Route 66, here we come!

The other day a group of us curmudgeons were lamenting the fact that today's pimply grocery clerks can't mentally figure out the change, and are left helpless when the power goes out. The old standard argument came up about how electronic calculators have weakened our maths skills.

I realized that a similar type of malady has afflicted me, as I have become overly dependent on a different electronic gizmo - the GPS navigation in my car. What should be a basic skill, finding one's way from place to place, is left to a device that has many more ways to fail than one's memory. Many cars are now coming with this option available, and there are many portable units available to install in older cars. More and more people are probably losing their ability to navigate, and becoming dependent on these little devices.

However, in using this amazing technology, I have also come to realize a wonderful benefit. In suggesting several choices of routes to take, it is letting me explore routes I never would have driven on my own, including some beautiful small back-country roads. That made me think that perhaps this GPS nav technology will begin to revive some of the small towns that the interstate system killed off in the late 1950's. Location near a main highway will not be such a necessity for businesses like hospitality, where being 'away from it all' is in fact a plus. Finding any location, business or otherwise, will become much easier.

There has been a lot of discussion in urban planning circles about whether repeated cul-de-sac patterns are more conducive to 'neighbourliness' than strict grid patterns. The premise is that more complex and confusing street patterns discourage traffic flow (enhancing safety for children), and make it harder for criminals to 'case' houses for burglary. The GPS technology of course defeats the non-connectedness of the streets.

In fact, the rise of this technology may also mean that many short-cuts once known only to the locals will be more used, and that many now-quiet streets might carry more traffic. I also wonder whether this new 'accessibility' that GPS nav gives will affect the very design of our cities and their suburbs. It may well also open up areas to developers that until now had been too out of the way for consideration.

Lost and Found:

The internet, and its associated tools like Google, are now the PTM--public technical means--for the obtention of intelligence.

There are presumably also significant National Technical Means that use the internet. It's like a whole new dimension for intelligence opened up during the nineties. Of course, ELINT predated the internet (or even MILNET, for that matter), but the internet's connectivity, in combination with the tracks users leave, has proved a goldmine for intelligence gathering.

The convergence of personal electronics will bring some interesting developments. Being able to combine telephone, GPS, personal directories, and wireless communications will mean that we will be able to query our PDA to find the whereabouts of someone, and also get a quick brief on an approaching acquaintance. Our PDAs will be able to pre-negotiate any necessary interactions. Just imagine: "Hey Frank, good to see you - it's been 43 months since I saw you last in Kuala Lumpur. Say, you owe me 45,000 yen, don't you? I know you did well on your last Apple stock sale..."

Yes, a bit creepy.

A few days ago I was able to use Google and a directory service to track down a person I had last seen in South America over twenty-five years ago. I was blown away when I got the message that they were in fact the person I was looking for, and it made me think about setting up a list of lost persons. Since one activity we all do (but don't confess to) is Google ourselves, I can only hope for some hits off this method.

If you're not on the list, I either know where you are, can't remember your name, or (horrors) don't want to hear from you.

Here goes (with last known locations):

From Bogotá, mostly from The English School, Bogotá Sports Club, or Camp Catay:

• Justin and Louise Abel (UK)
  
• Judith Bridger FOUND
  
• Robert FOUND and Vivian Capurro (UK/Mexico)
  
• Mariana Cerna (Colombia)
  
• Matthew Coombs (UK)
  
• Susan England (UK)
  
• Josie Fernández (Costa Rica)
  
• Alexandra Getz (Colombia) FOUND
  
• Leslie & John-Paul Gouffray FOUND
  
• Anja Huikeshoven (UK)
  
• Amanda Kohring (USA)
  
• Ricky Leizgold (USA)
  
• Monica Mannheim (Germany)
  
• Anna Marklund (Sweden)
  
• Magda Miller (NZ)
  
• John & Peter FOUND Orrock (UK)
  
• Fiona Paterson (France)
  
• Peter Tom Petersen (Norway)
  
• Jamie Pigg (UK)
  
• George & Patrick Raikes (Colombia)
  
• Humberto Rodríguez (Colombia)
  
• Julie Rushin (RSA)
  
• Daniel Sarmiento (Colombia)
  
• Monica Savdie (Colombia)
  
• André Smith (Colombia)
  
• Bob Stewart (UK)
  
• William Swan (Ireland)
  
• Janice Tester (Colombia)
  
• Derek, David & Nina Tibble (Colombia)
  
• Ray Youngblood (USA)
  
• David Walker (UK)
  
• Jamshid "Jammie" ??
  

