Scientists Measure the Cosmos with Real Data Rather Than Theory

When it comes to measuring the universe, astronomers often turn to theory rather than real data. Now, though, scientists may have collected enough data to make measuring the cosmos a possibility. For the first time, researchers have measured large distances in the universe with data rather than using calculations related to general relativity.

Previously, scientists have used a "standard ruler" that's been predicted from theoretical models that rely on general relativity to explain gravity at large scales. A standard ruler is an object which consistently has the same physical size, so that a comparison of its actual size to its size in the sky can provide a measurement of its distance to Earth.

"Traditionally in cosmology, general relativity plays a central role in most models and interpretations," said Alan Heavens, one of the researchers, in a news release. "We have demonstrated that current data are powerful enough to measure the geometry and expansion history of the universe without relying on calculations relating to general relativity."

In this case, the researchers used the baryon acoustic oscillation scale as the standard ruler measured in the research. This is a pattern of a specific length which is imprinted in the clustering of matter created by small variations in density in the very early universe. The scientists calculated its length to be 143 Megaparsecs, which is about 480 million light-years, which is similar to accepted predictions.

"There is a big difference between measuring distance and inferring its value indirectly," said Licia Verde, one of the researchers. "Usually in cosmology we can only do the latter and this is one of these rare and precious cases where we can directly measure distance. Most statements in cosmology assume general relativity works and does so on extremely large scales, which means we are often extrapolating figures out of our comfort zone. So it is reassuring to discover that we can make strong and important statements without depending on general relativity and which match previous statements."

The findings reveal that measuring the universe is possible to do so directly. This, in turn, may pave the way for future studies.

The findings are published in the journal Physical Review Letters.

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