8 February 2013

The Parallel Universes – Beyond Our Imagination

We hear and see scientists so often talk about Parallel Universes, the mysterious worlds that we cannot see, touch or fill but they might exist. Since Einstein who proposed the Relativity theory, physicist struggle with the concept of existence of these hidden universes. When one of my physics professors for the first time talked about the parallel universe, I was so amazed by the fact. I remember he said some physicist say they exist and this mathematically the proof, so we cannot ignore this theory and say they don’t exist unless we proof they don’t. So what is the exact definition of parallel universe and how the scientist reached the conclusion of their existence? These are the questions that I will try to answer in this article.

A parallel universe also known as Alternative reality is an imaginary independent reality parallel to the one other universe. A number of parallel universes are called a Multiverse and there might be infinite numbers of these universes. In these different universes the physics law may also be different for example in our world we cannot exceed the speed of light but you may exceed it in the some other parallel universe. According to the Quantum physic parallel universes are the universes that divided from each other by a single quantum event.

One other factor we have to consider about the parallel universes is the Infinity. Some cosmologists believe that the space is infinite and we have infinite numbers of spaces which each space contains billion galaxies and stars. So according to the probability law there should be a planet just like earth with the precise same conditions. In other words you have multiple number copies of yourself living in these parallel universes. In some you are doing the exact same thing that you are doing in this current universe and in another you may be a doctor, a chef or even never born. These parallel universes exist alongside our universe in that they may have different history (like word wars never happened) or different laws of nature.

The quantum mechanics deals with the physical phenomena of Particles at microscopic scales. In our daily life what we see in reality is that every object has an exact position, momentum and energy. We observe the chair placed near our desk has a specific shape and dimension. But in quantum physic this is not the case. It was the 1920 when physicists discovered they cannot pinpoint the definite location of atomic particles such as protons or electrons as they don’t have a single location. How is it possible? Can a particle be in different places at the same time?

To explain these phenomena, the existence of Parallel Universes came to reality. Scientists said there must be other universes that particles can be present in them at the same time. But still they couldn’t prove it.

String Theory, Big Bang Theory and Singularity
A matter or object made of atoms in which they contain three components, electrons, neutrons and protons. The electrons are orbiting the nucleus that created by neutrons. The electron made of particles called leptons but neutrons and protons are made of particles called quarks. The string theory was introduced in the 1980. The String Theory states that matters do not compose of particles but instead made of very tiny strings. According to this theory particle like electrons are not only single point but tiny strings that can move and oscillate in different directions. If these strings oscillate in certain directions they called electrons and if they move in other directions they are no longer electrons but protons or quarks. The string theory sometimes called the Theory of Everything as the some physicists believed it can explain all elementary forces of nature and forms of matter. But there was another problem "the Big Bang Theory and the Singularity".

The String theory makes better sense with the Einstein General Relativity and the Big Bang theory except the Singularity. As I said the String theory describes particles as string loops, oscillating at various directions or frequencies. Now what physicists mean by singularity is the exact state before the Big Bang occurred. We know about the giant explosion but what was the universe before the Big Bang? It was a very extremely small point with a very small volume that called Singularity. This small point started expanding and got bigger very fast during the Big Bang. The laws of physics break-down at this point and physicists were not able to explain the singularity either by the General relativity or the String theory.

The M Theory and 11th Dimension
Later after that it was the discovery of the 11th dimension. Particle physicists believed according to the String theory if the strings or particles want to be able to oscillate freely, they need a system with 9 dimensional space plus if we consider Time as an extra dimension then they need 10 dimensional space. The strings are one dimensional (they have only length but not height nor width) mathematical object with a length of 10-35 meters and they oscillate at the speed of light. As humans we can only observe directly 3 dimensions (length, width and height) + time. The M theory or Theory of Everything by introducing of an 11th dimension answered some of the questions. The letter M in the M theory was taken from the word Membrane. As before the M theory scientists agreed on 5 different string theories that at the time they were seemed to be all correct. The M theory unified all of them and now each string theory is a special case of this theory. In short words we can say the strings inside the atoms vibrate in this multiple dimensions and according to their direction or frequency of vibrate they can be seen in 3 dimensional space (the dimensional space that we are able to observe directly) as matter, gravity and light. I have to also mention, the super gravity theory had an important role in discovering of the 11th dimension and the main differences between the 5 superstring theories were the number of dimensions and their attributes.

Now the physicists have the 11th dimension, they can explain the singularity with the existence of the parallel universes. So there must be infinite numbers of parallel universes, floating in the 11th dimension. In the M and String theories, we have a membrane and brane and they depend on the static number of dimensions. 0-brane is a point like particle, 1-brane is a string (one dimensional object), and 2-brane is a membrane and so on. A brane is an entity which can have any number of allowed dimensions. We live in a universe that is a three dimensional brane restricted within a higher or the lager dimensional space. Other branes with different number of dimensions can hold other universes on them. Colliding two branes with each other could possibly cause the Big Bang and creating a whole new world. With the help of the M theory or theory of everything we can say there exists infinite numbers of universes (multiverse) that in each one of them may different law of physics govern. There could be an exact copy of earth or even ourselves exist in these other universes but we can see them as they are in the different dimensions. There could be a precise copy of us (or with a little different) living in the parallel universes at the same time.

4 levels of Parallel Universes
The Parallel Universes categorized into 4 different levels:

Level 1- Regions beyond our cosmic horizon
In the first level of multiverse the same laws of physics govern and the universe considers to have infinite size with infinite number of Hubble volumes. Hubble volume is a spherical portion of the universe surrounding an observer beyond which objects recede from that observer at a rate greater than the speed of light due to the expansion of the Universe. Because it is infinite so there might be another copy of our world lives. The level one parallel universe exists in the same space that our universe exists. 

Level 2- Other post-inflation bubbles 
In this level these parallel universes are contained in giant bubbles. The Inflation theory is the rapid expansion of the universe during the Big Bang when the universe grown so large and rapidly that in our point of view it looks like it is flat. When we observe the cosmos, we find certain points that are so far away from each other but they have the same temperature and characteristics. It is only the Inflation theory that can explain this wide separation. In the second level of parallel universes, these universes live inside the bubble of spacetime and have their own expansion (with consideration of Inflation theory). The laws of nature may be different in these universes.

Level 3- The many worlds of quantum physics
What is the main difference between level one and level two multiverses is that in the first two levels, the duplicated universe are so far away from our universe but in the third level they exists in the same space and time in the different dimensions. What the scientists mean by many worlds of quantum physics is that random quantum processes cause the universe to branch into multiple copies, one for each possible outcome. Each of these possible outcomes or observations corresponds to the different universes. In these multiverses we can find the same fundamental laws of physics but may be with different constants and dimensions (like level 2). In one universe you are alive but in another one you may dead. We can say quantum differences can produce different history in parallel universes.

Level 4- Other mathematical structures
In the last level or level 4 the parallel universes that can be described by different mathematical structures exists. These multiverses can mathematically describe but they cannot observe in our universe. It means their mathematical existence is equal to their physical existence. In the level 4 of the parallel universes we can find different fundamental laws of physics.

Do the Parallel universes really exist? Can we travel through one universe to another universe? Are there infinite copies of our solar system? what is your opinion? Can we live beyond our imagination?