No steady state Direct Current?

DC electric no steady state flatIf you take the scale to extremes for steady state DC (Direct Current) would you always see a relative change, an increase or decrease of voltage or current?

Some form of pulsating, variable, sine wave, step, high and low, 1 and 0?

With a large enough or long enough graph would you never have a true steady DC signal?

If your experimental results are sampled at the lowest or highest (least curved) part of the currents wave then it may not be as steady a state Direct Current as it would seem to indicate.

Could flat DC be classed as amazingly low frequency waves, step or variable Direct Currents?

What solar system, galaxy or universe size frequency could space plasma create for natural electricity currents in an electromagnetic universe?