timo

What´s an "apoapsis"? And as a follow-up question: What´s a "periapsis" ?

I can only speak for me, here. But I get much less headaches from the idea of describing a vector with a linear combination of base vectors than from particles being in two states simultaneously. I also wouldn´t have commented on "superposition of states" . But "is in both states" strictly speaking means "|dead> = |state> = |alive>" while superposition correctly sais "|state> = a|dead> + b|alive>". As said, this might seem a bit pedantic. But I feel that the distinction between being in a certain state or having a non-vanishing projection on that state can be crucial for understanding QM (though, I wouldn´t know a good example atm). That´s true of course. But in this case the statement doesn´t really seem to apply as from his profile Bobby actually is going to spend (or allready did spend) some years learning QM. Of course, you could say "go to your classes or read a book instead of asking here" but this attitude would imho reduce this forum to posts about the morals of atheists and ways to disprove relativity. Providing someone with incorrect ideas, regardless wheter this was because of an incorrect statement or a correct statement that was misinterpreted, can severely reduce the effectivity of learning physics if the person sticks to them too hard. E.g. I read somewhere that in QFT you replace the states with theit creation and annhilation operators. For several years I was completely unable to see the point in QFT or to even make any sense of it (how can QM without states work?). Then, not too long ago, I read a paper that explicitely described how to obtain the S-matrix by pulling out particles of the inital and the final state, leaving the vaccuum state (so there still are states in QFT!) by using these operators. At this point it made "click" and I suddenly understood a lot of what made absolutely no sense to me before. And the main hindrance for understanding QFT was that "replace the fields by their operators" statement which isn´t even incorrect if you know what´s meant.

Strictly speaking you are both wrong. A quantum mechanical system allways is in a single definite state. The state just isn´t nessecarily an eigenstate to the observable you are going to measure. This is what leads to the unpredictability of the measuring process (which I did not fully understand up to today) because a QM axiom claims that after the measurement the system will be in an eigenstate to the eigenvalue maesured. But the system still is in a single definite state at any time. This may sound pedantic but I feel that this "the system is in multiple states at once"-thinking is one of the biggest hindrances for understanding QM - you can only understand such statements if you know that you have to interpret "it is in both states" as "its state is non-perpedicular to both states". Not that I´m saying you don´t know what you were saying. I just wouldn´t understand your statements correctly if I didn´t know QM. EDIT: I found a quote from the original paper on the german version of wikipedia. Seems like Schroedinger introduced this though experiment to show that QM effects which usually are important at very small size-scales (and therefore leave you with the "you can´t see it anyways"-excuse if something doesn´t seem to make sense) can be transferred to macroscopic, easily observable systems. It seems that he did this to show that QM makes absurd predictions (the cat being neither dead not alive unless the box is opened). As the example seems to be chosen to show the absurdity of QM, there´s not much learning effect to be expected from it.

Python is just fine for a start. It´s easy to use (it´s more or less like basic) and powerfull enough to even write advanced programs with it (unless performance is a real issue, but the bottleneck usually is the programmer, not the language used). And most importantly it´s an interpreter language which allows you to test things (and you´ll need to do a lot of testing even on small things like "what´s the result of a*b for vectors a and b" whenever you learn a new language) in command-line mode. So you don´t need to write an executable to test this like you have to do in C. On the other hand, programming languages (those I know at least) do not differ much anyways. They are just a tool to write programs. The "real" programming is done in your head or on a piece of paper (using some pseudo-code), anyways. So the question which programming language to chose is a bit like asking which language learn to become a journalist. If you´re really going to use Python: It´s some time since I last used it but I remember that I liked the "SciPy" (scientific python) package a lot so you might want to check it out. Depends on what you´re going to do, of course.

For QM it is probably sufficient to know that the FT is a base transform in a vector space of functions. Therefore, you should know Linear Algebra if you want to understand what you are doing.

1) Do you know linear algebra? A matrix can be seen as a linear map of a vector space on itself. An Eigenvector is a vector that remains the same under that transformation except for some scaling constant. The same holds true in QM. This time, your vector space is the so-called Hilbert Space, a space of functions. An operator is a map of this function space on itself. An Eigenfunction is a function that is mapped on itself under application of this operator (again: Except for some constant called "Eigenvalue"). 2) The Schroedinger equations is the movement equation for any nonrelativistic quantum mechanical system. Note, however, that the appearing operator H (called the "Hamiltonian") differs from system to system.

