Beyond Weird Quotes

“The world is sensitive to our touch. It has a kind of 'Zing!' that makes it fly off in ways that are not imaginable classically. The whole structure of quantum mechanics may be nothing more than the optimal method of reasoning and processing information in the light of such a fundamental (wonderful) sensitivity. — Chris Fuchs”
― Philip Ball, Beyond Weird

“In quantum theory, words are blunt tools.”
― Philip Ball, Beyond Weird

“The wavefunction tells us where we might potentially find an electron when we look; but what we do find in any given experiment is random, and we can’t meaningfully say why we find it here rather than there.”
― Philip Ball, Beyond Weird

“[Q]uantum physics is not replaced by another sort of physics at large scales. It actually gives rise to classical physics. Our everyday, commonsense reality is, in this view, simply what quantum mechanics looks like when you’re six feet tall.”
― Philip Ball, Beyond Weird

“Quantum theory had the strangest genesis,” Ball says. “Its pioneers made it up as they went along. What else could they do?”
― Philip Ball, Beyond Weird

“When it’s said that quantum mechanics is ‘weird’, or that nobody understands it, the image tends to invite the analogy of a peculiar person whose behaviour and motives defy obvious explanation. But this is too glib. It’s not so much understanding or even intuition that quantum mechanics defies, but our sense of logic itself. Sure, it’s hard to intuit what it means for objects to travel along two paths at once, or to have their properties partly situated some place other than the object itself, and so on. But these are just attempts to express in everyday words a state of affairs that defeats the capabilities of language. Our language is designed to reflect the logic we’re familiar with, but that logic won’t work for quantum mechanics.”
― Philip Ball, Beyond Weird

“[There is a] growing conviction that quantum mechanics is at root a theory not of tiny particles and waves but of information and its causative influence. It’s a theory of how much we can deduce about the world by looking at it, and how that depends on intimate, invisible connections between here and there.”
― Philip Ball, Beyond Weird

“Computer simulation often works fine if we assume nothing more than Newton’s laws at the atomic scale, even though we know that really we should be using quantum, not classical, mechanics at that level. But sometimes approximating the behaviour of atoms as though they were classical billiard-ball particles isn’t sufficient. We really do need to take quantum behaviour into account to accurately model chemical reactions involved in industrial catalysis or drug action, say. We can do that by solving the Schrödinger equation for the particles, but only approximately: we need to make lots of simplifications if the maths is to be tractable. But what if we had a computer that itself works by the laws of quantum mechanics? Then the sort of behaviour you’re trying to simulate is built into the very way the machine operates: it is hardwired into the fabric. This was the point Feynman made in his article. But no such machines existed. At any rate they would, as he pointed out with wry understatement, be ‘machines of a different kind’ from any computer built so far. Feynman didn’t work out the full theory of what such a machine would look like or how it would work – but he insisted that ‘if you want to make a simulation of nature, you’d better make it quantum-mechanical’.”
― Philip Ball, Beyond Weird

“Decoherence is what destroys the possibility of observing macroscopic superpositions – including Schrödinger’s live/dead cat. And this has nothing to do with observation in the normal sense: we don’t need a conscious mind to ‘look’ in order to ‘collapse the wavefunction’. All we need is for the environment to disperse the quantum coherence. This happens with extraordinary efficiency – it’s probably the most efficient process known to science. And it is very clear why size matters here: there is simply more interaction with the environment, and therefore faster decoherence, for larger objects.”
― Philip Ball, Beyond Weird

“Einstein and his colleagues made the perfectly reasonable assumption of locality: that the properties of a particle are localized on that particle, and what happens here can’t affect what happens there without some way of transmitting the effects across the intervening space. It seems so self-evident that it hardly appears to be an assumption at all. But this locality is just what quantum entanglement undermines – which is why ‘spooky action at a distance’ is precisely the wrong way to look at it. We can’t regard particle A and particle B in the EPR experiment as separate entities, even though they are separated in space. As far as quantum mechanics is concerned, entanglement makes them both parts of a single object. Or to put it another way, the spin of particle A is not located solely on A in the way that the redness of a cricket ball is located on the cricket ball. In quantum mechanics, properties can be non-local. Only if we accept Einstein’s assumption of locality do we need to tell the story in terms of a measurement on particle A ‘influencing’ the spin of particle B. Quantum non-locality is the alternative to that view.”
― Philip Ball, Beyond Weird

