corpus.blog
41554 blogs · [ { "id": "01a087d7-433c-7048-8532-def328f7b10a", "title": "Furry's Theorem, Part 1: Why an Odd Number of Photons Can't Come From Nothing", "url": "https://rohankulkarni.me/posts/notes/furrys-theorem-part-1/", "published_at": "2026-07-25T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-53044e1ef159", "title": "Furry's Theorem, Part 2: What It Buys You", "url": "https://rohankulkarni.me/posts/notes/furrys-theorem-part-2/", "published_at": "2026-07-25T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-53044edf75b8", "title": "Self-Energy, 1PI Diagrams, and the Dyson Resummation", "url": "https://rohankulkarni.me/posts/notes/self-energy-dyson-resummation/", "published_at": "2026-05-02T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-53044fb3a5f9", "title": "Why Renormalization Is Needed: The Källén–Lehmann Spectral Representation", "url": "https://rohankulkarni.me/posts/notes/field-strength-renormalization/", "published_at": "2026-05-01T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-5304508dd5c7", "title": "Starting MSc Physics at Heidelberg — What We Wish We Knew Earlier", "url": "https://rohankulkarni.me/posts/blogs/heidelberg_msc_guide/", "published_at": "2026-04-15T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-5304514198a8", "title": "Lie Groups and Lie Algebras, Part IV: The Poincaré Group and the Classification of Particles", "url": "https://rohankulkarni.me/posts/notes/poincare-group/", "published_at": "2026-04-06T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-53045193d8b5", "title": "Lie Groups and Lie Algebras, Part III: Spinors, Fields, and the Representations That Matter", "url": "https://rohankulkarni.me/posts/notes/lorentz-representations/", "published_at": "2026-04-05T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-53045284ddc3", "title": "Lie Groups and Lie Algebras, Part II: The Lorentz Group", "url": "https://rohankulkarni.me/posts/notes/lorentz-group/", "published_at": "2026-04-04T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-53045384db95", "title": "Lie Groups and Lie Algebras, Part I", "url": "https://rohankulkarni.me/posts/notes/lie-groups-lie-algebras/", "published_at": "2026-04-03T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-530453a03239", "title": "Faddeev–Popov Quantization (Abelian), Part 2: The Trick, the Propagator, and What Counts as Gauge Fixing", "url": "https://rohankulkarni.me/posts/notes/faddeev-popov-abelian-part-2/", "published_at": "2026-04-02T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-5304546fb096", "title": "Faddeev–Popov Quantization (Abelian), Part 1: The Overcounting Problem", "url": "https://rohankulkarni.me/posts/notes/faddeev-popov-abelian-part-1/", "published_at": "2026-04-01T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-53045559c1f8", "title": "Dark Energy Beyond Scalars, Part IV: Perturbations, Gauge Invariance, and What Propagates", "url": "https://rohankulkarni.me/posts/notes/dark-energy-p-forms-part4/", "published_at": "2025-12-23T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-5304557a8977", "title": "Dark Energy Beyond Scalars, Part III: The Cosmological Principle Meets Higher-Rank Fields", "url": "https://rohankulkarni.me/posts/notes/dark-energy-p-forms-part3/", "published_at": "2025-12-21T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-5304557e66a8", "title": "Dark Energy Beyond Scalars, Part II: Gauge Symmetry, Mass, and Degrees of Freedom", "url": "https://rohankulkarni.me/posts/notes/dark-energy-p-forms-part2/", "published_at": "2025-12-20T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-530455d894e6", "title": "Dark Energy Beyond Scalars, Part I: Why p-Forms?", "url": "https://rohankulkarni.me/posts/notes/dark-energy-p-forms/", "published_at": "2025-12-19T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-5304566bda10", "title": "Cosmology (Heidelberg, WiSe 24/25)", "url": "https://rohankulkarni.me/posts/teaching/cosmology_heidelberg_wise24-25/", "published_at": "2024-10-15T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-530456927f54", "title": "Bose-Einstein Condensation (1): Can it occur in 1D and 2D?", "url": "https://rohankulkarni.me/posts/notes/bec-1d-2d/", "published_at": "2024-05-24T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-530456e25b79", "title": "IPSP Leipzig Part 3 - Do's and Don'ts for the course", "url": "https://rohankulkarni.me/posts/blogs/ipsp/ipsp3/", "published_at": "2024-05-03T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-53045710c58f", "title": "Classical Mechanics – Best References for Physics Students", "url": "https://rohankulkarni.me/posts/bibliosphere/ug/cm/", "published_at": "2024-04-07T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-5304577c6c9a", "title": "Mandelstam Variables in the CM Frame", "url": "https://rohankulkarni.me/posts/notes/mandelstam-variables/", "published_at": "2024-04-03T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-530457cdb4c8", "title": "Virial Expansion for Hard Spheres", "url": "https://rohankulkarni.me/posts/notes/virial-expansion-hard-spheres/", "published_at": "2024-04-03T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-53045888ee07", "title": "Advanced Quantum Field Theory (Heidelberg, SoSe 