies zooming over the grass, catching small insects we usually don't see. This time, at one end, we saw dozens of dragonflies canvassing a small area of a couple of hundred square feet. As we made our rounds, we watched them. Then, we saw that there were many small flies, brown and a little larger than fruit flies. They were probably having a mating flight, triggered by the rain, and they were the prey of the dragonflies. At one point, my wife saw a dragonfly snag one of the little flies right in front of her.
On our last go-round, we looked up to see that there were actually a couple of hundred dragonflies filling the air, to a height of thirty or forty feet. In the top reaches of this insect abundance, three or four swifts were zooming back and forth, taking the occasional dragonfly. There we had it, three links of the food chain on display.
We just returned from a walk in a nearby schoolyard. It rained this morning, and the air is humid. When we walk there we sometimes see a few dragonflies zooming over the grass, catching small insects we usually don't see. This time, at one end, we saw dozens of dragonflies canvassing a small area of a couple of hundred square feet. As we made our rounds, we watched them. Then, we saw that there were many small flies, brown and a little larger than fruit flies. They were probably having a mating flight, triggered by the rain, and they were the prey of the dragonflies. At one point, my wife saw a dragonfly snag one of the little flies right in front of her.
On our last go-round, we looked up to see that there were actually a couple of hundred dragonflies filling the air, to a height of thirty or forty feet. In the top reaches of this insect abundance, three or four swifts were zooming back and forth, taking the occasional dragonfly. There we had it, three links of the food chain on display.
Saturday, June 23, 2012
JCP gets it right
kw: observations, apparel
Two and a half years ago I posted about a printed label inside undershirts, that got scratchy with use. For reference, here is the closeup image of the thick, cracked ink in one of my shirts after being worn about 100 times:
The ink shows obvious cracks, and it is thick and rubbery. When it cracks, it curls a little, making lots of sharp edges. As I wrote, I responded by wearing these shirts inside out. They are under a dress shirt anyway, so they don't show.
I did not report at the time, but the shirt is from J.C. Penney. I didn't want to embarrass them. But I am happy to note the name now, because a year or so later, they changed the ink in this brand of shirt. I have been wearing the new ones right side out (label side in), with no irritation.
In the image below, also after about 100 wearings, though the ink is noticeably wearing, it is rubbing off rather than cracking. It is much thinner than the old ink, and I can't feel it on the shirt.
I don't know whether the changed location of manufacture (Canada instead of the UAE) had anything to do with the change in ink formulation. I hope the primary reason was that JCP folks were wearing their own products and noticed the shortcoming.
Regardless how it came about, bravo to J.C. Penney.
Two and a half years ago I posted about a printed label inside undershirts, that got scratchy with use. For reference, here is the closeup image of the thick, cracked ink in one of my shirts after being worn about 100 times:
I did not report at the time, but the shirt is from J.C. Penney. I didn't want to embarrass them. But I am happy to note the name now, because a year or so later, they changed the ink in this brand of shirt. I have been wearing the new ones right side out (label side in), with no irritation.
In the image below, also after about 100 wearings, though the ink is noticeably wearing, it is rubbing off rather than cracking. It is much thinner than the old ink, and I can't feel it on the shirt.
Regardless how it came about, bravo to J.C. Penney.
Friday, April 27, 2012
A head covered with foam
kw: observations, products, analysis
I am sure you've seen the ads for shampoo, where someone squeezes out an ounce or two of shampoo and lathers up. You see lather flying everywhere. I use one of those advertised shampoos, and I use a drop about the size of a nickel. I began to wonder, just how much does it take to clean my hair?
For most of us, we're really trying to remove oils that our scalps produce, and the amount is really quite small, even for someone with "oily hair". The surfactants in shampoo bind to an amount of oil roughly equal to their own volume. I haven't found any record of some number of milligrams or micrograms of oil that is "normal", so we'll have to make a reasonable estimate.
I have found by observation that if I get my hair very clean, it is pretty flyaway (even if it is no more than two inches long). Within a few hours, it gets more manageable when I brush or comb it, from the first coating of oil. So I estimate that enough oil is produced in about two hours to form a monolayer on all the hair, and production probably continues at this rate all day. By day's end, the hair is not noticeably oily, because a dozen monolayers is still not much oil. Let's calculate how much.
When I had a full head of hair, I kept it about as long as I do now, some 5 cm (2 inches). My hair was brown (getting gray these days), so the number of hair strands was about 50,000. That comes to 250,000 cm or 2,500 m of hair (8,200 ft). Brown hair averages about 60 µm in diameter, so its circumference is about 190 µm, or 0.00019 m. Multiply by 2,500 to get 0.475 m². These are rough calculations, so we'll round it to half a square meter. Just by the way, only about half my scalp has hair now, but the bald portion gets oily, so oil production hasn't slackened off.
To get the volume of one monolayer, now we just need the thickness. Skin oils are hydrocarbon based, so they'll have a sausage shape, with a diameter in the range of half a nanometer, or about 5Ã… (5 angstroms). 0.5m²×0.5nm = 2.5E-10 cubic meters, or 0.00025 cc, or 0.25 cubic mm. Twelve such volumes amount to 3 cubic mm.
So, the amount of oil you need to remove, if you wish to remove it all, is about 3 cubic mm. That is a dot the size of a pin head. Can we really get away with using a similar amount of shampoo? Would it really work? I have yet to make the experiment. My nickel-sized dollop of shampoo is about half a cc, or 500 cubic mm. I'll try smaller and smaller amounts to see how much does an effective job. I suspect there is a lot more at work here than just oil removal.
I am sure you've seen the ads for shampoo, where someone squeezes out an ounce or two of shampoo and lathers up. You see lather flying everywhere. I use one of those advertised shampoos, and I use a drop about the size of a nickel. I began to wonder, just how much does it take to clean my hair?
For most of us, we're really trying to remove oils that our scalps produce, and the amount is really quite small, even for someone with "oily hair". The surfactants in shampoo bind to an amount of oil roughly equal to their own volume. I haven't found any record of some number of milligrams or micrograms of oil that is "normal", so we'll have to make a reasonable estimate.
I have found by observation that if I get my hair very clean, it is pretty flyaway (even if it is no more than two inches long). Within a few hours, it gets more manageable when I brush or comb it, from the first coating of oil. So I estimate that enough oil is produced in about two hours to form a monolayer on all the hair, and production probably continues at this rate all day. By day's end, the hair is not noticeably oily, because a dozen monolayers is still not much oil. Let's calculate how much.
When I had a full head of hair, I kept it about as long as I do now, some 5 cm (2 inches). My hair was brown (getting gray these days), so the number of hair strands was about 50,000. That comes to 250,000 cm or 2,500 m of hair (8,200 ft). Brown hair averages about 60 µm in diameter, so its circumference is about 190 µm, or 0.00019 m. Multiply by 2,500 to get 0.475 m². These are rough calculations, so we'll round it to half a square meter. Just by the way, only about half my scalp has hair now, but the bald portion gets oily, so oil production hasn't slackened off.
To get the volume of one monolayer, now we just need the thickness. Skin oils are hydrocarbon based, so they'll have a sausage shape, with a diameter in the range of half a nanometer, or about 5Ã… (5 angstroms). 0.5m²×0.5nm = 2.5E-10 cubic meters, or 0.00025 cc, or 0.25 cubic mm. Twelve such volumes amount to 3 cubic mm.
So, the amount of oil you need to remove, if you wish to remove it all, is about 3 cubic mm. That is a dot the size of a pin head. Can we really get away with using a similar amount of shampoo? Would it really work? I have yet to make the experiment. My nickel-sized dollop of shampoo is about half a cc, or 500 cubic mm. I'll try smaller and smaller amounts to see how much does an effective job. I suspect there is a lot more at work here than just oil removal.
