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Renewable energy comes from naturally replenished resources such as sunlight, wind, flowing water, geothermal heat, and sustainable biomass, helping power electricity, heat, transport, and industry while reducing dependence on fossil fuels.
Renaissance art refers to the painting, sculpture, architecture, and design that flourished in Italy and then across Europe from the fourteenth through the sixteenth centuries. It combined renewed interest in ancient Greek and Roman culture with close observation of nature, mathematical perspective, human-centered storytelling, religious devotion, political ambition, and new ideas about the artist as an intellectual creator.
Recycling collects and processes materials that would otherwise become waste, turning them into inputs for new products. It can conserve resources, save energy, reduce landfill use, and support jobs, but it works best as part of a larger waste hierarchy that prioritizes reducing, reusing, repairing, and buying durable goods first.
Radioactivity is the spontaneous decay of unstable atomic nuclei, releasing particles or energy as atoms transform toward more stable forms, with uses in medicine, dating, energy, industry, research, and radiation protection.
Rabbits are small lagomorph mammals known for powerful hind legs, fast breeding, plant-based diets, and a long history as wild animals, domestic animals, and ecological actors.
Quantum physics studies matter, energy, particles, and fields at scales where classical intuition breaks down. It explains why atoms are stable, why light can arrive in packets, why outcomes are often probabilistic, and why modern tools such as lasers, transistors, atomic clocks, MRI, and quantum computers are possible.
Quantum computing is a computing approach that uses quantum-mechanical systems as information carriers. It is being developed for problems where carefully controlled qubits may eventually help with simulation, optimization, chemistry, materials, and cryptography-related tasks.
Qualcomm is a semiconductor and wireless technology company known for Snapdragon mobile platforms, 5G modems, cellular patents, radio-frequency systems, automotive chips, IoT products, and edge AI features used across phones and connected devices.
The Pyramids of Giza are the monumental royal tombs of Old Kingdom Egypt on the Giza Plateau near Cairo, built for the Fourth Dynasty kings Khufu, Khafre, and Menkaure and surrounded by temples, causeways, cemeteries, and the Great Sphinx.
Public transportation is shared mobility available to the public through systems such as buses, trains, metros, trams, ferries, and demand-responsive services. It connects people to jobs, education, health care, shopping, culture, and one another, while shaping city growth, emissions, equity, and daily time.
Public health is the organized work of protecting and improving health at the population level, using prevention, data, policy, communication, services, and community action to reduce disease, injury, and health inequity.
Public goods are goods or services that people cannot easily be excluded from using and whose use by one person does not greatly reduce use by others. They help explain why markets may underprovide some valuable shared benefits.
The printing press changed how knowledge moved. By combining movable metal type, oil-based ink, paper, and a press mechanism, printers could produce many copies of a text faster and more consistently than hand copying, helping books, pamphlets, maps, religious arguments, scientific diagrams, and news travel across societies.
Pompeii was a Roman city near the Bay of Naples that was buried when Mount Vesuvius erupted in 79 CE. Its sudden destruction preserved streets, homes, shops, paintings, inscriptions, food remains, and human traces, making Pompeii one of the most important windows into everyday life in the Roman world.
Plate tectonics is the theory that Earth's rigid outer shell is broken into moving plates whose boundaries create many earthquakes, volcanoes, mountain ranges, trenches, mid-ocean ridges, and long-term changes in continents and ocean basins.
Photosynthesis is the process that uses light energy to convert carbon dioxide and water into sugars while releasing oxygen. It powers plants, algae, many microbes, food webs, oxygen in the atmosphere, and part of Earth?s carbon cycle, making it one of the most important biological processes on the planet.
Philosophy is the disciplined practice of asking fundamental questions about what exists, what we can know, how reasoning works, what makes actions right or wrong, what gives life meaning, and how people should live together. It turns ordinary assumptions into ideas that can be examined, challenged, improved, and used more carefully.
Petra is an ancient city in southern Jordan, carved into sandstone cliffs and shaped by Nabataean trade, engineering, and religious life. Famous for the narrow Siq and the facade called the Treasury, Petra was also a living city of tombs, temples, water channels, markets, houses, roads, and later Roman and Byzantine layers.
Permeable pavement lets rain and snowmelt pass through a hard surface into stone, soil, or an underdrain below. It can reduce runoff, store stormwater near where it falls, and filter some pollutants when it is designed, installed, and maintained well.
The periodic table is the organized chart of chemical elements, arranged mainly by atomic number so that patterns in electron structure, reactivity, bonding, and physical properties become visible across rows and columns.
PayPal is a financial technology company known for digital wallets, online checkout, peer-to-peer payments through Venmo, merchant services, cards, fraud prevention, risk systems, and cross-border money movement for consumers and businesses.
The Parthenon is the ancient temple on the Acropolis of Athens, built for Athena in the fifth century BCE and remembered for its architecture, sculpture, political symbolism, later transformations, damage, restoration, and debates over cultural heritage.
The Panama Canal is the lock-based waterway across the Isthmus of Panama that connects the Atlantic and Pacific oceans, reshaping global trade through engineering, disease control, political conflict, sovereignty struggles, and freshwater management.
The Ottoman Empire was a long-lived empire founded by a Turkish dynasty in Anatolia around 1300. It grew into a major power across southeastern Europe, Anatolia, the Middle East, North Africa, and the eastern Mediterranean, ruled from Istanbul after 1453, and ended after World War I as the Republic of Turkey and other successor states emerged.
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