2024)", "url": "https://rohankulkarni.me/posts/teaching/qftii_heidelberg_sose2024/qftii_heidelberg_sose24/", "published_at": "2024-04-01T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-530458b8853a", "title": "Cosmology – Best References for Physics Students", "url": "https://rohankulkarni.me/posts/bibliosphere/grad/cosmology/", "published_at": "2023-12-01T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-5304594a6524", "title": "Ph.D. Physics Applications 101 (Canada and Germany)", "url": "https://rohankulkarni.me/posts/blogs/phd_application_guide/", "published_at": "2023-07-21T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-530459640b9a", "title": "Three Commutator Identities for a Constant Commutator", "url": "https://rohankulkarni.me/posts/notes/commutator-identities/", "published_at": "2023-07-20T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-530459a3c397", "title": "Correlation Function and the Classical Limit", "url": "https://rohankulkarni.me/posts/notes/correlation-function-classical-limit/", "published_at": "2023-07-20T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-53045a222b2b", "title": "The Density Matrix: Six Essential Properties", "url": "https://rohankulkarni.me/posts/notes/density-matrix/", "published_at": "2023-07-20T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-53045aefca3c", "title": "Two-Flavor Neutrino Oscillations", "url": "https://rohankulkarni.me/posts/notes/neutrino-oscillations/", "published_at": "2023-07-20T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-53045bc25046", "title": "Spin-Orbit Interaction as a 2×2 Spinor Operator", "url": "https://rohankulkarni.me/posts/notes/spin-orbit-interaction/", "published_at": "2023-07-20T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-53045c6df13d", "title": "Spin Measurement Probabilities for a General Qubit State", "url": "https://rohankulkarni.me/posts/notes/spin-probabilities/", "published_at": "2023-07-20T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-53045d6b955f", "title": "IPSP Leipzig Part 2- Preparation phase", "url": "https://rohankulkarni.me/posts/blogs/ipsp/ipsp2/", "published_at": "2023-07-18T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-53045e4aa97c", "title": "The Time-Reversal Operator for Spin-1/2 and Why Fermions Need Two Rotations", "url": "https://rohankulkarni.me/posts/notes/time-reversal-spin-half/", "published_at": "2022-11-09T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-53045ec21209", "title": "Angular Momentum Conservation in Particle Decay and Clebsch-Gordan Coefficients", "url": "https://rohankulkarni.me/posts/notes/clebsch-gordan-decay/", "published_at": "2022-10-17T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-53045f6d781d", "title": "Discrete Symmetry Groups: Rotations, Mirrors, and Vanishing Matrix Elements", "url": "https://rohankulkarni.me/posts/notes/discrete-symmetry-groups/", "published_at": "2022-10-17T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-530460456b0e", "title": "WKB Tunneling Through an Arbitrary Barrier", "url": "https://rohankulkarni.me/posts/notes/wkb-tunneling/", "published_at": "2022-10-17T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-53046068cdcf", "title": "Spin Eigenstates in a General Direction", "url": "https://rohankulkarni.me/posts/notes/spin-eigenstates-general/", "published_at": "2022-09-26T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-53046133fb58", "title": "Heidelberg M.Sc. Physics Interview Tips", "url": "https://rohankulkarni.me/posts/blogs/heidelberg_interview/", "published_at": "2022-01-01T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-530461f2f346", "title": "Quantum Field Theory – Best References for Physics Students", "url": "https://rohankulkarni.me/posts/bibliosphere/grad/qft/", "published_at": "2022-01-01T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-53046283b78b", "title": "When 'Hermitian' Isn't Enough: A Case Study of the Momentum Operator", "url": "https://rohankulkarni.me/posts/notes/case-study-momentum/", "published_at": "2021-12-01T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-530463327e4b", "title": "IPSP Leipzig Part 1- Application phase FAQ.", "url": "https://rohankulkarni.me/posts/blogs/ipsp/ipsp1/", "published_at": "2021-08-24T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-530463c2788c", "title": "General Relativity (Heidelberg, SoSe 2021)", "url": "https://rohankulkarni.me/posts/teaching/gr_heidelberg_sose21/", "published_at": "2021-04-16T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-530464b60870", "title": "Electrodynamics – Best References for Physics Students", "url": "https://rohankulkarni.me/posts/bibliosphere/ug/ed/", "published_at": "2021-02-12T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-530465a6d401", "title": "Statistical Mechanics: The Directed Polymer Problem", "url": "https://rohankulkarni.me/posts/notes/directed-polymer/", "published_at": "2020-12-23T00:00:00+00:00" }, { "id": "01a087d7-433d-724f-99c4-5304669365c1", "title": "Theoretical Physics III (Leipzig, WiSe 2019/20)", "url": "https://rohankulkarni.me/posts/teaching/theo_physics_iii_leipzig_ws1920/", "published_at": "2019-10-18T00:00:00+00:00" } ] posts Claim your blog
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rohankulkarni.me

