“Every philosophy also conceals a philosophy; every opinion is also a hideout, every word also a mask.” -Friedrich Nietzsche
If you want to see all the way back to the Big Bang — to the cosmic microwave background — that means looking back through billions of light years worth of space. While individual point sources like stars and distant galaxies are relatively easy to exclude, the most catastrophic interfering factor is the Milky Way itself. Gas, dust, spinning molecules, magnetic fields, stars and more are all known to play a role.
But a couple of large mysteries ensued when we looked at the neutral hydrogen within our own galaxy: the neutral hydrogen was aligned with the galactic magnetic field, and is also associated with the polarization of the CMB. But neither of those sources should affect neutral hydrogen. What’s going on?