The Red Sea dam is a speculative macro-engineering proposal put forward in 2007 by a group of scientists and engineers.

The diametric drive was a speculative proposal for an "engine" which would create a non-conservative gravitational field with non-zero curl.

The differential sail was another speculative proposal, which appealed to the zero-point energy field.

Various other speculative proposals have been made, all of them failing to gain wide acceptance because no significant proof of the proposed connections has been found.

And I think it would now be most unlikely for a speculative proposal that hadn't come through a planning system to succeed.

And it wouldn't, you would never know for certain until a speculative proposal was actually put to the test.

This speculative proposal is based upon the shared yellow underparts and their living in the same general region.

Alternative speculative proposals at the time included square spiral interlacing and using Peano curves, but these were rejected as over-complicated.

Microsoft calls the government plan a "draconian" and "speculative" proposal that would bring "uncertainty and chaos."

Some scholars have advanced speculative proposals regarding the origin and meaning of the word Funan.