If **quantum** communication and **quantum** computation are to flourish, a new information theory will have to be developed.

— Chapter 25, Zeilingers Principle, Information at the root of reality, p. 231

It seems to me that we must make a distinction between what is "objective" and what is "measurable" in discussing the question of physical reality, according to **quantum** mechanics. The state-vector of a system is, indeed, not measurable , in the sense that one cannot ascertain, by experiments performed on the system, precisely (up to proportionality) what the state is; but the state-vector does seem to be (again up to proportionality) a completely objective property of the system, being completely characterized by the results it must give to experiments that one might perform.

— Ch. 6, Quantum Magic and Quantum Mastery, p. 269

O mihi tum longae maneat pars ultima vitae, Spiritus et **quantum** sat erit tua dicere facta.

— To sing thy praise, would heaven my breath prolong,

Infusing spirits worthy such a song.

— Book IV, lines 53–54 (translated by John Dryden).

Murphy's **quantum** Law: Anything that can, could have, or will go wrong, is going wrong, all at once.

—

For the most part, **quantum** theory has been of little practical value in
my life.

— 1997 Skating to Antarctica.

People get a lot of confusion, because they keep trying to think of **quantum** mechanics as classical mechanics

—

The underlying physical laws necessary for the mathematical theory of a large part of physics and the whole of chemistry are thus completely known, and the difficulty is only that the exact application of these laws leads to equations much too complicated to be soluble. It therefore becomes desirable that approximate practical methods of applying **quantum** mechanics should be developed, which can lead to an explanation of the main features of complex atomic systems without too much computation.

—

I liked **quantum** mechanics very much. The subject was hard to understand but easy to apply to a large number of interesting problems.

— W. E. Lamb, Super classical quantum mechanics: the best interpretation of non relativistic quantum mechanics,

A gifted experimentalist, and theoretician, in the best Newtonian tradition... His contributions to **quantum** measurements, and elucidative teachings on **quantum** mechanics, have not yet received the attention they deserve.

— F. J. Duarte (2012).

In mysteries what we know, and our realization of what we do not know, proceed together; the larger the island of knowledge, the longer the shoreline of wonder. It is like the **quantum** world, where the more we understand its formalism, the stranger that world becomes.

— Part of this quote may actually be by [Ralph Washington Sockman].

... one can still say that **quantum** mechanics is the key to understanding magnetism. When one enters the first room with this key there are unexpected rooms beyond, but it is always the master key that unlocks each door.

—

As with all **quantum** devices, a qubit is a delicate flower. If you so much as look at it, you destroy it.

— Chapter 21, The Qubit, Information in the quantum age, p. 187

The theory of **quantum** electrodynamics describes Nature as absurd from the point of view of common sense. And it agrees fully with experiment. So I hope you accept Nature as She is absurd.

— p. 10 (QED: The Strange Theory of Light and Matter (1985))

Et ipse quidem, quamquam medio in spatio integræ ætatis ereptus, **quantum** ad gloriam, longissimum ævum peregit.

— As he, though carried off in the prime of life, had lived long enough for glory.

— Tacitus,

If **quantum** communication and **quantum** computation are to flourish, a new information theory will have to be developed.

— Hans Christian von Baeyer (2003)

The underlying physical laws necessary for the mathematical theory of a large part of physics and the whole of chemistry are thus completely known, and the difficulty is only that the exact application of these laws leads to equations much too complicated to be soluble. It therefore becomes desirable that approximate practical methods of applying **quantum** mechanics should be developed, which can lead to an explanation of the main features of complex atomic systems without too much computation.

— Paul Dirac (1926)

Relativity eliminated the Newtonian illusion of absolute space and time; **quantum** theory eliminated the Newtonian dream of controllable measurement process; chaos eliminates the Laplacian fantasy of deterministic predictability.

— James Gleick (1987), in "Chaos Making a New Science”, p.6, quoted in “Basic Social Policy and Planning: Strategies and Practice Methods”, p.63

However the development proceeds in detail, the path so far traced by the **quantum** theory indicates that an understanding of those still unclarified features of atomic physics can only be acquired by foregoing visualization and objectification to an extent greater than that customary hitherto...

— Werner Heisenberg (1933)

Whenever a time comes that the justice overwhelms and overcomes cruelty, it is prohibited to form negative conjectures and opinions about anyone, except when one knows it about him. But whenever a time comes that cruelty and oppression overwhelms the (**quantum** of) justice, then one must not have good opinions about the beneficence of a person, till such time he knows it(for sure).

— Muhsin al-Am?n,

Anyone who is not shocked by **quantum** theory has not understood it.

— Niels Bohr, as quoted in

**quantum** physics is no longer an abstract theory for specialists. We must now absolutely include it in our education and also in our culture.

—

**quantum** est in rebus inane! How much folly there is in human affairs.

— Persius,

I am a **quantum** Engineer, but on Sundays I Have Principles.

— Opening sentence of his "underground colloquium" in March 1983, as quoted by Nicolas Gisin in an edition by J. S. Bell, Reinhold A. Bertlmann, Anton Zeilinger (2002).

The **quantum** Universe has a quotation from me in every chapter but it's a damn good book anyway.

— Review blurb for the first edition of

After the conversations about Indian philosophy, some of the ideas of **quantum** Physics that had seemed so crazy suddenly made much more sense.

— Werner Heisenberg, "Great Minds on India", Page No. 117.