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The Biggest Weirdest Telescope We've Ever Built

2023-07-21 · explainer · Hank · 8:27 · watch on YouTube

Topic: Science & nature · mode: News analysis · tags: timely hook

Hank explains that astronomy has relied only on photons until two recent breakthroughs: pulsar timing that detected the gravitational wave background, and the IceCube Neutrino Observatory in Antarctic ice, which used machine learning to make the first map of our galaxy not based on photons.

What is said

The parts of the video and what is said in each (★ — how much it matters to the video).

00:00:00 — Hank gives up on the hat; astronomy has only ever used photons (Galileo, Jocelyn Bell Burnell)

  • ★ Hank tells John he has given up on wearing a hat. (playful) — 00:00:00
  • ★★ Hank says that for all of human history the only tool for astronomy has been the electromagnetic spectrum, that is, photons. — 00:00:00
  • ★★ Hank says that when Galileo first saw the moons of Jupiter he was looking at visible light photons. — 00:00:29
  • ★★ Hank says Jocelyn Bell Burnell's discovery of the rapid radio blinking of pulsars also came from telescopes detecting photons. — 00:00:29
  • ★★ Hank says much of the story of astronomy, and of how we understand the universe, has been expanding beyond visible light into other wavelengths. — 00:00:29

00:00:58 — Expanding into other wavelengths: JWST's infrared and the electromagnetic spectrum

  • ★★ Hank says a year after JWST's first photos, its strength is seeing further into the infrared, which requires being very cold because warm objects, including its mirror, emit infrared. — 00:00:58
  • ★★ Hank says the different kinds of electromagnetic radiation (infrared, ultraviolet, X-rays, gamma rays, microwaves) each give different clues about how the universe works. — 00:01:27

00:01:56 — Two new ways to observe: pulsar timing detects the gravitational wave background

  • ★★★ Hank says that in the last decade, especially the last couple of months, we gained two new ways to observe the universe, a huge deal, like Galileo first seeing Jupiter's moons twice. — 00:01:56
  • ★ Hank says the first new way, gravitational waves, got good press, which he was part of, talking about it a lot. — 00:01:56
  • ★★★ Hank says a powerful new method detects gravitational waves by timing distant pulsars in our galaxy, turning the whole galaxy into a giant gravitational wave detector. — 00:01:56
  • ★★ Hank says gravitational waves move things closer or further by about a meter per light year, detectable because pulsars flash so regularly. — 00:02:42
  • ★★★ Hank says pulsar timing has, for the first time, detected the gravitational wave background, which he calls extraordinarily cool. — 00:02:42

00:03:12 — Neutrinos, why they are hard to detect, and Antarctic ice as a natural detector

  • ★★ Hank says the second new way had a huge announcement the same weekend as the gravitational wave announcement and was a little overshadowed, which is a shame. — 00:03:12
  • ★★ Hank says events in the universe emit photons and also massive particles such as electrons, protons and nuclei, but those are absorbed by galactic gas and dust, so they are not very useful. — 00:03:12
  • ★★ Hank says a neutrino is like an electron but neutral, and that about 3% of the energy the Sun emits is emitted as neutrinos. — 00:03:38
  • ★★ Hank says about a hundred trillion neutrinos pass through each person every second. — 00:03:38
  • ★★ Hank says that because neutrinos are neutral and atoms are mostly empty space, nearly all neutrinos fly right through matter. — 00:03:38
  • ★★ Hank says detecting neutrinos has been a big deal in recent decades of science, earning several Nobel Prizes; when one hits a nucleus, light can be emitted or an element transformed. — 00:03:38
  • ★★ Hank says detecting many neutrinos would need a block of a substance kilometers on a side, more transparent than anything made in a lab, filled with light detectors. — 00:04:22
  • ★★★ Hank says deep Antarctic snow compressed over time becomes ice more transparent than anything we have, lying in darkness, so by chance Earth has the perfect neutrino detector. — 00:04:51

00:05:26 — IceCube, solar versus galactic neutrinos, and the first neutrino map of the galaxy via machine learning

  • ★★★ Hank says scientists drilled holes in the ice with hot water drills and lowered instruments to detect faint light flashes from neutrino collisions: the IceCube Neutrino Observatory. — 00:05:26
  • ★ Hank loves that the name IceCube stands for nothing because it is a big ice cube, though it is really more like a hexagonal prism. (playful) — 00:05:26
  • ★★ Hank says IceCube has detected over 100,000 neutrino collisions, a very small share of the neutrinos passing through it. — 00:05:55
  • ★★★ Hank says neutrinos from our galaxy would reveal things photons cannot, since dust clouds, the dark areas of the Milky Way, absorb light but not neutrinos. — 00:06:24
  • ★★ Hank says about 99.9% of detected neutrinos come from the Sun and must be separated from the far fewer coming from our galaxy. — 00:06:53
  • ★★★ Hank says machine learning made it possible to pick out galactic neutrinos and create the first map of our galaxy not based on photons, still very low resolution. — 00:06:53

00:07:23 — What neutrino astronomy could tell us; a remarkable time in science; sign-off

  • ★★ Hank predicts that as more collisions are detected, and hopefully detection improves, the neutrino map of the galaxy will get higher resolution. — 00:07:23
  • ★★★ Hank calls the IceCube observatory, a giant prism of ancient Antarctic ice, the most bizarre of telescopes, an entirely new way of observing our galaxy that will tell us much about how it works. — 00:07:23
  • ★★ Hank says neutrino observations, together with the gravitational wave background data, could help rewrite the laws of physics. (hedged) — 00:07:52
  • ★★ Hank says that unlike photons, neutrinos change: they can travel at different speeds and have different characteristics that reveal where they came from and what they experienced. — 00:07:52
  • ★★ Hank says it has been, and continues to be, a remarkable time in science. — 00:08:21

In the description and comments

  • ★★ The description calls IceCube a square kilometer of transparent ancient ice holding five thousand light detectors, and says it counts as a telescope. — video description

Threads in this video

Where the stories that moved here went next

Mentioned

Central: electromagnetic spectrum · IceCube Neutrino Observatory · neutrino

Also: People: Galileo Galilei · Jocelyn Bell Burnell

Organizations: Nobel Prize

Concepts: electron · gamma ray · gravitational wave · gravitational wave background · Infrared · machine learning · microwave · photon · proton · pulsar · ultraviolet · X-ray

Places: Antarctica · Jupiter · Milky Way · Solar System · Sun (star)

Products: James Webb Space Telescope

Only in the description or credits: Telescope

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