Quantum mechanics
However, a quantum physicist might argue that something can begin to exist without a cause, from nothing.
Quantum mechanics is a branch of physics concerned with atomic and subatomic systems. It developed because classical physics could not explain the behaviour of matter and radiation at extremely small scales. While classical physics can predict precisely how matter and radiation will behave, quantum mechanics generates only probabilities. Randomness is, therefore, a fundamental characteristic of quantum mechanics. In other words, at atomic scales, events appear to happen without a cause.
Radioactivity
The example given is of radioactive decay of atoms.
Radioactivity is a property of certain atoms with unstable nuclei that spontaneously emit certain forms of electromagnetic energy like gamma rays, and certain subatomic particles like alpha and beta rays. Gamma rays are electromagnetic radiation like radio, light and X-rays. Alpha rays are nuclei of helium atoms, and beta rays are streams of electrons.
Atoms are made up of three subatomic particles:
- protons which are positively charged
- neutrons which are neutral
- electrons which are negatively charged
The mass of an atom is concentrated in its centre, which is called the nucleus, and this consists of protons and neutrons, except for hydrogen, which has only one proton and no neutron.
Whilst quantum mechanics can state precisely what proportion of atoms will decay, it cannot predict which particular nuclei will decay. On the assumption that all the nuclei are in an identical state in the beginning, the decay is, therefore, a random process.
However, this does not mean that the cause is unknown. It only means that the cause cannot be precisely traced to the effect. This is, therefore, a problem of measurement and is not evidence that something can begin to exist without a cause.
Source of radioactive decay
The source of radioactive decay lies in the way subatomic particles are bound together to form the nucleus of an atom.
As mentioned before, hydrogen is made up of a nucleus of one positively charged proton, which binds the sole negatively charged electron together to form the atom.
For atomic nuclei having more than one proton, the positive charges on the protons generate electrostatic repulsion. A nuclear force is, therefore, required to neutralise electrostatic repulsion and bind the nucleus together.