Tuesday, April 24, 2012
The zipper is just the beginning
kw: observations, history
Today's Google Doodle marks the 132d birthday of the inventor of the zipper, Gideon Sundback. Prior to about a century ago, which is also prior to the use of elastic in waistbands, you had to undo a couple of buttons to get trousers off, which could be a problem if you were in too big a hurry!
But there is more to the day than sartorial developments. The Internet is a wonderful library, and when I get a wild hair about something, its resources astound me. In particular, there are dozens of "this day in history" sites. The best that I've so far found is historyorb.com. Some tidbits from its archive:
But there is more to the day than sartorial developments. The Internet is a wonderful library, and when I get a wild hair about something, its resources astound me. In particular, there are dozens of "this day in history" sites. The best that I've so far found is historyorb.com. Some tidbits from its archive:
- 2005 – Cardinal Joseph Ratzinger becomes Pope Benedict XVI.
- 1996 – Highest scoring baseball game in 17 years: Twins 24, Tigers 11.
- 1990 – West and East Germany agree to merge their currency and economies (to take place on July 1).
- 1981 – Introduction of the IBM PC. Prior to this you had to build one from a kit.
- 1969 – Paul McCartney says there is no truth to rumors that he is dead (Mark Twain said it better 72 years earlier: "Rumors of my death are an exaggeration").
- 1953 – Queen Elizabeth II knights Winston Churchill (and about time, too).
- 1928 – A patent issued to Reginald Fessenden for the fathometer, a sonar device that measures depths underwater. This beats lowering a weight on a marked rope, which may or may not hang vertically.
- 1907 – Milton Hershey opens Hersheypark in Hershey, PA. Initially, it was exclusively for employees.
Wednesday, February 15, 2012
Microstructure matters
kw: observations, materials science
While preparing a talk on the semiprecious varieties of chalcedony, I read in a few articles about the way that these materials were used as tools, primarily in precolonial times. A significant dichotomy stood out: "hitting" tools such as hammers and clubs tend to be made of chert or light colored flint, and cutting tools such as arrow and spear points tend to be made of dark colored flint, or agate or jasper. These depend on material availability, but good material was often traded and transported long distances.
Cryptocrystalline quartz has a range of microstructures, from blocky to fibrous, that affect how the material can be used. These materials are called cryptocrystalline because the crystals cannot be seen under an optical microscope; these are nanomaterials. Seen with an electron microscope, chert and yellow flint have blocky structure, like sand grains compressed to eliminate the porosity, but the grains are very small, smaller than the wavelength of light. Agate, jasper and black or gray flint have a fibrous texture, as though felt had been petrified, again, with the fibrous nanocrystals smaller than a wavelength of light. That is why the broken surface of any of these materials looks very smooth, like broken glass. Yet they are crystalline on a very small scale.
The fibrous cryptocrystalline materials take a sharper edge and hold it better under wear. They are thus valued for cutting tools. Arrow points from the American southwest, for example, are usually agate or petrified wood, even where chert is the more abundant material. And grinding pestles and hammer stones are usually made of chunks of chert. It helps that chert often comes in larger pieces. It does take hammering well, while agate, for example, splinters more easily. But those shards are sharp!
As a lapidary hobbyist, I find jasper, including petrified wood, which is usually jasper, a favorite material for beautiful cabochons. But jasper is particularly tough on grinding wheels. Wheels of silicon carbide grit wear quickly, and diamond-charged wheels lose their diamonds faster—they get plucked out of the matrix—than with any other quartzose material. It comes with the territory. Chert can be beautiful also, but this is rather rare. Most chert is gray or off-white and dull. It takes a good polish, of course, and it is not quite as hard on the equipment. But the fibrous materials are nearly always prettier. Love 'em!
While preparing a talk on the semiprecious varieties of chalcedony, I read in a few articles about the way that these materials were used as tools, primarily in precolonial times. A significant dichotomy stood out: "hitting" tools such as hammers and clubs tend to be made of chert or light colored flint, and cutting tools such as arrow and spear points tend to be made of dark colored flint, or agate or jasper. These depend on material availability, but good material was often traded and transported long distances.
Cryptocrystalline quartz has a range of microstructures, from blocky to fibrous, that affect how the material can be used. These materials are called cryptocrystalline because the crystals cannot be seen under an optical microscope; these are nanomaterials. Seen with an electron microscope, chert and yellow flint have blocky structure, like sand grains compressed to eliminate the porosity, but the grains are very small, smaller than the wavelength of light. Agate, jasper and black or gray flint have a fibrous texture, as though felt had been petrified, again, with the fibrous nanocrystals smaller than a wavelength of light. That is why the broken surface of any of these materials looks very smooth, like broken glass. Yet they are crystalline on a very small scale.
The fibrous cryptocrystalline materials take a sharper edge and hold it better under wear. They are thus valued for cutting tools. Arrow points from the American southwest, for example, are usually agate or petrified wood, even where chert is the more abundant material. And grinding pestles and hammer stones are usually made of chunks of chert. It helps that chert often comes in larger pieces. It does take hammering well, while agate, for example, splinters more easily. But those shards are sharp!
As a lapidary hobbyist, I find jasper, including petrified wood, which is usually jasper, a favorite material for beautiful cabochons. But jasper is particularly tough on grinding wheels. Wheels of silicon carbide grit wear quickly, and diamond-charged wheels lose their diamonds faster—they get plucked out of the matrix—than with any other quartzose material. It comes with the territory. Chert can be beautiful also, but this is rather rare. Most chert is gray or off-white and dull. It takes a good polish, of course, and it is not quite as hard on the equipment. But the fibrous materials are nearly always prettier. Love 'em!
Friday, February 03, 2012
Breakfast blah
kw: observations, food, dry cereals
My wife is a sucker for a bargain. Thus, we often get some new food to try because it has been introduced at a low, low price. This time it was a new breakfast cereal.
I grew up eating Cheerios® (from General Mills). It is hard to overeat with because a "serving" of 3/4 cup has only 100 calories and weighs one ounce (28g). It has only a gram of sugar and three of protein, but 16g of digestible starch, so about 70% of the calories are carbs. I used to eat five ounces almost every morning. I once calculated that I'd eaten one ton of Cheerios® in about fifty years. Nowadays I eat 2-3 ounces when I have it at all.
These days, having but half a colon, I find it better to eat denser foods. My favorites are the series of Post Selects; the one in front of me at the moment is their Great Grains Crunchy Pecans. A 3/4 cup "serving" weighs 51g (1.8 oz) and has 210 calories. So I eat a smaller volume by comparison. It has a lot more sugar, 8g, and 24g of starch, so the carbs make up 60% of the calories (there is 10% more from oils).
Now we come to the bargain of the week. A new brand called Bear Naked®, and their Nut Cluster Crunch, dubbed a "100% natural energy cereal". It is nearly as dense as the Post cereal (49g or 1.7 oz per 3/4 cup), but with fewer calories: 180. It has half the fat of Cheerios®, but 11g of sugar and total carb calories pushing 80%. There are only 4g of protein, so % protein calories are the least for this cereal of the three. Here is the kicker. It tastes like sweetened cardboard, and doesn't soften in milk for a long, long time. It is extremely crunchy and actually makes my gums sore. My wife gets to eat the rest of it.
