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Should you trust the world's first user-generated encyclopedia?

5 min read

Wikipedia users who logged on to the free online encyclopedia this January to do research on current members of the U.S. Congress may have been surprised to encounter the online equivalent of a playground shouting match. The official entry for Rep. Eric I. Cantor (R-Va.) noted that he smelled of "cow dung," and the blurb for Sen. Tom Coburn (R-Okla.) mentioned a dubious-sounding biographical detail: "Coburn was voted the most annoying senator by his peers in Congress. This was due to Senator Coburn being a huge douche bag."

Within hours, Wikipedia administrators had intercepted the renegade edits--but not before the incident provoked a nationwide media furor, spurring questions about the encyclopedia's credibility. As the first-ever major reference work with a democratic premise--that anyone can contribute an article or edit an entry--Wikipedia has generated shared scholarly efforts to rival those of any literary or philosophical movement in history. Its signature strength, however, is also its greatest vulnerability. User-generated articles are often inaccurate or irrelevant, and vandals like the political jokesters are a constant threat. As a result, the role of the encyclopedia's gatekeepers assumes added importance. Who are they, and how do they go about the business of deciding which new content will pass through their crucible?

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Metamaterials Could Solve One of 6G’s Big Problems

There’s plenty of bandwidth available if we use reconfigurable intelligent surfaces

12 min read
An illustration depicting cellphone users at street level in a city, with wireless signals reaching them via reflecting surfaces.

Ground level in a typical urban canyon, shielded by tall buildings, will be inaccessible to some 6G frequencies. Deft placement of reconfigurable intelligent surfaces [yellow] will enable the signals to pervade these areas.

Chris Philpot

For all the tumultuous revolution in wireless technology over the past several decades, there have been a couple of constants. One is the overcrowding of radio bands, and the other is the move to escape that congestion by exploiting higher and higher frequencies. And today, as engineers roll out 5G and plan for 6G wireless, they find themselves at a crossroads: After years of designing superefficient transmitters and receivers, and of compensating for the signal losses at the end points of a radio channel, they’re beginning to realize that they are approaching the practical limits of transmitter and receiver efficiency. From now on, to get high performance as we go to higher frequencies, we will need to engineer the wireless channel itself. But how can we possibly engineer and control a wireless environment, which is determined by a host of factors, many of them random and therefore unpredictable?

Perhaps the most promising solution, right now, is to use reconfigurable intelligent surfaces. These are planar structures typically ranging in size from about 100 square centimeters to about 5 square meters or more, depending on the frequency and other factors. These surfaces use advanced substances called metamaterials to reflect and refract electromagnetic waves. Thin two-dimensional metamaterials, known as metasurfaces, can be designed to sense the local electromagnetic environment and tune the wave’s key properties, such as its amplitude, phase, and polarization, as the wave is reflected or refracted by the surface. So as the waves fall on such a surface, it can alter the incident waves’ direction so as to strengthen the channel. In fact, these metasurfaces can be programmed to make these changes dynamically, reconfiguring the signal in real time in response to changes in the wireless channel. Think of reconfigurable intelligent surfaces as the next evolution of the repeater concept.

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