How Can Light Have No Mass Yet Transfer Energy?

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In summary, light has no mass because it is always moving and the equation E = mc2 only applies to massive particles at rest. Instead, we use the equation E^2 = (m_{0}c^2)^2 + (pc)^2 to account for light's momentum and energy. Although light has no rest mass, it still carries momentum and can produce heat on our skin.
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danielpherlio
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Ive been looking at the E = mc2 explained on youtube and apparently light has no mass how can it have no mass but you you can feel heat on your skin from light
 
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danielpherlio said:
Ive been looking at the E = mc2 explained on youtube and apparently light has no mass how can it have no mass but you you can feel heat on your skin from light

Why should feeling heat imply mass? That logic doesn't follow.

The equation you posted is for a massive particle at rest. Look up the full version of the equation for a clue on how to apply it to light.
 
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danielpherlio said:
Ive been looking at the E = mc2 explained on youtube and apparently light has no mass how can it have no mass but you you can feel heat on your skin from light

E = mc2 applies only to things that have mass when they are at rest - and light is always moving with speed c, never at rest, so the equation doesn't apply. Instead, we have to use the more general equation:
[tex]E^2 = (m_{0}c^2)^2 + (pc)^2
[/tex]

Here p is the momentum and [itex]m_0[/itex] is the "rest mass" of the object; when people say that light has no mass they mean that its rest mass is zero. Light does however carry momentum (p is non-zero) so there's still some energy to warm your skin.
 
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Thanks nugatory
 
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Light is often described as a wave-particle duality, meaning that it exhibits characteristics of both a wave and a particle. As a particle, it has no rest mass, meaning it does not have any physical substance or matter. However, it does have energy, which is why we can feel the heat from light on our skin.

According to the famous equation, E = mc^2, energy and mass are interchangeable. This means that although light has no mass, it still has energy. When light interacts with matter, it transfers its energy to the particles in the matter, causing them to vibrate and generate heat. This is how we feel the warmth of light on our skin.

Additionally, light is made up of particles called photons, which have no rest mass but do have momentum. This momentum is what allows light to travel and interact with matter, despite not having any mass.

In conclusion, while light may not have mass in the traditional sense, it still has energy and momentum, which allow it to have an impact on the world around us. This is why we can feel heat from light, even though it has no physical mass.
 

1. How can light have no mass?

Light is made up of particles called photons, which have both wave-like and particle-like properties. These particles do not have any rest mass, meaning they do not have any mass when they are not moving. Therefore, light itself does not have any mass.

2. Doesn't everything have mass? How can light be an exception?

While most objects that we encounter in our daily lives have mass, there are certain particles, like photons, that do not have any mass. This is because they travel at the speed of light, which is the maximum speed allowed in our universe. According to Einstein's theory of relativity, objects that travel at the speed of light do not experience time or have a rest mass.

3. If light has no mass, how does it interact with matter?

Even though light itself does not have any mass, it does have energy. This energy is what allows light to interact with matter, such as causing objects to heat up or creating chemical reactions. When light is absorbed by matter, its energy is transferred to the particles of the matter, causing them to vibrate or move.

4. Can light ever have mass?

While light does not have any mass in its natural state, it is possible for light to gain mass under certain conditions. In theory, if light were to slow down or be confined to a small space, it could gain a small amount of mass. However, these conditions are not possible in our universe, so in practical terms, light does not have mass.

5. How does the lack of mass in light affect the study of physics?

The fact that light has no mass has significant implications in the field of physics. It has led to the development of theories such as quantum mechanics and the theory of relativity. Understanding the properties of light has also allowed scientists to make groundbreaking discoveries in areas such as optics and the behavior of electromagnetic waves.

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