abskebabs

I have my own ideas about what these could be. Could you offer some specific ones you know?

Would you agree then, that government should stay out of this entirely? Awareness of this issue can be raised, but when it comes down to it, should the action to reduce global carbon emissions be carried out entirely by individuals reducing their own consumption? Personally, I think some of the "solutions" raised hav been short sighted, e.g. subsidising one industry as opposed to another. An example of this can be seen from the subsidisation of Ethanol or the proposals to subsidize nuclear power in the United States. I think that "Green Energy", however can be looked at as a investment, by responsible governments. For example, a sort of tariff scheme I read about a year ago that was being applied in Germany I thought was quite smart, whereby Gas and Electric companies would be charged a certain amount for every amount of electricity they supplied by nonrenewable means, and this same money would subsidize energy from reneweable sources. The tariff placement was temporary however, designed to increase the amount of energy from renewable sources, which has been increasing with the help of this. I guess it could be used as a "spur" for the industry to get it's act together. On the other hand, I know from reading an article a while back, were an executive from a solar company was asked the best thing the government could do to helps spur growth of his industry, and his response was to stay out of it. Personally, I can understand if people would not be eager to implement such schemes, but I certainly think any remaining subsidies supporting non-renewable fuels should be removed promptly! (On a side note it's funny, how I can post a thread in the Classical physics subsection of this forum, and not get a reply for 3-4 days so far, but get one almost immediately in the Politics subsection:rolleyes:. Not that I'm having a rant or anything:D)

Did you actually visit the page Blade, or did the sensationalist title put you off? I don't agree with how they propose to tackle the problems they mention, but I do think there are problems with the conglomeration of news media. Also, I think you were being a little quick embracing CNN as some sort of "holy grail" of unbiased media, as I think that is pretty far from the truth. I don't even have a problem with news media being owned by a few companes as long as there is no chance for intervention by the government into their businesss. This reduces their incentive to "meddle", and politicise the news. PS: Sorry for digressing to this issue, I know I should probably start a standalone thread if I want to discuss this issue more.

I know that many political commentators around the world, and especially in the US still doubt anthropogenic global warming and strongly oppose any measures to try and reduce it like the Kyoto protocol, and measures suggested along the lines of implementing a crbon tax. My question concerns primarily this: Why is it the conservative political movement, particularly the paleoconservatives, so vehemently deny that global warming is taking place? Personally, I agree with a lot on economics, and questions concerning goverment regulation and interference with the market, with Ron Paul, who does himself deny global warming occurring and has support from a lot of paleoconservatives. I guess, if I were to guess the ideological reason for such an opposition, is that it goes part and parcel with opposing government interventions and regulations into businesses on a large scale via the implementation of a global carbon tax. Would you agree with me on this? Do you think people like Alex Jones, would probably not make an issue of whether this was occurring or not, if such "big government" solutions were not being offered as a way to tackle global warming.

You might be interested in assessing the following link: http://www.cnnexposed.com/why.php

If you're still following this thread, I can recommend 3 books I personally found very useful for relativity: 1. Introduction to Relativity by William D. Mcglinn 2. Spacetime Physics by Edwin F. Taylor and John Archibald Wheeler(easier to follow, but more wordy than the 1st book IMO) 3.Physics in spacetime : an introduction to special relativity by Benjamin Schumacher.

I was revising vector calculus recently, and couldn't help but incorrectly have a train of thought about its interrelation with the calculus of variations, and the relevance of both in Mechanics. After thinking about this for a bit of time, and resolving some of my previous confusion I have ended up with a simple question. I have learned that a quarter of a cycloid is the curve that satisfies and is a solution to the Brachistochrone problem for when we assume gravity to be constant. However, I was wondering, what kind of curve is a solution to the same problem when we don't assume g to be constant, and take the familiar newtonian expression for it? Also does this bear some reference to the study of orbits? I would hazard a guess, that half the shape of a comet's orbit would be something close to the solution for this problem, and therefore that the curve would be a hyperbola. I'm not at all sure about this though, and am already doubting the validity of my previous sentence. So, any ideas?

