Oil has always been extremely controversial. The "dark liquid" has been at the center of wars, economic upheavals and environmental disasters since the first modern wells began pumping petroleum from the Earth in the mid-1800s.

An oil embargo in 1973 almost ground America to a halt. In 2010, almost 5 million barrels of crude hemorrhaged into the Gulf of Mexico after an explosion on the Deepwater Horizon oil rig. Meanwhile, we soldier on through two devastating wars some believe were started over oil.

Now, a growing and vocal movement of people believe that the gusher of oil that fuels modern life has slown to a trickle - and they are prepared to make drastic changes to offset the looming danger. They are selling their cars, moving off the electric grid to live without power, planting vegetable patches, building chicken coops and stockpiling food, water, wood and, in some cases, weapons.

They believe in "peak oil," the theory that the world has -- or will very soon -- reach a high point of oil production before the supply eventually nosedives to nothing. With petroleum getting harder to reach, they believe oil companies are taking dangerous risks to tap what remains.

Others, though, maintain that "peak oil" is a myth. Who's right?

Peak Into The Past

Peak oil theory is based on the research of M. King Hubbert, a geoscientist who worked for the Shell Oil Company. In 1956, Hubbert predicted that the United State's oil production would go into decline in the early 1970s. Although harshly criticized by some oil experts and economists, Hubbert was proved right when the country's production declined in 1971.

According to Hubbert's peak theory, worldwide oil production is now at or near its apex. Economists, scientists and oil industry experts argue over the timeline, but apocalyptic survivalists, international energy analysts and at least two United States congressmen agree on one thing: there's trouble ahead if we aren't prepared.