From Toronto, mostly UCC:

• Martin Abell (Canada)
  
• François Beaubien (Canada)
  
• Claude Boudriau (Canada)almost found
  
• Andrew Briggs (Canada)
  
• Gifford Cochran (CO, USA))almost found
  
• Lionel Conacher (Canada)
  
• Randy Dalton (Canada)
  
• Kevin Daw (USA) FOUND, but lost the e-mail...
  
• Helena Flygare (Costa Rica) FOUND
  
• Jeff Gascho (Bahamas) FOUND
  
• Pietro Guglielmietti (Italy))almost found
  
• Lawrence Koppe (Canada)
  
• Patrick Kwan (USA)
  
• Boris Lebedinsky FOUND
  
• Roger Leung (Hong Kong)
  
• Stuart Lowe (Canada)
  
• Andrew Posselt (CA, USA) FOUND
  
• Qasra Sadri (Iran)
  
• Matt Sime (Jamaica)
  
• Greg Steers (USA)
  
• Cannon Sum (Hong Kong)
  
• Bob Wilson (Canada)
  
• John-Paul Yuen (Hong Kong)
  

From Pasadena, mostly Caltech:

• Steve Chin (CA, USA)
  
• Jim Labrenz (CA, USA)) FOUND
  
• Moose Mussenden (PR, USA)
  
• Sean Moriarty (CA, USA)
  
• Rich Premont (CA, USA)
  
• Gerald Zeininger (CA, USA) FOUND
  
• Mike Ammon (CA, USA)
  

From Boston, mostly MIT & Harvard's Lincolns Inn:

• Fernando Chamberlain (El Salvador) FOUND
  
• Greg & Chantale Chamitoff (TX, USA)
  
• Dana Desonie (OR, USA)
  
• Pietro Dova FOUND, sort of
  
• Gerd Fritsch (Germany)
  
• Eduardo Horowitz (Venezuela)
  
• Darlene Ketten (MA, USA)
  
• Harri & Sirkku Kytömaa (MA, USA)) FOUND
  
• Alice & Dan Lawton (IL, USA)
  
• Mike Machado FOUND
  
• Linda Meinke (MA, USA)
  
• Jaime & Monica Posada Castillo (MA, USA)
  

From Washington DC:

• Victoria Churchville (DC, USA)
  
• Chantale Damas (Brazil, Kenya) FOUND
  
• Alison Dawn Jones (VA, USA)
  
• John Rogers (DC, USA)
  
• Anne Tenney (Germany)
  
• Erica Wyman (VA, USA)
  

From all over the place:

• Carmen Cadena (ID, USA)
  
• Chris & Laureen Davis (MI, USA)
  
• Karl & Nancy Decker (Igloo & Kayak) (VA, USA)
  
• Guy de Teramond (Costa Rica)
  
• Philip Enros (Canada)
  
• Valeria and Mauro Fuentealba (Chile)
  
• Wally Funk (TX, USA)
  
• Lisa Marie Gonzales (CA, USA)
  
• Rachel Graham (Belize)
  
• Janet & Christer Jansson (Sweden)
  
• Tatiana Leon (Costa Rica)
  
• Aristides Lorlesse (Panama)
  
• Ronnie Lovler (FL, USA)
  
• Mohammed Masry (Jeddah, Saudi Arabia)
  
• Jackie Mayi (DC, USA)
  
• Natasha Netkach (Moscow, Russia/CA, USA)
  
• José Daniel Pabón Caicedo (Colombia)
  
• Igor Rudyaev (Moscow, Russia)
  
• Lorena San Román (Costa Rica)
  
• Jane Ellen Stevens (CA, USA) FOUND
  

How to get hold of me? Use your PTM! There are links on this page that will lead you to valid e-mail addresses for me, but I don't put them out there for all to see. You need to do some work too!