I know that I am multiple posts too late for this, but I thought you guys could have been a lot more succinct by just saying: The planets can be thought of as having a tangential velocity and constant speed. Note the difference in terms here, because velocity is a vector quantity. The planets experience a central force (in this case their weight), causing the mass to experience an acceleration(both force and acceleration are vector quantities). The acceleration, however, due to a central force is orthogonal to the tangential velocity, and therefore has no effect on its magnitude, causing it only to change direction. The orbit produced is approximately circular, when the central object(like the sun) is much more massive than the object in orbit. Otherwise, the orbits are generally elliptical, and sometimes hyperbolic(in the case of comets, though correct me if I'm wrong).

I guess this may depend on your prospectus search engine, but not even the inertia tensor came up? That should be covered as that's CM. Also I'd think any respectable later year course on EM should have tensors too.

I agree with that.(sorry if what you were saying was a joke), but I think the US is getting much closer to corporatism than real capitalsim. I think a better example of true capitalism was Hong Kong before secession to China(maybe it still is).

Hi Snail, I think to a broad extent you're right, but I think what you're talking about extends beyond just General relativity(I think QM is another great example of this). I'm in my second year and we finish having a stand alone maths module this year, the rest I think is taught "on the go" in a way, though we do have specific modules dedicated to things like PDEs and specific maths. As for SR, I covered it twice in the 1st year and the treatment was basic in one module, and more complete in the other, doing as much of relativity you can do without properly invoking linear algebra and tensors(because we hadn't been taught it yet). I asked one of my lecturers concernign the maths involving general relativity and he said as we also have a relativity module in the 3rd year, the whole linear algebra/ tensor and geometry approach to it is built up in that year. This is before the course on GR in the 4th year. So, I guess my answer is yes, we do have a GR course in the 4th year at Birmingham, it's compulsory for me because I do Theoretical Physics. Not sure how cursory it is yet, but I'd like to think it isn't very... On a separate, but related point I think we don't get taught enough maths in our school system, so that when it comes to uni, most of the early maths is just catching you up with what undergraduates in the past already knew. Saying this however, I must admit I am a product of the British education system myself, and I chickened out from taking further maths at A level:doh:.

Woohoo:-) ! One of my lecturers is on that video!

Hello everybody. I'm a 2nd year undergraduate in Theoretical Physics, and I have to write a 2000 word essay on an area of physics, or something physics related. I am currently undecided on what to do, and I have 2 weeks left in which to do this work. I have come across the theory of broken symmetry, but do not know much about it, and the article on wikipedia is especially brief. I am considering whter to do my essay on it, but would like to find out more about it first. Does anyone know any good introductory sources? My essay is not required to be especially rigorous, I am just required to have a reasonable grasp of what I am talking about and most of the marks will go towards getting the right "style" for a scientific essay. In light of this, would broken symmetry be an unsuitable subject due to its complexity? If I am to research it, are there any areas of mathematics I should brush up on first before diving in? Assistance with regard to this matter would be greatly appreciated.

Do you think some delusions may be beneficial(to a limited extent)? I've posted about this before; but I remember New Scientist articles a while back talking about research showing things like women who thought they were pregnant experiencing greater happiness, and I guess mental health while they still believed in their delusion. This is the placebo effect to cut te story short, but mental health does make an impact on physical health right? I was under the impression that's the reason why they're now trying to make NHS wards look a little less drab and depressing nowadays, as it helps speed up recovery time. Please correct me if I'm wrong. A similiar argument could be made with religion in some cases, if I know that my death isn't the end, or let's say my life is pretty awful but it may cheer me up and help me get through the day if I know there's a heaven. I just get the thought in my head when some people expound th reasons they are Atheist, that you know it's easy for them to live with and declare such a conclusion, compared with someone in a much more desperate background. I'm an agnostic atheist(as defined by others on this forum), but I do respect THIS aspect of religion. However I get just as annoyed as anyone else on this forum, when people will try to miscontrue facts and reasoning, or even worse, lie about them to support their prejudices.

My comment was irrelevant to whether the initial figures he obtained were correct. I was simply stating(pedantically) that 100-0.004=99.996; not 99.006. Honestly, my lecturers love me:-p . I haven't a clue if the initial figures are correct.

I'm sorry to be a pedant here:D , but isn't that 99.996%? I'm just surprised you repeated his error tbh.

