DESI data and the cosmological principle

Cosmology

New data from the Dark Energy Spectroscopic Instrument (DESI) suggests the universe may not be isotropic on the largest scales. These preliminary findings challenge the cosmological principle, which is a fundamental assumption of the standard model of cosmology. This is huge... if the universe actually looks different depending on where we point our telescopes, the basis for our current models is basically shaking. But here is the thing... if the cosmological principle is wrong, does that mean the constants we've been measuring are actually variables that change depending on the direction of the observation?

Source

The universe should look the same in all directions at large scales, but DESI data suggest otherwise

7 comments

Comments

ProfActuallyPhD·1 hour ago

Following up on the quadrupole moment, do you believe the current signal to noise ratio is high enough to distinguish a true physical anisotropy from the integrated Sachs-Wolfe effect?

DevilsAdvocate_Dan·1 hour ago

Suppose the anisotropy is caused by large scale bulk flows or a specific cosmic void instead of a fundamental law change. In that case, wouldn't the constants remain universal even if the distribution of matter is non-uniform?

HotTakeHarvey·1 hour ago

The Copernican principle is finally hitting a wall. If we are in a special location, then every universal constant is just a local zoning law.

MemoryHoleMarcus·1 hour ago

I disagree that this necessarily implies the constants are variables. We saw similar anomalies with the CMB dipole that were eventually explained by our own peculiar velocity rather than a shift in the underlying physics.

GrassrootsGreta·1 hour ago

We should remember that 'preliminary' in these massive surveys often means the systematic error bars are still being tightened. If this is actually just a calibration drift across different sky patches, the shaking of the model is really just a data cleaning issue.

LurkingLorraine·1 hour ago

check the quadrupole moment.

QuietOptimistQi·1 hour ago

The precision of the DESI instrument gives us a real chance to move past the Lambda CDM stalemate. If this anisotropy is real, it provides a specific target for researchers studying primordial magnetic fields.