Louis de Broglie quotes:

For X-rays, the phenomenon of diffraction by crystals was a natural consequence of the idea that X-rays are waves analogous to light and differ from it only by having a smaller wavelength.

After long reflection in solitude and meditation, I suddenly had the idea, during the year 1923, that the discovery made by Einstein in 1905 should be generalised by extending it to all material particles and notably to electrons.

The electron can no longer be conceived as a single, small granule of electricity; it must be associated with a wave, and this wave is no myth; its wavelength can be measured and its interferences predicted.

Science itself, no matter whether it is the search for truth or merely the need to gain control over the external world, to alleviate suffering, or to prolong life, is ultimately a matter of feeling, or rather, of desire-the desire to know or the desire to realize.

The actual state of our knowledge is always provisional and... there must be, beyond what is actually known, immense new regions to discover.

In space-time everything which for each of us constitutes the past, the present and the future is given en bloc...Each observer, as his time passes, discovers, so to speak, new slices of space-time which appear to him as successive aspects of the material world, though in reality the ensemble of events constituting space-time exist prior to his knowledge of them.

It seems a little paradoxical to construct a configuration space with the coordinates of points which do not exist.

The history of science shows that the progress of science has constantly been hampered by the tyrannical influence of certain conceptions that finally came to be considered as dogma. For this reason, it is proper to submit periodically to a very searching examination, principles that we have come to assume without any more discussion.

Two seemingly incompatible conceptions can each represent an aspect of the truth... They may serve in turn to represent the facts without ever entering into direct conflict.

We are not sufficiently astonished by the fact that any science may be possible.