Careful how you use physical laws, Naomi -- that Energy cannot be destroyed does not mean that it survives in the same form even for a second. Energy covers so many different phenomena and they are constantly changing from one to another and, ultimately, to heat.
Equally if memory and such is tied to its physical cradle of the brain then death would equate to the loss of all information stored in there. This is rather like what happens when computers fail and crash -- information contained within them is, to some extent at least, lost, because that information relied on the hardware to survive.
It's dangerous, or at least not worth spending too much time, speculating on the nature of the Soul after death when its very existence is pure conjecture.