Curious: Master, what is the universe?
Teacher: The universe consists of all that we can know and sense. Time, as we know it, was started with the birth of the universe.
Curious: How did the universe begin?
Teacher: Before the universe there was nothing. There were no such concepts as space and time. According to the most comprehensive and accurate scientific explanations that we have today, the universe started at a single point with a big bang of immense energy. The universe then started expanding from this primordial hot spot and grew into everything we know today, the galaxies, the stars, our solar system and even ourselves. Today, the universe is very large but is still expanding.
Curious: How old is the universe?
Teacher: It is currently estimated that the big bang happened approximately 13.7 billion years ago.
Curious: What was created by the big bang?
Teacher: In the earliest moments of the big bang there was nothing except an infinitely hot plasma soup of subatomic particles rushing apart in all directions. As the early universe began to cool, at around 10-43 seconds after creation, there existed an almost equal yet asymmetrical amount of matter and antimatter. We know that as matter and antimatter are created together, they collide and destroy one another creating pure energy.
A little later, between 10–12 seconds and 10–6 seconds after the Big Bang, the fundamental forces of gravity, electromagnetism, the strong nuclear force and the weak nuclear force would have taken their present forms, but the temperature of the universe was still too high to allow certain subatomic particles, i.e., quarks, to bind together to form electrons and protons.
Fortunately for us, there was an asymmetry in this expansion of the early universe of about one part per billion that favored matter. As a direct result, the universe was able to mature in a way favorable for matter to persist.
As the young universe continued to expand, this discrepancy between matter and antimatter grew larger. Thus, matter particles came to dominate those of antimatter and as they were created there was no accompaniment of an equal creation or decay of an antiparticle. Thus, the universe developed into what we see now, a predominantly matter universe.
Curious: What, then, is matter?
Teacher: The term matter traditionally refers to the substance that all objects are made of. One common way to identify this "substance" is through its physical properties. A common definition of matter is anything that has weight (mass) and occupies space. However, this definition has to be revised in light of the new science of quantum mechanics, which I will explain later.
Curious: Where do the chemical elements, atoms, electrons and neutrons come in?
Teacher: The chemical elements are the basic building blocks of matter and consist of only one kind of atom. Thus, these elements cannot be decomposed into simpler substances. As of July 2009, the current standard table of elements contained 117 members. Familiar chemical elements include hydrogen, helium, oxygen, iron, gold, etc.
An atom is made up of electrically charged components -- lightweight negative electrons, and positively charged neutrons. The simplest atom is hydrogen, which contains a central positive particle, a proton, and a single electron. The proton is nearly 2000 times heavier than the electron.
Curious: Did the galaxies and stars form during the big bang?
Teacher: No. It is an observed fact that most of the matter in the universe is the three lightest elements: hydrogen, helium, and lithium. These elements were present during the initial formation of the universe, but the heavier elements were formed later from the high pressure and heat in the interior of stars.
As the most massive of these stars reach the end of ther lives, they explode (go supernova) and throw much of their matter back into space. This detritus is rich in the heavier elements and ultimately they conglomerate into other stars, planets, moons, oceans, animals and even peole like ourselves.
Curious: Could there be more than one universe?
Teacher: One could make the argument that if there is no fundamental reason that something cannot exist, then it is not only possible for that thing to exist, but it’s likely that it does. Of course, there might not be a way of detecting other universes, but this does not negate their possible existence. After all, there is no way to detect the means by which a magnet does its magnetic thing, even when we see or can detect the results.
Curious: You mentioned quantum mechanics, what is that?
Teacher: In physics there are two major sub-fields of study, classical mechanics and quantum mechanics. Classical mechanics is used for describing the motion of large (macroscopic) objects, from projectiles to mechanical parts of machinery, as well as very large (astronomical) objects, such as planets, stars, and galaxies. Classical mechanics is one of the oldest and largest subjects in science, engineering and technology.
Quantum mechanics is a set of scientific principles describing the physical reality at the atomic level of matter (molecules and atoms) and the subatomic level (electrons, protons, and even smaller particles). Some of the predictions and implications of quantum mechanics go against our "common sense" of how humans see a set of bodies (a system) behave. This isn't necessarily a failure of Quantum Mechanics - it's more likely to be a reflection of how we as humans are used to describing things at the scale of meters and days rather than much smaller.
