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What if matter were only the result of a discrete the order of 10” grams per cubic centimetre of space boundary condition of the space itself, like the feedback and was quickly dubbed "the worst prediction physics iterations that produced the divisions of a fractal? Was has ever made" or "the vacuum catastrophe". he world-space experiencing itself? Were we an To give you an idea of how dense this value is, if you extreme extension of the space looking back at were to take all of the matter we observed in our ourselves and experiencing matter? Einstein seemed to —_- Universe today with billions of galaxies containing hink so, as in his quote: “Physical objects are not in _ billions of stars, most of which are much larger than our space, but these objects are spatially extended. In this | Sun, and we were to stuff them all into a centimetre cube way the concept ‘empty space’ loses its meaning." of space, the density of that cube would only be 10” But if space were the great medium that connected all = grams. This is still some 38 orders of magnitude less hings, gathering information from all places so as to dense than the density of the vacuum. Many scientists self-organise and create the complexity we observed in thought that this figure was ridiculous, and in general it our natural world, then space would ell into obscurity. Even today, some ave to be infinitely dense—infinitely rained physicists are not necessarily dense with information or energy. aware of this value. Throughout the Was this possible, and if so, was there years I've received prompt criticism any evidence as such? | was probing rom certain physicists who either deeper and deeper into tne physics The calculations were unaware ot its crite’ or that had been written and into the simply discarded it, as if the largest experiments that had been performed that were done energy quantity ever predicted could throughout ea 300 years of entailed working ero Pier ignored. sluctuati ; modern physical theory, and | came owever, the vacuum fluctuations o across something significant. out how many energy are crucial to our Pl k' understanding of particle physics at Energy Density of the Vacuum teeny UG hi int th th f P . is point, as they are the source o It seemed that in the quantum world, volume vibrations virtual particle creation at the atomic a difficulty had been encountered could coexist in a level, which is essential to our when physicists tried to calculate current understanding of physics. the energy density of an oscillator cubic centimetre More importantly, in 1948 the such as an atom. It turned out Dutch physicist Hendrik Casimir that some of the vibrations still of space... calculated and elaborated a existed, even when the system The result Was configuration that would ultimately allow an experimental validation of this vacuum energy. Casimir reasoned that if two plates were placed close enough to each other so that the longer wavelengths of the vacuum vacuum. oscillations would be eliminated To understand this better, from between the plates and yet physicists applied a principle of "renormalisation", — would still be present on the outside of the plates, then using a fundamental constant to cut off the number and a minute gradient could be generated where there get a finite idea of how dense the vacuum energy mus would be more pressure on the outside and less on the be, with all its vibrations. The cut-off value used was _ inside, resulting in the plates being pushed together. he Planck's distance or length, named after the grea However, when the distance by which the plates had to physicist Max Planck, who is considered to be the _ be separated to do the job was calculated, it was found ounder of quantum theory. This value is thought to be _ that the plates had to be mere microns apart. This was he smallest vibration possible, being in the order o an impossible task in 1948, and it wasn't until the early 0 centimetres and having a mass-energy in the order 1990s that this experimental test could be done of 10° grams. successfully. The result agreed very well with the The calculations that were done entailed working ou calculations done by Casimir, showing that this energy ow many teeny Planck's volume vibrations could of the structure of space itself is truly present. coexist in a cubic centimetre of space. The answer, So at least the energy was there in the vacuum at the since each Planck's volume had a specific mass, was a quantum resolution. Could it be the energy that mass-energy density that existed in a centimetre cubed connects all things, the energy from which everything of space. The result was enormous! The vacuum energy — emerges and to which everything returns? Well, if so, it density, or what can be called a Planck's density, was in would have to be present at all scales. was brought to absolute zero, where you would think that all the energy would be gone. In fact, the equations showed that there was an infinite amount of possible energy fluctuation even within the enormous! out how many teeny Planck's of space... enormous! 44 «NEXUS JUNE - JULY 2010 The calculations that were done entailed working volume vibrations could coexist in a cubic centimetre The result was www.nexusmagazine.com