This actually happens in spring. But because they are so euphemistic winter had to be removed from the calendar, it gets shifted a left.
Probable observation of the Josephson superconducting tunneling effect by 
Ciro Santilli 37 Updated 2025-07-16
Ciro Santilli 37 Updated 2025-07-16Paper by Philip W. Anderson and John M. Rowell that first (?) experimentally observed the Josephson effect.
Paywalled by the American Physical Society as of 2023 at: journals.aps.org/prl/abstract/10.1103/PhysRevLett.10.230
They used tin-oxide-lead tunnel at 1.5 K. TODO oxide of what? Why two different metals? They say that both films are 200 nm thick, so maybe it is:
-----+------+------+-----
... Sn | SnO2 | PbO2 | Pb ...
-----+------+------------
100nm 100nmA reconstruction of their circuit in Ciro's ASCII art circuit diagram notation TODO:
DC---R_10---X---GThere are not details of the physical construction of course. Reproducibility lol.
Principles of the Optical Maser by Bell Labs
. Source. Date: 1963.The most classic thing he did perhaps was creating the LeNet neural network and using it on the MNIST dataset to recognize hand-written digits circ 1998.
Not only did this open the way for X-ray crystallography, it more fundamentally clarified the nature of X-rays as being electromagnetic radiation, and helped further establish the atomic theory.
This paper appears to calculate the Schrödinger equation solution for the hydrogen atom.
TODO is this the original paper on the Schrödinger equation?
Published on Annalen der Physik in 1926.
Open access in German at: onlinelibrary.wiley.com/doi/10.1002/andp.19263840404 which gives volume 384, Issue 4, Pages 361-376. Kudos to Wiley for that. E.g. Nature did not have similar policies as of 2023.
This paper may have fallen into the public domain in the US in 2022! On the Internet Archive we can see scans of the journal that contains it at: ia903403.us.archive.org/29/items/sim_annalen-der-physik_1926_79_contents/sim_annalen-der-physik_1926_79_contents.pdf. Ciro Santilli extracted just the paper to: commons.wikimedia.org/w/index.php?title=File%3AQuantisierung_als_Eigenwertproblem.pdf. It is not as well processed as the Wiley one, but it is of 100% guaranteed clean public domain provenance! TODO: hmmm, it may be public domain in the USA but not Germany, where 70 years after author deaths rules, and Schrodinger died in 1961, so it may be up to 2031 in that country... messy stuff. There's also the question of wether copyright is was tranferred to AdP at publication or not.
Per-table dumps created with mysqldump and listed at: dumps.wikimedia.org/. Most notably, for the English Wikipedia: dumps.wikimedia.org/enwiki/latest/
A few of the files are not actual tables but derived data, notably dumps.wikimedia.org/enwiki/latest/enwiki-latest-all-titles-in-ns0.gz from Download titles of all Wikipedia articles
The tables are "documented" under: www.mediawiki.org/wiki/Manual:Database_layout, e.g. the central "page" table: www.mediawiki.org/wiki/Manual:Page_table. But in many cases it is impossible to deduce what fields are from those docs.
The generic tool recommendation question: unix.stackexchange.com/questions/7425/is-there-a-robust-command-line-tool-for-processing-csv-files
dumps.wikimedia.org/enwiki/latest/enwiki-latest-category.sql.gz contains a list of categories. It only contains the categories and some counts, but it doesn't contain the subcategories and pages under each category, so it is a bit pointless.
The schema is listed at: www.mediawiki.org/wiki/Manual:Category_table
The SQL first defines the table:followed by a few humongous inserts:which we can see at: en.wikipedia.org/wiki/Category:Computer_storage_devices
CREATE TABLE `category` (
`cat_id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`cat_title` varbinary(255) NOT NULL DEFAULT '',
`cat_pages` int(11) NOT NULL DEFAULT 0,
`cat_subcats` int(11) NOT NULL DEFAULT 0,
`cat_files` int(11) NOT NULL DEFAULT 0,
PRIMARY KEY (`cat_id`),
UNIQUE KEY `cat_title` (`cat_title`),
KEY `cat_pages` (`cat_pages`)
) ENGINE=InnoDB AUTO_INCREMENT=249228235 DEFAULT CHARSET=binary ROW_FORMAT=COMPRESSED;INSERT INTO `category` VALUES (2,'Unprintworthy_redirects',1597224,20,0),(3,'Computer_storage_devices',88,11,0)Se see that en.wikipedia.org/wiki/Category:Computer_storage_devices_by_companyso it contains only categories.
