What is the energy of a photon in relation to E=MC^2?

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In summary, the equation E=MC^2 only applies to particles in their rest frames, so it does not apply to photons. For photons, the equation E=pc applies, where p is the momentum.
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Lazernugget
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E=MC^2 question about the "M"

So, energy equals mass times the speed of light squared.

Energy can determine speed, because the energy is transferred into the 3 spatial dimensions.

My question is with E=MC^2 itself, Energy of light would equal zero mass times the speed of light squared, right? But that would mean light had zero energy. Care to help explain? I really want to figure this out, and I'm reading the Elegant Universe right now so it would help to understand this before going in too much further.

Thanks,

-Lazer
 
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This question actually comes up a lot. [itex]E = m_{0}c^{2}[/itex] is only valid for particles in their rest frames (the [itex]m_{0}[/itex] is the rest mass). A photon has no rest frame so the equation does not apply to it. In general, [itex]E = \sqrt{(m_{0}c^{2})^{2} + (pc)^{2}}[/itex] so for a photon [itex]E = pc[/itex] where p is the momentum.
 

What is the meaning of "M" in the equation E=MC^2?

The "M" in the equation E=MC^2 represents mass. This means that the amount of energy (E) is equal to the mass (M) multiplied by the speed of light squared (C^2).

Why is the speed of light (C) squared in the equation E=MC^2?

The speed of light (C) is squared in the equation E=MC^2 because it is a constant value and is necessary to convert mass into energy. Squaring the speed of light helps to balance out the units on both sides of the equation.

How does the equation E=MC^2 relate to Einstein's theory of relativity?

The equation E=MC^2 is a result of Einstein's theory of relativity, specifically the special theory of relativity. This theory states that energy (E) and mass (M) are equivalent and are related by the speed of light (C).

What is the significance of the equation E=MC^2 in physics?

The equation E=MC^2 is significant in physics because it explains the relationship between energy and mass, which are two fundamental concepts in the field. It also helps to explain the behavior of matter and energy on a cosmic level.

How is the equation E=MC^2 used in practical applications?

The equation E=MC^2 has practical applications in fields such as nuclear energy, where it is used to calculate the amount of energy released in nuclear reactions. It is also used in particle accelerators and in understanding the behavior of stars and galaxies.

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