February 3 – Flexing Our BICEP2

Today’s factismal: When one scientist makes a goof, another one catches it.

If you watch a typical movie or TV show with scientists in it, you’ll come away with one of two views of how we do science. Either we are mad geniuses, toiling alone in laboratories until we accidentally set the cat on fire and run out of the room screaming “There are somethings that man is not meant to know!” or we are mindless drones who all agree that thus and so is the right idea and anyone who disagrees (who typically turns out to be the mad genius previously described) is an idiot. And, of course, neither version is true. Heck, neither version is even close to being true.

The Cosmic Microwave Background that proved the existence of the Big Bang (Image courtesy NASA / WMAP Science Team)

The Cosmic Microwave Background that proved the existence of the Big Bang
(Image courtesy NASA / WMAP Science Team)

If you’d like a view of how real science is actually done, then you need look no further than the BICEP2 experiment. But in order to understand the experiment, you need to go way, way, way back in history. About 13.8 billion years back, to be specific. At that point in time, the universe was also a point in space – literally! All of the matter that would become the stars, planets, and us was compressed into a volume so small that you could have fit a billion universes inside an atom.  And then, just a moment later, the Big Bang happened. Suddenly, all of existence rushed out and within 10−32 seconds (about as long as it takes a politician to break a promise),the Universe had spread into a volume some 65 billion light years across. Since then, the Universe has only grown to 93 billion light years across. And that puzzles scientists. How could the Universe get so big, so fast?

To understand that, we have to look at the leftover light from the Big Bang, known as the Cosmic Microwave Background (CMB to all the astronomy wonks out there). Because the Universe didn’t expand uniformly, there were tiny ripples left in the CMB. By looking at those ripples, we hope to learn more about conditions in the early Universe. And that’s what BICEP2 (Background Imaging of Cosmic Extragalactic Polarization, Round 2) team did. They used telescopes hung from balloons in Antarctica to image the CMB and made an amazing discovery: the light was strongly polarized! That meant that we had evidence of how that early inflation happened. Astronomers were thrilled and the public was confused.

A composit image from POLARBEAR showing the presence of dust (Image courtesy ESA)

A composite image from the Plank satellite showing the presence of dust
(Image courtesy ESA)

But then another group of scientists running a rival experiment known as POLARBEAR took a look at BICEP2’s data and said “not so fast! That could just be dust blowing in the cosmic wind!” They claimed that the scattered signal from dust would look a lot like the real signal that BICEP2 thought they’d detected. BICEP2 grumbled and groaned and finally admitted that POLARBEAR had a point and that they should all wait for more data before deciding. This week, the Europeans Space Agency announced results from the Plank satellite; the signal seen by BICEP2 was really noise caused by dust and the inflation of the Universe took place even earlier than we had thought. So now the two groups are arguing over how much earlier and how it happened. And that’s what happens a lot in science: one scientist or group of scientists looks at data, gets excited, and makes a mistaken claim then another scientist or group of scientists comes in and re-evaluates the claim. When that happens, you know that there is real science (as opposed to movie science) being done.

Now if you’d like to do some real science, why not join the folks at the Lowell Observatory for the Lowell Amateur Research Initiative (a.k.a. LARI – I swear, these scientists and their acronyms!)? LARI has several experiments that you can take part in, ranging from looking at dwarf galaxies to finding new planets to identifying old instruments. And if you make a mistake, don’t worry – it just proves that you are a real scientist!

One thought on “February 3 – Flexing Our BICEP2

  1. Pingback: October 22 – The Narrative of Arthur Gordon Pym of Nantucket | Little facts about science

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