Is mass a property of matter?

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I searched through previous posts, but did not see this question posted - but I was wondering if mass and matter are different entities. I was reading a book that said something to the effect "if this entire paper clip was converted to energy using E=mc2".... but can a proton (what I see as matter) can be transformed into energy. I'm thinking it's the mass contained in the protons, neutrons, etc, that is being converted into energy.

Regarding the nuclei of atoms, I see the ability of the particles within the nucleus the to hold onto a separate entity called mass, changes from atom to atom (eg, a H nucleus - a single proton, has the ability to hold onto more mass as the individual protons in He). Can someone explain in simple terms where I'm going off track? Thanks.
 

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  • #2
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The mass of the nucleus is not the simple sum of proton and neutron masses. It varies depending on the element. Hydrogen and uranium have the "heaviest" protons. Some of the strong force energy (where most of the mass comes from) gets shared differently depending on how many nucleons you're binding.
 
  • #3
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I was wondering if mass and matter are different entities
Mass and matter are different. Matter has mass. Matter also has other properties besides mass.
 
  • #4
lekh2003
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I'm very sure this question has been asked previously, I can't find it though, just like you.
 
  • #5
Mister T
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I searched through previous posts, but did not see this question posted - but I was wondering if mass and matter are different entities.
Yes, of course they are! Matter is something that we encounter in Nature, mass is a property we invented in an attempt to understand the way matter behaves.

I was reading a book that said something to the effect "if this entire paper clip was converted to energy using E=mc2".... but can a proton (what I see as matter) can be transformed into energy.
If a proton collides with an anti-proton they will both annihilate.

I'm thinking it's the mass contained in the protons, neutrons, etc, that is being converted into energy.
Mass is a property of these particles, it doesn't make sense to me to think of mass as being contained in the particles.

It's more straight forward to consider an elementary particle such as an electron. If you have an electron and a positron colliding, they can annihilate and produce two photons. Some people will say that the mass of the electron is converted to energy, but in fact the mass of the electron-positron pair is equal to the mass of the photon pair. Likewise the energy of the electron-positron pair is equal to the energy of the photon pair. And the energy is equivalent to the mass, so it's perfectly valid to say that the mass of the electron-positron pair is equal to the energy of the photon pair, leading some authors to claim that mass is converted to energy. That is essentially what that author meant by the paper clip example.

You could just hit the paper clip with a hammer and say the mass it had before is equal to the energy it has after, but I don't think anyone would think of that as a conversion of mass to energy.

Most of this confusion comes about because the mass-energy equivalence demonstrates that mass is not a measure of the quantity of matter, and it's hard for a lot pf people to really grasp that.
 
  • #6
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Mass and matter are different. Matter has mass. Matter also has other properties besides mass.
Would you consider mass and matter as separate entities?

If a proton collides with an anti-proton they will both annihilate.
I did a little more digging and read an article about the big bang and the higgs field. I'm not sure it was correct, but it said that in the first few moments of the big bang, matter did not have mass. Because it's the big bang, all bets are probably off, but If the massless proton met up with the massless anti-proton I would think they would annihilate, but do you think any energy would result?

Thanks
 
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Would you consider mass and matter as separate entities?
I wouldn't consider mass to be an entity at all. It is like asking if I would consider colors and cars as separate entities. Cars have color, but cars and colors are not the same thing and color isn’t an entity.
 
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davenn
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Hydrogen and uranium have the "heaviest" protons
Where on earth did you get that info from ?
you had better revise that, it is very wrong
All protons have the same mass = 1.673 × 10-27
 
  • #9
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True. All protons that are isolated from a nucleus are identical in every way. When they are bound together with other protons and neutrons, however, their masses don't simply add up. It's as if they have different effective mass depending on the element. It is analogous in layman's terms to protons being "heavier" in some configurations than others when we view energy and mass as essentially the same thing.
 
  • #10
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All protons that are isolated from a nucleus are identical in every way.
No, all protons everywhere are identical.
When they are bound together with other protons and neutrons, however, their masses don't simply add up.
That is correct, but it is not a property of the protons.
It's as if they have different effective mass depending on the element.
That is a very misleading description.

Oh by the way: The stable helium and lithium isotopes have a lower binding energy than uranium.
 
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  • #11
kimbyd
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True. All protons that are isolated from a nucleus are identical in every way. When they are bound together with other protons and neutrons, however, their masses don't simply add up. It's as if they have different effective mass depending on the element. It is analogous in layman's terms to protons being "heavier" in some configurations than others when we view energy and mass as essentially the same thing.
Typically the way this is described is rather different: the mass of a nucleus (whether Uranium or Hydrogen) is the sums of the masses of the individual nucleons minus the binding energies between them.

For example, the mass of a U238 isotope is 238.05078826u.

Each proton has a mass of 1.007276u.
Each neutron has a mass of 1.008665u.

U238 has 146 neutrons and 92 protons. The sums of those masses is 239.934u. Thus, the U238 isotope has a binding energy of about 1.9u. The mass of the U238 nucleus is lower than that of the components because if it were higher, then the nucleus would decay rapidly into lower-energy states.
 
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  • #12
Mister T
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When they are bound together with other protons and neutrons, however, their masses don't simply add up. It's as if they have different effective mass depending on the element.
Only if one wishes to cling to the notion that the sum of the masses of the constituent particles equals the mass of a composite body. Such a notion has been demonstrated experimentally to be false for reasons that are well-understood and fully explained by Einstein's mass-energy equivalence.
 
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  • #13
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mass is not a measure of the quantity of matter
I think that I am beginning to see this and I am trying to develop a better sense of what is happening with the relationship between matter and mass and at the same time, get a better understanding of what mass is. I start to think that mass is not a property of matter, and that matter is a completely separate entity which somehow takes on mass (from the higgs field). (please pardon my confusions as I try to grasp what is going on)

To get a better understanding, I asked Mr. T a question regarding his post

If you have an electron and a positron colliding, they can annihilate and produce two photons. Some people will say that the mass of the electron is converted to energy, but in fact the mass of the electron-positron pair is equal to the mass of the photon pair
In the early moments when the universe began, before particles had mass, if an electron met a positron, I would see them as annihilating each other, but because there is no mass, would any photons result? Or, can photons result only if mass is present?
 
  • #14
davenn
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I start to think that mass is not a property of matter, and that matter is a completely separate entity which somehow takes on mass (from the higgs field). (please pardon my confusions as I try to grasp what is going on)
Did you not read Dale's comment in post #3 ? .... it gave you the answer to the incorrect statement above :smile:
 
  • #15
Mister T
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I start to think that mass is not a property of matter,
I'm not sure what you want. This question has been asked and answered. Mass is a property of matter.

Elaborating a bit, if we have two pieces of matter we have established the process you'd use to compare their masses. Humans didn't invent matter. Humans invented the concept of mass, of if you prefer, discovered a means for comparing the masses of pieces of matter.

In the early moments when the universe began, before particles had mass, if an electron met a positron, I would see them as annihilating each other, but because there is no mass, would any photons result?
I don't know an answer to this question.
 
  • #16
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In the early moments when the universe began, before particles had mass, if an electron met a positron, I would see them as annihilating each other, but because there is no mass, would any photons result? Or, can photons result only if mass is present?
They still had energy. "Photons" is a complicated topic before electroweak symmetry breaking.
 
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