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28 microns is the peak wavelength emitted by a black body at 105°K, or -270°F. This corresponds to extremely old, red-shifted light.

Help me out here (you are obviously very up-to-date on your Cosmology - at least in comparison to me).

The current black-body temperature (temperature inferred from the frequency of the cosmic background radiation) is 2.7 Kelvin (note the lack of a "degree" sign), yes? And it is dropping geometrically? So, when the universe was half as old, the temperature was 5.4 Kelvin? When it was a quarter of its current age, the temperature was 10.8 K, and so on.

So a temperature of 105 K would mean seeing light from a time when the universe was only about 2% of its present age, correct?

Regards,

That's a clever analysis; I don't know enough cosmology to be able to say whether it's true as to reasoning, but your result is pretty accurate. I think they expect JWST to see back to something like 2 or 3% of way back to the Big Bang, although I don't think they're exactly certain of "how far back" they will see.

It seems to me like there's some assumptions you're making in your essentially linear approximation of peak black-body radiation intensity over time that I'm not knowledgeable enough to be able to judge as to validity, but your reasoning don't seem obviously wrong.

Also the resolving power in terms of dynamic range of JWST's image sensors is another issue; it seems to me that that would have a bearing on your theory. I'm not sure that a distant object just a few degrees above the 105°K temperature limit would stand out from the background enough for the JWST sensors to get much of a read on it. I suppose if they integrate light for many weeks or months (like they did for the Hubble Deep Field pictures) they could get enough signal-to-noise ratio to resolve such an object.