Sosigenes revisited (and refined!):

In school we learn early that February occasionally has 29 days, rather than 28. Leap years are necessary because the Earth hasn't spun an integral number of times in one year. If we ignore leap years, the calendar starts to diverge from the seasons.

In 325 A.D. The Council of Nicaea decreed that Easter should fall on the first Sunday after the first full moon after the vernal equinox. The problem lay in trying to predict what calendar date this would actually fall on, so that the Church could prepare a universal set of timetables for celebrating the correct mass. Very quickly the Church ran into problems when the accumulated errors from non-integral days in a lunar month, non-integral lunar months in a year, and non-integral days in a year all piled up on each other.

The last time we sorted out this problem (because the calendar was different from the seasons by ten days by the 12th century), some very interesting people were involved in the mathematics and structures developed to deal with this dilemma. A good technical read is John Heilbron's The Sun in the Church: Cathedrals as Solar Observatories. (1999, Harvard Univ. Press, 392 pp.)

Well, as you know, the solution was the leap-year. And the non-leap-year leap-years (remember 2000?). And the leap-year non-leap-year leap-years... etc. etc. You get the picture. Successive approximations. A complex problem, with a complex solution.

Well of course the more closely you look at it, the more complicated the whole thing is. The problem is that the Earth's day isn't always constant, either. I talked about Earth's wobbles in a previous post, but the issue here is the length of day, or LOD.

It turns out that there are actually leap-seconds, too. Every couple of years, an extra second is snuck in to your day. Now, it's not as noticeable as that wonderful extra hour of sleep we just got, but it is just as important. The reason is that the Earth's rotation is actually slowing down due to tidal friction (which also means that the Moon is slowly getting farther away, and will eventually be lost). A constant clock would slowly gain on the actual rotation of the Earth at a rate of about 2 minutes every hundred years.

"That's no big deal," you say. And I agree, where personal time is concerned. Humans can't notice changes like that. But computers can. For example, the computers that transfer your mortgage and escrow payments at the very last possible moment, in order to earn all possible interest. "Sorry, your payment was late by 1 second" is not something any bank wants to try and tell you. They know they will get an earful, so a completely standardized time is important. Especially if we want to make e-commerce work.

The surprising thing is that no one has really agreed on how to consistently do the leap-second shimmy thing. There are many brands of time out there -- by which I mean: solar, sidereal, Standard, Greenwich Mean, international atomic, GPS, Universal, and Coordinated Universal. And they all differ. Some by as much as 32 seconds. And not all of them leap at the same time. Not surprisingly, with so many to choose from, there are all kinds of problems built in to many computers because of the initial design choices.

You're damned if you do leap: the UTC leap seconds of 1994 and 1997 crashed the Soviet GLONASS navigation system. ...and you're damned if you don't: at midnight on November 27 2003, Motorola Oncore GPS receivers will skip a day, and then correct themselves within the next second, all because the best guess at the time they were designed was that we would have had another UTC leap second by now.

How to resolve this? By committee, of course! The International Telecommunications Union is studying the problem, and they might decide to throw out the leap second entirely. Just not right now, this second. They want to wait until 2022.

Gates, Jobs, McNealy, etc. etc.

It was good to wake up laughing today -- news that a handheld phone was being released with a Windows operating system made me think that just as we get rid of the telephone solicitation scourge here in the U.S., we will be opening opportunities for viruses to call everybody in our cellphone's directory... argh, and with all the junk numbers I compulsively keep in my phone from all my travels, that would be a very expensive virus.

I'm waiting for an all-in-one integrated wearable CDMA2000 EV-DO/EDGSM/CDPD/WiFi phone, GPS and PDA iPOD. But for now I still have my trusty 1997 Newton, which does just fine thanks - it's fully capable of doing most of the above. It's just such a brick.

Boat wakes mad science:

Asked by Lonnie, a science grad student at Virginia Commonwealth University: When flying I often see the trails of where boats have passed. These are obviously not wakes. They generally appear as a lighter colored path showing where the boat travelled. What causes this anomaly in the water's surface appearance?

