Robert Andrews Millikan

Robert Andrews Millikan – Life, Work, and Memorable Quotes

Learn about Robert Andrews Millikan (1868–1953), the American experimental physicist best known for measuring the electron’s charge and his work on the photoelectric effect. Explore his biography, scientific achievements, controversies, and some of his notable quotations.

Introduction

Robert Andrews Millikan was a leading American physicist in the early 20th century whose experiments helped establish key constants and validate theoretical predictions in quantum physics. Most famously, he is known for the oil-drop experiment, by which he measured the elementary electric charge of the electron. He also conducted precise studies of the photoelectric effect, providing experimental confirmation of Einstein’s theory. Awarded the 1923 Nobel Prize in Physics, Millikan played a pivotal role in shaping modern physics and in the development of Caltech as a scientific powerhouse.

Early Life and Education

Millikan was born on March 22, 1868, in Morrison, Illinois, USA. He was the second son of Silas Franklin Millikan, a Congregational minister, and Mary Jane Andrews. His family had roots in New England, and he spent part of his youth in a rural environment.

He attended Maquoketa High School in Iowa, then entered Oberlin College in 1886, where he earned a B.A. in the classics in 1891. After teaching elementary physics for a time, Millikan pursued graduate study at Columbia University, where he completed his Ph.D. in 1895, with a dissertation titled On the Polarization of Light Emitted from the Surfaces of Incandescent Solids and Liquids.

Academic Career & Institutional Leadership

• After his doctorate, Millikan spent time in Germany (Berlin, Göttingen) to broaden his scientific education.

• He later joined the University of Chicago, becoming a professor and conducting research.

• In 1921, he became Chairman of the Executive Council (effectively the head) at the California Institute of Technology (Caltech), serving in that leadership role until 1945.

• Under his stewardship, Caltech expanded in reputation and research capacity, becoming a major center of scientific work.

• Millikan remained associated with Caltech until his death in 1953, serving also as emeritus professor.

Scientific Achievements

Oil-Drop Experiment & Electron Charge

Millikan’s signature achievement was his oil-drop experiment. Starting around 1908–1909 at Chicago, he and his graduate student Harvey Fletcher suspended tiny, charged oil droplets between electrically charged plates. By balancing gravitational, buoyant, and electric forces, they deduced the electric charge carried by each droplet. Through many observations, Millikan inferred that the charges were integer multiples of a fundamental unit — the charge of a single electron.

His 1913 publication gave a precise value for the elementary charge (although subsequent refinements slightly improved the value).

This experiment not only measured a key constant, but also provided strong empirical support for the quantization of electric charge.

Photoelectric Effect & Planck’s Constant

In response to Einstein’s 1905 paper explaining the photoelectric effect, Millikan conducted experiments to test its predictions precisely. Over about a decade, he built an apparatus to control electrode surfaces and vacuum conditions, confirming the linear relation between photon frequency and emitted electron energy, and validating Einstein’s equation.

Although Millikan initially expressed skepticism about the theoretical interpretation of Einstein’s work, he later acknowledged that the experimental agreement left little room for alternate explanations.

He also used the photoelectric effect method to derive a value for Planck’s constant (h).

Cosmic Rays & Other Work

At Caltech, Millikan turned his attention to cosmic rays, a term he popularized. He believed (incorrectly) that cosmic rays were high-energy photons, which he called “birth cries” of atoms, though later research showed most cosmic rays are charged particles.

His broader experimental work included precision measurements of physical constants and contributions to measurement science.

Honors, Controversies & Later Life

• Millikan was awarded the Nobel Prize in Physics in 1923 for his measurement of the electron charge and his work on the photoelectric effect.

• He also received the Edison Medal and held leadership posts in scientific societies (e.g. President of AAAS) and the National Academy of Sciences.

• Later in life, Millikan was an outspoken Christian theist, arguing for complementarity between science and religion in lectures and writing (notably in Evolution in Science and Religion).

• However, his legacy has faced criticism due to aspects of his behavior and choices:

  1. Data selection debate — historians have argued that Millikan selectively excluded data points in his oil-drop experiments to reduce statistical scatter and inflate precision. Some of his methodological choices are seen as exaggerating certainty.

  2. Eugenics associations — Millikan was involved with the Human Betterment Foundation and held views that, by modern standards, are considered regrettable (e.g. preferences in population composition).

  3. Institutional reckonings — In recent years, Caltech removed his name from buildings and professorships due to his eugenics involvement.

• Millikan died on December 19, 1953, in San Marino, California at age 85.

Personality & Scientific Style

Millikan was meticulous, precise, and ambitious. He valued experimental control and careful measurement. He combined deep religious conviction with scientific inquiry, believing that truth in nature and truth in faith were compatible.

He pursued iconic “big” experiments that could decisively settle theoretical debates (e.g. quantization of charge, verification of Einstein’s photoelectric equation). His inclination toward precision and authority in measurement made him a leading figure in setting standards in physics.

Yet that same confidence sometimes led to controversies over interpretation, data handling, or ethical issues by later standards.

Notable Quotations

Here are a few quotations attributed to Millikan or derived from his writings and speeches:

“Science is only one way of knowing. There are others which may lead to the depths of truth.”

“That which is not measured is not improved.”

“The best teacher is one who suggests rather than dogmatizes, and inspires his listener with the wish to teach himself.”

“The purpose of the study of nature is the explanation of the phenomena of the universe—not just bookkeeping of data, but the formation of general and simple laws.”

These quotes reflect his respect for measurement, humility in pedagogy, and philosophical orientation toward underlying laws.

Lessons from Robert Andrews Millikan

From Millikan’s career and legacy we can draw several lessons:

1. Precision matters in science
   His work underscores how rigorous experiment, careful control of conditions, and painstaking attention to error are critical to scientific progress.

2. Bold experiments can shift paradigms
   The oil-drop experiment and photoelectric studies were decisive in shaping the quantum understanding of nature.

3. Science and values intertwine
   Millikan’s life illustrates both how scientific achievement can coexist with philosophical or religious commitments—and also how ethical scrutiny may revisit the latter.

4. Legacy is complex
   Scientific eminence does not shield one from later reassessment on social, ethical, or methodological grounds.

5. Institutions matter
   Millikan’s leadership at Caltech shows how a strong scientific environment amplifies individual discovery and sustains community impact.

Conclusion

Robert Andrews Millikan was a central figure in early modern physics: his experiments measuring the electron’s charge and confirming the photoelectric effect were instrumental in solidifying foundational constants and validating quantum theory. He was also a builder of institutions, public intellectual, and a figure whose reputation has been reexamined in recent times for his views beyond physics.

His story is a reminder that scientific greatness often comes with complexity, that the pursuit of precision leaves enduring marks, and that the lives of scientists are woven into the fabric of their times.