100 Years of Cosmic Ray, and the Contribution from Bandung

August this year 2012, the scientific community is celebrating the 100 years of ‘cosmic ray’ discovery. I will not give much on how it’s discovered since already covered on other articles, such as this, this and this. Instead i only discuss about the contribution from a laboratorium in Java, and how the result helping on paving the way to the study of the cosmic ray.

The modern view of cosmic ray study can be seen because of important contribution from experiment of Victor Hess in 1912, using balloon to study the atmosphere and its relation to the electricity. The work of Hess inspires Professor Dr. Jacob Clay from TU Delft, the Netherland; who on 1920 assigned to be a professor in a new Physics Laboratory of Technische Hoogeschool, Bandung, (now Institut Teknologi Bandung) Indonesia. Much of the history of his work in Indonesia already written in here.

Jacob Clay with the balloon experiment in Bandung, 1933

In his earlier tenure for the physics laboratory of Technische Hoogeschool, Clay try to study the ionosphere by sending balloons as high as 30 kms as the one important activity for his lab in Bandung. With his careful and attentive measurement in Java, and in between Java to Netherland during his tenure, both in Technische Hoogeschool and then in Amsterdam, he found that there is a ‘latitude effect’, that is the observed variability of the cosmic ray is depend on the latitude. His works is highly recognized by his colleagues in European, but was not immediately recognized in America. Why was that? During the period of 1920-1930s, the debate about ‘the origin of cosmic ray’ was well known as the debate between Millikan-Compton, as shown here as the headline in the New York Times.

The headline from The New York Times, 1932 about the debate between Millikan and Compton regarding the origin of cosmic ray.

The work of Clay about the latitude effect did not immediately acknowledged by Compton in the 1932, not until the 1935. In 1935 Compton proposes if Clay can win the Nobel Prize for his work, and also the work of Hezz. But the prize went to Hezz and Carl David Anderson for the discovery of positron. Even so Clay never received Nobel prize for his work, but the more important of his finding that is, the very fundamental of cosmic ray; if the primary source of cosmic ray is charged particle, it will be influenced by the magnetic field, which will be observed as varied in different latitude, as the latitude effect, contrary to what Millikan thought about the origin of cosmic ray. In 1939, the works of Clay was well acknowledged by the general community of physics, such his works appeared in Reviews of Modern Physics.

This month, 100 years later, the cosmic ray study has mature enough, and open the window for the study of sub-particle physics, yet still much more to learn. It is the collaborative effort from the scientists around the globe for shaping the study. What we can learn that is, it is not depend on how big or small the laboratory, but more on how we learn from our nature through the passionate and resilient way. For some, Clay might like an unsung hero of cosmic ray, yet, his legacy from his work in Java remains with the physicist in Indonesia, the spirit of exploration and experiment, that inspiring physicists to study and exploring the vast scientific possibilities of our nature.