I must say that despite the fact I am not American and live in the UK, I have been enthralled by developments in the American presidential race, and most specifically the campaign of Ron Paul. In fact I think it has turned into an addiction as I have spent shameless hours scouring the internet, especially youtube for coverage of this candidate... In fact part of the reason of making this thread is I fell that talking about my ailment may help me tackle this perhaps, and let me do more useful things with my spare time:embarass: ... Has anyone else felt a fascination with this candidate, and is undergoing a similiar craze, not just in terms of how rare such a politician is, but also about how much he has educated people(I tout myself as an esample), on things that were previously pretty obscure like the details of free trade and monetary policy? Do you think his campaign could pick up following his mediocre showing in Iowa, and his poor one in New Hampshire? Could perhaps some sort of alliance with Dennis Kucinich, if he ends up dropping out of the democratic race, and do you think this could help his race? I feel discussing this on a forum could perhaps be better than me scouring news and blog articles on the web for another 2-3 hours on this.... Whew! It feels good to let it out. I think I'm gonna go outside now to just clear my head and get some shopping done. I look forward to your replies;)

It's not just for politicians and lawyers you know! I like how English allows for so many plays on words, and allows for so many amusing jokes, double entendres, innuendos, sarcasm and a wonderland of stuff;). Not sure if I'm going to shamelessly try one here though.... inyourendo:-p . Also to anyone who's missed me, or even noticed that I haven't posted in a while Hello:D

It's taken me a while admittedly but scrolling through this old thread I've realised that my initial difficulties with this were not resolved. Could someone else have a look at this and try to help me out please:-) ? Thanks in advance

Martin, for your benefit, and especially for people unfamiliar with the subject matter, I thought I would outline what I understand by similarity dimensionality. Suppose we start off with a line of length 1. We can split it up into N equal pieces each of length 1/N. Now if we represent(arbitrarily in this case) the number of pieces by the letter k, and the inverse proportion of their length(basically 1/length) by say, F, then we have by similarity dimensionality: [math]k=F^d[/math] Where d represents the number of dimensions In our case however, F=N, and K=N; so the line is 1 dimensional. We can take this same process and now apply it to a cube. Along the 3 connecting edges at a corner of a cube of length 1 suppose we split the lengths of the edges into N different segments, and make marks to represent their boundaries. If we imagine cutting the cube straight along these marks, we end up splitting it into [math]N^3[/math] pieces. Having done this, we see that now; [math]K=N^3[/math] and[math]F=N[/math]. Therefore we have: [math]N^3=N^d[/math] so we don't have to take logs to see that the number of dimensions is 3. Now that I've established this, I will show how it can be used to look at the dimensionality of a more solely mathematical, but simple object, namely: the Garnett set. Now the Garnett set is the union of all that is covered by the following operation carried on infinitely on a square: Take a square of length 1(to start off with), and take from it 4 squares at each of the corners, each square of length 1/4. For the next step I would take each of the 1/length squares and carry out the same procedure. This process would then be carried out to infinity as indicated above. Therefore after doing this k times I would have[math]4^k[/math] pieces each with a length [math]4^{-k}[/math]. Just like the ordinary cases I have already described above we can define the self similarity for the Garnett set just as well. We notice at each stage the square is split into 4 more pieces each of length a 1/4 of the square from which they were constructed. Therefore we have k=4 and N=4! So; [math]d=\frac{ln{4}}{ln{4}}[/math] therefore d=1. The set is 1 dimensional in terms of self similarity. Now this kind of result I would never have intuitively guessed if someone asked me about dimensionality. I was thinking a lot when I first saw the results, and I guess I came to terms with it when I faced up to the fact that when we define a notion of dimensionality like that involving self similarity, we can then import that and apply it to a wide range of more abstract objects or phenomenon. But I didn't see THIS type of dimensionality necessarily having any physical significance(especially with regard to what I have referred to as more abstract objects), and I guess I feebly attempted to suggest my feelings about this before now. Martin, I notice you gave the example of a sphere when defining a notion for self similarity. For my own satisfaction, I think I will just try to find or confirm its dimensionality within this thread: Ok, so we have the radial length of say 1. Divide along the length into N equal portions. The volume of the sphere will be [math]\frac{4}{3}\pi*[/math], so we should have [math]\frac{4}{3}\pi*N^3[/math] "pieces", however I recognise that this would only be true if we were talking about how many cubes of length 1/N would fit inside the sphere. I suspect I would get the result you no doubt expected if I tried to divide the sphere into spheres of size [math]\frac{4}{3}\pi*\frac{1}{N^3}[/math], as [math]N^3[/math] of these spheres would produce an equivalent volume. But conceptually, I see no sensible notion for how to subdivide the sphere into these "mini-spheres", as wouldn't it be impossible(at least if they were to maintain their shape, and hence self similarity)? For example, I can imagine(me and my interesting life:-p ) trying to fill a large sphere with [math]N^3[/math] smaller spheres each of radius [math]\frac{1}{N}[/math] of the large sphere's radius, but this would cause it to "overflow", and I wouldn't be able to completely fill the large sphere with them because of the inherent gaps that appear. Therefore, I think I can kind of give you an idea after this terribly long post why I don't think the notion of self similarity dimensionality can be as easily defined self consistently, at least on an elementary level for spheres as it can be on cubes. Instead, I feel the notion could be "abstracted", to give the expected conclusion(that the sphere is 3d). Please tell me your thoughts on this. Phew!

