# Wave / particle duality of light

• cliffhanley203
In summary, the conversation discusses the behavior of light as both a wave and a particle, and how it travels from the Sun to Earth. However, the concept of wave-particle duality is not used in modern quantum theory, and it is not accurate to think of light as a stream of particles traveling through space. Instead, light is quantized and can only change energy by integer amounts, known as photons.
cliffhanley203

## Homework Statement

I've just read that light can behave like a wave at times, and a particle at other times. How does the light from the Sun traveling towards Earth behave? A wave? A particle? Or both? And is it in any sense something that actually starts at the Sun, travels across space and ends up at the Earth; or is it more of a domino effect where something at the Sun causes a chain of effects between the Sun and Earth

## Homework Equations

No relevant equations (that I'm aware of)

## The Attempt at a Solution

When thinking of light as a wave I imagine a Mexican wave of people in a sports stadium where the wave propagates across the stadium by virtue of the people standing up and sitting down. In this scenario the people move up and down but their position doesn't vary (apart from moving up and down; they don't travel across the stadium).

But when thinking of it as a particle I imagine photons (discrete packets of light? quanta of light?) starting at the Sun and traveling across space in a stream so the first quantum of light (the first photon) that left the Sun is the first to arrive here and so on (?)

If anyone is kind enough to help me with this please keep the language very basic as I'm a novice. Thanks.[/B]

You should not think of photons as neither classical particles nor waves. They are quantum particles and have some properties that we typically would associate with a classical particle and some that we would typically associate with a wave - but that does not mean that they are sometimes one and other times the other. Depending on what you are observing, one or the other behavior can be dominant.

Wave-particle duality is not a concept used in modern quantum theory.

To my mind, one should never think of a light beam as stream of particles traveling across space. Quantization of electromagnetic radiation means that the field energy can only be changed by integer numbers of „energy portions“ (called photons) of amount hν, where ν is light frequency and h Planck's constant.

## 1. What is the wave/particle duality of light?

The wave/particle duality of light is a fundamental concept in quantum physics that states that light can behave as both a wave and a particle, depending on the experimental setup. This means that light can exhibit both wave-like properties, such as diffraction and interference, and particle-like properties, such as being able to transfer energy and momentum.

## 2. How was the wave/particle duality of light discovered?

The wave/particle duality of light was first observed in the late 19th century through experiments involving the photoelectric effect, in which light was shown to exhibit particle-like behavior by ejecting electrons from a metal surface. This was later confirmed by experiments such as the double-slit experiment, which demonstrated the wave-like behavior of light.

## 3. What is the significance of the wave/particle duality of light?

The wave/particle duality of light has significant implications for our understanding of the nature of light and the behavior of subatomic particles. It also plays a crucial role in many modern technologies, such as lasers and solar cells, which rely on both the wave and particle properties of light.

## 4. Can other particles exhibit wave/particle duality?

Yes, not only light but all particles can exhibit wave/particle duality. This includes electrons, protons, and even larger particles like atoms and molecules. However, the effects are most noticeable at the quantum level, where the behavior of particles is governed by the laws of quantum mechanics.

## 5. How does the wave/particle duality of light relate to the uncertainty principle?

The wave/particle duality of light is closely linked to the uncertainty principle, which states that it is impossible to know both the position and momentum of a particle with absolute certainty. This means that the more accurately we measure the position of a particle, the less we know about its momentum and vice versa. The wave-like nature of light is also related to its uncertain position and momentum, as described by the wave function in quantum mechanics.

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