Antony Lewis
@cosmologist.info
Professor of cosmology, University of Sussex. CMB, lensing and theory of observations.
The treachery of images is about to get much worse
April 13, 2025 at 10:26 AM
The treachery of images is about to get much worse
The beautiful new ACT CMB spectra are also well fit by ΛCDM. The shifts in parameters adding DESI are slightly unusual, but in an expected direction - there was reason to think the Planck results gave an H0 value that was a statistical fluctuation to the low side.
April 2, 2025 at 8:17 PM
The beautiful new ACT CMB spectra are also well fit by ΛCDM. The shifts in parameters adding DESI are slightly unusual, but in an expected direction - there was reason to think the Planck results gave an H0 value that was a statistical fluctuation to the low side.
It's been an interesting few weeks for cosmology. To me, the new precision BAO data points from DESI look like quite a decent fit to the best-fit (DESI+CMB) standard ΛCDM model (central point in this figure). Shifts in the model parameters (open to solid points) are not that large.
April 2, 2025 at 8:17 PM
It's been an interesting few weeks for cosmology. To me, the new precision BAO data points from DESI look like quite a decent fit to the best-fit (DESI+CMB) standard ΛCDM model (central point in this figure). Shifts in the model parameters (open to solid points) are not that large.
If you use more of the Planck TT so much closer to actual joint, the combined constraint look more like you might expect - here compared to joint with your new DESI all in LCDM. (I think ACT TT is pulling things more towards high H_0 low Omega_m compared to their TE).
March 28, 2025 at 3:07 PM
If you use more of the Planck TT so much closer to actual joint, the combined constraint look more like you might expect - here compared to joint with your new DESI all in LCDM. (I think ACT TT is pulling things more towards high H_0 low Omega_m compared to their TE).
Interesting stuff, congrats - does seem to require phantom DE though! This plot for LCDM doesn't look too bad to me by eye: if the truth were at the intersection, CMB fluctuated 1-2 sigma in the high Omega_m direction (which would not be a surprise, various hints in that direction).
March 19, 2025 at 10:46 PM
Interesting stuff, congrats - does seem to require phantom DE though! This plot for LCDM doesn't look too bad to me by eye: if the truth were at the intersection, CMB fluctuated 1-2 sigma in the high Omega_m direction (which would not be a surprise, various hints in that direction).
also "The Participants reserve the right to take such action as necessary to protect and maximize the value of their economic interests in the Fund" gives wide control? e.g. LLM (so may be wrong) suggests this, unless possibly covered by EU conflict clause
February 26, 2025 at 10:27 PM
also "The Participants reserve the right to take such action as necessary to protect and maximize the value of their economic interests in the Fund" gives wide control? e.g. LLM (so may be wrong) suggests this, unless possibly covered by EU conflict clause
I don’t see much sign of bias, but does refer to X as a “primary source”. Optimist take: LLM’s remain one of better sources of impartial information in the US. Risk: inserting xAI into US govt and gaining market share by making free; manipulate when everyone’s locked in following Twitter playbook.
February 22, 2025 at 9:32 AM
I don’t see much sign of bias, but does refer to X as a “primary source”. Optimist take: LLM’s remain one of better sources of impartial information in the US. Risk: inserting xAI into US govt and gaining market share by making free; manipulate when everyone’s locked in following Twitter playbook.
According to Musk’s xAI latest model, things are going well for them.
February 22, 2025 at 9:26 AM
According to Musk’s xAI latest model, things are going well for them.
I wondered about this. Grok 3 seems not too bad (though note X is “primary source”). But it is the best currently-free model; may try to get market share and in govt, then later can be bend at will. (If trained on X, will have increasing slant anyway).
February 22, 2025 at 8:40 AM
I wondered about this. Grok 3 seems not too bad (though note X is “primary source”). But it is the best currently-free model; may try to get market share and in govt, then later can be bend at will. (If trained on X, will have increasing slant anyway).