We asked this question of Clare Bryant, a biologist who now works in a multidisciplinary team working with lasers...

Clare -   It was quite interesting, actually. I started doing some work with a colleague of mine called Julia Gog in the Maths Department and we had a few beers one evening and we were chatting about the sort of basic principles that were involved in how Salmonella infect cells.  She asked me a lot of really awkward questions and I was sitting and thinking, “Well, do I know the answers? - Well I think I do".  I went away and looked in the literature and in fact, not many of the answers were actually known.

So we started to talk about this and then we started to collaborate with a physicist called Pietro Cicuta and when we had our experimental questions, Julia would say, “What about this?”  And I say, “Well I think it does that, but I can't quite build the kit to do it so I don't quite know how to do this.”  Pietro said, “It’s all right.  I can build a piece of gear!”

So we started the three-way collaboration with awkward questions.  My ideas for biological experiments and Pietro then saying, “Yeah, we can do this.  We can do this this way, that way or the other.”  It’s then proven to be just really, really exciting to do experiments.  I never dreamed it possible, to be honest.

Ben -   So, this is how the real novel stuff comes about, isn’t it? It’s when researchers from different fields get together, maybe over a beer, maybe for coffee perhaps, and this fantastic fabulous research comes out.

Clare -   Yeah.  It’s just amazing to me.  I hadn’t been sure how multidisciplinary work would really happen and having had this kind of interaction with these guys, I'm now trying to learn their language.  Obviously, the mathematical language is very, very different from the biological language, and they (Julia and Pietro) are embryo biologists, but the kind of interaction between the three of us is just proving to me to be a real eye-opener and an obvious way forward for us.

We've answered this question before - here and here...

Ben::  What the theory suggests is that if you were to drop a marble or jump down this hole, you would accelerate as you get towards the centre of the Earth, and then when you pass the centre of the Earth, you'd start to decelerate [accellerate in the opposite direction - for physics pedants].  But because of the energy you'd built up, you would in fact go all the way through to the other side. 

Now, if you're lucky and had something to grab hold off then you could get out on the other side, but if not, then the same thing would happen again.  You would turn back and you'd oscillate one way then the other and just bounce around between sides of the Earth. 

The theory is it should take around the same amount of time that it takes to orbit the Earth, so somewhere around 45 minutes from one side to the other.

You might notice from our previous answers that this assumes the tunnel to be evacuated of air - as the air pressure at the core would be incredible, and you would experience very high drag - a marble would be fine, but could you hold your breath for 45 mins?

Helen -   I don't have a touch screen.  I've got an old fashioned one with buttons, but I imagine the same thing would count with buttons as well as touch screen.

Ben -   I think it probably would.

Helen -   I suppose it all comes down to how well you wash your hands after you've been to the bathroom – what kinds of bacteria that pass through our systems end up on our hands and on our phone.  Will they survive and live on our phones?  That’s the question I suppose.  Would they be able to actually form colonies?

Ben -   Well bacteria can survive quite a long time actually on various surfaces and we know of around about 1,000 different bacteria species that will live on our skin.  I think you probably could tell the key areas that are touched most because you're going to put down more grease on there, you're going to put more skin cells which will act as food, and you're going to put more bacteria on there, so yes, possibly.  It could be a very good way to find out what buttons people press most often which is really quite disturbing when you think about it that way...

Ben -   I regret that Dave Ansell isn’t here because he would give us a wonderful and distinctive answer in his very individual style, but I'm going to give it a go.

I'm not a physicist, but what I think happens is you get an equilibrium between molecules of water that are frozen in the ice and molecules in the water, and they will move back and forwards.  So constantly, you get these molecules that are becoming water or forming back into the ice structure. 

This equilibrium is temperature dependent.  So, when it’s above a certain temperature, more of these molecules are going to come out of the ice structure and into the water structure, and this means in total, you'll get less ice, more water, and eventually, the ice cube will melt.

Now of course, the interesting thing is looking at the fact that because of the density of ice, if you put an ice cube in a very full glass of water, so much of it is floating above the surface that when it melts, your glass of water still won't overspill.

Helen -   It’s actually a really important question as well, not just through ice in our glasses, but ice in the sea and why that doesn’t melt or when it does melt, and how that will cause or won't cause changes in sea level as well.  So I think that’s a really, really big question from what sounds like something that’s just about having a nice cool drink on a hot day.  Actually, it’s got really big implications for all sorts of things going on in the natural world.