Do magnets lose energy?

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Well, we all know magnets lose energy by colliding with the outside world. But does their loss vary by size? To find out, we asked scientists at Northwestern University:

Will magnets lose energy at a smaller scale?

If you are wondering why we need to know to answer that question, take a look at this table:

Image: Northwestern University

In response to last week’s revelation by Edward Snowden, a New York Times article details the existence of a highly classified NSA program in which the U.S. collects bulk communications data from U.S. Internet companies, the Guardian reports that the program, known as PRISM, “has also helped the government track the online activities of thousands of foreign persons.”

The program uses a U.S. tech giant, Google, as a base: According to the article, from 2008 to 2010, the NSA worked to “break into as many as a half-dozen Google systems across the world, including in Germany and Brazil, allowing it to monitor the communications of tens of thousands of users at any given time.” The Guardian is citing information from an anonymous NSA official.

As the author of the article explains, this isn’t merely a problem for countries that violate the international treaty against mass surveillance (“we did not target people in Germany, and we have no evidence that anyone has been wrongly targeted in Brazil or Germany. However, it is possible that some users may have been unintentionally caught up in the sweep.”), but an issue of basic infrastructure security, pointing to the fact that Google “has not disclosed how it works to protect its network infrastructure from hackers, according to its site.”

The Guardian then describes a second system, codenamed Boundless Informant, which is “an automated program that mines communications records for a particular keyword or phrases, and then attempts to associate the keywords or phrases with Internet address records of a single account.”

The article also details how the “bulk-collection system, used in partnership with a variety of private Internet firms, has also been used to target the communications of thousands of foreigners abroad, including those in the United States.” The Guardian notes, “The collection of telephone call records and emails is a particularly sensitive area, since a small fraction of foreigners are on U.S. soil.”

The Guardian’s article continues, “Other methods of targeting foreign targets and gaining access to their overseas accounts were revealed last weekend when the Guardian, citing documents provided by Mr Snowden, reported on the existence of