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Pipa player by

Ciro Santilli 37 Updated 2025-07-16

Atomic Data and Nuclear Data Tables by

Gamma counter by

Schrödinger picture example: quantum harmonic oscillator by

Ciro Santilli 37 Updated 2025-07-16

TODO: use the results from the quantum harmonic oscillator solution to precisely illustrate the discussion at Schrödinger picture with a concrete example.

Open access at the University of Oxford by

Ciro Santilli 37 Updated 2025-07-16

Things actually have gotten more and more closed, e.g. of stuff getting paywalled with time:

It appears that things got really bad starting in 2017, possibly when WebLearn was introduced. When things migrated to Canvas, they were closed by default, apparently with any mechanism to publish publicly.

Therefore, they managed to make things more closed than when teachers would just upload to good old ox.ac.uk/~name static websites!!

Ciro Santilli has also heard that some people in the Mathematical Institute of the University of Oxford opposed to moving away from their Moodle instance precisely because the new options did not support open publishing, so kudos to those people. But most teachers likely don't care and just do whatever is the best internally supported default.

Their "open" video material: podcasts.ox.ac.uk/ A somewhat small part is Creative Commons, but most proprietary. Despite the name "podcasts", they do contain video, it is just a relic.

podcasts.ox.ac.uk/open contains actual Creative Commons only it seems.

It does however appear that professors own their lecture notes, so there some hope maybe: governance.admin.ox.ac.uk/legislation/statute-xvi-property-contracts-and-trusts#collapse1383636

Talks: talks.ox.ac.uk/. Mathematical, Physical and Life Sciences (MPLS) subset: talks.ox.ac.uk/talks/department/id/oxpoints:23232639

Video 1.

University of Oxford documentary by the British Council (1941)

Source.

Natural (music) by

1987 Nobel Prize in Physics by

Ciro Santilli 37 Updated 2025-07-16

This was so hot (no pun intended) and reproducible that the prize was awarded one year after discovery. Quite rare in those days already.

x86 Paging Tutorial / K-ary trees to the rescue by

Ciro Santilli 37 Updated 2025-07-16

The algorithmically minded will have noticed that paging requires associative array (like Java Map of Python dict()) abstract data structure where:

the keys are linear pages addresses, thus of integer type
the values are physical page addresses, also of integer type

The single level paging scheme uses a simple array implementation of the associative array:

the keys are the array index
this implementation is very fast in time
but it is too inefficient in memory

and in C pseudo-code it looks like this:

linear_address[0]      = physical_address_0
linear_address[1]      = physical_address_1
linear_address[2]      = physical_address_2
...
linear_address[2^20-1] = physical_address_N

But there another simple associative array implementation that overcomes the memory problem: an (unbalanced) k-ary tree.

A K-ary tree, is just like a binary tree, but with K children instead of 2.

Using a K-ary tree instead of an array implementation has the following trade-offs:

it uses way less memory
it is slower since we have to de-reference extra pointers

In C-pseudo code, a 2-level K-ary tree with K = 2^10 looks like this:

level0[0] = &level1_0[0]
    level1_0[0]      = physical_address_0_0
    level1_0[1]      = physical_address_0_1
    ...
    level1_0[2^10-1] = physical_address_0_N
level0[1] = &level1_1[0]
    level1_1[0]      = physical_address_1_0
    level1_1[1]      = physical_address_1_1
    ...
    level1_1[2^10-1] = physical_address_1_N
...
level0[N] = &level1_N[0]
    level1_N[0]      = physical_address_N_0
    level1_N[1]      = physical_address_N_1
    ...
    level1_N[2^10-1] = physical_address_N_N

and we have the following arrays:

one directory, which has 2^10 elements. Each element contains a pointer to a page table array.
up to 2^10 pagetable arrays. Each one has 2^10 4 byte page entries.

and it still contains 2^10 * 2^10 = 2^20 possible keys.

K-ary trees can save up a lot of space, because if we only have one key, then we only need the following arrays:

one directory with 2^10 entries
one pagetable at directory[0] with 2^10 entries
all other directory[i] are marked as invalid, don't point to anything, and we don't allocate pagetable for them at all

1955 Nobel Prize in Physics by

Ciro Santilli 37 Updated 2025-07-16

The key initial quantum electrodynamics experiments:

Willis Lamb for the Lamb-Retherford experiment
Polykarp Kusch for the anomalous magnetic dipole moment of the electron, key publication: The Magnetic Moment of the Electron by Kusch and Foley (1948)

Notations by

1932 Nobel Prize in Physics by

Ciro Santilli 37 Updated 2025-07-16

To Ernest Lawrence for the cyclotron.

Polytope by

Ciro Santilli 37 Updated 2025-07-16

A polygon is a 2-dimensional polytope, polyhedra is a 3-dimensional polytope.

Solutions for the Schrodinger equation with multiple particles by

Ciro Santilli 37 Updated 2025-07-16

Bibliography:

Quantum Mechanics for Engineers by Leon van Dommelen (2011) "5. Multiple-Particle Systems"

Notehead by

Hund's second rule by

Ciro Santilli 37 Updated 2025-07-16

Weekend by

Ciro Santilli 37 Updated 2025-07-16

Days of the week where you don't do what you set out to do. And yet, it is in those days that you save your sanity, and possibly the world. Wait, this sounds exactly like a week day?

Figure 1.
Calvin and Hobbes "Oh No! I overslept! I gotta get up!" cartoon
. Source.

Robot form factor by

Ciro Santilli 37 Updated 2025-07-16

Arm on tracks by

Ciro Santilli 37 Updated 2025-07-16

"Arm on tracks" refers to a variant of the robotic arm robot form factor in which the position of attachment of the robotic arm can also be moved around linearly or with more degrees of freedom.

E.g.:

Polymorphism (materials science) by

Ciro Santilli 37 Updated 2025-07-16

TODO definition. Appears to be isomers

Example:

the three most table polymorphs of calcium carbonate polymorphs are: