From Cosmic Mysteries to Quantum Gravity—Exploring the Frontiers of Theoretical Physics

In our lab, we pursue fundamental questions—such as "What is the universe made of?" and "Why does the universe look the way it does?"—through research in cosmology and theoretical physics.

In recent years, cosmology has advanced rapidly thanks to increasingly precise observations, including the cosmic microwave background and large-scale structure. Many key parameters that describe the universe are now measured with high precision. Yet the deeper physical origin of many of these values remains unclear. For example, the nature of dark energy and dark matter—which are thought to make up most of the universe today—remains unknown. Moreover, in inflationary cosmology, which explains how the universe became so large, the origin of the field and vacuum energy that drive inflation is still an open question.

In particular, our lab focuses on the following topics:

• Dark energy
• Dark matter
• Inflation (the early accelerated expansion of the universe)

We study these three central puzzles in cosmology using theoretical and mathematical tools.

Cosmology × Black Holes × Quantum Gravity

Another major pillar of our research is exploring the universe based on quantum gravity. Constructing a theory of quantum gravity that consistently unifies quantum mechanics and general relativity is one of the central goals of theoretical physics. We focus on the origin of the universe and black holes as key arenas for making progress on this problem.

Black holes and the early universe are extreme regimes where gravity and quantum effects both play essential roles. Just as concrete problems—such as blackbody radiation and the hydrogen atom—drove breakthroughs in quantum theory, cosmology and black holes can provide valuable testing grounds for quantum gravity. In our lab, we approach these problems by drawing on a range of frameworks, including string theory and Hořava-Lifshitz gravity.

Learning and Using Diverse Theoretical Tools

Our research often combines two complementary perspectives:

• Low-energy effective field theory: developing controlled, quantum-mechanically consistent arguments based on symmetries and symmetry breaking
• More fundamental theories (including quantum gravity): extracting principle-based predictions and insights

We work across a broad range of areas, including general relativity, quantum field theory, statistical physics, and particle physics.

Who We Are Looking for

• Students who are curious about the universe and black holes
• Students who want to explore questions that go beyond textbooks
• Students who enjoy understanding nature through mathematics and equations
• Students who are willing to study theoretical physics seriously and grow as researchers

We welcome students who are willing to work patiently on open problems. Our topics range from the largest-scale mysteries of the universe to the fundamental principles of physics. If you would like to think deeply about questions whose answers are not yet known, we would be happy to hear from you. Motivated students are welcome; prior research experience is not required.