The "Crisis in Cosmology" Might not be a Crisis After all

The workings of the Universe.
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The "Crisis in Cosmology" Might not be a Crisis After all

Post by fred8615 »

The standard model of cosmology is known as the LCDM model. Here, CDM stands for Cold Dark Matter, which makes up most of the matter in the universe, and L stands for Lambda, which is the symbol used in general relativity to represent dark energy or cosmic expansion. While the observational evidence we have largely supports the LCDM model, there are some issues with it. One of the most bothersome is known as cosmic tension.

It centers on our measurement of the Hubble constant, which tells us the rate at which the universe has expanded over time. There are lots of ways to measure the Hubble constant, from the brightness of distant supernovae, to the clustering of galaxies, to fluctuations in the cosmic background, to the light of microwave lasers. All of these methods have advantages and disadvantages, but if our cosmological model is right they should all agree within the limits of uncertainty.

The problem is, they don’t agree. Back in the early days of cosmology the uncertainty of our measurement was so large that all these results overlapped, but as our measurements got better it became clear different methods gave slightly different values for the Hubble constant. In polite company, astronomers say there is tension between these values.

This tension means that either our measurements are a bit off, or there is something wrong with our model. This has led some astronomers to propose some missing aspects to our model, such as how the mass of neutrinos might realign our Hubble values. But as new measurements of the Hubble constant keep coming in, it looks as if the tension is just getting worse. Now a new paper from Wendy Freedman argues that the tension problem isn’t that bad and that the tension will likely fade as the next generation of telescopes gives us even better data.

Read more: ... after-all/
Frederick J. Barnett
"Someone's got to take the responsibility if the job's going to get done!! Do you think that's easy?!" Gregory Peck - The Guns Of Navarone
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