67 ideas
| 8868 | Objective truth arises from interpersonal communication [Davidson] |
| Full Idea: The source of the concept of objective truth is interpersonal communication. | |
| From: Donald Davidson (Three Varieties of Knowledge [1991], p.209) | |
| A reaction: This is a distinctively Davidsonian idea, arising out of Wittgenstein's Private Language Argument. We could go a step further, and just say that 'objectivity is a social concept'. Davidson more or less pleads guilty to pragmatism in this essay. |
| 18405 | A 'teepee' argument has several mutually supporting planks to it [Cappelen/Dever] |
| Full Idea: In a 'teepee' argument, a number of argumentative planks intersupport each other. No plank is sufficiently strong to establish the position, but each lends credibility to the others because there is the appearance of a unified phenomenon. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 01.5) | |
| A reaction: To attack it, they say, you have to identify the separate planks of the argument. It is a moot point whether the teepee might be so imprecise that it is better described as 'coherence'. There is a background support, as well as the planks. |
| 8867 | A belief requires understanding the distinctions of true-and-false, and appearance-and-reality [Davidson] |
| Full Idea: Having a belief demands in addition appreciating the contrast between true belief and false, between appearance and reality, mere seeming and being. | |
| From: Donald Davidson (Three Varieties of Knowledge [1991], p.209) | |
| A reaction: This sets the bar very high for belief (never mind knowledge), and seems to imply that animals don't have beliefs. How should we describe their cognitive states then? I would say these criteria only apply to actual knowledge. |
| 10347 | Objectivity is intersubjectivity [Davidson] |
| Full Idea: An entity is objective in so far as it is intersubjective. | |
| From: Donald Davidson (Three Varieties of Knowledge [1991]), quoted by Martin Kusch - Knowledge by Agreement Ch.10 | |
| A reaction: This thought baffled me until I saw it in the context of socialised epistemology. Effectively objectivity is subsumed under justification, which in turn is seen in a social context, not private to individuals. |
| 8866 | If we know other minds through behaviour, but not our own, we should assume they aren't like me [Davidson] |
| Full Idea: If the mental states of others are known only through their behavioral and other outward manifestations, while this is not true of our own mental states, why should we think our own mental states are anything like those of others? | |
| From: Donald Davidson (Three Varieties of Knowledge [1991], p.207) | |
| A reaction: His point is that if you seriously doubt other minds, you should follow through on the implications. But that is to treat it as a theory about other minds, rather an a sceptical worry. Descartes didn't walk into walls while writing Meditation 1. |
| 10346 | Knowing other minds rests on knowing both one's own mind and the external world [Davidson, by Dummett] |
| Full Idea: Davidson argues that knowledge of other minds presupposes knowledge of one's own mind, and that there is no knowledge of other minds without knowledge of the external world. | |
| From: report of Donald Davidson (Three Varieties of Knowledge [1991]) by Michael Dummett - Common Sense and Physics Ch.10 | |
| A reaction: Davidson't argument is actually hard to swallow because it is so long and complex. Compressing the point makes it begin to sound like a variant of the argument from analogy. |
| 18422 | Prioprioception focuses on your body parts, not on your self, or indexicality [Cappelen/Dever] |
| Full Idea: Proprioception is not focused single-mindedly on the self, but is focused on a number of objects - the component bodily parts that belong to the self. There is no obvious need for a concept of the self, or of indexicality. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 07.2) |
| 18425 | We can acquire self-knowledge with mirrors, not just with proprioception and introspection [Cappelen/Dever] |
| Full Idea: Imagine a being that learns everything about itself by watching itself in mirrors, rather than by proprioception and introspection. Surely it can get wet in a storm, even though allegedly distinctive routes of self-knowledge are not available to it? | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 09.3) | |
| A reaction: [compressed] |
| 18421 | Proprioception is only immune from error if you are certain that it represents the agent [Cappelen/Dever] |
| Full Idea: The guarantee of immunity from error in prioprioception is only as strong as the guarantee that proprioception only ever represents the proprioceiving agent. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 07.1) | |
