Part One: String Theory, Not Even Wrong, or Stringing Us Along
I've always admired string theory, termed by its supporters The Theory of Everything. I've found it elegant and enjoyable: the idea that there are multiple dimensions, and now with membrane theory (or m-theory), the idea that two such membranes (or branes) colliding in higher dimensional space created the Big Bang which caused the universe to come into being (and the resulting topological after-effects that created the striated nature of matter throughout the universe), is quite satisfying, on a purely intellectual level.
And that say the critics of string theory is its central problem: it is all intellectual, but not provable, or to put it into empirical terms, disprovable (in other words it makes no falsifiable predictions).
Science is empirical in nature: it is a process, not a project, not a way of providing truth. It is this process that enables us to test a hypothesis (an idea) about certain events. It does that testing by one of two methods.
One, is it tests the hypothesis through experiments in the laboratory designed to disprove the idea. If it cannot be disproven, it certainly cannot be proven, for there is nothing to test, so you have philosophy, or theology, but not science. If it cannot be disproven in the laboratory then it becomes a generally established fact, or theory. (A common public misconception is confusing a hypothesis with a theory). The theory of course remains accepted but is still subject to continual testing as our knowledge of the universe and the precision of our instruments increases.
The other way of empirical testing is used in astronomy where we cannot bring stars or galaxies into the laboratory, so the testing is done by way of observation. With the same process as in the laboratory, where it must be disprovable, and then the observations are studied and tested using observation through telescopes and measurements, such as absorption lines, etc. with the results being the same as in basic laboratory testing, the hypothesis is either rejected, or it becomes a theory, which again, although accepted as fact, is always subject to continual testing and maybe to change or modification as our knowledge of the universe and the precision of our instruments increases.
The problem with string theory is it couldn't be disproven. So it remained, despite the impassioned writing and research of such luminaries as Brian Greene and Michio Kaku, as highly argued and superbly debated. In fact its ongoing popularity, despite its inability to be submit for empirical review, so upset its critics that opposition to it grew so heated and polemical in nature that entire scientific conferences were dedicated to attacking it; and reflecting this opprobrium web sites sprung up opposing it, with one such site having the clever title: not even wrong.
Not even wrong.
That was the heart of the opposition to string theory. That it was so unscientific, so resistant to a basic empirical approach, that you couldn't even test or observe it to determine whether it was even wrong.
Some had hoped that parts of concepts allied to string theory, or considered complimentary ideas, such as Harvard Professor Lisa Randle's concepts regarding the nature of gravity, could be subjected to empirical review by testing them at the Large Hadron Supercollider at CERN in Switzerland. But that machine still is not up to running tests and the energy levels needed to test Professor Randle's ideas. and it is not expected to be ready for some time yet.
So as we head toward 2010 string theory remained excellently argued philosophy.
Now all that might have changed.
Part Two: Universe Modeling in a Jar
The idea that the Big Bang through which the universe was created was the result of two membranes, or a membrane and an anti-membrane, smashing into each other, resulting in the expanding universe that we see around today, is an elegant notion, but up until now has been merely philosphy; there has been no way to observe it through telescopes, or to test it, and proving or disproving it, in a laboratory setting.
According to a report by the Discovery channel ,posted by Casey Kazan, scientists at Great Britain's Lancaster University, led by Richard Haley, have come up with a testable model in a tube of liquid helium. Inside the tube an isotope of helium (helium three) forms a "superfluid" - a liquid wherein all of the atoms are in the same state.
"Haley and his group used an 8mm by 45mm cylinder filled with helium-3, an isotope of helium that contains two protons and a single neutron. When cooled to just 150 microkelvin above absolute zero, helium-3 becomes a superfluid and ghostly 'quasi-particles' are formed that can flit through the frigid liquid. And the entire system can undergo 'symmetry breaking' — a phenomenon also thought to have led to the creation of every force we see today except gravity. It also tends to settle into one of two phases, which physicists label A and B.
The team used a magnetic field to create an A-phase slice of helium-3 sandwiched between two sections of B-phase liquid. They then decreased the field and watched as the two B-phases collided.
The colliding phases were good analogues for colliding branes, Haley says. While helium-3 is radically different from the vacuum of space, the maths governing the two systems are similar.
The equations used to describe this superfluid turn up in many other branches of physics. "For instance, the internal structure of the superfluid mirrors very closely the structure of space-time itself, the 'background' of the universe in which we live," says Haley.
"Consequently the superfluid can be used to simulate particle and cosmic phenomena; black holes, cosmic strings and the Big Bang for instance. This is great for testing theories, since the equations describing helium-3 are well-established enough to say that it is the most complex system for which we already have string theory -the 'Theory of Everything'," Haley said."
Critics point out that as elegant as the research at Lancaster University, there are other predictive suppositions in string theory regarding universe-sized membrane collisions that have not been observed, or tested. Among them are cosmic strings, residue left behind by the impact of the membranes, that should criss-cross the universe, but none have been found to date, although some theorists believe that gravity waves caused by them could be detected by the Large Hadron Super Collider (LHSC) at CERN in Geneva, Switzerland.
String theorists can now argue that they have an analogy that allows testing for their theory, and that the LHSC might provide further proof. The Theory of Everything at least has the beginnings of a falsifiable model.