Are We Alone in the Universe?
Anyone trying to answer questions like “What is life?” and “Are we alone?” is inevitably limited by what we know: the only major type of life we know of or have studied so far exists only on Earth. But life on exoplanets may look and function differently than anything ever observed before, and to continue searching for life there, we need to acknowledge our tendency to be shortsighted. Long ago, before the advent of DNA sequencing and other biotechnologies, we used to divide life into two categories: plants and animals. But we have since learned that the diversity of single-celled and multicellular organisms on this planet is astonishing. Despite this, all known life forms on Earth, including animals, plants, protists, fungi, archaea, and bacteria, share a common basic chemical structure: they are all built on a backbone of carbon atoms. It is understandable, therefore, that people assume that all organisms must be built this way—that all life is carbon-based, just like life forms in our world.
The birth of human civilization
Are there still habitable environments in the universe?
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Popular ScienceDeep-sea discoveries reveal ancient secrets
Students who love ancient civilizations should know that the earliest human civilization is believed to have originated from the Sumerians in the Mesopotamian Basin. The Sumerian civilization, which invented cuneiform, is about 8,000 years old. After more than 3,000 years, it was replaced by the Babylonian civilization. However, at the end of the last century, an underwater relic discovered near the Ryukyu Islands in Japan is likely to completely subvert the cognition of human civilization.What secrets are hidden in this suspicious deep-sea relic? In the southernmost part of Japan, further south than Okinawa Island, there is a small island called Yonaguni. The island is located at the westernmost end of the Yaeyama Islands in the Ryukyu Islands. From the map, it is on the edge of the continental shelf, only one step away from Taiwan Island. Yonaguni Island has an area of about 28.88 square kilometers, a coastline of about 28 kilometers, a population of about 1,745, and an average annual temperature of 23.9℃. Due to the strong southerly wind blowing on the island all year round, the erosion of the southern coast is more obvious, and most of them are cliffs. Nishizaki in the west is the westernmost cape of Japan, and there is a monument that reads "Japan - the westernmost place - Yonaguni Island".
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Popular ScienceThe Arctic Is Melting Faster Than Expected
The Arctic could see its first ice-free summer day by 2027, exacerbating global warming and extreme weather. The Arctic could see its first summer as early as 2027, with nearly all of its sea ice melted away — a troubling milestone for the planet. For the first time, an international team of researchers, led by the University of Colorado and the University of Gothenburg in Sweden, used computer models to predict when the northernmost ocean would see its first ice-free day. An ice-free Arctic could have major impacts on ecosystems and Earth’s climate by altering weather patterns.
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Popular ScienceIs smell your most powerful memory trigger?
Have you ever had a smell that has touched you so deeply that you still can't forget it? I believe many people have had such an experience. In fact, 75% of human emotions are closely connected to the sense of smell, which can be called a loyal guardian of memory. Each smell may carry a unique memory story, and they are like a portal in time, leading us to travel through time and space and return to the past.
