Billions of years ago, our very existence was determined by an extremely hot and dense sea of neutrons and electrons that combined together to form a single atom — hydrogen. From that hydrogen, stars and galaxies began to form, and planetary worlds began to take shape.
Astronomers have pondered the birth of the universe for centuries, but it's been difficult to determine exactly when this primordial soup of particles was born.
However, an international team of researchers now believe that they have gotten an accurate measurement of the age of the universe. They did this by looking at the cosmic "baby photos."
The research team included scientists from 41 institutions in seven countries who relied on observations by the Atacama Cosmology Telescope (ACT) in Chile. Their findings confirmed that the universe dates back 13.8 billion years ago, based on the afterglow left over by the Big Bang.
The results were published Tuesday in the journal Cosmology and Nongalactic Astrophysics.
In order to estimate how old the universe is, the researchers looked back at when it all began. They measured the oldest light emitted by the cosmos in order to obtain the best image of a young, baby universe.
"We are restoring the 'baby photo' of the universe to its original condition, eliminating the wear and tear of time and space that distorted the image," co-author Neelima Sehgal, an associate professor Stony Brook University's Physics and Astronomy Department, explained. "Only by seeing this sharper baby photo or image of the universe, can we more fully understand how our universe was born."
The researchers relied on the cosmic microwave background, or the electromagnetic radiation that's been left behind from the early years of the universe, in order to create this new image of the universe in its infancy.
The light, emitted 380,000 years after the Big Bang, varies in polarization — this is represented by redder or bluer colors. The team used the spacing between these variations in order to calculate a new estimate for the age of the universe.
How old is the universe?
Previous estimates of the universe's age relied on NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) and the European Space Agency's (ESA) Planck Space Telescope.
In 2013, ESA's Planck telescope estimated that the universe is 13.82 billion years based on the most detailed map ever created of the cosmic microwave background. Meanwhile, WMAP launched in the year 2001 to measure the difference in temperatures across the skies in the cosmic microwave background.
In 2016, NASA announced that the universe is 13.77 billion years old according to data from WMAP.
However, in 2019, a study suggested that the universe may actually be 2 billion years younger than previously believed. That study used the movement of the stars to estimate the rate of expansion for the cosmos and suggests the universe has actually been expanding faster than previously thought, and therefore, reached its current size at a quicker rate.
“Now we’ve come up with an answer where Planck and ACT agree,” lead author Simone Aiola, a researcher at the Flatiron Institute’s Center for Computational Astrophysics in New York City, said. “It speaks to the fact that these difficult measurements are reliable.”
The new study also calculates a new measurement for the Hubble Constant.
The universe expansion rate is measured through the Hubble Constant, which is calculated by comparing the galaxies' distances to the apparent rate of recession away from Earth.
The study suggests a Hubble constant of 67.6 kilometers per second per megaparsec, which means that an object located 1 megaparsec around 3.26 million light-years away from Earth, is moving away from us at 67.6 kilometers per second as the universe continues to expand.
Astronomers are hoping to use this data to further examine how the universe came to be, and its rate of expansion.
Abstract: This paper presents an algorithm for generating temperature and polarization maps that have the best features of both Planck and ACT: Planck's nearly white noise on intermediate and large angular scales and ACT's high-resolution and sensitivity on small angular scales. We use this approach to combine data from the 2008--2018 ACT observing seasons with the full Planck maps to generate temperature and polarization maps that cover over 18,000 square degrees, nearly half the full sky, at 100, 150 and 220 GHz. The maps reveal 4,000 optically-confirmed clusters through the Sunyaev Zel'dovich effect (SZ) and 18,500 point source candidates at >5σ, the largest single collection of SZ clusters and millimeter wave sources to date. The multi-frequency maps provide millimeter images of nearby galaxies and individual Milky Way nebulae, and even clear detections of several nearby stars. Other anticipated uses of these maps include, for example, thermal SZ and kinematic SZ cluster stacking, CMB cluster lensing and galactic dust science. However, due to the preliminary nature of some of the component data sets, we caution that these maps should not be used for precision cosmological analysis. The maps will be made available on LAMBDA no later than three months after the journal publication of this article.