Quantum mechanics is the fundamental language that Nature speaks. Nature doesn’t answer questions for certain; it answers questions by giving probabilities. And in quantum mechanics, there’s a possibility that almost anything happens. Including other universes. If cosmologists are queasy about that, they don't have any choice. It comes out of the mathematics.
In quantum mechanics, the Heisenberg uncertainty principle states that certain pairs of physical properties of subatomic particles, like position and speed (momentum), cannot both be known to arbitrary precision. That is, the more precisely one property is known, the less precisely the other can be known. Imagine if this also applied in the macroworld to balls on a pool table. You couldn’t measure the speed of a ball and know where it was on the table at the same time.
Fundamental to contemporary Quantum Theory is the notion that there is no phenomenon until it is observed. This effect is known as the Observer Effect. The implications of the observer effect are profound because, if true, it means that before anything can manifest in the physical universe it must first be observed. Presumably observation cannot occur without the pre-existence of some sort of consciousness to do the observing. The observer effect clearly implies that the physical Universe is the direct result of consciousness.
Quantum mechanics proposes that every possible outcome of every event defines or exists in its own "history" or "world". In layman's terms, there is a very large—perhaps infinite—number of universes, and everything that could possibly have happened in our past, but didn't, has occurred in the past of some other universe or universes. In other words, the results of every decision splits the universe and both copies go off in their own direction. Hence, there is a universe where Hitler and Germany won WWII. Another universe where you have a different sister or brother.
What if you had an identical twin? What if you had 10 identical twins? A million twins? What if all of these "others" were more than just twins in the sibling sense? What if these others were literally “you,” yet living independently in their own world or universe? Astonishing, as it may seem, this may actually be the case. There may be millions, billions, and in fact, an infinite number of "alternate" universes stacked like so much Tupperware within our own universe.
Curious: What is the Theory Of Everything?
Teacher: As physicists and cosmologist have tried to understand the universe they have searched for the fundamental laws of nature that explain why things are as they are. In current mainstream physics, a Theory of Everything would unify all the fundamental interactons of nature, which are usually considered to be four in number: gravity, the strong nuclear force, the weak nuclear force, and the electromagnetic force.
However, the equations that describe gravity are completely different from those for electromagnetism and subatomic interactions. Moreover, each of these theories is incomplete in its own right. For decades, theorists have tried various strategies to roll up the gravitational field and the quantum field into one set of equations. Most of the attempts failed because meaningless infinities showed up in their mathematics.
But one bizarre approach is gaining popularity. It turns out that the equations of quantum theory can mesh perfectly with the theory of relativity — if we look at them from the perspective of a 10-dimensional universe. To resolve this, scientists added six extra dimensions, initially, for a total of ten. These six dimensions were predicted to be contained in tiny curled up formations at every point within our three-dimensional space. This concept is called Superstring Theory, because theoreticians imagine the core components of the universe as tiny loops of string or membranes vibrating in 10 dimensions.
Curious: What is Superstring Theory?
Teacher: Simply put, Superstring Theory says that all particles and forces are manisfestations of different resonances of tiny one-dimensional strings (or possibly membranes) vibrating in ten dimensions. They are so small, our most precise machinery is too crude to detect them.
But if the universe we see and only dimly understand to have four dimensions, really has 10 — where are the other six dimensions? The string theorists contend that when the big bang inflated our four dimensions into the universe, as we know it, the extra six dimensions collapsed into loops smaller than the smallest observed subatomic particle.
But there was still a problem with Superstring Theory. Many string theorists came up with several other theories that all seemed to be correct. Ultimately scientists found that adding an eleventh dimension mathematically explained all of the seemingly different string theories as different aspects of the same theory. This one theory to rule them all is known as M-theory.
The eleventh dimension of string theory predicts a new kind of string, stretched infinitely long to create what is termed a floating bubble-like membrane, or brane. According to string theory, infinite branes exist that each supports a separate but parallel universe.
Finally, string theory offers a possible explanation for the Big Bang. It had long bothered scientists that although they could plot the stages of the Big Bang backwards to the singularity, the initial cause for the event was without explanation. Now string theorists believe that two branes colliding could have caused the Big Bang event.
Curious: Thank you Master. You certainly have given me lots to think about.