As part of a series exploring the bold new frontiers of science, we caught up Yabebal Fantaye, an expert in cosmology at the African Institute for Mathematical Sciences, to find out why he dedicated his research to searching for anomalies in the cosmic radiation background of the universe.

What is the big problem you're trying to solve?

I have been trying to find observational hints that may help us understand the physical process that shaped the the initial phase of the universe at the Big Bang, as well as the nature of dark energy, an elusive source of an anti-gravity-like force that acts at a cosmological scale, a scale much bigger than many many galaxies combined. The presence of dark energy was confirmed two decades ago by experiments that showed the universe is not only expanding – which has been known since Edwin Hubble’s observation in the late 1920s – but also accelerating. To accelerate at the cosmological scale, the dominant gravity force must be one with anti-gravity nature. In the standard physics, there is no such source – hence the name dark energy.

What is the big idea you're trying to use to solve it?

Following up anomalies in the cosmic microwave background. The cosmic microwave background is the oldest electromagnetic light, a radiation which started its journey as high energy at the time when the universe was only about 400,000 years old and then stretched to low-energy microwave region due to the cosmological expansion of the universe. This radiation fills the entire universe, setting the minimum temperature of its empty space, which is just 2.7 Kelvin!

Since its serendipitous first detection in 1965, the cosmic microwave background data has given us most of the knowledge about the universe. The experiment I was involved in, the European Space Agency Planck satellite mission, has mapped the cosmic microwave background with unprecedented sensitivity, and gave us a wealth of information about the Big Bang, cementing once more the standard cosmological model, which says the Universe is about 13.8 billion years old. Previous observations of the cosmic microwave background data by the NASA WMAP satellite, however, indicated the presence of anomalies that couldn't be explained by the standard model. Given that many of the grand revolutions in physics, including general relativity and quantum physics, came as the result of efforts to explain and understand inconsistencies and anomalies in accepted models, I was interested in exploring these further.

The Planck satellite image of the early universe as seen through the cosmic microwave background. This figure illustrates visually the power asymmetry anomaly: at the largest scales, temperature fluctuations are more extreme in the half of the sky to the right of the gray line than to the left.
Image: ESA and the Planck Collaboration

What has been the most difficult/challenging part of the journey?

Anomalies only become exciting only if statistical fluctuations and systematic errors are excluded as possible origins. Ruling out the systematic errors scenario is easy: one only needs to demonstrate the same anomaly exists in two independent experiments observing the same process. This was the case for us – the WMAP and Planck satellites are independent experiments with completely different observation and instrument designs. What is hard is showing the anomalies are not due to statistical fluctuations, but related to unknown physics, hence opening up a window of opportunity to learn something new.

What is the most shocking fact that people are unaware of?

The connection between cosmology and particle physics. The Big Bang mechanism means that the larger the scale you are probing, a scale as big as the entire universe, the closer you get to its origin, which is governed more by dynamics studied by particle physicists; the very small scale. This is because the universe grew out of small volume whose behaviour is dictated by the quantum world.