But we still can't be sure it isn't some sort of natural phenomenon.

No known conditions in space would support it as a natural phenomenon.

"No one has ever seen a problem like this, and it may very well turn out to be a natural phenomenon."

I don't know who did it, or why, but this is not a natural phenomenon.

Fire is one of the most useful natural phenomena in the world.

Death is a natural phenomenon and the dead must be buried.

How is it they make use of a natural phenomenon for their dirty work?

Far more likely, you had accidentally come across a natural phenomenon.

A force of nature is a natural phenomenon that humans cannot control.

A natural phenomenon, you might say - but you'd be wrong.

He saw the Earth as the product of natural forces.

He was a sort of natural force, like the wind.

This wasn't the result of any earthquake or natural force.

An ice age can be a result of a nuclear winter or natural forces.

He thought the Earth must have developed by slow, natural forces.

But who will govern the use of the power to control natural forces?

However, the impact of the state was felt through natural forces, and it varied over time.

It did not result from natural forces of the market or geography.

Changes in climate may be due to natural forces or from human activities.

From now on the first rule of engineering would be to work with Earth's natural forces, never against them.