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AstroChristie t1_j2k068c wrote

Reply to comment by Aseyhe in Is any "movement" visible in the fluctuations of the CMB over time, or does it appear static? by JarasM

Are these scales proportional such that we need to resolve the CMB to a scaled one million times smaller to see changes in a lifetime? Can the CMB even be resolved to a scale that small?

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Aseyhe t1_j2k47iy wrote

That's right, the scales are precisely proportional in that way.

With respect to whether such resolution is possible, I can't say much about the instrumentation side, but I can point out a major physical challenge. According to our calculations, there simply wasn't much structure on very small scales in the early universe, due to diffusion damping. Photons were able to gradually diffuse between hot and cold regions, allowing their temperatures to equalize. This effectively smoothed out the early universe; due to photon travel times, it affected small scales more than large scales.

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wolfram074 t1_j2kcwrc wrote

if 0.07 degrees of arc goes to 50k year time scales, then 0.00007 degrees of arc goes to 50 year time scales, wavelength of 1.9 mm, rayleigh criterion of angle ~= 1.22*lambda/diameter.

I must have done something wrong because I came out to an effective diameter of only 35 meters, we've totally built radio dish networks bigger than that, heck, the EHT made such a big hubbub about planet scale scopes.

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Aseyhe t1_j2khoy7 wrote

Missing the redshift factor (should be ~55 million years), so I guess that would be ~40 km diameter?

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[deleted] t1_j2kthdn wrote

[deleted]

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wolfram074 t1_j2l6f9a wrote

The total surface area doesn't need to be that big, we're definitely in radio wave territory, so synthetic aperture techniques are readily usable. As long as several telescopes are more than 40km apart and have good enough clocks, we can stitch the data together to get interesting things.

I'm guessing the hurdle is most of these measurements need to be space based since all the flag ship data sets are from satellites.

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