Before we can talk about the fusion principle, one will need to understand how the universe is
structured. The best way I can describe the universe is like a bubble in a sea of heat, space in
an ocean of energy. This space was formed as a result of the Big Bang.

The structure is a six sided box shape made from six dimensions.  The six dimensions, also
called branes, are all at right angles to each other and forms a six-sided cube. This six
dimensional cube is a mother universe, and contained in this mother universe is a daughter
universe, formed from the big bang explosion. This daughter universe is what astrophysicist
observes and what we live in.
Branes only react with other at right angles, and at any other angle the branes are invisible
to each other. The only thing that the mother universe and the daughter universe have in
common is gravity.  The astrophysicist perceives this mother universe as dark matter and
dark energy.
These four branes, plus angular
momentum, in a high temperature
plasma, pushes the four hydrogen
nuclei, at the same time, into a helium
nuclei, the excess mass turned into heat
and light.
Today's scientists tell us that the present
day universe contains only about 4% of the
known mass. The other 25% or so, is
considered "dark matter," or matter that
does not interact with light so as to make it
invisible (8). Also, today's scientists are
considering why the universe expansion is
accelerating and have called this
accelerating energy the "dark force" or "dark
energy." In other words, scientists know
that something is out there, they know that
because they can "feel" the gravity.
We observe only four dimensions in our
universe, and it is these four branes, in a high
temperature plasma, that makes
thermal-nuclear reaction possible. One can
actually see the outline of these four branes
in photographs of massive stars, for example
Sirius. (See picture) It shows up as lines in the
shape of a cross. This cross-like shape
outlines the right-angled branes.
Since we know and observe the
four-dimensional space-time, what about the
other six dimensions? One notices that the
angles through Earth are forming a
two-dimensional representation of a corner
of a six-sided cube. The reason the force
went through Earth at this particular angle,
either at 30 degrees or at 45 degrees, is
that Heat, or the force that causes Heat, is a
two-dimensional force. To illustrate this
two-dimensional property of Heat, there is a
simple experiment one can do that
demonstrates this quality.
A candle is placed at each end of a yardstick, enclosed in a glass
to keep the flames from going out. The yardstick is then set in
motion on its own axis. As the yardstick revolves, the flame of the
two candles will bend towards the center of the revolution,
indicating that Heat has the property of traveling towards the
middle of a revolving body.
This idea of two-dimensional branes rotating (angular momentum), causing four hydrogen nuclei to
combine, is not recognized by today’s scientists.
Superstring Theory

String theory introduces a number of
surprising features—such as the
existence of microscopic strings, rather
than particles, as the fundamental units
of matter, along with the existence of
several extra spatial dimensions in the
universe.  The six dimensions, also called
branes, are all at right angles to each
other and forms a six-sided cube. The
branes contain very small strands of
magnetic flux and theorists think these
are nature’s ultimate building blocks.   
These  vibrating strands of energy called
superstrings have always had a big
problem converting skeptics. One
reason: The strings are far too small to
see. The intricate shape determines how
strings can vibrate and, hence, what
kinds of particles exist.
String theory for dummies
String Theory on Wikipedia
Carl Sagan's Cosmos - Tesseract