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The user wants a concise summary of a transcript of a video about the detection of gravitational waves with pulsar timing arrays. The summary could be:
The video explains how astrophysicists have found evidence for very low frequency gravitational waves that are light years long, using pulsars as precise clocks. The video compares these waves to the ones detected by LIGO, which are much higher frequency and come from merging black holes. The video also discusses the possible sources of these long waves, such as pairs of supermassive black holes, inflation, cosmic strings, or phase transitions in the early universe. The video highlights the challenges and implications of this discovery, which could open the door to studying the very first moments of the universe's history.
1. Astrophysicists have found evidence for gravitational waves that are light years long and have very low frequencies. These are ripples through space itself caused by cataclysmic events and massive objects.
2. The detection of these gravitational waves occurred in 2017, and they were longer than those detected previously, with wavelengths of kilometers and much higher frequencies.
3. The gravitational waves detected in 2017 were believed to be caused by the merger of two black holes that were a few tens of times heavier than the Sun.
4. The new evidence published this month suggests that the cause of the much longer wavelength gravitational waves is not a hundred percent certain. The best guess is that it's pairs of supermassive black holes that are spiraling around each other on their way to merging.
5. Supermassive black holes are described as being anywhere from a million to tens of billion times more massive than the Sun.
6. The data released this month suggests that there could be some new physics involved, as the cause of the gravitational waves might not be supermassive black holes merging.
7. The evidence for these gravitational waves has been found with Pulsar timing arrays. Pulsars are spinning neutron stars, and they are incredibly precise.
8. The separation between the pulsars in the timing array is so large (Light Years) that it makes the scientists sensitive to different frequencies of gravitational waves.
9. The gravitational waves detected by the Pulsar timing array have wavelengths of tens of light years, meaning that they are very different from the gravitational waves detected by LIGO (Laser Interferometer Gravitational-Wave Observatory), which are much higher frequencies with wavelengths around about tens of kilometers.
10. The evidence from the Pulsar timing array comes from the fact that this background signal causes correlations in your Pulsar timing array data specifically something known as the Hellings Downs correlation.
11. The background signal causes correlations in the data is shown by the blue line and the sort of shaded region around it is your uncertainty.
12. The data shows that the correlation in the data is shown by the blue line and the sort of shaded region around it is your uncertainty.
13. The black dashed line shows the shape that you'd expect from the Hellings Downs correlation and it's a pretty good fit.
14. The data from all the Pulsar timing array collaborations show a fit to the black dashed line, indicating evidence for the gravitational wave background signal.
15. The concept of pairs of supermassive black holes is adding nothing new to our current models of the universe, and it's always going to be the first point of call.
16. The only option left is to start considering some new physics that might explain this background signal.
17. The only option left is to start considering some new physics that might explain this background signal. Hypothetical ideas include inflation, cosmic strings, and phase transitions.
18. The Bayes factor is used to determine how likely a model is to explain the data. The inflation-related model and the cosmic string-related model are some of the strongest candidates for new physics.
19. The gravitational wave background signal appears to be isotropic, the same in all directions. This suggests it's some new physics.
20. The Pulsar timing array collaborations are now ready to combine their data sets to test this further.