There is measurable plausibility that we have 21 gram souls, which when they leave our bodies, enter into a timeless world, where they somehow fall into a black hole and suffer a lot.
Coragyps already beat me to snopes. Note that only the first patient he weighed at death lost approximately three quarters of an ounce (21.3g). The rest displayed results rather inconsistently -- some losing less but more over time, some losing and then gaining weight, etc...
Stephen ben Yeshua writes:
Donald Carpenter has published an e-book on the matter of the soul's weight, and he seems to be most trustworthy authority on that subject.
Can you supply a reference? A quick Google search doesn't return any results that would support your statement.