Werner Heisenberg Quotes

Quantum mechanics brought an unexpected fuzziness into physics because of quantum uncertainty, the Heisenberg uncertainty principle.

In relativity, movement is continuous, causally determinate and well defined, while in quantum mechanics it is discontinuous, not causally determinate and not well defined.

The uncertainty relation does not refer to the past; if the velocity of the electron is at first known and the position then exactly measured, the position for times previous to the measurement may be calculated.

Thus, the more precisely the position is determined, the less precisely the momentum is known, and conversely.

If we look at the way the universe behaves, quantum mechanics gives us fundamental, unavoidable indeterminacy, so that alternative histories of the universe can be assigned probability.

The world is not made up of particles and waves and beams of light with a definite existence. Instead, the world works in a much more exploratory way. It is aware of all the possibilities at once and trying them out all the time. That is a hard thing to picture.

Now, what that means is that there is fundamental indeterminacy from quantum mechanics, but besides that there are other sources of effective indeterminacy.

In science fiction, basic doubts featured prominently in the worlds of Philip K. Dick. I knew Phil for 25 years, and he was always getting onto me, a scientist. He was a great fan of quantum uncertainty, epistemology in science, the lot.

If we have an atom that is in an excited state and so is going to emit a photon, we cannot say when it will emit the photon. It has a certain amplitude to emit the photon at any time, and we can predict only a probability for emission; we cannot predict the future exactly.

For as long as one has no further point of reference, apart from the position of the maximum, the wavelength thus remains uncertain by an integral factor.

It's not clear in physics why you can't see the future.

Quantum mechanics brought an unexpected fuzziness into physics because of quantum uncertainty, the Heisenberg uncertainty principle. String theory does so again because a point particle is replaced by a string, which is more spread out.

Spreading out the particle into a string is a step in the direction of making everything we're familiar with fuzzy. You enter a completely new world where things aren't at all what you're used to.

Modern physics often advances only by sacrificing some of our traditional philosophical convictions

All kinds of physical considerations become senseless when we try to apply them to distances smaller than 10 -13 centimeter.

Among the lesser effects of quantum theory are gaping holes in old ideas about causality.

It is true that in quantum theory we cannot rely on strict causality. But by repeating the experiments many times, we can finally derive from the observations statistical distributions, and by repeating such series of experiments, we can arrive at objective statements concerning these distributions.

The uncertainty principle refers to the degree of indeterminateness in the possible present knowledge of the simultaneous values of various quantities with which the quantum theory deals; it does not restrict, for example, the exactness of a position measurement alone or a velocity measurement alone.

Science rejects the indeterminate.

Somewhere around the place I've got an unfinished short story about Schrodinger's Dog; it was mostly moaning about all the attention the cat was getting.

The more one chases the quanta, the better they hide themselves.

When you cut into the present the future leaks out.

When we try to observe things that are very small, the act of observation itself will significantly disturb the state we are seeking to measure.

If we ask, for instance, whether the position of the electron remains the same, we must say 'no'; if we ask whether the electron's position changes with time, we must say 'no'; if we ask whether the electron is at rest, we must say 'no'; if we ask whether it is in motion, we must say 'no'.

If you have nothing in quantum mechanics, you will always have something.