You arrange a meeting somewhere in spacetime.

Well, it´s nice that you take the time even quoting a passage of the book for me. But I´m afraid I won´t get it without seeing any kind of familiar formula. I´ll sleep a night about it and maybe ask a few people at work tomorrow.

No, I don´t get the context with the Planck Length. I don´t even understand what that "left and right, ... lose their meaning" is supposed to say.

Watched it but didn´t find any statement on the Planck Length at all. Cool special effects, though. But to come back to my original point: The reason why you end up below the Planck Length is probably because you´re dealing with a mass that has non-neglectible mass when it comes to gravity (whatever neglectible is supposed to be in the macroscopic regime) .

Thx for the link. I think I´ll take a look at the streams when I have the time. Do you know which of the episode the statement is in? Yes, it most certainly has to do with warping of spacetime. As a matter of fact, "gravity becomes strong" simply states that you can´t neglect spacetime warping anymore. I just don´t get the step to "therefore length becomes meaningless". Can´t really see what it would have to do with uncertainty. But on the other hand, uncertainty in position might need a better definition in a warped spacetime. Perhaps that´s where it stems from.

I´ve never understood those "nothing has a meaning above/below the planck <add unit here>"-statements so far - but the only place I´ve encoutered them is in this forum, anyways. To my knowledge the Planck mass is just the energy (yes, I use c=1) where gravitation is estimated to be rougly as strong as the other forces. I´d bet you get the Planck length by multiplying suitable exponents of c and hbar so that the dimension fits. I do not know why this should lead to a statement as "length has no meaning below the Planck length". But I am almost sure that earth´s gravity cannot be neglected.

Is that a question? The answer is in the text: To elaborate more: We had a talk by one of the CERN Higgs people last month (so it´s most probable that he knew the data from 2000). He did not mention any direct experimental evidence found for the Higgs so far, not even hints on it. So I´d consider the "tantalizing evidence for one just at the limits of the collider" the usual "we need more money to build a larger collider" statement. That´s nothing special. I read up some papers on extra neutral gauge bosons some weeks ago. It was interesting how the estimated mass of this additional particle (Z-Prime to be exact) increased with the year the respective article was published. Allways just above the mass range allready ruled out by experiment. Other than that "tantilizing evidence", the article just seems like a review of the Standard Model and Supersymmetry to me. One thing that imho is worth mentioning in this context: Supersymmetry gives an upper bound to the Higgs mass (can´t remember why, atm) at around 140 Gev (I think). This is in a range such that if the Higgs will not be found at the LHC, at least some very promising SUSY theories are ruled out. Of course, I hope that we find the Higgs.

Hey, we have theads like the "Shadows" one in the "Modern/Theoretical Physics" subforum and you are afraid to put a rather good (well, valid, at least) question on QM in the QM section? You don´t even claim that your idea must be true because it came to you when you were completely stoned last night and suddenly recognized how the universe works. I think this definitely is a QM question (as a matter of fact, in can be even seen as a Modern Theoretical Physics question, but see below for that). And even though you seem to lack some basics of QM this thread should still belong there. I´ll send the easiest refutation to your idea ahead before I get into detail: If there was only one electron, the total charge you could have, say on a capacitor, would be 1.6*10^-19 Coulomb. You´d have to scale the wavefunction to the total number of electrons, at least. Another problem would arise from electron-electron interaction. How would you expect two electrons to repel each other if there is only one? It does exists. Many people regard the wavefunction only as a probability function for finding the electron. This is not completely true. The wavefunction IS the electron*. The little point-charge you usually have in mind simply doesn´t exist as such. *Yes, I am aware that the wavefunction is only a description for the electron. But the point of my argument was that the electron (and every other particle) is not what you expect when you come from classical mechanics. Yes, it does. All of them do. I wanted to start from classical QM going over many-particle QM to Quantum Field Theory, here. But while writing it I quickly figured out that putting almost two years of a university Theoretical Physics course in one thread completely overtaxes me. So before I directly jump to QFT I just want to make an additional remark why the "only one electron" idea wont work: Assume you make two precise measurements on the electron´s position. One at t=0 and one at t=T. The first one measures the electron to be at x=0. Due to uncertainty the electron can have any momentum, now. But it´s velocity is still bound to be <c. So for the 2nd measurement you couldn´t measure the electron at any x>cT. In other words: Each time some pixel on your monitor appears, you have stripped the sun of all it´s electrons for a few minutes ... EDIT: As a hint for certain people: Disproving Relativity with this shows much more creativity than the usual I-messed-up-the-coordinate-transformations method. Now for QFT and the reason why I think your thread is actually quite good: In QFT you actually do describe each type of particle by a single field (hence the name). But in contrast to the classical description of an electron as a wavefunction, the total amplitude (squared) does not need to be normalized to one anymore. Also, you don´t kill the sun just because you switch on your monitor, here. But you actually have problems defining what an electron is supposed to be at all, now. The definition of a particle becomes even more dizzy than the "it´s a wavefunction" picture from above. You could call the electron field "the electron", so in this case your assumption that there might be only one electron would be correct. However, this definition of the electron would have little in common with what you´d expect an electron to be. And it´s simply not the common definition. Summary: There must be more than one electron because of the definition of it. Disclaimer: Unlike most of my other posts I am not completely certain of what I am saying here, as I am just beginning to learn QFT myself, atm. So any (competent) corrections are highly welcome.

