Scientists have made a groundbreaking discovery using ancient cosmic light to unlock the secrets of dark matter. The Cosmic Microwave Background (CMB), which refers to the first light that freely traveled across the universe, has acted as a treasure map for cosmologists. This light, also known as the “surface of last scattering,” was captured by the upgraded camera SPT-3G on the South Pole Telescope after five years of operations. The initial data collected by SPT-3G hints at exciting future developments in understanding dark matter.
Zhaodi Pan, a scientist with Argonne National Laboratory and the lead author of the research, describes the CMB as a treasure map for cosmologists. Its minuscule variations in temperature and polarization provide a unique window into the universe’s infancy. By studying these variations, scientists can gain insights into the distribution of dark matter.
Dark matter, which makes up 68% of all matter in the universe, does not interact with light like regular matter. However, it does have mass and interacts with gravity. This is where Albert Einstein’s theory of general relativity comes into play. According to general relativity, objects with mass cause a curvature in spacetime. When light passes through this curvature caused by mass, its path is diverted. This effect, known as gravitational lensing, can be used to study dark matter.
Gravitational lensing is used by instruments like the James Webb Space Telescope to observe faint galaxies in the early universe. A more subtle version of this effect, called gravitational microlensing, can be used to study dark matter. To study a web of dark matter across the universe, scientists need a widespread light source, which is where the CMB comes in.
The SPT-3G camera, located on the South Pole Telescope, was able to take advantage of the lack of interference in the atmosphere and remote location to capture the CMB. This investigation not only provided further support for Einstein’s general relativity but also brought scientists closer to understanding the nature and role of dark matter in the universe.
Amy Bender, a physicist at Argonne and a research author, highlights the exciting potential of this study. The result comes from commissioning data when they were just beginning observations with SPT-3G, and the result is already great. With five more years of data to analyze, the future looks promising for uncovering more about dark matter and potentially solving the mystery of dark energy.
Analyzing the data collected by the SPT-3G camera is a painstaking task that takes years, even with the help of dedicated computers. However, every addition of more data brings scientists closer to unraveling the mysteries of the universe. As Bender concludes, “Every time we add more data, we find more things that we don’t understand.” The journey to understanding dark matter and dark energy is a continuous process of peeling back layers and learning more about our instruments and scientific measurements of the sky.
The first results from the SPT-3G camera were published last year in the journal Physical Review D. These results mark an important step forward in our quest to understand the fundamental building blocks of the universe. With further analysis and future developments, scientists are poised to make even greater discoveries in the realm of dark matter and dark energy.
