can anyone tell me how planets form and how we know that life can only exist in an environment where there is liquid water. is it possible that we only know how to observe or measure lifeforms we have previously encountered?:confused:
im doing an experiment on ultrasonics. i have to find out where ther's a hole in a block of aluminium. what should i expect to see on the oscilloscope and how can i measure the size of the hole from my data? it says on another site there should be impedence i.e a disturbance but I am not really...