2026

Furry's Theorem, Part 1: Why an Odd Number of Photons Can't Come From Nothingoriginal ↗
25 Jul 2026
Furry's Theorem, Part 2: What It Buys Youoriginal ↗
25 Jul 2026
Self-Energy, 1PI Diagrams, and the Dyson Resummationoriginal ↗
2 May 2026
Why Renormalization Is Needed: The Källén–Lehmann Spectral Representationoriginal ↗
1 May 2026
Starting MSc Physics at Heidelberg — What We Wish We Knew Earlieroriginal ↗
15 Apr 2026
Lie Groups and Lie Algebras, Part IV: The Poincaré Group and the Classification of Particlesoriginal ↗
6 Apr 2026
Lie Groups and Lie Algebras, Part III: Spinors, Fields, and the Representations That Matteroriginal ↗
5 Apr 2026
Lie Groups and Lie Algebras, Part II: The Lorentz Grouporiginal ↗
4 Apr 2026
Lie Groups and Lie Algebras, Part Ioriginal ↗
3 Apr 2026
Faddeev–Popov Quantization (Abelian), Part 2: The Trick, the Propagator, and What Counts as Gauge Fixingoriginal ↗
2 Apr 2026
Faddeev–Popov Quantization (Abelian), Part 1: The Overcounting Problemoriginal ↗
1 Apr 2026

2025

Dark Energy Beyond Scalars, Part IV: Perturbations, Gauge Invariance, and What Propagatesoriginal ↗
23 Dec 2025
Dark Energy Beyond Scalars, Part III: The Cosmological Principle Meets Higher-Rank Fieldsoriginal ↗
21 Dec 2025
Dark Energy Beyond Scalars, Part II: Gauge Symmetry, Mass, and Degrees of Freedomoriginal ↗
20 Dec 2025
Dark Energy Beyond Scalars, Part I: Why p-Forms?original ↗
19 Dec 2025

2024

Cosmology (Heidelberg, WiSe 24/25)original ↗
15 Oct 2024
Bose-Einstein Condensation (1): Can it occur in 1D and 2D?original ↗
24 May 2024
IPSP Leipzig Part 3 - Do's and Don'ts for the courseoriginal ↗
3 May 2024
Classical Mechanics – Best References for Physics Studentsoriginal ↗
7 Apr 2024
Mandelstam Variables in the CM Frameoriginal ↗
3 Apr 2024
Virial Expansion for Hard Spheresoriginal ↗
3 Apr 2024
Advanced Quantum Field Theory (Heidelberg, SoSe 2024)original ↗
1 Apr 2024

2023

Cosmology – Best References for Physics Studentsoriginal ↗
1 Dec 2023
Ph.D. Physics Applications 101 (Canada and Germany)original ↗
21 Jul 2023
Three Commutator Identities for a Constant Commutatororiginal ↗
20 Jul 2023
Correlation Function and the Classical Limitoriginal ↗
20 Jul 2023
The Density Matrix: Six Essential Propertiesoriginal ↗
20 Jul 2023
Two-Flavor Neutrino Oscillationsoriginal ↗
20 Jul 2023
Spin-Orbit Interaction as a 2×2 Spinor Operatororiginal ↗
20 Jul 2023
Spin Measurement Probabilities for a General Qubit Stateoriginal ↗
20 Jul 2023
IPSP Leipzig Part 2- Preparation phaseoriginal ↗
18 Jul 2023

2022

The Time-Reversal Operator for Spin-1/2 and Why Fermions Need Two Rotationsoriginal ↗
9 Nov 2022
Angular Momentum Conservation in Particle Decay and Clebsch-Gordan Coefficientsoriginal ↗
17 Oct 2022
Discrete Symmetry Groups: Rotations, Mirrors, and Vanishing Matrix Elementsoriginal ↗
17 Oct 2022
WKB Tunneling Through an Arbitrary Barrieroriginal ↗
17 Oct 2022
Spin Eigenstates in a General Directionoriginal ↗
26 Sept 2022
Heidelberg M.Sc. Physics Interview Tipsoriginal ↗
1 Jan 2022
Quantum Field Theory – Best References for Physics Studentsoriginal ↗
1 Jan 2022

2021

When 'Hermitian' Isn't Enough: A Case Study of the Momentum Operatororiginal ↗
1 Dec 2021
IPSP Leipzig Part 1- Application phase FAQ.original ↗
24 Aug 2021
General Relativity (Heidelberg, SoSe 2021)original ↗
16 Apr 2021
Electrodynamics – Best References for Physics Studentsoriginal ↗
12 Feb 2021

2020

Statistical Mechanics: The Directed Polymer Problemoriginal ↗
23 Dec 2020

2019

Theoretical Physics III (Leipzig, WiSe 2019/20)original ↗
18 Oct 2019