I took a look at the ingredients lists. The item of interest this morning is sugar. As I said, Cheerios® has the least, 1g per serving (though I eat twice as many servings to get the same calories, so call it 2g). In the ingredient list, the third ingredient is, simply, sugar. To me that means either beet sugar or cane sugar. Both are sucrose. In the Post cereal, the fifth ingredient is brown sugar, and the seventh is sugar. Sucrose again, with a little molasses included. Sugars total 8g per serving. Now for the Bear Naked® stuff. Sugar totals 11g, and the third ingredient is "evaporated cane juice crystals", a fancy-schmancy way of saying sucrose. In their list of things the cereal doesn't have, it says, "NO High Fructose Corn Syrup". Well, the other two cereals don't have any, either. But its level of sucrose is by far the highest of the three. Really sweet cardboard. I'll stick to the Post cereal, which is at least enjoyable to eat.
Tomorrow I'm having eggs and toast.
My wife is a sucker for a bargain. Thus, we often get some new food to try because it has been introduced at a low, low price. This time it was a new breakfast cereal.
I grew up eating Cheerios® (from General Mills). It is hard to overeat with because a "serving" of 3/4 cup has only 100 calories and weighs one ounce (28g). It has only a gram of sugar and three of protein, but 16g of digestible starch, so about 70% of the calories are carbs. I used to eat five ounces almost every morning. I once calculated that I'd eaten one ton of Cheerios® in about fifty years. Nowadays I eat 2-3 ounces when I have it at all.
These days, having but half a colon, I find it better to eat denser foods. My favorites are the series of Post Selects; the one in front of me at the moment is their Great Grains Crunchy Pecans. A 3/4 cup "serving" weighs 51g (1.8 oz) and has 210 calories. So I eat a smaller volume by comparison. It has a lot more sugar, 8g, and 24g of starch, so the carbs make up 60% of the calories (there is 10% more from oils).
Now we come to the bargain of the week. A new brand called Bear Naked®, and their Nut Cluster Crunch, dubbed a "100% natural energy cereal". It is nearly as dense as the Post cereal (49g or 1.7 oz per 3/4 cup), but with fewer calories: 180. It has half the fat of Cheerios®, but 11g of sugar and total carb calories pushing 80%. There are only 4g of protein, so % protein calories are the least for this cereal of the three. Here is the kicker. It tastes like sweetened cardboard, and doesn't soften in milk for a long, long time. It is extremely crunchy and actually makes my gums sore. My wife gets to eat the rest of it.
I took a look at the ingredients lists. The item of interest this morning is sugar. As I said, Cheerios® has the least, 1g per serving (though I eat twice as many servings to get the same calories, so call it 2g). In the ingredient list, the third ingredient is, simply, sugar. To me that means either beet sugar or cane sugar. Both are sucrose. In the Post cereal, the fifth ingredient is brown sugar, and the seventh is sugar. Sucrose again, with a little molasses included. Sugars total 8g per serving. Now for the Bear Naked® stuff. Sugar totals 11g, and the third ingredient is "evaporated cane juice crystals", a fancy-schmancy way of saying sucrose. In their list of things the cereal doesn't have, it says, "NO High Fructose Corn Syrup". Well, the other two cereals don't have any, either. But its level of sucrose is by far the highest of the three. Really sweet cardboard. I'll stick to the Post cereal, which is at least enjoyable to eat.
Tomorrow I'm having eggs and toast.
Monday, January 30, 2012
Let's do biofuels right
kw: observations, biofuels, alternative energy
If you can't read the text in the image, click for a larger version.
This illustration from the November, 2011 issue of Discover deserves a wider audience. It is part of an article showing that it makes great sense to develop biofuel production using algae rather than "large plants" such as corn.
At present, algae can produce 5,000 gallons of biofuel per acre, ten times as much as making ethanol from corn. And we should not be turning food into gasoline anyway! There is little doubt that in the next decade or so the efficiency of algae can be improved, and also that effective methods for large-scale cultivation of the best algal species will be developed.
If you can't read the text in the image, click for a larger version.
This illustration from the November, 2011 issue of Discover deserves a wider audience. It is part of an article showing that it makes great sense to develop biofuel production using algae rather than "large plants" such as corn.At present, algae can produce 5,000 gallons of biofuel per acre, ten times as much as making ethanol from corn. And we should not be turning food into gasoline anyway! There is little doubt that in the next decade or so the efficiency of algae can be improved, and also that effective methods for large-scale cultivation of the best algal species will be developed.
Tuesday, January 24, 2012
Cyber construction
kw: observations, computers, computer security
I've been reading a book about computer hacking, the criminal kind. I find it remarkable just how easy it is. Most of the exploits we've read about have, as their underlying secret, a bit of social engineering. Someone got talked into revealing a password. In any operating system, there are a great many vulnerabilities, but it is typically easier to deceive someone to get access. Our human monitors need our support, because they are both the strongest and the weakest link.
There are problems in general with writing computer software. Computer code is remarkably fragile. A programmer (or programming team) has to think of literally everything that the program may be faced with, and write specific code to respond appropriately. A saying has been going around for years: "If we built houses the way we write computer programs, the first woodpecker that came along would destroy civilization."
I realized why this is so: the materials of construction do not have innate properties that help a program builder achieve his or her objective. If you build a house using stone or brick, the characteristics of the materials automatically assure a basically secure structure. You don't have to worry about (most) people blasting their way in through the wall, you just have to worry about making the doors and windows secure. Think of the three little pigs. The only weak point in the brick house was the chimney, and it was small enough to be defensible.
People have been learning how to build with stone, brick, wood and other materials for thousands of years. It was largely a matter of learning which material has what properties. Computer code has no intrinsic properties that can help you. We have been building software for only about seventy years (except for Ada Lovelace, who wrote software in the 1840s). We have no "stones", so we have to invent them. Software libraries provide building blocks that make programming easier, but there is still a problem. Most of those "building blocks" are still made of "jello". We haven't truly thought of everything yet.
This is because computer code is inherently bosonic, rather than fermionic. A digression into particle physics is needed:
In cyberspace, everything is bosonic unless you specifically write fermionic properties for it. An environment such as Second Life has to be very carefully written, with a good "Physics package" to ensure that you don't walk through a wall. Otherwise, walking through walls is the norm. Buildings would not need doors. Our best security software is an attempt to produce a solid door. Sadly, even the best "firewall" software is a bit softer than the average piece of Balsa wood. If you can't prevent a break-in, you at least have to make the firewall "noisy" so it lets you know when it was broken through.
At my company, a double-layered firewall scheme is used, with plenty of very "noisy" alarms to log entry attempts (or entries), but the key to keeping our environment secure is a large contingent of people who spend all day, every day monitoring the noisemakers and snooping on the incoming traffic. Intrusions still occur, but it's a crack team; not much gets by them, and never for very long.
Thus, people are still the key to good security. Imagine if the front door to your house was made of rice paper (like the internal walls of Japanese houses). You'd need a hired team of bodyguards to keep strangers out. People are fermionic; things bounce off and stuff can't pass through unnoticed.
Until our software libraries include truly bullet-proof code, we'll continue to need human monitoring of everything. That's why you need to have strong passwords (ten or more characters, MiXed CasE and with numb3r5, at the very least), but you also need to monitor your accounts and keep good relations with the folks at the other end who are tasked to also monitor things. A skilled social engineer may get past a company monitor, but if those monitors know you are watching, they are less likely to give in to the blandishments of a fast-talking impersonator.
Jesus said, "When a strong man, fully armed, guards his own house, his possessions are safe, But when someone stronger attacks and overpowers him, he takes away the armor in which the man trusted and divides up his plunder." A hint: hackers are clever, but not strong. Guard your own stuff.
