88 ideas
| 21757 | Philosophy is the conceptual essence of the shape of history [Hegel] |
| Full Idea: Philosophy is the supreme blossom - the concept - of the entire shape of history, the consciousness and the spiritual essence of the whole situation, the spirit of the age as the spirit present and aware of itself in thought. | |
| From: Georg W.F.Hegel (Lectures on the History of Philosophy [1830], p.25), quoted by Stephen Houlgate - An Introduction to Hegel 01 | |
| A reaction: This sees philosophy as intrinsically historical, which is a founding idea for 'continental' philosophy. Analysis is tied to science, in which the history of the subject is seen as irrelevant to its truth. Does this mean we can't go back to Aristotle? |
| 14562 | A process is unified as an expression of a collection of causal powers [Mumford/Anjum] |
| Full Idea: A process has a unity to it that comes from being the expression of a collection of causal powers. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 5.5 1) | |
| A reaction: I would be happier with this if I had a clear notion of what counts as a 'collection' of causal powers. We are back with the Leibnizian anguish over what constitutes a 'unity'. Processes need more attention, I'm thinking. |
| 14541 | Events are essentially changes; property exemplifications are just states of affairs [Mumford/Anjum] |
| Full Idea: Events are to be understood essentially as changes, rather than as property exemplifications. A particular exemplifying a property (as in Kim 1973 and Lewis 1986) would be better understood as a state of affairs. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 2.3) | |
| A reaction: I agree entirely with this. I've never been able to make sense of events as such static relations. It resembles the dubious Russellian view of motion as just being at one place and then at another. |
| 14553 | Weak emergence is just unexpected, and strong emergence is beyond all deduction [Mumford/Anjum] |
| Full Idea: We can say that a phenomenon is 'weakly emergent' when it is unexpected, and 'strongly emergent' when it is not deducible even in principle. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 4.3) | |
| A reaction: [compression of Chalmers 2006:244] I don't find emergence very interesting, since weak emergence surrounds us all day long, and is the glory of the world, and strong emergence is (I believe) nonsense. |
| 14538 | Powers explain properties, causes, modality, events, and perhaps even particulars [Mumford/Anjum] |
| Full Idea: Properties, causes, modality, events, and perhaps even particulars, can all be explained in terms of powers. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 1.2) | |
| A reaction: I love powers, but this may be optimistic. I take the concept of causation to be 'more' primitive than powers; how else could you even say what a power is? I presume something must exist to have the power, which gives you particulars. |
| 14555 | Powers offer no more explanation of nature than laws do [Mumford/Anjum] |
| Full Idea: In respect of explanation the powers view does little better than the laws view. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 4.3c) | |
| A reaction: Quite so. Powers are primitive, so they offer no elucidation of nature, but constitute the building blocks for explanations. Essences are, I think, clusters of powers, and the way in which they cluster is where we find the explanations. |
| 14557 | Powers are not just basic forces, since they combine to make new powers [Mumford/Anjum] |
| Full Idea: Powers are not necessarily reducible to forces. ...That new powers can be found when others combine is a regular part of common sense. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 4.4) | |
| A reaction: [first bit p.102] Hm. I've always thought of powers as basic components of ontology. This idea implies that a herd of buffalo has a single power to flatten a tented village. An extra buffalo creates a completely new power. An awful lot of vague powers. |
| 14583 | Dispositionality is a natural selection function, picking outcomes from the range of possibilities [Mumford/Anjum] |
| Full Idea: Dispositionality can be understood as a sort of selection function - a natural one in this case - and picks out a limited number of outcomes from all the ones that the disposition is for. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 8.9) | |
| A reaction: Functions should strictly have one output. This sounds wrong. The disposition pushes its powers into the environment, but it is the surrounding contextual powers which do the selecting, in concert. No disposition does any selecting |
| 14536 | We say 'power' and 'disposition' are equivalent, but some say dispositions are manifestable [Mumford/Anjum] |
| Full Idea: We use the terms 'power' and 'disposition' as equivalent, but some reserve the term 'disposition' for powers that tend to be manifested. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 1.1) | |
| A reaction: [For the latter they cite Fara 2005] There is some point to the latter distinction, as separating those powers that relate to the actual world from those powers that could never be triggered in actuality. I would say a power produces a disposition. |
| 14584 | The simple conditional analysis of dispositions doesn't allow for possible prevention [Mumford/Anjum] |
| Full Idea: The most obvious inadequacy of the simple conditional account of dispositions is that it fails to accommodate the possibility of prevention. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 8.10) | |
| A reaction: [They cite Ryle 1949 for the original idea] The point is obviously correct, since the simple analysis assumes that the outcome occurred [∀x(Dx → (Sx → Mx)]. If the outcome was blocked (by finks or antidotes) the disposition would remain. |
