About Quantum Theory And Facts

Lying just beneath everyday reality is a breathtaking world where much of what we perceive about the universe
Is wrong?
Physicist and best-selling author Brian Greene takes you on a journey that bends the rules of human experience
Why don’t we ever see events unfold in reverse orders according to the laws of physics?
this can happen
It’s a word that comes to light as we probe the most extreme realms of the cosmos from black holes
To the Big Bang to the very heart of matter itself
I’m gonna have what he said here our universe may be one of numerous parallel realities the
Three-dimensional world may be just an illusion and there’s no distinction between past
present and future
But how could this be how could we be so wrong about something so familiar does it bother us?
Absolutely, there’s no principle built into the laws of nature that say that theoretical physicists have to be happy
It’s a game-changing perspective that opens up a new world of possibilities
Coming on the realm of tiny atoms and particles the quantum realm
The laws here seem impossible
There’s a sense in which things don’t like to be tied down to just one location yet
They’re vital to everything in the universe. There’s no disagreement between quantum Kanaks, and any experiment. That’s ever been done
What do they reveal about the nature of reality?
Take a quantum leap on the fabric of the cosmos right now on, Nova
Major funding for Nova is provided by the following
David H Koch and
Discovering new novels
HH mi
And by the Corporation for Public Broadcasting and by
Contributions to your PBS station from viewers like you
Thank you
Major funding for the fabric of the cosmos is provided by the National Science Foundation where discoveries begin
And
The Alfred P sloan Foundation
supporting original research and public understanding of science
technology engineering
and mathematics
Additional funding is provided by the Arthur vining Davis foundations
dedicated to strengthening America’s future through education the
US Department of Energy’s Office of Science
and the George D Smith Fund
For thousands of years we’ve been trying to unlock the mysteries of how the universe works and
We’ve done pretty well
Coming up with a set of laws that describes the clear and certain motion of galaxies and stars and planets
But now we know at a fundamental level things are a lot more fuzzy
because we’ve discovered a
Revolutionary new set of laws that have completely transformed our picture of the universe
From outer space to the heart of New York City to the microscopic realm our view of the world has shifted
Thanks to the strange and mysterious laws. That are redefining our understanding reality
They’re the laws of quantum mechanics
Quantum mechanics rules over every atom and tiny particle in every piece of matter in
Stars and planets in rocks and buildings and in you and me
We don’t notice the strangeness of quantum mechanics in everyday life, but it’s always there if you know where to look
You just have to change your perspective and get down to the tiniest of scales
To the level of atoms and the particles inside them
Down at the quantum level the laws that govern this tiny realm
appear completely different from the familiar laws that govern big everyday objects and
Once you catch a glimpse of them you never look at the world in quite the same way
It’s almost impossible to picture how weird things can get down to the smallest of scales
But what if you could visit a place like this
Where the quantum laws were obvious where people and objects behave like tiny atoms and particles?
You’d be in for quite a show
Here objects do things that seem crazy I
Mean in the quantum world
There’s a sense in which things don’t like to be tied down to just one location
Or to follow just one path
It’s almost as if things were in more than one place at a time
And
What I do here can have an immediate effect somewhere else
Even if there’s no one there
And here’s one of the strangest things of all
If people behave like the particles inside the atom then most of the time you wouldn’t know exactly where they were
Instead they could be almost anywhere until you look for them hey, I’m gonna have what he’s having
So why do we believe these bizarre laws well for over 75 years
We’ve been using them to make predictions for how atoms and particles should behave and in experiment after
Experiment the quantum laws have always been right
It’s the best theory we have there are literally billions of pieces of confirming evidence for quantum mechanics
It has passed so many tests
Or so many bizarre predictions. There’s no disagreement between quantum Kanaks in any experiment. That’s ever been done
The quantum laws become most obvious when you get down to tiny scales like atoms but consider this
I’m made of atoms so are you so is everything else we see in the world around us
So it must be the case that these weird quantum laws are not just telling us about small things. They’re telling us
about reality
So how did we discover them?
The strange laws that seem to contradict much of what we thought we knew about the universe
Not long ago. We thought we had it pretty much figured out
The rules that govern how planets orbit the Sun?
