It is claimed by a lot of spiritual and religious teachings that there exists a mysterious psychic or spiritual energy that pervades the entire universe - for example, the Tao of Taoism, the Absolute in Hinduism, and the Void of Buddhism. We may sit back and ridicule such scientifically unproven concepts but, throughout the ages - from ancient times to the present day - science has invoked similar concepts - albeit by rational thought.
The ancient Greeks proposed a mysterious substance that was thought to fill the universe above the Earth. This was the classical aether and, after air, earth, fire and water, it was the fifth element. Aristotle believed that this fifth element was the main constituent of the heavens. He thought that this element was at its purest in the celestial regions, but becomes adulterated in the region below the moon.
In 1748, Georges Le Sage proposed that the force of gravity is the result of tiny undetectable particles or waves moving at high speed in all directions of the universe - a kind of gravitational aether. This theory was discredited, most notably by James Clerk Maxwell.
In the 19th century, James Clerk Maxwell needed a medium to support his electric and magnetic fields, so he adopted the aether - in this case, the luminiferous aether - in which electric and magnetic fields can vibrate, in the same way as sound waves propagate through the air. In fact, just as the vibration of air is sound, it was thought that the vibration of the aether was electromagnetic waves. This aether was indeed mysterious: it was totally transparent and undetectable, yet it was everywhere - even in a vacuum.
The Michelson-Morley experiment in 1887 showed that the aether had no effect on light waves, and Albert Einstein dealt the final blow to the concept of a luminiferous aether when his special theory of relativity of 1905 showed that the aether was not necessary.
But this was not the end of aether-type concepts. In 1952, in an effort to explain the particle-wave duality in the quantum world, David Bohm came up with the Guided Wave Theory (GWT). According to Bohm, particles are never waves. However, associated with every particle is an undetectable quantum potential which guides the particle's motion - a guiding wave or pilot wave in an unobservable quantum field. This quantum field permeates all of spacetime but it doesn't diminish with distance and exerts no force. It is a quantum potential that binds the entire universe together into what Bohm called a seamless unbroken wholeness. How does it explain the wave-particle duality? Well, in the case of the famous double-slit experiment, each particle goes through only one slit, but its pilot wave goes through both. And, get this, the pilot wave is able to guide the particles without ever exerting any force on them. Understandably, many physicists do not find GWT very convincing - particularly since it invokes a mysterious field that permeates the entire universe - but mainstream physics tells us that a vacuum is not really empty; it is filled with many virtual particles (quantum foam). And what about the mysterious Higgs field? The Higgs field is a quantum field that allegedly permeates the entire universe and mediated by the hypothetical Higgs boson as a messenger. According to the theory, all particles get their masses from interacting with the Higgs field. Hopefully, when the Large Hadron Collider is up and running in 2008, we will be able to have evidence confirming or denying the existence of this mysterious field.
Even cosmology has its own mysterious, undetectable energy. In 1964, the cosmic microwave background radiation was discovered - a radiation that is thought to be observable everywhere in the universe. This radiation is almost exactly (to 99.999% accuracy) the same temperature of 2.725K everywhere in the sky. According to the Big Bang model of the 1970s, points in the universe that have never been in contact have the same temperatures. This homogeneity is remarkable when it is considered that Einstein's special relativity disallows information transfer faster than the speed of light. How can photons across distant regions of the universe (that have never been in contact) have practically the same temperature? A solution to the problem was proposed in 1981 by Alan Guth, with the Inflationary model. Problem solved (or at least explained). But suddenly a new problem emerged. Inflation predicted a flat universe (referring to its curvature), but astronomical observations revealed that the amount of matter in the universe (baryonic and dark) accounted for only 30-40% of the critical density required for a flat universe. It was also observed that the universe expansion is currently accelerating. The only way to reconcile the inflationary model with the energy density measurements is to introduce a kind of repulsive gravity. Adding this repulsive gravity - or dark energy - gives us the critical density required for a flat universe. This dark energy is a very mysterious field and we have no idea what it could be (some might justifiably say that it is a fudge factor and that there is something wrong with the Big Bang model). The universe seems to be permeated by a matter field with a non-zero potential energy, whose only role seems to be to drive its accelerated expansion.
I wonder if all these undetectable energies and fields - Higgs, GWT, quantum foam, and dark energy - are all one and the same phenomenon. Or do we need to wait for a super genius of the likes of Einstein to explain them away and come up with new and revolutionary ideas?
Thoughts about science, human nature and other stuff.