| 14582 | Might dispositions be reduced to normativity, or to intentionality? [Mumford/Anjum] |
| Full Idea: There have been attempts to reduce dispositionality to normativity (by Lowe 1989) and to intentionality (by Molnar 1998). | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 8.8) | |
| A reaction: I don't really believe in something called 'normativity', and I think it is better to explain intentionality in terms of dispositions, rather than Molnar's way round (though intentionality of mind reveals the nature of powers rather well). |
| 14542 | If statue and clay fall and crush someone, the event is not overdetermined [Mumford/Anjum] |
| Full Idea: If both the statue and the clay fall on someone and crush them to death, we would not say that the death is overdetermined. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 2.7) | |
| A reaction: I don't need many reasons to give up the idea that the statue and the clay are two objects, but this will do nicely as one of them. |
| 14535 | Pandispositionalists say structures are clusters of causal powers [Mumford/Anjum] |
| Full Idea: A pandispositionalist has to defend the view that even a property such as sphericity is in reality a cluster of causal powers. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 1.1) | |
| A reaction: Is sphericity even a 'property'? I think 'feature' might be the best word for it. 'Quality' is quite good, but is too suggestive of qualia and secondary qualities. 'Mode' is not bad. Things have 'modes of existence' and 'powers'? Powers create modes. |
| 14561 | Perdurantism imposes no order on temporal parts, so sequences of events are contingent [Mumford/Anjum] |
| Full Idea: Perdurantism tends to go with the view that it is essentially contingent what follows what, because it is no part of the essence of temporal parts that they be arranged in any particular order. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 5.5 1) | |
| A reaction: Nice. There is nothing illogical, then, in elderly me intervening between childish me and middle-aged me. Essentialists like me must clearly oppose this view. Elderly me must be preceded and caused by middle-aged me. |
| 14579 | Dispositionality is the core modality, with possibility and necessity as its extreme cases [Mumford/Anjum] |
| Full Idea: We think dispositionality is the core modality from which the other two standard modal operators draw their sense as being limiting cases on a spectrum. ...This gives a very this-worldly account of possibility and necessity. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 8.5) | |
| A reaction: I'm strongly in favour of this-worldly accounts of modal truths, so I like this. They take dispositions to hover somewhere between what is barely possible and what is absolutely necessary. But is modality actually part of the physical world? |
| 14580 | Dispositions may suggest modality to us - as what might not have been, and what could have been [Mumford/Anjum] |
| Full Idea: Dispositionality could be what gives us the idea of there being modality in the first place: that what is might not be, and what is not could be. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 8.5) | |
| A reaction: Compare Williamson's suggestion that counterfactual thinking is the source of such things, which is a similar thought. I take it to be exactly correct. |
| 14552 | Relations are naturally necessary when they are generated by the essential mechanisms of the world [Mumford/Anjum] |
| Full Idea: The relationship between co-existing properties or successive events or states is naturally necessary when they are understood by scientists to be related in fact by generative mechanisms, whose structures constitute the essential nature of things. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 7.3) | |
| A reaction: This is the view I espouse. It doesn't follow that those mechanisms have necessary existence. Given those mechanisms, they can only behave in that way, because behaving in some way is precisely what they are. |
| 14578 | Possibility might be non-contradiction, or recombinations of the actual, or truth in possible worlds [Mumford/Anjum] |
| Full Idea: Possibility could be just logical possibility (as involving no formal contradictions), or recombinations of all the existing elements (Armstrong), or truth in other concrete worlds (Lewis). | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 8.4) | |
| A reaction: All wrong, I would say. Well, avoiding contradiction is obviously a sense of 'possible'. Armstrong is wrong. It rules out new 'elements' being possible, and implies impossible combinations of the current ones. As for Lewis... |
| 14549 | Maybe truths are necessitated by the facts which are their truthmakers [Mumford/Anjum] |
| Full Idea: Some truthmaker theorists are truthmaker necessitarians, believing that the way facts in the world make certain propositions true is by necessitating them. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 3.10) | |
| A reaction: [The cite Armstrong 2007:5-6] I don't believe in this sort of proposition (which turns out, on close inspection, to be just another way of referring to 'the facts'). Propositions are our attempts to express facts, so they can't be necessitated. |
| 14585 | We have more than five senses; balance and proprioception, for example [Mumford/Anjum] |
| Full Idea: The myth of the fivefold division of the sense needs to be overturned. In the experience of causation the senses of balance and proprioception are more important. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 9.1) | |
| A reaction: Thinking is a sensual experience too, especially in its emotional dimension. David Hume always based his empiricism on 'experience', not on the mere five external senses. |
