Pioneer in Practical Applications of Electromagnetism
Introduction
Niels Bohr (circa 1885-1962) was a Danish physicist who made foundational contributions to understanding atomic structure and quantum theory. He received the Nobel Prize in Physics in 1922.
Early Life and Education
Bohr was educated at Gammelholm Latin School, starting when he was seven. In 1903, Bohr enrolled as an undergraduate at Copenhagen University. His major was physics, which he studied under Professor Christian Christiansen, the university’s only professor of physics at that time.
Contributions
Niels Bohr regarded the “duality paradox” as a fundamental or metaphysical fact of nature. A given kind of quantum object will exhibit sometimes wave, sometimes particle, character, in different physical settings. He saw such duality as one aspect of the concept of complementarity. Bohr regarded renunciation of the cause-effect relation, or complementarity of the space-time picture, as essential to the quantum mechanical account.
Because of the difference of views between Bohr and Werner Heisenberg, the main sources of the so-called Copenhagen interpretation, the position of that interpretation on wave–particle duality is ill-defined.
Bohr’s Orbit Theory (circa 1913)
Bohr developed the Bohr model of the atom, in which he proposed that energy levels of electrons are discrete and that the electrons revolve in stable orbits around the atomic nucleus but can jump from one energy level (or orbit) to another.
In atomic physics, the Rutherford–Bohr model or Bohr model depicts the atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus, similar in structure to the solar system, but with attraction provided by electrostatic forces rather than gravity.
After the cubic model (1902), the plum-pudding model (1904), the Saturnian model (1904), and the Rutherford model (1911) came the Rutherford–Bohr model, or just Bohr model for short (1913).
The improvement to the Rutherford model is primarily a quantum physical interpretation. The Bohr model has been superseded, but the quantum theory remains sound. The model’s key success lay in explaining the Rydberg formula for the spectral emission lines of atomic hydrogen. While the Rydberg formula had been known experimentally, it did not gain a theoretical underpinning until the Bohr model was introduced.
Although the Bohr model has been supplanted by other models, its underlying principles remain valid. He conceived the principle of complementarity: that items could be separately analyzed in terms of contradictory properties, like behaving as a wave or a stream of particles. The notion of complementarity dominated Bohr’s thinking in both science and philosophy.
Bohr Radius
The Bohr radius (a0) is a physical constant, approximately equal to the most probable distance between the proton and electron in a hydrogen atom in its ground state.
It is named after Niels Bohr, due to its role in the Bohr model of an atom.
Its value is 5.2917721092(17)×10-11 m.
Quotes
“Anyone who is not shocked by quantum theory has not understood it”, “An expert is a man who has made all the mistakes which can be made in a very narrow field”, and “Never express yourself more clearly than you are able to think”
“Everything we call real is made of things that cannot be regarded as real.”
What did Bohr say to Einstein?
He told Niels Bohr that “God does not play dice”, to which Bohr responded with, “Stop telling God what to do.” Einstein was using “God” as a metaphor for the entity who creates the laws of nature, which in this case was the scientific community present at this conference.
Vision
Bohr’s contributions to atomic physics and quantum theory were profound. His ideas continue to be essential to our understanding of the nature of matter and energy.
Legacy
Henry’s contributions to science are widely recognized. He was highly regarded in his lifetime and beyond. The SI unit of inductance, the henry (H), is named in his honor. His work laid the groundwork for many subsequent developments in electrical technology.