I just returned from Jeff Pulver's "140 Characters" conference in L.A. which was about Twitter. I asked many people if they get Twitter -- not if they understand how it's useful, but why it is such a hot item, and whether it deserves to be, with billion dollar valuations and many talking about it as the most important platform.

Some suggested Twitter is not as big as it appears, with a larger churn than expected and some plateau appearing in new users. Others think it is still shooting for the moon.

Saturday saw the dedication of a new autonomous vehicle research center at Stanford, sponsored by Volkswagen. VW provided the hardware for Stanley and Junior, which came 1st and 2nd in the 2nd and 3rd Darpa Grand Challenges, and Junior was on display at the event, driving through the parking lot and along the Stanford streets, then parking itself to a cheering crowd.

Junior continues to be a testing platform with its nice array of sensors and computers, though the driving it did on Saturday was largely done with the Velodyne LIDAR that spins on top of it, and an internal map of the geometry of the streets at Stanford.

New and interesting was a demonstration of the "Valet Parking" mode of a new test vehicle, for now just called Junior 3. What's interesting about J3 is that it is almost entirely stock. All that is added are two lower-cost LIDAR sensors on the rear fenders. It also has a camera at the rear-view mirror (which is stock in cars with night-assist mode) and a few radar sensors used in the fixed-distance cruise control system. J3 is otherwise a Passat. Well, the trunk is filled with computers, but there is no reason what it does could not be done with a hidden embedded computer.

What it does is valet park itself. This is an earlier than expected implementation of one of the steps I outlined in the roadmap to Robocars as robo-valet parking. J3 relies on the fact the "valet" lot is empty of everything but cars and pillars. Its sensors are not good enough to deal well with random civilians, so this technology would only work in an enclosed lot where only employees enter the lot if needed. To use it, the driver brings the car to an entrance marked by 4 spots on the ground the car can see. Then the driver leaves and the car takes over. In this case, it has a map of the garage in its computer, but it could also download that on arrival in a parking lot. Using the map, and just the odometer, it is able to cruise the lanes of the parking lot, looking for an empty spot, which it sees using the radar. (Big metal cars of course show clearly on the radar.) It then drives into the spot.

I've written a lot about how to do better power connectors for all our devices, and the quest for universal DC and AC power plugs that negotiate the power delivered with a digital protocol.

While I've mostly been interested in some way of standardizing power plugs (at least within a given current range, and possibly even beyond) today I was thinking we might want to go further, and make it possible for almost every connector we use to also deliver or receive power.

Some time ago I proposed the "School of Fish Test" as a sort of turing test for robocars. In addition to being a test for the cars, it is also intended to be a way to demonstrate to the public when the vehicles have reached a certain level of safety. (In the test, a swarm of robocars moves ona track, and a skeptic in a sportscar is unable to hit one no matter what they do, like a diver trying to touch fish when swimming through a school.)

I'm impressed with a great interactive map of the U.S. power grid produced by NPR. It lets you see the location of existing and proposed grid lines, and all power plants, plus the distribution of power generation in each state.

Robocar news:

This press release describes a European research project on various intelligent vehicle technologies which will take place next year. As I outline in the roadmap a number of pre-robocar technologies are making their way into regular cars, so they can be sold as safer and more convenient. This project will actively collect data to learn about and improve the systems.

Just back from a weeklong tour including speaking at Singularity Summit, teaching classes at Cushing Academy and a big Thanksgiving dinner (well, Thanksgiving is actually today but we had it earlier) and drive through fabulous fall colour in Muskoka.

I have several sheetfed scanners. They are great in many ways -- though not nearly as automatic as they could be -- but they are expensive and have their limitations when it comes to real-world documents, which are often not in pristine shape.

A serious proportion of the computer users I know these days have gone multi-monitor. While I strongly recommend the 30" monitor (Dell 3007WFP and cousins or Apple) which I have to everybody, at $1000 it's not the most cost effective way to get a lot of screen real estate. Today 24" 1080p monitors are down to $200, and flat panels don't take so much space, so it makes a lot of sense to have two monitors or more.

Tonight I watched the debut of FlashForward, which is based on the novel of the same name by Rob Sawyer, an SF writer from my hometown whom I have known for many years. However, "based on" is the correct phrase because the TV show features Hollywood's standard inability to write a decent time travel story. Oddly, just last week I watched the fairly old movie "Deja Vu" with Denzel Washington, which is also a time travel story.

