It's interesting that some people find Science so easy and others find it kind of dull and difficult - especially kids; some of them just eat it up. And I don't know why it is. It's the same perhaps for all subjects, for instance lots of people love music and I could never could carry a tune. I lose a great deal of pleasure out of that, and I think people lose a lot of pleasure who find science dull.

In the case of science I think that one of the things that make it very difficult is it takes a lot of imagination. It's very hard to imagine all the crazy things that things really are like.

Nothing is really as it seems - we're used to getting hot and cold, and all that hot and cold is is the speed at which the atoms are jiggling. if they jiggle more it corresponds to hotter, and colder is jiggling less. So if you have a cup of coffee sitting on a table and the atoms are jiggling a great deal in the coffee and they bounce against the cup, and the cup then gets shaky, and the atoms in the cup shake and they bounce against the saucer and the heat heats the cup and it heats everything else. That hot thing spreads its heat into other things by mere contact because the atoms that are jiggling a lot in the hot thing shake the ones that are jiggling only a little bit in the cold thing, so that the hot heat we say goes into the cold thing - it spreads. But what's spreading is just jiggle and irregular motions, which is easy to understand.

It brings up another thing that's kind of curious - I say the things jiggle and if you're used to balls bouncing you know that they slow up and stop after a while. But we have to imagine with the atom a perfect elacticity - they never lose any energy. Every time they bounce they keep on bouncing all the time; they don't lose anything - they're perpetually moving. And the things that happen when we say something loses energy - if a ball comes down and bounces it shakes irregularly some of the atoms in the floor, and then when it comes up again it leaves some of those atoms moving, or jiggling. So as it bounces it's passing its extra energies - its extra motions - to little patches on the floor each time it bounces and loses a little each time, until it settles down - we say, as if all the motions stop. But what's left is the floor is shaking more than it was before, and the atoms in the ball are shaking more than they were before. That the organized motion of all these atoms moving the same way falling down, and the quiet floor, is now transformed into a ball sitting on the ground - but all that motion is still there in a form - all the energy of motion - in the form of the jiggling of the floor which is a little bit warmer. Well how unbelievable? But anybody who's hammered a great deal on something knows that it's true - that if you pound something - hit it a lot - you can feel the temperature difference; it heats up. It heats up simply because you're jiggling it.

This picture of atoms is a beautiful one, and you can keep looking at all kinds of things this way. You see a little drop of water - a tiny drop - and the atoms attract each other, they like to be next to each other, they want as many partners as they can get. Now the guys that are at the surface have only partners on one side with the air on the other side, so they're trying to get in. And you can imagine this teem of people - these teeming people - all moving very fast, all trying to get, to have, as many partners as possible. And the guys at the edge are very unhappy and nervous and they keep pounding in, trying to get in, and that makes it a tight ball instead of flat, and that's, you know surface tension the way when you realize you know how a water drop sits like this on a table and then you start to imagine why it sits like that - because everyone is trying to get into the water. And at the same time while all of this is happening there are these atoms that are leaving the surface and the water drop is slowly disappearing.

I find myself trying to imagine all kinds of things all the time, and I get a kick out of it just like a runner gets a kick out of sweating, I get a kick out of thinking about these things. I can't stop, I mean I could talk forever. You cooled off the water so the jiggling is less and less and slower and slower and then the atoms get stuck in place - they like to be with their friends; the force of attraction. And then they get packed together; they're not rolling over one another, they're in a nice pattern like oranges in a crate, in a nice organized pattern. Only jiggling in place, but not having enough motion to get loose of their own place and to break the structure down. And that's what I'm describing as a solid - it's ice - it has a structure. If you held the atoms at one end in a certain position, all the rest would be lined up in a position sticking out and it's solid at the end. Whereas if you heat that hotter, then they begin to get loose and roll all over each other, and that's the liquid, and if you heat that still hotter and they bounce harder, then they simply bounce apart from one another and they're just individual - I say atoms, but it's really little groups of atoms, molecules - which come flying and hit, and although they have a tendancy to stick, they're moving to fast - their hands don't grab so-to-speak as they pass - and then they fly apart again, and this is the gas we call steam.

You can get all kinds of understanding - when I was a kid - with this air, which I was always interested in - I noticed that when I pumped up my tires on my bicycle (you can learn a lot by having a bicycle) you pump up the tires and the pump would get hot. And also understand that as the pump handle comes down and the atoms are coming up against it and bouncing off and it's moving in, the ones that are coming off have a bigger speed than the ones that are coming in, so as it comes down each time they collide it speeds them up, and so they're hotter. When you compress the gas it heats. And when you pull the piston back out, then atoms that are coming faster than the piston feel a receding or sort of a give - it gives, and comes out with less energy. It's like going up against something which is soft and yielding, it goes boomp boomp and it loses. So as you pull the piston out and the atoms are hit, they lose their speed and they cool off, and gases that cool when they expand. And the fun of it is that all of these things which you notice in the world - the pump heats the gas and whether the gas cools or expands, and steam evaporates until you cover the cover, and all these things - you can understand from these simple pictures.

And that's kind of a lot of fun to think about. I don't want to take this stuff seriously, I think we should just have fun imagining it and not worry about - there's not teaching when I ask you questions at the end, otherwise it's a horrible subject.