# What came first, matter or energy?

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mfb
Mentor
It happens both in experiments and in nature.
Matter has energy, this energy can be converted to different forms of energy.

But it says it is converted into matter not into different forms of energy. Could you give me some examples of this happening in nature?

jbriggs444
Homework Helper
2019 Award
But it says it is converted into matter not into different forms of energy. Could you give me some examples of this happening in nature?
Matter has rest energy according to E=mc2. Annihilate an electron and an anti-electron and you get two photons, neither of which has a non-zero rest mass. [The wikipedia article appears to take the position that "matter" is composed of particles with non-zero rest mass].

You can google "pair production" for the reverse interaction.

mfb
Mentor
Matter is a form of energy.

Examples in nature: high-energetic cosmic rays produce new particles if they hit something. It is basically the same process we can also do in a lab. High-energetic photons from gamma decays can also do pair-production naturally.

Matter is a form of energy.
Energy is a property of matter.

I am doing something terribly wrong here because I can't get my head around how these two statements can be both true.

mfb
Mentor
A red apple is a type of red object.
"Red" is a properly of a red apple.

Ignore that there are apples of different color, for this analogy apples are always red.

Oh wow...I feel so stupid. Thanks a lot for the clarification !

A red apple is a type of red object.
"Red" is a properly of a red apple.
But "red" and "red object" are different things, so I don't get this analogy... "Red" is a property, but "red object" is not.

mfb
Mentor
No analogy is perfect.
You can also say "Is a red object" is a property of a red apple, if you want to have the object in both sentences.

Khashishi
Energy may be a property of matter, but it's a property of radiation, too! As the universe expanded, the energy density of radiation has decreased by (linear scale)^4, while the energy density of matter as decreased by (linear scale)^3, so in the early universe, the radiation energy density was much higher than the matter density. So you could say, in a way, radiation preceded matter. But you'd better know the details.

I think matter technically refers to massive things composed of fundamental fermions, like electrons and quarks, and the forces that hold them together. Radiation usually refers to light and also matter moving at relativistic speeds. (At relativistic speeds, most of the energy is in kinetic energy, whereas in ordinary matter, most energy is in rest mass.)

timmdeeg
Gold Member
(At relativistic speeds, most of the energy is in kinetic energy, whereas in ordinary matter, most energy is in rest mass.)
With most of the rest mass of the hadrons originating from binding energy however.

https://en.wikipedia.org/wiki/Quark