* Atomic clocks: Rubidium is used in atomic clocks, which are the most accurate timekeeping devices in the world. Rubidium atoms are excited to a specific energy level, and the frequency of the radiation emitted as they return to their ground state is used to measure time.

* Rubidium-strontium dating: Rubidium-strontium dating is a method of radiometric dating that is used to determine the age of rocks and minerals. Rubidium-87 decays to strontium-87 with a half-life of 48.8 billion years, so the ratio of rubidium-87 to strontium-87 in a rock can be used to calculate its age.

* Medical imaging: Rubidium-82 is a radioactive isotope that is used in medical imaging. It is used in positron emission tomography (PET) scans, which can be used to diagnose cancer, heart disease, and other medical conditions.

* Industrial applications: Rubidium is also used in a variety of industrial applications, such as in the production of glass, ceramics, and metal alloys.