Not totally different theories, of course. It´s both relativity. But totally different approaches with totally different solutions. In the Black Hole case you have all mass concentrated in a single point in space (perhaps saying "a single trajectory in spacetime" would be better, here). The spacetime solution you get is in fact only valid outside the mass distribution. In consmology you assume the mass to be spread out equally over space (here, the distinction between space and time is valid as cosmology assumes a global time coordinate). This is a completely different approach as you are evaluating the spacetime structure inside the mass distribution, now. Also, you have a time-developement of spacetime (which you can extrapolate to a point where all space-distances approach zero) while in the Black Hole case the spacetime is constant with the time coordinate (at least in Schwarzschild coordinates and outside the event horizont). Yes. for some unkknown stupid reason I am not allowed to edit my posts after a certain time has passed. So even though I also recognized that the crucial word "backwards" was missing I couldn´t edit it anymore. And I didn´t want to make a new post just to correct one missing word.

I think I can give you a few hints on how to achieve that: - Leave your inappropriate "Get serious, please. Is this a debate or a circus?"-arrogance at the login button. - Try to stay on topic (ok, flaming is kind of on-topic in this thread ). Just because you´ve seen spinors in relativistic quantum mechanics doesn´t say it has anything to do with this thread. - If you are adressed by someone, ignore it or give a serious reply. Asking someone to to some mathematical conversions before you consider him relevant enough to bother isn´t appropriate. Especially when the conversion doesn´t make any sense and the equation doesn´t even compute (see next point). - Do have a bit of knowledge about what you are talking about or if not: Admit it at least. - You shouldn´t respect people because they have that "blabla Expert" sign under their names but because they are members of this forum (or in the wider sense: because they are people). About that text you mentioned: Well, I simply didn´t want to read all that crap and parsed to the points that seemed to have physics in it. First interesting point was this:

I don´t think so. The mathematical background is a different one. In the Black Hole (Black Hole + White Hole, if you prefer) scenario you have an infiinite spacetime and a high concentration of mass in one area of it. In the Big Bang scenario you have spacetime shrinking towards a single point with time in the sense that distances between points (events at a given, equal time) approach zero.

"White Holes" are a construct that comes from a mathematical expansion of the Schwarzschild solution (the spacetime of Black Holes). They are in agreement with the Einstein equations. However, no such entity has been observed so far. However, atm I am not sure if the "travelling to a parallel universe" (which has it´s origin in the same mathematical construct) implies that if you enter a Black Hole, you´ll come out of a White Hole on the other end. "Kruskal Coordinates" would be one of the keywords if you want to google for more information (the Kruskal Coordinates are the extension I spoke of).

Since Gravity is usually considered an effect of spacetime warping, I think those two sentences contradict. At least, I don´t get what you were trying to say.

goodidea notusig proper spelling intentionally issimplyrude especiallyinafroum that contains nonnative englishspeakers.

Because the mechanical energy has to go somewhere and thermal energy was my first guess where it might go. You shouldn´t take my post as a very qualified one. It was rather an attempt to bring this discussion on a scientific (=quantitative, in this case) level rather than a "I guess it´s the ..."-one.

