The one thing you can say with any certainty about quantum physics is that there is no certainty about quantum physics. During the first part of the 20th century, physicists and mathematicians turned their minds to the study of the unseen components of our world: atoms, elections and even subatomic particles. While the laws of physics worked reliably in the larger sphere -- a dropped object always falls down, two objects can't occupy the same space at the same time and so on -- these scientists were perplexed to discover that this new physics seemed to be a law unto itself. Physicist Max Planck called the tiny particles of light he was studying quanta, and he came to realize that light isn't a continuous wave, but exists with an arbitrary amount, or quanta, of energy. Thus the term "quantum physics" was born [source: PBS].
The baffling part about quantum physics is that unlike its inflexible forebear, classical physics, the rules keep changing and the results of an experiment or equation can't be predicted. Often, physicists are as shocked by the results as anyone. Sometimes, the theories can't be proved except by imaginary experiments. After more than a century, quantum physics continues to be a source of mystery and amazement.
In this article, we'll take a look at some of the questions most commonly asked about quantum physics. We'll explore some practical applications of this bizarre science and examine some of its more esoteric aspects -- the possibility that the universe exists only in our minds and the search for the "God particle."
10. Does anybody really understand quantum physics?
In a word, no. Standard physics is predictable in that everything works the same way, all the time. In the world of standard physics, if you throw a baseball, you know in what direction it will go. In the bizarre world of quantum physics, that ball could wind up anywhere. It could even disappear and reappear again years from now. But while some principles of quantum physics make your head hurt -- parallel universes come to mind -- physicists do understand enough of some principles of quantum physics to come up with some practical applications. It's kind of like operating a car -- you don't have to know how it works mechanically in order to drive to the store.
All of this doesn't mean that there aren't ways to prove the principles of quantum physics. Keep reading to discover the creative methods scientists have developed to explain their theories.
9. How do you prove what you can't see?
Scientists test theories about things they can't see by coming up with experiments that could show them the result, even if they can't see what's going on during the process. Many times, this must be a hypothetical problem that doesn't really have a solution, but rather serves as an example to help the researchers reason out possible scenarios. Schrodinger's Cat is probably the most famous example, but there are countless others. Some of these "thought experiments" couldn't be carried out when they were developed, but now we have the technology to perform them, and, more often than not, the early theories have proven correct [source: Mayes]. Often, the answer lies in a mathematical equation. Those who work with quantum physics have learned to try all possibilities, even those that seem improbable. Planck discovered the existence of the photon through just such an act of desperation [source: PBS].
8. How can you be certain about anything that has an "Uncertainty Principal" at its core?
The Uncertainty Principle, which says that more than one aspect of a particle cannot be measured simultaneously, illustrates one of several major differences between quantum physics and classical physics. This idea, first presented by Heisenberg, takes into account that a miniscule bit of material can be either a particle or a wave, depending on the circumstance. Actually, it is neither, until someone looks at it or an experiment forces it to pick sides. This means that a number of qualities aren't defined. If a scientist measures the speed of a particle, for instance, he can't measure position very accurately; it's as though quantifying one aspect puts the other aspects more out of focus. Physicists know this and try to compensate for it in their experiments. Still, the word "uncertainty" is there for a reason. Some physicists say this is not a principle at all and instead prefer to call the concept "uncertainty relations" [source: Hilgevoord and Uffink].
7. Are we close to proving the theories of Planck, Bohr and Heisenberg?
We can prove Bohr's Copenhagen Interpretation through the Double Slit Experiment, which calls for you to create a wall with two holes in it and another wall behind. Light projected on the front wall will travel through both holes and form a consistent pattern on the back wall. When one particle is shot at the wall, it will create a different pattern. This is exactly what it should do since it can only travel through one hole at a time. But this is only if someone's watching. If no one is observing the particle, the pattern created is the same as if the particle were going through both holes. This is a practical representation of the theoretical Schrodinger's Cat problem.
In another practical proof of the Copenhagen Interpretation, quantum cryptography protects encoded information from hackers by altering the data if someone accesses it [source: Cho].
