1 Corinthians 3:19
"Given how unfathomably large the universe is, it is perhaps understandable that we haven’t yet cracked all its secrets. But there are actually some pretty basic features, ones we used to think we could explain, that cosmologists are increasingly struggling to make sense of.
Recent measurements of the distribution of matter in the universe (so-called large-scale structure) appear to be in conflict with the predictions of the standard model of cosmology.....But there are more radical solutions. These include rethinking the nature of dark energy (the force causing the universe’s expansion to accelerate), invoking a new force of nature or even tweaking Einstein’s theory of gravity on the largest of scales.
What has changed recently is that our measurements of large-scale
structure, particularly at very late times, have significantly improved in their precision. Various surveys such as the Dark Energy Survey and the Kilo Degree Survey have found evidence for inconsistencies between observations and the standard model.
In other words, there is a mismatch between the early time and late time fluctuations: the late-time fluctuations are not as large as expected. Cosmologists refer to this clash as the “S tension”, as S is a parameter that we use to characterize the clustering of matter in the late-time universe.
Depending on the particular data set, the chance of the tension being a statistical fluke may be as low as 0.3%. But from a statistical point of view, that is not enough to firmly rule out the standard model.
However, there are strong hints of the tension in a variety of independent observations. And attempts to explain it away due to systematic uncertainties in the measurements or modelling have simply not been successful to date.
For example, it had previously been suggested that perhaps energetic non-gravitational processes, such as winds and jets from supermassive black holes, could inject enough energy to alter the clustering of matter on large scales.
However, we have shown using state-of-the-art cosmological hydrodynamical simulations (called Flamingo) that such effects appear to be too small to explain the tension with the standard model of cosmology.
If the tension is indeed pointing us to a flaw in the standard model, this would imply that something in the basic ingredients of the model is not correct.
This would have huge consequences for fundamental physics. For example, the tension may be indicating that something is wrong about our understanding of gravity, or the nature of the unknown substance called dark matter or dark energy. In the case of dark matter, one possibility is that it interacts with itself via an unknown force (something beyond just gravity)."
"Given how unfathomably large the universe is, it is perhaps understandable that we haven’t yet cracked all its secrets. But there are actually some pretty basic features, ones we used to think we could explain, that cosmologists are increasingly struggling to make sense of.
Recent measurements of the distribution of matter in the universe (so-called large-scale structure) appear to be in conflict with the predictions of the standard model of cosmology.....But there are more radical solutions. These include rethinking the nature of dark energy (the force causing the universe’s expansion to accelerate), invoking a new force of nature or even tweaking Einstein’s theory of gravity on the largest of scales.
What has changed recently is that our measurements of large-scale
In other words, there is a mismatch between the early time and late time fluctuations: the late-time fluctuations are not as large as expected. Cosmologists refer to this clash as the “S tension”, as S is a parameter that we use to characterize the clustering of matter in the late-time universe.
Depending on the particular data set, the chance of the tension being a statistical fluke may be as low as 0.3%. But from a statistical point of view, that is not enough to firmly rule out the standard model.
However, there are strong hints of the tension in a variety of independent observations. And attempts to explain it away due to systematic uncertainties in the measurements or modelling have simply not been successful to date.
For example, it had previously been suggested that perhaps energetic non-gravitational processes, such as winds and jets from supermassive black holes, could inject enough energy to alter the clustering of matter on large scales.
However, we have shown using state-of-the-art cosmological hydrodynamical simulations (called Flamingo) that such effects appear to be too small to explain the tension with the standard model of cosmology.
If the tension is indeed pointing us to a flaw in the standard model, this would imply that something in the basic ingredients of the model is not correct.
This would have huge consequences for fundamental physics. For example, the tension may be indicating that something is wrong about our understanding of gravity, or the nature of the unknown substance called dark matter or dark energy. In the case of dark matter, one possibility is that it interacts with itself via an unknown force (something beyond just gravity)."
ZMEScience
