Answer:
What is it that given one, you’ll have either two or none?
Until I am measured I am not known, Yet how you miss me when I have flown.
A hole in a pole, though I fill a hole in white. I'm used more by the day, and less by the night.
It's been around for millions of years, but is never more than a month old. What is it?
In your fire you hear me scream, creaking and whining, yet I am dead before you lay me in your hearth.
All about, but cannot be seen, Can be captured, cannot be held, No throat, but can be heard. Who am I?