32 ideas
| 20457 | Zeno assumes collecting an infinity of things makes an infinite thing [Rovelli] |
| Full Idea: One possible answer is that Zeno is wrong because it is not true that by accumulating an infinite number of things one ends up with an infinite thing. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 01) | |
| A reaction: I do love it when deep and complex ideas are expressed with perfect simplicity. As long as the simple version is correct. |
| 17536 | If it can't be expressed mathematically, it can't occur in nature? [Heisenberg] |
| Full Idea: The solution was to turn around the question How can one in the known mathematical scheme express a given experimental situation? and ask Is it true that only such situations can arise in nature as can be expressed in the mathematical formalism? | |
| From: Werner Heisenberg (Physics and Philosophy [1958], 02) | |
| A reaction: This has the authority of the great Heisenberg, and is the ultimate expression of 'mathematical physics', beyond anything Galileo or Newton ever conceived. I suppose Pythagoras would have thought that Heisenberg was obviously right. |
| 20468 | Quantum mechanics deals with processes, rather than with things [Rovelli] |
| Full Idea: Quantum mechanics teaches us not to think about the world in terms of 'things' which are in this or that state, but in terms of 'processes' instead. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 04) |
| 20467 | Quantum mechanics describes the world entirely as events [Rovelli] |
| Full Idea: The world of quantum mechanics is not a world of objects: it is a world of events. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 04) | |
| A reaction: I presume a philosopher is allowed to ask what an 'event' is. Since, as Rovelli tells it, time is eliminated from the picture, events seem to be unanalysable primitives. |
| 17545 | Quantum theory shows that exact science does not need dogmatic realism [Heisenberg] |
| Full Idea: It is only through quantum theory that we have learned that exact science is possible without the basis of dogmatic realism. | |
| From: Werner Heisenberg (Physics and Philosophy [1958], 05) |
| 17538 | Quantum theory does not introduce minds into atomic events [Heisenberg] |
| Full Idea: Certainly quantum theory does not contain genuine subjective features, it does not introduce the mind of the physicist as a part of the atomic event. | |
| From: Werner Heisenberg (Physics and Philosophy [1958], 03) | |
| A reaction: This should be digested by anyone who wants to erect some dodgy anti-realist, idealist, subjective metaphysics on the basis of the Copenhagen interpretation of quantum mechanics. |
| 17534 | A 'probability wave' is a quantitative version of Aristotle's potential, a mid-way type of reality [Heisenberg] |
| Full Idea: The 1924 idea of the 'probability wave' meant a tendency for something. It was a quantitative version of the old concept of 'potentia' in Aristotelian philosophy ...a strange kind of physical reality just in the middle between possibility and reality. | |
| From: Werner Heisenberg (Physics and Philosophy [1958], 02) | |
| A reaction: [compressed] As far as I can see, he is talking about a disposition or power, which is exactly between a mere theoretical possibility and an actuality. See the Mumford/Lill Anjum proposal for a third modal value, between possible and necessary. |
| 17553 | We can retain the idea of 'substance', as indestructible mass or energy [Heisenberg] |
| Full Idea: One could consider mass and energy as two different forms of the same 'substance' and thereby keep the idea of substance as indestructible. | |
| From: Werner Heisenberg (Physics and Philosophy [1958], 07) |
| 17544 | Basic particles have a mathematical form, which is more important than their substance [Heisenberg] |
| Full Idea: The smallest parts of matter are not the fundamental Beings, as in the philosophy of Democritus, but are mathematical forms. Here it is quite evident that the form is more important than the substance of which it is the form. | |
| From: Werner Heisenberg (Physics and Philosophy [1958], 04) | |
| A reaction: Heisenberg is quite consciously endorsing hylomorphism here, with a Pythagorean twist to it. |
| 17550 | We give a mathematical account of a system of natural connections in order to clarify them [Heisenberg] |
| Full Idea: When we represent a group of connections by a closed and coherent set of concepts, axioms, definitions and laws which in turn is represented by a mathematical scheme we have isolated and idealised them with the purpose of clarification. | |
| From: Werner Heisenberg (Physics and Philosophy [1958], 06) | |
| A reaction: Attacks on the regularity theory of laws, and the notion that explanation is by laws, tend to downplay this point - that obtaining clarity and precision is a sort of explanation, even if it fails to go deeper. |
| 5845 | Niceratus learnt the whole of Homer by heart, as a guide to goodness [Xenophon] |
| Full Idea: Niceratus said that his father, because he was concerned to make him a good man, made him learn the whole works of Homer, and he could still repeat by heart the entire 'Iliad' and 'Odyssey'. | |
| From: Xenophon (Symposium [c.391 BCE], 3.5) | |
| A reaction: This clearly shows the status which Homer had in the teaching of morality in the time of Socrates, and it is precisely this acceptance of authority which he was challenging, in his attempts to analyse the true basis of virtue |
