Identity of Matter, Energy and Force
The horizontal line of beads illustrates a beam of protons and a beam of anti-protons, which are accelerated in opposite directions. When the beams have gained sufficiently high energy, a proton and an anti-proton are brought to collide. Owed to annihilations at the quark-level, the proton and antiproton vanish in a burst of energy which takes the shape of a top-quark and its anti-quark. Both top-quarks instantly decay into a bottom-quark, its anti-quark and two W-bosons. The two bottom-quarks move a short distance before they decay into two energetic jets. One of the W-bosons, the W+ at the upper right, decays into an up-quark and a down-anti-quark, which both decay into jets. The W- at the lower left decays into a muon and an anti-neutrino, which both survive. In the image the sizes of the quanta are proportional to their (rest)masses. Thus, the image evidently depicts a set of fundamental processes where kinetic energy is turned into matter and partly back to energy again.
Processes like the one depicted can be considered as rapid matter-energy oscillations. The reader may be familiar with Einstein's famous equation from early this century: E=mc^2 (energy equal to mass times the speed of light squared) which expresses the equivalence between matter and energy. Technically, this equation still holds true but conceptually it is somewhat outdated. At the fundamental levels, encountered nowadays, any discrimination between matter and energy is obsolete - so it is more reasonable to speak about identity rather than equivalence. As a matter of fact, Quantum Field Theorists usually set the speed of light c=1 throughout formulas - so that Einstein's equation now reads E=m. As one natural consequence, mass and energy are measured in the same units. Actually, the mass of a quantum is not a measure of the amount of matter carried by the quantum, it is a measure of the amount of energy confined in the quantum. At the quantum level there are no traces of the phenomenon called matter.
Field quanta are not discrete little entities that can be picked out and observed in isolation - so how do physicists know about their existence? - Well, there are a handful of methods of detection. One of the ways a specific quantum reveals its existence is as a resonance - i.e. a peak in an otherwise monotonic curve of one or other quantity measured as a function of energy. The figure to the left thus reveals the existence of a quantum (a Z-boson) having the mass of 91 GeV (Giga electronic Volt). Actually, as far as the quality mass is concerned, there is no true difference between quanta. A quantum is just a specific state of vibrating energy and different masses are just different levels of energy.
While the identity of matter and energy is evident at the quantum level, the identity may not seem quite so obvious at the macroscopic level of e.g. a piece of furniture. However, furnitures are just compound bodies composed of the entities encountered at the quantum level. Thus, the seemingly solid matter around us truly is just confined energy - or rather, certain compound states of vibrating energy-fields.
Now, how about the phenomenon called force? - Consider the processes illustrated by the image at the top of this page. Here the W-bosons signify that the weak force is responsible for the decay of the top-quarks. Let us make a Feynman-diagram - an important requisite when physicists analyze quantum processes:
The lines in the Feynman diagram are just symbolic and must not be mistaken for actual quantum trajectories. The X to the left represents an (to us) unknown force-carrier exchanged between the top-quarks and the quarks of the collided proton-anti-proton pair - or in plain words, the X represents the energy-burst from the collision. The central part of the diagram illustrates that the weak force is mediated by an actual exchange of W-bosons - and nothing else. Now, since quanta are just certain energy-states, force evidently is just another name for energy-exchange.
This principle, that force is exerted by means of exchanges of quanta, applies quite generally to any interaction on the quantum level. Similar diagrams can be drawn with the W-bosons (charged weak force) replaced by photons (electromagnetic force), gluons (strong force) or Z-bosons (neutral weak force).
So, summing up, what have we got now? - Matter is just energy confined in quanta. Force is just an exchange of energetic quanta. Quanta are just discrete manifestations of fields. Thus, what we have got is that the various phenomena and appearances are just variations in underlying energy-fields. However, since there actually are different quanta which behave differently, we have a whole set of fields. Nevertheless, as we shall see next, all these fields have a common origin.