| 14576 | Smoking disposes towards cancer; smokers without cancer do not falsify this claim [Mumford/Anjum] |
| Full Idea: Smoking disposes towards cancer, and has its way in many instances. The existence of some smokers without cancer, however, does nothing to falsify this dispositional claim. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 7.5) | |
| A reaction: Indeed, falsification by one instance will only work against absolute and universal claims, and nature contains hardly any of those. |
| 14551 | If causation were necessary, the past would fix the future, and induction would be simple [Mumford/Anjum] |
| Full Idea: If there were necessity to be found in causation, then the problem of induction would seem to be dissolved. The future would indeed proceed like the past if it were for all time necessitated what caused what. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 3.14) | |
| A reaction: My working hypothesis is that the essences of nature necessitate their interactions, and that the problem of induction is solved in that way. We can allow causation to be a process in this action, the transmitter of necessities. Or it could drop out. |
| 14571 | The only full uniformities in nature occur from the essences of fundamental things [Mumford/Anjum] |
| Full Idea: There is indeed natural uniformity in the negative charge of electrons, but the reason for this is that it is an essential property of being an electron that something be negatively charged. It would not be an electron otherwise. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 6.6) | |
| A reaction: See Idea 14570 for the first part of this thought. This doesn't feel right. The behaviour of gravity according to the inverse square law, or General Relativity, seems to be a uniformity that extends beyond the essences of the ingredients. |
| 14570 | Nature is not completely uniform, and some regular causes sometimes fail to produce their effects [Mumford/Anjum] |
| Full Idea: The uniformity of nature principle, if it means absolute regularity, is simply false; not everyone who smokes gets cancer, not all bread nourishes. Nature is not strictly uniform, even if some things tend to be the case. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 6.6) | |
| A reaction: Something wrong here. The examples are high-level and complex. When someone survives smoking, or bread fails to nourish, we don't infer a disruption of uniform nature, we infer some other uniformity that has intervened. Are there natural kinds? |
| 14569 | It is tempting to think that only entailment provides a full explanation [Mumford/Anjum] |
| Full Idea: It is tempting to think that entailment is the only adequate kind of explanation because of the idea that if A does not entail B, it must have fallen short of (fully) explaining it. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 6.5) | |
| A reaction: Yes. One might dream of saying 'this, and only this, necessitates what happened', but it is doubtful whether causes necessitate effects. It is a quirky view to think that every car accident is necessitated. Nuclear explosions block most events. |
| 14568 | A structure won't give a causal explanation unless we know the powers of the structure [Mumford/Anjum] |
| Full Idea: Knowing the structure that something has does not in itself causally explain that thing's behaviour unless we also know what sorts of behaviour a thing of that structure can cause. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 6.2) | |
| A reaction: I agree with this. If you focus on the lowest possible levels of causal explanation, I can see only powers. Whatever you come up with, it had better be something active. Geometry never started any bonfires. |
| 14556 | Strong emergence seems to imply top-down causation, originating in consciousness [Mumford/Anjum] |
| Full Idea: A problem for strong emergence is that it opens the way for top-down causation if, for instance, our consciousness is causally productive of physical events. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 4.3d) | |
| A reaction: This is what most fans of 'emergent' consciousness would love, presumably because it makes humans really important (nay, godlike!) in the scheme of things. It take it to be based on a hopelessly simplistic view of what is going on around here. |
| 14566 | Causation by absence is not real causation, but part of our explanatory practices [Mumford/Anjum] |
| Full Idea: Causation by absence should be understood in terms of our explanatory practices rather than as a case of genuine causation. There are indeed no powers at work. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 6.1) | |
| A reaction: This seems right, even if from a human point of view some evil person has deliberately desisted from some life-saving action. It is just allowing other causation to happen. A tricky forensic issue, but not an ontological one. |
| 14577 | Causation may not be transitive. Does a fire cause itself to be extinguished by the sprinklers? [Mumford/Anjum] |
| Full Idea: Causation is not always transitive. ...The fire started the sprinkler system and the sprinkler system put the fire out; would we want to say that, by transitivity, the fire caused the fire to be extinguished? | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 7.6) | |
| A reaction: There wouldn't have been an extinguishing of the fire if there had been no fire. But this is a very nice example, against the Millian view that causation consists of every event prior to the effect. The fire is, though, a precondition. |
| 14563 | Causation is the passing around of powers [Mumford/Anjum] |
| Full Idea: Causation is the passing around of powers. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 5.5 3) | |
