Everyone wants to be right. Most of us sure hate being wrong.
But scientists know that new discoveries often change or even invalidate earlier ideas. Being wrong can mean we have learned something new.
This week, a controversy about the Big Bang and the origin of the universe came to light at the American Astronomical Society conference in Boston. In an invited lecture sponsored by the Kavli Foundation, Princeton astrophysicist David Spergel offered a different idea about a discovery made last March, where the BICEP2 Antarctic cosmology experiment reported evidence of a period of rapid "inflation" in the very early universe. Specifically, researchers detected the special pattern of polarization that would be caused by gravitational waves stretching and squeezing space itself during inflation.
Last week, three theorists - Alan Guth, Andrei Linde and Alexei Starobinsky - were awarded the prestigious Kavli Prize for astrophysics for their work developing the theory of cosmic inflation. (This prize and the AAS lecture were sponsored by the same foundation but were otherwise completely independent.) Their award may well have been prompted by the BICEP2 discovery, which generated a lot of excitement about early universe cosmology.
But at the American Astronomical Society conference, Spergel argued that the BICEP2 results reported in March could instead be explained by a more pedestrian effect, namely, light scattering off dust between the stars in our Milky Way galaxy. If he is correct, the widely heralded BICEP2 announcement was premature at best and wrong at worst.
This kind of controversy is completely normal in science. It's the way science progresses. You put an idea out there and your colleagues - many of them good friends and scientific collaborators - try to shoot it down.
A scientist's first reaction to a new idea is often: "That's wrong because." To which the proponent replies, "No, you are wrong because..." And so the debate begins.
No matter how much a scientist might hope to be right, nature holds the answer. One theory may be more beautiful than another, or more complicated, or more elegant, but nature doesn't know or care. The job of a scientist is to find out what the real answer is, not to advocate for any one point of view.
We do that by making careful measurements and assessing the accuracy of the result. BICEP2 detected certain polarization patterns in light from the cosmic microwave background, which they believe were created during inflation. David Spergel is instead suggesting the light was polarized by passing through galactic dust near the end of its journey to our telescopes - indeed, he argued, this dust is expected to create the kind of polarization signal BICEP2 saw.