# Energy, mass and matter

#### ButchBegy

I need some sources to help me understand the relationships... matter to energy and energy to matter, what is the mechanism?
For example, in my search for information I have seen it stated that a photon of great enough frequency would "decay" into an electron? Is this true? What are some good sources for information.

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#### topsquark

Forum Staff
I need some sources to help me understand the relationships... matter to energy and energy to matter, what is the mechanism?
For example, in my search for information I have seen it stated that a photon of great enough frequency would "decay" into an electron? Is this true? What are some good sources for information.

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The relationship is actually between momentum and energy. You know the Einstein equation $$\displaystyle E = mc^2$$. This relates energy by its rest mass...the mass it has for 0 speed. The more general equation is $$\displaystyle E^2 = (mc^2)^2 + (pc)^2$$ where p is the momentum of the object in a given frame. (Set p = 0 to get $$\displaystyle E = mc^2$$.)

That being said there is no "mechanism" to energy-matter exchange. SR works best (IMHO) when dealing with 4-vectors. There is an energy-momentum 4-vector given by $$\displaystyle \left ( \frac{E}{c}, p_x, p_y, p_z \right )$$. This shows that the energy-momentum transfer really isn't a transfer at all...it merely means that some spatial momentum has transfered itself to the time component of the energy-momentum 4-vector (the E/c part), rather like a rotation of a 3-vector in Classical Physics.

A large energy photon will not create an electron out of the energy. We need to create two particles so that spin can be conserved during the decay. So for this photon to decay we have to create an electron and it's anti-particle the positron for this to occur. The minimum energy that the photon needs to have is $$\displaystyle m_e c^2 + m_p c^2 = 2 m_e c^2$$. Where $$\displaystyle m_e = m_p$$ is the mass of the electron and positron (which has the same mass as the electron since they are anti-particles.)

-Dan

#### ButchBegy

Do you have math that relates the energy of a photon to its frequency?

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#### topsquark

Forum Staff
Do you have math that relates the energy of a photon to its frequency?

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Sure. Planck's theorem says that $$\displaystyle E = h \nu$$.

-Dan

#### Trakas

Seventh. It is knowable by itself being an integrated being. And, it reiterates, it generates the knowledge of itself, by itself.
Eighth. Its properties are immanent to it, that is, they constitute it, and were not created.
Ninth. Life is the property of dynamic matter. This property manifests as organic life when a dynamic entity reaches a certain level of evolutionary integration, that of algae, for example, in which the phenomenon of individuation appears for the first time in the history of the process of evolutionary integration. And much later, in due time, consciousness appears in the beings who reached the last level of evolutionary integration, achieved to date.

1/ The definition of atom that is used is: the atom as basic and indivisible block that composes the matter of the universe, that was postulated by the atomistic school in Ancient Greece, Century V A.C., being Democritus one of its exponents.

Vázquez-Reyna, Mario (2008). Teoría general de la Materia. Borrador. Ciudad de México.