Quantum-Atom

Original post date: October 16, 2018

चरमः सद्विशेषणम् अनेको सम्युतः सदा ।
परमाणुः स विज्ञेयो नृणाम् ऐक्यभ्रमो यतः ॥

Don't worry if you can't read Sanskrit. This shloka was given by Sage Maitreya in a famous piece of literature called the Bhagavatam, dating back 5000 years. The meaning, to quote Sage Maitreya, is: "One should know that the ultimate presence of that what shows itself in the manifold as being indivisible, consists of an infinitesimal particle, the combination of which into material forms creates an illusion in man."

This concept of an atom was idealized 5000 years ago, long before John Dalton proposed the first atomic theory. Ever since ancient times, philosophers have imagined what they would get if they kept splitting matter in half until they arrived at an indivisible particle that builds up the entire universe. Dalton's atomic theory stated exactly that: an atom is indivisible, the fundamental building block of everything. That assumption broke when J.J. Thomson discovered the electron and showed that atoms are themselves built from smaller particles.

So, what state of matter is an atom in? Is it a solid sphere, as shown in textbook illustrations? What state is an electron in? These questions get tricky the moment we limit ourselves to the classical states of matter. (There are actually five states of matter. Worth looking up.) An atom is not in any state of matter. It need not be.

To understand that, you need to know how energy and matter are related. Everyone knows E = mc². But what does it really mean? According to special relativity, as matter approaches the speed of light, it becomes heavier. At exactly the speed of light, infinite energy would be required to keep it in motion. Light speed is, for now, impossible to achieve. What also follows is that adding energy to matter increases its mass.

Applying this to the modern atomic model: the atomic realm consists of sub-atomic particles that obey special relativity. The assumed matter carries so much energy that it effectively is a form of energy. This is the same energy released during nuclear fusion.

The atomic world is a strange one. Sub-protonic particles called quarks float around in a void. They disappear and reappear in different locations without tracing any path. That is not magic; it is quantum mechanics.

Electrons are not small spheres orbiting a nucleus. They are theorized to exist somewhere near the nucleus, at all places at once. If you know anything about s, p, d, and f orbitals from chemistry, those letters are not arbitrary. They describe the shape of the orbital, which is the region where an electron is most likely to be found. An s orbital is spherical. A p orbital is dumbbell-shaped, with the nucleus at the centre. The exact location of an electron cannot be determined at any given moment, which is precisely what Heisenberg's uncertainty principle tells us. The electron is not a ball with an orbit. It is a cloud around a nucleus.

An atom, then, is not really matter in the conventional sense. It is closer to energy. This may unsettle some high-school intuitions, but it makes things considerably cleaner for scientists and astronomers. The string theory, for instance, leans on exactly this conception of the atom.

If the smallest world breaks classical physics in favour of quantum mechanics, the largest world does the same. Near cosmic bodies of immense mass, all familiar rules bend. Classical and special relativity step in again, and the pattern repeats at a completely different scale.

Which leads to an interesting thought: is our universe an atom? Is every atom a different universe? Keep wondering.

Originally posted on thedopplerdude.blogspot.com.