If I remember correctly, a wormhole not only requires a spacetime singluarity as it´s created by a black hole (you don´t need a whole big bang for it - a few sun masses will do) but also some matter with exotic properties (negative pressure, positive mass density) to become passable. No such kind of matter is known up to today. As another matter of fact, wormholes are more or less just a mathematical bauble stemming from "hey, we get usefull results of we allow the r-parameter to become negative" (note that the physical meaning of this parameter is associated to distance) . For your "parallel universes are one second away from ours" idea: Both past and future are also considered part of the universe as time is just a coordinate as x,y and z in cosmology. You could as well say the parallel universe is 1m to the right. In my case the parallel universe would be a white wall, then. And transition to parallel universes would become quite easy (ok, not so easy for the wall-case ).

While I didn´t understand rajama´s post, I think I can help you out here: Two particles can have a relative velocity greater than c. If one particle travels to the left with 3/4c and the othe one to the right with 3/4c, then they do have a relative velocity of 6/4c = 1.5c > c. That´s not forbidden by relativity as both have a velocity of < c (for the nitpickers I´d like to explicitely exclude non-observable and non-observed particles here). However: In contrast to nonrelativistic physics and intuition the relative velocity of two particles does not remain the same when switching to a different frame of reference. In fact, the relative velocity will change in such a way that the relative velocity of the particles will allways be <= c in a frame in which one of the particles is at rest. If it wasn´t like that the other particle would have to have a velocity > c which isn´t possible since a velocity <= c in any coordiante system will be <= c in any other (the number which describes whether a particle travels with lightspeed, slower than c or >c is the same in any coordiante system). To sum it up: Relative velocities >c are possible if none of the particles / observes is at rest in the frame of reference the relative velocity is measured in but relative velocity is frame-dependent. Oh, and: Every particle that travels with <c is a valid observer.

While I considered the question dull when I first read it (my 1st guess was: The moon: The sun doesn´t induce tides) it gets more interesting the more I think about it - but that´s of course also due to the vague expression "influence". If you consider the ammount of energy stored in the water I´d bet it´s the sun. The direct heating with sunlight should easily exceed the ammount of heat that´s stored in the water due to the internal friction that occurs due to the water moving because of the moon. If you consider gravitational effects only, then things perhaps aren´t as trivial as they seem. The gravitational force on the water can of course be easily calculated: Sun: F_Sun = dm * M_sun/d_sun² = dm * 332000 / (149,597,870 )² ~= 3*10^5 /2.25*10^16 ~= 10^-11 dm Moon: F_Moon = dm * M_Moon/d_Moon² = dm * 0.01 / (384,400)² ~= 10^-12 dm (distances in km, masses in multiples of earth mass, numbers from http://www.solarviews.com/eng/) The numbers show that the gravitational attraction due to the sun is (didn´t bother to look for a pen or to even use a calculator, so they´re only an approx) 10 times greater than the gravitational attraction due to the moon. Now the question arises: Why does the moon have a visible influence on the water in a sence of tides while the sun hasn't? I see two possible reasons for this: 1) Earth´s rotation. I will not consider this here as this would really force me to grap a pencil . I also do not expect much of it when compared to the factor 200 from 2). 2) If the whole earth was in a constant gravitational potential there wouldn´t be any tides at all since all of earth matter is accelerated by the same ammount. The tides therefore must stem from either 1) or the inhomogenity of the gravitational field which causes objects nearer to the moon/sun to be attracted more than those that are more distant. The inhomogenity can be described (in an approx, of course) by the derivative of the gravitational field with respect to distance. This leads to: I_Sun = d/dr F_Sun = 1/r_sun * F_Sun = 1.5*10^-8 * F_Sun = 1.5*10^-7 * F_Moon I_Moon = d/dr F_Moon = 1/R_Moon * F_Moon = 3*10^-5 * F_Moon This handwaving argumentation therefore assumes the tidal effects of the moon to be 200 times greater than that of the sun even though the force excerted by the sun is 10 times larger than that of the moon. As a note for those who are confused by my math: I´m perfectly aware that I didn´t use SI units or took care of signs here. However, as I´m only talking about ratios here, this doens´t play a role at all. The assumtion that the inhomogenity of the grav field is responsible for the tides is only the first approach to estimating the effects quantitatively that came to my mind so it´s probably far from perfect.

No, it´s just easier to use.