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Did you know that a child's cells can live and breathe inside a mother's body for a lifetime, even after childbirth? This phenomenon is called 'fetal microchimerism'. During pregnancy, fetal stem cells travel through the umbilical cord into the mother's bloodstream. These cells don't disappear after birth; they migrate to the mother's heart, liver, and even brain, living together for decades. What's even more amazing is what happens when the mother's organs are damaged. The child's cells remaining in her body rush to the injured site, transform into the needed cells, and help with healing. Just as a mother cherishes and raises her child, the cells left behind by the child remain in the mother's body, protecting her for life.

- Cause of Seasonal Changes Due to the Earth's axis being tilted at 23.5 degrees while revolving around the sun, the sun's altitude changes. As the solar energy received increases and decreases accordingly, seasonal changes occur. - Definition of Meteorological Seasons (Based on Korea Meteorological Administration) Spring: The first day the average temperature exceeds 5°C Summer: The first day the average temperature exceeds 20°C Autumn: The first day the average temperature drops below 20°C Winter: The first day the average temperature drops below 5°C However, even if the temperature reaches 5°C or 20°C, they don't immediately announce a seasonal change. Instead, they use a 9-day moving average, meaning they announce the seasonal change based on the first day the threshold is reached using 9 days of weather data. The reason for using a 9-day moving average is to remove errors caused by temporary temperature fluctuations. Temperature standards vary by country. For example, China uses 10°C and 22°C as their standards. They also use a 5-day moving average. So, the conclusion is that autumn hasn't arrived in South Korea yet, except for high-altitude areas.

The reason the sun emits light is due to hydrogen fusion. However, calculations based on classical physics show that the temperature at the sun's core is far too low to initiate fusion. This is because there isn't enough energy to overcome the strong electromagnetic force pushing protons apart. According to theory, the sun should have cooled down to blackness without ever igniting. What turned this impossibility into a possibility is 'quantum tunneling'. Particles in the microscopic world have a probability of passing through energy barriers like ghosts. As protons fuse by overcoming these barriers with an extremely slim chance, they emit immense light. The warm sunlight we feel every day is actually a miracle brought about by quantum mechanics.

Tropical cyclones that occur in the Northwest Pacific. Water vapor evaporated from the warm sea forms updrafts, starting their development and creating a low-pressure area. Afterward, they cause natural disasters accompanied by wind and rain wherever they pass. - Names by Region of Occurrence Typhoon: Northwest Pacific (west of the International Date Line) Hurricane: Northeast Pacific (east of the International Date Line), Atlantic Ocean Cyclone: South Pacific, Indian Ocean + Mediterranean Sea - Naming Convention for Typhoons 14 countries that suffer major damage from typhoons form a Typhoon Committee. Each country submits 10 names, totaling 140 names, which are used sequentially. About 20-25 typhoons occur per year, and the list of names is completely used up in about 5-6 years, after which it returns to the beginning and reuses the names. The order is based on the alphabetical order of the submitting countries: Cambodia, China, North Korea, Hong Kong, Japan, Laos, Macau, Malaysia, Micronesia, Philippines, South Korea, Thailand, USA (Guam), Vietnam. However, typhoons that cause significant damage are decertified and replaced with a different name.

Behind the secret of how birds migrate thousands of kilometers every year without getting lost lies quantum mechanics. Inside the eyes of migratory birds like robins, there's a special protein called 'cryptochrome.' When exposed to light, electrons move within this protein, creating pairs of electrons in a state of 'quantum entanglement.' This subtle quantum state reacts to the Earth's weak magnetic field, generating dark or bright visual patterns in the bird's vision. In essence, birds aren't just looking at a compass; they are literally 'seeing' the direction of the compass with their eyes. The phenomenon of quantum entanglement, once only seen in advanced physics labs, has been utilized by birds in nature for survival for millions of years.

The Navier-Stokes equations are partial differential equations that describe the motion of fluid substances, such as water or air. They apply Newton's second law of motion to fluid dynamics, relating the fluid's velocity, pressure, density, and temperature. In their most common form, they describe the motion of a viscous fluid and include terms for inertia, pressure gradients, viscous forces, and external body forces like gravity. For viscous, incompressible fluids, the change in velocity field determines the flow and pressure distribution, and complex turbulence can arise depending on the conditions. Due to the nonlinear nature of fluid motion, small differences in initial conditions can lead to vastly different outcomes, making solutions very difficult to obtain. These equations are used to analyze phenomena such as airflow around wings, weather and ocean currents, blood flow, and fluid dynamics in pipes. The problem of proving whether smooth solutions exist for the 3D incompressible Navier-Stokes equations is one of the Millennium Prize Problems and remains unsolved for the general case.

When KTX was established, there were three main plans for the high-speed rail construction in the Seoul area: 1. Undergrounding all the way to Seoul Station. 2. Building a new station in the Seoul Gangnam area and undergrounding. 3. Building the high-speed line up to the outskirts of Seoul and utilizing existing lines within the city. Plans 1 and 2 required undergrounding due to the urban areas, but due to the financial difficulties of the IMF crisis during the construction period, the costly undergrounding was abandoned. Instead, Plan 3, which involved building the high-speed line only to the outskirts of Seoul (Gwangmyeong Station), was finalized. Furthermore, Gwangmyeong Station was planned to handle a significant portion of the terminal services, and it was built large and grand enough to be called 'Gwangmyeong Airport.' However, due to public complaints about inconvenience because it wasn't in downtown Seoul, the plan was changed to concentrate terminal services at the current Seoul and Yongsan stations. The saturation of Seoul's rail capacity became an added issue. However, the initial plans weren't entirely discarded. To alleviate the rail capacity issues, Plan 2 was revived as the Suseo-Pyeongtaek High-Speed Line, departing from the current Suseo Station. Plan 1 was revived recently as the Susek-Gwangmyeong High-Speed Line, and construction was confirmed to begin this August, with an expected opening in 2036.

Where do you think the coldest place in the universe is? It's easy to imagine the edge of the solar system or interstellar space, but the answer is actually inside a research lab on Earth. The naturally coldest place in space is the Boomerang Nebula, reaching about -272°C (1K absolute temperature). However, humans have succeeded in creating ultra-low temperatures in labs, close to absolute zero at below -273.14°C, or in the nanokelvin (nK) range, using laser cooling technology. In reality, a corner of a physics lab in Korea or around the world is much colder than the pitch-black void of deep space. Isn't it fascinating that humans are directly recreating the most extreme cosmic environments right here on the ground?

I'm a high school senior preparing for the college entrance exam, so I might not be able to post as often or at all until then! Please keep this in mind.

When you stir your teacup with a spoon, where do the tea leaves gather? You might think they'd be pushed to the edge by centrifugal force, but they actually collect in a neat pile right in the center at the bottom. In fluid dynamics, this is called the 'tea leaf paradox'. Albert Einstein brilliantly explained this peculiar phenomenon. When water rotates, friction with the bottom of the cup slows down the flow, creating a pressure difference. As a result, a subtle flow called 'secondary flow' emerges at the bottom, pulling water from the edges towards the center. It's precisely this bottom flow that sweeps the heavier tea leaves into the cup's center. The magic of friction overcoming the seemingly obvious centrifugal force – astonishing fluid dynamics are hidden even in an ordinary teacup.