The man who feared the floor

In the early hours of March 1911, a man wakes up in his bedroom in London. The sun has only just begun to come out and it is still fairly dark. Careful in his movements, so as to not wake up his wife who is still sound asleep, he sits up on the side of his bed.

He seems to be in his early fifties, hints of aging have only just begun to appear. A wide moustache marks the top of his lips.

He must get back to work urgently, he thinks to himself, the analysis of the experiments may be complete, but he must start writing the research paper soon.

He rubs his eyes and stretches a bit, since his back is sore from sitting in the study all night. His feet still dangle some centimeters from the floor.

He proceeds to stand up, his feet barely touch the ground, and only then does a distant thought dawn on him. He finds himself staring at the floor, quite perplexed, and most definitely stupefied. The feelings inside him are first of curiosity, which subsequently breed concern and the concern, not long after, gives birth to fear. A strange, unnatural and irrational fear.

Even more concerning is the fact that he is a man of science and men of science seldom fear that which needn't be feared. But the floor, the thought of standing on it somehow does make a surge of fear run up his spine, an adrenaline rush, much akin to what is felt by children when they are about to ride a rollercoaster, or perhaps a skydiver, moments before the final jump.

And the thoughts in his mind, indeed were not of superstition, but of science and scientific endeavours, most of which, long preceded the date on which he was conceived, of ideas in natural philosophy thought of by the Greeks and of strange elusive objects born long before the advent of human consciousness on the stage of the universe, or of life on this planet, or of the planet said life was to subsequently appear on.

The subject matter, in fact, came into existence 380,000 years following the birth of the universe as we know it, a mere blink of an eye in the grand scheme of things.

And all of it, culminated in this moment.

This is the story of the man who feared the floor.

And while in all honesty the beginning of the story predates recorded history, the recent and more human part of it, began in ancient Greece, when Democritus first hypothesized the existence of a particle so small that it could not be further subdivided. This, he speculated, was the building block of all matter in the universe and he thus aptly named it atomos which has the literal meaning of "undivided".

But while most philosophers of the time did conceive of ideas that proved to be correct later on in history, this was philosophy for the sake of philosophy and most of these hypotheses were merely speculation. They did not stem from a need to explain observations, nor was there any equipment to make such minute observations at the time, and so for almost two millennia and a couple of centuries, Democritus' atom stayed nothing but that, speculation.

That is until 1803, when John Dalton came up with the first modern rendition of the atomic theory. Dalton believed that the law of definite proportions could be explained if we invoked the idea that elements are made up of tiny building blocks called atoms. The law of definite proportions was an observation made by chemists that elements combined in very definite ratios or proportions to form compounds.

For example if we take 12 grams of carbon, it will react completely with only 32 grams of oxygen to form carbon dioxide, if we took 24 grams of carbon, it would react with no more than 64 grams and so on. This was an enigma at the time.

Atoms of a particular element, according to Dalton, had equal masses and equal sizes, therefore, the law of definite proportions was a direct consequence of the fact that atoms combined to form molecules of compounds and these compounds had very particular configurations of elements. One atom of carbon reacts with one atom of oxygen for example to form a molecule of carbon monoxide and with two molecules of oxygen to form carbon dioxide.

This was Dalton's atomic theory, and even though some of the predictions he made were wrong in that some of the calculated formulas and masses of compounds were inaccurate and also that it predicted that atoms were indivisible, it was still a remarkable theory and in some sense, the start of a revolution in modern physics and chemistry.

The next crucial character in the story of the man who feared the floor was J. J. Thomson, a British physicist, who discovered, during his studies on the discharge of electricity through gases, that the discharge might be caused by particles almost a thousand times smaller than an atom of hydrogen (an atom of hydrogen is basically made up of one proton and an electron).

He discovered a number of properties of these particles, he calculated what their mass might be, what charge they must carry, so on and so forth.

The apparatus he used was more or less as shown in the figure.