| A reaction: This is part of an interesting and sustained attack on the idea that self-knowledge is immune from error. They are thinking of science-fictiony situations where I am wired up to experience your leg movement. My experiences usually track me, that's all. |
| 18419 | Folk Functionalism is a Ramsification of our folk psychology [Cappelen/Dever] |
| Full Idea: According to Folk Functionalism, mental states are theoretically defined by Ramsifying on our folk-psychological theory. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 06.2) |
| 18404 | It is assumed that indexical content is needed to represent the perspective of perception [Cappelen/Dever] |
| Full Idea: Because our perceptual states typically represent the world as seen from a perspective, it is sometimes thought that some distinctively indexical kind of content is needed to characterise those states. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 01.4) | |
| A reaction: They are summarising this view precisely so that they can oppose it, and I think they are right. |
| 18426 | All information is objective, and purely indexical information is not much use [Cappelen/Dever] |
| Full Idea: Fundamentally, all information is objective information. ...[176] What we want is fully portable information, and information that co-ordinates on the world, rather than on us, is best suited for the task. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 10) | |
| A reaction: I agree entirely with their thesis. We just pick up information about ourselves, such as who and where we are, which is just like equivalent information about other people. It is isn't a special type of information. |
| 18427 | If some of our thought is tied to its context, it will be hard to communicate it [Cappelen/Dever] |
| Full Idea: It is bad news if some of our contents are essentially tied to particular contexts. ...If information needs to be assessed relative to some ur-context, later recipients won't know what to do with it. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 10) |
| 18428 | You don't remember your house interior just from an experienced viewpoint [Cappelen/Dever] |
| Full Idea: When you recall the look of the inside of your house ....where things are relative to one another is what persists in memory, not where they were relative to you when seen. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 10) | |
| A reaction: This seems to be a very telling example, though you could postulate some system which converts perspectival input into objective information. But why bother? We seek objective information, not perspectives. |
| 18429 | Our beliefs and desires are not organised around ourselves, but around the world [Cappelen/Dever] |
| Full Idea: Our view on the world is not primarily a view from a perspective. Our beliefs and desires are not organized around us. They are instead organized around the world itself. Our view is a view from everywhere. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 10) | |
| A reaction: Slipping in the claim that our desires are also organised around the world is not quite as persuasive as the claim about beliefs. If you want to draw a freehand straight line, focus on the far end of it. The world will guide your hand. |
| 18407 | Indexicality is not significantly connected to agency [Cappelen/Dever] |
| Full Idea: There are no interesting or distinctive explanatory connections between indexicality and agency. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 01.8) |
| 18413 | Fregeans can't agree on what 'senses' are [Cappelen/Dever] |
| Full Idea: There is little agreement among Fregeans about what senses are. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 04.5) | |
| A reaction: I don't take this to be sufficient grounds for dismissing Fregean senses. When we look into the workings of the linguistic mind, there seems little prospect of clarity or agreement. |
| 18417 | Possible worlds accounts of content are notoriously coarse-grained [Cappelen/Dever] |
| Full Idea: Possible worlds accounts of content are notoriously coarse-grained. They fail to distinguish between logical or mathematical truths, ..between metaphysical equivalences, ..between coreferentials, ..and between indexicals and non-indexicals. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 05.5) | |
| A reaction: [A nice summary, very compressed] |
| 18408 | Indexicals are just non-constant in meaning, and don't involve any special concepts [Cappelen/Dever] |
| Full Idea: Once the non-constant characters of expressions has been characterised, there is no further need for additional devices like 'first-person concepts' or 'demonstrative concepts'. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 01.7) | |