I've been reading a book about computer hacking, the criminal kind. I find it remarkable just how easy it is. Most of the exploits we've read about have, as their underlying secret, a bit of social engineering. Someone got talked into revealing a password. In any operating system, there are a great many vulnerabilities, but it is typically easier to deceive someone to get access. Our human monitors need our support, because they are both the strongest and the weakest link.
There are problems in general with writing computer software. Computer code is remarkably fragile. A programmer (or programming team) has to think of literally everything that the program may be faced with, and write specific code to respond appropriately. A saying has been going around for years: "If we built houses the way we write computer programs, the first woodpecker that came along would destroy civilization."
I realized why this is so: the materials of construction do not have innate properties that help a program builder achieve his or her objective. If you build a house using stone or brick, the characteristics of the materials automatically assure a basically secure structure. You don't have to worry about (most) people blasting their way in through the wall, you just have to worry about making the doors and windows secure. Think of the three little pigs. The only weak point in the brick house was the chimney, and it was small enough to be defensible.
People have been learning how to build with stone, brick, wood and other materials for thousands of years. It was largely a matter of learning which material has what properties. Computer code has no intrinsic properties that can help you. We have been building software for only about seventy years (except for Ada Lovelace, who wrote software in the 1840s). We have no "stones", so we have to invent them. Software libraries provide building blocks that make programming easier, but there is still a problem. Most of those "building blocks" are still made of "jello". We haven't truly thought of everything yet.
This is because computer code is inherently bosonic, rather than fermionic. A digression into particle physics is needed:
- Bosons obey Bose-Einstein physics and, in particular, can pass through one another; many can occupy the same space simultaneously.
- Fermions obey Fermi-Dirac physics and, in particular, cannot pass through one another, but bounce off one another; two fermions cannot occupy the same location.
In cyberspace, everything is bosonic unless you specifically write fermionic properties for it. An environment such as Second Life has to be very carefully written, with a good "Physics package" to ensure that you don't walk through a wall. Otherwise, walking through walls is the norm. Buildings would not need doors. Our best security software is an attempt to produce a solid door. Sadly, even the best "firewall" software is a bit softer than the average piece of Balsa wood. If you can't prevent a break-in, you at least have to make the firewall "noisy" so it lets you know when it was broken through.
At my company, a double-layered firewall scheme is used, with plenty of very "noisy" alarms to log entry attempts (or entries), but the key to keeping our environment secure is a large contingent of people who spend all day, every day monitoring the noisemakers and snooping on the incoming traffic. Intrusions still occur, but it's a crack team; not much gets by them, and never for very long.
Thus, people are still the key to good security. Imagine if the front door to your house was made of rice paper (like the internal walls of Japanese houses). You'd need a hired team of bodyguards to keep strangers out. People are fermionic; things bounce off and stuff can't pass through unnoticed.
Until our software libraries include truly bullet-proof code, we'll continue to need human monitoring of everything. That's why you need to have strong passwords (ten or more characters, MiXed CasE and with numb3r5, at the very least), but you also need to monitor your accounts and keep good relations with the folks at the other end who are tasked to also monitor things. A skilled social engineer may get past a company monitor, but if those monitors know you are watching, they are less likely to give in to the blandishments of a fast-talking impersonator.
Jesus said, "When a strong man, fully armed, guards his own house, his possessions are safe, But when someone stronger attacks and overpowers him, he takes away the armor in which the man trusted and divides up his plunder." A hint: hackers are clever, but not strong. Guard your own stuff.
Sunday, January 08, 2012
Countdown to New Hampshire
kw: observations, politics, debates
I watched the televised debate from New Hampshire last evening, among the Republican candidates. There are now six contenders, Michelle Bachmann having bowed out of the race: John Huntsman, Ron Paul, Mitt Romney, Rick Santorum, Newt Gingrich and Rick Perry. Although Romney, Santorum and Paul are the "front runners", in my view nobody is really out of the running yet.
I would not say there was a clear winner last evening. This was much closer to a real debate than the prior ones, with plenty of back-and-forth among men who had both good and bad things to say about one another. I would say, though, that these candidates are primarily laying the groundwork for most of them (perhaps all) to support whomever is nominated. At least three of them stated that any one of the six would do a better job as President than Barack Obama has been doing.
It is still early days. My own State's primary is not until April 24, by which time 34 States and Territories will have held their primaries or caucuses. Even at that point, I suspect there will be some fluidity and uncertainty about the eventual nominee.
Some have said or written that it might be best to replace this six-month mess with a single primary election date, to be shortly followed by the nominating conventions. I disagree. The present process may be a grueling multiple marathon, but it gives voters a much greater opportunity to get to know the candidates, most of whom visit nearly every State. Our remarkable democratic process probably engages more people than any other known. A single-day primary would force much greater reliance on media advertising, a detriment. There is too much already.
I initially favored Ms Bachmann, but now that she is out, I am still confident that the Republicans will nominate someone who can beat the incumbent, because I am pretty sure any of the remaining six can make a better case for becoming our President, than Mr. Obama can for remaining in his failed Presidency.
I watched the televised debate from New Hampshire last evening, among the Republican candidates. There are now six contenders, Michelle Bachmann having bowed out of the race: John Huntsman, Ron Paul, Mitt Romney, Rick Santorum, Newt Gingrich and Rick Perry. Although Romney, Santorum and Paul are the "front runners", in my view nobody is really out of the running yet.
I would not say there was a clear winner last evening. This was much closer to a real debate than the prior ones, with plenty of back-and-forth among men who had both good and bad things to say about one another. I would say, though, that these candidates are primarily laying the groundwork for most of them (perhaps all) to support whomever is nominated. At least three of them stated that any one of the six would do a better job as President than Barack Obama has been doing.
It is still early days. My own State's primary is not until April 24, by which time 34 States and Territories will have held their primaries or caucuses. Even at that point, I suspect there will be some fluidity and uncertainty about the eventual nominee.
Some have said or written that it might be best to replace this six-month mess with a single primary election date, to be shortly followed by the nominating conventions. I disagree. The present process may be a grueling multiple marathon, but it gives voters a much greater opportunity to get to know the candidates, most of whom visit nearly every State. Our remarkable democratic process probably engages more people than any other known. A single-day primary would force much greater reliance on media advertising, a detriment. There is too much already.
I initially favored Ms Bachmann, but now that she is out, I am still confident that the Republicans will nominate someone who can beat the incumbent, because I am pretty sure any of the remaining six can make a better case for becoming our President, than Mr. Obama can for remaining in his failed Presidency.
Wednesday, January 04, 2012
Chill is like vegetables
kw: observations, weather, temperature
I don't like it, but it is better to have it. Cold weather. As I've gotten older, I have found I have less tolerance for the cold. But I am glad to live somewhere that has a real winter, nearly every year. Over all, it is healthier.
Firstly, it stimulates me and my immune system. I find that I am more susceptible to colds in warm weather. Now that I am in my mid-sixties, I've probably had most of the cold viruses out there, both rhinovirus and adenovirus varieties, so I am immune to them. Yet I still catch a new cold every few years, and it seems to occur in the Spring or Fall.
Secondly, it eliminates pests. The worst years for mosquitoes are after mild winters. The overwintering adults can only hide under the bark or in leaf litter, so a deep enough chill will kill more of them. Any overwintering larvae (of certain varieties only) need pretty deep water to hide in, and if it freezes over wholly, they cannot breathe. The privet rust mites that plague my hedge plants hide under bark or leaf litter also. It can take a week of below 20°F weather to kill them. But I'll still spray with oil in May even if we get a hard few weeks.
