The narrator is at a gold mine outside Melbourne, where scientists are installing a dark matter detector. Dark matter is thought to constitute 85% of all matter, and it's believed to form a shadow universe five times larger than our observable universe. Over the past several decades, numerous experiments have attempted to detect dark matter, but none have been successful except for one: DAMA/LIBRA, a dark matter detector located under a mountain in the Italian Alps. This detector has recorded peculiar results, with the rate of detections increasing to a peak in June and then decreasing to a minimum in November. Some scientists suggest this could be the first direct evidence of dark matter. However, the signal could also be due to other factors, such as temperature changes, humidity, or the number of tourists in Italy. To further test this hypothesis, an almost identical experiment is being built in the Southern hemisphere, in the gold mine outside Melbourne. This is because the solar system's motion through dark matter is the same in both hemispheres. If the same signal is observed, it would provide strong evidence for the existence of dark matter. However, the consensus is heavily in favor of dark matter being a physical substance, as it seems reasonable that there could be other particles out there that we haven't seen yet. The narrator concludes by expressing the hope that dark matter is not only one type of particle but a dark version of everything we can see, or perhaps something more complex due to its abundance.
Here are the key facts from the text:
1. The narrator is visiting a gold mine outside of Melbourne where a detector is being installed to search for dark matter.
2. The detector is located one kilometer underground, which takes 30 minutes to reach.
3. Dark matter is thought to make up 85% of all matter in existence.
4. Over 50 experiments have attempted to directly detect dark matter, but only one, DAMA/LIBRA, has reported a possible signal.
5. DAMA/LIBRA is located under a mountain in the Italian Alps and has been collecting data for around 20 years.
6. The detector has reported a periodic annual signal, with a peak in June and a minimum in November.
7. Scientists believe that this signal could be caused by the Earth's motion through dark matter.
8. The solar system is moving through the galaxy at 220 kilometers per second, and the Earth's orbit around the sun affects its motion through dark matter.
9. A new experiment is being built in the Southern hemisphere to replicate the results of DAMA/LIBRA and determine if the signal is due to dark matter.
10. The new experiment is located in a gold mine outside of Melbourne, where the seasons are reversed but the motion through dark matter is the same.
11. If the new experiment sees the same signal as DAMA/LIBRA, it will be strong evidence for the existence of dark matter.
12. The concept of dark matter was first proposed by Swiss astronomer Fritz Zwicky in 1933.
13. Zwicky observed that the orbital speeds of galaxies in the coma cluster were higher than expected, suggesting that there was a large amount of unseen mass.
14. Vera Ruben and Kent Ford later observed the motion of stars in the Andromeda Galaxy and found that the rotational velocity remained constant with increasing distance from the center.
15. This observation suggests that there is a large amount of unseen mass in the galaxy, which is not visible or interacting with light.
16. The rotation curves of galaxies can be explained by the presence of dark matter, which provides the necessary gravitational attraction to hold the galaxy together.
17. The existence of dark matter is also supported by the observation of gravitational lensing, which shows that there is a large amount of mass in the universe that is not visible.
18. The cosmic microwave background radiation also provides evidence for dark matter, as the fluctuations in the radiation can be explained by the presence of dark matter.
19. The detector at the bottom of the gold mine is looking for WIMPs (weakly interacting massive particles), which are thought to be the particles that make up dark matter.
20. The detector uses crystals of pure sodium iodide to detect the scintillation caused by dark matter particles interacting with the crystal.
21. The detector is shielded by 120 tons of steel and plastic to reduce background noise and radiation.
22. The experiment is expected to take several years to complete and will provide evidence for or against the existence of dark matter.
23. The discovery of dark matter would be a major breakthrough in physics and would help to explain many of the observed phenomena in the universe.