00:00NASA's Fermi Gamma-ray Space Telescope watches the sky for gamma rays, the highest energy form of light.
00:08These detections help scientists learn more about the most powerful events in the cosmos.
00:13However, a recent absence of gamma ray detection may have been just as informative.
00:19Cosmic rays are small particles like protons and helium nuclei traveling at nearly the speed of light.
00:26It takes a lot of energy to accelerate them to that speed, so scientists assume they're driven by powerful events like exploding stars, called supernovae.
00:36Because cosmic rays are charged particles, they interact with magnetic fields as they travel.
00:41These interactions mean they don't follow a straight line from their sources, and so scientists can't trace where they came from.
00:48But when cosmic rays smash into other particles, they produce gamma rays.
00:53And gamma rays do travel to us straight from their sources.
00:57Fermi has even detected such gamma rays from supernova remnants, which are thousands of years old.
01:03If supernovae and their remnants really are a key source of cosmic rays, then calculations tell astronomers how many gamma rays Fermi should detect.
01:12But so far, the telescope hasn't seen enough gamma rays from these sources.
01:17Scientists had suspected this was because the supernovae were too far away, or observations began too late, well after peak production.
01:27In May 2023, Fermi observed the most luminous nearby supernova seen since the mission launched 15 years ago.
01:35It captured data from the first few weeks of the explosion, when scientists anticipated the greatest production of cosmic rays.
01:43But Fermi didn't see any gamma rays from the explosion.
01:47Scientists aren't yet sure what this means for the link between cosmic rays and supernovae.
01:52There's still a lot of work left to do.
01:54But Fermi's non-detection has added a very important new piece to this high-energy puzzle.
02:00A very important new project was launched in the world's thermostatic phase of BlueCast.
02:04That's how you put it in the world's energy.
02:06So, we'll be find out our world's energy in the world's energy.
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