London: Researchers has recently used real data rather than theory and calculations related to general relativity to measure the cosmos for the first time.
A research team from Imperial College London and the University of Barcelona has used data from astronomical surveys to measure a standard distance that was central to their understanding of the expansion of the universe.
The research used current data from astronomical surveys on the brightness of exploding stars (supernovae) and on the regular pattern in the clustering of matter (baryonic acoustic oscillations) to measure the size of this 'standard ruler.'
The matter that created this standard ruler formed about 400,000 years after the Big Bang. This period was a time when the physics of the universe was still relatively simple so the researchers did not need to consider more "exotic" concepts such as dark energy in their measurements.
Previously the size of this "standard ruler" has only been predicted from theoretical models that rely on general relativity to explain gravity at large scales. The new study was the first to measure it using observed data.
The standard ruler measured in the research was the baryon acoustic oscillation scale. This was a pattern of a specific length which was imprinted in the clustering of matter created by small variations in density in the very early universe (about 400,000 years after the Big Bang). The length of this pattern, which was the same today as it was then, was the baryon acoustic oscillation scale.
The team calculated the length to be 143 megaparsecs (nearly 480 million light-years) which was similar to accepted predictions for this distance from models based on general relativity.
Professor Raul Jimenez from the University of Barcelona, said that the uncertainties around general relativity have motivated them to develop methods to derive more direct measurements of the cosmos, rather than relying so heavily on inferences from models and for the study they only made some minimal theoretical assumptions such as the symmetry of the universe and a smooth expansion history.
The study is published in Physical Review Letters.
