Enlarge / The LISA project will consist of three spacecraft in a triangular configuration, exchanging lasers. (credit: EADS Astrium)

On Thursday, the European Space Agency's Science Programme Committee gave the go-ahead to the Laser Interferometer Space Antenna, or LISA project. This would mean the construction of the mission's three spacecraft could begin as early as a year from now. While the interferometer would follow the same basic principles as the ground-based LIGO (Laser Interferometer Gravitational-Wave Observatory) experiment that first detected gravitational waves, the hardware would be placed 2.5 million kilometers apart, making it sensitive to an entirely new range of astronomical phenomena.

Proven tech

Existing gravitational wave detectors rely on bouncing lasers back and forth between distant mirrors before recombining them to produce an interference pattern. Anything that alters the position of the mirrors—from the rumble of a large truck to the passing of gravitational waves—will change the interference pattern. Having detectors at distant sites helps us eliminate cases of local noise, allowing us to detect astronomical events.

The detectors we've built on Earth have successfully picked up gravitational waves generated by the mergers of compact objects like neutron stars and black holes. But their relatively compact size means that they can only capture high-frequency gravitational waves, which are only produced in the last few seconds before a merger takes place.

Enlarge (credit: Benj Edwards / Jonathan Zufi / Apple)

Forty years ago today, Apple released the first Macintosh. Since that fateful day in 1984, Apple has released hundreds of Mac models that run the gamut from amazing to strange. In honor of this birthday, we thought it would be fun to comb through history and pull out the rarest and most unusual production Mac models ever made—including one from another company.

Each machine listed below was manufactured and sold to the public—no prototypes here. These computers highlight not only Apple's innovative spirit but also its willingness to take risks and experiment with design and functionality. It's worth noting that what is "weird" in this case is a matter of opinion, so you might have your own personal picks that we missed. If that's the case, let us know in the comments. And we'd love to hear what the Macintosh means to you on this 40th anniversary.

Special thanks to Jonathan Zufi for providing several photos for this article. In 2014, Zufi created an excellent coffee table book called Iconic: A Photographic Tribute to Apple Innovation and formerly ran the Shrine of Apple website.

Enlarge / A tiny fleck of paint, taken from the Mona Lisa, is revealing insights into previously unknown steps of Leonardo da Vinci's process. (credit: Public domain)

When Leonardo da Vinci was creating his masterpiece, the Mona Lisa, he may have experimented with lead oxide in his base layer, resulting in trace amounts of a compound called plumbonacrite. It forms when lead oxides combine with oil, a common mixture to help paint dry, used by later artists like Rembrandt. But the presence of plumbonacrite in the Mona Lisa is the first time the compound has been detected in an Italian Renaissance painting, suggesting that da Vinci could have pioneered this technique, according to the authors of a recent paper published in the Journal of the American Chemical Society.

Fewer than 20 of da Vinci's paintings have survived, and the Mona Lisa is by far the most famous, inspiring a 1950s hit song by Nat King Cole and featuring prominently in last year's Glass Onion: a Knives Out Mystery, among other pop culture mentions. The painting is in remarkably good condition given its age, but art conservationists and da Vinci scholars alike are eager to learn as much as possible about the materials the Renaissance master used to create his works.

There have been some recent scientific investigations of da Vinci's works, which revealed that he varied the materials used for his paintings, especially concerning the ground layers applied between the wooden panel surface and the subsequent paint layers. For instance, for his Virgin and Child with St. Anne (c. 1503–1519), he used a typical Italian Renaissance gesso for the ground layer, followed by a lead white priming layer. But for La Belle Ferronniere (c. 1495–1497), da Vinci used an oil-based ground layer made of white and red lead.