Astronomer, Harvard-Smithsonian Center for Astrophysics
In March, scientists working from the South Pole made a huge announcement. They had seen evidence supporting a key element of the Big Bang theory known as "inflation" — what's colloquially called the "bang" in the Big Bang.
Physicist and Harvard associate professor John Kovac is the leader of that team. He's been going down to the South Pole for over two decades. For the past several years he's served as principal investigator for the BICEP2 telescope, one of the latest instruments used to scan the sky for signals from the early universe.
The March results have since been called into question, with space dust potentially accounting for a large portion of what they believed to be gravitational waves. But even if only a small fraction of the signal they detected isn't dust, it's a stunning discovery.
We spoke with Kovac by phone in late November, using a patchy satellite connection to the South Pole. He's there setting up the next, even more powerful BICEP telescope.
How's the South Pole right now?
It's spectacular. It's just been beautiful weather down here the last two-three weeks since I got here. Clear blue skies and minus-40-degree temperatures. I'm sitting in a conference room right now at the Amundsen-Scott South Pole Station, which has been upgraded in the last decade. Beautiful new facility. So I've got this spectacular view out of the elevated station windows of the conference room.
"The exciting thing is those new datasets are coming very quickly now that we've achieved this breakthrough sensitivity."
What are you doing this year to set up BICEP3?
This year we have a team coming in that is preparing the BICEP observatory - we've had two previous telescopes, 1 and 2, of course - to hold a much larger machine, BICEP3, that has a focal plane five times as powerful as BICEP2.
It's coupled with another machine called the Keck Array, which has been operating at the South Pole for the past three years now, which is also five times as powerful as BICEP2. And the Keck Array has been operating at different frequencies. So the combination of BICEP3 and the Keck Array is going to be at least 10 times as powerful as BICEP2 was, and the data from the Keck Array is going to be coming out very soon, within the coming months. This is a fast-moving field. We're rapidly advancing the sensitivity.
How greatly does the improved sensitivity help your research?
That mapping speed is extremely important. BICEP2 was able to see the B-mode pattern [ed: a signal from the early universe] at high confidence, very high signal to noise, only in one frequency and only in one small part of the sky. So now, the key questions require us to follow up that pattern at multiple frequencies and over a larger fraction of the sky.
"We've only observed 2 percent of the sky so far"
You need a larger census population, if you will, to get good statistics on what the early universe was doing and so the only way to do that is to observe as much sky as you can. We've only observed 2 percent of the sky so far, so our plan is to expand that with BICEP3 and the Keck Array.
You'll be able to start doing that next year, when BICEP3 is ready?
We plan to start doing that in January with BICEP3. BICEP3 will be installed. We're starting right now. It should be commissioned in January and fully operational by February, we hope. It closes in mid-February. [The problem] with coming down here is that you get only three months every year to come and install and upgrade your new instruments and then you turn them over for nine months straight to the winter-over crew.
Of course, what everybody wants to know - us included - is when we're able to separate out the components with high confidence, what will be left over? Will the B-modes that BICEP2 saw so clearly be entirely explained by galactic dust or will there remain high-confidence evidence for a contribution from inflationary gravitational waves? That's the key science question that we're working on.
The goal is to continue investigating inflation, even if the results are less encouraging?
Whatever fraction of the signal that BICEP2 initially saw turns out to be attributable to dust, this is still an incredibly exciting field to pursue. We've reached breakthrough sensitivity, and we know now that our telescopes are capable of detecting signals that bear on incredibly fundamental physical questions. I suspect it will take multiple rounds of results to answer the question of what I was just speaking about, what fraction of the BICEP2 signal is down to galactic polarization and what fraction may be primordial gravitational waves.
The exciting thing is those new datasets are coming very quickly now that we've achieved this breakthrough sensitivity.
What is it that you find so interesting about investigating this subject? Why do you find it to be so critical to investigate inflation and these early portions of the Big Bang?
It seems to me there are hardly any bigger questions that we can ask as humans than, "How did our own universe start?" As a physicist, it's incredibly exciting to ask questions about the fundamental laws of our universe and specifically about how general relativity, which governs gravitational waves as we understand them, and quantum mechanics may have been united in the first fractions of a second of our universe to produce and explain the phenomena that we see in the universe today.
These are really big questions. The fact that we are able to build machines, relatively modest machines, that rely on very clever high technology that can be built by our own hands still, with small teams of scientists, and we can take these machines to the South Pole and make observations that can bear on these huge questions - we feel very fortunate to be able to do this.
Where do you see this research going next year or in five years or ten years? Do you have a clear picture of that?
Where it goes with respect to inflation is hard to predict at this point, and we will have to see where the data lead us. It could lead us in a direction where we are setting a large signal with a high enough confidence where we can really map out the inflationary process, or it could lead us in the direction where we are able to exclude a broad class of inflationary models and rule out that class of simple, large-field inflationary models, the models where inflation is happening at grand unified theory scales with high confidence.
Either one of those results would be pretty stunning. But the second result, of course, would still yield a wealth of information in the signals that we do observe because we're learning now better and better with every year how to turn these telescopes into fantastic, high-energy physics experiments.