The Intriguing Quest for Knowledge in Physics: Exploring Unanswered Questions and Unsolvable Mysteries

Physics, with its vast array of unanswered questions and unsolvable mysteries, keeps many physicists, including myself, up late at night. These queries range from the grand existential questions such as whether we are alone in the universe and the cause of our existence, to the seemingly mundane but profound ones about the behavior of nanocrystals. This article delves into some of these intriguing questions and the relentless pursuit of understanding them.

The Cosmic Questions

In about 80 billion years, our universe will be in a very different state. With very few stars remaining and the vast distances between the few that do remain, one can only wonder what fate awaits the human race. Will it still exist, or will it face extinction?

These cosmic questions, while unanswerable, drive the curiosity that keeps physicists engaged and motivated. Often, no matter the scale, the pursuit of understanding appears to be the driving force behind this exploration. These unsolved mysteries and the pursuit of answers are what make the scientific community thrive.

Unraveling the Mysteries of Nanocrystals

One of the less grandiose yet intriguing areas of my professional life involves the study of lead sulfide (PbS) nanocrystals. These particles come in two varieties: the "red PbS" and the "black PbS." While the black PbS variety has been extensively studied, the red PbS variant's red color remained a mystery for many years.

Why did the red PbS nanocrystals exhibit a red color, and why did researchers stop studying them in favor of the black variant? This question fascinated me, leading me to revisit the topic with a chemistry PhD student. Together, we successfully synthesized a new surface ligand that seemed to replicate the red PbS spectrum. This breakthrough was the first hint that the color was related to the surface ligand and could be systematically controlled. Unfortunately, this research was halted due to unforeseen circumstances. The mystery of red PbS remains one of the most baffling queries in my work.

A related mystery involved the black PbS nanocrystals. We discovered a unique phenomenon: the color of the solution would change from a very dark green to a much lighter shade as the solution warmed. This led to the development of a cryogenic absorption spectroscopy apparatus to study the changes in absorbance. We found a profound hysteretic bistability, which, according to my hypothesis, was due to the surface ligand switching from a disordered to an orderly state. This discovery opened new avenues for understanding the role of ligands on nanocrystal absorbance.

Shining Light on Copper Selenide (CdSe) Nanocrystals

Another fascinating area of research was the spectroscopy of copper selenide (CdSe) nanocrystals. We encountered complex spectral data that could be directly linked to theoretical models. Our collaboration with a chemist involved the growth of high-quality nanocrystals in his lab. One particularly intriguing moment occurred when we received a batch of supposed spherical nanocrystals that had the same spectroscopy as our commercial batch of rod-shaped crystals. However, further examination revealed that the supposed spherical crystals were actually zincblende crystals, not wurtzite as we had suspected. This misidentification led to a significant breakthrough in our understanding of the crystal phases of these nanocrystals.

These explorations into the minutiae of nanocrystals and their behavior have not only provided valuable insights but have also resulted in published works that have contributed to the broader scientific community. From the color changes in PbS nanocrystals to the spectroscopic properties of CdSe nanocrystals, the pursuit of understanding these phenomena has been a bleeding-edge pursuit of knowledge and a testament to the immense value of scientific curiosity.

My quest for understanding these mysteries is driven by a desire to open new fronts of knowledge that may or may not find practical applications. However, the sheer pursuit of knowledge, the bloody-minded determination to uncover the truth, is what keeps me engaged and motivated. This pursuit is a reflection of the intrinsic value of scientific inquiry and the importance of staying curious.

In summary, the mysteries of the universe and the unexplainable questions in nanocrystal research are the fuel behind my passion for physics. The relentless pursuit of understanding these phenomena is a journey that continues to challenge and inspire me. These are the small but significant parts of the universe that I face in the lab, and my dedication to unraveling their secrets is a reflection of the fundamental drive to discover and understand the world around us. The path may be winding and the answers may remain elusive, but the journey is the most rewarding part.