He observed that when a tube was evacuated (i.e a vacuum was created inside it by pumping air out) and two electrodes were placed inside it and connected to a very high voltage battery, certain rays (called cathode rays since they originated from the cathode, or the electrode with the negative charge) were produced and seemed to move towards the positive electrode or the "anode". If a hole was punched into the anode the rays would pass straight through the hole and strike a screen which would glow when the rays collided with it.

He established that these rays were a fundamental part of matter because the same rays were produced no matter what gas was used in the tube or what element the electrodes were made of. They always had the same properties.

To check the charge on these cathode rays, he introduced electrodes near the cathode rays and saw that they were deflected in the direction of the positive electrode as shown.

He carried out subsequent experiments to find out other properties of these cathode rays, which he later find out had momentum and therefore were of particle nature.

And so it was established that atoms contained something, and therefore were divisible.

Soon after his discovery, J.J Thomson proposed a model for the atom, which he called the plum pudding model.

It was known at the time that atoms were electrically neutral, that is, they contain equal amounts of positive and negative charges. Therefore, for any possible model of the atom, there had to be a positive charge which countered the charges of the electrons inside the atom. Thomson said that this positive charge was in the form of an evenly distributed positive charge field or "soup" or "pudding" and the electrons in the atom were like plums in the pudding.

The plum pudding model looked more or less as shown in the animation.

And so this theory left room for experimental testing. If the theory survived the testing, it would prevail and be deemed an accurate model for the atom. If it did not, it would have had to be replaced.

One of the people who would go on to conduct some of these tests was Thomson's own student, Ernst Rutherford, a New Zealand born man who studied physics at Cambridge University.

Since Thomson's model had an even distribution of positive charges, the charge density (or the amount of charge in a particular region of the atom) would be very small, and according to Coulumb's law, the greater the charge density in a region of space, the greater the angle with which a charged particle would be deflected by that field. Therefore, if Thomson's model was correct, bombarding a sheet of metal with alpha particles (positively charged particles with mass) would deflect the particles by no more than a fraction of a degree.

Rutherford was old at the time he came up with this idea and so he did not have the resilience anymore to carry out such a long and rigorous experiment that required such minute observations. In 1906, Rutherford was visited by the German physicist Hans Geiger and his graduate student Ernest Marsden. Rutherford, together with Geiger, designed the apparatus for the experiment and Geiger and Marsden carried them out at Rutherford's behest at the University of Manchester where Rutherford was Langsworthy Professor of Physics. The core idea of the experiments was that if a very thin sheet of metal was placed in the path of the alpha particles and if Thomson's model was correct, the alpha particles would either pass straight through, or be deflected by very minute angles of around 0.1 degrees. The metal chosen was gold because it is very easy to hammer it into extremely thin sheets (almost a thousand atoms thick). 

And the experiments, conducted between 1908-1913 had results that were radically different than the ones predicted by Thomson. Not only did the alpha particles get deflected by angles greater than 0.1 degrees, they were even reflected backwards at angles greater than 90 and some even bounced straight back. The results were very contradictory to the notions about atoms and as Rutherford himself said,

It was quite the most incredible event that has ever happened to me in my life. It was almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you

It took some time for Rutherford to finally come up with an explanation for these phenomena and he eventually did ..... because Ernest Rutherford was the man who discovered the atomic nucleus. This was his interpretation of the results:

Rutherford proved that most of the atom is nothing more than empty space. In fact, if you scaled an atom to the size of a football stadium, the nucleus would be at the center, the size of a tiny marble.

And we never stop to consider the implications of this fact, because if an atom is nothing more than empty space, then so are we, for we are made up of atoms too, and so we are nothing but nuclei separated by vast distances of empty vacuum.

Ernest Rutherford was the man who feared the floor that morning, because he realized his discovery implied that the floor had the illusion of solidity..... and he was careful not to tread on it, lest he should fall through.