26 ideas
| 13338 | '"It is snowing" is true if and only if it is snowing' is a partial definition of the concept of truth [Tarski] |
| 13337 | A language: primitive terms, then definition rules, then sentences, then axioms, and finally inference rules [Tarski] |
| 13335 | Semantics is the concepts of connections of language to reality, such as denotation, definition and truth [Tarski] |
| 13336 | A language containing its own semantics is inconsistent - but we can use a second language [Tarski] |
| 13339 | A sentence is satisfied when we can assert the sentence when the variables are assigned [Tarski] |
| 13340 | Satisfaction is the easiest semantical concept to define, and the others will reduce to it [Tarski] |
| 13341 | Using the definition of truth, we can prove theories consistent within sound logics [Tarski] |
| 20624 | Work degrades into heat, but not vice versa [Close] |
| 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] |
| 20622 | All motions are relative and ambiguous, but acceleration is the same in all inertial frames [Close] |
| 20628 | The electric and magnetic are tightly linked, and viewed according to your own motion [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] |
| 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] |
| 20641 | Electrons get their mass by interaction with the Higgs field [Close] |
| 20631 | Dirac showed how electrons conform to special relativity [Close] |
| 20626 | Modern theories of matter are grounded in heat, work and energy [Close] |
| 20633 | The Higgs field is an electroweak plasma - but we don't know what stuff it consists of [Close] |
| 20640 | Space-time is indeterminate foam over short distances [Close] |
| 17366 | Virtually all modern views of speciation rest on relational rather than intrinsic features [Okasha] |