| A reaction: This seems to me to be a wonderfully liberating attack on this issue. There is a kind of creepy mysticism that has been allowed to accrue around indexicals, and it's nonsense. |
| 18414 | Fregeans say 'I' differs in reference, so it must also differ in sense [Cappelen/Dever] |
| Full Idea: Fregeans tend to treat as a fundamental tenet that sense determines reference; same sense, same reference. From that it follow trivially that indexicals don't have the same sense: different uses of 'I' have different referents, so sense must differ. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 04.6) | |
| A reaction: Interesting. Since it seems implausible that 'I' is profoundly different when two people use it, this seems to be a strong argument against Frege's distinction. But I rather like Frege's distinction, while being sceptical about 'I', so I'm baffled.... |
| 18423 | All indexicals can be expressed non-indexically [Cappelen/Dever] |
| Full Idea: Whatever can be expressed indexically could be expressed by non-indexical means. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 08.1) | |
| A reaction: This is the best summary of the thesis of their book. Indexicality in non-essential. |
| 8870 | Content of thought is established through communication, so knowledge needs other minds [Davidson] |
| Full Idea: Until a baseline has been established by communication with someone else, there is no point is saying one's own thoughts have a propositional content. Hence knowledge of another mind is essential all thought and all knowledge. | |
| From: Donald Davidson (Three Varieties of Knowledge [1991], p.213) | |
| A reaction: This really is building a skyscraper on the slightly shaky claims of the Private Language Argument (e.g. Idea 4158). Animals are so important in discussions of this kind. Is an albatross more or less devoid of thought and belief? |
| 18406 | The basic Kaplan view is that there is truth-conditional content, and contextual character [Cappelen/Dever] |
| Full Idea: In what we label 'Basic Kaplanianism', each of the sentences 'Smith is happy' and 'I am happy', as uttered by Smith, has two levels of meaning. The 'content' is a truth-conditional representation. The 'character' is a function from contexts to contents. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 01.6) | |
| A reaction: They give this as a minimal and plausible account of the situation, without reading huge significance into the indexical. I'm inclined to see the situation in terms of the underlying proposition containing both ingredients. |
| 18411 | It is proposed that a huge range of linguistic items are context-sensitive [Cappelen/Dever] |
| Full Idea: An enormous amount has been written about whether 'all', 'know', 'might', 'delicious', 'good', 'if, then', 'and', 'red', 'just', 'justified', 'probable', 'local', 'ready', and 'left-right' are context-sensitive. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 02.3) | |
| A reaction: The clearest way to approach these things is ask what the (informal) domain of quantification is for that particular context. The domain can shift in the course of a sentence. |
| 8869 | The principle of charity attributes largely consistent logic and largely true beliefs to speakers [Davidson] |
| Full Idea: Concerning charity, the Principle of Coherence seeks logical consistency in the thought of the speaker, and the Principle of Correspondence seeks a similar response to features of the world to that of an interpreter. The speaker has logic and true belief. | |
| From: Donald Davidson (Three Varieties of Knowledge [1991], p.211) | |
| A reaction: Davidson adds a Kantian commitment to pure and universal reason to the very sceptical framework created by Quine. I agree with Davidson, but it seems more like faith than like an argument or an empirical observation. |
| 18420 | We deny that action involves some special class of beliefs [Cappelen/Dever] |
| Full Idea: Maybe there is a class of beliefs that plays a special role in the explanation of action. We have argued against the existence of such a class (or at least any interesting such class). | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 06.2) | |
| A reaction: The main class which has been proposed is the one that involves indexical beliefs. I agree with this idea. |
| 21167 | Gravity is unusual, in that it always attracts and never repels [New Sci.] |
| Full Idea: Gravity is an odd sort of force, not least because it only ever works one way. Electromagnetism attracts and repels, but with gravity there are only positive masses always attract. | |
| From: New Scientist writers (Why the Universe Exists [2017], 05) | |
| A reaction: This leads to speculation about anti-gravity, but there is no current evidence for it. |
| 21176 | In the Big Bang general relativity fails, because gravity is too powerful [New Sci.] |