How a ball arcs through the sky
How ripples move across the surface of a pond
These laws were all spelled out in a series of equations call classical mechanics
And they allowed us to predict the behavior of things with certainty
It all seemed to be making perfect sense
Until about a hundred years ago when scientists are struggling to explain some unusual properties of light
In particular the kind of light that glowed from gases when they were heated in a glass tube
When scientists observed this light through a prism they saw something. They’d never
expected
If you heated up some gas and looked at it through a prism it formed lines
Not the continuous spectrum that you see you’ve projected by piece of cut glass on your table
But very distinct lines
It wouldn’t give out a smear kind of complete rainbow of life
it would give out a sort of pencil beams of light at very specific colors and
It was something of a mystery how to understand. What was going on
An explanation for mysterious lines of color would come from a band of radical scientists
who at the beginning of the 20th century were grappling with the fundamental nature of the physical world and
Some of the most startling insights came from the mind of Niels Bohr a physicist who loved to discuss new ideas
over pingpong
Bohr was convinced that the solution to the mystery lay at the heart of matter in the structure of the atom
He thought that atoms resembled tiny solar systems with even tinier particles called electrons
Orbiting around a nucleus
Much the way the planets orbit around the Sun
But or proposed that unlike the solar system electrons could not move in just any orbit
Instead only certain orbits were allowed
And he had a really surprising and completely counter physical idea which was that there were definite States
fixed orbits that these electrons could have and
Only those orbits
Bohr said that when an atom was heated its electrons would become agitated and leaped from one fixed orbit to another
Each downward leap would emit energy in the form of light in very specific wavelengths
And that’s why atoms produce very specific colors. This is where we get the phrase
quantum leap
If it weren’t for the quantum leap you would have this
Smear of color coming out from an atom as it got excited or D excited
But that’s not what we see in the laboratory you see very sharp red very sharp greens. It’s the quantum leap
That’s the origin and the author of that sharp color
What made the quantum leap so surprising is that the electron goes directly from here to there
Seemingly without moving through the space in between
It was as if Mars suddenly pop from its own orbit out to Jupiter
Bohr argued that the quantum leap arises from a fundamental and
Fundamentally weird property of electrons and atoms that their energy comes in discrete chunks that cannot be subdivided
Specific minimum quantities called quanta and
That’s why there were only discrete specific orbits that electrons can occupy
An electrons had to be here or there and simply nowhere in between and that’s that’s like nothing we experience in everyday life
Think of your daily life
When you eat food you think your food is quantized
Do you think that you have to take a certain amount of minimum food food is not quantized?
But the energy of electrons in an atom I confessed that
Is very mysterious why that is
As mysterious as it might be for tiny particles in an atom to act this way
The evidence quickly mounted showing that or was right in more and more
Experiments electrons followed a different set of rules than planets or ping-pong balls
BorĂ¥s discovery was a game changer
And with this new picture of the atom Bohr and his colleagues found themselves on a collision course with the accepted laws of physics
The quantum leap was just the beginning
Soon Bohr’s radical views would bring him head-to-head with one of the greatest physicists in history
Albert Einstein was not afraid of new ideas
but during the 1920s the world of quantum mechanics began to veer in a direction Einstein did not want to go a
Direction that sharply diverged from the absolute definitive predictions that were the hallmark of classical physics
If you asked I in Stein or other physicists at the time what it was that this distinguished physics from all kind of flaky
speculation they would have said it’s not that we can predict things with certainty and
Quantum mechanics seemed to pull the rug out from under that
One test in particular which would come to be known as the double slit experiment
Exposed quantum mysteries like no other
If you’re looking for a description of reality based on certainty your expectations would be shattered
We can get a pretty good feel for the double-slit experiments
And how dramatically it alters our picture of reality by carry out a similar experiment not on the scale of tiny particles
But on the scale of more ordinary objects like those you find here in a bowling alley
But first I need to make a couple of adjustments to the lane
You’d expect that if I roll a few of these balls down the lane well either be
Stopped by the barrier or pass through one or the other slit, and hit the screen at the back
And in fact, that’s just what happens
Those balls that make it through always hit the screen directly behind
I’d to the left slit or the right slit
The double slit experiment was much like this except instead of bowling balls
You use electrons which are billions of times smaller
You can picture them like this
Let’s see what happens if I throw a bunch of these balls
When electrons are hurled at the two slits something very different happens on the other side
Instead of hitting just two areas the electrons land all over the detector screen creating a pattern of stripes
Including some right between the two slits the very place you think would be blocked
So what’s going on?
