The simplest way to picture the influence of "empty space" is to think about the two best known forces. The inverse square law applies to both electromagnetism and gravitation: attraction decreases exponentially with distance. Hence there is a relationship between a force and space. These two forces act at a distance, but somehow their "strenth" depends on the distance, as if the "nothing" in between two bodies contributed to the measured strength at each side. In technical terms, this is expressed as a "field". And that's what the book is about: what is "inside" that field? The book makes a lengthy preamble to get there.

Newton's law of motion apply to inertial frames and those laws are the same for all inertial frames. However, Maxwell noticed that an electric phenomenon in one inertial frame was a magnetic phenomenon in another. An electric phenomenon in movement gives rise to a magnetic phenomenon, and viceversa, but the "movement" depends on who is observing: if you observe the electric phenomenon while it is moving in front of you, you perceive a magnetic phenomenon; if you "ride" on the electric phenomenon (which is therefore at rest from your viewpoint), you instead only perceive an electric phenomenon. Maxwell's equations showed that the electromagnetic phenomenon "oscillates" like a wave and all such waves travel at 300 thousand kms/hour. Light is one particular electromagnetic wave, hence that speed is known as "the speed of light". What we perceive as different colors of light correspond to different frequencies, not velocities. And some frequencies of electromagnetic waves we can't perceive at all. The interaction between distant bodies does not happen immediately but is mediated by a "field".

Close then summarizes relativity and how it blended Newton and Maxwell into a consistent theory of matter, unfortunately at the expense of absolute spacetime. The intellectual bulk of the book comes with Quantum Mechanics. The vacuum cannot be empty because of the uncertainty principle: there is a minimum energy even in the vacuum, the zero-point energy. Paul Dirac interpreted the vacuum as an infinite set of particles with all sorts of energies. Under special circumstances some of those particles become real, for a brief period of time. In that sense the vacuum is a warehouse of possible particles.

Close picks up from there and views the vacuum as a medium. Just like any other medium (say, water) it may undergo phase changes. The life of the vacuum then becomes the essential driving force for everything that we observe in our macroscopic lives. The history of the universe than becomes the history of the vacuum.

One property to emerge from the vacuum during such a phase transition is the Higgs field, which gave and still gives mass to particles. Without the Higgs field, all particles would have no mass and travel at the speed of light. One could imagine that, instead of a Big Bang, the universe as we know it was created when a swarm of particles, traveling at the speed of light, entered the Higgs field and was slowed down by it, thereby acquiring masses and becoming the galaxies, planets, rivers, trees and insects that we are familiar with.

The universe is one giant quantum fluctuation of the vacuum. And, of course, this is just one such fluctuation. There might be many others that yielded many other universes.

TM, ®, Copyright © 2011 Piero Scaruffi