Merkle tree Updated 2025-07-16
Paul Allen Updated 2025-07-16
PCI Updated 2025-07-16
Personal computer Updated 2025-07-16
Personalized learning Updated 2025-07-16
Inferior compared to self-directed learning, but better than the traditional "everyone gets the same" approach.
Phase shift gate Updated 2025-07-16
Phi Updated 2025-07-16
C3 Updated 2025-07-16
Year 4 Updated 2025-07-16
Sylvain Poirier Updated 2025-07-16
Ciro Santilli feels a bit like this guy:
- he's also an idealist, even more than Ciro. So cute. Notably, he he also dumps his brain online into pages that no-one will ever read
- he also thinks that the 2010's education system is bullshit, e.g. settheory.net/learnphysics
- trust-forum.net/ some kind of change the world website. But:is a sin to Ciro. Planning a change the world thing behind closed doors? Really? Decentralized, meh.
- antispirituality.net/ his atheism website
singlesunion.org/ so cute, he's looking for true love!!! This is something Ciro often thinks about: why it is so difficult to find love without looking people in the eye. The same applies to jobs to some extent. He has an Incel wiki page: incels.wiki/w/Sylvain_Poirier :-)
Physics journal Updated 2025-07-16
The strongest are:
- early 20th century: Annalen der Physik: God OG physics journal of the early 20th century, before the Nazis fucked German science back to the Middle Ages
- 20s/30s: Nature started picking up strong
- 40s/50s: American journals started to come in strong after all the genius Jews escaped from Germany, notably Physical Review Letters
Sylvester's law of inertia Updated 2025-07-16
The main interest of this theorem is in classifying the indefinite orthogonal groups, which in turn is fundamental because the Lorentz group is an indefinite orthogonal groups, see: all indefinite orthogonal groups of matrices of equal metric signature are isomorphic.
It also tells us that a change of basis does not the alter the metric signature of a bilinear form, see matrix congruence can be seen as the change of basis of a bilinear form.
The theorem states that the number of 0, 1 and -1 in the metric signature is the same for two symmetric matrices that are congruent matrices.
For example, consider:
The eigenvalues of are and , and the associated eigenvectors are:symPy code:and from the eigendecomposition of a real symmetric matrix we know that:
A = Matrix([[2, sqrt(2)], [sqrt(2), 3]])
A.eigenvects()
Now, instead of , we could use , where is an arbitrary diagonal matrix of type:With this, would reach a new matrix :Therefore, with this congruence, we are able to multiply the eigenvalues of by any positive number and . Since we are multiplying by two arbitrary positive numbers, we cannot change the signs of the original eigenvalues, and so the metric signature is maintained, but respecting that any value can be reached.
Note that the matrix congruence relation looks a bit like the eigendecomposition of a matrix:but note that does not have to contain eigenvalues, unlike the eigendecomposition of a matrix. This is because here is not fixed to having eigenvectors in its columns.
But because the matrix is symmetric however, we could always choose to actually diagonalize as mentioned at eigendecomposition of a real symmetric matrix. Therefore, the metric signature can be seen directly from eigenvalues.
What this does represent, is a general change of basis that maintains the matrix a symmetric matrix.
Symbolic artificial intelligence Updated 2025-07-16
Synthetic data Updated 2025-07-16
Obsidian (software) Updated 2025-07-16
Good:
- WYSIWYG
- Extended-Markdown-based
- help.obsidian.md/Getting+started/Sync+your+notes+across+devices they do have a device sync mechanism
- it watches the filesystem and if you change anything it gets automatically updated on UI
- help.obsidian.md/links#Link+to+a+block+in+a+note you can set (forcibly scoped) IDs to blocks. But it's not exposed on WYSIWYG?
Bad:
- forced ID scoping on the tree as usual
- no browser-only editor, it's just a local app apparently:
- obsidian.md/publish they have a publish function, but you can't see the generated websites with JavaScript turned off. And they charge you 8 dollars / month for that shit. Lol.
- block elements like images and tables cannot have captions?
- they kind of have synonyms: help.obsidian.md/aliases but does it work on source code?
Synthetic geometry of the real projective plane Updated 2025-07-16
It good to think about how Euclid's postulates look like in the real projective plane:
- Since there is one point of infinity for each direction, there is one such point for every direction the two parallel lines might be at. The parallel postulate does not hold, and is replaced with a simpler more elegant version: every two lines meet at exactly one point.One thing to note however is that ther real projective plane does not have angles defined on it by definition. Those can be defined, forming elliptic geometry through the projective model of elliptic geometry, but we can interpret the "parallel lines" as "two lines that meet at a point at infinity"
- points in the real projective plane are lines in
- lines in the real projective plane are planes in .For every two projective points there is a single projective line that passes through them.Note however that not all lines in the real plane correspond to a projective line: only lines tangent to a circle at zero do.
Unlike the real projective line which is homotopic to the circle, the real projective plane is not homotopic to the sphere.
The topological difference bewteen the sphere and the real projective space is that for the sphere all those points in the x-y circle are identified to a single point.
One more generalized argument of this is the classification of closed surfaces, in which the real projective plane is a sphere with a hole cut and one Möbius strip glued in.
Tank Man Updated 2025-07-16
Telecommunication Updated 2025-07-16
A very cool thing about telecommunication is, besides how incredibly fast it advanced (in this sense it is no cooler than integrated circuit development), how much physics and information theory is involved in it. Applications of telecommunication implementation spill over to other fields, e.g. some proposed quantum computing approaches are remarkably related to telecommunication technology, e.g. microwaves and silicon photonics.
This understanding made Ciro Santilli wish he had opted for telecommunication engineering when he was back in school in Brazil. For some incomprehensible reason, telecommunications was the least competitive specialization in the electric engineering department at the time, behind even power electronics. This goes to show both how completely unrelated to reality university is, and how completely outdated Brazil is/was. Sad stuff.
Telegram (software) Updated 2025-07-16
Not end-to-end encrypted by default, WTF... you have to create "secret chats" for that:
You can't sync secret chats across devices, Signal handles that perfectly by sending E2EE messages across devices:This is a deal breaker because Ciro needs to type with his keyboard.
Desktop does not have secret chats: www.reddit.com/r/Telegram/comments/9beku1/telegram_desktop_secret_chat/ This is likey because it does not store chats locally, it just loads from server every time as of 2019: www.reddit.com/r/Telegram/comments/baqs63/where_are_chats_stored_on_telegram_desktop/ just like the web version. So it cannot have a private key.
Allows you to register a public username and not have to share phone number with contacts: telegram.org/blog/usernames-and-secret-chats-v2.
Self deleting messages added to secret chats in Q1 2021: telegram.org/blog/autodelete-inv2
Can delete messages from the device of the person you sent it to, no matter how old.
Telephone-based system Updated 2025-07-16
This section is about telecommunication systems that are based on top of telephone lines.
Telephone lines were ubiquitous from early on, and many technologies used them to send data, including much after regular phone calls became obsolete with VoIP.
These market forces tended to eventually crush non-telephone-based systems such as telex. Maybe in that case it was just that the name sounded like a thing of the 50's. But still. Dead.
Long Distance by AT&T (1941)
Source. youtu.be/aRvFA1uqzVQ?t=219 is perhaps the best moment, which attempts to correlate the exploration of the United States with the founding of the U.S. states. Unlisted articles are being shown, click here to show only listed articles.