Spanish (language) Updated 2025-07-16
University should focus on inspiring and not on evaluating Updated 2025-07-16
As of 2020s and much earlier, Ciro Santilli believes that undergrad studies were fundamentally broken (considering the Information Age which completely changed what would be possible) because university had only two goals, with the exception of a few enlightened professors:As a result, most students, who would not go on to do a PhD essentially do a simple trade: all their time, and possibly some money, in exchange for imbuing themselves with the incredible name of a respected institution so they can get better jobs later on.
- rank students from worse to best so they can get into PhD programs.For regular jobs grades didn't even matter as much compared the prestige of your university (and therefore, university entry exam grades) and your ability to stand the stress of exams to get minimal passing grade.In particular, being able to rank requires setting the difficulty level at a point where you can see a normal distribution in grades, and not have everyone at either 0 nor 100%.
- get money from the students. Of course, in countries where university is "free", this means reporting how many students you had to some government office so they can give you a corresponding budget. But you still have an incentive to enroll as many as possible.
2008 Nobel Prize in Chemistry Updated 2025-07-16
For the discovery of green fluorescent protein.
Construction and management simulation Updated 2025-07-16
Cycling Updated 2025-07-16
E notation Updated 2025-07-16
What do you prefer,
1 \times 10^{10}
or 1E10
. Singularity Updated 2025-07-16
Software quality assurance Updated 2025-07-16
Solid-state physics Updated 2025-07-16
Source code Updated 2025-07-16
Terminal emulator Updated 2025-07-16
3D file format Updated 2025-07-16
www.threekit.com/blog/gltf-everything-you-need-to-know comparision of several formats
Book by Abraham Pais Updated 2025-07-16
Good television series Updated 2025-07-16
Piezoelectric actuator Updated 2025-07-16
Quartz Updated 2025-07-16
Piezoelectric, and notably used in quartz clock.
Unitary matrix Updated 2025-07-16
Complex analogue of orthogonal matrix.
Applications:
- in quantum computers programming basically comes down to creating one big unitary matrix as explained at: quantum computing is just matrix multiplication
Volume of the parallelepiped Updated 2025-07-16
Autodidacticism Updated 2025-07-16
There are two types of people:
- those who are autodidacts
- those who didn't really learn
Some possible definitions:
Thus OurBigBook.com.
Why do symmetries such as SU(3), SU(2) and U(1) matter in particle physics? Updated 2025-07-16
Physicists love to talk about that stuff, but no one ever has the guts to explain it into enough detail to show its beauty!!!
Perhaps the wisest thing is to just focus entirely on the part to start with, which is the quantum electrodynamics one, which is the simplest and most useful and historically first one to come around.
Perhaps the best explanation is that if you assume those internal symmetries, then you can systematically make "obvious" educated guesses at the interacting part of the Standard Model Lagrangian, which is the fundamental part of the Standard Model. See e.g.:
- derivation of the quantum electrodynamics Lagrangian
- Physics from Symmetry by Jakob Schwichtenberg (2015) chapter 7 "Interaction Theory" derives all three of quantum electrodynamics, weak interaction and quantum chromodynamics Lagrangian from each of the symmetries!
Notably, axelmaas.blogspot.com/2010/08/global-and-local-symmetries.html gives a good overview:so it seems that that's why they are so key: local symmetries map to the forces themselves!!!
A local symmetry transformation is much more complicated to visualize. Take a rectangular grid of the billiard balls from the last post, say ten times ten. Each ball is spherical symmetric, and thus invariant under a rotation. The system now has a global and a local symmetry. A global symmetry transformation would rotate each ball by the same amount in the same direction, leaving the system unchanged. A local symmetry transformation would rotate each ball about a different amount and around a different axis, still leaving the system to the eye unchanged. The system has also an additional global symmetry. Moving the whole grid to the left or to the right leaves the grid unchanged. However, no such local symmetry exists: Moving only one ball will destroy the grid's structure.Such global and local symmetries play an important role in physics. The global symmetries are found to be associated with properties of particles, e. g., whether they are matter or antimatter, whether they carry electric charge, and so on. Local symmetries are found to be associated with forces. In fact, all the fundamental forces of nature are associated with very special local symmetries. For example, the weak force is actually associated in a very intricate way with local rotations of a four-dimensional sphere. The reason is that, invisible to the eye, everything charged under the weak force can be characterized by a arrow pointing from the center to the surface of such a four-dimensional sphere. This arrow can be rotated in a certain way and at every individual point, without changing anything which can be measured. It is thus a local symmetry. This will become more clearer over time, as at the moment of first encounter this appears to be very strange indeed.
axelmaas.blogspot.com/2010/09/symmetries-of-standard-model.html then goes over all symmetries of the Standard Model uber quickly, including the global ones.
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