Speed of light they appeared 13 billion years ago, when the universe was less than a billion years old. The fact that more distant objects appear to be younger, due to the finite speed of light, allows astronomers to infer the evolution of stars, of galaxies, and of the universe itself. Astronomical distances are sometimes expressed in light-years, especially in popular science publications and media. A light-year is the distance light travels in one year, around 9461 billion kilometres, 5879 billion miles, or 0.3066 parsecs. In round figures, a light year is nearly 10 trillion kilometres or nearly 6 trillion miles. Proxima Centauri,
2-in-1 PC 2-in-1 PC A 2-in-1 PC, also known as a 2-in-1 tablet, 2-in-1 laptop, 2-in-1 detachable, laplet, tabtop, laptop tablet, or simply 2-in-1, is a portable computer that has features of both tablets and laptops. Before the emergence of "2-in-1s" and their denomination as such, technology journalists used the words "convertible" and "hybrid" to denominate pre-2-in-1 portable computers: "Convertible" typically denominated those that featured a mechanism to conceal the physical keyboard by sliding or rotating it behind the chassis, and "hybrid" those that featured a hot-pluggable, complementary, physical keyboard. Both pre-2-in-1 convertibles and hybrids were crossover devices that combined features of