On the SLOAN webpage, there’s a list of ongoing and completed surveys, some of which went out to z=3 (10 billion years ago/away), though the more distant ones didn’t use stellar emissions as output. Here is a youtube video visualizing the data that eBOSS (a quasar study) added in 2020, but it shows it alongside visible/near-infrared galaxy data (blue to green datasets), which go up to about 6 billion years. Radial variations in density in the observed data can be explained by local obstructions (the galactic plane, gas clouds, nearby galaxies), while radially symmetric variations can be explained by different instruments’ suitability to different timescales.
Just eyeballing it, it doesn’t look like there are any spherical irregularities more than 0.5 billion light years across.
If you want to look more carefully, here are instructions for downloading the dataset or specific parts of it.
You should also note that Dyson spheres aren’t just stars becoming invisible. Energy is conserved, so every star with a Dyson sphere around it emits the same amount of radiation as before, it’s just shifted to a lower part of the spectrum. For example, a Dyson sphere located at 1 AU from the Sun would emit black body radiation at about 280 K. A Dyson sphere at 5 AU would be able to extract more negentropy at the cost of more material, and have a temperature of 12 K—low enough to show up on WMAP (especially once redshifted by distance). I actually did my Bachelor thesis reworking some of the math on a paper that looked for circular irreglarities in the WMAP data and found none.
On the SLOAN webpage, there’s a list of ongoing and completed surveys, some of which went out to z=3 (10 billion years ago/away), though the more distant ones didn’t use stellar emissions as output. Here is a youtube video visualizing the data that eBOSS (a quasar study) added in 2020, but it shows it alongside visible/near-infrared galaxy data (blue to green datasets), which go up to about 6 billion years. Radial variations in density in the observed data can be explained by local obstructions (the galactic plane, gas clouds, nearby galaxies), while radially symmetric variations can be explained by different instruments’ suitability to different timescales.
Just eyeballing it, it doesn’t look like there are any spherical irregularities more than 0.5 billion light years across.
If you want to look more carefully, here are instructions for downloading the dataset or specific parts of it.
You should also note that Dyson spheres aren’t just stars becoming invisible. Energy is conserved, so every star with a Dyson sphere around it emits the same amount of radiation as before, it’s just shifted to a lower part of the spectrum. For example, a Dyson sphere located at 1 AU from the Sun would emit black body radiation at about 280 K. A Dyson sphere at 5 AU would be able to extract more negentropy at the cost of more material, and have a temperature of 12 K—low enough to show up on WMAP (especially once redshifted by distance). I actually did my Bachelor thesis reworking some of the math on a paper that looked for circular irreglarities in the WMAP data and found none.