Tuesday, July 19, 2022

Fear and conformism imprison new perspectives on cosmology

The universe is expanding at a rate of about 67.9 km/s for every megaparsec (3.26 million light-years). That is, the expansion of the universe increases by 67.6 km/s for every 3.26 million light-years we look into space, according to Aiola's team. This is in line with the previous result obtained by the Planck space telescope, which estimates the rate of 67.4 km/s per megaparsec (Mpc). 

Both ACT and Planck disagree with most other estimates that use objects that emit light more recent than the CMB, such as supernovae, Cepheid pulsars, and quasars. All of these tend to indicate a rate of around 74 km/s for 1 Mpc. Calculations using the Cepheids as a reference, for example, suggest that the value would be 73.4 km/s for 1 Mpc. The explanation for this discrepancy may seem easy, but it is not. 


Distance measurements across the Cepheids, for example, are often highly reliable. But when it comes to the expansion rate, one cannot say for sure which of the techniques - again, all correct in theory - is providing the correct measurements. If no explanation is found and a definitive answer is not offered, scientists will have serious problems understanding the universe and how things change over time.


 Understanding dark energy itself, the invisible stuff that causes the universe to expand at an accelerating rate, depends on a correct answer.


 So Planck went into space, we stayed on the ground and when you stay on the ground the researchers like all astronomers who don't stick to the theories already proposed have greater precision, look at smaller angular scales, and they don't necessary have to behave the same way.


 The most discrepant differences between the CMB method and the more recent lights method, we still await some more satisfactory explanation. Either one of them - or both - are wrong somewhere, or maybe there's some new physics out there that neither side has understood. For example, expansion can occur at different rates in each part of the universe.

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