| 20469 | There are probably no infinities, and 'infinite' names what we do not yet know [Rovelli] |
| Full Idea: 'Infinite', ultimately, is the name that we give to what we do not yet know. Nature appears to be telling us that there is nothing truly infinite. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 11) |
| 20461 | The basic ideas of fields and particles are merged in quantum mechanics [Rovelli] |
| Full Idea: The notions of fields and particles, separated by Faraday and Maxwell, end up merging in quantum mechanics. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 04) | |
| A reaction: This sounds to me just like Anaximander's 'apeiron' - the unlimited [Rovelli agrees! p.168]. Anaximander predicted the wall which enquiry would hit, but we now have more detail. |
| 17549 | Seven theories in science: mechanics, heat, electricity, quantum, particles, relativity, life [Heisenberg, by PG] |
| Full Idea: Science has seven closed systems of concepts and axioms: Newtonian mechanics; the theory of heat; electricity and magnetism; quantum theory; the theory of elementary particles; general relativity; and the theory of organic life. | |
| From: report of Werner Heisenberg (Physics and Philosophy [1958], 06) by PG - Db (ideas) | |
| A reaction: [my summary of pp.86-88 and 92] It is interesting to have spelled out that there are number of 'closed' theories, which are only loosely connected to one another. New discoveries launch whole new theories, instead of being subsumed. |
| 17540 | Energy is that which moves, and is the substance from which everything is made [Heisenberg] |
| Full Idea: Energy is the substance from which all elementary particles, all atoms and therefore all things are made, and energy is that which moves. | |
| From: Werner Heisenberg (Physics and Philosophy [1958], 04) | |
| A reaction: I'm not sure what energy is, but I like this because it says that nature is fundamentally active. Nothing makes sense without that basic assumption (on which Leibniz continually insists). |
| 17541 | Energy is an unchanging substance, having many forms, and causing all change [Heisenberg] |
| Full Idea: Energy is a substance, since its total amount does not change. ...Energy can be changed into motion, into heat, into light and into tension. Energy may be called the fundamental cause for all change in the world. | |
| From: Werner Heisenberg (Physics and Philosophy [1958], 04) | |
| A reaction: Grandiose stuff. I remain unconvinced that Heisenberg (clever fellow, I'm told) has any idea of what he is talking about. |
| 20462 | Because it is quantised, a field behaves like a set of packets of energy [Rovelli] |
| Full Idea: Since the energy of the electromagnetic field can take on only certain values, the field behaves like a set of packets of energy. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 04) |
| 20463 | There are about fifteen particles fields, plus a few force fields [Rovelli] |
| Full Idea: There are about fifteen fields, whose quanta are elementary particles (electrons, quarks, muons, neutrinos, Higgs, and little else), plus a few fields similar to the electromagnetic one, which describe forces at a nuclear scale, with quanta like photons. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 04) | |
| A reaction: According to Rovelli, this sentence describes the essence of physical reality. |
| 20464 | The world consists of quantum fields, with elementary events happening in spacetime [Rovelli] |
| Full Idea: The world is not made up of fields and particles, but of a single type of entity: the quantum field. There are no longer particles which move in space with the passage of time, but quantum fields whose elementary events happen in spacetime. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 04) | |
| A reaction: If you are not a scientist, there is (I find) a strong tendency to read and digest stuff like this, and then forget it the next day, because it so far from our experience. Folk like me have to develop two parallel views of the nature of reality. |
| 17548 | Maxwell introduced real fields, which transferred forces from point to point [Heisenberg] |
| Full Idea: In the theory of fields of force one came back to the older idea, that action is transferred from one point to a neighbouring point. ...With Maxwell the fields of force seemed to have acquired the same degree of reality as the body's of Newton's theory. | |
| From: Werner Heisenberg (Physics and Philosophy [1958], 06) |
| 20459 | Electrons only exist when they interact, and their being is their combination of quantum leaps [Rovelli] |
| Full Idea: Electrons don't always exist. They exist when they interact. They materialize when they collide with something. The quantum leap from one orbit to another constitutes their way of being real. An electron is a combination of leaps between interactions. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 04) | |
| A reaction: If a philosopher with an Aristotelian interest in the nature of matter wants to grasp the modern view, the electron looks like the thing to focus on. You can feel Rovelli battling here to find formulations that might satisfy a philosopher. |
| 20460 | Electrons are not waves, because their collisions are at a point, and not spread out [Rovelli] |
