Quantum field theory lecture by Tobias Osborne (2017) Lecture 2 Updated 2025-07-14 +Created 1970-01-01
- the advantage of using Lagrangian mechanics instead of directly trying to work out the equations of motion is that it is easier to guess the Lagrangian correctly, while still imposing some fundamental constraints
- youtu.be/bTcFOE5vpOA?list=PLDfPUNusx1EpRs-wku83aqYSKfR5fFmfS&t=3375
- Lagrangian mechanics is better for path integral formulation. But the mathematics of that is fuzzy, so not going in that path.
- Hamiltonian mechanics is better for non-path integral formulation
- youtu.be/bTcFOE5vpOA?list=PLDfPUNusx1EpRs-wku83aqYSKfR5fFmfS&t=3449 Hamiltonian formalism requires finding conjugate pairs, and doing a
Not everything is perfect.
One big problem of many big open source projects is that they are contributed to by separate selfish organizations, that have private information. Then what happens is that:
- people implement the same thing twice, or one change makes the other completely unmergeable
- you get bugs but can't share your closed source test cases, and then you can't automate tests for them, or clearly demonstrate the problem
- other contributors don't see your full semi secret important motivation, and may either nitpick too much or take too long to review your stuff
Another common difficulty is that open source maintainers may simply not care enough about their own project (maybe they did in the past but lost interest) to review external patches by people they don't know.
Therefore, if you ever submit patches and they get ignore, don't be too sad. It just comes down to a question of maintenance cost, and means that you will waste some extra time on the next rebase. You just have to decide your goals and be cold about it:
- are you doing the right thing and going for a specific goal backward design? Then just fork, run as fast as possible towards a minimum viable product, and if you start to feel that rebase is costing you a lot, or feel you could get some open source fame for cheap, open reviews and see what upstream says. If they ignore you, politely tell yourself in your mind silently "fuck them", and carry on with the MVP
- otherwise, e.g. you just want to randomly help out, you have to ask them before doing anything big "how can I be of help". If I propose a patch for this issue, do you promise to review it?
Writing documentation in an open source project in which you don't have immediate push rights is another major pain due to code reviews. Code code reviews tend to be much less subjective, because if you do something wrong, stuff crashes, runs slower, or you need more lines of code to reach the same goal. There are tradeoffs, but in a limited number. Documentation code reviews on the other hand, are an open invitation to infinite bike-shedding, since you can't "run" documentation through a standardized brain model. Much better is for one good documenter person to just make one cohesive Stack Overflow post, and ping others with more knowledge to review details or add any missing pieces :-)
- HyperCard: we are kind of a "multiuser" version of HyperCard, trying to tie up cards made by different users. It is worth noting that HyperCard was one of the inspirations for WikiWikiWeb, which then inspired Wikipedia
- Semantic Web
- NLab
- physicstravelguide.com/ Nice manifesto: physicstravelguide.com/about by Jakob Schwichtenberg.
- OpenStax
- www.ft.com/content/5515ec3e-0040-4d90-85a9-df19d6e3ebd2 (archive) Twilio’s Jeff Lawson: an evangelist for software developersYou can never be first. But you can have the correct business model. That company's website must have gone into IP Purgatory, and could never be released as an open source website.As a student at the University of Michigan, he started a company that made lecture notes available free online, drawing a large audience of Midwestern college students and, soon enough, advertisers. At the height of the dotcom bubble, he dropped out of college, raised $10m from the venture firm Venrock and moved the company to Silicon Valley.His start-up drew interest from an acquirer that was planning to go public early in 2000. They closed the acquisition but missed their IPO window as the market plunged, and by August the company had filed for bankruptcy. Stock that Lawson and investors in his start-up received from the sale became worthless.He might actually be interested in donating to OurBigBook.com if it move forward now that he's a billionaire.
- Knol: basically the exact same thing by Google but 14 years earlier and declared a failure. Quite ominous:
- leanpub: similar goals, markdown-based, but the usual "you own your book copyright and you are trying to sell your book" approach
- nature Scitable
OK, just going random now:
Composed mostly of the Virgo cluster and the Local group.
Refrigerator - How Does It Work? by Curiosity Show
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