studiot

If the underlined proposition were so then all of science is based on one or more acts of faith. Godels Theorem tells us that about Mathematics, and applies to anything founded on it. This is of no consequence if the mathematics is an abstract construct, since we can change the founding parameter at will, and arrive at many systems of maths. But Science is meant to enquire into of which physical reality which we would like to think unique.

Darn I thought I had it all bottled up in my hip flask that I keep for April whisky.

Be aware that mathematicians have a much more general definition of the word 'Field' than physicists. For instance in maths the real numbers form a field, but in physics they would be called scalars or zero order tensors.

Negative effective mass. This is not quite the same as ordinary mass.

More help here http://forum.allaboutcircuits.com/threads/clarify-semiconductor-posts.101255/#post-764638

Vexen, one more piece of honest advice. Don't feed the trolls.

Remember that the drain, source and channel are formed from a P type substrate to create an N type region and vice versa. That is the channel and substrate are not the same element of the final MOSFET.

All of the stuff that Enthalpy and others are quoting are interesting but due to external agents, not the mechanism of rocket action. If this question was about how does a rocket work then you need to discount external factors and agents. If the question can be widened to include how to best use that rocket action then rock on.

Please note until today I was unaware of the referred thread as it is not my scene. So I have not contributed to it in any way. First I am going to take your opening post at its face value and say +1 for trying to address the issue. Unlike us from the Old World, New Zealanders are amongst the most isolated and therefore most insulated from traditional predudices. One offered a fair and friendly critique of your discussion. Did you read it? If you did read it can you see the difference between your posts and his and why the difference in the red and green votes? No-one has credence until she had established that she can offer well thought out statements, based on knowledge and rational thought. This may be already established elsewhere if the person identifies themselves as a known expert in that field. Otherwise you should seek to establish your own credentials here by making such statements and comments. The green marks will then flow of their own accord.

All you need is to place an expanding drain pipe stopper in each downpipe before starting and then flush with water at the end.

Hellow Andrew, If you mix water and wallpaper paste powder you can make it as sticky and thick as you like. You will need to tell us more about your project if you are looking for a better answer.

Well first remember that the channel is a length of unobstructed resistive semiconductor material. So current will flow through it if it is connected into a circuit. The channel also forms one plate of a capacitor, the gate of the MOSFET forming the other. So if the gate is connected to a voltage (relative to the source) ie has a charge placed on it then that charge will induce an opposite charge onto the channel. This opposite charge will add to or detract from the current already flowing. But this only occurs if the MOSFET is connected into a suitable circuit. It does not happen if the source and drain are not connected into a circuit, as with any other capacitor. So the simple answer to your question is that the electrons or holes come from the rest of the circuit that the source and drain are connected into. Remember also that the channel can be N type or P type, enhancement or depletion (less common) and that some FETS require a voltage to stop drain source current flowing. Go well in your test.

Dilution with water is the connventional way of dealing with common or garden bleach concentrate. About 250 parts water to 1 part concentrate by volume is about right for your original strength.

Why does it have to be either or? Surely a good chemist (or any other scientist) will employ any and all valid methods appropriately, comparing the results and perhaps even developing new methods as a result?

Pymander I offered a concise reasonable and polite quick reply to your question (post#3). You did not respond or even to acknowledge it. I then expanded on my short response (post#17) and again politely asked a simple question about whther your original question was about historical development or the present day (which was as you originally presented it). Again your silence was deafening. Most of your posts in this thread seems to me to be longish outpourings of unrelated statements that may or may not be true, but would require checking if anyone felt they had relevence. If you wish your issue to be taken seriously you need to pull these disparate statements together to present a coherent flow of logic, explaining the reason for bringing them up. Two books by eminent professors on the subject you appear to be addressing, but are not too technical, which make these conenctions rather well in an unbiased and factual manner thus making them believable are The Day the Earth Nearly Died by Benton Eruptions that Shook the World by Oppenheimer

Perhaps the assumption that the acceleration is always in a plane through the centre from which the position vector r is measured should have been stated explicity.? Perhaps more interesting, is the assumption Since c is a constant we have [math]\frac{{{\partial ^2}{X_{32}}}}{{\partial {t^2}}} = 0[/math] In other words the acceleration component in the third dimension is zero. But at the expense of a constant light speed in the third dimension. Perhaps some additional words of explanation would not go amiss? Perhaps also using g for the generalised acceleration rather than another symbol will lead to confusion with gravity?

The mineral concentration occurs due to chemical reactions between the water circulating in volcanic zones and the hot rocks. http://nzic.org.nz/ChemProcesses/water/13A.pdf

The mineral concentration occurs due to chemical reactions between the water circulating in volcanic zones and the hot rocks. http://nzic.org.nz/ChemProcesses/water/13A.pdf This should be in Earth Sciences.

Another way to analyse this is to consider a momentum balance. The rocket plus its fuel starts off with zero momentum. As the fuel is burnt the exhaust is expelled backwards and the rocket moves forwards. The momentum of the backward moving exhaust equals the momentum of the forward moving rocket. This balance allow you to calculate the maximum speed attainable for a given fuel load, or how far the rocket can go before it has to turn round if it is going to be able to return.

Well you are asking about a set of four simultaneous equations. The set are shown in the upper part of my attachment, could you not have done this? You cannot fully solve ODEs without boudnary conditions. It would seem that the next few equations specify these boundary conditions, as shown on the next page, at the bottom of my attachment. However there would be a great deal of reading for anyone to become familiar with these equations, you need to flesh out your post in order to hold, a sensible discussion. What do the symbols stand for?

As a matter of interest why is this thread in speculations? So far as I can see it is not a proposal, but a discussion about scientific progress and the scientific method and all the better for now being back on track. So I would think it part of the philosophy of science. As to the relationship between theory and practice, IMHO they go hand in hand. There are many examples in history of one getting too far ahead of the other with undesirable consequences. Plato's theory of shadow's in the cave had too much theory and tool ittle practice. The observations of the motions of heavenly bodies originally had too many observations and not enough theory.

Concise and fairly balanced. Thank you Mike for keeping the verbosity down to the technical. +1 In particular I endorse the question (underlined in the quote) as to the lead player in modern times.

Bill Angel Thank you, Bill for the thought. Negative mass is indeed an interesting subject. Certainly sticking a negative sign in front of something that Physics takes as non negative but is allowed in Maths is worth thinging about. Unfortunately I'm not sure it shows a difference for negative mass since negative (effective) mass is already in use in Physics and important in semiconductor Physics amongs other places. But there may well be some negatives that are OK in Maths but not Physics. Acme Thanks for the contribution Acme, Again unfortunately I don't see where Physics forbids irrational or trancendental numbers. Both the radius and circumference of a circle are real world objects. Incidentally this thread was stimulated by preparing a response to a question about the origin of energy bands in semiconductors.

I am collecting examples of where maths and the physical sciences differ over something. Examples offered would be gratefully received. For instance cos (z) = 3 has no solution in the real world and this fact is of vital importance in creating transistors. However in the mathematical world the equation has complex solutions.

Maybe you are focused on something, but the title of this thread is about two things. Mathematics v Observation and Hypothersis. Observation represents Physics which represents the real or concrete. Mathematics represents the abstract. I didn't see any reference to Art or English in that title, or the original post. I would suggest that rather than combine hypothesis with observation I would say hypothesis represents the link between the abstract and the real.