| Full Idea: Schrödinger's wave is a bad image for an electron, because when a particle collides with something else, it is always at a point: it is never spread out in space like a wave. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 04 note) | |
| A reaction: And yet there is the diffusion in the two-slit experiment, which Thomas Young discovered for light. I must take Rovelli's word for this. |
| 20466 | Quantum Theory describes events and possible interactions - not how things are [Rovelli] |
| Full Idea: Quantum Theory does not describe things as they are: it describes how things occur and interact with each other. It doesn't describe where there is a particle but how it shows itself to others. The world of existence is reduced to possible interactions. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 04) | |
| A reaction: Fans of 'process philosophy' should like this, though he is not denying that there may be facts about how things are - it is just that this is not mentioned in the theory. There is not much point in philosophers yearning to know the reality. |
| 17533 | Radiation interference needs waves, but radiation photoelectric effects needs particles [Heisenberg] |
| Full Idea: How could it be that the same radiation that produces interference patterns, and therefore must consist of waves, also produces the photoelectric effect, and therefore must consist of moving particles. | |
| From: Werner Heisenberg (Physics and Philosophy [1958], 02) |
| 20465 | Nature has three aspects: granularity, indeterminacy, and relations [Rovelli] |
| Full Idea: I think that quantum mechanics has revealed three aspects of the nature of things: granularity, indeterminacy, and the relational structure of the world. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 04) |
| 17537 | Position is complementary to velocity or momentum, so the whole system is indeterminate [Heisenberg] |
| Full Idea: The knowledge of the position of a particle is complementary to the knowledge of its velocity or momentum. If we know one with high accuracy we cannot know the other with high accuracy; still we must know both for determining the behaviour of the system. | |
| From: Werner Heisenberg (Physics and Philosophy [1958], 03) | |
| A reaction: This is the famous Uncertainty Principle, expressed in plain language by the man himself. At this point we lost our grip on the prospects of determining the behaviour of natural systems. |
| 17551 | It was formerly assumed that electromagnetic waves could not be a reality in themselves [Heisenberg] |
| Full Idea: The idea that electromagnetic waves could be a reality in themselves, independent of any bodies, did at that time not occur to the physicists. | |
| From: Werner Heisenberg (Physics and Philosophy [1958], 07) | |
| A reaction: 'At that time' is when they thought the waves must travel through something, called the 'ether'. |
| 17532 | An atom's stability after collisions needs explaining (which Newton's mechanics can't do) [Heisenberg] |
| Full Idea: The first new model of the atom could not explain the most characteristic features of the atom, its enormous stability. No planetary system following the laws of Newton's mechanics would ever go back to its original configuration after a collision. | |
| From: Werner Heisenberg (Physics and Philosophy [1958], 02) |
| 17543 | So-called 'empty' space is the carrier of geometry and kinematics [Heisenberg] |
| Full Idea: From our modern point of view we would say that the empty space between the atoms was not nothing; it was the carrier of geometry and kinematics. | |
| From: Werner Heisenberg (Physics and Philosophy [1958], 04) | |
| A reaction: I'm not sure what the 'carrier of geometry and kinematics' means, but it is interesting that he doesn't mention 'fields' (unless they carry the kinematics?) |
| 20458 | The world is just particles plus fields; space is the gravitational field [Rovelli] |
| Full Idea: The world is made up of particles + fields, and nothing else; there is no need to add space as an extra ingredient. Newton's space is the gravitational field. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 03) | |
| A reaction: I get the impression that particles are just bumps or waves in the fields [yes! Rovelli p.110], which would mean there are fields and nothing else. And no one seems to know what a field is. |
| 20470 | Only heat distinguishes past from future [Rovelli] |
| Full Idea: It is always heat and only heat that distinguishes the past from the future. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 12) | |
| A reaction: I can remember the past but not the future - so can that fact be reduced to facts about heat? |
| 17552 | In relativity the length of the 'present moment' is relative to distance from the observer [Heisenberg] |
| Full Idea: In classical theory we assume past and future are separated by an infinitely short time interval called the present moment. In relativity it is different: future and past are separated by a finite time interval dependent on the distance from the observer. | |
| From: Werner Heisenberg (Physics and Philosophy [1958], 07) | |
| A reaction: Not sure I understand this, but it is a revelation to realise that not only is time made relative to observers, but the length of the 'present moment' also becomes relative. The infinitesimal present moment has always bothered me. |