Think I'll pass. I don't really want to "take sides" in this seeming tribal warfare going on, but I can't seem to finish reading those threads even when I try really hard.

I must admit, I didn't know much about this book, partly from my own ignorance I guess, but from reading this discussion it sounds riveting! I think I'll keep an eye out for it as I normally would avoid popular science.

Thanks for the response, I think I understand now. The example you gave perfectly illustrates your point. 30031, would be considered a prime number if 2, 3, 5, 7, 11 and 13 accounted for all prime numbers. But they are not, and so the number could be prime(like I assumed), or could be divisible by another yet unknown prime, as you mentioned(in this case it was 59). The same seems obviously true if we try to suppose the same for the set P of all primes, as you have already mentioned(sorry to be a parrot). I can see why the "formula"(or its alternative version) cannot be used to generate primes, as it is simply for the purposes of showing that there cannot be a finite set of primes in the proof of contradiction. It's been educational:-)

I'm currently revising for a resit of my Impact of Maths module which I took this year and I found really hard, especially for a module outside my main discipline. This could explain a few of my recent posts:-p . But I have just been doing a question from the book which I am using to revise for half of the course, called Mathematical Puzzling by Tony Gardiner. The question was: "3 and 5 differ by 2 and are both prime numbers. What is the next such pair? How many such pairs are there like this?" Interestingly the 1st thing I thought of was 11 and 13:doh: . I kept looking for pairs though, and it didn't seem like there was necessarily a limit. I looked in the answers, and it said that it has been conjectured that there were an infinite No of such pairs but this has not been proved. Now I already know that a product of all "known" prime numbers added to 1 produces a prime, and this constitutes the proof that there is no largest prime number. I had been pondering this before, but isn't it true that you could take the same product of all "known" prime Nos and subtract 1 to produce another prime? Because the difference is again only by 1, the nearest prime factor of 2 would still not be a factor of the resultant No, and hence it would still be prime, wouldn't it? If this is true as well, then(deep breath); Doesn't it constitute a proof that there has to be at least an infinite No of such pairs because both of the above described formulas for generating primes could produce an infinite No, and for the same number of prime numbers could produce an infinite number of pairs that are separated by 2. The conclusion seems so trivial, that I suspect I have been naive here and made a mistake. Or perhaps, the conclusion is not really so out of this world, I don't know. I would be very grateful if someone more mathematically advanced could enlighten me on the validity of what I have so far stated on this thread.

To be honest with you Dave, I have only recently(i.e. this year) come to understand the meaning of similarity dimensionality, and that itself was something short of a revelation, because it exposed to me how little I had thought of the notion dimension properly before(In fact I would recommend people unfamiliar with it to look it up as it's fairly simple, and could give you some real insight). It's amazing really. I may read up more on Haussdorff and box dimensionality in the near future(as at the moment I consider myself only very vaguely familiar with them) to give myself a better idea, and so then I can ask you questions a little more specific and perhaps less redundant. When our lecturer went through similarity dimensionality, it really struck out for me how we could take a notion in how we define the conventional Euclidean 1d to 3d spaces, and then abstract our notions to other self repeating pictures for lack of a better word. Anyway, I thank everyone for taking an interest. If I don't forget about this thread, I may come back to it later.