I'm no expert mathematician, but I believe Don said he wanted an answer in "one or two sentences", and nobody has provided anything less than a paragraph related to the subject.

Being a high school student that has not taken physics yet, this question is very interesting, and I would also appreciate a short and concise answer, instead of having to read 4 long paragraphs.

In conclusion, I would very much be interested in a short answer as to WHY it isn't possible to go faster than the speed of light.

Thanks!

"In order for knowledge to be understandable, it must be accessible. We live in a world today where people don't want to read long books to learn things. Bring the knowledge to the people, and they will learn it". - Sal Khan, Khan Academy