Finally, the best fruit trees, apples, pears and cherries, bear better fruit after a long, hard winter, as long as the roots in the ground don't freeze. A deep-rooted apple tree can even do well after a North Dakota winter. The trick is to keep it alive for ten years until the roots get at least six feet deep! That takes a heavy layer of mulch, renewed every Spring and Fall. At this latitude, however, hardly any mulch is needed. We had a cold, snowy winter a year ago, and this year I had a very good harvest of excellent apples.
As much as I may grumble about cold weather, it is like having your vegetables, or getting exercise—better for me and better for my yard and garden.
I don't like it, but it is better to have it. Cold weather. As I've gotten older, I have found I have less tolerance for the cold. But I am glad to live somewhere that has a real winter, nearly every year. Over all, it is healthier.
Firstly, it stimulates me and my immune system. I find that I am more susceptible to colds in warm weather. Now that I am in my mid-sixties, I've probably had most of the cold viruses out there, both rhinovirus and adenovirus varieties, so I am immune to them. Yet I still catch a new cold every few years, and it seems to occur in the Spring or Fall.
Secondly, it eliminates pests. The worst years for mosquitoes are after mild winters. The overwintering adults can only hide under the bark or in leaf litter, so a deep enough chill will kill more of them. Any overwintering larvae (of certain varieties only) need pretty deep water to hide in, and if it freezes over wholly, they cannot breathe. The privet rust mites that plague my hedge plants hide under bark or leaf litter also. It can take a week of below 20°F weather to kill them. But I'll still spray with oil in May even if we get a hard few weeks.
Finally, the best fruit trees, apples, pears and cherries, bear better fruit after a long, hard winter, as long as the roots in the ground don't freeze. A deep-rooted apple tree can even do well after a North Dakota winter. The trick is to keep it alive for ten years until the roots get at least six feet deep! That takes a heavy layer of mulch, renewed every Spring and Fall. At this latitude, however, hardly any mulch is needed. We had a cold, snowy winter a year ago, and this year I had a very good harvest of excellent apples.
As much as I may grumble about cold weather, it is like having your vegetables, or getting exercise—better for me and better for my yard and garden.
Wednesday, December 14, 2011
Nannyism - piled higher and deeper
kw: regulations, observations
Do y'all remember the OSHA Cowboy? 'Taint nothin' compared to what we'll soon have to do to drive in these parts. The National Transportation Safety Board (NTSB, pronounced "knee jerks") has "recommended" that the Federal and/or State governments make laws banning all use of communications devices while driving. The aim is to reduce "distractions".
Y'know what distracts me when I'm driving? People who don't look before changing lanes or turning; people who cut me off in an effort to get to work three seconds earlier (like they want to work more today???); people who fly by me at 20-30 miles over the speed limit, when I'm going only 10 over; and especially people who are really distracted, visibly so, because they have a book or newspaper open on the steering wheel, or are combing hair or putting on makeup. I actually saw a laptop propped on a steering wheel.
I don't mind laws requiring hands-free communications, such as Bluetooth. I wonder if using your phone on speaker while it is in your shirt pocket counts… that is what I do. I also only make calls when at a stop light or stop sign (he intoned primly).
But if we're going to reduce distractions, we need to consider these also:
Do y'all remember the OSHA Cowboy? 'Taint nothin' compared to what we'll soon have to do to drive in these parts. The National Transportation Safety Board (NTSB, pronounced "knee jerks") has "recommended" that the Federal and/or State governments make laws banning all use of communications devices while driving. The aim is to reduce "distractions".Y'know what distracts me when I'm driving? People who don't look before changing lanes or turning; people who cut me off in an effort to get to work three seconds earlier (like they want to work more today???); people who fly by me at 20-30 miles over the speed limit, when I'm going only 10 over; and especially people who are really distracted, visibly so, because they have a book or newspaper open on the steering wheel, or are combing hair or putting on makeup. I actually saw a laptop propped on a steering wheel.
I don't mind laws requiring hands-free communications, such as Bluetooth. I wonder if using your phone on speaker while it is in your shirt pocket counts… that is what I do. I also only make calls when at a stop light or stop sign (he intoned primly).
But if we're going to reduce distractions, we need to consider these also:
- Radios - particularly tuning the radio while in motion.
- CD Players - particularly reloading five CD's when the stack of five already in there runs out.
- CB Radios - Actually, I find using a CB quite a bit more distracting than using a handheld phone: changing channels on an "Up 5" request, for instance.
- Passengers - will we be safer of carpooling is banned?
Thursday, November 17, 2011
Energy Spectrum
kw: analysis, observations, particle physics
While a number of web sites illustrate the energy spectrum, none covers the entire useful range. This picture shows a chart that I'd have preferred as a table, but this blogging tool does a particularly bad job displaying tables. To see the table more clearly, right click on it and choose "Open Link in New Tab" or "Open Link in New Window".
While this might be called the electromagnetic spectrum, I have specifically included a range of energies very seldom probed by photons, energies higher than a few GeV, which are typically found only in baryons accelerated by synchrotrons and in cosmic rays. At these high energies, the particles are moving close enough to c that the wavelength-energy conversion is a reasonable approximation.
This is an energy spectrum, so the table is based on the energy, in electron-volts (eV) in the first two columns. Column 1 is the lower limit of a decade range shown in scientific notation, and Column 2 (blue) shows more conventional units for each range, from 100 femto-eV (feV) to 1 Zetta-eV (ZeV). The reason I went no further will be explained later on.
The central column, wavelength (λ), ranges downward from tens of thousands of km to the yoctometer (ym) range, and smaller. The ym is the smallest defined length unit, though I suppose I could have expressed these shorter wavelengths in Planck units. The conversion from E to λ is hc, or 1.2398419 eV-μ, which is 1.2398419x10-6 eV-m. Rounding to 1.24 eV-μ introduces only a small error, about 0.01%.
The next column, frequency (f, brown), is proportional to energy, and ranges from a few Hz to many YottaHertz (YHz) and higher. This is the highest frequency we have a defined prefix for. The conversion from λ to f is the speed of light, 299,792,458 m/s. Rounding to 3x108 introduces an error less than 0.1%.
Finally, each range has a descriptive term applied, but we should realize there is quite a bit of overlap between some of the ranges. For example, extreme UV and soft x-rays overlap, and the term used depends on how someone is using them. Now let's take a little tour.
We seldom realize it, but we are constantly bathed in a low level of either 50- or 60-Hz "hum" from fluorescent lights, electric motors and other things energized by "wall current". The last time I was in Japan, I noticed that the power in the Tokyo area was 60 Hz, but the rest of the country was still using 50 Hz power. It made a difference in how my electric shaver sounded. By working backward through the conversions, we find that 50 and 60 Hz have wavelengths of 6,000 and 5,000 km, respectively, and photon energies of 2.067x10-13 and 2.48x10-13 eV. In ranges much below 1 eV, photon energy doesn't mean much, because the photoelectric effect or other particle interactions don't operate.
The highest note on a piano is 4,186 Hz (4.186 kHz), based on standard tuning of A=440 Hz. The electromagnetic wavelength of this note is 71.7 km, but the acoustic wavelength in standard, sea-level air is 81mm.
The high squeal of an old, CRT-type TV set is 14.75 kHz, which young people can hear, but oldsters like me cannot. Its EM wavelength is 20.3 km.
I am a radio ham. The lowest frequency hams can use at present is 1.8 MHz, which has a wavelength of 167 m. The band's upper edge is 2 Mhz, with a wavelength of 150 m. The band is called the 160 meter band. There are a large number of amateur and international broadcast short-wave bands in the HF (high frequency) range. The most popular are near 14 MHz, the ham's "20-meter band" (14.0-14.35 MHz, with wavelengths of 21.4-20.0 m) and the broadcasters' "19-meter band" (15.1-15.9 MHz, and 19.9-19.0 m wavelength).
