A recent map of the universe has added to the ongoing debate about the expansion rate of the cosmos, known as the Hubble constant, and shed some light on the nature of mysterious entity called dark energy. The map was created using data from the Dark Energy Survey, a collaboration of scientists form multiple institutions, including the U.S. Department of Energy's Fermi National Accelerator Laboratory.

Dark energy is the primary cause of the accelerating expansion of the universe, and its nature is one of the biggest mysteries in cosmology. One way to study dark energy is to measure the Hubble constant, which describes how fast the universe is expanding. The map from the Dark Energy Survey provides a new measurement of the Hubble constant that is more precise than previous measurements, but it also deepens the discrepancy between different methods for measuring the constant.

According to the new measurement, the Hubble constant is 68.11 kilometers per second per megaparsec. This means that for every million parsecs (3.26 million light-years) away from us, galaxies are moving away from us at a speed of 68.11 kilometers per second.

However, other methods of measuring the Hubble constant, such as observations of Cepheid variable stars, have yielded different results. These observations suggest that the Hubble constant may be closer to 74 kilometers per second per megaparsec. This discrepancy is a significant challenge for cosmologists and could indicate that our understanding of the universe is incomplete.

"The tension between the different measurements of the Hubble constant has been growing in recent years, and the Dark Energy Survey results have made it even more significant," said Fermilab scientist Josh Frieman, a member of the Dark Energy Survey collaboration. "This discrepancy is a major problem for cosmology, and it is not clear how it will be resolved."

One possible explanation for the discrepancy is that there may be something wrong with our understanding of dark energy or that there may be some new physics that we have not yet discovered. Another possibility is that the different measurement methods are simply not measuring the same thing, and that the Hubble constant may vary depending on the method used to measure it.

"The Dark Energy Survey has made an important contribution to our understanding of dark energy and the Hubble constant," said Frieman. "However, there is still a lot that we don't know, and we will need to continue to study the universe in order to solve the mystery of dark energy and the Hubble constant."