Dark Energy Era Phase Transitions
Researchers use CMB data to probe phase transitions in dark energy era
Introduction To Dark Energy Era
The universe is expanding at an accelerating rate, and physicists attribute this acceleration to dark energy, a mysterious component that exerts negative pressure, causing space to expand faster. Dark energy is thought to have become the predominant influence on the universe's evolution around 3–4 billion years ago, at the beginning of what is known as the dark energy era. Researchers have been trying to understand the properties of dark energy and its effects on the universe.
Probing Phase Transitions With Cosmic Microwave Background
Researchers at the University of Notre Dame and Fudan University recently showed that fluctuations in the cosmic microwave background (CMB), small variations in the radiation left over from the Big Bang, could be used to probe phase transitions during the dark energy era. Using this theoretical approach, outlined in a paper published in Physical Review Letters, the researchers examined a hypothetical first-order phase transition (FOPT) occurring after dark energy became predominant and placed limits on how much vacuum energy it could have released. 
Understanding First-Order Phase Transitions
A FOPT is a sudden change from one physical state to another that unfolds through the formation of bubbles and releases energy. The researchers considered whether a hidden part of the universe could have undergone a similar phase transition more recently. According to Seth Koren, one of the researchers, "This is a good place to start testing how well we can see purely gravitational dark sector effects." The researchers used CMB data to probe recent phase transitions and found that if the hypothetical phase transition had occurred uniformly throughout the universe, the energy involved could only be constrained to around 10% of the total dark energy using observations of the universe's expansion.
Implications Of The Research
The research has significant implications for our understanding of the universe and the properties of dark energy. The fact that the researchers were able to place limits on the energy released by a hypothetical phase transition using CMB data is a major breakthrough. As Koren noted, "Our best hope is to look for the cosmological footprint of the dynamics of dark sectors, where the gravitational coupling with our sector may result in observable effects on our particles." The research also highlights the importance of continued exploration of the universe and the development of new technologies to study the properties of dark energy.
Future Outlook
The research is an important step forward in our understanding of the universe and the properties of dark energy. However, there is still much to be learned, and future research will be necessary to fully understand the implications of the findings. As the researchers continue to study the universe and the properties of dark energy, they may uncover new and exciting information that will help us better understand the cosmos. The use of CMB data to probe recent phase transitions is a promising area of research, and future studies may be able to place even tighter limits on the energy released by hypothetical phase transitions.
Sources
This is an original synthesis by Qivorane based on reporting from the outlets below.