VHF and UHF designate frequencies from 30-300 and 300-3,000 MHz. This very useful range is filled with broadcast TV, point-to-point radio, cellular phone services, and at 2,450 MHz (2.45 GHz), microwave ovens. The microwave oven wavelength is 122 mm. This is a compromise frequency. Firstly, it was a political compromise, as various regulatory bodies had to determine a frequency range that wouldn't interfere with existing communications and control services. But using this frequency rather than one much higher or lower is also a compromise. Microwave ovens don't heat evenly because the way the waves bounce around inside the cavity creates higher- and lower-power spots. A much lower frequency would heat more evenly, but much less efficiently. A very much higher frequency would also heat more evenly, but the heat would not penetrate very deeply into the food, and penetration was considered more important than evenness of heating. Besides, most modern microwave ovens have turntables; just be sure to put the item being heated a little off center, which helps the waves spread around better.
The range of energies considered "radio+microwave" keeps expanding. The current limit is about 100 GHz, with wavelengths near 0.3 mm. Above this is the T-ray or T-wave realm, from 0.1 to 100 THz. These are just beginning to be used in place of backscattered x-rays for screening airport passengers for weapons. They can allow an operator to see weapons that a metal detector would miss. The trouble is, with their sub-millimeter resolution and ability to pass right through most fabrics, they produce a "naked" image of a person, so at least in America, there are huge privacy fights going on about them. Personally, I figure if an operator, whether male or female, gets a few jollies from seeing a T-wave image of me, that's not my problem, it is his or hers.
Wavelengths shorter than about 0.1mm are called extreme infrared (EIR), and the IR ranges through far IR (FIR, but used rarely) to near IR, which ends at 0.7μ, at the red end of visible light. The remote control that runs your TV uses one of two IR wavelengths, either 0.8μ or 1.2μ, both of which are pretty easy to produce and detect. The shorter wavelength is less common, because many Asian people can see it. The frequency of 0.8μ is 375 THz, and of 1.2μ is 250 THz. Here the photoelectric effect gets going well enough that it is worth reporting the energies: 1.55 and 1.03 eV, respectively.
The wavelength of greatest visibility is usually quoted as 555nm (0.555μ), with a frequency of 540 THz and a photon energy of 2.23 eV. The bluest light usually seen is at 400 nm, although people who have had cataracts removed can see near-UV light as "blue" as 360 nm. These limits have frequencies of 750 and 833 THz, respectively, and photon energies of 3.10 and 3.44 eV.
Light bluer than about 300 nm is absorbed by the atmosphere, but shorter wavelengths in the "vacuum UV" range are very useful for chemical identification. They are also useful for astronomy, so far-UV and extreme-UV telescopes have been placed in orbit. The conventional limit of UV astronomy is 91.2 nm, because shorter wavelengths are strongly absorbed by neutral hydrogen in space. This limit's frequency is 3,290 THz or 3.29 PHz. Above the PetaHertz range we seldom mention frequency, because we are in the realm of particle behavior. This limit has a photon energy of 13.6 eV, which is enough to totally ionize a hydrogen atom.
X-rays are defined as electromagnetic radiation produced by accelerated electrons, further delimited as ionizing, so the softest x-rays are the 92.1 nm radiation that ionizes hydrogen.
From this point, particle energy is the key parameter and secondarily, wavelength. The beginning of the soft x-ray range is conventionally 10 nm, with photon energy of 124 eV. X-rays are not very penetrating at energies below about 1 keV, which has a wavelength of 1.24 nm. Your doctor's or dentist's x-ray machine uses a broad-spectrum source with a peak near 60 keV and a wavelength near 0.02 nm or 20 pm. In older literature, this was called 0.2 Angstroms. The hardest x-rays are about twice this energetic, at 120 keV and 10 pm wavelength.
Gamma radiation originates in the atomic nucleus, or by energetic particle interactions such as electron-positron annihilation. The softest gamma rays are about as energetic as soft x-rays, but the typical gamma ray has an energy of one or more MeV. Gamma rays as energetic as 6 MeV are produced by alpha emitters such as Uranium; such a photon has a wavelength of 0.2 pm or 200 fm (femtometers). Gamma ray photons and other particles with such energies are useful probes of the nucleus, which is also measured in fm.
One useful gamma radiation energy is 511 keV, which equals the rest mass of an electron. When an electron and a positron annihilate each other, they produce two gamma rays with this energy (and a 2 pm wavelength). In particle accelerators, protons and antiprotons are produced in copious amounts. Annihilation radiation for proton-antiproton interaction is a pair of gamma ray photons with an energy of 938 MeV. This near-GeV range is the upper limit of useful gamma ray photon energies. There are no natural processes that produce photons above this range, except scattering of lower-energy photons by cosmic rays.
Cosmic rays are not photons, they are matter particles: mostly protons, a few electrons, and even fewer heavier nuclei. They come in energies throughout the energy range, but particles with less than 9 GeV don't make it through the Earth's magnetic field. Some are guided by the field to Earth's poles, where they stimulate aurorae. More energetic particles reach the atmosphere and scatter off atmospheric atoms to create air showers of less energetic particles. Detecting and summing up an air shower allows us to characterize the original particle, at least by its incoming energy.
The spectrum of cosmic rays is scale-free, smoothly descending in numbers with higher energies, to a cutoff near 6x1019 eV. Above this energy, an energetic proton that has traveled more than a hundred million parsecs will have scattered off many photons of the cosmic background radiation, losing energy even while it produces those rare multi-GeV photons. In spite of this, a few huge air showers have been detected that indicate an ultra-high-energy cosmic ray occasionally makes it through to Earth with an energy between 1 and 3x1020 eV. That last represents a proton with the energy of a well thrown baseball, as much as 50 Joules.
It is not known how the most energetic cosmic rays originate. Perhaps a proton-proton collision can give one a "kick" at the expense of the other, near enough to Earth that CMB scattering doesn't bleed off too much energy. I suspect the limit of my scale, at 1021 eV, will never be detected. The air shower would be larger than the largest detector array we can build on the planet's surface!
Tour over. You may now unbuckle your seat belt and disembark.
While a number of web sites illustrate the energy spectrum, none covers the entire useful range. This picture shows a chart that I'd have preferred as a table, but this blogging tool does a particularly bad job displaying tables. To see the table more clearly, right click on it and choose "Open Link in New Tab" or "Open Link in New Window".
While this might be called the electromagnetic spectrum, I have specifically included a range of energies very seldom probed by photons, energies higher than a few GeV, which are typically found only in baryons accelerated by synchrotrons and in cosmic rays. At these high energies, the particles are moving close enough to c that the wavelength-energy conversion is a reasonable approximation.This is an energy spectrum, so the table is based on the energy, in electron-volts (eV) in the first two columns. Column 1 is the lower limit of a decade range shown in scientific notation, and Column 2 (blue) shows more conventional units for each range, from 100 femto-eV (feV) to 1 Zetta-eV (ZeV). The reason I went no further will be explained later on.
The central column, wavelength (λ), ranges downward from tens of thousands of km to the yoctometer (ym) range, and smaller. The ym is the smallest defined length unit, though I suppose I could have expressed these shorter wavelengths in Planck units. The conversion from E to λ is hc, or 1.2398419 eV-μ, which is 1.2398419x10-6 eV-m. Rounding to 1.24 eV-μ introduces only a small error, about 0.01%.
