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u/Lee_Sins_Left_Nip 1d ago
7 summations is pretty goofy lol
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u/Silent-Selection8161 1d ago
7 Summations sounds like a math focused novelty metal band
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u/metatron7471 20h ago edited 11h ago
Or satanic cult :D like: on the seventh day, the seventh seal to hell shall be broken ;)
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u/MakingPlansForSmeagl 12h ago
See the Seven Summations shatter the seven seals to summon Satan this Saturday saturday saturday....
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u/TraditionalBandit 1d ago
Haha I recognized this page instantly, I remember my Prof going "this page alone is enough to make anyone want to quit physics" in class.
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u/Substantial-Bear6299 1d ago
It’s funny because you will have soon forgotten more math than most people learn in their entire lives. 🤣
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u/node-342 1d ago
What gets me is that there's only one numbered equation on this page. #470, in Chapter Three. How LONG is this chapter?
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u/specialsymbol 1d ago
Which book is this? I want it.
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u/ken_zeppelin Graduate 1d ago
Sakurai's Modern Quantum Mechanics (Third Edition). Pretty much the de facto graduate-level QM textbook.
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u/siupa Particle physics 1d ago
Pretty much the de facto graduate-level QM textbook
Weinberg, Townsend, Shankar?
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u/csappenf 20h ago
Weinberg would just skip most of the computations and expect you to do them in your head as you read along. That's a real grad level textbook. Here's some physics, kids, have fun. Hope you can do the math.
I have no idea why it isn't used more often. Grad school is meant to be a place of suffering. And there's a lot of physics in Weinberg's little book. It's not a bad book at all.
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u/EroniusJoe 1d ago
So now I'm rollin' down Rodeo with a shotgun. These people ain't seen a brown skinned man since their grandparents bought one... Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ... and now I'm rollin' down Rodeo with a shotgun!
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u/ThisOpinionIsWrong 1d ago
Reminds me of when old operating systems would lag and the cursor would multiply itself as you dragged it across the screen.
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u/fkbaganoff 1d ago
I think it’s the same reaction as when you see a guy hit in the nuts and you give an involuntary laugh. It’s the shared pain coupled with better you than me.
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u/GodRishUniverse 1d ago
I personally like using more sigmas early on and then condensing but this person. Some people find it more clearer (imo) but here it seems like a mess
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u/Aranka_Szeretlek Chemical physics 1d ago
I mean, its not your call to increase the sigmas when you combine tensors
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u/Optimal-Savings-4505 23h ago
Oh for crying out loud, why won't they use linear algebra already. All those sums may as well be implicit.
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u/RecognitionSweet8294 1d ago
what book is this?
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u/ihateagriculture 18h ago
Modern Quantum Mechanics by JJ Sakurai third edition, it’s the required text for my QM course this year.
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u/Oh_its_that_asshole 1d ago
God damn physicists aren't going to convince me that isn't a page of magical runes for summoning demons.
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u/YorakHant 22h ago
I once encounterrd something siniliar and just wrote an eftra wide Sigma with all of the summation variables listed underneath. Looked even goofier.
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u/West_Competition_871 20h ago
Randomly came upon this post and I am so glad I'm not learning physics
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u/Magmatt7 19h ago
As a non-physicist that lack mathematical skills to decipher this, this page makes me go:
EEEEEEEEEEEEEEEEEEEE
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u/thriveth 18h ago
Ah, good old Sakurai. Recognize it immediately. Posts like this should come with a trigger warning...
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u/PinusContorta58 Quantum field theory 11h ago
Typical graduate physics book proof be like: It is straightforward to show that (followed by 402483 indices tensor, with 32 sums or integrals)
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u/FlimFlamBingBang 1d ago
Sooo glad I became an experimental physicist… and then switched into machine learning and other cool stuff.
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u/Not-Too-Fat 1d ago
dude im going to study physics at uni in a month is this what physics is because wtf bro
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u/frogjg2003 Nuclear physics 1d ago
This is a graduate level book. It looks hard, but it's really just basic algebra on some special objects. All that's happening here is rearranging some indices and applying some formulas from earlier in the book to expand and then reduce these formulas. If you've done proofs in trig or calculus, it's easier than that.
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u/ihateagriculture 18h ago
Most of graduate level physics involves more fun math than just repeating summations (such as the tensor product of an integral of a repeated product of a summation of something etc.), but yeah this is from the required for my QM course this semester in grad school.
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u/DaDanDans 23h ago
what the sigma what the sigma what the sigma what the sigma what the sigma what the sigma what the sigma
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u/RedditsAdoptedSon 20h ago
i never passed algebra but i just wishhhh i could get to a point where stuff like this makes a lick of sense
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u/Substantial-Taro-533 12h ago
Sakurai’s book was a nightmare. I know it’s not that better but I have really loved the more precise approach taken my Cohen.
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u/dearbokeh 9h ago
It makes me want to cry.
People who don’t know what it is would just see ‘eeeeeee’, which is also what people who know what it says may feel.
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u/slappythejedi 9h ago
i started laughing at the page then saw the name of the post lol
as an aside i read in a novel today a character said they did mathematics instead of physics because physics was easier and i was like oh spoken like an english major
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u/RoyalChallengers 9h ago
İf every summation is a for loop, no one ever would be using this algo coz of complexity
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u/tlmbot Computational physics 8h ago edited 8h ago
All it's missing is the classic:
"it is easy to show"
...proceeds to show something that gives me nightmares of my own inadequacy for the next 6 months to a year
(recognizing this is kind of a bad example since... I think (but haven't really looked, so I am quite happy to be corrected to hell) that we are just looking at a use case for the better notation which is ubiquitous. Maybe this is just a motivation/introduction page?)
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u/Heart_Is_Valuable 6h ago
I can't believe nobody has made this comment, so I'll do it.
Sigma notation go BRRRRRRRRR
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u/Existing_Tomorrow687 1d ago
Haha, I can see how the dense math might tickle your funny bone—those endless symbols and subscripts can feel like a cosmic joke! It’s a proof from tensor theory, specifically about combining spherical tensors using Clebsch-Gordan coefficients. Maybe it’s the absurdity of turning abstract math into a "laugh-out-loud" moment that’s getting you!
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u/DonnaHarridan 1d ago
Hi chat gpt
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u/Heretic112 Statistical and nonlinear physics 1d ago
This is why summation notation was invented lol