What is the source of electrons for PSI?

How can scientists test their ideas about the origin of the universe if they can't physically interact with or study?

Anurse is preparing to administer ampicillin 500 mg in 50 ml of dextrose 5% in water (d5w) to infuse over 15 min. the drop factor of the manual iv tubing is 10 gtt/ml. the nurse should set the manual iv infusion to deliver how many gtt/min? (round the answer to the nearest whole number. use a leading zero if it applies. do not use a trailing zero.)

What are some natural processes that represent physical and chemical changes?