| Full Idea: At the origin of the universe gravity becomes so powerful that general relativity breaks down, giving infinity for every answer. | |
| From: New Scientist writers (Why the Universe Exists [2017], 09) |
| 21147 | Quantum electrodynamics incorporates special relativity and quantum mechanics [New Sci.] |
| Full Idea: The theory of electromagnetism that incorporates both special relativity and quantum mechanics is quantum electrodynamics (QED). It was developed by Dirac and others, and perfected in the 1940s. The field is a collection of quanta. | |
| From: New Scientist writers (Why the Universe Exists [2017], 02) | |
| A reaction: This builds on Maxwell's earlier classical theory. QED is said to be the best theory in all of physics. |
| 21155 | Photons have zero rest mass, so virtual photons have infinite range [New Sci.] |
| Full Idea: Photons, the field quanta of the electromagnetic force, have zero rest mass, so virtual photons can exist indefinitely and travel any distance, meaning the electromagnetic force has an infinite range. | |
| From: New Scientist writers (Why the Universe Exists [2017], 02) |
| 21161 | In the standard model all the fundamental force fields merge at extremely high energies [New Sci.] |
| Full Idea: The standard model says that the fields of all fundamental forces should merge at extremely high energies, meaning there is also a unified, high-energy field out there. | |
| From: New Scientist writers (Why the Universe Exists [2017], 03) | |
| A reaction: Not quite sure what 'out there' means. This idea is linked to the quest for dark energy. Is this unified phenomenon only found near the Big Bang? |
| 21146 | Electrons move fast, so are subject to special relativity [New Sci.] |
| Full Idea: Electrons in atoms move at high speeds, so they are subject to the special theory of relativity. | |
| From: New Scientist writers (Why the Universe Exists [2017], 02) | |
| A reaction: Presumably this implies a frame of reference, and defining velocities relative to other electrons. Plus time-dilation? |
| 21148 | The strong force is repulsive at short distances, strong at medium, and fades at long [New Sci.] |
| Full Idea: Experiments show that the nuclear binding force does not follow the inverse square law, but is repulsive at the shortest distances, then attractive, then fades away rapidly as distance increases further. | |
| From: New Scientist writers (Why the Universe Exists [2017], 02) | |
| A reaction: So how does it know when to be strong? Magnetism doesn't vary according to distance, and light obeys the inverse square law, because everything is decided at the output. - See 21151 for an explanation. It interacts after departure. |
| 21151 | Gluons, the particles carrying the strong force, interact because of their colour charge [New Sci.] |
| Full Idea: In QCD the particles that carry the strong force are called gluons. ...Gluons carry their own colour charges, so they can interact with each other (unlike photons) via the strong nuclear force (which limits the range of the force). | |
| From: New Scientist writers (Why the Universe Exists [2017], 02) | |
| A reaction: So the force varies in strength with distance because the degree of separation among the spreading gluons varies? The force has one range, which is squashed when close, effective at medium, and loses touch with distance? |
| 21152 | The strong force binds quarks tight, and the nucleus more weakly [New Sci.] |
| Full Idea: The strong force holds quarks together within protons and neutrons, and residual effects of the strong force bind protons (whch repel one another) and neutrons together in nuclei. | |
| From: New Scientist writers (Why the Universe Exists [2017], 02) | |
| A reaction: So the force is much stronger between quarks (which can't escape), and only 'residual' in the nucleus, which must be why smashing nuclei open is fairly easy, but smashin protons open needs higher energies. |
| 21142 | Classifying hadrons revealed two symmetry patterns, produced by three basic elements [New Sci.] |
| Full Idea: Classifying hadrons according to charge, strangeness and spin revealed patterns of eight and ten particles (SU(3) symmetery). The mathematics then showed that these are built from a basic group of only three members. | |
| From: New Scientist writers (Why the Universe Exists [2017], 01) |
| 21143 | Quarks in threes can build hadrons with spin ½ or with spin 3/2 [New Sci.] |
| Full Idea: Quarks in threes can build hadrons with spin ½ (proton, duu; neutron, ddu; lambda, dus), or with spin 3/2 (omega-minus, sss). | |
| From: New Scientist writers (Why the Universe Exists [2017], 01) |
| 21150 | Three different colours of quark (as in the proton) can cancel out to give no colour [New Sci.] |
