Ciro Santilli @cirosantilli 37

 Articles (11k) Discussions (26) Comments (64) Follows  Received likes Files

New Updated  Top  Announced  A-Z  Liked  Followed

Strange quark Updated 2025-07-16

 Read the full article

Super Mario Updated 2025-07-16

 Read the full article

Super Nintendo Entertainment System Updated 2025-07-16

 Read the full article

DNS configuration of Ciro Santilli's website Updated 2025-07-16

 View more

AKA how this GitHub page gets served under the domain: cirosantilli.com

Ciro only touches this very rarely, and always forgets and go into great pain whenever a change needs to done, so it is important to document it.

The last change was of 2019-07-07, when Ciro moved from the www subdomain www.cirosantilli.com to the APEX cirosantilli.com. A redirect is setup from the www subdomain to APEX.

GoDaddy DNS entries:

Type    Name    Value                   TTL
A       @       185.199.108.153         1 Hour
A       @       185.199.109.153         1 Hour
A       @       185.199.110.153         1 Hour
A       @       185.199.111.153         1 Hour
CNAME   www     cirosantilli.github.io  1 Hour

Moved cirosantilli.com to Porkbun 2022-02, unfortunatly records were not automatically updated and domain went down for a bit, upadded to new entries for IPv6 as well which are not documented by GitHub:

TYPE 	HOST	ANSWER	TTL	PRIORITY	OPTIONS
A	cirosantilli.com	185.199.108.153	600
A	cirosantilli.com	185.199.109.153	600
A	cirosantilli.com	185.199.110.153	600
A	cirosantilli.com	185.199.111.153	600
AAAA	cirosantilli.com	2606:50c0:8000::153	600
AAAA	cirosantilli.com	2606:50c0:8001::153	600
AAAA	cirosantilli.com	2606:50c0:8002::153	600
AAAA	cirosantilli.com	2606:50c0:8003::153	600
CNAME	www.cirosantilli.com	cirosantilli.github.io	600

where the IPs are obtained from: help.github.com/en/articles/setting-up-an-apex-domain#configuring-a-records-with-your-dns-provider (archive).

Under github.com/cirosantilli/cirosantilli.github.io/settings

Custom domain: cirosantilli.com
Enforce HTTPS: checked

And the CNAME file is tracked in this repository: CNAME.

 Read the full article

Pathological (mathematics) Updated 2025-07-16

 Read the full article

Snowden (film) Updated 2025-07-26

 View more

Video 1.

Aptitude test scene from the Snowden 2016 film

. Source.

Video 2.

FISA Court Order The Guardian discussion scene from the Snowden 2016 film

. Source.

Video 3.

How is this Possible? scene from the Snowden 2016 film

. Source.

Video 4.

Fresh Brains for You scene from the Snowden 2016 film

. Source.

 Read the full article

Thermodynamics Updated 2025-07-16

 Read the full article

Wiki-binge Updated 2025-07-16

 View more

www.urbandictionary.com/define.php?term=wiki-binge

 Read the full article

Docker (software) Updated 2025-07-16

 View more

Docker is good.

As a lightweight virtualization however, it does break more often than full proper virtualization like QEMU after some updates.

The images also appear to randomly update slightly and break things, even though you've specified e.g.:

FROM ubuntu:20.04

Also, we need more Linux distributions buildable from source, especially with Reproducible builds.

 Read the full article

Networking hardware company Updated 2025-07-16

 Read the full article

Nuclear site Updated 2025-07-16

 Read the full article

Physical layer Updated 2025-07-16

 View more

This one is not generally seen by software, which mostly operates starting from OSI layer 2.

 Read the full article

Salted bomb Updated 2025-07-16

 Read the full article

Symmetric matrix Updated 2025-07-16

 View more

A matrix that equals its transpose:

M = M^{T}

(1)

Can represent a symmetric bilinear form as shown at matrix representation of a symmetric bilinear form, or a quadratic form.

 Read the full article

Turbo code Updated 2025-07-16

 View more

TODO how close does it get to Shannon's limit?

 Read the full article

Domain (biology) Updated 2025-07-16

 Read the full article

Nuclear weapons testing Updated 2025-07-16

 Read the full article

Physics YouTube channel Updated 2025-07-16

 Read the full article

Router (computing) Updated 2025-07-16

 Read the full article

Schrödinger equation Updated 2025-07-16

 View more

The partial differential equation of non-relativistic quantum mechanics.

Experiments explained:

via the Schrödinger equation solution for the hydrogen atom it predicts:
- spectral line basic lines, plus Zeeman effect
Schrödinger equation solution for the helium atom: perturbative solutions give good approximations to the energy levels
double-slit experiment: I think we have a closed solution for the max and min probabilities on the measurement wall, and they match experiments

Experiments not explained: those that the Dirac equation explains like:

To get some intuition on the equation on the consequences of the equation, have a look at:

The easiest to understand case of the equation which you must have in mind initially that of the Schrödinger equation for a free one dimensional particle.

Then, with that in mind, the general form of the Schrödinger equation is:

i ℏ \frac{\partial ψ ( x , t )}{\partial t} = \hat{H} [ψ (x, t)]

(1)

Equation 1.

Schrodinger equation

where:

$ℏ$ is the reduced Planck constant
$ψ$ is the wave function
$t$ is the time
$\hat{H}$ is a linear operator called the Hamiltonian. It takes as input a function $ψ$ , and returns another function. This plays a role analogous to the Hamiltonian in classical mechanics: determining it determines what the physical system looks like, and how the system evolves in time, because we can just plug it into the equation and solve it. It basically encodes the total energy and forces of the system.

The

x

argument of

ψ

could be anything, e.g.:

we could have preferred polar coordinates instead of linear ones if the potential were symmetric around a point
we could have more than one particle, e.g. solutions of the Schrodinger equation for two electrons, which would have e.g. $x_{1}$ and $x_{2}$ for different particles. No matter how many particles there are, we have just a single $ψ$ , we just add more arguments to it.
we could have even more generalized coordinates. This is much in the spirit of Hamiltonian mechanics or generalized coordinates

Note however that there is always a single magical

t

time variable. This is needed in particular because there is a time partial derivative in the equation, so there must be a corresponding time variable in the function. This makes the equation explicitly non-relativistic.

The general Schrödinger equation can be broken up into a trivial time-dependent and a time-independent Schrödinger equation by separation of variables. So in practice, all we need to solve is the slightly simpler time-independent Schrödinger equation, and the full equation comes out as a result.

Existence and uniqueness: mathoverflow.net/questions/212913/existence-and-uniqueness-for-two-dimensional-time-dependent-schr%C3%B6dinger-equation

 Read the full article

 Unlisted articles are being shown, click here to show only listed articles.