A stadium wave around the equator

Lining the equator takes about 66 million people, and a wave moving at stadium speed would need about 39 days to go all the way around. That leaves about three weeks to get everyone in place, and the hard part is the ocean.

The challenge

Imagine aliens land and give us a challenge. We have to send a stadium wave, the kind where a crowd stands and raises its arms one section after another, all the way around the equator. We get two months. If we miss, they take over the planet.

It sounds silly, but it breaks into a few honest questions. How many people would it take? How fast does a wave move? And what do we do about the parts of the equator where nobody can stand?

How many people

The equator is 40,075 kilometers around, which is about 24,901 miles, or nearly 25,000. If people stand side by side, shoulder to shoulder, each one takes up about two feet. So the number of people you need is the length of the equator divided by two feet:

24,901 mi × 5,280 ft ÷ 2 ft ≈ 66 million people

With about 8.3 billion people on Earth, that's 0.79% of everyone, just under 1%. Finding enough people is not the problem.

How fast a wave travels

Physicists have actually studied stadium waves. In a 2002 paper in Nature, Illés Farkas, Dirk Helbing and Tamás Vicsek studied waves in large stadiums and found they move at about 12 meters per second, roughly 20 seats every second. That's about 39 feet per second, or about 40.

At that speed, one full lap of the equator takes:

40,075,017 m ÷ 12 m/s ≈ 3.3 million s ≈ 39 days

The deadline is two months, about 60 days. If the wave needs 39 of them, that leaves about 21 days, or three weeks, to get 66 million people into position. This assumes the wave keeps stadium pace the whole way, with nobody missing their turn for 39 days straight.

The ocean problem

Here is the hard part. Most of the equator is water. To measure how much, you can take a map of the world's coastlines, the Natural Earth land outlines, and check the equator every quarter of a degree of longitude: land or sea. About 79% of those points are ocean. The video rounds this down to 78%.

That works out to about 19,600 miles of ocean, nearly 20,000 miles where people can't simply stand. They would need to stand on boats, lined up end to end.

Start with the big ships. Using rough estimates of the world's fleet, here is how much ocean each kind of large ship could cover end to end:

Aircraft carriers: about 25 ships at about 260 meters each
Tankers: about 18,000 at about 180 meters
Bulk carriers: about 14,000 at about 190 meters
Container ships: about 6,500 at about 220 meters
Cruise ships: about 350 at about 250 meters
General cargo ships: about 18,000 at about 110 meters
Other large vessels: about 59,000 at about 65 meters

Multiply each count by its length and add them up, and the big ships stretch about 8,200 miles. Call it 8,000. That leaves about 11,300 miles of open water.

Filling the gap with fishing boats

Fishing boats are much smaller, but there are far more of them. Suppose you first use about 100,000 large fishing boats at around 30 meters each, then about 500,000 medium ones at around 15 meters. That covers roughly 6,500 miles. The last 4,800 miles or so get filled with small boats at about 8 meters each, which takes nearly a million more.

100,000 + 500,000 + ~970,000 ≈ 1.6 million fishing boats

Is that realistic? The Food and Agriculture Organization of the United Nations estimates there were about 4.9 million fishing vessels in the world in 2022. So the plan would need about a third of the world's fishing fleet, plus essentially every large ship afloat, parked in one line across the oceans.

The remaining fifth of the equator is land. There, people would be hiking through the Amazon rainforest and up into the Andes in Ecuador, where the equator line crosses high on the slopes of a volcano.

So, could we do it?

On paper, yes. The people exist, the wave is fast enough to finish with weeks to spare, and there are enough boats to bridge the oceans. The math isn't what makes it hard. The schedule is. Three weeks to move tens of millions of people and more than a million boats into a single line around the planet would be a logistics job on a scale nobody has ever tried. The numbers say it's possible. Whether we'd pull it off is another question.