**For hundreds of years scientist have tried to unify the laws of physics. Recently, researches came up with appealing ideas about the universe. With use of Einstein’s Theories and the European laboratory for particle physics in Geneva, the belief of something called the String Theory arises among physicists.**

### Visualizing the dimensions

When looking at a point, it has no size nor a dimension. A point is an imaginary idea indicating a position in a system, just like a coordinate. Adjusting a second point, and joining these two points together by means of a line gives us the first dimension. The first dimension has a length. Consequently, the second and third dimension are created by adding width and depth. People understand the first three dimensions effortless, simply because we live in them. Before the age of one, our brains have already adapted the principle of a three dimensional space. According to String Theory, the universe consists of more than three dimensions. What are these other dimensions and how are these dimensions visualized?

The fourth dimension is time according to physics. Time will show the location of a third dimensional object at a certain moment in three dimensional space. If people would live in the fourth dimension they could move along their own timeline and travel through time. In order to find the fifth dimension, time should not be seen as something linear. Instead, it is another movable object. Imagine being this object time and moving forward or backward. By going left and right as well, you enter the fifth dimension. Logically moving up or down brings you in the sixth dimension. All the permutations of choices made are found in these new dimensions. The fifth and sixth dimension are all possibilities of being at a certain place in time. Still, there are five more dimensions.

If you now take a point, you can move it through space and through time, including all the futures and pasts for this certain point. What would happen if this point is moving along a number line where the laws of gravity are different, the speed of light has changed and so on? Dimensions seven till ten are different universes with different possibilities and impossibilities and even different laws of physics. These final dimensions grasp all the possibilities and permutations of how each universe operates and the whole of reality with all the permutations therein throughout all of time and space. Again, the three dimensional idea of length, width and depth is applied, only now for the seventh, eighth and ninth dimension, respectively. The tenth dimension is the encompassment of all of those universes, possibilities, choices, time and places, all into a single thing: everything ever.

### The multiverse of universes

Another theory says there are eleven dimensions instead of ten. Imagine the universes as the skin of bubbles floating through space. One of the characteristics of such a bubble is that together with another bubble there can occur a collision of two universes or a fissioning of two universes. This last feature is known as the Big Bang Theory. In String Theory, as explained above, the bubbles come in different dimensions. The highest dimension is the eleventh, since going beyond this level would make the universe unstable and it would collapse back to the eleventh dimension. The eleventh dimension is known as the multiverse of universes. One question that comes to mind at this point is the following. If there are other universes: can we go between universes? Although this question will not be answered for a long time. Theoretically we can state that maybe one day we might create a wormhole between the universes. Think of this by taking a unit of paper and putting two dots on it. Obviously the shortest distance between the two is a line. By folding the paper you can create a shortcut between the two points, through space and time.

Up until today, no experimental evidence is available to confirm the existence of these extra dimensions. This is one reason why some physicists reject this theory. Nevertheless, scientists cannot see these other dimensions yet, since the extra dimensions might be curled up at such tiny scales, it is impossible to observe them. Moreover, on the other hand the idea of String Theory is still compelling since it includes everything. How is it possible one theory includes the entire universe?

### The standard model

Einstein breaks down at the instant of the Big Bang and the centre of a black hole. Yet, this is not enough and physicists ask for a higher theory. String theory takes you before the Big Bang. After more than fifty years of firing protons at other protons in the Large Hadron Collider at CERN in Geneva the standard model has been created. The standard model consists of hundreds of subatomic particles arranged by their characteristics. Unfortunately, this is still a hideous theory since there is no clear image of all the subatomic particles. Therefore, scientist went looking for a more unifying theory. Moreover, the standard model only describes four percent of the matter of the universe and is therefore not comprehensive. The String Theory includes the part that we are missing at this point.

The standard model including among others bosons, photons, gluons and electrons is nothing but the lowest octave of a vibrating string. Dark matter makes up 27% of the universe and belongs to the next vibration, which is the next octave of the string. Furthermore, roughly 68% of the universe consists of dark energy and takes place when you break the symmetries of the string. The theory tries to answer the following question: what are the basic fundamental, undividable, unchangeable, constituents that create earth around us? Physicists want to unify the laws of physics. The String Theory is therefore also known as the Theory of Everything. At first sight the String Theory has nothing to do with the idea of extra dimensions.

### The String Theory

We know we have atoms and they consist in turn of protons, neutrons and electrons. The neutrons and protons have even smaller particles inside of them known as quarks. At this point, conventional ideas stop. Nevertheless, String Theory goes on. Deep inside the quarks there are vibrating strings and since these strings can vibrate in different patterns they produce different particles. We have radiation particles, matter particles, photons and so on, all built from the same entity. According to the theory, the strings are of the Planck length. Every string has a unique resonance. For instance, the graviton is predicted by the theory to be a string with wave amplitude zero. Superstring theory is based on supersymmetry. No supersymmetric particles have been discovered yet which makes the theory still questionable.

When you study the mathematics of String Theory, you find out that it doesn’t work in an universe that just has three dimensions of space. It only works in an universe that has ten dimensions of space and one dimension of time. String Theory is therefore an attempt to explain all of the particles and fundamental forces of nature by modelling them as vibrations of tiny supersymmetric strings.

People still try to figure out how gravity affects time and how the higher dimensions effect quantum theory. The compelling idea of one unifying theory is still there to be verified and evidence seems still far away.

*Dit artikel is geschreven door Anne Dumoulin*