Well two physicists even in the 1920s this pattern could mean only one thing
Waves
Waves do all kinds of interesting things
Things that bowling balls would never do
They can split they can combine
If I sent a wave of water through the double slits it would split in two and then the two sets of waves would intersect
their peaks and valleys would combine
Getting bigger in some places
Smaller in others and sometimes they cancel each other out
With the height of the water corresponding to brightness on the screen
The peaks and valleys would create a series of stripes and what’s known as an interference pattern
So how could electrons which are particles form that pattern
How could a single electron end up in places a wave would go?
particles of particles waves are waves
How can a particle be a wave?
Unless you give up the idea that it’s a particle and think aha this thing that I thought was a particle was actually a wave
Wave in an ocean. That’s not a particle
The ocean is made out of particles, but the waves in the ocean of my particles
And rocks are not waves
rocks are rocks
So a rock is an example of a particle an ocean wave is an example of an ocean wave
and now
Somebody’s telling you a rock is like an ocean wave
What?
Back in the 1920s when a version of this experiment was first done scientists struggled to understand this wavy behavior
Some wondered of a single electron while in motion might spread out into a wave and
The physicist Erwin Schrodinger came up with an equation that seemed to describe it
Schrodinger thought that this wave was a description of an extended
Electron that somehow an electron got smeared out, and it was no longer a point but was like a mush
There was a lot of argument about exactly what this represented
Finally a physicist named Max Born came up with a new and revolutionary idea for what the wave equation described
Born said the wave is not a smeared out electron or anything else previously encountered in science
Instead he declared. It’s something that’s really peculiar a probability wave
That is born argue that the size of the way that any location predicts the likelihood
of the electron being found there
Where the wave is big that’s not where most of the electron is that’s where the electron is most likely to be and that’s just
Very strange right so the electron on its own seems to be a jumble of possibilities
You’re not allowed to ask, where is the electron right now?
You are allowed to ask if I look for the electron in this little particular part of space
What is the likelihood? I will find it there I?
Mean that bugs anyone
anytime
As weird as it sounds this new way of describing how particles like electrons
Move is actually right when I throw a single electron I can never predict where we’ll land
but if I use Schrodinger’s equation to find the electrons probability wave I
Can predict with great certainty that if I throw enough electrons then say?
33.1% would end up here
7.9% would end up there and so on
these kinds of predictions have been confirmed again and again by experiments and
So the equations of quantum mechanics turn out to be amazingly accurate and precise so
Long as you can accept that it’s all about
probability
If you think that probability means you’re reduced in guessing the casinos of Las Vegas are ready to prove you wrong
Try your hand at any one of these games of chance and you can see the power of probability
Let’s say I place a $20 bet on number 29 here at the roulette table
The house doesn’t know whether I win on this spin with an X or the next one
But it does know the probability that we’ll win in this game. It’s 1 in 38
21
Twenty-nine
So even though I may win now and then in the long run the house always takes him more than it loses
The point is the house doesn’t have to know the outcome of any single card game roll the dice or spin up the roulette wheel
Casinos can still be confident that over the course of thousands of spins deals and rolls
They will win and they can predict with exquisite accuracy
Exactly how often?
