"Could". And then the first thing in the article is an ass covering link to the opposite:
http://www.theguardian.com/science/acro ... ilae-comet
Anyway I forgot to thank i$ for the video. Watched it in hospital. Terrible microphone technique! But apart from that, so informative. If only we had better media that could handle communicating complex stuff like this. Case in point: that headline above!