First Time Travel Experiment Succeeded

Every day, our planet is bathed in sunlight. We routinely turn light sources on and off without thinking much of it. But imagine if one day you casually turned the lights off, fell asleep, and awoke in a completely different era - how might that happen? It has to do with light and quantum physics. Classical physics views the world linearly, like a movie playing from start to finish. But the quantum realm allows us to manipulate the scenes we're observing in fascinating and mysterious ways.

Take a normal light switch that can be either on or off - like a binary bit in a regular computer. But in quantum computers, there are qubits which can exist in multiple states simultaneously - both on and off at the same time. Strange yet true in our universe! This property called superposition enabled an incredible recent achievement - reversing time, at least in a tiny quantum computer experiment.

In autumn 2022, scientists from Oxford and Vienna used a quantum computer to create a program that reversed time. They took a tiny electron and made it go backward for a fraction of a second, like running a billiard ball break in reverse. Don't get too excited about time travel though! We can't recreate this in real life. The math shows that observing trillions of electrons for the age of the universe would likely yield just one time reversal, for an electron, by a fraction of a second. So no time machines yet. Just a quantum simulation.

There are limitations too. The larger the simulation, the more complex and inaccurate it becomes. With just 1 qubit, they succeeded. With 2, time reversal worked 85% of the time. With 3, just 50%. More qubits meant more errors. Success also depends on how much information is stored - teleporting a human seems impossible given our complexity. So for now, no time travel. But uses like error correction in quantum computing seem feasible. Tiny steps toward more discoveries!

For example, scientists recently sent light itself back in time. Light has incredible, barely grasped powers. Ancient Greeks thought vision involved emitted beams, disproved centuries later when Newton split white light into colors with a prism. Later we learned light is a wave. Even later, that it's both particle and wave - a paradox. The more we learn, the more mysteries emerge.

In 2016, scientists froze light briefly by trapping photons in ultracold atomic clouds. Then they went further - reversing the photon's direction in time with a special crystal. It moved into past and future simultaneously! This involved two quantum principles: superposition, and symmetry (flipping particles doesn't change laws). Together they defied time's forward march. But just for specific particles, not people yet. And huge energy would be needed to rewind even a second for a person. Still, reversing light is amazing.

Applications are emerging. Harvard researchers proposed hitching spaceships to supernova bursts to reach light speed. Usually, interstellar travel requires insane energy. But natural hypervelocity stars and meteors from supernovas could provide it - like ships catching wind. Advanced civilizations could harness these energy boosts to propel spacecraft with light or magnetic sails. Imagine solar sail ships riding supernova shockwaves, no engines required. A prototype laser sail has already reached 20% light speed! The dream is reaching Alpha Centauri in just 20 years.

Light continues to amaze, enabling inventions like real invisibility cloaks. A Canadian camouflage company created a cloak that needs no power, is paper-thin, affordable, and hides visible and infrared light. "Quantum stealth" bends light with lenticular lenses - corrugated sheets that refract light to conceal objects behind them. Not true invisibility yet, but objects become blurry or translucent. Maybe full effects will come in time. For now, enjoy floating heads and curiosity! Progress continues, perhaps one day even reversing time across scales. But for now, these glimpses into light's powers astound.