abskebabs

I think the Solvay conferences especially in the years during the early development of qunatum mechanics and relativity attained a high importance, like the 1st one in 1911, where relativity would have been the main subject of discussion. The most famous one by far though was the 5th conference in 1927. I am unsure as to how important or relevant they are to the development of modern science today though. There has probably been a great enough proliferation of such conferences toda that, there is little chance of there being "one big event".

I remember reading an interesting new scientist article that was on this same subject. Often we feel intiuitively that time passes at different rates according to the type and level of activity we are involved in. For example athletes often say they are "in the zone", and they seem to have more time even though time of course is passing at the same rate. There has just been some change in their perception of it. In fact a lot of recent neurological research has been done on this area, and so here are a few links you may find useful: http://www.newscientist.com/channel/being-human/mg18925371.700 http://www.newscientist.com/channel/being-human/dn11080-how-long-is-a-splitsecond-its-all-relative.html http://simon.lrdc.pitt.edu/~iccm/proceedings/papers/Taatgen.pdf

OMG:D ! Have I just quoted myself observing that this function displays chaotic behaviour? It becomes increasingly susceptible to changes in initial conditions as the order of iteration grows! Pls corect me if I am mistaken, but if valid this would be rather interesting.. but I'm not sure of the validity...

I've not done much so far, just a simple x-y plot with the the "angle" on the horizontal axis plotted against several functions of tan, each with a different degree of iteration, as well as x itself. If you want you can have a look at it, I have attached a screenshot JPEG of what I did, as unfortunately I cannot upload Mathcad as it doesn't seem to be an allowed file type. Nevertheless, I think you will find it quite interesting(I myself was pretty excited during the process ofdoing this:-) ). For example there are regions or "starting values" of x at which the iterated functins all join up as can be seen graphically, and do actually tend towards a certain value. There are also other regions which go through "cycles"(I don't think they're necessarily periodic in terms of the order of iterations but they do tend to go around the same range of values), whereby they may start off at a certain value of x,e.g. 0.3 , you keep using the tan function and it tends towards a certain value before making a jump to a different value(with the tan function this usually turns out to be -ve and close to -pi/2). A lot of this was found just messing around with my calculator, but I felt gladdened seeing it graphically. I will try and get up to scratch with cobweb diagrams, logistic maps and phase diagrams by reading up my chaos module, before I attempt to do anything more advanced. Also I will need to learn how to do these on Mathcad too! If you know how to do this though I urge you to give it a try though. Pls tell me how you do. There is whole host of interesting behaviour I have not yet mentioned, but I leave it to interested observers to have a look at this and see for themselves. EDIT: As you can see I've fiddled with the limits a bit to produce a raph with a more reasonable scale, as I'm not interested in where the functions tend towards infinity. Also you may notice that if you alter the division between values of x, it drastically changes the graphs you see, and the dependency grows as you increase the degree of bifurcation.

Thats a fair point, and I thik broadly I do agree with you, as Iran and all other nations should be judged mainly on how they treat their citizens and their citizens' welfare. But I think the history of the civilizations and empires that happened to inhabit this geographical area is nevertheless the history of the ancestors(more or less, due to the effect of migrations) of the ppl who inhabit Iran today. In fact I think this persian legacy and history has been repressed, along with the attempt to replace farsi with Arabic(which didnt work), along with the state sponsored persecution of Zoroastrians. Regardless of the fact the regime are the absolute antithesis of this region's past, it is still the history of the ppl of Iran in my opinion, and most of them acknowledge this and are proud of it too. Why do you think they get pissed of when Persians are represented in a less than admirable fashion in Hollywood(examples include overhyped, grossly dumbed down"masterpieces" like 300 and Alexander). Hell its even amusing when elements in the current Iranian regime express their disgust at these movies, even thugh they are actively suppressing this "culture", for the lack of a better word themselves. To be fair though this process has been ongoing since the arrival of Islam, and has just intensified in the last 30 years. The best situation I can think where this broadly isn't true that I can think of; would be with regard to US history before colonisation, as the vast maority of the citizenry before this date would not have had an "American" history. Of course the same applies to different extents throughout the Americas(and to a similiar extent in Canada". Many of the Iranians I know(admittedly students) come across as having a lot more in common with this past than the present "Islamic state". Hell they even have drinking customs in an Islamic state! Also on another note; I saw a 5 news broadcast earlier today where they revealed an interview they had with one of the captured sailors prior to their capture. He talked about how they were carrying out intelligence gathering operations on the Iranians in the area. I thought 5 deserve due credit for this sensible and smart journalism, as it could have poured oil on a fire if this news was revealed prior to the soldiers release, and made the situation more precarious. In fact if this footage was available earlier, I'd wager many a hardliner in the Iranian regime may have wanted to use this footage to back a kangaroo trial to prosecute the sailors for spying. I hope they're livid about this:D

