We've flipped the switch. The lights go on. Globally, we do this without thinking. Hundreds of billions of times every single day. You hear the words power grid often in the news, but if you really understand what it is exactly. It's so big that you can't see it in its entirety. When you travel by car from city to city, many times you see a small piece of it.

Those large towers supporting three huge cables are a part of it.

Their job is to transfer massive amounts of power from the thousands of power-generating plants across America to populated areas.

And those same lines transfer power from areas that have surplus

to areas that need more than their power plants can generate at a given moment. Imagine Florida

in the winter. It often has an abundance of power generating capabilities, and it helps New York

and New England with the extra power it needs for heating.

The same is true in the summer in the southwestern United States.

When Arizona and Southern California need air conditioning, the northwest, Seattle and Portland,

often have extra power to sell.

So the power grid is an incredibly complex network of power plants and transmission lines all locked together in perfect synchronization to bring low-cost electrical power to every area

of the nation.

But the very thing that makes the grid strong, its ability to transfer massive amounts of

power when it's needed, is also the root cause of its weakness. When a large area loses power,

the grid automatically begins transferring power from another area. But as the blackout area is

very large, the area that's being called on for extra power may quickly overload. It then calls on yet

another area for power. And that can overload. It then calls on yet another area for power, and that

can overload, and then a deadly domino effect begins. Region after region becomes overloaded,

causing power plant of a power plant to literally kick offline to protect itself from becoming

damage. As the grid begins falling, the cascade effect speeds rapidly.

Once a large area is blacked out, bringing it back up is no easy task.

Power crews simply can't go to a breaker box and reset the breaker.

...