timo

I knew there´s a thread listing the normal user titles somewhere around: http://www.scienceforums.net/forum/showthread.php?t=127&highlight=user+title Titles (or silly descriptions) not in that list are a hint on someone with a custom user title i.e. either admin, moderator or expert.

Two quarks . Next rank is baryon, three quarks, I think.

Tom: Motion stopping in this case indeed means the ratio of coordinate distance to coordinate time dr/dt, not the ratio of coordinate distance to eigentime dr/[math]d\tau[/math]. The particle witnesses itself as falling into the black hole within finite (eigen-)time. I´ve attached a plot below. It only shows the integration of the equation of motion till the event horizont (i.e. the particle doesn´t pass the event horizont) because the calculation used the same "improper coordinates" (Schwarzschild coordinates) as Janus' post above and those coordiantes have a singularity at the event horizont. But it -hopefully clearly- shows that the particle seems to stop in coordinate time, while it seems to simply fall through the event horizont if you describe the fall in eigentime. Attached image: http://www.scienceforums.net/forum/attachment.php?attachmentid=1462&stc=1&d=1167412943 ON THE ORIGINAL TOPIC: The apparent stopping of a particle is usually calculated for an already-formed black hole. Most importantly, the solution you are usually given is the solution for the spacetime geometry outside the mass distribution. During formation of a black hole, the conditions that all mass is inside the event horizont is obviously not met (not for the scope of your question, at least). I am not sure if the spacetime geometry inside the mass distribution would also predict this "particles seem to stop at the event horizont"-effect. Quite on the contrary, I would be pretty surprised if a stone you´d throw into a hole through earth would suddenly come to a stop near the center because it reached the event horizont of earth.

Particles are just parts of a field in a similar sense as a wave (particle) is part of the ocean (field).

No, not for proportionality. y/x=c, cx=y and x/y = 1/c is the same equation (in the sense that it describes the same relationship between x and y) - it´s just written down in different ways. c = x + y is a different equation (you cannot manipulate it into one of the equations above) and none that describes a proportionality between any of the letters involved.

x being proportional to y means that x = c*y with some constant c (which should not depend on y). In words you could call it "x is a multiple of y". EDIT: The statement below might not be correct; I am not sure how common it is to speak of proportionality if c<=0. In fact, this does not even necessarily mean that x gets bigger as y does. If c is negative then in fact the opposite is true (although the magnitude of x will still increase if the magnitude of y does).

I set up a little explanation, there we go: http://www.wisci.org/wiki/Redshift#Gravitational_Redshift .

x ~ y means x = c*y. So proportionality means that one value is a multiple of another. The inverse of multiplication is division. That means that inverse proportionality should be x = c/y. Applying that to your question we see that you´re stoned: From c = x*y => x = c/y. From c = x+y => x = c - y. Both connections of x and y have the property that for an increasing y, x gets smaller. But proportionality and antiproportionality are more than just this rather weak statement. In fact (anti-)proportionality is already a pretty strong statement about the connection between two values x and y. See it this way: You have reduced the huge amount of possible combinations (x,y) to one degree of freedom: c.

You can find interesting stats about SFN. For example that roughly half of the registered members have more than one post

I do not fully understand your question. Are you familiar with the redshift (e.g. could you calculate the redshift occuring when I point a laser pointer towards a satelite) and want to discuss the results or haven´t you seen the math, yet? Imho, redshift can be purely considered an effect of gravitational time dilatation leaving the EM wave (in a suitable coordinate system) basically unchanged but letting the observers do different measurements on it. I´m pretty fu... tired right now so I´ll not elaborate for now. I´ll setup a little explanation of gravitational redshift the next days unless you already know the math.

^^ I can recommend the NeHe OpenGL tutorials. You don´t have to read them in order; try getting the rotating cube to work and then stick your nose in whichever tutorial topic seems interesting and experiment around with it.

[math] \frac{df}{dx} = \frac{d}{dx} \left( (x-1) \cdot (x+2)^{-50} \right) = \left(\frac{d}{dx} (x-1) \right) \cdot (x+2)^{-50} +(x-1)\cdot \left( \frac{d}{dx} (x+2)^{-50} \right) [/math] [math] = 1 (x+2)^{-50} + (x-1) \cdot -50 (x+2)^{-51} = \frac{x+2}{(x+2)^{51}} - 50 \frac{x-1}{(x+2)^{51}} = \frac{52 - 49x}{(x+2)^{51}} [/math] Guess that point goes to your teacher (I did the calc because I thought you might both be wrong). As a (very vague but hopefully helpfull) hint on derivatives: In polynomials, taking the derivative reduces the exponent by one. Here, you have something similar with the factor (x+2)^-50; the denominator. The answer does not necessarily have to look like the (x+2)^-51 which it does, but a jump from -50 to +51 (or +50 to -51 if it´s in the denominator) should be an alarm-sign that something can´t be correct with your solution.

