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Okay, imagine you have a completely flat, circular track, kind of like a tiny Hot Wheels racetrack. You take a small, shiny metal disk that looks like a thick coin, and you place it about two inches above the track. You let go of the coin.
It doesn’t fall. It doesn’t drop to the floor. It just perfectly freezes in mid-air.
You can literally push the coin with your finger, and it will silently float around the track like a tiny flying saucer. If you grab the track and flip the entire thing completely upside down, the metal coin doesn’t fall. It just continues floating upside down, locked in the invisible air.
This is not a camera trick, and it is not a Hollywood special effect. It is a hardcore, mind-bending physics experiment called Quantum Levitation (or Quantum Locking). Let me explain exactly how extreme cold can turn a normal piece of metal into a gravity-defying UFO.
The Magic of Superconductors
To understand how things can float upside down, we have to talk about a very special type of metal called a Superconductor.
Normally, if you push electricity through a copper wire, the wire gets hot. It fights the electricity. That resistance slows the electricity down.
But a superconductor is basically the perfect highway. When it gets incredibly, unimaginably cold, it loses 100% of its resistance. Electricity can flow through it absolutely perfectly forever without ever losing a single drop of energy.
But getting that cold is really hard. We aren’t talking about putting it in your kitchen freezer. To make a superconductor work, you have to submerge it in Liquid Nitrogen, which is a terrifyingly cold -320°F (-196°C)!
If you want to read the incredibly complex quantum physics behind how electrical resistance totally disappears at sub-zero temperatures, the Institute of Physics (IOP) has the ultimate breakdown.
The Invisible Magnets
Okay, so we have a super cold, perfect piece of metal. Why does it float?
This is where magnets come in. The track the disk floats over is actually made of hundreds of incredibly strong magnets. Normally, a magnet shoots invisible magnetic lines (like invisible hairs) straight up into the air.
When you place a normal piece of metal over the track, the magnetic lines just pass right through the metal like ghosts, and the metal falls.
But a Superconductor hates magnetic lines. The second you place the freezing cold Superconductor over the magnets, it acts like a solid brick wall. It physically violently blocks all the magnetic lines, refusing to let them pass through.
Because the magnetic lines can’t go through the disk, they bend around it, totally wrapping the disk in an invisible, tight web of magnetic force. The disk gets completely trapped inside this invisible web. It is locked in the air!
You can learn all about how these invisible magnetic flux lines work over at the American Physical Society (APS).
Locked in Place
This is why it is technically called “Quantum Locking” instead of just levitating. The disk isn’t just floating on a cushion of air. It is literally pinned in exactly the same spot by the invisible magnetic web.
If you push the disk to the side, it moves smoothly around the track, but it refuses to move up or down. If you flip the whole track upside down, the invisible magnetic web holds the disk perfectly in the air underneath it!
Eventually, the Liquid Nitrogen boils away into the air. As the Superconductor slowly warms back up to room temperature, the magic wears off. The invisible web breaks, and the metal disk unceremoniously drops to the floor like a normal, boring piece of metal.
Because Liquid Nitrogen is cold enough to instantly give you severe frostbite, you can never, ever touch it without Cryogenic Safety Gloves and a heavy-duty Face Shield.
To read the incredibly strict safety protocols regarding how universities handle sub-zero cryogenic liquids, the Occupational Safety and Health Administration (OSHA) has the official rulebook.
Quick Quantum Summary
What you need:
– A specially made YBCO Superconductor disk
– A track built entirely out of strong Neodymium magnets
– A thermos filled with Liquid Nitrogen
– Cryogenic safety gear and plastic tongs
Step-by-step guide:
1. Put on your heavy-duty cryogenic gloves and face shield.
2. Use your plastic tongs to carefully place the Superconductor disk inside a styrofoam cup.
3. Slowly pour Liquid Nitrogen over the disk until it stops aggressively boiling. The disk is now -320°F!
4. Use the tongs to carefully lift the freezing disk out of the cup and place it about an inch above the magnetic track.
5. Let go of the tongs. The disk will perfectly float in mid-air!
6. Give the disk a gentle push and watch it silently fly around the track like a UFO!
10 Levitation Brain Teasers
Is your brain floating with new ideas? See if you can lock onto the answers to these 10 quantum riddles!
1. The Riddle: I am the fancy science term for a special metal that allows electricity to flow perfectly when I get freezing cold. What am I?
The Answer: A superconductor.
2. The Riddle: I am the terrifyingly cold, smoking liquid used to drop the temperature of the metal to -320°F. What am I?
The Answer: Liquid Nitrogen.
3. The Riddle: I am the invisible force field that shoots up from the track and gets violently blocked by the superconductor. What am I?
The Answer: Magnetic lines (or magnetism).
4. The Riddle: I am the exact, super heavy-duty protective gear you must wear on your hands so you don’t get instant frostbite. What am I?
The Answer: Cryogenic gloves.
5. The Riddle: I am the tiny, invisible particle of electricity that is finally allowed to run down the wire without any resistance. What am I?
The Answer: An electron.
6. The Riddle: I am the fancy scientific name for the “invisible web” that perfectly traps the disk in mid-air. What am I?
The Answer: Quantum Locking (or Flux Pinning).
7. The Riddle: If you flip the magnetic track completely upside down, what does the floating disk do?
The Answer: It stays floating upside down!
8. The Riddle: I am the basic force of the universe that this entire experiment completely defies and ignores. What am I?
The Answer: Gravity.
9. The Riddle: I am the tool you must use to pick up the freezing disk so you never have to actually touch it. What am I?
The Answer: Tongs.
10. The Riddle: When the disk slowly gets warm again, what happens to the magic trick?
The Answer: It stops working (the disk falls).
The Wrap Up
Quantum Levitation is easily one of the most unbelievable things you can ever witness with your own eyes. It looks like a video game glitch in real life.
By dropping the temperature to absolute extremes, we can fundamentally change how metal interacts with the universe. Scientists are actually trying to build real, massive bullet trains that use this exact technology to silently float over the tracks at 300 mph! If you want to dive deeper into how quantum physics is building the future, bookmark the National Science Foundation (NSF). The future is floating!
Cited Sources & Evidence
- Institute of Physics (IOP)
- American Physical Society (APS)
- Occupational Safety and Health Administration (OSHA)
- National Science Foundation (NSF)