On the contrary. Take a punch-card, stick it in your 029 keypunch, and add 80 bytes of information to it by typing away. Now it weighs less than when you started. Information has negative mass.
It has been said that a punched-card is the least-efficient form of data storage ever invented. The data is stored in the form of holes in the card. The card's only purpose therefore is to hold the holes in place, so it is 100% redundant.
Showing that X implies a contradiction is showing not X in intuitionistic/constructive logic, yes.
However, you can’t show X by assuming not X and reaching a contradiction. By doing so you would only show not(not(X))