Let´s start with a minimalisitc reply: You should ask yourself whether it was the chicken or the egg that came first. Physics is a natural science meaning it should reflect the behaviour of nature. If a mathematical model properly reflects the behaviour of nature, then it´s egligible to be called a physical model (and therefore a theory of nature).

I´d try this: There is only one degree of freedom you have: The extension of the box in one of the axis-direction (because this extension automatically gives you the other two extensions, at least when you assume that the box touches the ellipsiod, which seems a sensible assumption). Try to express the volume of the box by this one parameter, then find the maximum as usual (by taking the derivative with respect to this parameter). I cannot guarantee you that it works because I haven´t worked it out, but it´s what would be my first attempt.

It might help to know which country you are living in, what type of school you are attending and which class (schoolyear/type of course/...) you are in.

The most obvious property is that they should have the desired distribution. Another property you usually want is that they appear uncorrelated. However, for the latter there is afaik no fixed definition of what that means and several more or less usefull definitions exist. If you just count from one to ten and then start at one again, it´s obvious that the numbers are evenly distributed but hopefully your criterion for non-correlation will tell you that they are correlated. Some time ago I checked some random number generators with a program called DieHard by G. Marsaglia (who also has published a paper on a random number generator and has even published the source iirc). Maybe you can find some criteria he used when looking for it. As far as I can see, there are different algorithms for different bit-sizes of the register. I do not know to what extend these algorithms differ in quality but obviously an algorithm with a lower number of bits can return less different numbes. I am not sure of the step from 32 bit (which allready is 4 (US-)billion possible different numbers) to 64 bit really makes a difference in any application. Using the 32-bit algorithm on a 64-bit machine (by atificially taking 32-bit integers) will return the same values as on a native 32-bit machine, so in this sense the algorithm is independent of hardware.

[math] 2(x-1)^2 +2 = 2x^2 - 4x + 2 +2 = 2x^2 - 4x + 4 \neq 2x^2 - 4x + 6 = y [/math] Evon: You consistently forget factors, e.g. from 2(x² -2x +3)=0 => 2(x² -2x)=-6, not 2(x²-2x)=-3. howareyou: You should try carrying around the "y=" part of the equation all the time. I think it would make things a lot easier for you.

I think it´s only one that´s called fundamental theorem of calculus, the one ajb mentioned.

I almost thought so. I mostly mentioned it because you were saying "that lasts me for years" and I thought a graphics calculator won´t help you much for giving a talk on a conference or stuff like that. I don´t know how important that "lasts for years" is for you and I also don´t want to be the one responsible for your choice (all advice is given without any warranty!) but one thing you shoul possibly keep in mind is the following: Of those who give recomendations for a graphical calculator here, how far beyond 2nd year of physics do you think they are? EDIT:For the sake of fairness I should explicitely say that I´ve never used a graphical calc, so I don´t know what I might be missing - I certainly never missed anything.

I know I am pretty alone with my attitude but since you said "any opinions appreciated" ... I recommend the next-best cheap pocket calculator like my TX-30 solar for calculations done on a piece of paper (smaller calculations, exams, ...) and a small (in the sense of size) laptop with a good battery for more serious work (lab reports, storing data of measurements, talks, theses, ...). CPU speed, memory, graphics card and stuff are pretty secondary there, so the laptop could probably get pretty cheap. I think you can substitute any function of an expensive pocket calculator with an appropriate small freeware program on a laptop. And in addition you get a good way to store and transport data and a platform that you can write papers (publications, theses, internal notes, lab reports, ...) on in addition to that.

Perhaps the postcounter should be clickable showing an explanation. Anyways: 1) Hi 2) The counter counts only posts in the scientific fora. The introduction thread you posted in is in the general discussion section which does not count as a scientific forum. Well, perhaps the "only scientific forums count" is not completely correct - afaik, posts in the politics section are also counted. Anyways, the message is: In some subforums, your posts don´t count towards the postcount. So what you experienced is not a forum bug but the result of a setup the admins have decided upon at some time in the distant past.

I am not sure if I get your question. If you´re asking how valuable something is in a situation where it is worthless, then I guess the answer is "worthless".

Dunno if it´s a mood point for you but plugging the error message into google often helps, e.g. in this case I found http://wiki.x.org/wiki/NVIDIAProprietaryDriver

I don´t think so. But from own experience: In the medical field you have to write and sign a lot of papers, and then some more. My signature has significantly changed even within one year of working in that field. You might extend it to any higher educated ppl (not necessarily more intelligent ppl): The more you advance in school or university, the more often you have to write more information in shorter time. That can cause your handwriting to adopt to it becoming more efficient (on the writing side, not necessarily on the reading one). Just and idea of mine, though. EDIT: Oh, and "I am sooo smart" is a poor excuse for a bad handwriting