Okay, I better answer this since I wrote the quiz (it was a while ago, though).
1) E=mc^2 does not *prohibit* time travel, and that was the point here. I have lost my original sources for this quiz but I used a page similar to this:
http://www.iep.utm.edu/t/timetravel.htm
There are two sections on relativity (special and general) which cast some light on the issue.
The question was based on a recent discussion about tachyons (hypothetical particles moving faster than light) and was related to E=mc^2. Sorry about being so unclear...
2) The second one was taken from the book, "How to build a time machine" by Paul Davies. The question is simplified, and in fact the answer is partly correct (clocks either slow down or speed up depending on whether the plane moves eastward or westward - showing time dilation). Time dilation WAS at first proved using atomic clocks on airplanes, so maybe I just need to drop the second part of the option.
http://hyperphysics.phy-astr.gsu.edu...airtim.html#c3 -> details on the experiment.
The quizzes are always popularized because most people take them just for fun. If you find errors I would also appreciate suggestions for alternative answers. I'm not infallible, you know.
And...just for the record...the quiz has been taken more than 5,000 times and nobody has complained about it before. But I may still be wrong, of course.
Your Friendly Neighborhood Administrator
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