“[T]he probabilistic nature of the Schrödinger equation, which predicts only the likelihood of different experimental outcomes, leaves it offering no reason why one specific outcome is observed instead of another. In effect, it says that quantum events (the radioactive decay of an atom, say) happen for no reason.”
― Philip Ball, Beyond Weird

“We know that measurements of a quantum system seem to collapse the wavefunction. We most certainly don’t know how, or why, or indeed if that actually happens.”
― Philip Ball, Beyond Weird

“Wavefunction collapse is a generator of knowledge: it is not so much a process that gives us the answers, but is the process by which answers are created. The outcome of that process can’t, in general, be predicted with certainty, but quantum mechanics gives us a method for calculating the probabilities of particular outcomes. That’s all we can ask for.”
― Philip Ball, Beyond Weird

“Everything that seems strange about quantum mechanics comes down to measurement. If we take a look, the quantum system behaves one way. If we don’t, the system does something else. What’s more, different ways of looking can elicit apparently mutually contradictory answers. If we look at a system one way, we see this; but if we look at the same system another way, we see not merely that but not this. The object went through one slit; no, it went through both. How can that be? How can ‘the way nature behaves’ depend on how – or if – we choose to observe it?”
― Philip Ball, Beyond Weird

“The wavefunction of superposed states doesn’t say anything about what the photon is ‘like’. It is a tool for letting you predict what you will measure. And what you will measure for a superposed state like this is that sometimes the measurement device registers a photon with a vertical polarization, and sometimes with a horizontal one. If the superposed state is described by a wavefunction that has an equal weighting of the vertical and horizontal wavefunctions, then 50% of your measurements will give the result ‘vertical’ and 50% will indicate ‘horizontal’. If you accept Bohr’s rigour/complacency (delete to taste), we don’t need to worry what the superposed state ‘is’ before making a measurement, but can just accept that such a state will sometimes give us one result and sometimes another, with a probability defined by the weightings of the superposed wavefunctions in the Schrödinger equation. It all adds up to a consistent picture.”
― Philip Ball, Beyond Weird

“[A]tomic nuclei are pretty hard to peer into. But that’s not the root of the problem. It’s that we simply can’t, for quantum processes, talk about a historical progression of events that led to a given outcome. There’s no story of how it ‘got’ to be that way.”
― Philip Ball, Beyond Weird

“[T]he wavefunction of the electron in [a] box can penetrate into the walls. If the walls aren’t too thick, the wavefunction can actually extend right through them, so that it still has a non-zero value on the outside. What this tells you is that there is a small chance – equal to the amplitude of the wavefunction squared in that part of space – that if you make a measurement of where the electron is, you might find it within the wall, or even outside the wall.”
― Philip Ball, Beyond Weird

“[Q]uantum objects present us with a choice of languages, but it’s too easily forgotten that this is precisely what it is: a struggle to formulate the right words, not a description of the reality behind them. Quantum objects are not sometimes particles and sometimes waves, like a football fan changing her team allegiance according to last week’s results. Quantum objects are what they are, and we have no reason to suppose that ‘what they are’ changes in any meaningful way depending on how we try to look at them. Rather, all we can say is that what we measure sometimes looks like what we would expect to see if we were measuring discrete little ball-like entities, while in other experiments it looks like the behaviour expected of waves of the same kind as those of sound travelling in air, or that wrinkle and swell on the sea surface. So the phrase ‘wave–particle duality’ doesn’t really refer to quantum objects at all, but to the interpretation of experiments – which is to say, to our human-scale view of things.”
― Philip Ball, Beyond Weird

“For many decades quantum theory was regarded primarily as a mathematical description of phenomenal accuracy and reliability, capable of explaining the shapes and behaviours of molecules, the workings of electronic transistors, the colours of nature and the laws of optics, and a whole lot else. It would be routinely described as ‘the theory of the atomic world’: an account of what the world is like at the tiniest scales we can access with microscopes. Talking about the interpretation of quantum mechanics was, on the other hand, a parlour game suitable only for grandees in the twilight of their career, or idle discussion over a beer. Or worse: only a few decades ago, professing a serious interest in the topic could be tantamount to career suicide for a young physicist. Only a handful of scientists and philosophers, idiosyncratically if not plain crankily, insisted on caring about the answer. Many researchers would shrug or roll their eyes when the ‘meaning’ of quantum mechanics came up; some still do. ‘Ah, nobody understands it anyway!”
― Philip Ball, Beyond Weird

