CMB Part 2: The “Smoking Gun” of the Big Bang

Ethan Siegel
Nov 4, 2014 · 9 min read
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Image credit: Hans Fuchs, of the electric and magnetic fields in a photon oscillating, via http://wiki.awf.forst.uni-goettingen.de/wiki/index.php/Electromagnetic_radiation.
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Image credit: ESA and the Planck Collaboration.
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Image credit: NASA / WMAP science team.
  1. electrons are accelerated into motion when they’re under the influence of an electric field, and
  2. as electrons accelerate, they emit photons most often at a 90 degree angle to the direction they’re moving.
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Image credit: Wikimedia Commons user AllenMcC.
  • Because the electron is accelerating, it emits a new photon.
  • Quadrupole patterns seen by an electron (hot spots above and below and cold spots to right and left, for example) accelerate the electron in such a way that the re-emitted photons are polarized.
  • And finally, Quadrupoles seen by an electron are the only patterns that lead to observable polarization in the CMB.
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The image shows how a ring of particles (black dots) is deformed as a gravitational wave passes through. In the CMB, the stretching causes photons to look colder and the contracting causes the photons to look hotter, setting up a quadrupole for producing polarization. Images credit: Wikimedia Commons user MOBle.
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Image credit: John Kovac, via http://cosmo2014.uchicago.edu/depot/invited-talk-kovac-john.pdf.
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Images credit: NASA/WMAP.


Starts With A Bang!

The Universe is out there, waiting for you to discover it.

Ethan Siegel

Written by

The Universe is: Expanding, cooling, and dark. It starts with a bang! #Cosmology Science writer, astrophysicist, science communicator & NASA columnist.

Starts With A Bang!

The Universe is out there, waiting for you to discover it.

Ethan Siegel

Written by

The Universe is: Expanding, cooling, and dark. It starts with a bang! #Cosmology Science writer, astrophysicist, science communicator & NASA columnist.

Starts With A Bang!

The Universe is out there, waiting for you to discover it.

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