Physics, in particular, condensed matter physics, is a very old field. Many people are thinking that the exciting time of physics has passed. We enter the begining of the end of physics. The only important things in physics are its engineering applications, such as optical fiber and blue LED.

However, I feel that we only see the end of the begining. The exciting time is still ahead of us. In particular, now is a very exciting time in physics, like 1900 - 1930.

Historically, physics has experienced four revolutions: mechanical revolution, electromagnetic revolution, general relativity revolution, and quantum revolution. Each revolution unifies seemingly unrelated phenomena. Each revolution requires new mathematics to describe the new theory. Each revolution changes our world view. Now we are seeing/making the **second quantum revolution** which unifies (quantum) information, matter and geometry:

Wheeler's "it from bit" represents a deep desire to unify matter and information. In fact, it happend before at a small scale. We introduced electric field to informationally (or pictorially) describe Coulomb law. But later, electric field became real matter with energy and momentum, and even a particle associated with it.

However, in our world, "it" are very complicated. (1) Most "it" are fermions, while "bit" are bosonic. Can fermionic "it" come from bosonic "bit"? (2) Most "it" also carry spin-1/2. Can spin-1/2 arises from "bit"? (3) All "it" interact via a spectial kind of interaction -- gauge interaction. Can "bit" produce gauge interaction? Can "bit" produce waves that satisfy Maxwell equation? Can "bit" produce photon?

More generally, there are** Eight wonders **in our universe (ie "it" has eight wonders)::

(1) Locality.

(2) Identical particles.

(3) Gauge interactions.

(4) Fermi statistics and spin-1/2.

(5) Chiral fermions.

(6) Small mass of fermions. (Much less than Planck mass)

(7) Lorentz invariance.

(8) Gravity.

It turns out that we can only produce two out of eight wonders (1 -- 2) from bits.

However, if we start with qubits, we can obtain Fermi statistics, spin-1/2, Maxwell equation, Yang-Mills equation, and the corresponding gauge interations. So far, we can unify seven out of eight wonders (1 -- 7) by qubits, and we are trying to add the gravity (see http://arxiv.org/abs/0907.1203 ).

So **It from qubit, not bit**. Bit is too classical to produce Gauge interactions, Fermi statistics, and Chiral fermions.Those phenomena (or properties) come from quantum many-body entanglement, which exists only for qubits. (For more deails see http://blog.sciencenet.cn/blog-1116346-736093.html )