These people believe in the Technological Singularity theory: The possibility that technologically augmented intelligence will change human life as we know it or possibly wipe it out completely.

CNN: Apocalypse believers' big finish predictions vary

One possibility is that the amyloid theory is right, but that the Eli Lilly drug is flawed and did not hit the proper molecular target, and ended up merely causing toxicity.

FORBES: Eli Lilly Alzheimer's Disease Failure Bolsters Amyloid Theory Skeptics

The deal, in theory, avoids the possibility of a imminent default on US payment obligations and lets Republicans off the hook.

FORBES: On Washington, Investor Confidence At Zero

After hearing the theory, they shrugged and said they had already thought of that possibility a long time ago.

CNN: ASIANOW - TIME Asia | Young China | 'Is There Anything Wrong with Love?'

And another is the possibility of home-school athletes having an unfair advantage because they could, in theory, tailor their school day around their training schedule.

FORBES: Tim Tebow: A better quarterback than a law

Rather than abandon the theory, scientists fell back on the notion that the data jibed with the possibility that rising carbon dioxide levels were reinforcing the warming trend in what's called a positive feedback loop.

WSJ: Matt Ridley on Confirmation Bias and Global Warming | Mind & Matter

In spite of these misgivings, there is nothing in Einstein's theory of space, time and gravitation to forbid journeying into the past, a possibility that Einstein himself hated.

CNN: Time travel: Can it really be done?