Your sweater is just a spaghetti-like tangle of fuzzy ropes separated by huge air gaps.
Dear Matthew Alice: When a sweater shrinks, where does the extra stuff go? If a large sweater shrinks in the washer to a small size, does it weigh the same later? Is the small sweater thicker now? Or do the fibers break off and go down the drain when the yams shorten? — Donna, Linda Vista
I have visions of elves sloshing around in your Maytag, cutting off the excess fabric and restitching your sweater four sizes smaller.... Curious concept. Your sweater is just a spaghetti-like tangle of fuzzy ropes separated by huge air gaps. The only thing lost in the shrinkage is empty space. Hot water makes the fibers contract, so your now-useless pullover is stiffer and denser than before, but will still weigh the same when you donate it to Goodwill.