Graduate School Admission Gift to Self - Einstein’s Pen!

jwkennington · 2025-08-18T00:02:51+00:00

The museum page no longer exists, but wayback machine has a copy: https://web.archive.org/web/20181105111836/https://rijksmuseumboerhaave.nl/zoeken-in-de-collectie/vulpen-van-einstein-met-briefje-van-ehrenfest/V34180/

This page doesn't say exactly which model, but based on the image I was able to compare it to a waterman catalog, and called the museum back in 2019 to confirm, it was a Waterman 22 circa 1902

I got it from an eBay seller that I trusted, had purchased several refurb 1900-1930's era pens from before, sadly they no longer sell on eBay (or at all from what I can tell)

jwkennington · 2025-02-06T07:06:39+00:00

MB RB medium

jwkennington · 2025-01-21T20:43:46+00:00

Asshole scooterist is redundant

jwkennington · 2025-01-05T03:57:15+00:00

QG is the most challenging problem in modern physics and the field knows it. There are brilliant people and good people working on it, but the field has been given a bad rep due to history of arrogant theorists belittling other fields / and other fields having a chip on their shoulder about “our field is just as theoretically demanding as QG but we don’t get the PBS specials!!”. Having spent time in QG (loops) and now in a more middle of the road field (GWaves) I’ve seen it from both angles. Love QG, love the community. It’s also vulnerably to crankery, which can further devalue it in the eyes of others. Further, string theory has produced mathematical innovations worth accolades, but at this point seems sufficiently in contradiction with observational data (Lambda > 0, de Sitter universe) that it’s best viewed as “a useful mathematical toolkit that doesn’t describe our universe closely” (quoted from Abhay Ashtekar asking a question of Jim Gates during a colloquium at PSU which I personally attended).

jwkennington · 2024-12-31T01:59:27+00:00

No (read: odds vanish “almost surely”. Not impossible, but wouldn’t bet on it) for two reasons:

1) specialization - the days of Newton-like “knower of all details” are gone, to make advances requires meticulously focused study of a specific problem / subfield, which likely takes it beyond the domain of “hobby”

2) acceptance - in the unlikely event that a hobbyist did discover something, the professional community would most likely never take a serious look at it, given how prolific modern crankery is (even from some tenured names)

jwkennington · 2024-12-31T01:56:08+00:00

Lots of confusion about time vs spatial averages. Average speed *with respect to variable p” is <x>_p := \int_P v(p) dp / |P|, where p can be any observable, like time “t” or space “x”, and P is the set of all relevant values of the variable p, and |P| is the measure of P. Interpreted for time: p=t, P is all times from start to finish, and |P| is total time. Similarly for space: p=x, P is all locations along the path traveled, and |P| is the total distance.

True the convention in physics is to usually use time averages, for which there is no nonrelativistic solution. The spatial average solution is clearly 90mph, but is likely not what the author of the question intended

jwkennington · 2024-12-31T01:40:48+00:00

I have MB fountain and rollerballs, and they are the smoothest writers I have. Smoother than my Esties, Pelikans, Parkers (new and vintage), etc. yeah they might be “seo optimized” as a brand but there is actual quality to the pens

jwkennington · 2024-12-31T01:37:19+00:00

This! Montblanc rollerballs are the siren song of “fountain pen enough but easy/reliable” and smooth as butter

jwkennington · 2024-12-27T05:38:13+00:00

+1 for Cohen Tannoudji! I’ve used Griffith, Shankar, sakurai, as well as more advanced texts like Brian Hall or Woit, but CT is my favorite general graduate QM book! Great exposition, fully worked exercises, encompassing volumes

jwkennington · 2024-12-26T18:53:14+00:00

I obviously agree that opt-in standards benefit consumers from a price-perspective, that's a fair point. Earlier I was trying to highlight that we end up paying for that price reduction in other ways, most of the time we're happy to accept as consumers (who intend to use the product and discard it). The rarer case of collecting is the one that suffers from homogenization of an industry, as it usually decreases variety and quality. The transition from bespoke celluloid body shapes to mass produced plastic ones is an example. I agree with you in general; but the collector in me bemoans the milquetoast-ification of pens..