6. How exact is the math that determines probability?
Since we've gotten this far with just probabilities and bizarre truths, why would you think the mathematics involved in quantum physics would be normal? Of course it's not. The first mathematics used in quantum physics was based on matrices, or grids of numbers, but just a few weeks after those matrices were published, Schrodinger published his system of wave mathematics. Results for both types of math turned out to be comparable. However, experiments with Bohr in Copenhagen proved that the waves were not continuous. The particles jumped from one quantum state to another, leading Schrodinger to remark, "Had I known that we were not going to get rid of this damned quantum jumping, I never would have involved myself in this business" [source: Oracle ThinkQuest Education Foundation].
A branch of quantum physics called quantum electrodynamics poses another kind of problem as it attempts to explain electromagnetic interaction. When wave mathematics is used, you get an electron with infinite mass and energy. This isn't possible, but there's no way to get rid of the result, so the physicists just settle on an answer they think is correct [source: Oracle ThinkQuest Education Foundation].
5. How solid is string theory?
String theory, sometimes called "the theory of everything," purports to provide a unified theory of the structure of everything in the universe. In string theory, a particle, instead of being a point, is a string, which can oscillate in many directions. If it oscillates one way, we call it an electron; if it oscillates another way, we say it's a proton. The possibilities are endless [source: Guijosa].
Critics make several arguments against string theory, although few are calling for it to be abandoned entirely. Some people call string theory into question because the string theorists can't make a prediction and then formulate an experiment to prove its validity. Others say that the true science behind string theory has been exaggerated. Some critics have even gone so far as to call the string theorists a cult [source: Jones].
4. How can quantum physics concepts be used for good?
Even though quantum physics is still full of surprises, researchers are using some of its concepts to create new technologies that can be used to better the world. That "fasten your seatbelt" light on airplanes may soon be a thing of the past, thanks to quantum turbulence experiments conducted by researchers in Brazil [source: American Institute of Physics]. As we've discussed, quantum cryptography can safeguard data on computers, while quantum computing will help those computers run faster [source: University of California - Santa Barbara].
An aspect of quantum physics called entanglement -- the quantum interconnection of atoms separated by distance -- may help make solar energy more accessible [source: American Institute of Physics]. Scientists have also discovered that algae may use quantum mechanics to store energy in two places at once, perhaps setting an example for how we can use quantum principles even if we don't understand them [source: University of Toronto]. The field of medicine, both traditional and alternative, offers many possibilities for the use of quantum physics concepts, from the identification of cancer cells to promoting healing energies through prayer, something we'll look at later.
3. How are particle accelerators helping study and control particles?
It seems ironic that the largest and most expensive pieces of scientific equipment are used to study the tiniest and most basic components of the universe. Particle accelerators, sometimes called atom smashers or colliders, push particles to the speed of light and shoot them through a tube into an electric field. Magnetic forces control the paths of the particles, and each eventually collides with a still target or another moving particle. Scientists analyze the wreckage after the collision.
Work with accelerated particles is helping physicists develop a list of the particles that make up the nuclei of atoms. They've already discovered several hundred and say someday this list will be as valuable as the periodic table is to chemistry. Eventually, they hope to get to the heart of the universe by mimicking conditions when the universe was formed. Scientists have learned more about the subatomic world through work with particle accelerators than through any other means [source: Egglescliffe]. The Large Hadron Collider (LHC), the world's largest particle accelerator, is underground below the border between France and Switzerland. The first proton-proton collisions in the LHC took place in 2009. CERN, the European Organization for Nuclear Research, operates the LHC [source: Achenbach].
2. How do parallel universes work?
Ever wonder what your life would have been like if you'd had the nerve to ask the head cheerleader to the prom? What if you'd majored in business instead of getting an art degree? What would the world be like today if the Axis powers had been victorious in World War II? The answers to all these questions exist in the world of quantum physics. In fact, you're living those lives. In the quantum world, there are no missed opportunities.
While we don't know the technicalities of how parallel universes work, most quantum physicists believe they exist. The parallel universe theory says everything freezes during observation, then splits. Every choice is taken, leading to an infinite number of universes. An experiment reported in the spring of 2010 seems to indicate this. Researchers at the University of California - Santa Barbara isolated a tiny tuning fork, struck it and observed that it moved and stood still at the same time. They say it's proof that observing an object and action splits the universe into two parts -- one we can see and one we can't. Scientists are trying to figure out how to get from the world we will enter into the one we won't [source: Brandon].
