This is going to be bugger of a post…Absolutely HUGE, but what can I say?

I can’t help myself in the face of this awesomeness.

I found this amazing article on the seven wonders of the quantum world and boy they weren’t kidding.

These seven wonders ROCK!

Unfortunately you have to bounce around from link to link to get a picture of them all, and since I dislike THAT organization, I saw it as my duty to bring it to you here in a more organized manner…In one big hodgepodge of brain scrambling post.

And well, so it will make it easier for me to find them all in one place later, when I want to revisit them…

But hey, you benefit from this to, now don’t forget.

So everyone is happy. That totally counting. *laughs*

With that said, prepare for the funness that is quantum weirdness. Stretch your brain, squint your eyes in anticipatory concentration, because here we GO:

Seven Wonders of The Quantum World

From undead cats to particles popping up out of nowhere, from watched pots not boiling – sometimes – to ghostly influences at a distance, quantum physics delights in demolishing our intuitions about how the world works.

Wave-Particle Duality

IT DOES not require any knowledge of quantum physics to recognize quantum weirdness. The oldest and grandest of the quantum mysteries relates to a question that has exercised great minds at least since the time of the ancient Greek philosopher Euclid: what is light made of?

History has flip-flopped on the issue. Isaac Newton thought light was tiny particles – “corpuscles” in the argot of the day. Not all his contemporaries were impressed, and in classic experiments in the early 1800s the polymath Thomas Young showed how a beam of light diffracted, or spread out, as it passed through two narrow slits placed close together, producing an interference pattern on a screen behind just as if it were a wave.

So which is it, particle or wave? Keen to establish its reputation for iconoclasm, quantum theory provided an answer soon after it bowled onto the scene in the early 20th century. Light is both a particle and a wave – and so, for that matter, is everything else. A single moving particle such as an electron can diffract and interfere with itself as if it were a wave, and believe it or not, an object as large as a car has a secondary wave character as it trundles along the road.

The Hamlet Effect

A WATCHED pot never boils.” Armed with common sense and classical physics, you might dispute that statement. Quantum physics would slap you down. Quantum watched pots do refuse to boil – sometimes. At other times, they boil faster. At yet other times, observation pitches them into an existential dilemma whether to boil or not.

Imagine, for example, conducting an experiment with an initially undecayed radioactive atom in a box. According to the Schrödinger equation, at any point after you start the experiment the atom exists in a mixture, or “superposition”, of decayed and undecayed states.

Each state has a probability attached that is encapsulated in a mathematical description known as a wave function. Over time, as long as you don’t look, the wave function evolves as the probability of the decayed state slowly increases. As soon as you do look, the atom chooses – in a manner in line with the wave function probabilities – which state it will reveal itself in, and the wave function “collapses” to a single determined state.

This is the picture that gave birth to Schrödinger’s infamous cat. Suppose the radioactive decay of an atom triggers a vial of poison gas to break, and a cat is in the box with the atom and the vial. Is the cat both dead and alive as long as we don’t know whether the decay has occurred?

We don’t know. All we know is that tests with larger and larger objects – including, recently, a resonating metal strip big enough to be seen under a microscope – seem to show that they really can be induced to adopt two states at once (Nature, vol 464, p 697).

The weirdest thing about all this is the implication that just looking at stuff changes how it behaves. [See Quantum Zeno Effect Post, on Anguished Repose]

Casimir Effect

“NOTHING will come of nothing,” King Lear admonishes Cordelia in the eponymous Shakespeare play. In the quantum world, it’s different: there, something comes of nothing and moves the furniture around.

Specifically, if you place two uncharged metal plates side by side in a vacuum, they will move towards each other, seemingly without reason. They won’t move a lot, mind. Two plates with an area of a square metre placed one-thousandth of a millimetre apart will feel a force equivalent to just over a tenth of a gram.

The Dutch physicist Hendrik Casimir first noted this minuscule movement in 1948. “The Casimir effect is a manifestation of the quantum weirdness of the microscopic world,” says physicist Steve Lamoreaux of Yale University.

It has to do with the quantum quirk known as Heisenberg’s uncertainty principle, which essentially says the more we know about some things in the quantum world, the less we know about others. You can’t, for instance, deduce the exact position and momentum of a particle simultaneously. The more certain we are of where a particle is, the less certain we are of where it is heading.

Love The Quantum Bomb

A BOMB triggered by a single photon of light is a scary thought. If such a thing existed in the classical world, you would never even be aware of it. Any photon entering your eye to tell you about it would already have set off the bomb, blowing you to kingdom come.

With quantum physics, you stand a better chance. According to a scheme proposed by the Israeli physicists Avshalom Elitzur and Lev Vaidman in 1993, you can use quantum trickery to detect a light-triggered bomb with light – and stay safe a guaranteed 25 per cent of the time (Foundations of Physics, vol 23, p 987).