The next column, frequency (f, brown), is proportional to energy, and ranges from a few Hz to many YottaHertz (YHz) and higher. This is the highest frequency we have a defined prefix for. The conversion from λ to f is the speed of light, 299,792,458 m/s. Rounding to 3x108 introduces an error less than 0.1%.
Finally, each range has a descriptive term applied, but we should realize there is quite a bit of overlap between some of the ranges. For example, extreme UV and soft x-rays overlap, and the term used depends on how someone is using them. Now let's take a little tour.
Acoustic Range
We seldom realize it, but we are constantly bathed in a low level of either 50- or 60-Hz "hum" from fluorescent lights, electric motors and other things energized by "wall current". The last time I was in Japan, I noticed that the power in the Tokyo area was 60 Hz, but the rest of the country was still using 50 Hz power. It made a difference in how my electric shaver sounded. By working backward through the conversions, we find that 50 and 60 Hz have wavelengths of 6,000 and 5,000 km, respectively, and photon energies of 2.067x10-13 and 2.48x10-13 eV. In ranges much below 1 eV, photon energy doesn't mean much, because the photoelectric effect or other particle interactions don't operate.
The highest note on a piano is 4,186 Hz (4.186 kHz), based on standard tuning of A=440 Hz. The electromagnetic wavelength of this note is 71.7 km, but the acoustic wavelength in standard, sea-level air is 81mm.
The high squeal of an old, CRT-type TV set is 14.75 kHz, which young people can hear, but oldsters like me cannot. Its EM wavelength is 20.3 km.
Radio
I am a radio ham. The lowest frequency hams can use at present is 1.8 MHz, which has a wavelength of 167 m. The band's upper edge is 2 Mhz, with a wavelength of 150 m. The band is called the 160 meter band. There are a large number of amateur and international broadcast short-wave bands in the HF (high frequency) range. The most popular are near 14 MHz, the ham's "20-meter band" (14.0-14.35 MHz, with wavelengths of 21.4-20.0 m) and the broadcasters' "19-meter band" (15.1-15.9 MHz, and 19.9-19.0 m wavelength).
VHF and UHF designate frequencies from 30-300 and 300-3,000 MHz. This very useful range is filled with broadcast TV, point-to-point radio, cellular phone services, and at 2,450 MHz (2.45 GHz), microwave ovens. The microwave oven wavelength is 122 mm. This is a compromise frequency. Firstly, it was a political compromise, as various regulatory bodies had to determine a frequency range that wouldn't interfere with existing communications and control services. But using this frequency rather than one much higher or lower is also a compromise. Microwave ovens don't heat evenly because the way the waves bounce around inside the cavity creates higher- and lower-power spots. A much lower frequency would heat more evenly, but much less efficiently. A very much higher frequency would also heat more evenly, but the heat would not penetrate very deeply into the food, and penetration was considered more important than evenness of heating. Besides, most modern microwave ovens have turntables; just be sure to put the item being heated a little off center, which helps the waves spread around better.
The range of energies considered "radio+microwave" keeps expanding. The current limit is about 100 GHz, with wavelengths near 0.3 mm. Above this is the T-ray or T-wave realm, from 0.1 to 100 THz. These are just beginning to be used in place of backscattered x-rays for screening airport passengers for weapons. They can allow an operator to see weapons that a metal detector would miss. The trouble is, with their sub-millimeter resolution and ability to pass right through most fabrics, they produce a "naked" image of a person, so at least in America, there are huge privacy fights going on about them. Personally, I figure if an operator, whether male or female, gets a few jollies from seeing a T-wave image of me, that's not my problem, it is his or hers.
Near-Visible and Visible Ranges
Wavelengths shorter than about 0.1mm are called extreme infrared (EIR), and the IR ranges through far IR (FIR, but used rarely) to near IR, which ends at 0.7μ, at the red end of visible light. The remote control that runs your TV uses one of two IR wavelengths, either 0.8μ or 1.2μ, both of which are pretty easy to produce and detect. The shorter wavelength is less common, because many Asian people can see it. The frequency of 0.8μ is 375 THz, and of 1.2μ is 250 THz. Here the photoelectric effect gets going well enough that it is worth reporting the energies: 1.55 and 1.03 eV, respectively.
The wavelength of greatest visibility is usually quoted as 555nm (0.555μ), with a frequency of 540 THz and a photon energy of 2.23 eV. The bluest light usually seen is at 400 nm, although people who have had cataracts removed can see near-UV light as "blue" as 360 nm. These limits have frequencies of 750 and 833 THz, respectively, and photon energies of 3.10 and 3.44 eV.
Light bluer than about 300 nm is absorbed by the atmosphere, but shorter wavelengths in the "vacuum UV" range are very useful for chemical identification. They are also useful for astronomy, so far-UV and extreme-UV telescopes have been placed in orbit. The conventional limit of UV astronomy is 91.2 nm, because shorter wavelengths are strongly absorbed by neutral hydrogen in space. This limit's frequency is 3,290 THz or 3.29 PHz. Above the PetaHertz range we seldom mention frequency, because we are in the realm of particle behavior. This limit has a photon energy of 13.6 eV, which is enough to totally ionize a hydrogen atom.
X-Rays
X-rays are defined as electromagnetic radiation produced by accelerated electrons, further delimited as ionizing, so the softest x-rays are the 92.1 nm radiation that ionizes hydrogen.
From this point, particle energy is the key parameter and secondarily, wavelength. The beginning of the soft x-ray range is conventionally 10 nm, with photon energy of 124 eV. X-rays are not very penetrating at energies below about 1 keV, which has a wavelength of 1.24 nm. Your doctor's or dentist's x-ray machine uses a broad-spectrum source with a peak near 60 keV and a wavelength near 0.02 nm or 20 pm. In older literature, this was called 0.2 Angstroms. The hardest x-rays are about twice this energetic, at 120 keV and 10 pm wavelength.
Gamma Radiation
Gamma radiation originates in the atomic nucleus, or by energetic particle interactions such as electron-positron annihilation. The softest gamma rays are about as energetic as soft x-rays, but the typical gamma ray has an energy of one or more MeV. Gamma rays as energetic as 6 MeV are produced by alpha emitters such as Uranium; such a photon has a wavelength of 0.2 pm or 200 fm (femtometers). Gamma ray photons and other particles with such energies are useful probes of the nucleus, which is also measured in fm.
One useful gamma radiation energy is 511 keV, which equals the rest mass of an electron. When an electron and a positron annihilate each other, they produce two gamma rays with this energy (and a 2 pm wavelength). In particle accelerators, protons and antiprotons are produced in copious amounts. Annihilation radiation for proton-antiproton interaction is a pair of gamma ray photons with an energy of 938 MeV. This near-GeV range is the upper limit of useful gamma ray photon energies. There are no natural processes that produce photons above this range, except scattering of lower-energy photons by cosmic rays.
Cosmic Rays
Cosmic rays are not photons, they are matter particles: mostly protons, a few electrons, and even fewer heavier nuclei. They come in energies throughout the energy range, but particles with less than 9 GeV don't make it through the Earth's magnetic field. Some are guided by the field to Earth's poles, where they stimulate aurorae. More energetic particles reach the atmosphere and scatter off atmospheric atoms to create air showers of less energetic particles. Detecting and summing up an air shower allows us to characterize the original particle, at least by its incoming energy.