Hollywood absolutely loves time travel. It's hard to find a Hollywood F/SF TV show that hasn't fallen to the temptation to have a time travel episode. Battlestar Galactica's producer avowed he would never have time travel, and he didn't, but he did have a god who delivered prophecies of the future which is a very close cousin of that. Time travel stories seem easy, and they are fun. They are often used to explore alternate possibilities for characters, which writers and viewers love to see.

But it's very hard to do it consistently. In fact, it's almost never done consistently, except perhaps in shows devoted to time travel (where it gets more thought) and not often even then. Time travel stories must deal with the question of whether a trip to the past (by people or information) changes the future, how it changes it, who it changes it for, and how "fast" it changes it. I have an article in the works on a taxonomy of time travel fiction, but some rough categories from it are:

• Calvinist: Everything is cast, nothing changes. When you go back into the past it turns out you always did, and it results in the same present you came from.
• Alternate world: Going into the past creates a new reality, and the old reality vanishes (at varying speeds) or becomes a different, co-existing fork. Sometimes only the TT (time traveler) is aware of this, sometimes not even she is.
• Be careful not to change the past: If you change it, you might erase yourself. If you break it, you may get a chance to fix it in some limited amount of time.
• Go ahead and change the past: You won't get erased, but your world might be erased when you return to it.
• Try to change the past and you can't: Some magic force keeps pushing things back the way they are meant to be. You kill Hitler and somebody else rises to do the same thing.

Inherent in several of these is the idea of a second time dimension, in which there is a "before" the past was changed and an "after" the past was changed. In this second time dimension, it takes time (or rather time-2) for the changes to propagate. This is mainly there to give protagonists a chance to undo changes. We see Marty Mcfly slowly fade away until he gets his parents back together, and then instantly he's OK again.

In a time travel story, it is likely we will see cause follow effect, reversing normal causality. However, many writers take this as an excuse to throw all logic out the window. And almost all Hollywood SF inconsistently mixes up the various modes I describe above in one way or another.

Spoilers below for the first episode of FlashForward, and later for Deja Vu.

Update note: The fine folks at io9 asked FlashForward's producers about the flaw I raise but they are not as bothered by it.

It seems that with more and more of the online transactions I engage in -- and sometimes even when I don't buy anything -- I will get a request to participate in a customer satisfaction survey. Not just some of the time in some cases, but with every purchase. I'm also seeing it on web sites -- sometimes just for visiting a web site I will get a request to do a survey, either while reading, or upon clicking on a link away from the site.

I have put up a gallery of panoramas for Burning Man 2009. This year I went with the new Canon 5D Mark II, which has remarkable low-light shooting capabilities. As such, I generated a number of interesting new night panoramas in addition to the giant ones of the day.

In particular, you will want to check out the panorama of the crowd around the burn, as seen from the Esplanade, and the night scene around the Temple, and a twilight shot.

Two events I will be at...

Tonight, at 111 Minna Gallery in San Francisco, we at EFF will be hosting a reading by Randall Monroe, creator of the popular nerd comic "xkcd." There is a regular ticket ($30) and a VIP reception ticket ($100) and just a few are still available. Payments are contributions to the EFF.

Two years ago, I discussed solutions for Burning Man Exodus. The problem: Get 45,000 people off the playa in 2 days, 95% of them taking a single highway south which goes through a small town which has a chokepoint capacity of about 450 cars/hour. Quite often wait times to get onto the road are 4 hours or more, though this year things were smoother (perhaps due to a lower attendance) and the number of people with 4 hour waits was lower.

There is a number that should not be horribly hard to calculate by the actuaries of the health insurance companies. In fact, it's a number that they have surely already calculated. What would alternate health insurance systems cost?

Yes, any system which is going to engage in some long activity which will freeze up the system for more than a few seconds should offer a way to cancel, abort or undo it. You would think designers would know that by now.

I just decided to cancel my AAdvantage credit card for a 1% cashback card with no annual fee. Many people have the frequent flyer cards so let's consider the math on them. They typically come with a high annual fee (around $80) while other cards have no fee and other rewards.

