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Teoita
Italy12248 Posts
On January 24 2012 23:28 rei wrote: WTF i want to see some of these shit storm, Give us and example so we can all feel stupid together. Solve Shroedinger's equation for a particle in an infinite well of potential, with a Dirac delta of potential that can be put anywhere in the box. H=p^2/2m+v(x)+g*delta(x-a), where v(x) = 0 for 0 | ||
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rei
United States3594 Posts
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Latedi
Sweden1027 Posts
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SeaSwift
Scotland4486 Posts
On January 24 2012 23:45 rei wrote: what's H and what's p what's m and what's g and delta and what's x and a??? g is gravity? p=potential? power? v(x) is vector of particle x? what is this shit? what's a dirac delta of potential? and whos Shroedinger why did he have to come up with this equation? The only friend he had was this cat he kept trying to kill, so he tried to pass the time by doing maths instead. | ||
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Teoita
Italy12248 Posts
On January 24 2012 23:47 Latedi wrote: I thought I wanted to study physics but now I'm sad ;_; Good luck dude It's actually awesome and interesting and amazing...just fucking hard sometimes. And thanks, i will need LOTS of luck | ||
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~ava
Canada379 Posts
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OpticalShot
Canada6330 Posts
So yeah... just study it over and over, and write down whatever comes to your mind on paper... | ||
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SeaSwift
Scotland4486 Posts
On January 25 2012 00:01 ~ava wrote: I got my physics degree but couldn't pass again if I tried. And yes, it's unfair but not unexpected that the math is ridiculous. You're supposed to be learning independently at this point and spending your free time solving as many math problems as possible. Why we do this to ourselves or why any of us choose to be physicists considering the low pay... I'll never know. For science! | ||
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Keyboard Warrior
United States1178 Posts
Add one more to the many mysteries of life, and GL  | ||
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surfinbird1
Germany999 Posts
On January 24 2012 23:39 Teoita wrote: Solve Shroedinger's equation for a particle in an infinite well of potential, with a Dirac delta of potential that can be put anywhere in the box. H=p^2/2m+v(x)+g*delta(x-a), where v(x) = 0 for 0<x<a, infninity anywhere else. g is a constant. I am certainly no genius of any description but this exercise seems pretty standard to me. Delta potentials are almost obligatory. I remember having single and double Delta potentials on the exercise sheets, didn't you have that? What part of the math involved is giving you a headache? I mean, Hilbert spaces and all that stuff is pretty abstract but for most of the calculations you don't need an indepth knowledge of Functional Analysis, just skip it. | ||
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Ssin
United States88 Posts
On January 25 2012 00:39 surfinbird1 wrote: I am certainly no genius of any description but this exercise seems pretty standard to me. Delta potentials are almost obligatory. I remember having single and double Delta potentials on the exercise sheets, didn't you have that? What part of the math involved is giving you a headache? I mean, Hilbert spaces and all that stuff is pretty abstract but for most of the calculations you don't need an indepth knowledge of Functional Analysis, just skip it. Yeap pretty much this. It gets really interesting when you have an infinite series of Dirac potentials (simulates a Crystalline structure). Though the solution that it spits out is also a series, it can get pretty difficult. For this you pretty much just solve as normal taking special care of matching the boundary conditions on either side of the Dirac potential. You need to integrate across the boundary to eliminate the Dirac and get something useable. | ||
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Oldfool
Australia394 Posts
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Teoita
Italy12248 Posts
On January 25 2012 00:39 surfinbird1 wrote:
Show nested quote + I am certainly no genius of any description but this exercise seems pretty standard to me. Delta potentials are almost obligatory. I remember having single and double Delta potentials on the exercise sheets, didn't you have that? What part of the math involved is giving you a headache? I mean, Hilbert spaces and all that stuff is pretty abstract but for most of the calculations you don't need an indepth knowledge of Functional Analysis, just skip it. It's pretty messy if the delta can be put where you damn well please inside the potential well. If it's in the middle then the even eigenfunctions are untouched and the odd ones get a phase because the first derivative is not continous (if i recall correctly, i did this 6 months ago). If it's anywhere in the well, calculating the exact eigenfunctions is annoying as hell. The fun part is when i have to calculate the Laplace operator for an n-dimensional space in spherical coordinates. Why would you even ask such a thing is beyond me... | ||
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mrGRAPE
Singapore293 Posts
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Servius_Fulvius
United States947 Posts
On January 24 2012 22:03 Teoita wrote: Plenty of completely insane math steps that NONE has ever taught me, in ANY class i have taken so far, wierd assumptions and tricks that you NEED to know to keep any kind of mental sanity...it's like, every problem is it's own insane shitstorm with a random trick to avoid insane shit, and every time the trick is different, makes no sense, and assumes math i don't know. This is exactly how I felt about a year ago! I was a first year grad student (engineering) and came from an undergrad program that did not adequately prepare me. There were a lot of tricks that completely bowled me over. I managed to catch myself up, but not in time to save my grades. I needed a 3.2 to remain in the PhD program and I earned a 3.17. But that's ok. I learned more in those 9 months than most of my classmates did. Now I'm a second year masters student who is slowly picking up the tips and tricks that I should know in the future. Overall, it's positive that you don't know or understand something. This gives you a lot of room for growth. This is WHY you're in school! This stuff is hard, but try and keep your head up and do your best. | ||
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Psychobabas
2531 Posts
notices the word "physics" runs the fuck away never looks back!* | ||
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KillerDucky
United States498 Posts
There's nothing worse than trying to follow a mathematical procedure where they assume you know how to do a certain technique and just say "using blah blah technique, equations (1) and (2) obviously lead to equation (3)". I had this happen when I was reading a paper and trying to apply it to a different situation. Even after reading about the technique they used on Wikipedia (obv, where else? hah!), I gave up on it 3-4 times before a couple weeks later I tried again and finally got it. | ||
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surfinbird1
Germany999 Posts
On January 25 2012 00:48 Teoita wrote: It's pretty messy if the delta can be put where you damn well please inside the potential well. If it's in the middle then the even eigenfunctions are untouched and the odd ones get a phase because the first derivative is not continous (if i recall correctly, i did this 6 months ago). If it's anywhere in the well, calculating the exact eigenfunctions is annoying as hell. The fun part is when i have to calculate the Laplace operator for an n-dimensional space in spherical coordinates. Why would you even ask such a thing is beyond me... It's true, Delta distributions are no fun sometimes  And the Laplace oprator in n-dimensions is indeed quite mysterious. I have never come across that. Especially in an introduction to QM it seems totally out of place. I remember QM as the lecture in theoretical physics where it made click for me. Just keep on pushing, man. QM can be a ton of fun, actually. Good luck. | ||
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InternalSync
176 Posts
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Jedclark
United Kingdom903 Posts
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