Gravitational waves: have US scientists heard echoes of the big bang?

grauniad.co.uk

Reading that, I almost thought that Rupert Murdoch had bought the Guardian and staffed it with hacks from the long defunct News of the World!!!

A more balanced, sober report here from the good old BBC :-)

To be exact : 'good old Grauniad' is a quote from the character Jim Hacker of Yes Minister - an ancient TV series about British politics from the 70's/80's - the episode about the badgers and his daughter being a Trotskyte. They are probably better now with typos, but for a long while they were quite famous for evidently not reading their own articles, with the implication of what else might they not have paid attention to eg. truth & facts!! :-) :-)

In any case they were at least accidentally right on this occasion, so I must apologise .... ;-)

To the topic : this is deep result indeed, if confirmed elsewhere. 'B mode' refers to a mathematical pattern type, otherwise called the 'curl', that may be used to characterise vector fields. A vector field is where at every point in some space there is a vector defined, the idea being that this may point in different directions and have a different length depending upon which point you refer to. If it were water flow being modeled then a B mode would look like a whirlpool around a point. With respect to a given axis one can thus curl clockwise or anticlockwise. The other type is 'E mode', otherwise called the 'divergence'. For water this would represent a 'source' or a 'sink' depending on whether the nett flow was being emitted or converging respectively to a point. The 'B' and 'E' labels refer by analogy to the analysis of the electromagnetic vector field. B is for the magnetic component ( think of the magnetic field around a current carrying wire ) and E for the electric component ( think of the Coulomb force around a single charge ). These field characterisations are performed on a per-point basis and use mathematical gadgets like partial derivatives, dot and cross products of vectors, and trigonometry generally.

The upshot is that the density pattern on the CMB surface may be decomposed into a sum of B and E modes. The polarised light is used to map the density. B modes are the signal of gravitational wave activity. I'm very impressed that they spent an extra year re-checking their work for error before announcement. The 'r' value quoted is how much of the density map is accountable from gravitational wave propagation vs. some original ( quantum level ) imprint.

The underlying model implied/assumed here is 'inflation' where/when for the briefest of periods after singularity space expanded faster than the speed of light. Light still went at light speed though space. Hence what we see now - even out to the CMB surface - is but a tiny smidgen of a much vaster cosmos. As time proceeds then volumes of this larger, enclosing cosmos will come back into our horizon and thus be visible. These volumes were previously in causal contact with us prior to inflation. Back then the Universe was rather smaller than a gnat's private parts, thus subject to quantum mechanical fluctuations of energy/mass. Inflation 'froze' that quantum pattern in place.

Yeah, I have trouble with that construct too, but that's the description given.

[ As usual, the comment section below the SciAm linked article is replete with those who never emitted a prediction, but none the less claim post-hoc agreement with what they had in mind all along. But had kept a secret until now. Down at Flemington the bookies require placement of the bet prior to the race. I wunder why ?? :-) ]

Cheers, Mike.