According to quantum mechanics the world itself is a game of chance much like this
All the matter in the universe is made of atoms and subatomic
Particles that are ruled by probability not certainty at base
nature is described by an inherently probabilistic theory and
That is highly counterintuitive and something which many people would find difficulty accepting
one person who found it difficult was Einstein Einstein could not believe that the
Fundamental nature of reality at the deepest level was determined by chance, and this is what Einstein could not accept
Einstein said God does not throw dice
He didn’t like the idea that we couldn’t be certain to say this happens or that happens
But a lot of other physicists weren’t so put off by probability
because the equations of quantum mechanics gave them the power to predict the behavior of
groups of atoms and tiny particles with astounding precision
Before long that power would lead to some very big inventions
Lasers
transistors the integrated circuit the
entire field of electronics if quantum mechanics suddenly went on strike
Every single machine that we have in the u.s.. Almost would stop functioning
the equations of quantum mechanics would help engineers design
microscopic switches that direct the flow of tiny electrons and
control virtually every one of today’s computers digital cameras and telephones
All the devices that we live on diodes transistors just to form the basis of information
Technology the basis of daily life in all sorts of ways they work, and why do they work they work because of quanta Kanaks
I’m tempted to say that without quantum mechanics. We’d be back in the dark ages. I
Guess more accurately without quantum mechanics would be back in the 19th century
Steam engines Telegraph signals
Quantum mechanics is the most successful theory that we physicists have ever discovered
And yet we’re still arguing about what it means
What it tells us about the nature of reality?
In spite of all its triumph quantum mechanics remains deeply mysterious it makes all this stuff run
But we still haven’t answered basic questions raised by Albert Einstein all the way back in the 1920s and 30s
questions involving probability and measurement the act of observation
For niels bohr
measurement changes everything
He believed that before you measured or observed a particle its characteristics were uncertain
For example an electron in the double slit experiment
Before the detector at the fact pinpoints its location. It could be almost anywhere with a whole range of possibilities
Until the moment you observe it and only at that point will the locations uncertainty disappear
according to Bohr’s approach to quantum mechanics
When you measure a particle the act of measurement?
forces the particle to relinquish all of the possible places it could have been and
Select one definite location where you find it the act of measurement is what forces the particle to make that choice
Niels Bohr accepted that the nature of reality was inherently fuzzy
But not Einstein he believed in
Certainty not just when something has measured or looked at but all the time
As Einstein said I like to think the moon is there even when I’m not looking at it
That’s what I say
Was was so upset about do we really think the reality of the universe rests on whether or not we happen to open our eyes
That’s just bizarre
Einstein was convinced something was missing from quantum theory
Something that would describe all the detailed features of particles like their locations even when you were not looking at them
but at the time few physicists shared his concern and
ISIF, just thought it was giving up on the job of the physicist it wasn’t bad physics per se just was totally incomplete
That’s einstein’s refrain quantum mechanics is not incorrect. It’s as far as insofar as it goes, but it’s incomplete
It doesn’t capture all the things that can be said were predicted with certainty
Despite Einsteins arguments Niels Bohr remained unmoved when Einstein repeated that God does not play dice
Bohr responded stopped telling God what to do?
But in 1935 Einstein thought he’d finally found the Achilles heel of quantum mechanics
Something so strange so countered all logical views of the universe
He thought it. Held the key to proving the theory was incomplete
It’s called entanglement
The most bizarre
the most absurd
the most crazy the most ridiculous prediction that quantum mechanics maze
Is entanglement?
Entanglement is a theoretical prediction that comes from the equations of quantum mechanics
Two particles can become entangled if they’re close together and their properties become linked
Remarkably quantum mechanics says that even if you separated those particles sending them in opposite directions they could remain entangled
inextricably connected
To understand how profoundly weird this is consider a property of electrons called spin
Unlike a spinning top an electron spin as with other quantum qualities is
generally completely fuzzy and uncertain until
The moment you measure it and when you do you’ll find is either spinning clockwise
Or counterclockwise
It’s kind of like this wheel when it stops turning. It will randomly land on either red or blue
Now imagine a second wheel
If these two wheels behave like two entangled electrons, then every time one landed red
The other is guaranteed to land on blue
and
vice versa
Now since the wheels are not connected
That’s suspicious enough, but the quantum mechanics embraced by Niels Bohr and his colleagues went even further
Predicting that if one of the pair were far away
even on the moon with no wires or
Transmitters connecting them still if you look at one and find red the other is sure to be blue
In other words if you measured a particle here
Not only would you affect it, but your measurement would also affect its entangle partner no matter how distant?
Reinstein that kind of weird long-range connection between spinning wheels or particles was so ludicrous
He called it spooky
spooky action at a distance
What’s surprising?
