The Science Behind Godzilla

What is Godzilla?

Godzilla's exact species was not revealed in the original Japanese movie, Gojira. However, we do know that the ginormous creature is a product of significant amounts of radiation. It is safe to assume that Godzilla is a enlarged prehistoric dinosaur, potentially a Tyrannosaurus. According to my internet research the original Godzilla was 50 meters (164 ft) tall. National Geographic states that fossil evidence shows that the average Tyrannosaurus was about 4.6 to 6 meters (15 to 20 ft) tall. Let's assume Godzilla was 5 meters tall before it was exposed to radiation.

How could Godzilla have gotten so large?

There are only two plausible ways to supersize a T-rex. One way is to expand the space between and inside of the creature's molecules. If Godzilla was only 5 meters tall before the radiation and grew to be 50 meters tall, he must've been scaled up by a factor of 10. If so, Godzilla's volume increased by a factor of 1,000 (10^3). According to the law conservation of mass, the creature's mass would remain constant. Therefore Godzilla's density would lessen by a factor of 1,000, because mass is the product of volume times density. Godzilla, newly 1/1,000 times as dense as it used to be, would change into a gas. Godzilla's molecules would not be able to stay together.
The other way to supersize Godzilla would be to keep its density constant, but add 999 molecules for every 1 molecule it now contains. This would be pretty difficult considering the molecules would have to miraculously find their appropriate positions. By increasing the number of Godzilla's molecules its weight would increase by a factor of 1,000 (10^2), while the weight its bones could support would only increase by a factor of 100 (10^2). Godzilla's legs would have to be 10 times stronger to be able to support his weight. In reality, almost all of Godzilla's joints and bones would not be able to function properly and Godzilla would be an immobile pile of scales.