Science Interviews


Fri, 26th Sep 2014

Big Bang dustup

Graihagh Jackson, Naked Scientist

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In March this year, the US BICEP team of astronomers claimed to have found the The first stars in the Universe turn on at about 400 million years after the Big Bang.long-sought evidence for cosmic inflation - one of the mechanisms that underpin what happened in a fraction of a second after the Big Bang when the Universe began. Inflation has been theorised for decades and the results caused a big  stir in the scientific community, with talk of Nobel prizes being awarded to the American astronomers. But, just this week, these findings have been called into question, as Europeís Planck satellite published data suggesting the BICEP results could have been caused by cosmic dust contamination. Graihagh Jackson has been looking at this story and told Chris Smith the latestdevelopments...

Chris - So, whatís first of all the background to this?

Graihagh - As you mentioned already, inflation was a theory developed in the 80s to help explain what happened in the first trillionth of a trillionth of a trillionth of a second after the Big Bang, and what happened in inflation is that space expanded very, very fast, faster than the speed of light from something the size of a proton, so, smaller than an atom, all the way to what we now see as the observable universe and this happened all in the fraction of a second. So, according to this theory, the expansion would have caused a sort of ripple in space and time, waves of gravity, and these waves and ripples have left like a pattern on the sky, so to speak, that we could potentially now see and this is what BICEP have claimed to have seen. This polarised cosmic micro background radiation or CMB.

Chris - So, if these waves are there, then it lends credence to the theory of inflation. It tells us what must have happened in the early epoch of the universe during those very, very early times when it was growing rapidly.

Graihagh - Precisely, yeah. It puts us that much closer to seeing the origins of our universe and how it came to be, and Iíve heard about physicists talking about this could be, you know, discovery of their lifetime sort of thing. So, itís caused a really big stir in the scientific community.

Chris - A ripple even.

Graihagh - A ripple. Yes, precisely!

Chris - Itís not just in space-time. And what has Planck now done, because to put this into perspective, Planck is a satellite mission that launched from the European Space Agency 2009, I think it was, wasnít it, to try and probe some of these and other questions. So, what is the Planck probe saying?

Graihagh - Itís worth just stepping back a little bit here and talking about what BICEP did. So, BICEP looks at a very small sections of sky and is looking at one frequency or color and thatís what they were monitoring in the sky, whereas Planck looks at a huge area in the sky and is looking at multiple frequencies, and these frequencies that the Planck is looking at are much more sensitive to things like cosmic dust, the dust in the sky from asteroids, comets, and when stars explode. So, what Planck have now done is theyíve looked at exactly the same area of sky that BICEP have looked at and they now think that actually, thereís much more dust than they previously thought, and this dust is imitating the polarised CMB.

Chris - The shortfall of the BICEP mission - we actually had them on this program at the beginning of the year when they made this announcement - was that they looked at just this one discreet frequency because we asked them why didnít you look at others, and they said, well our instrumentís set up to look at that particular color of light. Planck now say, theyíve looked at other colors, youíre saying, and that actually you may be able to explain those initial observations on the basis of dust. So, what do the BICEP people say about it?

Graihagh - BICEP have always been wanting to corroborate these results. Itís just only that now that the Planck satellites come available to actually look at this segment of the sky. So, they havenít commented on it, so to speak, itís always been in the pipeline that theyíre going to come together and look at results together to see whether actually it is this sort of cosmic dust thatís causing this, this signature in the sky or whether actually we really are seeing a signature of the beginning of our universe.

Chris - Ironic, that the guys who discovered the Cosmic Microwave Background radiation, and it won them a Nobel prize in the 1960s, this is Wilson and Penzias. And they actually first of all thought that pigeon poo on their antenna was the cause of this funny signal they were seeing, and it turned out that was the after-glow of the Big Bang. Now these guys might actually done the reverse and claimed to have seen something that is caused by the space equivalent of pigeon poo, cosmic dust. So what does this actually mean then, in real time terms? Are they now saying we're going to go and do some more studies or what?

Graihagh - So the Planck people and BICEP people are now coming together to look at results because as I said before theyíre quite different data sets, apples and oranges if you like, so theyíre now looking to put these results together, see what the results are, and we should actually see something coming out at the end of the year. Whether really, it was dust or whether we are seeing the beginning of our universe.

Chris - So there may still be a Nobel prize up for grabs. Graihagh, thank you very much. Graihagh Jackson. And Planckís data that Graihagh was describing was published just this Monday in the online journal Archive.


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