Is that?
When you make a measurement of one particle you affect the state of the other particle you change its state
There’s no forces or pulleys or you know telephone wires
There’s nothing connecting those things right how could my choice to act here have anything to do with what happens over there?
So there’s no way they could communicate with each other
So it is completely bizarre
Einstein just could not accept that entanglement worked this way
Convincing himself that only the math was weird not reality
He agreed that entangled particles could exist but he thought that there was a simpler explanation
For why they were linked that did not involve mysterious long distance connection
Instead he insisted that entangled particles were more like a pair of gloves
Imagine someone separates the two gloves putting each in a case
Then that person delivers one of those cases to me
And since the other case
grant article
Thanks
Before I look inside my case
I know that it has either left hand or right hand glove and when I open my case
If I find a left hand glove then at that instant I know that case in Antartica must contain a right hand glove
Even though no one has looked inside
There’s nothing mysterious about this obviously by looking inside the case I’ve not affected either
Glove this case has always had a left hand glove and the one in Antarctica has always had a right hand glove
That was said when the moment the gloves were separated and packed away
Now Einstein thought that exactly the same idea applies to entangled particles
Whatever configuration the electrons are in must have been fully determined from the moment that they flew apart
So who was right?
Bohr who championed the equations that said that particles were like spinning wheels
That could immediately link their random results even across great distances
Or Einstein who believed there was no spooky connection, but instead
everything was decided
Well before you looked
Well the big challenge in figuring out who is right Borenstein is that Einstein is saying a
Particle say has a definite spin before you measure it
How do you check that you say to Einstein? He says well measure it and you’ll find the definite spin
Or would say, but it’s the act of measurement that brought that spin to a definite state
No, one knew how to resolve the problem so the whole question came to be considered philosophy not science
in
1955
Einstein died
still convinced that quantum mechanics offered at best an
incomplete picture of reality
In
1967 at Columbia University
Einstein’s mission to challenged quantum mechanics was taken up by an unlikely recruit John
clauser was on the verge of earning a PhD in astrophysics the
Only thing standing in his way was his grade in quantum mechanics
When I was still a graduate student try as I might I could not understand quantum mechanics
Clauser was wondering if Einstein might be right when he made a life-altering discovery
It was an obscure paper by a little-known Irish physicist named John Bell
Amazingly Bell seemed to have found a way to break the deadlock between Einstein and Bohr
and show once and for all who was right about the universe I
Was convinced that the quantum mechanical view was probably wrong
Reading the paper clauser saw that Bell had discovered how to tell if entangled particles were really
communicating through spooky action like matching spinning wheels
Or if there was nothing spooky at all and the particles were already set in their ways like a pair of gloves
What’s more with some clever mathematics Bell showed that if spooky action were not at work
Then quantum mechanics wasn’t merely incomplete as Einstein thought. It was wrong I
Came to the conclusion that my god, this is one of the most profound results I’ve ever seen
Bell was a theorist
But his paper showed that the question could be decided if he could build a machine that created and compared
many pairs of entangled particles
Bell turned the question
Into an experimental question it wasn’t just gonna be about philosophy or trading pieces of paper and the experiment that he envisioned
Could be done. You could really set up an actual experiment to force the issue
Wowser said about constructing a machine that would finally settle the debate
Now I was just this Punk graduate student at the time this really seems like wow
There’s always the slim chance that you will find a result that will shake the world
Clauser x’ machine could measure thousands of pairs of entangled particles and compare their spins in many different directions
As a result started coming in clauser was surprised and not
happy I
Kept asking myself what have I done wrong?
What mistakes have I made it is?
Klaus who repeated his experiments and soon French physicist Elana spay developed a more sophisticated test
With significantly more definitive results as babe removed virtually all lingering doubt
Clauser x’ and s phase results are truly shocking. They prove that the math of quantum mechanics is right
Entanglement is real
Quantum particles can be linked to the cross space
Measuring one thing can in fact instantly affect its distant partners as if the space between them didn’t even exist
The one thing that Einstein thought was impossible
spooky action at a distance actually
happens I
was again
Because I still
To this day still have great difficulty in understanding it
That is the most bizarre thing of
quantum mechanics
It is impossible to even comprehend
Don’t even ask me. Why don’t ask me what you’re going to how it works because it’s an illegal question
All we can say is that is apparently the way the world picks
So if we accept that the world really does tick in this bizarre way
Could we ever harness the long distance spooky action of entanglement to do something useful?
