Let
me explain exactly why a new scientific paper by the Planck team
throws grave doubt on the BICEP2 study, by making it seem rather
likely that the “epic discovery” may be merely the observation of
ordinary, run-of-the-mill dust. I will use scientific visuals rather than rumors.
First let us look at a graph from a scientific paper by another scientific team (POLARBEAR) that is doing studies very similar to the BICEP2 study. It is a graph with the same scale and legends as the key graph of the BICEP2 paper. The graph is below.
First let us look at a graph from a scientific paper by another scientific team (POLARBEAR) that is doing studies very similar to the BICEP2 study. It is a graph with the same scale and legends as the key graph of the BICEP2 paper. The graph is below.
Graph
1, from the POLARBEAR scientific paper
The
graph above shows some purple lines. The lower dark-dashed purple
line shows b-mode polarization observations we would expect to see
from galactic dust, if a parameter called the polarization fraction
(represented by the letter p) is equal to 1.5%. The higher
light-dashed purple line shows b-mode polarization observations we
might expect to see from galactic dust, if a parameter called the
polarization fraction (represented by the letter p) is equal to 10%.
Below
is the key graph from the BICEP2 paper. Notice that this diagram and
the first diagram are plotting the same thing on the same scale (the only difference being that the POLARBEAR graph goes down slightly lower on the scale).
Graph
2, from the BICEP2 scientific paper
Because
these two graphs plot the same thing on the same scale, it is very
easy to take the 10% dust polarization line from the first graph and
move it to the second graph. When we do that, we get the following
graph:
Graph
3, combining the BICEP2 graph with one line from the POLARBEAR graph
This
graph should be very worrying for anyone who thinks that the BICEP2
observations are from the Big Bang or cosmic inflation. The graph
shows that if there was dust polarization of about 10%, then that
could explain the BICEP2 observations (as the purple line in the
graph above cuts right through the black dots representing the BICEP2
observations). I don't have a graph showing 13% dust polarization,
but that would be a purple line higher than the purple line above,
and in such a case all of the BICEP2 observations could be explained
from a combination of dust polarization and gravitational lensing,
shown by the solid red line in the graph.
So
the key issue is: how high is this dust polarization fraction? If
it's only 1.5% then the BICEP2 team has little to worry about, but if
it's 10% or 15% then all the BICEP2 observations can be explained by
ordinary dust and gravitational lensing, and the claims of an “epic
Big Bang breakthrough” would seem to crumble completely.
In
the BICEP2 paper the scientists refer to a preliminary pdf which they apparently used in estimating the polarization fraction, a PDF with the following visual showing dust polarization fractions in various regions of the sky:
Graph
4, preliminary Planck map used by BICEP2
Notice
the legend at the bottom that indicates the dust polarization
fraction, which extends from 0% (deep blue) to 20% (red). The BICEP2 observations were from a region around the
bottom middle of this map. Based on the map above, you might have
estimated that there was a dust polarization fraction between about
5% and 7%. That would translate to a purple line uncomfortably close
to the 10% line in my combined graph above (graph 3), but it would still leave
a little breathing room.
However,
in the past two weeks the Planck team has published a scientific paper that includes a revised version
of the graph above. The graph (which excludes certain areas) is shown
below:
Graph
5, the later Planck map published in a scientific paper
Such
a result casts very grave doubt on the pretentious cosmic claims of
the BICEP2 team. If the dust polarization is greater than 10% in the
area observed by BICEP2, it means the dust polarization line is even
higher than the purple line I have drawn for graph 3. In such a case
all the BICEP2 observations can be explained by ordinary dust and
gravitational lensing, not something special that happened in the Big
Bang.
It
will be quite an irony if this turns out to be true. The scientists
who thought they were seeing something extraordinarily special (an
echo from the first second of the universe's creation) may really
just have detected polarization from something as ordinary and common
and lowly as the dust on your shoes.
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