- en.wikipedia.org/wiki/Category:Computer_storage_devices is a subcategory of that category and it appears in that file.
- en.wikipedia.org/wiki/Acronis_Secure_Zone is a page of the category, and it does not appear
We can check this with:and it shows:There doesn't seem to be any interlink between the categories, only page and subcategory counts therefore.
sed -s 's/),/\n/g' enwiki-latest-category.sql | grep Computer_storage_devices(3,'Computer_storage_devices',88,11,0
(521773,'Computer_storage_devices_by_company',6,6,0The schema is listed at: www.mediawiki.org/wiki/Manual:Categorylinks_table
On the SQL:
CREATE TABLE `categorylinks` (
`cl_from` int(8) unsigned NOT NULL DEFAULT 0,
`cl_to` varbinary(255) NOT NULL DEFAULT '',
`cl_sortkey` varbinary(230) NOT NULL DEFAULT '',
`cl_timestamp` timestamp NOT NULL DEFAULT current_timestamp() ON UPDATE current_timestamp(),
`cl_sortkey_prefix` varbinary(255) NOT NULL DEFAULT '',
`cl_collation` varbinary(32) NOT NULL DEFAULT '',
`cl_type` enum('page','subcat','file') NOT NULL DEFAULT 'page',
PRIMARY KEY (`cl_from`,`cl_to`),
KEY `cl_timestamp` (`cl_to`,`cl_timestamp`),
KEY `cl_sortkey` (`cl_to`,`cl_type`,`cl_sortkey`,`cl_from`),
KEY `cl_collation_ext` (`cl_collation`,`cl_to`,`cl_type`,`cl_from`)
) ENGINE=InnoDB DEFAULT CHARSET=binary ROW_FORMAT=COMPRESSED;The format appears to be described at: www.mediawiki.org/wiki/Manual:Categorylinks_table
A sample INSERT entry is:
(3,'Computer_storage_devices',88,11,0)dumps.wikimedia.org/enwiki/latest/enwiki-latest-all-titles-in-ns0.gz Characterization:
- contains redirects, e.g. en.wikipedia.org/wiki/"Ampere_North" redirects to en.wikipedia.org/wiki/Ampere_North,_New_Jersey and both are present. Noted in this comment: stackoverflow.com/questions/24474288/how-to-obtain-a-list-of-titles-of-all-wikipedia-articles#comment136016773_24474476
Our WIP script: wikipedia/import-categories.sh.
Related:
- opendata.stackexchange.com/questions/1533/download-wikipedia-articles-from-a-specific-category
- webapps.stackexchange.com/questions/16359/is-there-a-way-to-download-a-list-of-all-wikipedia-categories/172480#172480
- stackoverflow.com/questions/40119322/how-to-download-all-pages-inside-a-category-in-wikipedia
- category tree on Stack Overflow
- stackoverflow.com/questions/17432254/wikipedia-category-hierarchy-from-dumps/77313490#77313490 Canon but no good answers.
