The way a blender creates a deep vortex in the middle

Your blender is basically a high-speed kitchen disaster. When the blades kick off, they fling everything outward like spilled beer on a spinning record player. The liquid tries to fly through the wall, but the jar forces it into a frantic circle.

This outward push—inertia in its messiest form—leaves a hollow, low-pressure vortex in the center. Gravity hates an empty gap, so it shoves the top layer down into that hole, straight back into the blades.

It’s a chaotic loop of physics that ensures your smoothie has zero chunky surprises.

Hold on, why doesn't gravity just win and fill that hole back up?

Think of a mosh pit at a dive bar. Everyone is shoving outward so hard that there is a literal no-man's land in the middle. The faster the music—the blades—the harder they push against the walls.

Even though gravity tries to dump the top layer back in, the spin speed acts like a bodyguard. It keeps the liquid pinned against the glass like a wet sock in a spin cycle.

The hole stays open because that outward push is winning the tug-of-war. Slow the blender down, and the vortex collapses like a soufflé in a cold kitchen.

Wait, if it's pinned to the walls, why doesn't it just climb out?

Oh, it absolutely will. If you forget the lid, you’re essentially turning your kitchen into a Jackson Pollock painting made of kale and protein powder.

As the blades spin faster, that outward shove—inertia—gets more violent. Since the glass walls are blocking the exit, the liquid has nowhere to go but up, scaling the sides like a frantic rock climber escaping a flood.

It’s a race between the jar's height and the motor's speed. Crank it high enough, and the liquid wins, leaping over the rim and onto your clean shirt.

If the blades spin sideways, why does the mess go upwards?

Think of it like a crowded elevator where the doors are stuck. The blades are shoving everyone toward the walls. Once the floor space is totally packed, the new arrivals have to stand on people's shoulders just to fit.

Because the liquid is incompressible—it won't shrink or squash—it gets squeezed. Since the bottom of the jar is a dead end, that pressure forces the liquid to flee toward the only exit available: the open air at the top.

It’s basically a vertical traffic jam. The faster the spin, the more liquid is fighting for a spot on the wall, and the higher that smoothie pyramid climbs until it hits your ceiling.

What if the walls were slanted like a bowl instead of straight?

If you swap that jar for a flared bowl, you’ve basically built a launchpad for your soup. In a straight jar, the liquid has to fight gravity vertically. But with slanted walls, that outward shove acts like a skater hitting a half-pipe.

The slope gives the liquid a literal ramp to glide up. Instead of a vertical traffic jam, it’s a high-speed exit. This is why professional blenders have specific angles—to guide the chaos back down instead of letting it ramp into the stratosphere.

It’s the difference between hitting a brick wall and hitting a jump in Mario Kart. One stops you cold; the other sends you flying into the microwave.