“Decoherence – entanglement with the environment – is the very process by which information passes from the quantum system to its environment. It’s what makes this information accessible: what makes the pointer move. Thanks to einselection, the information gets filtered in the process so that only the pointer states survive.”
― Philip Ball, Beyond Weird

“Here, then, is the problem. The fundamental mathematical machinery of quantum mechanics is unitary: the Schrödinger equation which describes how a wavefunction evolves through time prescribes that this evolution is only and always unitary. Yet every experiment ever performed on a quantum system which sets out to directly measure some property of the system induces what we are forced to call ‘collapse of the wavefunction’: it gives a unique answer. And this is necessarily a non-unitary process, and therefore inconsistent with what wavefunctions seem able, in theory, to do. So we have every reason to suppose that quantum mechanics is unitary, and yet we observe non-unitary outcomes of experiments. This is why the measurement problem is so upsetting.”
― Philip Ball, Beyond Weird: Why Everything You Thought You Knew about Quantum Physics Is Different

“A process that conserves information in this way is said to be unitary; shaking the cups, in contrast, is a non-unitary transformation. And the way that quantum systems evolve through time according to the Schrödinger equation is strictly unitary. But quantum measurement seems to violate unitarity: it imposes a violent rupture on the smooth evolution of the quantum wavefunction.”
― Philip Ball, Beyond Weird: Why Everything You Thought You Knew about Quantum Physics Is Different

“Wavefunction collapse is then a generator of knowledge: it is not so much a process that gives us the answers, but is the process by which answers are created.”
― Philip Ball, Beyond Weird: Why Everything You Thought You Knew about Quantum Physics Is Different

“The ‘measurement problem’ is another of the commonly misunderstood notions in quantum physics. It’s often interpreted as meaning that we can’t investigate anything without disturbing it, and that as a result science becomes wholly subjective. Neither clause is accurate.”
― Philip Ball, Beyond Weird: Why Everything You Thought You Knew about Quantum Physics Is Different

“observations not only disturb what has to be measured, they produce it . . . We compel [a quantum particle] to assume a definite position.’ In other words, Jordan said, ‘we ourselves produce the results of measurements’.”
― Philip Ball, Beyond Weird: Why Everything You Thought You Knew about Quantum Physics Is Different

“difference. It’s not easy to see how any physical theory working at the level of known interactions between particles can account for that.”
― Philip Ball, Beyond Weird: Why Everything You Thought You Knew about Quantum Physics Is Different

“Let me add a final word of warning. In a formulation of quantum theory called quantum electrodynamics, developed in the 1950s and 60s by Richard Feynman together with Julian Schwinger and Sin-Itiro Tomonaga, the path that a quantum particle takes as it travels through space takes into account not just straight-line trajectories but every route possible. That’s to say, the equations of quantum electrodynamics contain terms that correspond to every path, however tortuous and crazy. However, when you add all these terms up, most of them cancel out – the wavefunction has essentially zero amplitude throughout most of space. So it’s sometimes said that quantum electrodynamics really does show that an electron or a photon goes through both slits in the double-slit experiment – because it takes every path ‘at once’. However, this picture is just a metaphor for the mathematics. You can think of the particle taking all possible paths if you like, but you can never show that they do. To interpret quantum electrodynamics this way is to attempt to tell a classical story about quantum mechanics. The electron or photon does not take all possible paths. To imagine that it does is not just mistaken; it is fundamentally the wrong way to think about quantum mechanics.”
― Philip Ball, Beyond Weird: Why Everything You Thought You Knew about Quantum Physics Is Different

“There is no quantum world. There is only an abstract quantum physical description. It is wrong to think that the task of physics is to find out how nature is. Physics concerns what we can say about nature.”
― Philip Ball, Beyond Weird: Why Everything You Thought You Knew about Quantum Physics Is Different

“We can’t explain this result in terms of particles, but only in terms of ‘electron waves’. And whereas we might have been content enough to believe that electrons in a bright beam are wave-like and can be diffracted by the double slits, it is hard to understand how one-by-one passage of what seem to be particles (judging from the discrete bright spots that appear on the screen) can produce wave-like interference. We’re forced to conclude that ‘wave-like’ electrons can interfere with themselves.”
― Philip Ball, Beyond Weird: Why Everything You Thought You Knew about Quantum Physics Is Different

“about the outcomes of observations or measurements. This distinction between ontic and epistemic viewpoints is the Big Divide for interpretations of quantum mechanics.”
― Philip Ball, Beyond Weird: Why Everything You Thought You Knew about Quantum Physics Is Different