Personally, I don't read too much into how both politicians appeared at their respective press conferences, and I don't think that is actually too important, just what happened "on the ground" that counts. You have your opinion on that, I've given mine. There are several possiblities available for the actual decisions that were made on both sides that led to this debacle, but frankly all the speculation in the world will lead to just that; speculation so I won't dwell on that issue at the moment. Hopefully things may get clearer over the next few days. I'm glad you take such a strong position on women's rights:-) , but I dont think it grants a blanket dismissal of middle eastern history or culture outright(or any for that matter), though admittedly things at the moment are far from desirable. Just remember, for example; during Saddam Hussen's tenure(not a glossy one btw), Iraqi women enjoyed equal salaries to their male colleagues in the same positions. This is something that is still not paralleled and stil an issue in the west. But Iraq today is by far the best example of what you are talking about.

You make a fair point, and maybe this is a deeply engrained part of our coolective human psyche "to root for the underdog", as it were and generally despise those dominant to us, particularly if they are fewer. Personally I am sick of it all, ppl suffer far too much in a pointless process. If I could, I would ban all nations starting tommorow, though admittedly, much careful thought would need to go in to how to replace them. I sitll think ppl themselves have a lot of power and can make a lot of change for the better even within the confines of our existing system. This "ppl power" can be exemplified by how disaster donations from individuals collectively amounts to much much more than that donated by national governments in the event of national disasters or catastrophes. Hopefully things will continue to change in the positive ways that have already begun this century, and we will never be engulfed in a tide of ignorance and prejudice again.

Problem is conflicts really have very little to do with right or wrong, in fact I cannot think of any that are really based on that. Nations, empires, whatever you call them have since the dawn of time have always served their own self interests, or their ruler's or political class's interests(to different degrees depending on the political system).

That statement amazes me. Iran, formally known as Persia has a rich history of well over 7000 years. Don't believe me check, it out? http://en.wikipedia.org/wiki/History_of_Iran Persia was the 1st nation by far to ever have a recognisable bill of human rights and the UN has acknowledged this since the 70s. (Sorry for the rant, but this is partly because of my disgust at how Persia was portrayed in the film 300) You really need to stop seeing the world so back and white...

Thanks for your reply. Once again I think I am starting to understand this, just like I did with your previous explanation. I am guessing now that when you allow for a dynamical spacetime then things like a light ray not catching up with a galaxy could occur, am I right in such an ssumption? Also when we speak of "dynamic spacetime" does that basically mean not "flat" everywhere, as you said is the case everywhere, or do you also mean changing with respect to time(man, this gets puzzling sometimes!)? It may take me a lttle time t grapple with the ideas, but the learning process is simmering away regardless... I guess that is what this forum fulfills its task for me at the moment is that I can come with conceptual questions from my field of study and yield useful answers to them. I thank you for partaking in this continuing endeavour.(sorry if that was a bit melodramatic:embarass: )

You've lost me with this... You're saying the main postulate of special relativity does not necessarily apply to things that are not "local"? Why is that? I didn't think GR refuted SR, I thought it was an extension to cover the things SR did not(like accelerating frames).

Thx, this is starting to make sense, especially the comment on electromagnetism...tho an understanding of GR is still years beyond me I feel. I will get there tho. Actually, I dont even fully understand SR yet.

I have a query related to the subject of this thread. Considering the fact that that the Universe is expanding at an accelerating rate(also is the the acceleration increasing too?), when working out the age of the Universe do relativistic corrections have to be made, because we have been in the process of being separated from other parts of the Universe at different rates throughout the Universe's "history"? Or is it ok because from our perspective we are in a "proper time"? Finally do the rules of GR still apply even if there is a rate of change of acceleration or a change in that etc etc etc?

Is this true? Energy is a source of gravity? So when Light is bent round, or cannot escape a black hole it experiences a mutual attraction with te black hole because it has energy? I thought this was rather due to the effects of the black hole curving spacetime. You are most certainly right about relativistic mass, lphotons have no rest mass, so they cannot have a relativistic mass.

