Summary of Un miliardo di anni fa in una galassia lontana lontana...

00:00:00 - 00:35:00

The first from the rest of the notes is a discussion about the discovery of gravitational waves in 2015 on September 14th by the Virgo experiment. This discovery was significant because it was the first time that gravitational waves had been directly observed, even though scientists had predicted their existence. Gravitational waves are moving ripples in space-time caused by violent cosmic events such as collisions between black holes. Despite detecting the signal, the Virgo machine was able to measure the masses of the black holes, which amounted to 62 times the mass of the sun. The second section discusses an incident during a space mission that occurred in October 1986, when the space shuttle Challenger exploded just 73 seconds after launch due to the failure of an O-ring seal in cold temperatures. Richard Feynman, a renowned scientist, played a crucial role in investigating the cause. The third section talks about how models in science can help us understand and predict complex systems. It uses the example of the water cycle and how scientists can build models of system behavior to predict the movement of water. The fourth section deals with the study of distant galaxies using telescopes and the limitations of capturing images of Earth. The fifth section discusses the concept of space curvature according to Einstein's general theory of relativity. It explains that mass or energy deforms space, which causes light to travel in a curved path. The last section is about the discovery and interpretation of gravitational waves.

• 00:00:00 In this section, the narrator discusses the discovery of gravitational waves, which were detected on September 14, 2015 by the Virgo experiment. The narrator explains that these waves were produced by the collision of two black holes, and although they did not directly observe the black holes, scientists were able to measure their masses. The narrator humorously mentions that the masses of the two black holes added up to 62 times that of the Sun, and compares this to the size of a children's book. The narrator then explains that the gravitational waves traveled a distance of 410 megaparsecs, approximately one billion light-years, and reflects on what was happening on Earth a billion years ago. The narrator uses the analogy of the space shuttle launches to explain the scientific method and concludes by mentioning the flight of the space shuttle Challenger in 1986, which attracted public attention due to the presence of a civilian teacher on board.
• 00:05:00 In this section, the speaker discusses an incident that occurred during a space mission, where an explosion in the engine caused the death of seven people. The incident halted the American space program until a commission was formed to investigate the cause. Richard Feynman, a renowned scientist, was part of this commission and played a crucial role in uncovering the truth. He discovered that a rubber seal had failed due to cold temperatures, leading to the explosion. The speaker highlights how this incident reflects the scientific method, where Feynman used theory and experimentation to understand what had happened. The speaker emphasizes the importance of theory and experimentation in scientific research, using the analogy of a hiker relying on a map to navigate a mountain.
• 00:10:00 In this section, the speaker discusses the concept of models in science and how they can be both descriptive and predictive. Using the example of the water cycle, the speaker explains how models can help us understand and predict the movement of water in rivers. They then move on to discuss the importance of asking questions in science and providing answers to those questions. They give the example of what stars and mountains are made of, with Kepler and Newton being pioneers in developing models to explain the movement of planets and the law of universal gravitation. The speaker also shows a famous photo taken by the Voyager spacecraft, highlighting the idea that even in a vast universe, scientific laws and models can be applied uniformly.
• 00:15:00 In this section, the speaker discusses the concept of using telescopes to observe distant galaxies and the limitations of capturing images of Earth. He explains that the most distant image of Earth captured so far is minuscule, appearing as just a tenth of a pixel. The speaker then moves on to discuss the study of spectroscopy and how it led to the development of quantum mechanics, which helps explain the behavior of atoms and the emission of light. From there, the speaker explains the concept of supernovas and how they are formed, leading to the possibility of the formation of neutron stars or black holes. Overall, this section provides insights into the study of distant galaxies, the behavior of light, and the formation of celestial objects.
• 00:20:00 In this section, the speaker discusses the concept of the curvature of space according to Albert Einstein's general theory of relativity. They explain that the presence of mass or energy deforms space, causing light to not travel in a straight line but instead follow the curvature. They use the analogy of a sheet that curves when a heavy object is placed on it to help visualize this idea. The speaker also mentions how this understanding of space curvature is used in GPS systems to accurately determine locations on Earth, as the satellites in orbit experience slower time due to their high speeds and the curvature of space-time.
• 00:25:00 In this section, the speaker discusses the concept of gravitational waves and how they are detected using interferometers. Gravitational waves are vibrations in the fabric of space-time, and their existence was predicted by Einstein's theory of general relativity. The speaker explains that the detection of these waves is challenging because the expected signal is extremely small, about a fraction of the size of an atom. Interferometers, such as the ones in the United States, are used to detect these waves by splitting a laser beam and interfering it in a way that cancels out any light unless a gravitational wave passes through and deforms the system. The speaker also mentions that there is a detector near Pisa, called Virgo, which has four kilometers long arms and can detect these tiny signals with high sensitivity.
• 00:30:00 In this section, the speaker discusses the discovery and interpretation of gravitational waves. In 2007, scientists predicted the existence of gravitational waves based on Einstein's general theory of relativity, but it wasn't until 2015, on September 14th, at around 11:00 am in Italy, that they were finally detected using two bracci located in Laser Interferometer Gravitational-Wave Observatory (LIGO) facilities in Louisiana and Washington. The signal observed was named GW150914, and was identified as a moving pair of black holes that collided with each other, causing ripples in spacetime. The discovery was significant because it confirmed a long-standing prediction in physics and opened up new opportunities for studying the universe. The speaker also emphasizes that the detection of gravitational waves was a fortunate event.
• 00:35:00 In this section, the speaker discusses the events that occurred in September, where the data collection was halted due to a signal interruption. Initially, they believed it was a test to see how people would react, but it turned into a chaotic day. The community found out a month later and the journalists, six months later, were able to keep it a secret. However, they plan to have two detectors in Germany and Italy functioning by 2025 and are working towards more advanced detectors in the future. They also mention the Lisa prototype, which is in orbit around Earth, and the possibility of having three larger detectors placed a million kilometers apart to improve precision in locating signals. They conclude by emphasizing that there is still much to discover and welcome aspiring scientists to join in the field of science.