The secret is a device called an interferometer. It exploits the quantumly weird fact that, given two paths to go down, a photon will take both at once. We know this because, at the far end of the device, where the two paths cross once again, a wave-like interference pattern is produced (see “Both and neither”).

To visualise what is going on, think of a photon entering the interferometer and taking one path while a ghostly copy of itself goes down the other. In Elitzur and Vaidman’s thought experiment, half the time there is a photon-triggered bomb blocking one path (see diagram).

Only the real photon can trigger the bomb, so if it is the ghostly copy that gets blocked by the bomb, there is no explosion – and nor is there an interference pattern at the other end. In other words, we have “seen” the bomb without triggering it.

Entanglement

ERWIN SCHRÖDINGER called it the “defining trait” of quantum theory. Einstein could not bring himself to believe in it at all, thinking it proof that quantum theory was seriously buggy. It is entanglement: the idea that particles can be linked in such a way that changing the quantum state of one instantaneously affects the other, even if they are light years apart.

This “spooky action at a distance”, in Einstein’s words, is a serious blow to our conception of how the world works. In 1964, physicist John Bell of the European Organization for Nuclear Research (CERN) in Geneva, Switzerland, showed just how serious. He calculated a mathematical inequality that encapsulated the maximum correlation between the states of remote particles in experiments in which three “reasonable” conditions hold: that experimenters have free will in setting things up as they want; that the particle properties being measured are real and pre-existing, not just popping up at the time of measurement; and that no influence travels faster than the speed of light, the cosmic speed limit.

As many experiments since have shown, quantum mechanics regularly violates Bell’s inequality, yielding levels of correlation way above those possible if his conditions hold. That pitches us into a philosophical dilemma. Do we not have free will, meaning something, somehow predetermines what measurements we take? That is not anyone’s first choice. Are the properties of quantum particles not real – implying that nothing is real at all, but exists merely as a result of our perception? That’s a more popular position, but it hardly leaves us any the wiser.

Or is there really an influence that travels faster than light? Cementing the Swiss reputation for precision timing, in 2008 physicist Nicolas Gisin and his colleagues at the University of Geneva showed that, if reality and free will hold, the speed of transfer of quantum states between entangled photons held in two villages 18 kilometres apart was somewhere above 10 million times the speed of light (Nature, vol 454, p 861).

Whatever the true answer is, it will be weird. Welcome to quantum reality.

The Aharonov-Bohm Effect

HERE’S a nice piece of quantum nonsense. Take a doughnut-shaped magnet and wrap a metal shield round its inside edge so that no magnetic field can leak into the hole. Then fire an electron through the hole.

There is no field in the hole, so the electron will act as if there is no field, right? Wrong. The wave associated with the electron’s movement suffers a jolt as if there were something there.

Miracle Matter

FORGET radioactive spider bites, exposure to gamma rays, or any other accident favoured in Marvel comics: in the real world, it’s quantum theory that gives you superpowers.

Take helium, for example. At room temperature, it is normal fun: you can fill floaty balloons with it, or inhale it and talk in a squeaky voice. At temperatures below around 2 kelvin, though, it is a liquid and its atoms become ruled by their quantum properties. There, it becomes super-fun: a superfluid.

Superfluid helium climbs up walls and flows uphill in defiance of gravity. It squeezes itself through impossibly small holes. It flips the bird at friction: put superfluid helium in a bowl, set the bowl spinning, and the helium sits unmoved as the bowl revolves beneath it. Set the liquid itself moving, though, and it will continue gyrating forever.

Parodoxes

It is tempting, faced with the full-frontal assault of quantum weirdness, to trot out the notorious quote from Nobel prize-winning physicist Richard Feynman: “Nobody understands quantum mechanics.”

It does have a ring of truth to it, though. The explanations attempted here use the most widely accepted framework for thinking about quantum weirdness, called the Copenhagen interpretation after the city in which Niels Bohr and Werner Heisenberg thrashed out its ground rules in the early 20th century.

With its uncertainty principles and measurement paradoxes, the Copenhagen interpretation amounts to an admission that, as classical beasts, we are ill-equipped to see underlying quantum reality. Any attempt we make to engage with it reduces it to a shallow classical projection of its full quantum richness.

Lev Vaidman of Tel Aviv University, Israel, like many other physicists, touts an alternative explanation. “I don’t feel that I don’t understand quantum mechanics,” he says. But there is a high price to be paid for that understanding – admitting the existence of parallel universes.

In this picture, wave functions do not “collapse” to classical certainty every time you measure them; reality merely splits into as many parallel worlds as there are measurement possibilities. One of these carries you and the reality you live in away with it. “If you don’t admit many-worlds, there is no way to have a coherent picture,” says Vaidman.

Or, in the words of Feynman again, whether it is the Copenhagen interpretation or many-worlds you accept, “the ‘paradox’ is only a conflict between reality and your feeling of what reality ought to be”.

Come on, you can admit it. That was wonderful, wasn’t it?

*swoon*

I love getting my geek on, don’t you?