| A reaction: Hm. This doesn't feel right. Compare 'causation is the passing around of tennis balls'. Can you explain what a power is without mentioning causation? |
| 14587 | We take causation to be primitive, as it is hard to see how it could be further reduced [Mumford/Anjum] |
| Full Idea: We accept primitivism about causation, for how could there be something even more basic in the world than causation, which might allow us to bring forth a reductive analysis? | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], Concl) | |
| A reaction: I think I agree with this view, and for the same reason. I can't imagine how one could cite any 'categorical' or 'structural' properties, or anything else, without invoking causal phenomena in their characterisation. |
| 14533 | Causation doesn't have two distinct relata; it is a single unfolding process [Mumford/Anjum] |
| Full Idea: Rather than depicting causation as between two wholly distinct relata, we argue that it should be seen as a single unfolding process that occurs when a number of mutual manifestation partners meet. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], Pref) | |
| A reaction: I am in sympathy with this view, and like the notion of 'process' in metaphysics, but I worry about what a 'process' consists of. Does it have ingredients? It can last a long time, so presumably it can have parts. Mere time slices? |
| 14558 | A collision is a process, which involves simultaneous happenings, but not instantaneous ones [Mumford/Anjum] |
| Full Idea: When billiard balls collide they deform, and we have a process rather than a momentary collision. Causation is a matter of simultaneity, and simultaneous does not entail instantaneous. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 5.3) | |
| A reaction: This is why they reject the idea that causal relata are abutting events meeting at timeless joints. I think they have got this bit right. It's amazing what a muddle philosophers have got into in just describing what happens in front of their eyes. |
| 14559 | Does causation need a third tying ingredient, or just two that meet, or might there be a single process? [Mumford/Anjum] |
| Full Idea: If causation connects two events, do we need some invisible third element to tie them together? Might there be just two elements so close together that they come as a package deal? Or a single event or process in which one thing turns into another? | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 5.3) | |
| A reaction: [compressed] Hence you find yourself drawn to 'process' philosophy, but preferably without the mystical crust laid over it by A.N. Whitehead. If we could individuate processes, we could dump all sorts of other stuff from our ontology. |
| 14565 | Sugar dissolving is a process taking time, not one event and then another [Mumford/Anjum] |
| Full Idea: It would be counterintuitive to say that we have the cause only when the sugar cube first comes into contact with the water, and the effect only once the whole sugar cube has dissolved. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 5.6) | |
| A reaction: The way we end up thinking about causation is largely dictated by the language we use to describe it. The whole point of philosophy is to scrape away the language and see what is really going on. |
| 14567 | Privileging one cause is just an epistemic or pragmatic matter, not an ontological one [Mumford/Anjum] |
| Full Idea: To speak of 'the' causal explanation privileges some causal powers, but it is implausible that this has a special metaphysical status. Instead, that status should be understood in epistemic or pragmatic terms. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 6.2) | |
| A reaction: I suppose so, but I see a distinction between actions of powers which only explain that one event (striking the match), and actions of powers which explain a whole family of surrounding events (presence of oxygen). |
| 14537 | Coincidence is conjunction without causation; smoking causing cancer is the reverse [Mumford/Anjum] |
| Full Idea: There can be constant conjunction without causation (coincidences) and causation without constant conjunction (smoking causes cancer). | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 1.2) | |
| A reaction: This seems to be presented as a knock-down argument, but I think Humeans can reply to both of them. If you look at the wider pattern of coincidence, or the deeper pattern of coincidence, both of these counterexamples seem to fail. |
| 14573 | Occasionally a cause makes no difference (pre-emption, perhaps) so the counterfactual is false [Mumford/Anjum] |
| Full Idea: Causes can - perhaps they usually do - make a difference but not always. In cases where they don't (such as overdetermination, or late pre-emption), the corresponding counterfactual will be false. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 6.8) | |
| A reaction: The whole idea that we might be able to give a full account of causation in terms of some sort of logical relationship between possible worlds etc. appals me. We need to label something as 'Scientific Logicism', so that we can attack it. |
| 14572 | Is a cause because of counterfactual dependence, or is the dependence because there is a cause? [Mumford/Anjum] |
| Full Idea: There is an obvious Euthyphro question to be asked: is it true that c caused e because e counterfactually depended on c; or did e counterfactually depend on c precisely because c caused e? | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 6.8) | |
| A reaction: The idea that causes could depend on a logical relationship of counterfactual dependence strikes me as so bizarre that only a philosopher could think of it. |
