40 ideas
| 13913 | The four 'perfect syllogisms' are called Barbara, Celarent, Darii and Ferio [Engelbretsen/Sayward] |
| 13914 | Syllogistic logic has one rule: what is affirmed/denied of wholes is affirmed/denied of their parts [Engelbretsen/Sayward] |
| 13915 | Syllogistic can't handle sentences with singular terms, or relational terms, or compound sentences [Engelbretsen/Sayward] |
| 13916 | Term logic uses expression letters and brackets, and '-' for negative terms, and '+' for compound terms [Engelbretsen/Sayward] |
| 13850 | In modern logic all formal validity can be characterised syntactically [Engelbretsen/Sayward] |
| 13849 | Classical logic rests on truth and models, where constructivist logic rests on defence and refutation [Engelbretsen/Sayward] |
| 13851 | Unlike most other signs, = cannot be eliminated [Engelbretsen/Sayward] |
| 13852 | Axioms are ω-incomplete if the instances are all derivable, but the universal quantification isn't [Engelbretsen/Sayward] |
| 21202 | The strong force has a considerably greater range than the weak force [Martin,BR] |
| 20624 | Work degrades into heat, but not vice versa [Close] |
| 21211 | If an expected reaction does not occur, that implies a conservation law [Martin,BR] |
| 20623 | First Law: energy can change form, but is conserved overall [Close] |
| 20625 | Third Law: total order and minimum entropy only occurs at absolute zero [Close] |
| 20628 | The electric and magnetic are tightly linked, and viewed according to your own motion [Close] |
| 20622 | All motions are relative and ambiguous, but acceleration is the same in all inertial frames [Close] |
| 20635 | The general relativity equations relate curvature in space-time to density of energy-momentum [Close] |
| 20642 | Photon exchange drives the electro-magnetic force [Close] |
| 21209 | Electron emit and reabsorb photons, which create and reabsorb virtual electrons and positrons [Martin,BR] |
| 20627 | Electric fields have four basic laws (two by Gauss, one by Ampère, one by Faraday) [Close] |
| 20630 | Light isn't just emitted in quanta called photons - light is photons [Close] |
| 20637 | In general relativity the energy and momentum of photons subjects them to gravity [Close] |
| 20629 | Electro-magnetic waves travel at light speed - so light is electromagnetism! [Close] |
| 20632 | In QED, electro-magnetism exists in quantum states, emitting and absorbing electrons [Close] |
| 20639 | Quantum fields contain continual rapid creation and disappearance [Close] |
| 21212 | The Higgs field, unlike others, has a nozero value in a state without particles [Martin,BR] |
| 21201 | A 'field' is just a region to which points can be assigned in space and time [Martin,BR] |
| 20631 | Dirac showed how electrons conform to special relativity [Close] |
| 20641 | Electrons get their mass by interaction with the Higgs field [Close] |
| 21205 | Many physicists believe particles have further structure, if only we could see it [Martin,BR] |
| 21203 | Uncertainty allows very brief violations of energy conservation - even shorter with higher energies [Martin,BR] |
| 21207 | The Exclusion Principle says no two fermions occupy the same state, with the same numbers [Martin,BR] |
| 20626 | Modern theories of matter are grounded in heat, work and energy [Close] |
| 21204 | The standard model combines theories of strong interaction, and electromagnetic and weak interaction [Martin,BR] |
| 21208 | Eletrons don't literally 'spin', because they are point-like [Martin,BR] |
| 21210 | Virtual particles surround any charged particle [Martin,BR] |
| 21206 | The properties of a particle are determined by its quantum numbers and its mass [Martin,BR] |
| 20633 | The Higgs field is an electroweak plasma - but we don't know what stuff it consists of [Close] |
| 21213 | String theory only has one free parameter (tension) - unlike the standard model with 19 [Martin,BR] |
| 20640 | Space-time is indeterminate foam over short distances [Close] |
| 21200 | An 'element' is what cannot be decomposed by chemistry [Martin,BR] |