studiot

Oxford Calling

Hydrogen, Acetylene and ethane are all gases at STP so 0.1M is an unusual way to measure concentration. Any information on this ?

I think I need a holiday. First class catch, I misread the reply. + 1 😳

OK so you need the coefficient of restitution. This pdf is an advanced treatment, but includes explanation of the basics. http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.402.4689&rep=rep1&type=pdf Note the poly tube will be in compression not tension at impact.

Depends upon if you are considering an elastic or inelastic impact ?

Is this homework ? Patterns, fingerprints, retinal scans, captcha type Q & A ................

Indeed theoretical physicists at Oxford University have a whole department studying "The Science of Can and Can't" under David Deutsch. Stangely no one else seems interested in my thread on that subject.

Thank you for the response. I look forward to hearing what others have to say.

This to introduce a discussion on the proposition that Philosophy is still valuable in this day and age, dominated as it is by scientific considerations. Some have argued that Philosophy has become redundant in modern times and that Science can somehow replace all its functions. I argue that this is not the case, but that the issues have moved on for some and we would be well served to stop re-enacting old battles and put our efforts into new matters. By way of example here is a sequence of instances culminating in a modern day issue. The ancient Greeks were so distressed about irrational numbers that they tried to forcibly suppress knowledge of them. In the Middle Ages, a similar thing happend with the discovery of imaginary numbers. In the late 19th and early 20th centuries Science learned to exclude uncomfortable matters 'by definition'. Today that exclusion process is being applied to 'information' and full consideration of its nature. I argue that Philosophy offers an independent forum for the conduction of such consideration, regardless of how useful and successful a tightly conrolled scientific definition might be.

And thereby lies a mathematical contradiction. Mu-nought and epsilon-nought in your formula are scalar constants. That means they are independent of direction. The condition for them to become direction dependent is that they are no longer scalars but in fact tensors (not even vectors will do). This is in fact achieved under non isotropic conditions. However the rub is that there is no such thing as the square root of the ratio of two tensors.

Hopefully the trash can is not quite full yet. I would recommend anyone who would like further informatuion to start their own thread, rather than try to disentangle this one.

I thank you for responding to one thing I said, but I am sorry that you simple demonstrated that you don't know what you are talking about. If you want more explanation all you had to do was ask. Instead you chose, yet again, to challenge an attempt to help with nonsense. How can a point in space be counted a zero ? This means that if I label a point 'zero' and I am counting points that I have no points ie you are saying a point is not a point ! I am becoming weary of putting time and effort into this to no apparent purpose.

The first two lines are not true. I recently quoted Euclid axioms which state exactly the last line to someone. Was that someone yourself ?

I agree with both you and swansont, however I was holding off infinity until we had determined other definitions since CE is mixing up physics and maths, as several people have now commented. It should also be pointed out that there is more than one type of infinity (or meaning to the word) which makes things more complicated. I have already pointed out the easier question that we need CE's definition of natural numbers. So thank you for this @Conscious Energy OK so you wish to include 0 in the natural numbers. That is fine. Some Mathematicians include zero some do not. Personally I prefer to start at 1 because it makes the philosophy of numbers easier and more elegant. Either way we can state the following axioms to obtain all the natural numbers. 1) 0 is the first number. 2) Every number has a successor number, obtained by incrementing that number by 1. It follows from these two axioms that 0 is the smallest natural number but there is no largest natural number. This leads directly on to one type of infinity as a non terminating process.