Well one dream has been to somehow transport people in things from one place to another without crossing the space in between
in other words
teleportation
Star Trek has always made being or teleporting looked pretty convenient
It seems like pure science fiction, but couldn’t angleman make it possible
Remarkably tests are already underway here on the Canary Islands off the coast of Africa
We do the experiments here on the Canary Islands because you have two observatories and
After all it’s a nice environment
Anton Zeilinger is a long way from teleporting himself or any other human
But he is trying to use quantum entanglement to teleport tiny
individual particles in this case photons particles of light
He starts by generating a pair of entangled photons in a lab on the island of La Palma
One entangle photon stays on the Palma while the other is sent by laser
to the island of Tenerife
89 miles away
Now Zeilinger brings in a third photon the one he wants to teleport and has it interact with the entangled photon on La Palma
The team studies the interaction
Comparing the quantum states of the two particles, and here’s the amazing part
because of spooky action
the team is able to use that comparison to transform the entangle photon on the distant island into an
identical copy of that third Photon
It’s as if the third photon has teleported across the sea without traversing the space between the islands
Sort of extract the information carried by the original and make a new original there
Using this technique is I linger has successfully teleported dozens of particles
But could this go even further
Since we are made of particles could this process make human teleportation possible one day
Welcome to New York City
Let’s say I want to get to Paris for a quick lunch well in theory
Entanglement might someday make that possible here’s what I need
The chamber of particles here in New York, that’s entangled with another chamber of particles new Harris
Right this way mr.. Green
I would step into a pod that acts sort of like a scanner, or a fax machine
While the device scans the huge number of particles in my body more particles and there are stars in the observable universe
it’s jointly scanning the particles in the other chamber and
It creates a list that compares the quantum state of the two sets of particles
and
Here’s where entanglement comes in because of spooky action at a distance that
List also reveals how the original state of my particles is related to the state of the particles in Paris
Next the operator sends that list to Paris
there they use the data to reconstruct the exact quantum state of every single one of my particles and
a new me
materializes
It’s not that the particles traveled from New York to Paris
it’s that entanglement allows my quantum state to be extracted in New York and
reconstituted in Paris
down to the last particle
Bonjour Monsieur Breen hi there so here I am in Paris an exact replica of myself
And I better be because measuring the quantum state of all my particles in New York has destroyed
The original me it is absolutely required in the quantum teleportation
protocol that the thing that is teleported is destroyed in the process and
You know that does make you a little anxious. I guess you would just end up being a lump of neutrons protons and electrons
You wouldn’t you wouldn’t look too good?
Now we are a long way from human teleportation today
But the possibility raises a question is the Brian Green who arrives in Paris?
Really me
Well there should be no difference between the old me in New York and the new me here in Paris and the reason is that?
According to quantum mechanics, it’s not the physical
Particles that make me me it’s the information those particles contain and that information has been teleported exactly
for all the trillions of trillions of particles that make up my body it is a very different question whether
What arrives at the receiving station?
Is the original or not?
My position is that
By original we mean something which has all the properties of the original
and if this is the case then it is delusional I
Wouldn’t step into that machine
Whether or not human teleportation ever becomes a reality
The fuzzy uncertainty of quantum mechanics has all sorts of other potential applications
Here at MIT Seth Lloyd is one of many researchers trying to harness quantum mechanics in powerful new ways
Quantum mechanics is weird. That’s just the way
It is so you know life is dealing us weird lemons can we make some weird lemonade from this?