They actually are wakes. I know exactly what you mean, because I have wondered about them too ? they aren?t the wave trains we?re used to that water skiers jump over, but much longer features trailing many kilometers behind.

Here are some images of ship wakes taken from the Space Shuttle, which include examples of what you are interested in.

It turns out that wakes are pretty complicated things. In fact, this particular type of feature is not yet fully understood, because most dynamical solutions damp out to a level that should be unobservable this far downstream from the ship. What you are seeing is probably a non-linear interaction between some of the wake features I talk about below.

Being able to see these features requires a special combination of circumstances. First, the state of the sea itself has to be calm enough so that this feature is not swamped out. Second, the lighting angle has to be right. Notice in all the photos in the NASA link above that nearly all the wake features are most visible near the point of maximum reflection of the sun ? since the sea provides a specular surface, the reflection of the sun is ?smeared out? over a wide area, providing brilliant illumination that allows you to see very fine details and differences in the sea state (things like eddies, wakes, squalls, etc.). Third, the ship has to be going the right speed, and passing over the right kind of water for non-linear effects to appear.

A ship?s wake is composed of many different phenomena:

1. The familiar set of spreading waves in a 19.5 degree angle V behind any ship is called the ?Kelvin wake? after Lord Kelvin, who gave the first rigorous description of it. There are actually a set of waves which cross the V too. These waves are what eat up most of a ship?s energy. These wakes are long-lasting, and far reaching. There are some fantastic pictures of Kelvin wakes here.

A lot of research has gone into how to reduce this wake and the energy it drains from a ship ? one result was that you can reduce the transverse waves in the set (and the energy required to produce them) by putting a big bulbous part on the bow of the ship. But unfortunately, only at a particular speed. Here?s an interesting page on hull shapes and how they affect drag on ships.

2. The ?turbulent wake? is all the white foam kicked up by the propeller wash/cavitation and the chaotic eddy shedding at the stern. This wake tends to wash out the Kelvin waves that cross perpendicular to the direction of travel. Here?s a picture of the turbulent wake caused by an aircraft carrier. Since it?s turbulent, it tends to damp out pretty quickly.

3. The ?dead water? wake or ?narrow-V? wake, which looks like the ship flattened out the waves. This wake is also always present, but is very hard to observe, since it?s flat! Turning ships often give a good view of it, and here?s a biggie.This is a big part of what you are seeing, but this wake alone cannot last as long as several kilometers.

4. All of the above are really the surface manifestations of what is really a 3-dimensional process ? all of these wakes have a portion below the surface that is just as complex. One of the large parts of the sub-surface wake is a set of twin vortices that are shed from the stern. They are very hard to see in water, but a parallel type of phenomenon is easily observed in airplane wakes, here.

5. Now we get to the weird stuff. At certain speeds, ships can set up long solitary waves (solitons) that precede the ship. You can think of them as the ?draw-down? before the Kelvin wake comes crashing in. If you want to read some more about these, go get this PDF file.

6. The next complication is the structure of the water itself. As you probably know, very often water is stratified in layers of different temperature, salinity, turbidity, etc. This creates conditions where waves can diffract and reflect internally in these layers making all sorts of complicated effects. These can be classed as ?internal wave wakes.? In some cases, if there is a layer of material (oil, say) on the top surface, this disrupts surface tension forces that cause certain wave/wake phenomena ? these are the ?oil slicks? which are generally flatter than surrounding waters. A detailed analysis of surfactants and radar returns is here.


As you might imagine, all of these things are of great interest to people who want to know where ships are, and how to track them. Not only the military and the coast guard, but also ship traffic management and companies that are tracking their ships? progress (like express mail services that use GPS to track the whereabouts of vans, trains, etc.). Radar is very good at this, since it reflects really well from metal corners, but also very poorly from the exact features you are asking about. In radar images, what you see is a very bright ship followed by a very dark, long streak. To find out more about radar and ship tracking go here and here.

So..... the long streaks of calm water that reflect the sunlight better than the surrounding water are most probably a complicated non-linear interaction of the narrow-V, the vortices, and some internal wakes that depend on the exact structure of the water column.

I hope this helped, Lonnie!