24. Ripples of Space and Time
Welcome to listen to the discussion on the history of science. Hawking wrote a new book called "The Grand Design," in which he mentioned the analogy of a goldfish in a fish tank. If the fish is inside the fish tank, it sees the external world as distorted, making it seem unreal. Physicists today are like the goldfish in the tank, unsure if the universe's space is curved or not. Is the universe bent or straight? If the space is curved, is pi still equal to 3.14159? On Earth, the equator makes the Earth a sphere. Is the circumference approximately twice the diameter? These questions lead to the discussion of how to determine if space is curved. Physicists use intricate methods, such as interferometers, to measure and detect any disturbances in the space-time continuum, like gravitational waves. Interferometers are devices that use two perpendicular laser beams to form interference patterns. If the space-time is distorted by a gravitational wave, the path of light is altered, allowing physicists to measure the effect. To increase sensitivity, the length of the laser beams must be extended, as demonstrated in the LIGO observatories in the United States. By having two observatories located far apart, physicists can differentiate between noise and valid signals from gravitational waves. Collecting data since 2003, LIGO is the most significant and sensitive gravitational wave detector globally, with plans for further upgrades to increase sensitivity. However, increasing sensitivity and maintaining interferometers are costly, leading to suggestions for other countries, such as China, to invest in interferometers due to their increasing financial stability. Although the cost and complexity of these instruments are high, they remain essential for scientific research and exploration. The potential for a global collaboration in detecting and studying gravitational waves remains promising, with the hope of expanding our understanding of the universe and its mysteries.