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  • Through the years, people have collected a whole dictionary of phrases about wasting

  • time and how it can never be turned back.

  • It would be a shame to lose them all if some scientist were to prove that time is reversible.

  • Actually, it seems like that already happened!

  • Well kinda

  • Time travel might just be real.

  • No one could call you a slacker or a procrastinator.

  • Time is always on your side; you can beat the clock 10 times out of 10, and even unscramble

  • all the metaphorical eggs you want.

  • If youre a single quantum in highly improbable circumstances, simulated inside a quantum

  • computer, of course.

  • And even then, it probably wouldn’t be as simple as it sounds.

  • Did anybody understand what I just said?

  • Me neither.

  • Let’s continue, shall we?

  • A team of Russian scientists from the Moscow Institute of Physics and Technology stated

  • in a press release that they were able to reverse the state of quantum in time for a

  • minuscule fraction of time.

  • For this purpose, they used an IBM quantum computer and innumerable attempts, 85% of

  • which were successful in a simple system, and only 45% in a system that’s a bit more

  • complicated.

  • But simple isn’t exactly the right word here.

  • Nothing can be simple if youre talking about quantum computers and quantum physics

  • in general.

  • The easiest way to imagine what really happened during these experiments is to take a ball

  • and throw it at the wall.

  • Itll bounce right back into your hands.

  • Under the right circumstances, like the force you apply to the ball, and the angle at which

  • it strikes the wall, itll return to you while flying the same path at the same speed

  • as when it went to the wall in the first place.

  • Now let’s try another example.

  • This time, youre throwing a marble; it strikes the wall and breaks as expected, then

  • falls down.

  • But look, now it’s going back on the same trajectory, flies up, bounces off the wall,

  • and finally lands back in your hand while reassembling into one piece.

  • Did you notice the difference between those two examples?

  • In the first case, the ball returned to its default position without violating the natural

  • flow of time.

  • It just copied its own trajectory.

  • Even if you decide to watch it on rewind, nothing will visibly change here.

  • Looks convincing, but it has nothing to do with reversing time.

  • It’s just that circumstances allow the ball to return to its exact previous state and

  • position.

  • But the situation with the glass marble is much more interesting because if we put what

  • happened on rewind, we can clearly see how the marble changes its state, which can’t

  • be reversed in a linear flow of time from past to future.

  • Now it’s cracked, but a moment later it’s whole again.

  • Or a moment before?

  • How do you even explain it with words when time suddenly starts to go south like this?

  • Unfortunately, it’s not entirely clear from the publication of the Russian physicists

  • what their finding is closer to: a simple rewind that only visibly reverses time, or

  • the complete time reversal of a quantum.

  • Either way, it was supposed to be completely impossible to bring a quantum into its previous

  • state.

  • The concept of the arrow of time is an integral part of nature’s laws, like the laws of

  • thermodynamics for example.

  • The second law of thermodynamics dictates that every closed system, whether it consists

  • of just one elementary particle or of everything there is in the Universe, is constantly moving

  • towards disorder, and this process is both unstoppable and irreversible.

  • Basically, it means that time always goes in only one way: from past to future as everything

  • is constantly, irreversibly changing its state and condition.

  • Nothing ever stays the samethat’s a simple truth we all know, even without special

  • expertise in physics.

  • But the quantum world is kind of used to breaking all of our expectations at this point.

  • Quantum can be in two states simultaneously.

  • Quantum teleportation was proved to be real, and now it seems like even time itself isn’t

  • truly safe.

  • But among those miracles, the last one is particularly improbable, because it can only

  • happen in the simplest systems, and only in circumstances simulated in quantum computers.

  • A quantum computer is a real miracle of science, with vast processing power that comes with

  • one main difference from the classic computers: classic silicon-based computers use bits to

  • store information.

  • A bit is a basic unit of measurement that serves to contain data in a sequence of bits,

  • with each one giving only one of two possible outputs: 0 or 1.

  • Every single bit of memory is useless outside the sequence, but many bits combined can become

  • a code that could mean anythingfrom a singular digit to a picture of a cat.

  • Zeros in this sequence are bits that don’t get to be electrically charged, and ones are

  • those that are powered.

  • This is how memory works in your computer or smartphone.

  • Quantum computers use quantum bits or qubits instead of bits.

  • These are also the most basic units of information for a quantum computer.

  • The difference is that computers using qubits have much more potential processing power

  • than a classic computer.

  • When bits can only be in one of the two possible states, qubits use quantum particles, which

  • can be not only in one of two states, but also in both at the same time.

  • This can be explained by the fact that elemental particles like photons and electrons, which

  • are used in qubits, can be in a state known as a superposition.

  • It’s easy to represent as both 0 and 1, and anything in between.

  • This can give many more possible meanings to one qubit, so itll have more potential

  • for computing.

  • The only problem is that the superposition of particles is quite unstable and can be

  • disrupted even by looking at them and trying to read the output in any other direct way.

  • When disturbed, particles will immediately go from a superposition to one of the two

  • main states.

  • The difficulty of coming up with indirect methods of reading qubitsoutput led to

  • the slow growth of quantum computing.

  • More than half of the ideas related to it are still highly theoretical, and the most

  • complex quantum computer still has only 16 qubits.

  • For a time-reversal experiment, only two qubits were used, and even if it wasn’t true time-reversal,

  • it’s a giant breakthrough for quantum computing itself.

  • The result of these experiments shows that by applying a special equation to qubit particles,

  • they can effectively step back in their state like after a good sip from the Fountain of

  • Youth.

  • This may allow quantum computers to backtrack the progress of processing information.

  • This way itll be possible to better test quantum programs.

  • It’s basically an undo button for quantum processes!

  • Another borderline impossible feat of the quantum world is quantum teleportation.

  • A group of computer scientists was able to basically transport a particle through space

  • in an instant.

  • One moment it was there, and then it blinked in another place!

  • But once again, it’s not science fiction; not everything is what it seems at first glance.

  • To be fair, there were initially two particles linked to each other by a special kind of

  • relation in quantum physics called entanglement.

  • Then they were separated from one another and one of them was thoroughly scanned.

  • As we already know, scanning a particle applies stress on it, and therefore disrupts its state

  • almost completely.

  • Basically, after the scan, one of the particles became something completely different from

  • what was scanned.

  • Information about the properties of this particle was then sent to the second particle and it

  • inherited them all, effectively becoming the first particle.

  • I bet you can spot the problem here.

  • None of the particles were really transported anywhere, but the information about them was

  • teleported.

  • And in basic terms, teleportation means scanning and disrupting something in one place and

  • reassembling it in another with the use of information from the scan.

  • Therefore, what scientists saw there was still teleportation.

  • Quantum teleportation, just like quantum time-reversal, can’t be used on anything except particles,

  • like electrons and photons, so it’s actually too soon to get your hopes up for getting

  • to work in the blink of an eye, or to turn back time and wake up earlier to be on time.

  • But who knows what could be possible if all this new knowledge could be used to build

  • the first practical quantum computers.

  • With their processing powers, well be able to take chances even on teleportation and

  • time machines.

  • What?

  • A person can dream!

  • Hey, if you learned something new today, then give the video a like and share it with a

  • friend!

  • And here are some other cool videos I think you'll enjoy.

  • Just click to the left or right, and stay on the Bright Side of life!

Through the years, people have collected a whole dictionary of phrases about wasting

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科学者たちは時の矢を戻したかもしれない (Scientists May Have Turned Back the Arrow of Time)

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    林宜悉 に公開 2021 年 01 月 14 日
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