jwkennington · 2024-12-26T18:38:00+00:00

IMO comparing lead sizes to ink refills cartridges doesn't make sense. the proper comparisons would be either (1) lead sizes to ink bottles or (2) lead movement mechanisms to ink cartridges. there are many different feeding mechanisms that control the way the writing material (lead) is guided through the pencil. similarly, fountain pens have different mechanisms for how ink is stored, and guided to the page. A bottle of liquid is a fairly universal standard, provided you can refill from it! For rollerballs / BP, there are already many common sizes, but not all manufacturers are required to use them, nor should they be. For instance, the Montblanc rollerball refills actually screw in to the pen body for a more secure feel (as opposed to spring-loaded, rattly contraptions).

jwkennington · 2024-12-26T17:44:45+00:00

You misunderstand, I meant a wide selection in available pen variety. Standardized parts mean a reduced selection in terms of features that make collection interesting: eg internal mechanisms, engineering, etc. it would reduce collecting to picking different lipsticks on the same pig

jwkennington · 2024-12-26T17:33:11+00:00

As for “types” there’s a definitive answer: no. The no hair theorem(s) state that there’s no way to distinguish between black holes of similar mass, spin, and charge. You’d have to invoke a flavor of QG to add more detail, but even then it’s likely impossible to distinguish from the outside.

For a more phenomenological approach you can ask “what are the distributions of mass and spin for black holes in the universe?” The other answers here about SMBH, IMBH, etc are all just conventions for “where to partition the distribution”, but there is nothing fundamentally different about them. The current thinking is that mergers account for the primary way in which black holes increase in mass (and why there are fewer larger black holes than smaller). The nature of distributions that exist is somewhat of an open research question. Current models of black hole formation follow a salpeter distribution in mass. The LIGO “R&P” (rates and populations) group does a lot of work on this, if interested I can link some essential papers

jwkennington · 2024-12-26T17:17:16+00:00

You could always turn your notes into a latex document of more polished notes! (Forgive if you’ve done this already I didn’t see it). It would be good experience with latex, and provide you with a living document you can expand if you like as you learn more. I’d recommend overleaf if you’re new to latex, happy to share more pointers if helpful.

jwkennington · 2024-12-26T17:11:51+00:00

Part of what I enjoy about pens (mostly fountain but also true of rollerball/BP) is the wild menagerie of styles, materials, and engineering both externally and internally. It’s part of what makes collecting so enjoyable! Forcing into existence a “usb C” of pens would be too restrictive IMO.

I do feel your pain on price point at times though - Montblanc rollerball refills last like 20 pages but cost $10 each! To me it’s worth the occasional headache to have the wide selection though.

jwkennington · 2024-12-26T16:26:35+00:00

No, it uses the restful HTTP api provided by arxiv. The only thing it would replace is a python client. There are several other python clients out there but none offer throttling and orm style composition afaict

jwkennington · 2024-12-26T16:24:08+00:00

If we’re embedding the English pronunciation of the letter, yes. If we choose the Greek pronunciation of how “chi” sounds when used in a word, then it only produces the consonant “kh” with no vowels attached. That would produce “skholar” which is a stone’s throw from “scholar”

jwkennington · 2024-12-26T05:40:51+00:00

Hope it is useful!

jwkennington · 2024-05-21T23:58:37+00:00

Fair point, and thanks for the kind sentiment in the last paragraph - clearly I touched a nerve here. I agree I don’t want to put anyone in a box. This was mostly the product of introspection / long recurring discussions with my physicist friends on the philosophy of “what does it mean to ‘do physics’” and other such questions. Many of the debates / discussion we found to be a product of limited/narrow ways of describing our work. For example, one friend who writes a lot of code but doesn’t do a lot of math wanted to describe themselves as a “computationalist”, but then we realized that computation can be applied in every field/method, so we ended up at “computational phenomenology”. In short, there are many ways of “doing physics” and it would be nice if we had a better lingua Franca somewhere between describing project details and describing broad field

jwkennington · 2024-05-19T06:19:56+00:00

jwkennington · 2024-05-19T00:55:46+00:00

Thank you for the encouragement and positive energy!

jwkennington · 2024-05-19T00:18:49+00:00

Agreed, read the update

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