How the concept of virtual particles could underlie reality

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This article was originally published Conversation. The publication contributed to the article on Space.com Expert Voices: Op-Ed & Insights.

A clever mathematical tool known as virtual particles unlocks the strange and mysterious inner workings of subatomic particles. What happens to these particles in atoms would remain unexplained without this tool. Calculations using virtual particles predict the strange behavior of subatomic particles with such incredible accuracy that some scientists believe “they really must exist.”

Virtual particles aren’t real—as their name suggests—but if you want to understand how real particles interact with each other, they’re unavoidable. They are essential tools for describing three forces in nature: electromagnetismand the strong ones and weak nuclear forces.

Real particles are bits of energy that can be “seen” or detected by appropriate instruments; this property makes them perceptible or real. Virtual particles, on the other hand, are a complex mathematical tool and cannot be seen. Physicist Richard Feynman invented them to describe the interactions of real particles.

But many physicists are not convinced by this cut-and-dried distinction. Although scientists cannot detect these virtual particles as computational tools predict many subtle effects that extremely sensitive experiments confirmed the mind-boggling 12 decimal places. This accuracy is like measuring the distance between the North and South Poles to better than a hair’s breadth.

This level of agreement between measurements and calculations makes virtual particles the most tested idea in science. This leads some physicists to ask: Can a mathematical tool become real?

Accounting tool

Virtual particles are a tool that physicists use to calculate how forces work in the microscopic subatomic world. Forces are real because they can be measured.

But instead of trying to calculate forces directly, physicists use an accounting system in which short-lived virtual particles carry the force. Virtual particles not only make calculations more manageable, but also solve a long-standing problem in physics: How does force work in empty space?

Virtual particles exploit the natural fuzziness of the subatomic worldwhere, if these short-lived particles live short enough, they can also be short-lived borrow your energy from empty space. Dizziness of energy balance hides this short imbalancewhich allows virtual particles to affect the real world.

One big advantage of this tool is that the mathematical operations describing the forces between particles can be visualized as diagrams. They usually look like cartoons where particle ping pong is played with virtual particles. Diagrams are duplicated Feynman diagrams – offers a great intuitive system, but also gives the virtual particles an aura of deceptive reality.

Amazingly, this virtual particle-based computing method produces some of the most accurate predictions in all of science.

Reality check

All matter is made up of basic building blocks called atoms. Atoms, in turn, are made of small positively charged particles called protons found in their core, surrounded by even smaller ones negatively charged particles called electrons.

As a professor in physics and astronomy from Mississippi State UniversityI perform experiments that often rely on the idea that the electrons and protons we see in our devices interact to exchange virtual particles. My colleagues and I recently measured proton size very precisely by bombarding hydrogen atoms with a beam of electrons. This measurement assumes that the electrons can “sense” the proton in the center of the hydrogen atom, exchanging virtual photons: electromagnetic energy particles.

Physicists use virtual particles to calculate with extreme precision how two electrons repel each other. The associated forces are represented as the cumulative effect of two electrons trading virtual photons.

When two metal plates are very close to each other in a vacuum, they attract each other: this is known as Casimir effect. Physicists can precisely calculate the force that pulls the plates together using virtual particle mathematics. Whether virtual particles really exist or not, the math accurately predicts what researchers observe in the real world.

Another mysterious prediction made using the Virtual Particle Toolkit is the so-called Hawking radiation. When virtual particle pairs appear at its edge black holes, sometimes the black hole’s gravity grabs one partner and the other escapes. This gap causes the black hole to slowly evaporate. Although Hawking radiation has not yet been directly observed, scientists have recently done so observed it indirectly.

Useful fiction

Back to the question: Can a mathematical tool become real? If you can perfectly predict everything about the force by imagining it carried by virtual particles, do these particles count as real? Does their fictional status matter?

Physicists remain divided on these questions. Some prefer to “just shut up and count,” one of Feynman’s most famous quips. Currently, virtual particles are the best way to describe particle behavior. But scientists are evolving alternative methods that they are not needed at all.

If these methods are successful, virtual particles may disappear forever. Successful or not, the fact that alternatives exist at all suggests that virtual particles may be a useful fiction rather than a physical truth. This also fits the pattern of previous scientific revolutions – the example of the ether comes to mind. Physicists invented the ether as a medium through which light waves travel. The experiments were in perfect agreement with the calculations using this tool, but they couldn’t actually detect it. Ultimately, Einstein’s theory of relativity showed that it was unnecessary.

Virtual particles are a striking paradox of modern physics. They shouldn’t exist, but they’re necessary to calculate everything from the strength of magnets to the behavior of black holes. They reflect a deep dilemma: sometimes the best insights into reality come through a carefully constructed illusion. After all, confusion about virtual particles may just be the price of understanding fundamental forces.

This article is reprinted from The Conversation under Creative Commons license. Read it original article.