Researchers at the University of Surrey have theoretically demonstrated that two opposing arrows of time can emerge within specific quantum systems. By examining the evolution of entanglement within these systems, they found that while one subsystem experiences time flowing forward as entropy increases, another subsystem can simultaneously experience time flowing backward, with entropy decreasing. This doesn't violate the second law of thermodynamics, as the overall combined system still sees entropy increase. This discovery offers new insights into the foundations of quantum mechanics and its relationship with thermodynamics, particularly in understanding the flow of time at the quantum level.
In a groundbreaking theoretical exploration of the nature of time within quantum systems, researchers at the University of Surrey have posited the possibility of two distinct "arrows of time" coexisting within specific quantum setups. This challenges the conventional understanding of time as a universally unidirectional flow, as dictated by the second law of thermodynamics. The second law dictates that entropy, a measure of disorder, generally increases over time in a closed system. This increase in entropy defines the "arrow of time" we experience, where broken eggs don't spontaneously reassemble, and hot coffee cools down rather than heating up.
The Surrey researchers' work, however, suggests that within certain quantum systems, a localized, reversed arrow of time could theoretically emerge alongside the standard forward-flowing arrow. This doesn't mean time itself reverses, but rather that within these particular quantum systems, entropy might locally decrease, giving the illusion of time flowing backward while the overall encompassing system continues to obey the standard forward arrow of time governed by the second law of thermodynamics.
The theoretical model they employed centers around a quantum system coupled to a large "bath" or environment. By analyzing the evolution of this combined system, the researchers demonstrated the potential for the smaller quantum system to experience a decrease in entropy, effectively exhibiting a reverse arrow of time, while the larger bath continues to experience increasing entropy, maintaining the standard forward flow of time.
This counterintuitive phenomenon arises from the intricate interplay between the quantum system and its environment, specifically through the exchange of heat and energy. As the quantum system interacts with the bath, certain conditions can lead to the transfer of entropy from the system to the bath, effectively reducing the system's entropy and creating this localized reversal of the arrow of time.
This discovery doesn't invalidate the second law of thermodynamics, which continues to hold true for the universe as a whole. Instead, it highlights the nuanced behavior of time within the quantum realm, where the classical laws of physics don't always apply in the same manner. Further research is undoubtedly required to explore the full implications of this theoretical framework, including the possibility of experimentally verifying the existence of these opposing arrows of time and potentially harnessing this phenomenon for technological advancements in quantum computing and other related fields. This intriguing possibility opens a new avenue of inquiry into the fundamental nature of time and its behavior within the counterintuitive world of quantum mechanics.
Summary of Comments ( 81 )
https://news.ycombinator.com/item?id=43072483
HN users express skepticism about the press release's interpretation of the research, questioning whether the "two arrows of time" are a genuine phenomenon or simply an artifact of the chosen model. Some suggest the description is sensationalized and oversimplifies complex quantum behavior. Several commenters call for access to the actual paper rather than relying on the university's press release, emphasizing the need to examine the methodology and mathematical framework to understand the true implications of the findings. A few commenters delve into the specifics of microscopic reversibility and entropy, highlighting the challenges in reconciling these concepts with the claims made in the article. There's a general consensus that the headline is attention-grabbing but potentially misleading without deeper analysis of the underlying research.
The Hacker News post titled "Opposing arrows of time can theoretically emerge from certain quantum systems" linking to a Surrey University news article about a physics paper, has generated a moderate discussion with a mix of skepticism, attempts at understanding, and tangential explorations.
Several commenters express skepticism about the practical implications or the interpretability of the research. One commenter points out the frequent use of "could" and "may" in the article, suggesting a lack of strong conclusions. Another questions the meaningfulness of the findings, asking whether they represent anything more than mathematical curiosities. A further commenter highlights the distinction between theoretical possibilities and experimental verification, implying the reported work is still far from practical relevance.
Some commenters attempt to grasp the core concepts of the research. One asks for clarification on the relationship between the described quantum system and a closed system, a crucial element in discussions of entropy and the arrow of time. Another commenter asks for a simplified explanation, acknowledging the complexity of the topic. This demonstrates a desire within the community to understand the science despite its inherent difficulty.
A few comments drift towards related topics, showcasing the diverse interests sparked by the original post. One commenter notes the prevalence of "two-time physics" in science fiction, touching upon the cultural fascination with temporal manipulation. Another thread discusses the concept of retrocausality, a distinct but related idea that explores the possibility of future events influencing the past. This tangent reveals the broader philosophical implications of time's directionality and our understanding of causality.
Finally, some comments express a general appreciation for theoretical physics, even without fully grasping the specifics of the research. These commenters acknowledge the importance of exploring fundamental questions about the universe, recognizing the value of such investigations even in the absence of immediate practical applications.
Overall, the comments section reflects a mixed reaction to the reported research. While some express excitement and curiosity, others remain skeptical. The discussion highlights the challenges of communicating complex scientific concepts to a broad audience while simultaneously demonstrating the public's enduring fascination with the mysteries of time and the quantum realm.