1. What is the spiritual aspect of quantum physics?
Throughout history, humans -- whether through shamans invoking animal spirits or priests using the rites of the Christian church -- have believed that the spirit world can influence events on Earth. Now, scientific studies are showing that our thoughts may indeed create our own reality. Bohr said reality was dependent on an "observer effect," that observation can influence events. While many scientists discounted this idea, recent experiments are showing that it may have some merit [source: Lyon]. The repetitive words and actions of a religious service may alter reality, the studies show, and the more people who observe and participate in these rites, the more powerful the waves of energy produced, confirming what the faithful say they've known all along.
Lots More Information
- 10 Ways Quantum Physics Will Change the World
- 10 Real-world Applications of Quantum Mechanics
- 10 Science Experiments That Changed the World
- Famous Physicists Pictures
- Fact or Fiction: The Practical Side of Quantum Mechanics
- Quantum Physics Quiz
- Achenbach, Joel. "The God Particle." National Geographic. March 2008. (Aug. 30, 2010) http://ngm.nationalgeographic.com/2008/03/god-particle/achenbach-text
- Bormanis, Andre. "Star Trek Cult: Combat Forces." BBC. (Nov. 2, 2010) http://www.bbc.co.uk/cult/st/interviews/bormanis/page38.shtml
- Brandon, John. "Freaky Physics Proves Parallel Universes Exist." Fox News. April 5, 2010. (Sept. 2, 2010) http://www.foxnews.com/scitech/2010/04/05/freaky-physics-proves-parallel-universes/
- Cho, Adrian. "Quantum Cryptography Hits the Fast Lane." Science. April 19, 2010. (Aug. 30, 2010) http://news.sciencemag.org/sciencenow/2010/04/quantum-cryptography-hits-the-fa.html
- Comstock, Paul. "The Strange World of Quantum Entanglement." California Literary Review. March 30, 2007. (Aug. 30, 2010) http://calitreview.com/51
- Egglescliffe School. "Particle Accelerators." (Nov. 2, 2010) http://www.egglescliffe.org.uk/physics/particles/newfolder/acc1.html
- Guijosa, Alberto. "What is String Theory?" Universidad Nacional Autonoma de Mexico. Sept. 9, 2004. (Sept. 6, 2010) http://www.nuclecu.unam.mx/~alberto/physics/string.html
- Hilgevoord, Jan and Jos Uffink. "The Uncertainty Principle." Stanford Encyclopedia of Philosophy. July 3, 2006. (Nov. 1, 2010) http://plato.stanford.edu/entries/qt-uncertainty/
- Institute of Physics. "Does anyone understand quantum mechanics?" March 25, 2009. (Nov. 1, 2010) http://www.physics.org/featuredetail.asp?id=33
- Jones, Andrew Zimmerman and Daniel Robbins. "String Theory for Dummies." Wiley Publishing Inc. 2010.
- Lyon, William S. "Shamanic Healing: Why It Works." Beliefnet. (Aug. 30, 2010) http://www.beliefnet.com/Faiths/Pagan-and-Earth-Based/2003/12/Shamanic-Healing-Why-It-Works.aspx?p=1
- Massachusetts Institute of Technology. "New Material Puts Its Own Spin On Electronics; Could Greatly Increase Computing Power." ScienceDaily. May 29, 2006. (Aug. 30, 2010) http://www.sciencedaily.com/releases/2006/05/060528161422.htm
- Mayes, Keith. "What is quantum mechanics?" 2004. (Nov. 11, 2010) http://www.thekeyboard.org.uk/Quantum%20mechanics.htm
- Nobel Media. "Interpreting the Quantum World." 2010. (Nov. 3, 2010) http://nobelprize.org/educational/physics/quantised_world/interpretation-2.html
- Oracle ThinkQuest Education Foundation. "What is Quantum Physics?" (Aug. 30, 2010) http://library.thinkquest.org/3487/qp.html
- PBS. "Quantum Mechanics." 1999. (Aug. 30, 2010) http://www.pbs.org/transistor/science/info/quantum.html
- Rowe, Aaron. "Quantum Dots Glow Where Cancer Cells Grow." Wired Science. June 22, 2007. (Aug. 2, 2010) http://www.wired.com/wiredscience/2007/06/quantum-dots-gl/
- University of Toronto. "Quantum Mechanics at Work in Photosynthesis: Algae Familiar With These Processes for Nearly Two Billion Years." ScienceDaily. Feb. 4, 2010. (December 17, 2010)http://www.sciencedaily.com/releases/2010/02/100203131356.htm