Deletionism Updated +Created
The problem of deletionism is that it removes users' confidence that their precious data will be safe. It's almost like having a database that constantly resets itself. Who will be willing to post on a website that deletes the content they created for free half of the time thus wasting people's precious time?
Democracy Updated +Created
Derivation of the Klein-Gordon equation Updated +Created
The Klein-Gordon equation directly uses a more naive relativistic energy guess of squared.
But since this is quantum mechanics, we feel like making into the "momentum operator", just like in the Schrödinger equation.
But we don't really know how to apply the momentum operator twice, because it is a gradient, so the first application goes from a scalar field to the vector field, and the second one...
So we just cheat and try to use the laplace operator instead because there's some squares on it:
But then, we have to avoid taking the square root to reach a first derivative in time, because we don't know how to take the square root of that operator expression.
So the Klein-Gordon equation just takes the approach of using this squared Hamiltonian instead.
Since it is a Hamiltonian, and comparing it to the Schrödinger equation which looks like:
taking the Hamiltonian twice leads to:
We can contrast this with the Dirac equation, which instead attempts to explicitly construct an operator which squared coincides with the relativistic formula: derivation of the Dirac equation.
Derivation of the Schrodinger equation Updated +Created
Derivative Updated +Created
The derivative of a function gives its slope at a point.
More precisely, it give sthe inclination of a tangent line that passes through that point.
Determinant Updated +Created
Name origin: likely because it "determines" if a matrix is invertible or not, as a matrix is invertible iff determinant is not zero.
Deterministic perfect information board game Updated +Created
Developmental biology Updated +Created
Video 1.
Where is Anatomy Encoded in Living Systems? by Michael Levin (2022)
Source.
  • we are very far from full understanding. End game is a design system where you draw the body and it compiles the DNA for you.
  • some cool mentions of regeneration
Developmental genetics Updated +Created
How genes form bodies.
Video 1.
Developmental Genetics 1 by Joseph Ross (2020)
Source. Talks about homeobox genes.
Dharma name Updated +Created
法 (fa3) is the Chinese name for Dharma, and sometimes used as a way short way to refer to Buddhism.
Diamond Sutra Updated +Created
Differentiable manifold Updated +Created
TODO find a concrete numerical example of doing calculus on a differentiable manifold and visualizing it. Likely start with a boring circle. That would be sweet...
Diffie-Hellman key exchange Updated +Created
Based on the fact that we don't have a P algorithm for the discrete logarithm of the cyclic group as of 2020, but we do have an efficient algorithm for modular exponentiation. But nor do we have proof that one does not exist! Living on the edge as usual for public-key cryptography.
DigitalDreamDoor Updated +Created
Ahh, this brings good memories of Ciro Santilli's musical formative teenage years scouring the web for the best art humanity had ever produced in certain generes. And it still is a valuable resource as of the 2020's!
Digital electronic circuit Updated +Created
Digital Light Processing Updated +Created
Dilution refrigerator Updated +Created
Video 1.
This Is What A Helium Dilution refrigerator Is by Dietterich Labs (2019)
Source.

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