After every RV trip (I'm back from Burning Man) I think of more I want RVs to do. This year, as we have for many years, we built a power distribution system with a master generator rather than having each RV run its own noisy, smelly and inefficient generator. However, this is expensive and a lot of work for a small group, it is cheap and a lot of work for a larger group.

There's been a revolution in small generator design of late thanks to the declining cost of inverters and other power conversion. A modern quality generator feeds the output of its windings to circuits to step up and step down the voltage to produce the required power. The output power is cleaner and more stable, and the generator is spun at different RPMs based on the power load, making it quieter and more efficient. With many models, you can also combine the internal output of two generators to produce a higher power generator.

RVs have come with expensive old-style generators that are quieter than cheap ones, and which produce better power, but today they are moving to inverter generators. With an inverter generator, it's also possible to draw on the RV batteries for power surges (such as starting an AC or microwave) beyond what the generator can do.

I'm interested in the potential for smarter power, so what I would like to see is a way for a group of RVs with new generation power systems to plug together. In this way, they could all make use of the power in the other vehicles, and in most cases only a fraction of the generators would need to be running to provide power to all. (For example, at night, only one generator could power a whole cluster. In the day, with ACs running, several would need to run, but it would be very unlikely to have to run all, or even 75% of them.)

RVs all have a fresh water tank. When you rent one, they will often tell you not to drink that water. That's because the tanks are being filled up in all sorts of random places, out of the control of the rental company, and while it's probably safe, they don't want to promise it, nor disinfect the tank every rental.

I recently got a small "pen" which you put in a cup of water and it shines a UV light for 30 seconds to kill any nasties in the water. While I have not tried to test it on infected water, I presume that it works.

The Worldcon (World Science Fiction Convention) in Montreal was enjoyable. Like all worldcons, which are run by fans rather than professional convention staff, it had its issues, but nothing too drastic. Our worst experience actually came from the Delta hotel, which I'll describe below.

For the past few decades, Worldcons have been held in convention centers. They attract from 4,000 to 7,000 people and are generally felt to not fit in any ordinary hotel outside Las Vegas. (They don't go to Las Vegas both because there is no large fan base there to run it, and the Las Vegas Hotels, unlike those in most towns, have no incentive to offer a cut-rate deal on a summer weekend.)

Because they are always held where deals are to be had on hotels and convention space, it is not uncommon for them to get the entire convention center or a large portion of it. This turns out to be a temptation which most cons succumb to, but should not. The Montreal convention was huge and cavernous. It had little of the intimacy a mostly social event should have. Use of the entire convention center meant long walks and robbed the convention of a social center -- a single place through which you could expect people to flow, so you would see your friends, join up for hallway conversations and gather people to go for meals.

This is one of those cases where less can be more. You should not take more space than you need. The convention should be as initimate as it can be without becoming crowded. That may mean deliberately not taking function space.

A social center is vital to a good convention. Unfortunately when there are hotels in multiple directions from the convention center so that people use different exits, it is hard for the crowd to figure one out. At the Montreal convention (Anticipation) the closest thing to such a center was near the registration desk, but it never really worked. At other conventions, anywhere on the path to the primary entrance works. Sometimes it is the lobby and bar of the HQ hotel, but this was not the case here.

When the social center will not be obvious, the convention should try to find the best one, and put up a sign saying it is the congregation point. In some convention centers, meeting rooms will be on a different floor from other function space, and so it may be necessary to have two meeting points, one for in-between sessions, and the other for general time.

The social center/meeting point is the one thing it can make sense to use some space on. Expect a good fraction of the con to congregate there in break times. Let them form groups of conversation (there should be sound absorbing walls) but still be able to see and find other people in the space.

A good thing to make a meeting point work is to put up the schedule there, ideally in a dynamic way. This can be computer screens showing the titles of the upcoming sessions, or even human changed cards saying this. Anticipation used a giant schedule on the wall, which is also OK. The other methods allow descriptions to go up with the names. Anticipation did a roundly disliked "pocket" program printed on tabloid sized paper, with two pages usually needed to cover a whole day. Nobody had a pocket it could fit in. In addition, there were many changes to the schedule and the online version was not updated. Again, this is a volunteer effort, so I expect some glitches like this to happen, they are par for the course.