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 you’re 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 you’re 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.
It’ll 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, it’ll 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, you’re 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 same – that’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 anything – from 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 it’ll 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 qubits’ output 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 it’ll 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, we’ll be able to take chances even on teleportation and
time machines.
What?
A person can dream!
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