Basic answer is yes it can. The original superconductor was mercury, which had to be distilled before it could be pure enough to go superconductive.

This is covered in this very informative discussion from BBC radio.

I hope this is available in your area. This series is great for curious people wanting to learn about many subjects.

No, just left and right. Believe me, I just retired from working 35 years in the HiFi (turntable manufacturing) business. But - in most music recorded by microphone, bass is pretty much mono. The wavelength is so long that the signal picked up by the left and right microphones will be almost identical. That’s why you can put a subwoofer almost anywhere in a room and it won’t make much difference.

If the left and right channels were cut IN PHASE then this common movement would translate to a pure vertical movement of the stylus. This is bad news, as it can make the stylus lose contact with the record surface. So one channel is phase reversed (180 degrees) so that the common signal then translates to HORIZONTAL movement. Only the difference between L & R makes the stylus move up and down.

Note: I had previously forgotten this phase reversal detail, but it came back to me, and so I have now edited this post to correct the above paragraph. This other Reddit post on the subject is very informative!

It is of course possible for an engineer to put a full bass track on one channel, but there’s no real sense in doing that. If they want to make it seem like the bass player is standing on one side, they only need to put the mid and high frequency harmonics over there but the low frequency stuff should be mono, so you don’t overload the bass drivers or amps on one channel, and run the risk of hitting the end stops on bass drivers at high volume, which sounds bad and can damage the speakers.