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O experimento demonstrou que, ao observar as mudanças na entropia entre essas duas regiões, os cientistas puderam reconstruir a sequência dos eventos sem a necessidade de um relógio externo. Isso sugere que o tempo pode ser uma propriedade emergente de sistemas quânticos isolados, oferecendo novas perspectivas para a compreensão da natureza do tempo no universo.
The central point is that the atoms could cross the barrier between these two regions, but the system as a whole remained isolated from the external environment. Thus, the researchers could monitor what was happening inside the bright sector and investigate if the order of events could be defined only by internal changes.
In the bright sector, the atomic cloud expanded and then collapsed repeatedly. Therefore, the scientists compared this behavior to cycles similar to a Big Bang and a Big Crunch, in an analogy with cosmological scenarios in which the universe expands and then contracts.
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Brazilian students created a $1 filter using pine bark, cotton, and 3D-printed parts to clean cassava wastewater, reduce the toxicity of a hazardous waste, and transform contaminated water into biofertilizer.
The problem of time appears when physics tries to merge relativity and quantum mechanics
The experiment touches on an important impasse in modern physics. General relativity describes gravity and the structure of space-time on a large scale, while quantum mechanics describes particles and fields on microscopic scales. Both theories work very well in their own domains, but they do not yet completely fit together.
One of the obstacles is precisely the role of time. In some formulations related to quantum gravity, such as the Wheeler-DeWitt equation, the Universe does not have an external clock. This creates a difficult question: if there is no time coming from outside, how do we know what happens before and after?
According to the scientific article signed by Giovanni Barontini, the goal was to test relational constructions of time using cold atoms. In this view, time does not need to be an independent entity; it can emerge from the relationships between parts of the system itself.
It’s a change of perspective. In everyday life, we are used to thinking of time as something that runs independently, marked by clocks, calendars, and predictable movements. In fundamental physics, however, this notion may not be so simple.
Entropic time emerges when the distribution of atoms changes
The most important part of the experiment is in the so-called entropic time. This concept was used to describe an internal sequence of events based on the entropy of the bright sector, that is, in the way the atoms spread and reorganized within the observed region.
When the distribution of particles changed, the system could be read as if it were advancing in time. When this distribution showed no significant change, the internal time practically stopped advancing in that model.
This reading allowed the correct ordering of events in the mini-universe, even during cycles of expansion and collapse. This is important because, in systems that grow and shrink, a simple variable, such as size or position, does not always point to a unique direction for time.
The experiment also indicated that entropic time could speed up or slow down as entropy changed. In other words, the passage of time within the model depended on the pace of internal transformations, not on a bench clock.
This result reinforces a powerful idea: perhaps what we call time, in certain physical contexts, is not a fundamental piece placed from outside, but a property that appears when parts of a system relate and change.
Result does not prove how the real Universe works, but opens a new experimental window
Despite the impact of the discovery, it is important to avoid exaggerations. The mini-universe created in the laboratory is an analog platform, not a complete replica of the cosmos. It serves to test mathematical and physical ideas in a controlled environment, with variables that researchers can manipulate.
The value of the study lies precisely in this possibility. Questions about the origin of time, the time arrow, and the relationship between entropy and quantum gravity are often difficult to test directly because they involve cosmic scales or extreme conditions from the beginning of the Universe.
With ultracold atoms, lasers, and optical traps, scientists can create simplified versions of these problems. This allows observing patterns, comparing theoretical predictions with experimental data, and adjusting models that were previously restricted to paper.
The study also showed that a version of the Schrödinger equation, one of the foundations of quantum mechanics, can be written using this internal time. This suggests that entropic time is not just a metaphor, but a variable capable of organizing the evolution of the observed system.
Even so, the limits of the experiment itself need to be remembered. The physics of the real Universe involves gravity, cosmic expansion, dark matter, dark energy, and numerous components that are not present in a system of 24,000 rubidium atoms.
Next tests may involve more complex systems and new quantum simulations
The advancement opens the way for new experiments with more sophisticated systems. One possibility is to investigate whether entropic time continues to function when more complex quantum phenomena, such as entanglement and stronger interactions between particles, come into play.
There is also interest in using similar platforms to study analogies with black holes, Big Bang scenarios, Big Crunch, and models in which the Universe would not have a simple initial singularity, but some type of quantum “leap.”
This type of research is not expected to bring immediate applications to everyday life, such as a new clock or ready commercial technology. The impact lies in the foundation of knowledge, in the effort to understand how fundamental laws can describe the passage of events without relying on an external observer.
For cosmology and quantum physics, this is relevant because it helps transform philosophical questions into measurable tests. The experiment shows that ideas about time can be put to the test in the laboratory, even when they originate in theories about the entire Universe.
If confirmed and expanded, this path may help scientists better understand why we feel time moving from the past to the future, while many fundamental equations seem to work almost the same way forwards and backwards.
In the end, Birmingham’s mini-universe does not close the discussion about time. But it puts a provocative hypothesis on the table: perhaps time, in its deepest form, does not need a clock to exist.
The experiment raises a question that may divide opinions: is time a fundamental feature of reality or just something that arises when there is change and disorder? Leave your comment and say if this discovery changes the way you see the Universe.
