Has Physics Taken a Wrong Turn?

Just before the beginning of the 20th century, physics seemed to be all sown up. Newton’s laws of gravitation showed that the planets in their orbits behaved in perfect accord with his mathematical laws, except for a small discrepancy in the path of Mercury, the planet nearest the sun. And in the realm of the small, the electromagnetic force seemed to account for all phenomena, again except for one small detail to do with blackbody radiation. Whereas physicists expected radiation to vary in a smooth fashion, it seemed to vary in discrete jumps, like small packets. In fact Maxwell (known for his equations describing electromagnetism) said “…that, in a few years, all great physical constants will have been approximately estimated, and that the only occupation which will be left to men of science will be to carry these measurements to another place of decimals”. How wrong he was!

In the early 20th century two giants of physics, Albert Einstein and Niels Bohr came along and totally shattered that illusion. All the problems in physics were not solved at all and in fact are far from solved even today.

In the realm of atoms, Max Planck, a German physicist, towards the end of the 19th century, performed a number of experiments which showed that energy came in little bundles. This is regarded as the birth of quantum mechanics. After Planck came Niels Bohr, a Dane who became a professor at the University of Copenhagen. Bohr made major contributions to quantum theory throughout the course of his life, particularly during the first half of the 20th century. Along with Werner Heisenberg he developed the theory which would become known as the Copenhagen Interpretation of Quantum Mechanics. This held sway for many years although today there are many other interpretations of the theory.

On the other hand, in the realm of the very big, Albert Einstein developed two theories, the special and general theories of relativity. The special theory dealt with the speed of light (constant in a vacuum) and his famous energy equation (the amount of energy locked in a lump of matter is equal to the mass of the matter multiplied by the square of the speed of light). This simple equation simply says that not only can energy be transferred into mass and vice versa, but as the square of the speed of light is such a huge number, the amount of energy contained in even a tiny lump of matter is enormous. This led eventually to the development of nuclear energy. The general theory dealt with gravitation solving the niggling problem of the discrepancy in Mercury’s orbit.

However, while in the world of the very large (everything from our everyday knowledge of people, tables and chairs to the universe itself) things seemed to knit neatly into place (however see below), it wasn’t so in the world of the very small, the demesne of the atom. For a start, Heisenberg came up with his uncertainty principle which said that you could not measure two related aspects of a particle, for example, it’s position and velocity, at the same time. If you knew it’s position with extremely high accuracy, you could not know it’s velocity with any certainty and vice versa. And this wasn’t anything to do with the accuracy of our measuring instruments, it was something fundamental to the nature of particles such as the constituents of atoms like electrons and protons and perhaps even to atoms themselves.

And further, every particle exhibited aspects of particles and waves. Depending on how you measured it, it could appear as a wave or a particle. The well known double slit experiment showed this clearly and became known as complementarity.

Furthermore, in the quantum world, because of the uncertainty principle, you could not tell when an atom would decay. You could only give a statistical average. If you had millions of atoms, you could predict how many would decay over a certain time, but not which ones.

This led to the story of Schrodinger’s cat. Erwin Schrodinger was a physicist who came up with an equation which described how a system of many particles would change over time. In the tale of the unfortunate cat, a subatomic particle is placed in a box along with the cat. The fate of the cat rested on whether the particle decayed or not (which probability was fifty-fifty). If the particle decayed it caused a phial of poison gas to be broken which killed the cat. If the particle did not decay, no gas was released and the cat lived. Because the box is sealed you will not know what happened till you open it. Naturally this is only a very simple illustration of the paradox and leaves out a lot of subtle technical details. But it purported to show that until the box is actually opened the cat is neither dead nor alive but in a state of entanglement of the two outcomes, a sort of dead/alive cat. This of course was a thought experiment and was never actually carried out. But it served as a good example of the apparent absurdity of quantum physics.

Einstein took umbrage at this and even though he had been involved in the early development of quantum mechanics (wave/particle duality for example), he was a forceful opponent of it. Legend are his many arguments with Bohr on the subject and he was never reconciled to the theory, dying in 1955. However, as the years wore on and more experiments were done, they tended to support quantum theory. Many more theories were put forward to try and explain what was going on in the quantum world. One physicist quipped that there were as many different theories as there were physicists.

One really crazy theory is the Many Worlds theory first put forward by a physicist called Hugh Everett. Referring back to our famous cat above, this theory basically said that when something in the atomic world can go in one of two (or more) ways, it actually chooses all ways. The universe splits at this point and in one universe the cat lives while in the other the cat dies. This leads to billions and billions of universes which in my opinion is like cracking the proverbial nut with a nuclear bomb! It’s nonsense, yet surprisingly many physicists say it is the correct theory.

Another major problem we have is the fact that general relativity theory and quantum theory cannot be reconciled together and hence we have two theories of the universe. One of the very large and one of the very small, a very unsatisfactory state of affairs. One of the reasons for this is that general relativity regards space as continuous while quantum mechanics does not. If you try and put the mathematics together, you get infinities popping up and this is a serious flaw.

So for many years physicists have been working on trying to marry the two theories together. What popped up was string theory which eventually was able to cope with both general relativity and quantum mechanics within the constraints of the one theory. This was great except for one detail. String theory then (it was first muted around 1970) and string theory today has not one shred of experimental evidence to show for itself. It is purely a mathematical theory. While it may be a beautiful piece of mathematics, it nonetheless remains moonshine. Maybe one day, it is possible, we may find some evidence for it. The Large Hadron Collider (LHC), the biggest particle accelerator in the world, which began operations late last year, will be searching diligently for evidence of strings, but even when it reaches it’s full energy capacity sometime next year, it will still be far short of achieving the energies necessary to show evidence for strings. There may be hints but that is all which can be hoped for.

