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Let’s say that I had some device capable of outputting insane amounts of radiation, across the entire EM spectrum. If I wanted to affect the CMB to the point that, were Earth-based scientists to know that the device existed, they would be unable to gather any useful data from the CMB regarding the early universe, how much radiation would this theoretical device have to output? Peaking in what frequency? Where would be the optimal place to put it? Or multiple copies of it?

If someone who actually knows stuff about the CMB is scratching their head thinking I’m nuts, I probably am. I don’t know much about the CMB, except that it’s random EM waves that are leftovers from the Big Bang, peaking in the microwave frequency range. So if what I’m describing is absolutely implausible across all frequencies and amplitudes, I would appreciate if you could explain why, given my low level of knowledge on the topic.

In the event that for certain waves what I’m describing is possible, I would be curious to know if there’s actually anything in the known universe that could do it.

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    $\begingroup$ If you want help in your evil plot of ruining the work of astronomers, maybe a site for astronomy enthusiasts isn't the best place to seek advice ;) $\endgroup$
    – pela
    Oct 14 '18 at 9:48
  • $\begingroup$ Btw, the CMB is radio white noise in a 2.7K thermal spectrum. To destroy their measurements, you need to use high-power radio emitters around in the frequency. $\endgroup$
    – peterh
    Oct 14 '18 at 21:20
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It is not very clear what you mean. There are many cosmic sources of microwave radiation that emit so much energy and/or are so close to us that they confuse measurements of the cosmic microwave background. For example "compact sources" such as giant molecular clouds, supernova remnants, H II regions; "diffuse" sources due to dust in the galaxy and in our solar system. In order to get a clean signal, these foreground sources have to be removed from the data. There are also more subtle cosmological effects caused by lensing and gravitational time dilation caused by the large scale structure in the universe.

There are many ways and techniques that are used to characterise and remove these backgrounds (e.g. see Ade et al. 2013).

The most confusing background source would be one that is diffuse, spread over the whole sky almost uniformly and with a spectrum that is very similar to the cosmic microwave background. The source that most closely matches these properties is dust in our own solar system. An imperfect subtraction of this may have led to controversy over possible large scale anisotropies in the CMB- for example see Schwarz et al. (2015); who discuss the problems of removing the signatures of solar system dust.

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The CMB is basically the cooling of the high energy radiation of the early universe to achieve a nearly uniform dispersion of microwave shifted energy. It came to be via the decoupling, an early universe expansion-related event (~380,000 years after the big bang) that allowed particles to fall out of thermal equilibrium for the first time. This decoupling phase allowed hydrogen to form for the first time, and photons to roam free; the photons being what you're seeing cooled to the microwave spectrum in CMB pictures. Basically, the CMB is a snapshot of the first time photons could move freely.

Now, to effect the CMB as we see it you'd have to have something major happen at the same time the photons first escaped their "confinement," altering the energy/mass of the universe right before that, or changing one of its already intrinsic properties at the time. Nobody can do that as matter (and therefore a machine or an intelligence to use it) couldn't exist at that time, so let's call that impossible.

Otherwise, though nearly impossible and entirely improbable, you'd need something along the lines of another big bang event to occur inside our already formed universe, pouring enough energy/mass into the universe to both destroy what's there and cause another event where photons were confined and then let loose - making an entirely new CMB image.

Basically, it's not possible without destroying the universe and then allowing the universe to reform; so both the machine and the intelligence using it would be destroyed along with it.

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