14h 23min, jan 1, 1906 y - Ernest Rutherford
Description:
He discovers that a-particles, when brought to a stop inside a container, become helium atoms. In other words, an a-particle consists of two protons and two neutrons (which is the nucleus of a helium atom) moving at high speed. If and when the a-particle is slowed down and captures a couple of electrons from somewhere, it becomes recognizable as ordinary helium.
The very high speed of the helium nuclei, and the high speed of the electrons (b rays) emitted by radioactive elements, and the high-energy electromagnetic radiation also emitted, and the heat measurements by the Curies, indicate that there is something going on in these elements which is very energetic indeed. But what? Rutherford does not realize that the answer has already been published by Einstein in 1905 (indirectly), in the form of E = mc2.
Added to timeline:
Atomic And Nuclear Physics
Date:
Images:
![]()
