Fritz Zwicky - Blog Posts

Ep. 14 Dark Matter Part 1 - HD and the Void

In preparation for a future interview with someone who knows much more about astroparticle physics and dark matter than I do, tune in this week for a quick-and-dirty breakdown of a theoretical particle that, if it exists, would clarify a couple of...

We’re getting theoretical here, and not just astronomy theory but particle theory. That’s right, it’s a dark matter podcast! Learn what some astronomers think it is and why other astronomers think there are better explanations for certain nutty galactic phenomena. Hear about MACHOs and WIMPs! Also learn what dark matter is too hot, too cold, too medium, or just right! 

Below the cut are my sources, music credits, a vocab list, a timeline of the scientists I mention, and the transcript of this episode. Tell me what you think I should research next by messaging me here, tweeting at me at @HDandtheVoid, or asking me to my face if you know me in real life. And please subscribe to the podcast on iTunes, rate it and maybe review it, and tell friends if you think they’d like to listen!

(There’s a lot of ever-evolving info about dark matter and I was not able to cover all of it in just one episode, so get excited to hear about dark matter’s friend, dark energy, on November 6th. My thoughts on the episode after that are still the Voyager golden records, space race history, the transit of Venus, the Moon landing, or Edmond Halley. Let me know what you think!)

Glossary

astroparticle physics - the interface between astrophysics and particle physics.

baryons - heaviest particles. Ex. Protons, neutrons. In astroparticle physics, electrons are included in baryonic matter.

bosons - particles that can exist in the same state at the same location at the same time. Ex. Photons, Higgs boson.

cosmic microwave background radiation - the electromagnetic radiation left over from the time of recombination in Big Bang cosmology.

dark matter - a theoretical mass made up of unknown particles that have not been created on Earth. It is used to explain why galaxy clusters have 10x the mass that their light output suggests they would have; why distant stars on the edges of spiral galaxies orbit at the same speed as stars near the center of the galaxy; and the accretion of gases that created galaxies at the beginning of the universe.

fermions - particles that cannot exist in the same state at the same location at the same time. Ex. Protons, neutrons, electrons, leptons.

gravitational lensing - when light from more distant sources passes near a massive star, galaxy, or galaxy cluster and the object’s gravity bends the light like a lens to provide a warped angle view of space.

leptons - lightest particles. Ex. Electrons, neutrinos, tau particles, muons.

MACHO - acronym for MAssive Compact Halo Object. Made of baryonic matter, these objects are a theoretical explanation that takes the place of dark matter and include neutron stars, black holes, or brown dwarfs.

mesons - medium-weight particles. Ex. Pions, kaons.

Planck satellite - a spacecraft that operated from 2009 to 2012. It measured the dark matter content of the universe by looking at the cosmic microwave background radiation and seeing how dark matter clumped and drew the regular matter together to form galaxies.

WIMP - acronym for Weakly Interacting Massive Particle. Theoretical particles that can pass through ordinary matter without affecting it.

Wilkinson Microwave Anisotropy Probe - a spacecraft operating from 2001 to 2010 which measured temperature differences in the cosmic microwave background radiation leftover from the Big Bang.

Transcript

Sources

Fritz Zwicky via the Swedish Morphological Society

Fritz Zwicky via the American Museum of Natural History

Zwicky: “Astronomers are spherical bastards. No matter how you look at them they are just bastards“

Vera Rubin via the American Museum of Natural History

Vera Rubin via Astronomy Magazine

Morton Roberts’ 2007 article on dark matter via Harvard

Particle classifications via PhysicsNet.co.uk

Leptons via Georgia State University, copyright 2001 and all written by Carl “Rod” Nave, who has a teaching award named after him at GSU. Go Rod!

Fermions and bosons via The Particle Adventure

MOND theory by Mordehai Milgrom, published in Scientific American Aug. 2002

Newton’s Second Law of Motion via NASA

MACHOs and WIMPs via NASA

MACHOs and WIMPs via the Encyclopedia of Astronomy and Astrophysics

Bertone, Gianfranco. Behind the Scenes of the Universe: From the Higgs to Dark Matter. Oxford U P: Oxford, 2013.

Tucker, Wallace H. Chandra’s Cosmos: Dark Matter, Black Holes, and Other Wonders Revealed by NASA’s Premier X-Ray Observatory. Smithsonian Books: Washington, D.C, 2017.

“a mysterious force that causes the observed accelerating expansion of the universe” (3).

“sterile neutrinos, axions, asymmetric dark matter, mirror dark matters, and extradimensional dark matter” (23).

“the concentration of dark matter is leveling off, rather than peaking sharply, in the central regions of this cluster” (31).

Timeline

Albert Einstein, German/Austrian (1879-1955)

Edwin Hubble, American (1889-1953)

Walter Baade, German (1893-1960)

Fritz Zwicky, Swiss (1898-1974)

Enrico Fermi, Italian (1901-1954)

Morton S. Roberts, American (1926- )

Vera Rubin, American (1928-2016)

Peter Higgs, English (1929- )

Kent Ford, American (1931- )

Mordehai Milgrom, Israeli (1946- )

Romeel Dave

Rachel Somerville

Intro Music: ‘Better Times Will Come’ by No Luck Club off their album Prosperity

Filler Music: ‘Darkmatter’ by Andrew Bird off his album Fingerlings 3

Outro Music: ‘Fields of Russia’ by Mutefish off their album On Draught