Roy from Spalding asked:
American engineers have just developed a camera which by what I've seen on television actually slows light down. I was wondering if you could tell me what it's going to be used for.
Dave - Okay, so the way that camera works Ė I saw this story a while ago Ė itís an actually incredible and I think itís brilliant is that essentially, it actually can only take one line of the picture. So, a picture is made of lots of different lines. It can only take one line of a picture in each burst of light. Basically, they send out lots and lots of bursts of light very, very quickly and they built up lots and lots of lines. And you take them exactly the same position of where the burst of light is, so you can build up the video that youíve seen.
The way they want to use it is because the really neat thing is if you can actually see light as itís traveling is that you can sort of use it a bit like radar on a really small scale. So, you can actually bounce it off just a normal wall and the light will bounce off the wall and then bounce around the room which you can't actually see and then bounce back again. If you can see exactly when all that light gets to you then if you can put that through a big computer you can actually work out what's around the corner. So, you can actually see around a completely normal corner with no mirror at all, just by being able to see the light as it comes back 1 nanosecond at a time.
Dominic - So, what you're saying is if you see a pulse of light arrive at a certain time, you know that light must have travelled a certain distance. You know, the spped of light, so you know something in that room round that corner bounced that light back at such and such time. So, it must be such and such distance away.
Dave - And youíve got some idea where itís coming from, so you can take all this information put it together and build a model of a room.
Ginny - Would you be able to tell what was in the room or would you just know that there was something?
Dave - Pictures I've seen ... it's quite early daysÖ
Chris - Itís amazing isn't it...
Dave - Yeah, they've actually built up a rough shape of an object and you can get some idea of the colour as well. If youíve got a colour camera, you can tell what colour the light was which got there.
Chris - It was one of those mannequins, those artistís wooden mannequins, you know, the ones you put into funny postures and they had one of those. The pictures that it rendered afterwards were absolutely stunning. You could tell without a shadow of a doubt what it was, couldnít you?
Dave - Yeah.
No camera can slow down the speed of light in a vacuum so since it's not in a vacuum what is it in? Pmb, Tue, 10th Sep 2013