| Full Idea: Just as mixing three colours of light gives white, so the three colour charges of quarks can add up to give no colour. This is what happens in the proton, which always contains one blue-charge quark, one red and one green. | |
| From: New Scientist writers (Why the Universe Exists [2017], 02) |
| 21145 | The four fundamental forces (gravity, electromagnetism, weak and strong) are the effects of particles [New Sci.] |
| Full Idea: There are four fundamental forces: gravity, electromagnetism, and the weak and strong nuclear forces. Particle physics has so far failed to encompass the force of gravity. The forces that shape our world are themselves the effect of particles. | |
| From: New Scientist writers (Why the Universe Exists [2017], 02) | |
| A reaction: Philosophers must take note of the fact that forces are the effects of particles. Common sense pictures forces imposed on particles, like throwing a tennis ball, but the particles are actually the sources of force. The gravitino is speculative. |
| 21153 | The weak force explains beta decay, and the change of type by quarks and leptons [New Sci.] |
| Full Idea: The beta decay of the neutron (into a proton, an electron and an antineutrino) can be described in terms of the weak force, which is 10,000 times weaker than the strong force. It allows the quarks and leptons to change from one type to another. | |
| From: New Scientist writers (Why the Universe Exists [2017], 02) | |
| A reaction: This seems to make it the key source of radioactivity. Perhaps it should be called the Force of Change? |
| 21154 | Three particles enable the weak force: W+ and W- are charged, and Z° is not [New Sci.] |
| Full Idea: The quantum field theory of the weak force needs three carrier particles. The W+ and W- are electrically charged, and enable the weak force to change the charge of a particle. The Z° is uncharged, and mediates weak interactions with no charge change. | |
| From: New Scientist writers (Why the Universe Exists [2017], 02) |
| 21156 | The weak force particles are heavy, so the force has a short range [New Sci.] |
| Full Idea: The W and Z particles are heavy, and so cannot travel far from their parents. The weak force therefore has a very short range. | |
| From: New Scientist writers (Why the Universe Exists [2017], 02) |
| 21164 | Why do the charges of the very different proton and electron perfectly match up? [New Sci.] |
| Full Idea: Why do the proton and electron charges mirror each other so perfectly when they are such different particles? | |
| From: New Scientist writers (Why the Universe Exists [2017], 04) | |
| A reaction: We seem to have reached a common stage in science, where we have a wonderful descriptive model (the Standard Model), but we cannot explain why what is modelled is the way it is. |
| 21170 | The Standard Model cannot explain dark energy, survival of matter, gravity, or force strength [New Sci.] |
| Full Idea: The standard model cannot explain dark matter, or dark energy (which is causing expansion to accelerate). It cannot explain how matter survived annihilation with anti-matter in the Big Bang, or explain gravity. The strength of each force is unexplained. | |
| From: New Scientist writers (Why the Universe Exists [2017], 06) | |
| A reaction: [compressed] P.141 adds that the model has to be manipulated to keep the Higgs mass low enough. |
| 21140 | Spin is a built-in ration of angular momentum [New Sci.] |
| Full Idea: Spin is a built-in ration of angular momentum. | |
| From: New Scientist writers (Why the Universe Exists [2017], 01) | |
| A reaction: As an outsider all I can do is collect descriptions of such properties from the experts. The experts appear to be happy with the numbers inserted in the equations. |
| 21149 | Quarks have red, green or blue colour charge (akin to electric charge) [New Sci.] |
| Full Idea: Quarks have a property akin to electric charge, called their colour charge. It comes in three varieties, red, green and blue. | |
| From: New Scientist writers (Why the Universe Exists [2017], 02) |
| 21158 | Fermions, with spin ½, are antisocial, and cannot share quantum states [New Sci.] |
| Full Idea: Particles with half-integer spin, such as electrons, protons or quarks (all spin ½) have an asymmetry in their wavefunction that makes them antisocial. These particles (Fermions) cannot share a quantum state. | |
| From: New Scientist writers (Why the Universe Exists [2017], 02) | |
| A reaction: This is said to explain the complexity of matter, with carbon an especially good example. |
| 21165 | Spin is akin to rotation, and is easily measured in a magnetic field [New Sci.] |
| Full Idea: Spin is a quantum-mechanical property of a particle akin to rotation about its own axis. Particles of different spins respond to magnetic fields in different ways, so it is a relatively easy thing to measure. | |
