[Sloth]

I'm not committed one way or the other, but would it have been possible to make Buzz Aldrin and the (nowadays habitually silent) Neil Armstrong THINK they traveled to the Moon even if they didn't?

Uh, no. There is no technology that creates sustained low gravity on Earth.

[Analyzing Inconsistencies]

If the folks who knew how to make such a hypothetical technology let it become known, plenty of government bureaucrats and contractors would be out of billions that they still get for sending folks on the Space Shuttle. NASA's budget's over $15 billion annually. If human spaceflight ended, many think NASA's science budget would be substantially depleted because voters and taxpayers would care far less about space. So there does appear to be an economic incentive to keep certain technologies hush hush. Or maybe Neil's so quiet for a reason. In other countries, folks who can be blackmailed are allowed to get ahead because the blackmailing serves as their leash...

[Analyzing Inconsistencies]

I should add that "microgravity research" is still considered to be a major justification for sending humans into space despite how NASA does it nearly 30 times more expensively than the Russians do, and with a far less impressive safety record too. If zero gravity's obtainable here on Earth, you can imagine how certain vested interests would be substantially threatened.