9/12/09

The man I view as the one of the most responsible for making every physicist's life harder is this guy...

Ernest Rutherford


In 1909, using radium bromide as his radiation source, Rutherford designed an experiment that shot a beam of alpha particles (helium nuclei), onto a sheet of very thin gold foil. Gold, being extremely malleable (look it up), can be pressed extremely thin (only a few hundred atoms thick).

According to what was known up to that time, the atom was composed of negative and positive subatomic particles combined all together in a given space. Because of this, Rutherford's hypothesis was that the alpha particles would just seemly go through the gold foil with little to no deflection due to the fact that the given space with negative and positive subatomic particles would have a net charge of zero. The alpha detector used in the experiment was zinc sulfide, which lights up when hit with an alpha particle.

To his astonishment, that did not happen. While most of the alpha particles did pass through the foil, some (about 1 in 8,000) bounced back (some almost directly).

He spent nearly two years trying to figure out how such results could have been possible. He concluded that for the particles to bounce back, they must have hit something very small and very dense. This caused the picture of an atom to change from a "mish-mosh" of positive and negative subatomic particles to almost what we know of the atom today. This being the positive subatomic particles in the center of the atom (nucleus) surrounded by the electrons orbiting around it. It was years later when Rutherford also aided in the discovery of neutron (the neutral subatomic particle) being the nucleus as well.

Now you might be thinking, how did Ernest Rutherford make everyone's life harder by figuring out atomic structure?

Well, due to the fact that Rutherford found that electrons (the negative subatomic particle) are orbiting the nucleus of the atom, scientists started puzzling themselves about why they weren't being attracted to the positively charged nucleus. This and other phenomena (photoelectric effect and line spectra, among others) led scientists to start generating theories how this might be possible. Through studying the way electrons move around the nucleus (Rutherford's big discovery), Max Planck and Niels Bohr generated the first ideas behind quantum mechanics.

Quantum mechanics is among the most, if not THE most, confusing and non-intuitive theories in all of physics (even Albert Einstein didn't believe in it 100%). Niels Bohr (one of the founding father of quantum mechanics) was quoted as once saying:



"If quantum mechanics hasn't profoundly shocked you, you haven't understood it yet."

I have been and am continuously being shocked by its implications, but greatly respect its ideas. With atoms being one of the things that I feel like I actually understand in this world, I find the theories behind quantum mechanics to be both exciting and headache-causing. Many of my sleepless have been due directly to quantum mechanics.

I will leave you with one of the cornerstones of quantum mechanics as proof of its difficulty. This is the Schrodinger equation. In layman's terms, it is the Newton's Second Law for quantum mechanics.


Fun stuff, huh?

In short, without Ernest Rutherford finding out that electrons orbit the nucleus of an atom, theoretical physicists would have never been able to dream up the Uncertainty Principle, de Broglie relationship, the Schrodinger equation, or any of other fun ideas for aspiring physicists have to learn in order to become one. Not to mention all of the schooling that has to be taught due to the implications of quantum mechanics in relation to modern chemistry. It's easy to draw the conclusion that it is all Rutherford's fault. If he had just believed J.J. Thomson's previous model of the atom, we would not be having these problems.

Although, it's worth pointing out that the only reason we have any modern electronics (including this computer I am typing on) is because of the theories of quantum mechanics. Hmmm, maybe this Rutherford guy isn't so bad after all.

'Til next time...
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