Expert: Philip A. Stahl - 2/6/2011

Question
Hi, hope you can help me and that this is not a silly question. firstly, it has been prompted by an old saying of my fathers(though where it acme from he cannot say) "LITTLE FISH HAVE BIGGER FISH UPON THEIR TAILS TO BITE THEM, BIGGER ONES HAVE BIGGER STILL AND SO ADD INFINITUM" it got me thinking that the structure of our solar system seems to be similar to that of an atom ie. a shield of electrons (the planets) around a core of protons and neutrons ( the sun ). therefore is it possible that our solar system is only one atom in a larger molecule which is our galaxy, which is in turn a part of something larger> the universe?
Sorry for the long winded question

Regards and thanks for making yourself available to curious lay people such as myself

St. John

Answer
Hello,

The old "solar system" (Bohr model) of the atom basically fell through once the modern wave mechanics form arrived (ca. 1925-26, compliments of Werner Heisenberg and Erwin Schrodinger et al). Even worse, the Bohr model suffered because of the fact that the accelerating charge (electron of hydrogen atom) couldn't be sustained in any orbit without drastic consequences.

For example, from basic physics, we know that as such an electron moves round the nucleus it would have to release electro-magnetic (EM) radiation. However, if it does so it must lose energy thus can't sustain its "orbit speed" and must therefore spiral into the nucleus. Hence, the system can't be sustained - not even for a micro-second.

Why is this primitive model still taught? Well, because it conforms more or less to a model most people can already grasp: that for the orbiting planets of the solar system. But there is actually no remote analogy when explores deeply. Planets aren't electrons, and vice versa, nor are the forces applied similar (electrostatic attraction is not the same as gravitational attraction).

In the model based on modern quantum mechanics, electrons have no precise location (x,y,z) in an atom. Hence, one can't write or speak of an electron's position only of its probable position.

For different quantum numbers (e.g. n, l, m(s) etc.) there are differing probabilities for the electron to appear under differing hydrogen atom configurations, for example.

You can get an idea of the appearance of differing atomic orbitals - say for the H-atom, at this site:

http://www.chemguide.co.uk/basicorg/bonding/orbitals.html

The bottom line: there is no analogy whatever between solar system and even the simplest atomic system. Any misconceptions on this are predicated on the extreme simplicity of that early Bohr model, which has since been found to have only limited use (like to find some frequencies and energy levels for the H-atom).