Physics. It involves mathematics and esoteric-looking equations to memorize, which is paradise to some but one level of hell for others. Writers often play fast and loose with physics - sometimes intentionally, sometimes not. This is usually acceptable when it makes for good storytelling and/or just plain awesomeness, and one should always keep the MST3K Mantra in mind. However, an Egregious violation of the laws of physics can result in loss of Willing Suspension of Disbelief, especially in a story that tries to be taken seriously, or if the error could have been avoided with minimal revision.