Physics and Magic 001: A Quantum Primer

Today, I’m going to tell you everything I know about quantum mechanics. It won’t take long.

For the lay person, like myself, quantum mechanics is best explained by using analogies, metaphors and similes, because the science part of it is really, really complicated; even the simple explanations come nowhere near being simple. So this approach to quantum mechanics will be a little like knowing that snow is white because it is cold.

Much of the foundation of quantum theory was laid down by a number of really smart theorists in the first quarter of the twentieth century. Among them was Max Planck, a German physicist who was studying thermal radiation.

There was an unexplained variable in such radiation for which Dr. Planck proposed a mathematical solution. His formula depended on a certain assumption of fixed energy productions that he said were “quantized.” He was awarded a Nobel Prize for his work. So were several other physicists who developed the field in the early years of the last century.

Where it gets tricky is that all of these scientists were working on notions about things they couldn’t even see yet: the atom and its parts. Look at it this way:

Imagine you’ve never seen nor heard of the famous coiled-wire toy, the Slinky™. (Can you hear the ad jingle, still resonating in you memory? “It’s Slinky™, it’s Slinky™, oh what a wonderful toy….”) Anyway, imagine you’ve never seen or heard of it. Now imagine you are sitting in a chair, blindfolded, in the middle of a room with a stairway nearby. Someone starts a Slinky™ into its only entertaining trick, coil-hopping down the stairs (in contrast to its single un-entertaining trick, getting tangled into a ball of useless bailing wire).

Okay. You can hear a staccato ringing whine, a regular series of thumps, and you can tell the sound is coming from the direction of the stairs, but you are blindfolded, so you can’t see anything or know exactly where the sound is coming from.

Now, imagine having to describe what is causing the noise, what is happening to cause it, and what you might do to keep the whole thing from entering an “un-entertaining” state. Please show the calculations you use to reach your answer. (Use the back of the page as necessary.)

That’s sort of what the early years of quantum theory development were like. At least in my understanding.

So why do we need quantum theory? Is it just to supply plot devices for Star Trek?

Not exactly. Here’s the central difficulty:

Classical physics, that is, the physics we are all unconsciously familiar with, that explains everything from JELL-O™ to the phases of the moon, has significant shortcomings when it comes to explaining some things on the sub-atomic level. So, when we get right down to electrons and neutrons and protons—and all their more recently discovered siblings and cousins—classical physics falls flat on its face.

For instance, classical physics assumes that you can precisely measure both the momentum and the position of the Slinky™ as it clang-clumps down the stairs. Quantum physics knows that you can’t. (Though, for purposes, this doesn’t really become significant until you’re dealing with individual atoms.) This very, very loosely describes what is known as the Heisenberg Uncertainty Principle, first proposed by Werner Heisenberg, another German theoretical physicist, from his work in the mid- to late 1920s; Heisenberg also received a Nobel Prize. His uncertainty principle states that, by measuring one factor, let’s say momentum, you can only estimate the other factor, position.

Another remarkable discovery of quantum physics is that all matter, including you, me and the sun, exhibit the qualities of both particles (Duh!) and waves (Huh?).

One of the fun controversies (well, I think it’s fun) of quantum theory is called entanglement. It is derived from the work of Austrian physicist Wolfgang Pauli (yup, Nobel Prize) which he described in 1925 and it soon became known as the Pauli Exclusion Principle. It says that two electrons in one system cannot be in the same quantum state; if one electron assumes one state, the other electron automatically assumes the other.

As a consequence, further development of the Pauli Exclusion Principle posited the notion of quantum entanglement. Where the fun comes in is that entanglement suggests that this automatic change will take place no matter how far apart the two electrons are. I mean, they could be really, really far apart.

Here’s an example:

You and your twin both need new shoes. However, the shoes you want are only available in Australia and the shoes your twin wants are only sold in Iceland. Before you leave, though, your father gives you each a smallish gift-wrapped box, a present to entertain you while you’re in your respective hotel rooms in Sidney and Reykjavik.

Father tells you that the gift is a Slinky™, one of your favorite toys. (This will replace your last one, which ended up as a hopeless snarl of colorful wire.) He says that the store only had two left, a red one and a blue one, but he’s not sure which is which, since the gift-wrapping was done by the clerk in the store’s back room. Because of TSA regulations, the gifts will have to be packed in your checked luggage so you won’t be able to open them until you reach your hotels.

What neither you, your twin nor your father knows is that the Slinky™ in each box has no color, but it can only become either red or blue, and one must assume each color because that’s what the store’s inventory stated.

Your flight to Australia is direct, but your twin must make connections in Atlanta. Consequently, you reach your hotel room in Sidney while your twin is still riding in a cab from the Reykjavik airport.

As you begin to tear the decorated paper from the box, you cry excitedly, “I hope it’s the blue one.” At which point yours becomes blue and your twin’s Slinky™, on the opposite side of the earth, instantly becomes red. (Hmm? Entanglement. Maybe Slinky™ wasn’t the best example.)

However, Albert Einstein (Nobel Prize) who had made his own contributions to the need for quantum mechanics, had trouble swallowing this idea whole; he referred to it as “spooky action at a distance.” But, remember, he’s been wrong before.

There might be one or two other things we could cover, but I think this is more than enough for now. Certainly it goes way beyond my area of competence. Maybe you should just read the Wikipedia entry on quantum mechanics—like I did. Then maybe you could explain it to me.

—  -  —  -  —  -  —  From the news  —  -  —  -  —  -  — 

Ultrafast Quantum Computer Closer: Ten Billion Bits of Entanglement Achieved in Silicon

ScienceDaily (Jan. 22, 2011) — Scientists from Oxford University have made a significant step towards an ultrafast quantum computer by successfully generating 10 billion bits of quantum entanglement in silicon for the first time -- entanglement is the key ingredient that promises to make quantum computers far more powerful than conventional computing devices. (Link to article)

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