Yes and I have several books on the philosophy of the Natural Numbers, along with large sections in many more maths books. You are using a different version of the Natural Numbers from the rest of us. You have not answered my question: Further, just because this is the philosophy section, it does not entitle you make make unsupported claims such as "youcannot have space without time", most especially not in support of other wild musings. You have asked several such questions and been answered before. Even though, just like with the Natural Numbers I do not know what you mean by the much more difficult notion to tie down, that of infinity. Be all that as it may, I will offer you some hopefully useful thoughts on these questions. But they will only be useful if you take some note of them, instead of immediately trying to challenge them with unconventional interpretations of conventional definitions. OK so space, with or without time and Infinity for a physical object. Using zero and the positive integers we can propose temporal and spatial dimensions as follows: Let S1, S2, S3, S4.......... denote spatial dimensions. Let T1, T2, T3, T4.......... denote temporal dimensions. Then for each of 0, S1, S2, S3, S4.......... spatial dimensions we can propose 0, T1, T2, T3, T4.......... temporal dimensions Now we can do the maths of how each of these situations would operate, ie what our universe would be like if there were eg say only two spatial and one temporal dimensions, two spatial and zero temporal, two temporal and zero spatial and so on. Then we can do the physics and compare our observations on our universe to see which one matches our maths the best. Again there are many books and meaty subsections of books and papers doing exactly this. The results of this is why we believe our ordinary sense impression that there are three spatial and one time dimensions. For any other combination we can derive mathematical results we do not observe. OK so to consider an physical object existing in this 3 + 1 universe and the relationship to infinity. Let us say a building stone in a dry stone wall. Say we move this brick 1 metre to the left, so that instead of being the fourthe stone from the left hand corner of the wall it is now a cornerstone. What have we done ? Well we have changed its spatial position and in doing so did the stone disappear at any point in the move and reappear anywhere else or did it at some instant occupy every point lying between its initial and final position ? I would say we have no evidence that any stone has ever done the former but has only ever passed through every point on its way. So what links the initial and final points ? Mathematically the word is continuity. And continuity requires infinite division. Now you have mentioned Planck lengths. Swansont has told you that we cannot measure within a PL. But he did not say that the points in the space within do not exist, just that we can't measure there. And continuity requires the existence of these points. So by the mathematics of continuity (infinite division) we have a physical infinite. The interesting thing to learn from all this is that an infinite sum can add up to a finite total, which is the principal underlying 'limits', another specialist term that you are so loosely bandying about. Note the importance of recognising and taking note of what others say.

Surely it is time this thread was moved from physics to the rotary trash can ?

I asked you to be mathematically precise. So please avoid mixing up mathematics and other topics, particularly physics. This thread is claimed to be about the 'Natural numbers', which is a precisely defined mathematical description. Do you know what the natural numbers are ?

You need more precise mathematics for that. In particular you need to understand what is meant by finite and infinite. Every (individual) Natural number is finite. But the collection of all natural numbers is infinite.

You have been offered a lot of good thoughts and information about wind power. Have you investigated any of them ? What does a "boat with a turbine on all ends" look like ? There have been designs for 'sailing' cargo ships, as large as oil tankers, using one multiple fans of the type sensei described. and some prototypes have been built and tested. I do not have up to date results on these, but early indications were promising. However this is the energy to power one ship. Do you have any idea of the impellor size on a conventional wind generator ? It's diameter or radius is enormous, The stresses involved after turning the rotation axis to the vertical would be commensurately enormous at that extended radius. This fact once limited the size of sailing ships. A final comment. Why do you seek to extract energy from infrequent peaks in the wind's power ? Surely slow and steady but reliable is the way forward ? Especially if you wish the installations to last many decades.

A very perceptive observation, except I would not make it such an absolute statement, ie suggest A particularly productive part of the political pendulums swing is in the change of direction. +1 I vote contemptuous.

So start your own thread. PS my apologies for the poor spelling in my previous posts.

Yes good point. I haven't yet read the new 2021 book, so I'm keeping an open mind, and the idea may turn out to be just huff and puff or it may lead somewhere. So I have tried to give just the unarnished bare bones for all to assess.

This is better discussed in the politics section of the board, rather than the science section. I do believe I already said all this. But I also meant that the solution requires the will to implement it and that is socio-economic / political. Many changes will be needed, there will also be false turns.

This is the meat of the linked article from Quanta Magazine. Anybody interested in discussing this idea ?

Hello, jacobus and welcome. I note cheyennegregory hasn't been back since last March, but I see that you are both from the more northerly parts of the globe. I would recommend you both read this book by the late physicist, Sir Fred Hoyle. Fred offers calculations as to the energetics of both the starting and stopping of ice ages and then devotes several chapters to examining mechanisms that can lead to both starting and stopping of ice ages and most importantly the timescale over which occurs. I cannot stress enought the brevity of the starting timescale. This brevity is due to the energetics of solar radiation and partly, but only partly due to the solar and terrestrial relative positioning and requires another powerful event to activate the on and off triggers.