What came first, matter or energy?

[Aaron1947]

I don't know if this question is even relevant, but I wonder about it so I'm asking it.

I understand from GR that matter and energy are essentially interchangeable, that matter can be converted to energy and vice versa.

I also understand that the earliest "snapshot" of our cosmos (via the background radiation) was a plasma of matter and energy. But, if I understand everyone correctly, we predict that this plasma came from the annihilation of matter and antimatter. So we began with matter and antimatter, then that was converted into a plasmic mixture of matter and radiation.

So am I correct in saying that energy came from matter?

 

[Drakkith]

The plasma was composed of matter, antimatter, and radiation, and would have had plenty of energy at the same time. Note that energy is a property of matter and fields, it is not something in and of itself.

 

[Orodruin]

that matter can be converted to energy and vice versa.

Energy is a property of matter, just like momentum. Like other energy forms, such as kinetic and potential energy, mass energy can be converted into other forms of energy. You cannot convert mass to "pure energy", there is no such thing.

 

[rootone]

'Matter' in the usual sense of the word means stuff made of atoms.
The first atoms were hydrogen and helium, probably a small amount of lithium.
These atoms could not exist until the original hot plasma Universe had cooled (and expanded) considerably.
https://en.wikipedia.org/wiki/Big_Bang_nucleosynthesis

 

[Aaron1947]

So in reality, energy is just matter in another form? And there can be no energy without matter first?

 

[weirdoguy]

So in reality, energy is just matter in another form?

Read this again:

Energy is a property of matter, just like momentum.

 

[Aaron1947]

Read this again:

Okay, now I get it.

 

[momo666]

I have a question on this topic if it's not too much. I heard something about converting kinetic energy to matter and that this is done in the LHC. How can this be?

 

[jbriggs444]

I have a question on this topic if it's not too much. I heard something about converting kinetic energy to matter and that this is done in the LHC. How can this be?

You start with particles with small rest masses but large kinetic energies relative to their combined center of mass. You end with a shower of particles with a larger total of the individual rest masses but smaller total of the kinetic energies.

Energy is conserved. But "total rest mass of the individual particles" is not a conserved quantity.

 

[Chronos]

Under inflationary cosmology the universe was initially composed entirely of energy [the inflaton field], which subsequently 'decayed' into matter. Under traditional big bang cosmolgy, the universe may have initially included some form of matter, however most, if not all, matter in the universe that emerged from inflation 'decayed' out of the inflaton field. Since matter and energy are equivalent under GR, the distinction is largely moot.

 

[Orodruin]

Under inflationary cosmology the universe was initially composed entirely of energy [the inflaton field]

I would not call this "entirely energy" or "pure energy" as it is a very common misconception that something called "pure energy" exists. The inflaton field is a field which also has energy as a property - just like the electromagnetic field and matter does.

 

[Chronos]

Agreed, I'd being will to substitute the term devoid of matter for energy. I'm glad you raised the point because definiing matter and energy is not nearly as neat and clean as is typically imprinted upon laymen [IMO].

 

[momo666]

Under inflationary cosmology the universe was initially composed entirely of energy [the inflaton field], which subsequently 'decayed' into matter. Under traditional big bang cosmolgy, the universe may have initially included some form of matter, however most, if not all, matter in the universe that emerged from inflation 'decayed' out of the inflaton field. Since matter and energy are equivalent under GR, the distinction is largely moot.

What is this field made of? I am having a hard time finding out this answer. From what I get a field is something that has energy in every point of space but what exactly "holds it together" ? What makes it to be a structure and not just a bunch of points of energy?

 

[Orodruin]

What is this field made of?

This is a moot question, it has no answer. A field is a basic part of the model, eg, the electromagnetic and gravitational fields. They are not "made of" something else, they are the basic enteties of the model.

From what I get a field is something that has energy in every point

No, a field is something that has a value at every point. Then energy (or rather, energy density) can be associated to the field configuration, ie, what values the field takes.

 

[Chronos]

See http://plato.stanford.edu/entries/quantum-field-theory/ for further discussion.

 

[momo666]

This is a moot question, it has no answer. A field is a basic part of the model, eg, the electromagnetic and gravitational fields. They are not "made of" something else, they are the basic enteties of the model.

I think I am missing something here. From what I understand, you sound as if fields have no description. Are you saying that fields are the fundamental building block and therefore cannot be divided further?
Are they like an assumed axiom that cannot be proved but by assuming it exists, it answers some questions?

P.S. Chronos, your link does not seem to work. Is it just me or it's broken ?

 

[Chronos]

Link repaired. Just for clarification a field has potential energy at every point, it requires some kind of interaction for that potential to be realized.

 

[rootone]

The link works OK for me, won't be able to read it til tomorrow though.
edit:. Ah I see now that it had been updated.

Yes I think it's fair to say that a lot of theories start from the proposition that if X is true then Y should be true, where Y is something tangeable that can be measured.

 

[mfb]

Are they like an assumed axiom that cannot be proved but by assuming it exists, it answers some questions?

Physics cannot prove anything. Physics makes models based on observations and compares the predictions of those models to more observations. The model of fields as fundamental concept works extremely well.

 

[momo666]

Physics cannot prove anything. Physics makes models based on observations and compares the predictions of those models to more observations. The model of fields as fundamental concept works extremely well.

Yes, my bad. Logic proves, science demonstrates. So was I right in saying that fields are similar to axioms ? They are assumed and because that assumption gives us results, we suppose that assumption is right?

 

[mfb]

We don't assume it is right, we don't care about "right" in physics - that is philosophy.

 

[Orodruin]

We don't assume it is right, we don't care about "right" in physics - that is philosophy.

To elaborate on this: Physics is an empirical science. It does not care about whether or not something is fundamentally correct or what really "is". The only thing that is important (ideally) is whether or not your theory makes testable predictions that agree with measurements. If it does, then it is a useful theory. If it does not, it might still be a useful approximation in some restricted domain of validity (such as Newton's theory of gravity restricted to relatively light bodies moving at velocities much smaller than the speed of light).

 

[momo666]

I have another question If that is okay. This Wiki article is confusing : https://en.wikipedia.org/wiki/Matter

Specifically: “special relativity shows that matter may disappear by conversion into energy, even inside closed systems, and it can also be created from energy, within such systems. However, because mass (like energy) can neither be created nor destroyed, the quantity of mass and the quantity of energy remain the same during a transformation of matter (which represents a certain amount of energy) into non-material (i.e., non-matter) energy. This is also true in the reverse transformation of energy into matter.”

 

[Drakkith]

I have another question If that is okay.

Sure. What exactly is your question?

 

[momo666]

Well it makes it sound like energy is converted into matter but I'm confused since everyone says energy is a property of matter.
"special relativity shows that matter may disappear by conversion into energy, even inside closed systems, and it can also be created from energy"
"during a transformation of matter (which represents a certain amount of energy) into non-material (i.e., non-matter) energy."
"This is also true in the reverse transformation of energy into matter.”

So what exactly it's taking place here? Does this happen in nature or just in experiments?

 

[mfb]

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

 

[momo666]

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]

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]

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.

 

[momo666]

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]

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.

 

[momo666]

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

 

[weirdoguy]

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]

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.)