What if you could shrink to the size of an ant?

Look at an ant. It is so small!

What if you could shrink down to be as tiny as an ant? What would the world feel like?

A physics answer expects an ant to survive a fall from a skyscraper, and ants carry leaves and prey that look far too heavy for them. We could never do those things. Is an ant just a tiny copy of a big animal, or does being small change the rules?

This lab is a thought experiment. We can't really shrink, but we can use what scientists have measured about small things to imagine what we might notice.

Shrinking an object by a factor k multiplies its lengths by k, its areas by k² and its volume, and so its mass and weight, by k³. Forces that act on surfaces, such as air drag and surface tension, therefore become relatively far stronger as things get smaller.

This thought experiment shrinks a child to ant size and follows three consequences: how falls change, how water behaves and how strength compares with weight. Each consequence is labeled fact, model or idea.

We are big and heavy. When we jump off a step, we land with a bump.

Water feels like a liquid we can splash. Our muscles can lift our own body, but not much more.

At our size, gravity is the boss. Jump off a wall and you speed up the whole way down, because the air pushes back on you only a little. Water splashes and pours, and a drop is a tiny thing that runs off your hand.

And lifting something many times heavier than you? No chance.

For a human, weight is large compared with the air drag acting on the body, so a falling person keeps speeding up to a far higher speed than an ant before drag balances weight. The same scaling is why, as the University of Illinois answer notes, heavy skydivers fall appreciably faster than light ones.

Strength may follow a different rule. A common scaling argument says the force a muscle or joint can carry depends on its cross-sectional area, which scales as length squared, while the weight it must carry scales as length cubed. This lab treats that argument as an idea, not a measured law.

Now imagine you are as small as an ant.

You might float down gently when you fall. A water drop might look like a big, wobbly ball. And you might feel very strong for your size!

Shrink to ant size and the balance flips. Your weight becomes tiny, but the air still pushes on your skin, so a fall might feel like floating down gently. A water drop might be nearly as big as you, and its surface might act like a stretchy skin you might bounce on or get stuck in.

Your muscles might feel amazingly strong too, because your weight shrank much more than your strength. These are ideas, built from what scientists have measured about small creatures.

Shrink a 1.3 m child by a factor of about 300 in length and they would be about 4 mm tall, the length of a pavement ant worker (2.5 to 4 mm, Penn State Extension). Weight would fall about 300³ ≈ 27 million times, but area only 300² = 90,000 times. An answer on the University of Illinois physics Q&A estimates an ant's terminal speed in air at no more than about 2 m/s.

Surface tension, which USGS notes is higher for water than for any liquid except mercury, might then dominate how water behaves around you. The specific experiences in this lab are reasoned ideas, not measurements of a shrunken human.

Big things are heavy for their size. Tiny things are light for their size.

So air and water can push tiny things around much more.

Here is the secret. If you make something twice as big in every direction, its weight goes up eight times, but its skin only grows four times. An answer on a University of Illinois physics question site uses exactly this to explain falling: gravity grows with volume, but the push of the air grows with surface area.

Go the other way, to something tiny, and weight shrinks much faster than skin. That is why air matters so much more for a falling ant than for us, and the same reasoning suggests that water's surface and the strength of small bodies might matter more too.

The answer on the University of Illinois physics Q&A puts it directly: gravity scales with volume, as length cubed, while air resistance scales with surface area, as length squared, so doubling every dimension multiplies weight by 8 but drag by 4. The same kind of reasoning can be applied to surface tension, which acts along a surface, and to strength, which depends on cross-sections, though here it is a scaling idea rather than a measurement.

This is a scaling argument, not a precise model: real insects also differ from us in shape, materials and body plan, so shrinking a human would not simply produce an ant.

A physics answer says an ant could fall from very high up and be fine. Water striders walk on top of ponds!

Scientists tested how strong an ant's neck is. It was much stronger than they guessed.

Real small creatures show these rules every day. Water striders walk on ponds using water's surface tension and their long, water-repelling legs, the U.S. Geological Survey explains.

In 2014, engineers at Ohio State University tested the neck joint of a common field ant, the Allegheny mound ant. It could withstand forces up to 5,000 times the ant's own weight. The lead engineer, Carlos Castro, said they had expected about 1,000 times.

USGS describes water striders using water's high surface tension and long, slender, hydrophobic legs that spread their weight. Ohio State engineers, reporting in the Journal of Biomechanics in February 2014, found that the neck joint of the Allegheny mound ant (Formica exsectoides) withstands forces up to 5,000 times the ant's weight; Carlos Castro said their conservative estimate had been 1,000 times.

The team studied the joint's structure with electron microscopy and micro-CT, hoping similar joints might help future robots. The University of Illinois answer adds that ants have very hard exoskeletons and expects an ant to survive even a fall from the Empire State Building.