Hendrik Casimir's idea for his experiment was simple: bring two metal objects very close together and wait. Involuntarily, by magic, objects come closer. No external forces, no push or pull, no action of gravity, tension or magnetism. Objects just move closer. What is the reason? An infinite source of vibration in the vacuum of space-time.
This historic experiment, first designed by Casimir after World War II – and carried out 25 years ago – paved the way for scientists to see the manifestations of quantum theory in a real and practical way. Quantum fields and their resonances drive our modern understanding of physics, from subatomic interactions to the evolution of the entire universe. Thanks to Casimir's work, what we have learned is that infinite energy permeates the vacuum of space. There are many ideas in the science fiction universe that propose using vacuum energy to power a starship or other advanced propulsion such as a warp drive. While these ideas are still dreams, the truth is that a simple experiment developed in 1948 set fire to our imagination and our understanding of the universe.
Casimir, a Dutch physicist who spent his undergraduate years under the tutelage of Niels Bohr, one of the fathers of quantum physics, fell in love with this new and unusual theory of the universe. But as soon as quantum theory emerged, it began to make very strange claims about the universe. The quantum world is strange, its ultimate strangeness usually invisible to us, operating at scales far below our normal human perception or observation. Casimir began to wonder how we could test these ideas.
He discovered an ingenious way to measure the effects of infinite, ever-present quantum fields by using pieces of metal in close proximity. Their work shows that quantum behavior can manifest itself in surprising ways that we can measure. It showed that the strangeness of quantum behavior is real and cannot be ignored, and that you have to believe what quantum mechanics says about the workings of the universe, no matter how strange it is.
Quantum fields are otherworldly, but very real
One of the lessons of the quantum world is that particles like electrons, photons, and neutrinos are not what they appear to be. In fact, every particle we see in nature is a part of something much larger. These large entities are called quantum fields, and like oil and vinegar soaking a piece of bread, the fields permeate all space and time throughout the universe.
Each type of particle has a quantum field: one field for electrons, another for photons, and so on. These fields are invisible to us, but they are fundamental pillars of existence. They vibrate and hum constantly. When the fields vibrate with enough energy, particles appear. When the fields are turned off, the particles disappear. Another way of looking at it is that what we call a “particle” is actually a localized vibration of a quantum field. When two particles interact, they are actually two pieces of quantum fields interacting with each other.
These quantum fields always vibrate, even if those vibrations are not strong enough to form a particle. If you take a box and empty it of all its contents — all the electrons, all the photons, all the neutrinos, everything — the box is still full of these quantum fields. Because those fields vibrate even in isolation, the box is filled with invisible vacuum energy, also known as zero-point energy: the energy of those fundamental vibrations.
In fact, you can count how many resonances there are in each of these quantum fields … and the answer is infinity! There are small, medium, large, and colossal, and they all continue to pile together, as if spacetime were boiling at a subatomic level. This means that the vacuum of the universe is actually made of something. There is no real emptiness; Wherever you go, there are always vibrant quantum fields.
A simple experiment with multiple infinities
This is where Casimir's experiment comes in: if we take two metal plates and stick them very, very close together, the quantum fields between the plates must behave in a certain way: the wavelengths of their vibrations must match exactly between the plates. The vibrations of a guitar string must adjust their wavelengths to the length of the string. In the quantum case, there are still an infinite number of vibrations between the plates, but – and this is important – not an infinite number of vibrations between the plates.
What does this mean? In mathematics, not all infinities are the same, and we have developed intelligent tools to compare them. For example, consider the infinity type where consecutive numbers are added to each other. You start with 1, then you add 2, then you add 3, then you add 4, and so on. If you add numbers indefinitely, you will reach infinity. Now let's consider another type of addition, in this case powers of 10. You start with 101, add 102, 103, 104 and so on.
Casimir's experiment brings two metallic objects very close together. Objects move closer due to the vibration of the quantum field and no other force.
