Reconciling an Ordinary World

Featured Blogger / by Chad Orzel /

Advances in materials and techniques bring physicists a step closer to observing the oddities of quantum behavior at the real-world scale.

One of the most vexing things about studying quantum mechanics is how maddeningly classical the world is. Quantum physics features all sorts of marvelous things—particles behaving like waves, objects in two places at the same time, cats that are both alive and dead—but we don’t see those things in the world around us. When we look at an everyday object, we see it in a definite classical state and not in any of the strange combinations of states allowed by quantum mechanics. Particles and waves look completely different, dogs can only pass on one side or the other of an obstacle, and cats are stubbornly alive or dead, not both at once.

Over the last 80 or so years, physicists have struggled to discover the origin of this apparent division between the quantum and classical worlds. Niels Bohr treated it as axiomatic in the “Copenhagen interpretation” of quantum theory, but this was an ad hoc addition to the theory. Nothing in the core equations of the theory says that a cat can’t be in two states at once, and physicists have had to work very hard to find possible explanations for why this doesn’t happen, proposing additions to the Schrödinger equation or invoking quantum gravity.

In recent years, new advances in materials and experimental techniques have made it possible to see quantum behavior in larger and larger objects, and a sort of cottage industry has sprung up in looking for quantum behavior of macroscopic objects. The DAMOP meeting in May featured an entire invited session on the subject with speakers from Yale, Vienna, and Munich, and another talk on experiments at LIGO that have pushed gram- and kilogram-scale mirrors toward the quantum limit (article here).

In “Quantum Mechanics in Ordinary Objects,” Veronique Greenwood reports on the latest development in this fast-growing field, a new experiment from the group of Michael Roukes at Caltech. The Roukes group has manufactured a “bridge” two micrometers in length next to an “artificial atom” consisting of a small loop of superconductor. The two are close enough together that their motion is coupled—when the “atom” is in a higher energy state, the “bridge” vibrates at a higher frequency, and vice versa. They have used the vibration of the “bridge” to detect the state of the “atom” and observed the discrete energy steps that give quantum mechanics its name. In the future, they hope to reverse the experiment, and use the state of the “atom” to detect quantized vibrations in the “bridge,” when the whole system is cooled down to low enough energy. Then they can try to prepare the “bridge” in a superposition of two states at once, and see what happens.

The Caltech group is still a long way from observing a cat in two places at once—only a physicist would consider a mass of 40 trillionths of a gram “macroscopic”—but this would be the largest object by far ever to show unambiguous quantum behavior. If they succeed, it could provide new insight into why the world we see is so depressingly ordinary compared to the world of quantum theory.

Discuss this article at ScienceBlogs »

Originally published July 29, 2009

Tags limits research scale theory

Share this Stumbleupon Reddit Email + More

Now on SEEDMAGAZINE.COM

  • Ideas

    I Tried Almost Everything Else

    John Rinn, snowboarder, skateboarder, and “genomic origamist,” on why we should dumpster-dive in our genomes and the inspiration of a middle-distance runner.

  • Ideas

    Going, Going, Gone

    The second most common element in the universe is increasingly rare on Earth—except, for now, in America.

  • Ideas

    Earth-like Planets Aren’t Rare

    Renowned planetary scientist James Kasting on the odds of finding another Earth-like planet and the power of science fiction.

The Seed Salon

Video: conversations with leading scientists and thinkers on fundamental issues and ideas at the edge of science and culture.

Are We Beyond the Two Cultures?

Video: Seed revisits the questions C.P. Snow raised about science and the humanities 50 years by asking six great thinkers, Where are we now?

Saved by Science

Audio slideshow: Justine Cooper's large-format photographs of the collections behind the walls of the American Museum of Natural History.

The Universe in 2009

In 2009, we are celebrating curiosity and creativity with a dynamic look at the very best ideas that give us reason for optimism.

Revolutionary Minds
The Interpreters

In this installment of Revolutionary Minds, five people who use the new tools of science to educate, illuminate, and engage.

The Seed Design Series

Leading scientists, designers, and architects on ideas like the personal genome, brain visualization, generative architecture, and collective design.

The Seed State of Science

Seed examines the radical changes within science itself by assessing the evolving role of scientists and the shifting dimensions of scientific practice.

A Place for Science

On the trail of the haunts, homes, and posts of knowledge, from the laboratory to the field.

Portfolio

Witness the science. Stunning photographic portfolios from the pages of Seed magazine.

SEEDMAGAZINE.COM by Seed Media Group. ©2005-2012 Seed Media Group LLC. All Rights Reserved.

Sites by Seed Media Group: Seed Media Group | ScienceBlogs | Research Blogging | SEEDMAGAZINE.COM