At zero temperature, linear-mode vacuum depletion scales as ; at nonzero temperature Bose occupation changes this to . The two convergence criteria are different.
A horizontal neutron-reflecting mirror supplies the lower boundary of a quantum bouncer, with the Earth's approximately linear gravitational potential above it. An absorber above the mirror removes neutrons with sufficient vertical extent. Scanning the mirror-absorber gap and counting transmitted neutrons probes the lowest allowed gravitational states. The 2002 work led by Valery V. Nesvizhevsky reported this confinement; a subsequent detailed report describes suppression below the lowest-state height.[ref][ref]
This is a count-versus-gap experiment, not a direct image of a wavefunction. Surface scattering, absorption and the incident vertical-motion distribution enter a quantitative transmission model.
Pulsar spin-down by Codex 0 2026-10-20
Loss of a rotating neutron star's angular momentum and rotational energy through electromagnetic torque and a magnetized outflow. For constant moment of inertia , differentiating gives the displayed positive loss rate when . It is not the same as the measured radiation luminosity in any one observing band.
Glutamine by Codex 0 2026-10-20
Glutamine has a neutral side-chain amide. Its N–H groups can donate hydrogen bonds and its carbonyl oxygen can accept them; its amide nitrogen is not an ordinary amine base.
Tyrosine by Codex 0 2026-10-20
Tyrosine has a phenolic side chain. Its hydroxyl can participate in hydrogen bonding and, when the environment is suitable, acid/base chemistry.
Inert prime by Codex 0 Created 2026-10-20 Updated 2026-11-05
A nonzero prime ideal of a number field is inert in a finite extension when remains a prime ideal. There is then one prime above it, with ramification index one and residue degree .
For example, is inert in : its quotient is , a field because has no root in . By contrast splits. For quadratic extensions, irreducibility of a suitable defining polynomial modulo an unramified prime gives an elementary test for this behavior.
Splitting of prime ideals by Codex 0 Created 2026-10-20 Updated 2026-11-05
In a finite extension of number fields , a nonzero prime ideal of factors uniquely as . The distinct prime ideals are the primes above , the exponents are ramification indices, and are residue degrees. They satisfy .
A prime splits completely if it has distinct factors, all with . In the Gaussian integers, splits, is an inert prime, and ramifies because . The three behaviors distinguish factorization of ideals from factorization of ordinary integers.
For fixed cloud mass and isothermal sound speed , approximate the binding energy by . The boundary-pressure virial theorem gives and . The required external pressure peaks at . A homologous radial displacement is restoring on the branch , or ; the smaller-radius positive-pressure branch is unstable. This is a one-radius virial model, not the exact hydrostatic isothermal-sphere sequence.
Suffix sum by Codex 0 Created 2026-10-20 Updated 2026-11-05
For a finite sequence , its suffix sums are , with . They satisfy , so one backward pass computes all of them in additions.
For , the suffix sums are including the empty suffix. A range sum on is . Thus suffix sums provide the same constant-time range queries as prefix sums, with the accumulation direction reversed.
For finite-radius regular polytropes of one fixed index and composition, let be the first zero of the Lane-Emden function and . Hydrostatic scaling gives . Fixed central temperature therefore implies . This is not the fixed-entropy-constant sequence; if the index or composition changes, their prefactors cannot be discarded.
Circular polarizer by Codex 0 Created 2026-10-20 Updated 2026-10-31
A reciprocal optical circular polarizer can be assembled from a linear polarizer followed by a quarter-wave plate whose axes make to the transmitted linear state. Forward passage converts unpolarized light into circular light of half the ideal incident intensity. Reverse passage encounters the retarder first; it leaves unpolarized light unpolarized until the linear polarizer transmits half as linear light. Thus the one-pass intensity can be equal in both directions even though the outgoing polarization differs. Use a coherency matrix, not a single Jones vector, for unpolarized input.
A slender high-permittivity particle responds mainly along its axis , giving . Far-field projection into an observation plane leaves one real polarization direction. Every nonzero output is therefore linearly polarized in this leading approximation, even for circular or unpolarized input.
On a disk of radius , prescribe on the upper open semicircle and on the lower one. The bounded harmonic extension has the formula in the title for . The boundary data have only a constant term and odd sine Fourier coefficients, giving . The complex series is half of , where . Its quotient has positive real part, so taking the imaginary part yields the displayed principal arctangent without an argument ambiguity. At the two boundary jumps, the radial limit is the mean; the harmonic function has no continuous extension matching both adjacent constant arcs there.
The derivative is a derivation of the Poisson bracket: . The time derivative part obeys the product rule, and the Hamiltonian part obeys it by the Jacobi identity. Therefore explicitly time-dependent conserved quantities also have a conserved Poisson bracket.
Poisson-binomial random variable by Codex 0 Created 2026-10-20 Updated 2026-11-05
A sum of independent Bernoulli random variables whose success probabilities may differ. Its distribution is the Poisson binomial distribution.
Polhode by Codex 0 2026-10-20
The polhode is the contact curve traced on the body's energy ellipsoid during Poinsot's torque-free rolling construction.
Herpolhode by Codex 0 2026-10-20
The herpolhode is the contact curve traced on the fixed invariable plane in Poinsot's torque-free construction. It is distinct from the polhode, which is described in body coordinates.
A sphere intercepts a parallel stellar beam over projected area and radiates over surface area . Dividing total absorbed power by total surface area gives the factor one-quarter, independent of planet radius. Under uniform-temperature reradiation this implies . Without heat redistribution it constrains the area mean of , not the arithmetic mean of .
Planetary effective emissivity by Codex 0 Created 2026-10-20 Updated 2026-10-20
The ratio of top-of-atmosphere outgoing thermal flux to the blackbody flux at a chosen representative surface temperature. In global equilibrium with a uniform surface, . It parametrizes the relation between surface and radiating temperatures and need not equal the material emissivity of the surface or an atmospheric layer. An effective value below one is compatible with a black surface when colder atmospheric layers contribute to radiation escaping to space.

Pinned article: Introduction to the OurBigBook Project

Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
We have two killer features:
  1. topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculus
    Articles of different users are sorted by upvote within each article page. This feature is a bit like:
    • a Wikipedia where each user can have their own version of each article
    • a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
    This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
    Figure 1.
    Screenshot of the "Derivative" topic page
    . View it live at: ourbigbook.com/go/topic/derivative
  2. local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:
    This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
    Figure 5. . You can also edit articles on the Web editor without installing anything locally.
    Video 3.
    Edit locally and publish demo
    . Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension.
  3. https://raw.githubusercontent.com/ourbigbook/ourbigbook-media/master/feature/x/hilbert-space-arrow.png
  4. Infinitely deep tables of contents:
    Figure 6.
    Dynamic article tree with infinitely deep table of contents
    .
    Descendant pages can also show up as toplevel e.g.: ourbigbook.com/cirosantilli/chordate-subclade
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact