"measurement"タグの名言

Even if it were possible to cast my horoscope in this one life, and to make an accurate prediction about my future, it would not be possible to 'show' it to me because as soon as I saw it my future would change by definition. This is why Werner Heisenberg's adaptation of the Hays Office—the so-called principle of uncertainty whereby the act of measuring something has the effect of altering the measurement—is of such importance. In my case the difference is often made by publicity. For example, and to boast of one of my few virtues, I used to derive pleasure from giving my time to bright young people who showed promise as writers and who asked for my help. Then some profile of me quoted someone who disclosed that I liked to do this. Then it became something widely said of me, whereupon it became almost impossible for me to go on doing it, because I started to receive far more requests than I could respond to, let alone satisfy. Perception modifies reality: when I abandoned the smoking habit of more than three decades I was given a supposedly helpful pill called Wellbutrin. But as soon as I discovered that this was the brand name for an antidepressant, I tossed the bottle away. There may be successful methods for overcoming the blues but for me they cannot include a capsule that says: 'Fool yourself into happiness, while pretending not to do so.' I should actually want my mind to be strong enough to circumvent such a trick.

It is impossible to escape the impression that people commonly use false standards of measurement — that they seek power, success and wealth for themselves and admire them in others, and that they underestimate what is of true value in life.

What the clock reads is the measure you set

When left alone, quantum particles behave as multiple images of themselves (as waves, really), simultaneously moving through all possible paths in space and time. Now, again, why do we not experience this multitude around ourselves? Is it because we are probing things around us all the time? Why do all experiments that involve, say, the position of a particle make the particle suddenly be somewhere rather than everywhere? No one knows. Before you probe it, a particle is a wave of possibilities. After you've probed it, it is somewhere, and subsequently it is somewhere for ever, rather than everywhere again. Strange, that. Nothing, within the laws of quantum physics, allows for such a collapse to happen. It is an experimental mystery and a theoretical one. Quantum physics stipulates that whenever something is there, it can transform into something else, of course, but it cannot disappear. And since quantum physics allows for multiple possibilities simultaneously, these possibilities should then keep existing, even after a measurement is made. But they don't. Every possibility but one vanishes. We do not see any of the others around us. We live in a classical world, where everything is based on quantum laws but nothing resembles the quantum world.

I used to measure the skies, now I measure the shadows of Earth. Although my mind was sky-bound, the shadow of my body lies here. [Epitaph he composed for himself a few months before he died]

Thought and science are therefore raising problems which their terms of study can never answer, many of which are doubtless problems only for thought. The trisection of an angle is similarly an insoluble problem only for compass and straight-edge construction, and Achilles cannot overtake the tortoise so long as their progress is considered piecemeal, endlessly having the distance between them. However, as it is not Achilles but the method of measurement which fails to catch up with the tortoise, so it is not man but his method of thought which fails to find fulfillment in experience.

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?

[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.

[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.

[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.

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.

I've kind of stopped valuing laughter as the end-all measurement of what I'm doing.

It is also right that we continue to consult with front line workers and the public to ensure that targets are reasonable and achievable, that measurement regimes are proportionate and that the targets take full account of the other reforms that are under way.

During my first year as a graduate student, we worked on a measurement of the isotope shift and hyperfine structure of mercury isotopes.

I have been struck again and again by how important measurement is to improving the human condition.

Numbers are the product of counting. Quantities are the product of measurement. This means that numbers can conceivably be accurate because there is a discontinuity between each integer and the next.

Clock measurement is not time itself. In fact, so opposed are they that one could argue the clock is not a synonym, but the opposite of time.