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Topic Review (Newest First)
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| May 14th, 2006 10:09 PM | |
| Fathom Zero |
From my heart and from my hand, Why don't people understand? My intentions... |
| May 12th, 2006 08:33 PM | |
| Deadsy |
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| May 12th, 2006 07:21 PM | |
| Sethomas |
HOLY SHIT  http://theory.uchicago.edu/~sethi/Te...20S2006/p1.pdf That's a homework assignment for a string theory class taught by my first college physics professor. |
| May 10th, 2006 03:00 PM | |
| kahljorn |
heh, yea I've actually heard of of schrodinger before and I've read various parts of both of Briane Green's books, i just didn't really like his writing style I guess. I might get a book, or I could try to find something online. I don't know, I'm pretty poor at the moment. Thanks for the writing, though, I'll try to get back to you in more detail later- I might look it up online. |
| May 10th, 2006 06:38 AM | |
| Sethomas |
Well, you probably already know this, but I'll offer as a warning anyways my understanding of what "quantum mechanics" means. To me, anything that can be explained in straight-forward mathematical expressions that can be solved with a few months of calculus or less is just "quantum physics". This generally refers to the conclusions derived by Schrödinger after spending a few weeks purportedly in moutain solitude, namely his bastard of an equation. I guess I should note that the equations for Heisenberg's Uncertainty and Quantum Barrier Tunneling, which were derived from the Schrödinger Equation, only use high school algebra and are actually quite fun to solve for storybook problems. However, the Schrödinger Equation is something that I can look at and understand what it does and what is going on, but to actually put numbers into it and thereby arrive at different numbers is something that I really dislike doing and properly speaking have never done properly. The process of actually working with the Schrödinger Equation in real-world problems almost always uses mathematical operators I'm not familiar with, nor with which I desire to be familiar. Quantum Mechanics is thus a very nasty thing to work with, but it's fun to study from second-hand sources for wacky implications. The truth is that most of the weirdness issues with quantum mechanics, such as its incompatibility with general relativity and non-locality, are something that most physics students don't formally encounter until grad school, if at all. However, you can pick up a book of pop physics in the appropriate section of your local Barnes and Noble or whatever and learn about the weirdness with few (if any) numbers or equations presented in a meaningful sense. That's really how I did it for the most part, as much as I try to put up an air of formality and shit. I personally recommend both of Brian Greene's books. In The Elegant Universe, he focuses mostly on M-theory and its progenitors, but does include relativity and quantum physics/mechanics in his outline of physics history and sporadically elsewhere for direction of where certain aspects of string theory is relevant. He deals with both much more in his later work, The Fabric of the Cosmos, which is less a pitch for M-theory (which it still copiously is) than it is a history of explaining fundamental world observations in terms of weird physics. The problem with both of these is that while they impart a good telling of what quantum and relatavistic physics actually mean, they say very little of why. Even his endnotes are little more than teasers; they generally depict pure equations and particle trait tables with no explanation of their derivations. He even presents Maxwell's Equations only in differential terms (as opposed to the more accessible integral forms), leading even advanced students wondering what the fuck is up with the upside-down triangles and shit. One of my physics profs once said in a lecture after I asked him his thoughts on Brian Greene (whom he'd actually met) that he's "too turtle-necked black sweater-type" for his taste, or something to that effect. (Greene probably gets that a lot, because in FOTC he tries way too hard to relate to the slobbering millions with his countless appeals to Bart and Lisa performing experiments on skateboards going relativistic speeds.) Later in a study session in his office, a fellow student asked if there was any remedy to the probabalistic nature of quantum mechanics and I threw in that string theory might do that eventually. His retort was that it's arguable whether or not string theory constitutes real physics, as it's just mathematical formulae that make no falsifiable conclusions and are probably better termed as "abstract mathematical philosophy". That professor did have otherwise a very weird sense of humor of deliberately transparent condescension and was a generally swell fellow, so don't take that to mean he's just a jerk (even though he didn't accept my late homework :angry). Example: he used his wristwatch to disprove the Bohr model of the atom by counting down the time for electrons to collapse on their nuclei and cause the class to cease to exist: it was something like a billionth of a second. HOWEVER: if you feel up to it, I do sincerely recommend that you get an undergraduate physics textbook on the subject of "modern physics". Once they are replaced by more current editions (with the differences usually only being the numbers in story problems), these books generally run VERY CHEAP on Amazon Marketplace being sold by desperate college students. This will give you an earnest explanation of why the equations say what they do, and in most all cases the equations themselves. Generally special relativity is covered in full, as it involves only high school algebra, and esoteric operators are either prefaced with explanations or are omitted entirely. General relativity is grounded in linear algebra, so either expect its equations to not be included or not be able to understand them if they are. Quantum physics is usually explained very clearly with actual equations and their derivations, but beyond Schrödinger these become useless to real impact. Expect to deal with quantization of atoms and such, which isn't as intimidating as it sounds. Woo. |
| May 10th, 2006 05:07 AM | |
| kahljorn | Do you know anything worth reading on quantum mechanics? I don't really know all that much about it. |
| May 10th, 2006 03:37 AM | |
| Sethomas | Yeah, Bell's Theorem is actually the description of the paradox of quantum mechanics as it involves non-locality, as Bell popularized paying attention to it although Einstein and some collaborators had pointed it out decades earlier. Experiments that confirm (or deny, I guess) it usually have Bell somewhere in the title. |
| May 10th, 2006 03:12 AM | |
| kahljorn |
"quantum mechanics dictates that acting on one particle at point A can affect the behavior of a particle at distant point B instantaneously." Reminds me of what I remember as bell's theorem. At the very least, they are a very similar theory. |
| May 10th, 2006 01:23 AM | |
| Sethomas |
Weird science makes me hate everything, including you. I've been avoiding this forum as of late because it's so depressing, and I don't need that. Between posting on the other forums and leaving my room for fast food twice a day, I've been devoting my life to conquering wikipedia. After describing M-theory to a friend a while ago, and then seeing a reference to a scav item I turned down demanding, "explain string theory using only sock puppets", I decided to refresh my understanding on the subject. Naturally, wikipedia was the first source. I was first reminded of the principle of non-locality, which is something that royally pissed me off when I first learned of it in 2004. Enough had happened in the following months that I was able to be royally pissed off at other facets of reality (exemplia gratia, my life), so it was more or less erased from my daily recurring thoughts. Then today, I read more about it and all those memories came back. Basically, as I remember it descriptions of experiments I read in 2004, quantum mechanics dictates that acting on one particle at point A can affect the behavior of a particle at distant point B instantaneously. Communication between the two is possible because even if there were a "messenger particle"* causing it, it would necessitate hyper-luminous speeds and not really solve any problems. So, basically, reality makes NO SENSE WHATSOEVER. As far as I know, non-locality is just a weird implication of quantum mechanics that has been verified to be true in experiment. However, nobody understands how it actually happens, only why. I'm too inept to solve it myself, and I doubt anyone else will in the foreseeable future. Why was I born into a time where the problem was known but the solution beyond grasp, without the means of doing anything about it except get pissed off? Fuck you, physics, for showing us these quirks of existence. And fuck you, existence, for being so quirky. *The term "messenger particle" just seemed the most apt to convey what I meant, but the term proper already refers to those particles that result in the four forces of nature (photons, gravitons, yadda yadda). |