| 14574 | Cases of preventing a prevention may give counterfactual dependence without causation [Mumford/Anjum] |
| Full Idea: We could argue that there can be counterfactual dependence between events without causation, namely, cases of double prevention (an event preventing what would have prevented the second). | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 6.8) | |
| A reaction: Since the whole idea of causation as counterfactual dependence strikes me as utterly counterintuitive, I don't really need these arguments, but it is nice to know that they can be found. Lewis devoted reams of discussion to such problems. |
| 14539 | Nature can be interfered with, so a cause never necessitates its effects [Mumford/Anjum] |
| Full Idea: A natural process can be interfered with, and thus a cause never necessitates its effects. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 1.3) | |
| A reaction: There is the simple point that the world could cease to exist at the instant between cause and effect. But Mumford and Anjum say these two coexist. Finks and antidotes are not conclusive here. Depends what you mean by 'cause' and 'effect'. |
| 14550 | We assert causes without asserting that they necessitate their effects [Mumford/Anjum] |
| Full Idea: We can assert the general claim that smoking causes cancer without endorsing the claim that smoking necessitates cancer. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 3.11) | |
| A reaction: This is the simplest demolition of the idea that effects necessarily follow causes. Necessitarians might wriggle out of it by focusing on the word 'causes' more closely here. Maybe this example isn't a 'strict' usage. |
| 14546 | Necessary causation should survive antecedent strengthening, but no cause can always survive that [Mumford/Anjum] |
| Full Idea: If causation involves any kind of necessity, it should survive the test of antecedent strengthening. ...It is plausible that for any type of causal process, that some new cause can be added which typically results in the effect no longer being caused. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 3.5) | |
| A reaction: [Idea expanded p.57] This is their key argument against the idea that causation involves necessity. In simple terms, show me a cause which necessarily leads to some result, and I will show you how you could prevent that result. Sounds good. |
| 14575 | A 'ceteris paribus' clause implies that a conditional only has dispositional force [Mumford/Anjum] |
| Full Idea: The most persuasive view of a 'ceteris paribus' clause is that the best non-trivially true account that we can give of their meaning is that they indicate that the conditional has dispositional force only. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 6.8) | |
| A reaction: [They cite Lipton 1999] As a general fan of dispositions (as are Mumford and Lill Anjum), this sounds right. If you then add that virtually every event in nature needs a ceteris paribus clause (see N. Cartwright), the whole thing becomes dispositional. |
| 14548 | There may be necessitation in the world, but causation does not supply it [Mumford/Anjum] |
| Full Idea: Causation is consistent with there being necessitation in the world, but we claim that causation does not itself provide that necessitation. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 3.8) | |
| A reaction: Interesting. One might distinguish between causation being necessary, and causation supplying the necessity. The obvious alternative is that essences supply the necessity. |
| 14554 | Laws are nothing more than descriptions of the behaviour of powers [Mumford/Anjum] |
| Full Idea: What we take to be laws are just descriptions of how the powers behave and affect each other. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 4.3c) | |
| A reaction: This is precisely my view, which I first gleaned in its boldest from from Mumford 2004. I idea that ontology does not contain any 'laws of nature' I find wonderfully liberating. Weak emergence is just epistemic. |
| 14564 | If laws are equations, cause and effect must be simultaneous (or the law would be falsified)! [Mumford/Anjum] |
| Full Idea: Physical laws are typically understood as equations, ...but then factors must vary simultaneously, since if one factor varied before the others, there would be a time when the two sides of the equation didn't equate (so Newton's 2nd Law would be false). | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 5.5) | |
| A reaction: Nice. Presumably this thought seems to require action-at-a-distance, which no one could understand. Science oversimplifes the world. See Nancy Cartwright. |
| 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. |
| 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. |
| 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? |
| 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) |
| 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) |
| 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) |
| 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? |
| 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. |
| 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. |
| 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) |
| 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. |
| 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) |
| 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. |
| 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) |
| 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) |
| 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. |
| 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. |
| 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) |
| 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) |
| 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. |