Momentous Big Bang Findings Questioned

sciencehabit writes "The biggest discovery in cosmology in a decade could turn out to be an experimental artifact, according to a report by a physics blogger. The blogger says the BICEP group — the team behind the huge announcement of the moments after the Big Bang a few weeks back — had subtracted the wrong Planck measurement of foreground radiation in deriving its famous evidence for gravitational waves. As a result, the calculation is invalid and the so-called evidence inconclusive. Intriguingly, the BICEP team has yet to flat-out deny this."

Comments

Peer review

[meglon]

That's why we call it science, not religion.

Re:Peer review

[tloh]

Hold on there, Nellie. Aren't we being just a bit quick to point fingers? It is entirely appropriate to stand your ground if it is firmly rooted in solid evidence and good reason. Let the data be subjected to scrutiny and defend itself to the extent possible. More likely than not, it isn't as conclusive or accurate as some may hope, but it doesn't automatically make it bad science. Whatever short-coming is uncovered this time around is another stepping stone toward getting it right. No one is wrong simply because you or anyone else arbitrarily say so.

Re:Peer review

[AthanasiusKircher]

Why do you need that to prove the heliocentric model?

Because stellar parallax had been suggested as a necessary requirement for the heliocentric theory to be correct since the 1500s. Various attempts to measure it by Galileo's time had failed. So, the absence of parallax was one significant strike against heliocentrism in Galileo's day, if you go by evidence and scientific method. (Of course, the reality is that the "fixed stars" were much farther away than anyone thought possible, so it took much longer to measure the tiny movements necessary to show parallax.)

You just need to look at the planetary movement of one of the outer planets, like Mars. The outer planets appear to make a loop if watched from earth. The apparent retrograde motion could also be explained with deferent and epicycle but then you already left the geocentric model.

You should read some actual history of science, rather than the inaccurate executive summary version from some TV documentary.

In case you didn't know, Galileo's model of the solar system used perfect circles rather than ellipses (contrary to Kepler's elliptical model at the time, which actually fit the data -- Galileo frequently ignored inconvenient data when it didn't fit his astronomical theories). Thus, Galileo's model (and Copernicus's too) still required the whole Ptolemaic apparatus of epicycles. Contrary to popular belief, the circular heliocentric model that Galileo endorsed -- 'cause circles are cool and "perfect"! -- did not result in significantly easier math to explain the orbits.

Dig a little further into the controversy (for example, here or here, just to start with a few articles that are ~40 years old, showing how long historians of science have been pointing out significant problems), and you'll discover all sorts of other problems with Galileo's theories. For one, he originally wanted to publish his book as a theory of the tides -- because, frankly, that was the ONLY reason he had according to empirical science of the day that would differentiate a geocentric and heliocentric model. Of course -- well, the tides were caused by the moon, not the sun (again, Galileo thought Kepler's ideas that the moon caused the tides were stupid). But the bigger hole is that Galileo's theory required there to be only one high tide per day. As anyone who lived near the ocean at the time knew, there were two tides per day... but, well, that didn't fit with Galileo's theory. Oh well.

And, yeah, that was basically the only incontrovertible evidence Galileo put forward that proved heliocentrism over geocentrism (and note these were not just ignorant geocentrists: many of those in the Church at the time favored the Tyconic model, based on ideas from Kepler's teacher Tycho Brahe, who actually spent decades doing detailed empirical observations).

Seriously -- there were all sorts of valid objections to the earth's motion at the time when Newton's laws of motion weren't yet fully understood. Like why don't we fly off if the Earth is moving at such high speeds? Why don't we feel the motion? Why aren't there ridiculously high winds caused by rotation at high speed? Etc. We now know why these things don't happen, but actual scientists at the time weren't sure.

And Galileo's astronomical evidence really didn't amount to much (if he accepted Kepler's models, he might have something that fit the data better, but it still couldn't prove the motion of the Earth).

So, he hung his whole assertion of the proof of heliocentrism on the tidal theory -- which was so idiotic and so obviously contrary to observable evidence (one tide per day that has to come at noon?!?) that the censors refused to let him title his book "On the Tides" or whatever he wanted to call it, so he came up with the "Discourse on the Two World Systems" title.

Galileo was a great

Momentus? Really?

[Anonymous Coward]

It would be momentous if the editors actually did anything around here.

If it helps

[Anonymous Coward]

New Scientist, not a publication known choosing for sobriety over sensationalism but still at least a professional organisation who attempt to get quotes, have reported on this story.

http://www.newscientist.com/article/dn25558-rumours-swirl-over-credibility-of-big-bang-ripple-find.html

This article contains this couple of paragraphs:

" "The rumour is that the BICEP team has now admitted to the mistake," wrote Falkowski.

Kovac says no one has admitted anything. "We tried to do a careful job in the paper of addressing what public information there was, and also being upfront about the uncertainties. We are quite comfortable with the approach we have taken." "

What this means is that BICEP2 are happy that the approach they took should eliminate the foregrounds correctly. The challenge is that they misapplied a preliminary Planck foreground map, which presented foregrounds across a range of frequencies, as applying only to a single frequency. If they actually did this then the BICEP2 analysis will certainly have to be redone, but there's no way Kovac is going to comment on that while work is going on behind -- it would be breach of contract if nothing else. If BICEP2 have done it and it comes out either in their own further release (most likely dropping the detection of gravitational waves down to a constraint of r~0.15 or so, which would still be good results) or ultimately in Planck's own polarisation release, then they'll explain what's gone wrong, or have it explained for them. Of course, it will be less embarrassing if they release their own partial retraction and explain their own mistake, rather than having others do it for them.

Ultimately, what we can say is that the BICEP2 dataset is valuable and, at present, nigh-on unique. It won't stay so for very long given the number of experiments that also target CMB polarisation which are upcoming, but we will never sneer at a further dataset -- and whether or not they've made a mistake in their analysis it's not as though the team were composed of chumps; this is a high-quality team, who have produced high quality data, which can be combined with other datasets to ultimately yield far tighter bounds on a variety of cosmological parameters. Any kind of witch-hunt should be ignored as the media-driven infantilisation it will doubtless be.

(Also while I agree with a couple of other posters that science by blog is pretty nauseating, it's ultimately no different from its previous incarnation, science by conference coffee break - just more pervasive. I still really don't like it but it's a fairly natural progression.)