The Nature of Empty Space and Nothingness ( Chapter 3 )

According to Science “Nothing is actually one of the most interesting something in all of physics”

So, how do we study Nothing?

Consider an empty Jar. An empty Jar is always contain something, like molecules of air and a bath of infrared light from its warm environment. There’s also the ambient electromagnetic buzz from the surrounding city and a stream of exotic particles from the surrounding cosmos. But what if we suck out every last molecule of air, chill the Jar to absolute zero, and shield it from all eternal radiation? Then the Jar contain only empty space. But it turns out that empty space is far from nothing.

                                                                                                                             (empty space simulation)

Before we begin we should know what is ‘absolute-cold’. Actually it’s impossible to reduce any substance to absolute zero in temperature. Zero Kelvin means no motion whatsoever. But the perfect stillness implies that a particle’s position and momentum are simultaneously perfectly defined and this is impossible according to the Heisenberg uncertainty principle. According to uncertainty principle the position and the velocity of an object cannot both be measured exactly at the same time. Because particles are always uncertain and vibrant in very small scale. So, the walls of the empty Jar will always radiate a heat glow.

But hypothetically what is a perfectly empty space?

The answer will bring us closer to understanding the nature of Space itself. Our universe contain planets, stars and galaxies and those are the things we see. But the only reason these big structures exist is because of the nature of nothingness. We need to understand why we have to go back to the beginning, the very beginning, the Big Bang. We always thought that in the Big Bang the observable universe started from a single point or singularity and then just expended steadily more or less to the point that we are at today. But that's not actually how it happened. There were four different phases in the universe's expansion. To start it was expanding steadily but then after just a tiny fraction of a second the expansion just blew up and the whole universe increased in size by ten to the power twenty six times (10^26) in very short period of time and that period is known as Inflation, which we discussed previously. After that, universe continued expanding but at a decreasing rate. So the expansion of the universe was actually slowing down. But then about five or six billion years ago the expansion of universe started speeding up again and this is caused by Dark energy an energy tied to space. So before that time there was enough matter, the matter density was high enough that it was pulling everything back together and slowing down the expansion. But once the universe reached a critical size then there was enough dark energy to start pushing things apart and that is the phase that we are still in. The expansion of the universe is accelerating.

Although this theory doesn't really explain the formation of particles until we tie in the nature of nothingness. Everything around us is made of particles of atoms and electrons but our best theories of physics are actually field theories.

 Quantum nature of space is described by "Quantum field theory". In short, Space itself is comprised of fundamental quantum fields, one for each elementary particle. Those field oscillate, vibrate with different energies and those oscillation are the electrons, quarks, neutrons, photons, gluons etcetera. That comprise the stuff of our universe. These fields are quantum fields. Now anywhere there's an excitation in this field, that is some energy in the field and that is where we will observe particles.

So the completely empty space is where the values for all of these fields are basically zero. But it's impossible to make a field perfectly flat and zero. We can't take a quantum field and make it completely quiet, because of the Heisenberg's uncertainty principal. It says you can't take a partial and pinpoint it to exactly zero energy. Likewise you can't take a quantum field and make it exactly flat everywhere.

Now, this is very important because ordinarily these fluctuations are really tiny and they only effect subatomic processes. But during that period of Inflation the universe expanded in size so rapidly that those tiny fluctuations got blown up to the scale of the observable universe. Now without them we think the matter distribution in the universe would have been completely homogeneous, completely uniform and that means the gravitational force on any object in the universe would have been the same in all direction. Which means nothing would ever have collapsed into the big structures that we see today. But thanks to these fluctuations there were slightly denser and less dense regions. The denser regions had stronger gravitational fields so they pulled in the matter from around them and that clumped together the matter into huge gas clouds that would go on to be the galaxies that contain the stars and the planets and all other things we known today.

We can actually see the imprint of these quantum fluctuations in the leftover radiation from the Big Bang by the cosmic microwave background radiation.

Now here is another special field which is Higgs field or Higgs boson or God particles. And the mystery become more interesting when we discuss about the origin of Mass itself and bring virtual particle in our discussion.

One of the most amazing things about atoms is they're mainly empty space. So all of the atoms that make up human, trees, air and all the solid things in our universe are mostly empty space. But now we know that empty space is not truly empty.

Empty space is actually full of quarks and gluons field fluctuations. And it is possible to annihilate a quark from empty space, because it's not empty. The empty vacuum actually costs an enormous amount of energy to create. If we create it, we'll discover that is unstable and any sort of perturbation would push that empty vacuum into something where the vacuum is actually full of quantum field fluctuation. Now understanding how the quantum vacuum fluctuations work gives us a sense of what the fundamental particles do.

The origin of Mass is empty space. All of the mass comes from the Higgs mechanism. Which means that all electrons are traveling through Space-time, they interact with the Higgs field and through Higgs field they generate there mass. Higgs field slows them down and stops them from traveling at the speed of light. 

We know most of the mass in our universe comes from neutrons and protons and they are not fundamental particles. They are made of constituent particles called quarks. And the theory that describes quarks and their interaction with each other through gluons is called "Quantum Chromodynamic". According to this theory we can't create an individual quark, because if we try to pull one out then we have to put so much energy into the situation that another quark-antiquark pair will be created.

So, the interesting behaviour about a proton or neutron is that there may be more than three quarks, because additional quark-antiquark pairs can pop in and out of existence. So, at any given time there could be five or seven or any odd number of quarks can make up a proton or neutron. This additional quarks clear out the vacuum. Then the gluon field will suppress in between them. And that is really what is binding these quarks together.

So, where is the mass of the proton coming from? Well obviously the constituent quarks do interact with the Higgs field and that gives them a small amount of Mass. But if we add up the quarks in the proton it would only account for about 1% of it's total mass.

 So, where is the rest of the mass coming from? The answer is energy (E = mc ²). The mass is coming from energy fluctuations in the gluon field and the quarks are interacting with those gluons and that is how the mass is generating. This theory is extraordinary because what we think of as ordinarily empty space actually that turns out to be the thing that gives us most of our mass.

We'll discuss more about virtual particle when we include "Hawking radiation" in our topic.