| From: New Scientist writers (Why the Universe Exists [2017], 04) | |
| A reaction: I wish I knew what 'akin to' meant. Maybe particles are not rigid bodies, so they cannot spin in the way a top can? It must be an electro-magnetic property. Idea 21166 says spin has two possible directions. |
| 21157 | Particles are spread out, with wave-like properties, and higher energy shortens the wavelength [New Sci.] |
| Full Idea: Particles obeying the laws of quantum mechanics have wave-like properties - moving as a quantum wave-function, spread out in space, with wavelengths that get shorter as their energy increases. | |
| From: New Scientist writers (Why the Universe Exists [2017], 02) | |
| A reaction: Thus X-rays are dangerous, but long wave radio is not. De Broglie's equation. |
| 21163 | The mass of protons and neutrinos is mostly binding energy, not the quarks [New Sci.] |
| Full Idea: Most of a proton's or neutrino's mass is contained in the interaction energies of a 'sea' of quarks, antiquarks and gluons that bind them. ...You might feel solid, but in fact you're 99 per cent binding energy. | |
| From: New Scientist writers (Why the Universe Exists [2017], 04) | |
| A reaction: This is because energy is equivalent to mass (although gluons are said to have energy but no mass - puzzled by that). This is a fact which needs a bit of time to digest. Once you've grasped we are full of space, you still have understood it. |
| 21168 | Gravitional mass turns out to be the same as inertial mass [New Sci.] |
| Full Idea: There are two types of mass: gravitational mass quantifies how strongly an object feels gravity, while inertial mass quantifies an object's resistance to acceleration. There proven equality is at the heart of General Relativity. | |
| From: New Scientist writers (Why the Universe Exists [2017], 05) | |
| A reaction: It had never occurred to me that these two values might come apart. Doesn't their identical values demonstrate that they are in fact the same thing? Sounds like Hesperus/Phosphorus to me. The book calls it 'mysterious'. |
| 21138 | Neutrons are slightly heavier than protons, and decay into them by emitting an electron [New Sci.] |
| Full Idea: The proton (938.3 MeV) is lighter than the neutron (939.6 MeV) and does not decay, but the heavier neutron can change into a proton by emitting an electron. (If you gather a bucketful of neutrons, after ten minutes only half of them would be left). | |
| From: New Scientist writers (Why the Universe Exists [2017], 01) | |
| A reaction: Protons are more or less eternal, but some theories have them decaying after billions of years. Smashing protons together is a popular pastime for physicists. |
| 21144 | Top, bottom, charm and strange quarks quickly decay into up and down [New Sci.] |
| Full Idea: Quarks can change from one variety to another, and the top, bottom, charm and strange quarks all rapidly decay to the up and down quarks of everyday life. | |
| From: New Scientist writers (Why the Universe Exists [2017], 01) | |
| A reaction: Hence the universe is largely composed of up and down quarks and electrons. The other quarks seem to be more important in the early universe. |
| 21141 | Neutrinos were proposed as the missing energy in neutron beta decay [New Sci.] |
| Full Idea: When a neutron decays into a proton and an electron (one example of beta decay), the energy of the two particles adds up to less than the starting energy of the neutron. Pauli and Fermi concluded that a neutrino (an electron antineutrino) is emitted. | |
| From: New Scientist writers (Why the Universe Exists [2017], 01) | |
| A reaction: I'm wondering how much they could infer about the nature of the new particle (which was only confirmed 26 years later). |
| 21169 | Only neutrinos spin anticlockwise [New Sci.] |
| Full Idea: Neutrinos are the only particles that seem just to spin anticlockwise. | |
| From: New Scientist writers (Why the Universe Exists [2017], 06) | |
| A reaction: See 21166. Anti-neutrino spin is the opposite way. Which way up do you hold the neutrino when pronouncing that it is 'anticlockwise? |
| 21166 | Standard antineutrinos have opposite spin and opposite lepton number [New Sci.] |
| Full Idea: In the conventional standard model neutrinos have antiparticles - which spin in the opposite direction, and have the opposite lepton number. | |
| From: New Scientist writers (Why the Universe Exists [2017], 05) |
| 21171 | The symmetry of unified electromagnetic and weak forces was broken by the Higgs field [New Sci.] |
| Full Idea: In the very early hot universe the electromagnetic and weak nuclear forces were one. The early emergence of the Higgs field led to electroweak symmetry breaking. The W and Z bosons grew fat, and the photon raced away mass-free. | |
