Fozzie

I interpret your question to be "why does air rush in to a space which previously was a vucuum". Simple. It's the pressure of of the air pushing from the outside, not some "force" within the void which sucks!

On the BBC's Science page "Herschel space telescope captures birth of stars" which can be found at http://news.bbc.co.uk/1/hi/sci/tech/8416263.stm Palab Gosh (BBC Radio Science) who has a science degree from Imperial College narrates a short video where he states that stardust is seen "forming into clumps along magnetic lines". He goes on to talk about "magnetic eddys" when describing how the dust forms a new star. Please correct me if I'm wrong, but I always thought it was gravity that did the "clumping"!

I have read in several articles that "As a substance is heated, the atoms and molecules that make up the substance vibrate faster." Now, Newtons Law of Inertia states that "A body persists its state of rest or of uniform motion unless acted upon by an external unbalanced force." So what is causing the vibration?

So I presume a superposition of states must be purely theoretical, because once you take a measurement, as you say, it isn't in just one state until you actually measure it to be in that state. So was this superposition theory derived mathematically?

I have only recently become familiar with this concept, so please forgive me if my question seems daft. Schrödinger wrote "Until the box is opened at the end of the hour, we will not know what has happened. According to quantum law then, the cat is both dead and alive, in a superposition of states. It is only when we break open the box and learn the condition of that cat that the superposition is lost, and the cat becomes either dead or alive. It's the "both dead AND alive" bit that I cannot grasp. Why not "dead OR alive" because at that stage, we still don't know, so the answer has to be OR, as there are two possibilities. To take another example, before a tin of beans it opened, it will either contain beans, OR it won't. It can't be full and empty at the same time. So why is it necessary to use this play on words?

Thanks, I guessed it must be something like that. So the next question is what are the advantages and disadvantages of the two systems?

I have just watched a news video of a Soyuz rocket taking off from Baikonur and noticed that there is no trail of smoke like you see on the American launchers. It left the sky quite clear. Why is this?

Thanks, but you lost me in the first sentence. I didn't do physics at school. What is a reference frame? Imagine you are explaining to your 90 yr old granny.

I think it's Stanley Unwin!

At http://news.bbc.co.uk/1/hi/sci/tech/8040073.stm there is a diagram which shows the Herchel and Planck spacecraft orbiting the L2 lagrange point. I am puzzled by this as there is no solid body with any mass in which to orbit around. Could somebody please explain what is going on to a non-scientific mind? Thanks.

OK, so if I plot a graph with gravity up the side and distance to the centre of the earth along the bottom, I would get a line falling from 1g to zero g. The question is, would that be a straight line, or would it be curved?

I'm sure this has been asked before, but I can't find the answer right now. If you stand on the moon and face the earth, you will feel the attraction of the earth's gravity (as well as the moon's). If you then move towards the earth, the force of attraction will increase until you reach the earth's surface when the force will be 1G. If you then burrow into the earth, the force should increase above 1G because you are closer to the total mass of the earth. If you then continue downwards, at some stage the force will start to decrease because it must tend to zero at the centre because it must then increase in the opposite direction as you ascend the "other side" until you reach the surface when the force will again be 1G, but 180 degrees in direction to what it was at the "other surface". If you then plot a graph of the strength of the force against distance from the centre of the earth, what shape would the graph be? I can only see this making sense if you take the direction into account and so plot the force and direction together - ie as a vector. Any ideas?

Can someone answer a question which I have pondered over for some time. My wife covers the bathroom radiator with her towel. Does this increase or decrease the cost of heating the house? The hall thermostat is set to 20 deg C. My thoughts are that if one radiator is insulated in this way, the boiler has to work harder by heating the other radiators to maintain a house temperature of 20 degrees. On the other hand, because heat is not radiated away from the radiator in the bathroom because of the towel covering it, the hot water in the system stays hot longer than it would have done had the radiator not been insulated in this way, so the boiler doesn't have to work so hard. So what's the answer?