- stackoverflow.com/questions/12227134/how-to-fetch-category-tree-of-wiki
- stackoverflow.com/questions/21782410/finding-subcategories-of-a-wikipedia-category-using-category-and-categorylinks-t. Actually explains it: stackoverflow.com/questions/21782410/finding-subcategories-of-a-wikipedia-category-using-category-and-categorylinks-t/21798259#21798259
- stackoverflow.com/questions/27279649/how-to-build-wikipedia-category-hierarchy
- mdkzaman.com/knowledge-graph-from-wikipedia-category-hierarchy/
Consider:
Let's observe them in MySQL:outputs:
mysql enwiki -e "select page_id, page_namespace, page_title, page_is_redirect from page where page_namespace in (0, 14) and page_title in ('Computer_storage_devices', 'Computer_data_storage')"+----------+----------------+--------------------------+------------------+
| page_id | page_namespace | page_title | page_is_redirect |
+----------+----------------+--------------------------+------------------+
| 5300 | 0 | Computer_data_storage | 0 |
| 42371130 | 0 | Computer_storage_devices | 1 |
| 711721 | 14 | Computer_data_storage | 0 |
| 895945 | 14 | Computer_storage_devices | 0 |
+----------+----------------+--------------------------+------------------+mysql enwiki -e "select cl_from, cl_to from categorylinks where cl_from in (5300, 711721, 895945, 42371130)"+----------+-----------------------------------------------------------------------+
| cl_from | cl_to |
+----------+-----------------------------------------------------------------------+
| 5300 | All_articles_containing_potentially_dated_statements |
| 5300 | Articles_containing_potentially_dated_statements_from_2009 |
| 5300 | Articles_containing_potentially_dated_statements_from_2011 |
| 5300 | Articles_with_GND_identifiers |
| 5300 | Articles_with_NKC_identifiers |
| 5300 | Articles_with_short_description |
| 5300 | Computer_architecture |
| 5300 | Computer_data_storage |
| 5300 | Short_description_matches_Wikidata |
| 5300 | Use_dmy_dates_from_June_2020 |
| 5300 | Wikipedia_articles_incorporating_text_from_the_Federal_Standard_1037C |
| 711721 | Computer_architecture |
| 711721 | Computer_data |
| 711721 | Computer_hardware_by_type |
| 711721 | Data_storage |
| 895945 | Computer_data_storage |
| 895945 | Computer_peripherals |
| 895945 | Recording_devices |
| 42371130 | Redirects_from_alternative_names |
+----------+-----------------------------------------------------------------------+So we see that
cl_from encodes the parent categories:- parent categories of categories:
- en.wikipedia.org/wiki/Category:Computer_data_storage, which has ID
711721, has parent categories: "Computer hardware by type", "Computer data", "Data storage", "Computer architecture". This matches exactly on the database. These are all encoded on the source code of the page:{{DEFAULTSORT:Storage}} [[Category:Computer hardware by type]] [[Category:Computer data|Storage]] [[Category:Data storage|Computer]] [[Category:Computer architecture]] - en.wikipedia.org/wiki/Category:Computer_storage_devices has parent categories: "Computer data storage", "Recording devices", "Computer peripherals". This matches exactly on the database.
- en.wikipedia.org/wiki/Category:Computer_data_storage, which has ID
- parent categories of pages:
- en.wikipedia.org/wiki/Computer_storage_devices whish is a redirect gets the magic category "Redirects_from_alternative_names", a humongous placeholder with many thousands of pages: en.wikipedia.org/wiki/Category:Redirects_from_alternative_names
- en.wikipedia.org/wiki/Computer_data_storage shows only two categories onthe web UI: "Computer data storage" and "Computer architecture". Both of these are present on the database and at the end of the source code:The others appear to be more magic. Two of them we can guess from the templates:
{{DEFAULTSORT:Computer Data Storage}} [[Category:Computer data storage| ]] [[Category:Computer architecture]]are likely{{short description|Storage of digital data readable by computers}} {{Use dmy dates|date=June 2020}}Use_dmy_dates_from_June_2020andArticles_with_short_descriptionbut the rest is more magic and not necessarily present in-source.
So to find all articls and categories under a given category title, say en.wikipedia.org/wiki/Category:Mathematics we can run:
mariadb enwiki -e "select cl_from, cl_to, page_namespace, page_title from categorylinks inner join page on page_namespace in (0, 14) and cl_from = page_id and cl_to = 'Mathematics'" There are unlisted articles, also show them or only show them.