Again, if you continue this series forever, you will reach infinity. But in a certain sense you will soon “get there” to infinity. So by carefully subtracting these two series, we can get the magnitude of their difference even if they both go to infinity.
Thanks to this clever mathematical trick, we can achieve two types of infinities – those between the metal plates and those outside – and a finite number. This means that there are actually more quantum vibrations inside the two plates than outside. This phenomenon leads to the conclusion that quantum fields outside the plates push the two plates together, a phenomenon called the Casimir effect in honor of Hendrik.
The effect is incredibly small, about 10 to 12 newtons, and the metal plates must be less than one to one micrometer across. (One newton is the force that accelerates a 1 kilogram object 1 meter squared per second). So, although Casimir was able to predict the existence of this quantum effect, it was not until 1997 that Yale physicist Steve Lamoureux was able to measure it.
Quantum physics in action
Perhaps most strangely, the creature with the deepest connection to the fundamental quantum nature of the universe is the gecko. Geckos can walk on walls and even ceilings. To do this, their ends are covered with countless fine hair-like fibers. These fibers get close enough to the molecules of the surface they want to climb for the Casimir effect to work. An attractive force is created between the hair and the surface. Each hair provides very little force, but together they are enough to support the gecko.
In this test setup mounted on the kitchen counter, foods don't magically come together. Instead, infinitely vibrating quantum fields push them from the outside of space-time.
We normally do not see, feel or experience the Casimir effect. But when we want Design micro- and nano-scale machines, we must take these additional forces into account. For example, researchers have designed microscale sensors that can monitor the flow of a chemical molecule through a molecule, but the Casimir effect can disrupt the sensor's functionality if we don't know about it.
Scientists are exploring the potential of vacuum energy
For years, researchers have been exploring the possibility of extracting energy from the vacuum and using it as an energy source. It was patented in 2002 A device that charges a battery by capturing the electrical charges of two metal plates in Casimir's experiment. The device can be used as a generator. According to the patent, “multiple metal plates are mounted around a hub and rotate like a gyrocompass to generate continuous force”.
US Department of Defense Defense Advanced Research Projects Agency (DARPA). Researchers were awarded $10 million in 2009 To deepen the knowledge of Casimir's strength. Although advances in the actual use of vacuum energy have been gradual, the researchers said at the time that this line of energy research could lead to innovations in nanotechnology, such as creating a device capable of levitation.
Research Group at the University of Colorado at Boulder Garrett model It has developed devices that produce energy that “appears to be the result of quantum zero-point energy fluctuations.” According to the group's website. Their device essentially recreates Casimir's experiment, creating an electric current between two metal layers that the researchers were able to measure, even without applying an electrical voltage.
As for Casimir, immersed in the burgeoning quantum revolution at Leiden University, he had a tendency to underestimate his own work. In his autobiography, A confusing reality, Casimir said: “The story of my own life is not particularly interesting.” And his monumental 1948 paper ends with a simple statement framing his experiment: “Although the effect is small, an experimental confirmation does not seem impossible and may be of some interest.”
Indeed, his initial idea did not cause a stir in the scientific community, nor were there any glowing accounts of his experiment in the popular press. This was partly due to Casimir's own modesty, and partly because he abandoned academic research to devote himself to industry. But despite these humble beginnings, his work cannot be underestimated.
Nowadays, We are constantly perfecting Casimir's original experimental set-up looks for cracks in our theories, and we use this as a basis for probing more deeply into the fundamental nature of the universe.
Paul M. Sutter A science educator and theoretical cosmologist Institute for Advanced Computational Sciences at Stony Brook University and How to Die in Space: A Journey Through Dangerous Astrophysical Phenomena And Your Place in the Universe: Understanding Our Big, Messy Existence. Sutter is also the host of various science shows and is active on social media. Look at him Ask an astronaut Internet And his YouTube page.
