【正文】 ation over a range of about 50 metres. That range could, however, be extended if the devices in an area were configured to act as “platforms” that both receive and transmit signals. Messages would then hop from one platform to another until they got to their destination. That would allow such things as neighbourhood mobilephone panies and a plethora of radio and TV stations, and all for almost no cost. But to make such goodies work, CUWiN needs to tweak the underlying capabilities of WiFi chips in special ways.When its engineers requested the interface information from the firms that furnish the chips, however, they were often rebuffed. A few panies with lowend, older technology supplied it. But Broad and Atheros, the two producers of the sophisticated chips that CUWiN needs if its system is to sing properly, refused. Nor is CUWiN alone in its enforced ignorance. SeattleWireless and NYCwireless, among other groups, have similar ideas, but are similarly stymied. Christian Sandvig of the University of Illinois at UrbanaChampaign, who has been studying the brouhaha, believes regulators ought to enforce more openness.Broad and Atheros say that making the interface information public would be illegal, because it could allow users to change the parameters of a chip in ways that violate the rules for using unlicensed spectrum (for example, by increasing its power or changing its operating frequency). That is a worry, but it depends on rather a conservative interpretation of the law. The current rules apply to socalled “softwaredefined radios” (where the ability to send and receive signals is modifiable on the chip), and do not apply directly to WiFi. Also, by supplying the data, manufacturers would not be held liable if a user chose to tweak the chip in unlawful ways. And in any case, if the firms are really worried, they could release most of the interface, keeping back those features that are legally sensitive.Nor is the interface information mercially sensitive. Engineers are not asking for the puter code that drives the interfaces, merely for the means to talk to them. And having the interface information in the public domain should eventually result in more chips being sold. So it is hard to see what the problem is beyond a doginthemangerish desire not to give anything away. Time to open it up, boys.Passage 2Not as boring as you thoughtWatching paint dry may lead to some exciting new technologiesBelieve it or not, there are a small but significant number of people in this world who watch paint dry for a living. And watching paint dry, if you look closely enough, is fascinating. Honest. Plenty of researchers are enthralled by exactly how the paint es off the brush, how the polymers within it interact in order to adhere to a surface, and what happens when the water, or other solvent, evaporates. This sort of thing reveals how the chemistry really works, and thus how to make better paint.The excitement of watching a molecule of water lift off from the surface of a wall is, however, hampered by the fact that the only available photographs of the action are stills. It is like trying to work out how to play football from a series of timelapse frames. But help is at hand. Andrew Humphris, chief technology officer of Infinitesima, a small firm based in Bristol, in Britain, has e up with a system that allows you to take a movie of drying paint.The existing method of photographing molecules is more “feely” than “movie”. The camera is a device called an atomicforce microscope (AFM). This works by running the tip of a probe over the molecules in question, rather as the stylus of an oldfashioned record player runs across the surface of an LP. The bumps and grooves picked up by an AFM can be translated into a picture, but it takes between 30 seconds and a minute to build up an image. Scan much faster than that and the stylus starts to resonate, blurring the result.But Infinitesima39。s VideoAFM can, according to Dr Humphris, go 1,000 times faster than a standard AFM. That is fast enough to allow videos to be taken of, for example, molecules evaporating—information of great value to the paintmaking industry, to which Dr Humphris hopes to sell many of his machines. He is coy about exactly how they work, since the paper describing the details is awaiting publication in Applied Physics Letters. But the process for keeping the stylus under control seems to involve some highpowered puting and signal processing.Infinitesima is testing the VideoAFM by looking at polymers as they crystallise. The movies resemble frost spreading across a chilly window. But the VideoAFM can do more than mere analysis. It can do synthesis as well. Just as a carelessly applied stylus can alter the surfa