How to know if a business idea / product is possible?

I was thinking about business ideas and realized that in order for a new innovative technology to really supply needs in this time it has to be great. This is what led me in to thinking what do I do if I have random products or idea that I don't know if it is good or not and before I do anything else I want to test them so I can see if they could even exist.

For Example:
Elon Musk was talking in an interview about neural ink and was getting asked about some futuristic type...

How to know if a business idea / product is possible?

from How to know if a business idea / product is possible?