Johnson Noise in a conductor is very small: between 10-9 to 10^−12 V
How to measure it using an oscilloscope and amplifier? If it were a resistor that would be easy, but conductors have much smaller voltages.
To start with: what is the smallest voltage an oscilliscope can mesure?
"Very small signal allows you to adjust the front end gain But can sometimes be overwhelmed by the inherent noise of the oscilloscope" - source: http://www.rohde-schwarz-usa.com/rs/rohdeschwarz/images/20150310-HD-Webinar-Presentation.pdf Measuring Low Voltage Signals Using an Oscilloscope March 10, 2015 Richard Markley Oscilloscope Product Manager