I did some undergrad research on the [ADMX][1] experiment, which is searching for a theoretical particle by listening for its interaction with a microwave photon in a big, ultra-cold cylinder that can be tuned to different frequencies.

A while back, they thought that they might have found something at 700 MHz. Then went looking again and it was gone. My professor said that it was probably a CPU in the lab.

[1]: https://en.wikipedia.org/wiki/Axion_Dark_Matter_Experiment