The spectrum of cosmic rays is scale-free, smoothly descending in numbers with higher energies, to a cutoff near 6x1019 eV. Above this energy, an energetic proton that has traveled more than a hundred million parsecs will have scattered off many photons of the cosmic background radiation, losing energy even while it produces those rare multi-GeV photons. In spite of this, a few huge air showers have been detected that indicate an ultra-high-energy cosmic ray occasionally makes it through to Earth with an energy between 1 and 3x1020 eV. That last represents a proton with the energy of a well thrown baseball, as much as 50 Joules.
It is not known how the most energetic cosmic rays originate. Perhaps a proton-proton collision can give one a "kick" at the expense of the other, near enough to Earth that CMB scattering doesn't bleed off too much energy. I suspect the limit of my scale, at 1021 eV, will never be detected. The air shower would be larger than the largest detector array we can build on the planet's surface!
Tour over. You may now unbuckle your seat belt and disembark.
Tuesday, November 15, 2011
Visual sorting
kw: observations, visual skills, hobbies
I managed to collect all the 50 US State quarters that were produced since 1999, plus the US territory quarters that came out afterwards. When I got a duplicate, I gave it to my wife, and she also kept most of the State quarters she encountered. She has them all in a box, at least until this morning.
She decided to put them in Whitman folders, and asked for my collection to use as a model. Now, there are two ways I can think of to accomplish this task. One is to use preprinted folders that have each state and year, plus P and D mint marks, so there are two each. Then you just go through, coin after coin, and find its spot in the array.
She only wanted the backs shown, and doesn't care about mint marks, so she got blank folders. The second way is then to sort them into years, because there were five quarters minted each year. Then my collection could be used as a model to get each year into the right order. She did it a third way, a way I could not have used.
She spread them all out on the table, face down, and just looked at them for a while. Then she looked at my coins, muttered "Delaware", unerringly picked out the Delaware coin from the array and put it in the first spot in her folder. She continued with New Jersey, and so on. When I asked why she didn't sort them by years first, she told me she was just using the picture on the back of each coin. She could see it better than the year.
Somehow, probably subconsciously, she had spent no more than a couple of minutes looking at the spread of nearly 100 quarters on the tabletop, and sorted the pictures on their backs. Her visual memory really amazed me. No wonder she always wins at MasterMind!
I managed to collect all the 50 US State quarters that were produced since 1999, plus the US territory quarters that came out afterwards. When I got a duplicate, I gave it to my wife, and she also kept most of the State quarters she encountered. She has them all in a box, at least until this morning.
She decided to put them in Whitman folders, and asked for my collection to use as a model. Now, there are two ways I can think of to accomplish this task. One is to use preprinted folders that have each state and year, plus P and D mint marks, so there are two each. Then you just go through, coin after coin, and find its spot in the array.
She only wanted the backs shown, and doesn't care about mint marks, so she got blank folders. The second way is then to sort them into years, because there were five quarters minted each year. Then my collection could be used as a model to get each year into the right order. She did it a third way, a way I could not have used.
She spread them all out on the table, face down, and just looked at them for a while. Then she looked at my coins, muttered "Delaware", unerringly picked out the Delaware coin from the array and put it in the first spot in her folder. She continued with New Jersey, and so on. When I asked why she didn't sort them by years first, she told me she was just using the picture on the back of each coin. She could see it better than the year.
Somehow, probably subconsciously, she had spent no more than a couple of minutes looking at the spread of nearly 100 quarters on the tabletop, and sorted the pictures on their backs. Her visual memory really amazed me. No wonder she always wins at MasterMind!
Friday, November 11, 2011
Mister Biv
kw: observations, colors
I am reading a book about the history of Indigo dye, which I'll review in a day or two. Meanwhile, I was thinking about the influence that indigo had on Isaac Newton. While the essential blue dye of the Anglo-Saxons was woad, indigo from India and Africa was becoming better-known. While the two dyes are chemically similar, indigo is longer-lasting, though both run and stain.
Newton enshrined the deep blue of a strong tincture of indigo in his spectrum, leading to the name for the "color man": Roy G. Biv. I suspect if he hadn't had theological reasons to prefer the number seven to the number six, he'd have left indigo off the list.
The other colors are all quite distinct, and seem to have their places in the spectrum. The continuous spectrum image on the left is a rendering intended to appear as much like a natural spectrum as is possible on a monitor screen. The color blocks I placed near it are, in the case of Red, Yellow and Green, pure rgb colors (r, r+g and g), while the color I labeled Indigo is actually the rgb Blue (b).
The "Orange" is r+0.5g, the "Blue" is b+0.5g, and the "Violet" is b+0.5r. It is likely that "Blue" to Newton was even closer to Cyan (b+g), but it is clear he demarcated a range of color very near the spot in the spectrum at which the R cone in the eye has minimum reaction, the purest blues the eye can see, and labeled it Indigo. The purplish look of the violet range is because the R cone has an extra response peak there.
Isaac Newton did pretty well, having as yet no scientific basis for the colorimetry of the normal eye. We can be sure, though, that he had pretty normal (or "ordinary") vision, because had he been color blind or color-anomalous, he'd have been unable to distinguish this many major hues. Now that we know more about color opposition and have more scientific colorimetry available, old Mr. Biv is giving way to RyGcBm, which is pretty hard to render as a name!
I am reading a book about the history of Indigo dye, which I'll review in a day or two. Meanwhile, I was thinking about the influence that indigo had on Isaac Newton. While the essential blue dye of the Anglo-Saxons was woad, indigo from India and Africa was becoming better-known. While the two dyes are chemically similar, indigo is longer-lasting, though both run and stain.Newton enshrined the deep blue of a strong tincture of indigo in his spectrum, leading to the name for the "color man": Roy G. Biv. I suspect if he hadn't had theological reasons to prefer the number seven to the number six, he'd have left indigo off the list.
The other colors are all quite distinct, and seem to have their places in the spectrum. The continuous spectrum image on the left is a rendering intended to appear as much like a natural spectrum as is possible on a monitor screen. The color blocks I placed near it are, in the case of Red, Yellow and Green, pure rgb colors (r, r+g and g), while the color I labeled Indigo is actually the rgb Blue (b).
The "Orange" is r+0.5g, the "Blue" is b+0.5g, and the "Violet" is b+0.5r. It is likely that "Blue" to Newton was even closer to Cyan (b+g), but it is clear he demarcated a range of color very near the spot in the spectrum at which the R cone in the eye has minimum reaction, the purest blues the eye can see, and labeled it Indigo. The purplish look of the violet range is because the R cone has an extra response peak there.
Isaac Newton did pretty well, having as yet no scientific basis for the colorimetry of the normal eye. We can be sure, though, that he had pretty normal (or "ordinary") vision, because had he been color blind or color-anomalous, he'd have been unable to distinguish this many major hues. Now that we know more about color opposition and have more scientific colorimetry available, old Mr. Biv is giving way to RyGcBm, which is pretty hard to render as a name!
Friday, November 04, 2011
Pink morning sky
kw: observations, photographs, sky
This morning I left for work just before sunrise. I stopped long enough to take a few pictures of the sky, pink from horizon to horizon. This first image, a vertical panorama, shows from the East almost to the zenith.
This second image is of the Western sky. Though I took an image above it, the stitching program couldn't get the two to go together.
A great way to start the day. I was satisfied just to stand and watch it for a few minutes before getting in to the car and starting my workday.
This morning I left for work just before sunrise. I stopped long enough to take a few pictures of the sky, pink from horizon to horizon. This first image, a vertical panorama, shows from the East almost to the zenith.
This second image is of the Western sky. Though I took an image above it, the stitching program couldn't get the two to go together.
A great way to start the day. I was satisfied just to stand and watch it for a few minutes before getting in to the car and starting my workday.
Subscribe to:
Posts (Atom)
Posts
