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).

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.

—

According to Gould and Eldredge, the reason why so many links are missing is that they simply do not exist. They take the view that biological evolution proceeds in successive stages of "punctuated equilibrium." Living species would remain unchanged for extremely long stretches of time, and then undergo profound changes in relatively short periods. To borrow a term from the **quantum** theory of atoms, evolution would occur in "**quantum** jumps." It is very likely that the spark of life appeared during the first such "jump."

— Trinh Xuan Thuan,

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).

Cornelia would not be altogether surprised if she saw the grazing cow start tap dancing, lap dancing, or whatever **quantum** gravity might cause cows to do.

— pg. 249 (Faster than the Speed of Light)

... 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

“Having presented all the relevant nanoscale mechanisms, thus laying down a firm background for the readers’ understanding, the author moves to the topic of architectural challenges in Chapter 7. This field is claimed still to be an unsolved problem so the author gives examples of currently used technologies and points out potential architectural solutions such as self-assembly, carbon nanotubes, or **quantum** systems. That is why it makes the book even more valuable for those who intend to involve nanonetworks in their research.”

— Book Reviews, REVIEWER: JAKUB PALIDER, NANOSCALE COMMUNICATION NETWORKS STEPHEN F. BUSH, ARTECH HOUSE, 2010, ISBN-13: 978-1-60807-003-9, HARDCOVER, 308 PAGES, IEEE Communications Magazine, August 2011

It seems significant that according to **quantum** physics the indestructibility of energy on one hand which expresses its timeless existence and the appearance of energy in space and time on the other hand correspond to two contradictory (complementary) aspects of reality. In fact, both are always present, but in individual cases the one or the other may be more pronounced.

— "Modern Examples of Background Physics" ["Moderne Beispiele zur Hintergrundsphysik"] (1948) as translated by David Roscoe in

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)

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

— Sidney Coleman

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)

I waive the **quantum** o' the sin, The hazard of concealing: But, och! it hardens a' within, And petrifies the feeling!

— Robert Burns,

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** theory was split up into dialects. Different people describe the same experiences in remarkably different languages. This is confusing even to physicists.

— in

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.