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Swirls In the Afterglow of the Big Bang Could Set Stage For Major Discovery
sciencehabit writes "Scientists have spotted swirling patterns in the radiation lingering from the big bang, the so-called cosmic microwave background. The observation itself isn't Earth-shaking, as researchers know that these particular swirls or 'B-modes' originated in conventional astrophysics, but the result suggests that scientists are closing in on a much bigger prize: B-modes spawned by gravity waves that rippled through the infant universe. That observation would give them a direct peek into the cosmos' first fraction of a second and possibly shed light on how it all began."
Short story swirls** have nothing to do with strings, nor dimensions, just vanilla big-bang stuff...
Let's start with what this is.
Basically, cosmic microwave background radiation (aka CMB) is theorized to be weakly linearly polarized due to scattering processes like Thomson Scattering with free-electrons. Since this polarization has 2 net degrees of freedom, you can measure it a few different ways, but one interesting way to do so is to use divergence component (aka E-mode), and curl (aka B-mode) which comes from an analogy with electromagenetics*** So far they've measured some linear polarization with an E-mode component (since it has divergence only, you can think of as being scattered from the position of the last object/electron it interacted with shortly after the big-bang), but until now they've not confident that they measured any net B-mode component in CMB radiation.
E-mode polarization measurements in conjunction with theories about the CMB temperature has helped to advance some theory about some cosmological constants. B-mode measurements are interesting in that if detected are likely from stochastic scattering of a radiation field which is theorized to come from some sort of gravitational waves generated when the early universe was undergoing inflation, but unfortunatly since this is a scattering effect, it could also originate as E-mode and later converted to B-mode by gravitational interaction with matter since the big-bang (a kind of gravitational lensing effect). So B-mode is really small and noisy (which is why they had a hard time isolating it), but it might help us understand if the inflation model is consistent with the universe we see.
**Somehow "curl" gets converted "swirls" in laymanspeak...
***static electric fields (aka 'E' fields) exhibit net divergence from electrical "charges", but static magnetic (aka 'B'**** fields) don't have this because there aren't magnetic monopoles, so they only exhibit net curl (kind of a rotation), but this scattering polarization "mode" really doesn't have too much to do with this (since even polarized electromagnetic radiation has both E-field and B-field components), except for the general mathematical concepts of div and curl.
****Apparently, Maxwell used the letter 'B' (and 'H') to represent magnetic fields when he wrote his Maxell's equations and it stuck. Today, 'M' is commonly used for magnetization (maxwell apparently used 'I' for magnetization and 'C' for current, but now we use 'I' for current so go figure some terminology doesn't stick).