Lloyd’s weird lemonade comes in the form of a quantum computer
These are the guts of a quantum computer
This gold and brass contraption might not look anything like your familiar laptop, but at its heart it speaks the same language
Binary code a computer language spelled out in zeros and ones called bits
so the smallest chunk of information is a bit and
What a computer does is simply busts up the information the smallest chunks, and then flips them really really really rapidly
This quantum computer speaks in bits
but unlike a conventional bit which at any moment can be either 0 or 1 a
Quantum bit is much more flexible
You know something here can be a bit here is 0 there is one
That’s a bit of information so if you can have something that’s here and there at the same time
then you have a quantum bit or
qubit
just as an electron can be a fuzzy mixture of spinning clockwise and counter clockwise a
Quantum bit can be a fuzzy mixture of being a 0 and a 1 and
So a qubit can multitask
That it means you can do computations in ways that our classical brains could not have dreamed of
In theory quantum bits could be made from anything that acts in a quantum way like an electron or an atom
The qubits at the heart of this computer are tiny superconducting circuits built with
Nanotechnology that can run in two directions at once
Since quantum bits are so good at multitasking if we can figure out how to get qubits to work together to solve problems
our computing power could explode exponentially
To get a feel for why a quantum computer would be so powerful
imagine being trapped in the middle of a hedge maze
What you want is to find the way out as fast as possible the problem is there are so many options and
I just have to try them out one at a time
That means I’m going to hit lots of dead ends
Go down lots of blind alleys
And make lots of wrong turns
Before I finally get lucky and find the exit and that’s pretty much how today’s computers solve problems
Though they do it very quickly they only carry out one task at a time
Just like I can only investigate one path at a time in the maze
But if I could try all the possibilities at once it would be a different story and that’s kind of how quantum computing works
Since particles can in a sense be in many places at once
The computer could investigate a huge number of paths or solutions at the same time and find the correct one in a snap
Now a maze like this only has a limited number of routes to explore so a conventional computer could find the way out pretty quickly
But imagine a problem with millions or billions of variables
Like predicting the weather far in advance
We might be able to forecast natural disasters like earthquakes or tornadoes
solving that kind of problem right now would be impossible because it would take a
ridiculously huge computer
But a quantum computer could get the job done with just a few hundred atoms and so the brain of that computer
It would be smaller than a grain of sand
There’s no doubt we’re getting better and better at harnessing the power of the quantum world and who knows where that could take us
But we can’t forget that at the heart of this theory which has given us so much
There is still a gaping hole
All the weirdness down at the quantum level at the scale of atoms and particles
Where does the weirdness go?
Y-q things in the quantum world hover in a state of uncertainty
Seemingly being partly here and partly there with so many possibilities while you and I who?
After all are made of atoms and particles
Seem to always be stuck in a single definite state. We are always either here or there
niels bohr offered no real explanation for why all the weird fuzziness of the quantum world seems to vanish as
things increase in size
As
powerful and accurate as quantum mechanics has proven to be
Scientists are still struggling to figure this out
Some believe that there’s some detail missing in the equations of quantum mechanics
And so even though there are multiple possibilities in the tiny world
The missing details would adjust the numbers and our way up from atoms to objects in a big world
So that it would become clear that all but one of those possibilities
disappear
resulting in a single certain
outcome
Other physicists believe that all the possibilities that exist in the quantum world they never do go away
Is that each and every possible outcome actually happened?
only most of them happen in other
Universes parallel to our own
It’s a mind-blowing idea
But reality could go beyond the one universe we all see and be constantly branching off
creating new
Alternative worlds where every possibility gets played out
This is the frontier of quantum mechanics and no one knows where it will lead
The very fact that our reality is much grander than we thought much more
Strange mysterious than we thought is to be also very beautiful and awe-inspiring
The beauty of science is that it allows you to learn things which go beyond your wildest dreams
And quantum mechanics is the epitome of that after you learn quantum mechanics?
Your your never really the same again
As
Strange as quantum mechanics may be what’s now clear is that there’s no boundary between the worlds of the tiny and the big
Instead these laws apply
everywhere, and it’s just that the weird features are most apparent when things are small and
So the discovery of quantum mechanics has revealed a reality our reality
That’s both shocking and thrilling bringing us that much closer to fully understanding the fabric of the cosmos
Major funding for Nova is provided by David H coke and
Discovering new knowledge
Hh mi
And by the Corporation for Public Broadcasting and by
Contributions to your PBS station from viewers like you. Thank you

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