I'm sorry if this sounds clumsy, but I think a lot of JohnF's difficulties can be overcome if this is thought about carefully with a useful analogous relation to ordinary euclidian geometry. The importan lesson of relativity is that inspite of the time and space between events is relative to a frame in which they are measured, BUT; The spacetime interval between 2 events remains invariant regardless of the frame. The notion that time is a dimension is a useful one, but needs careful geometric definition I feel. For example the invariant we commonly see in Euclidian geometry between our 3 dimensions is: l^2=(dx)^2+(dy)^2+(dz)^2 Here are our invariant interval is l^2 or l, as it doesnt matter what orientation our x,y and z coordiantes are, our interval remains constant. For example imagine I rotated the axes, the distance between 2 points remains constant. If we extend this notion of invariance to what can be called "spacetime geometry" we end up with a different equation(I have included just one length dimension for simplicity, but extension is easy) and invariance: s^2=(c^2)(dt^2)-(dx)^2 Similiarly here, what I referred to as "rotating my axes", in Euclidian geometry, would be changing the frame of reference with which I viewed events, and hence their velocity relative to me. By applying a similiar notion of invariance, we can see here that time plays a role of a "dimension" within this geometry. It is important to recognise however that this is not a direct analogy from what we normally think of as dimensions, aka, the ones from Euclidian geometry. I think this is an important mathematical subtlety that often is omitted in discussions about the "dimensionality" of time. I hope that helps, and I am sorry to any experts if I have stumbled ad made errors in my attempt at an explanation.

Wouldn't there be a slight problem with health concerned with the level of toxins consumed? These tend to increase as you go up the food chain, the level of toxins increases, and so perhaps for that reason human meat would not be that healthy....unles you're eating vegetarians:D. I suppose it woul depend on the conditions of the entire ecosystem inhabited by whatever organism you are about to consume.

It's intriguing you say this, as I had suspected such a link as relatively recently I have taken a module in my course where we studied Chaos and Nonlinear systems. In fact I think it inspired this idea. The logistic map already has application in physics and applied mathematics. I guess I was also wondering if this specific function or something similiar could find itself in physical application. It would be intriguing if this were to be the case. Also I was wondering, probably erroneously though, that If a the phase plot of this function was plotted, then if we looked at the path the function takes from a certain starting value as we increase the value of n, we could observe perhaps "half" functions of tan or fractional functions of tanif we looked at the values produced between discrete integer values of n. I do feel this specific idea is slightly dubious though, and so I am not uite sure of its logical consistency. Again I would like to reiterate, could someone please try producing a plot of this?

Recently I had an idea of a function that I was interested in plotting after playing with my calculator. For some reason I feel it may have interesting properties and as it is based on the trigonometric funtion tan... it could be interesting extending it and start applying it to other geometric functions or series. Anyway, I will introduce my idea: Say you have f(x)=tan(x). Now, once you have a result you take the tan of your answer. Therefore you have; f(f(x))=tan(f(x)). This could then be continued and the "order" n of the function would be the independent variable. The order of the function above for example would be n=2, and for the one above it; 1. What I have been wanting to do is to make a plot of this function with a range of "starting point" values of x on the conventional vertical axis of the graph, and on the horizontal axis to have it plotted against the order n. The results then could be displayed for each starting point and a rough "path" if any of the starting points yield patterns that appear to be continuous. This could be visually amplified by using a graph with shortened divisions between the integer values of the order n on the horizontal axis. Basically, I am wondering if this function will display any intersting properties, and what special areas and starting points there are. I can already make an educated guess that there will be values towards which the results of the function may tend towards. Also there will be some that do not change, e.g. if you start at 0, u stay at zero, no matter what the order is. I have tried, but do not know how to display this kind of plot using the software available to me(Mathcad), so I would be very grateful if someone could please try and do this this and tell me what they observe. I would be even more grateful if a plot could be posted on this thread. Finally I would like to ask; is this idea original? If not could you direct me to more information about these types of functions. The operation, as I have already stated, could easily be extended, and the properties discovered could be interesting. So what do you guys think having read that?

I must say I am slightly dissapointed. This thread has had 22 views, and 0 comments.... Does no one have anything to say anything on this matter, or is the title just not very exciting?

Sorry if I'm being hopelessly ignorant here, but; couldn't the gamma function be used and adapted to solve this problem? The answer would still be ridiculous tho.... EDIT: Atheist, I'm sure you know this but 24! is not avagadro's constant, sry if thats pedantic...

