Since our ancient human relatives began using stone tools to perform tasks, humans have harnessed scientific knowledge and new technologies to expand the boundaries of our understanding of the natural world. From quantum computing and microplastics to artificial intelligence and memory, explore these topics and more with our concise yet informative overviews and expert-curated resources.
Hours of research by our editors, distilled into minutes of clarity.
Although 3D printing has become synonymous with the term, objects can be fabricated without filaments of hot plastic or light-sensitive powders. For example, during sheet lamination, ultrasonic waves—high-frequency vibrations—can join metal sheets by creating molecular bonds through friction.
Nupedia was launched in 2000 by internet entrepreneur Jimmy Wales and internet project developer Lawrence Sanger, only publishing articles written by experts after a cumbersome seven-step review process. The two developed Wikipedia to allow the public to write articles for future review, but shifting to self-moderation contributed to Sanger's departure in 2002.
The first working 3D printing device was invented in 1983 and utilized stereolithography, a process in which a laser triggers a chemical reaction that hardens liquid resin. Powder-based laser sintering technology was patented in 1987, with metal-based powders first being used for 3D printing in 1997.
The near-infrared and ultraviolet light captured by the space telescope is not visible to human eyes, but observational data of these types of light can be filtered and modified into visible colors. Many detailed images of astronomical objects are the result of combining these artificially colored images into layers.
When electricity from a battery passes through the crystal inside a watch, the crystal vibrates, creating an electrical signal with a precise frequency of one vibration per second. This signal moves the hand of the watch so that it ticks once per second, allowing it to track the passage of time.
Although time is considered a fixed, ordered mapping of events, where the past affects the future, quantum superposition breaks down causality, suggesting that future events can occur simultaneously with past ones. Within the quantum model, the notion of cause and effect is not a fundamental feature of our universe.
Hydrogen, present since the early universe, serves as fuel for the proton-proton chain, producing helium, which is then incorporated into the CNO cycle to produce carbon, nitrogen, and oxygen. Additional fusions of helium with these elements and subsequent decays via the alpha ladder produce elements up to iron and bismuth.
The most important figure in the effort to create what would become the Hubble Space Telescope was Lyman Spitzer, who first proposed a telescope in orbit in 1946. The nearly 50-year endeavor led to space-based observatories, which are not limited by Earth's atmosphere absorbing or distorting most wavelengths of light.
3D printing food requires integrating ingredients with a variety of properties, which may not all resist the physical stress of stacking. This means successful 3D printing of food may require rethinking how ingredients are layered and modifying ratios of each, potentially sacrificing taste for structural integrity.
Colorblind artist Neil Harbisson was born into a world of grey. In 2004, he had a chip installed connected to an external color frequency sensor. Once the sensor "reads" a color, it sends a signal to the chip and plays an associated sound both in and outside Harbisson's head.
