DARK of the UNIVERSE

Space is a vacuum, we all know that. In the vacuum of outer space, there is no atmosphere like on Earth, there is no air. The lack of air means that, there can be no sound waves. There is no gravity (in the vacuum, the totally empty space) so things don't behave like they would on Earth. Everything floats freely, most of us have seen astronauts floating freely in the low gravity of space. The vacuum of space is not entirely empty, infact there is a lot of stuff in the, so called, vacuum. Believe it or not... But I need to say to you reading this, that these are mostly theories still. Even when everything is said and done, we do not know surely what this "dark energy" is in the cosmos. There are hundreds of theories and candidates for it. Here is the general idea, that I think is pretty logical and interesting.

WMAP image. Cosmic Microwave Background

The Big Bang was the begining of everything in the universe, even the universe itself. About 13.75 billion years ago everything was created, from an indesimal point (you could say "singularity") and because of the extreme heat atoms and particles were moving super fast. Then came the "Big Bang" and all was created and started to expand exponentialy so that in a fraction of a second the whole universe expanded to the size it (nearly) is today. It seems that the universe is still expanding. Because of the vacuum energy expanded and got colder the expansion of the universe slowed down and cooled down. No one knows when it will stop, if ever. What is certain is why the universe is expanding, thanks to quantum theory (that everything has also wave-like properenties in addition to their particle-like behavior) and the Heisenberg uncertainty principle. Alltough we know what happened after the big bang, we can not know what caused it to happen. What was the catalyst?

Quantum theory says that there are these "virtual particles" everywhere, even in the vacuum and in the empty space and voids. These particles are called "virtual" because they excist only for short period of time. These particles can be any particle, like proton, neutron, electron or photon. What makes it "virtual" is the fact that, when this particle pops into existence, anti-particle is also created and therefore annihilate eachother. The energy of vacuum stays at zero, bacause of this annihilation of virtual particles. Positive and negative vacuum energy is 0. But, what if,  it is not and the positive slightly outnumber the negative. These "virtual particles" affect even the structures of the atom. If we look at the hydrogen atom for example the theoretical calculated energy levels are wrong if you do the calculations without the quantum effect (ignoring the virtual particles in the empty space of the hydrogen atom or any atom for that matter). Theory agrees with reality when you include the quantum effect.

So how can we know that the universe is expanding? Well, the space between the galaxies is increasing as well as the space between the superstructures of cosmos. This has been measured by scientists. There is this theory, called the Inflation, It is not entirely new theory, but sort of a tweak to the classical Big Bang theory. There has been made some tweaks to the early parts, the hypothesis of the vacuum energy and when universe was still really young. Most notable change is that, the universe expanded faster than light. Wait, doesn't Einsteins theory of relativity, prohibit faster-than-light speeds? Yes it does, but, then again this is Quantum mechanics and the theory of relativity says that, nothing can travel faster than light, across the universe and the very fabric of space-time. This then is violation of the classical theory? Yes, it is violation of the classical laws, but it is not a direct violation of the quantum laws because the universe it self was moving faster than light. Nothing can move faster than light IN the universe.

There is this test, called the Casimir test. Two plates, with nearly no mass at all, no electric charge and placed in a complete vacuum in outerspace, close to each other. What happens? The plates start to move towards each other. Because the virtual particles and waves are more infinite than inside the two plates. The wave-lenghts can be anything and everything outside the plates. Inside, wavelenght must be so that it fits between the plates. So, the energy of the vacuum is, infact, more than between the plates. How infinity can be more or less, compared to another infinity? Because quantum theory, that is.  What this means is that, when you got multiple objects in space they tend to attract each other when they get close enough, both gravitationaly (if there is enough mass) and at the quantum level. This is how everything accumulate in space. From the tiny atoms to planets and galaxies. This is what makes them to stick together and what makes them grow. 

Picture from Wikipedia

I hope, this made any sense at all, tried to keep it short and compressed. There is just so much stuff to write about. Maybe, somebody even got something out of this jiberjaber...