He couldn't have copyrighted E=mc^2, he'd have had to patent it. But laws of nature are excluded from patent eligibiligy in the US, and presumably most other jurisdictions.
Software code is an interesting edge case in the middle. The code itself is a creative expression, and so copyright applies. This brings benefits as well as restrictions; software code is also speech as far as many free-speech rights are concerned. The algorithms expressed by the code are subject to software patents, which is a more controversial grey area.