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How did 20th-century atomic theory challenge the idea that elementary particles are unchanging?
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Atomism
Epicurus, bronze bust from a Greek original, c. 280â270 bce; in the Museo Archeologico Nazionale, Naples.
In the context of atomism, 20th-century atomic theory fundamentally challenged the ancient philosophical assumption that elementary particles are immutable, indivisible, and unchanging.123
This shift occurred through several key scientific developments:
- Discovery of Subatomic Structure: The identification of the electron by J.J. Thomson in 1897 proved that atoms were not the smallest, indivisible units of matter, but were instead composed of smaller, distinct particles.13
- Radioactive Transmutation: Research by Ernest Rutherford and Frederick Soddy demonstrated that radioactivity involves atoms of one element spontaneously transforming into atoms of another, proving that atoms are not indestructible or permanent.13
- Nuclear Dynamics: The discovery of the neutron and the understanding of beta decay revealed that particles like neutrons and protons can change their natureâfor instance, a neutron can disintegrate into a proton, electron, and neutrino.3
Consequently, modern atomic theory views elementary particles as lacking absolute identity, as they can be transformed or reorganized through physical processes, rendering the classical notion of absolute immutability untenable.23