| From: New Scientist writers (Why the Universe Exists [2017], 07) |
| 21179 | Supersymmetric string theory can be expressed using loop quantum gravity [New Sci.] |
| Full Idea: String theory, together with its supersymmetric particles, has recently been rewritten in the space-time described by loop quantum gravity (which says that space-time ust be made from finite chunks). | |
| From: New Scientist writers (Why the Universe Exists [2017], 09) |
| 21178 | String theory is now part of 11-dimensional M-Theory, involving p-branes [New Sci.] |
| Full Idea: String theory has now been incorporated into Ed Witten's M-Theory, which is a mathematical framework that lives in 11-dimensional space-time, involving higher-dimensional objects called p-branes, of which strings are a special case. | |
| From: New Scientist writers (Why the Universe Exists [2017], 09) |
| 21175 | String theory might be tested by colliding strings to make bigger 'stringballs' [New Sci.] |
| Full Idea: A future accelerator might create 'stringballs', when two strings slam into one another and, rather than combining to form a stretched string, make a tangled ball. Finding them would prove string theory. | |
| From: New Scientist writers (Why the Universe Exists [2017], 08) | |
| A reaction: This is the only possible test for string theory which I have seen suggested. How do you 'slam strings together'? |
| 21177 | String theory offers a quantum theory of gravity, by describing the graviton [New Sci.] |
| Full Idea: String theory works as a quantum theory of gravity because string vibrations can describe gravitons, the hypothetical carriers of the gravitational force. | |
| From: New Scientist writers (Why the Universe Exists [2017], 09) | |
| A reaction: Presumably the main aim of a quantum theory of gravity is to include gravitons within particle theory. This idea has to be a main attraction of string theory. Compare Idea 21166. |
| 21162 | Only supersymmetry offers to incorporate gravity into the scheme [New Sci.] |
| Full Idea: Peter Higgs says he is a fan of supersymmetry, largely because it seems to be the only route by which gravity can be brought into the scheme. | |
| From: New Scientist writers (Why the Universe Exists [2017], 03) | |
| A reaction: Peter Higgs proposed the Higgs boson (now discovered). This seems a very good reason to favour supersymmetry. A grand unified theory that left out gravity doesn't seem to be unified quite grandly enough. |
| 21159 | Supersymmetry has extra heavy bosons and heavy fermions [New Sci.] |
| Full Idea: Supersymmetry posits heavy boson partners for all fermions, and heavy fermions for all bosons. | |
| From: New Scientist writers (Why the Universe Exists [2017], 02) | |
| A reaction: The main Fermions are electron, proton and quark. Do extra bosons imply extra forces? Peter Higgs favours supersymmetry. |
| 21173 | Supersymmetry says particles and superpartners were unities, but then split [New Sci.] |
| Full Idea: The key to supersymmetry is that in the high-energy soup of the early universe, particles and their superpartners were indistinguishable. Each pair existed as single massless entities. With expansion and cooling this supersymmetry broke down. | |
| From: New Scientist writers (Why the Universe Exists [2017], 08) |
| 21172 | The evidence for supersymmetry keeps failing to appear [New Sci.] |
| Full Idea: The old front-runner theory, supersymmetry, has fallen from grace as the Large Hadron Collider keeps failing to find it. | |
| From: New Scientist writers (Why the Universe Exists [2017], 07) |
| 21160 | The Higgs field means even low energy space is not empty [New Sci.] |
| Full Idea: The point about the Higgs field is that even the lowest-energy state of space is not empty. | |
| From: New Scientist writers (Why the Universe Exists [2017], 02) | |
| A reaction: So where is the Higgs field located? Even if there is no utterly empty space, the concept of location implies a concept of space more basic than the fields (about 16, I gather) which occupy it. You can't describe movement without a concept of location. |
| 21174 | Dark matter must have mass, to produce gravity, and no electric charge, to not reflect light [New Sci.] |
| Full Idea: Whatever dark matter is made of, it must have mass to feel and generate gravity; but no electric charge, so it does not interact with light. The leading candidate has been the weakly interacting massive particle (WIMP), much heavier than a proton. | |
| From: New Scientist writers (Why the Universe Exists [2017], 08) | |
| A reaction: Note that it must 'generate' gravity. The idea of a law of gravity which is externally imposed on matter is long dead. Heavy WIMPs have not yet been detected. |