Time Travel Requires a Time Machine. Literally.

Time travel is possible, maybe, but it's so far off and requires such massive gravitational fields that 1. nobody will live long enough to realize it and 2. the gravitational fields would likely destroy the Earth. Huh.

I don't understand a word of the article, since scientists and people who dumb-down science for mass consumption share the unfortunate inability to choose appropriate examples and metaphors ("string theory," anyone?), but I think it's quite funny that you couldn't travel any further back in time than the moment the time machine is created. So, this machine would represent the limit, literally, of agency.