Flux is a science fiction novel by Stephen Baxter. The story of a post-human species, engineered to live in the mantle of a neutron star.

The main protaganist, Dura is ten microns tall, made of nucleonic matter, sees sound, smells photons and swims against magnetic fields. But her incredible world is torn apart as she learns of the true role of her engineered race in Humanity's millennia-long war against the godlike Xeelee.

Although this book stands on its own, it is really part of Baxter's Xeelee Sequence, the neutron star seems to be a weapon and built by humans. It's not explicitly stated, but probably the weapon is to disrupt the Xeelee's greatest engineering work a vast Ring woven from cosmis strings.

Flux (from Latin "to flow") is a substance that facilitates the flow of solder by preventing the formation of oxides. Flux prevents oxides from forming by being more reactive with oxygen than the metals and solder that the flux is applied to. Generally flux is combined with water to make a fluid that can be painted or sprayed onto the workpiece. When heat is applied the water evaporates to leave a glassy coating. As oxygen and other elements combine with the flux it becomes less effective.

--Partially excerpted from The Complete Metalsmith by Tim McCreight.
flux is a concept used often in the field of vector calculus. It can be described in simple terms as the "amount" of a vector field that passes through a certain surface area. In mathematical terms, the flux F is defined as the integral of the dot product of the vector field F and the surface normal N over the surface, like so:

F = ∫s N · F ds

Flux is used a lot in engineering to describing the flows of various things such as fluids (liquids and gases), and the magnetic field inside of transformers.

The flux is intimately tied to the concept of divergence, the infinitesimal limit of the ratio of flux through a closed surface to the volume enclosed by that surface.

Flux (?), n. [L. fluxus, fr. fluere, fluxum,to flow: cf.F. flux. See Fluent, and cf. 1st & 2d Floss, Flush, n., 6.]

1.

The act of flowing; a continuous moving on or passing by, as of a flowing stream; constant succession; change.

By the perpetual flux of the liquids, a great part of them is thrown out of the body. Arbuthnot.

Her image has escaped the flux of things, And that same infant beauty that she wore Is fixed upon her now forevermore. Trench.

Languages, like our bodies, are in a continual flux. Felton.

2.

The setting in of the tide toward the shore, -- the ()bb being called the reflux.

3.

The state of beinng liquid through heat; fusion.

4. Chem.& Metal.

Any substance or mixture used to promote the fusion of metals or minerals, as alkalies, borax, lime, fluorite.

White flux is the residuum of the combustion of a mixture of equal parts of niter and tartar. It consists chiefly of the carbonate of potassium, and is white.- Black flux is the ressiduum of the combustion of one part of niter and two of tartar, and consists essentially of a mixture of potassium carbonate and charcoal.

5. Med. (a)

A fluid discharge from the bowels or other part; especially, an excessive and morbid discharge; as, the bloody flux or dysentery. See Bloody flux.

(b)

The matter thus discharged.

6. Physics

The quantity of a fluid that crosses a unit area of a given surface in a unit of time.

Flux, a. [L. fluxus, p. p. of fluere. See Flux, n.]

Flowing; unstable; inconstant; variable.

The flux nature of all things here. Barrow.

Flux, v. t. [imp. & p. p. Fluxed (?); p. pr. & vb. n. Fluxing.]

1.

To affect, or bring to a certain state, by flux.

He might fashionably and genteelly . . . have been dueled or fluxed into another world. South.

2.

To cause to become fluid; to fuse.

Kirwan.

3. Med.

To cause a discharge from; to purge.