# Casimir Effect

PhysicsQuantum physics

#### Class 11th Physics - Elasticity

6 Lectures 1 hours

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12 Lectures 2 hours

#### Class 11th Physics - Waves

14 Lectures 3 hours

## Introduction

In 1948, two scientists named Casimir and Polder made the following observation: If two uncharged, perfectly conducting plates are placed very close together, they will experience a small attractive force between them. This force became known as the Casimir effect or Casimir force, and it was one of the first demonstrations of zero-point energy ever recorded.

## The Casimir Effect

The most common explanation for the Casimir effect is to say that quantum fluctuations cause energy density fluctuations in an otherwise flat space-time, which causes attraction between particles. But if you think about those kinds of fluctuations, they’re so minuscule that they only produce a force on scales much smaller than what we can see in our daily lives—so how can they be observable here?

That’s where Martin Veltman comes in. Veltman hypothesized that there may be a mechanism by which these tiny forces could become large enough to notice here on Earth. It turns out that moving charges create sound waves, but as you’ve probably noticed, it doesn’t take much movement at all for something to make noise.

So, we can calculate the attractive force between two plates that have area A and distance L by following formula

$$\mathrm{F\:=\:A\frac{\pi hc}{480 \:L^4}}$$

Where,

• h - Plank constant
• c - Speed of light
• F - attractive force

## History of Casimir effect

Casimir effect (aka Casimir force) was formulated by Ludwik Kostro, a Polish physicist. It was originally derived as a result of calculations that were done to establish how two closely spaced conducting plates would act under quantum mechanical conditions. This phenomenon results in forces that pull the plates together and keep them that way, even if the space between them was evacuated of all its matter and energy.

It is a Van der Waals force that exists between any two neutral atoms or molecules that are close enough together for their vacuum-energy levels to overlap. In classical physics, there is no such thing as negative energy, but in quantum mechanics, negative energy states are possible and can play an important role in phenomena like the Casimir effect.

It may seem like magic or something out of science fiction, but it’s actually a very well-studied phenomenon with detailed explanations about why it occurs and how it works.

## Applications of the Casimir Effect

No matter how many times we hear about a new and exciting scientific discovery, we can’t help but be a little bit skeptical. Scientists have developed prototype devices like a quantum-gas microscope based on Casimir effects. They’ve also discovered that self-assembling, microchip-sized bots could be built using these same forces. But sometimes, even everyday discoveries are intriguing in their implications.

The discovery of an exclusion zone around two uncharged metal plates opened up whole new worlds in quantum physics; maybe if you spent some time using these principles to make your next high-tech purchase, you’d be ahead of everyone else!

## Measuring the Casimir Effect

There are many approaches to measuring how far apart two neutral atoms need to be for a measurable force to appear between them.

One approach uses an atom interferometer—placing two identical atoms close together, but not touching. The system creates what’s called a standing wave of quantum behavior in which both particles exist in two states at once—and the distance between them changes, too.

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By observing how that quantum state shifts, scientists can measure what kind of force acts on each particle. Other methods include putting atoms on top of one another or beside one another instead of directly touching them.

This Casimir effect describes the attraction between two parallel uncharged conductive plates due to quantum effects from the electromagnetic field in between them.

## FAQs

Q1. Does the Casimir effect create negative energy?

Ans: The short answer to that question would be no. More specifically, negative energy does not exist. Negative energy is a concept from quantum physics, whereby there’s a movement of particles from one point to another but there’s a difference in potential between those two points which would require energy to create or make that particle move.

Q2. Does the Casimir effect violate the conservation of energy?

Ans: The question of energy conservation isn’t totally settled, but scientists think they have all but proved that E = mc2 is true on a fundamental level. That doesn’t mean there aren’t tricky, weird situations where it seems to be wrong. In some cases, things can balance out—as when quantum fluctuations cause particles to pop in and out of existence from one place only to reappear somewhere else, temporarily balancing out any apparent energy decrease caused by their creation.

Q3. How strong is the Casimir effect?

Ans: Although its existence was predicted in 1948, it wasn’t until 2012 that scientists were able to experimentally confirm something called Casimir force. In recent years, scientists have started using it to levitate tiny objects.

Q4. What is the dynamic Casimir effect?

Ans: The dynamic Casimir effect describes what happens when two objects in a vacuum are pushed together. It was proposed by Hendrik B. G. Casimir, a Dutch physicist, as an explanation for why there is so little empty space between atoms in a crystal lattice, even though 99.9% of space is actually empty.

Q5. What is Coupled Ground State Energy in Casimir effect?

Ans: Quantum mechanics has no problem with such an arrangement. In quantum mechanics, empty space is not really empty. It seethes with pairs of virtual particles popping in and out of existence and other quantum mischiefs (see Spooky Action at a Distance). If two metal plates are parallel to each other within a certain distance, they will attract each other as if they were connected by an imperceptibly thin rod—even though they’re separated by a large gap.

Q6. What causes of the Casimir effect?

Ans: the quantum fluctuation of the electromagnetic field is the main reason for the Casimir effect cause.

Updated on 13-Oct-2022 11:19:47