Hi everybody. I would like to share with you something I have been mulling over on and off for the past few months. I remember during lectures when discussing temperature, I was intrigued to ask my lecturer if there was relationship between temperature and disorder. He gave me an answer bt I would be interestedto know how ppl on this forum would answer this question. I now that our idea of temperature only has sensible meaning when applied to randomly disordered enviroments, such as the a volume of gas. I remember he mentioned such a thing as a "cold beam" of particles, with a considerable energy but very low temperature due to the "order" within the beam. Another useful question would be to consider what do we mean by order? I have a few ideas of my own, but I will leave this question open for the moment as I am interested in how you would interpret this. I also know the concept of "heat" has a very important bearing in relation to Temperature, and we see that the amount of energy that is converted to heat increases woth every thermodynamic interaction, in accordance with the 2nd law of thermodynamics. I would think that this concept, has a lot to do with what I have mentioned above, and is perhaps integral to the relation between temperature and disorder. I guess we have to be careful with words as Temperature is only given its usual definition in relation to large macroscopic systems, in which this notion of disorder can usually be taken for granted, allowing us to deal with the phenomenon covered statistically.(Also these "ordered scenarios" would just be isolated occurences within the pool of this larger classically thermodynamic closed system aka the Universe) Finally, this leads me to my final question; Are there other notions of temperature applicable to microscopic or higly ordered pheomena, and do you perceive a need for these?

Quite frankly, this paragraph baffles me. The source which you describe I assume would be the centre of mass of the Earth in the scenario I stated, but then you talked about the radiation being thermal. Why would it matter whether Ultraviolet, microwave or whatever? The type of radiation, if emitted would just reveal to us the level of acceleration of the charged particle. But then this would go agains our principle of relativity! This is because in such a scenario we would be able to detect absolute motion, as we would know the charged particle was accelerating and not us. By relativity, both frames should be indistinguishable, aka you accelerate from me I accelerate from you. Thereby such radiation should not be allowed to occur, but this raises the question; what does happen in this scenario?

Hello everybody:-) . It's been a long time since I posted here, but I think now I may have some more interesting things to come back and discuss now, and with a SLIGHTLY better sense of understanding, or if not that, at least familiarity with the concepts which I tend to discuss on these forums. Anyway, I remember one of my professors mentioning a relatively simple scenario, that was once a paradox in theoretical physics but was resolved, yet it defies me how. I know that the subject matter concerned is electrodynamics, mechanics(as the title may suggest) and general relativity. Anyway! Finally to cut to the chase; We have the often heard "I drill a hole through the Earth"(the length of the hole being the diameter of the Earth) and drop a charged particle into the hole. In the subsequent motion we can imagine the particle accelerating, but doesn't that mean that it should also start emitting EM radiation, and so causing a kind of "drag" on the particle as not all the GPE is converted to KE? If so we can imagine this causing the particle to stop oscillating, and eventually occupy the centre of the Earth. But can this necessarily happen at all, I think I remember my Professor mentioning something about the equivalence of accelerating frames of General Relativity(but I feel am tredding on water here, and may have misquoted him). Therefore the particle would have to keep oscillating, but then if it still emitted EM radiation then this would go against the conservation of energy. Can this "paradox" be resolved, and if so how? Or is it not even a paradox, and have I missed something?

Hi again everybody, I'm glad to say I've finally come to a decision and I'm now studying theoretical physics. I feel it was the right decision, and I have to now catch up on the first few weeks work:-p ! I thank everybody for contributing to this thread, I have been thinking this over a lot in my head, even months before I started my course in chemical engineering. I feel happy now though, I think I am better suited to this course:-) .

Thanks for your posts everybody, I appreciate it. I will take into account what you said about the employment prospects of theoretical physicists Martin, even if it's in the US. I guess I just feel I'm not being challenged in chemeng at the moment, but I suppose its just been 3 weeks. The maths we've been doing so far seems to be pretty bog standard A level stuff. I think theoretical physics would be more challenging in this respect, and I would learn about things that I have been interested in for a little while now. I suppose Chemical Engineering may be more relevant and applicable to society today. I guess my degree will get more challenging and interesting with time. Some of the basic first year modules are boring the hell out of me at the moment though, for example: Properties and application of materials Chemistry for Engineers Design and Proffessional skills(not as bad, but still pretty boring at the moment) The ones I am enjoying are: Fluid flow, thermodynamics and Heat transfer Modelling concepts and tools(the mathsy one) I do not have a problem with the lecturers, and the department of chemeng at the University of Birmingham(which is where I am at) is currently ranked 2nd in the guardian newspaper out of all chem eng departments in the country, and 3rd in the times rankings., I guess just more than a year after applying for this course I'm left wondering if my interests have changed and no longer lie here. I used to enjoy chemistry, but now I find it bores me a lot, for example. I've been thinking over the last few days, it seems I'm picking between an interesting career as a chemical engineer(some parts of the course I have no interest in tho), or a course which I at least think I would find a lot more interesting(theoretical physics). I take your pint too tho insane, it may seem fun at the outset, but I suppose once I switch, I cant switch back, and my thoughts may differ in a year or 2. I suppose I could study aspects of physics or maths that I dont need for chem eng in my spare time, if I wanted as a hobby. Also, I am absolutely sure that we are not taught any Quantum chemistry or anything about lasers on the course I am doing.