String theory basically replaces all particles with tiny vibrating strings of energy and depending on their frequency of vibration can reproduce every known particle. This may sound grand, but unfortunately these strings do not exist in normal 3-dimensional space (or 4-dimensional if we add time as a dimension). They exist in 11 dimensions. Other string variants can exist in different numbers of dimensions but 11 seems to be generally agreed. But it doesn’t really matter how many dimensions we speak about because there is no evidence for any of these extra dimensions and besides we are really getting into the realm of science fiction, at least in my humble opinion.

So what is happening? Have we really come up against it when trying to figure out the detailed workings of the universe? Is it too big for us? Can our puny human brains handle it? Since the age of the industrial revolution (and even before) men of science have made great strides in understanding the universe and how it works. They have come a long way in a relatively short time. And the progress has been accelerating all the time. Until now. While great things are still being discovered and achieved in other areas of science, physics seems to have come to a dead stop. The standard model, as it is called, has been with us since the 1950s and 1960s, and while it has been improved and refined, it is still with us. And it only encompasses the theory of the atomic world and does not include general relativity which stubbornly remains outside it’s scope.

The Large Hadron Collider has now been operating for a year or so and has only been ramped up to about half it’s design energy. So far the standard model has been confirmed, but no new physics has been seen. But we will probably have to wait till the LHC reaches it full operating energy next year sometime.

So what are some of the outstanding questions we need to answer in particle physics and cosmology? The usual questions are still with us in quantum mechanics. For example, what is meant by a measurement and does this measurement cause the cat, for example, to leave the dead/live stage and become either dead or alive? Does the act of measurement split the universe into two or more universes (the many worlds theorem)? Is the universe 4-dimensional (including time) or multi-dimensional? Are the smallest items of our universe made of particles or strings? Or maybe something else?

Of course there are also questions still to be addressed in the world of the very large. For example, how did the universe begin? For many years there were two different theories, the Big Bang and the Steady State theories. The Big Bang simply stated that the universe began in a massive explosion from a point millions of times smaller than an atom. Not only was all matter we see around us created in that moment, but also spacetime as well. Before that moment nothing existed, not even time. The joke goes that when St Augustine, one of the early Church Fathers, was asked what was God doing before the creation of the world, he answered that He was preparing Hell for people who asked such idle questions. Of course he didn’t answer so glibly. He actually said that time was a property of the universe that God created when he created everything else, so he wasn’t so far from modern ideas here. On the other hand the Steady State said that the universe always existed and that continuous creation was ongoing to fill out the vacuum left as space expanded. However, this idea was shelved when the radio echo of the Big Bang was discovered coming from every point in the sky.

Once it became generally accepted that the Big Bang was the start of our universe, the questions then became what happened before the Big Bang? What caused the Big Bang? If one Big Bang could occur, where there others? Is there more than one universe? It seems that with every new answer followed a myriad of new questions.

And today, it appears that not only is the universe expanding, but instead of slowing down from the initial kick from the Big Bang, it is actually accelerating. A mysterious substance called dark energy is proposed to be responsible for this acceleration and hence we need to ask what is dark energy. Nobody knows. And to make matters worse, there is also another substance in our universe called dark matter. This is to account for the fact that galaxies should not hold together with the present mass that they contain. At least that we can see and measure, so there must be more mass. This is the dark matter. In fact, our universe as we understand it today consists of 70% dark energy, 25% dark matter which leaves 5% for all the rest, the stars, planets etc. That means we haven’t a clue as to what 95% of our universe is composed of and what’s more, we can’t even see any of it.

And with all our equations, theories etc. there are still many anomalies in our understanding of physics in areas we thought we knew everything about. Like Newton’s laws of motion and gravitation. A pair of unmanned spacecraft called Pioneer 10 and Pioneer 11 were sent on a reconnaissance mission of the planets Jupiter, Saturn and interstellar space, having been launched in 1972 and 1973 respectively. According to known laws of physics, these spacecraft are not where they are supposed to be. They are falling behind in their projected travel by about 5000 kilometers per year. This needs to be explained and much work is being done to address the problem, including adjusting our present theory of gravitation. However, no answers are forthcoming as I write.

Another interesting anomaly is the so called horizon problem. This is asking the question as to how the universe is so uniform no matter in which direction we look. The microwave background radiation which fills the whole universe is at the same temperature everywhere. As nothing can travel faster than the speed of light, there is no way this radiation could have travelled between the most distant parts of the universe to even out the hot and cold spots created in the Big Bang. One wild solution to this was suggested by a physicist called Alan Guth when he came up with an idea called inflation. This says that the universe expanded incredibly rapidly just after the Big Bang in the order of billions of times in billionths of a second. A hairy conjecture which only opens up more questions as to how this might have happened etc.

So it seems to me that the progress (or lack of) modern physics makes, the weirder the answers become. Many worlds, extra dimensions, dark energy, string theory etc. And many of these are pure conjecture with little or no evidence to back them up. Not that I despair of modern physics, it is a most fascinating subject. But it looks like the days are gone (or at least are in abeyance) when new particles were being discovered regularly and theory and experiment went hand in hand. Now experiment is lacking severely behind the theorists who continue to astonish us with their new forays into the unknown.

I should note that I have only scratched the surface of this amazing subject, there is so much more that I could have mentioned. In the meanwhile, we wait for experiments to catch up with theory and hopefully the LHC will ramp up to full energy sooner rather than later. But will it be enough?