Mass= energy,how we know this.

[Sorcerer]

Einstein's 1905 paper in which he derives E=mc²does not mention matter at all, and says "The mass of a body is a measure of its energy-content" (nor does he use "matter" in this context in the original SR paper)

In physics, a physical body or physical object (sometimes simply called a body or object) is an identifiable collection of matter, which may be more or less constrained to move together by translation or rotation, in 3-dimensional space.

 

In physics, a physical body or physical object (sometimes simply called a body or object)

 

 

And where does that say "matter [or a body] is energy"?

 

And in what way is energy "an identifiable collection of matter, which may be more or less constrained to move together by translation or rotation, in 3-dimensional space"?

 

, which may be more or less constrained to move together by translation or rotation, in 3-dimensional space.

 

I'd have to go back through the comments to find the how the argument progressed. Just pointing out that he does mention matter, he just doesn't use the direct word.

Edited August 3, 2015 by Sorcerer

[swansont]

If we're doing semantics, what else are bodies composed of?

 

 

Still doesn't answer the question.

I'd have to go back through the comments to find the how the argument progressed. Just pointing out that he does mention matter, he just doesn't use the direct word.

 

He says the mass of a body, not the body itself, and there were quotation marks around what was posted, implying it was a direct quote.

[studiot]

There is not a human that has never mis-spoke.

 

So surely in a Science forum we should not spend lots of time and effort on rehashing who said what?

 

But rather discuss the best available knowledge of the theory.

[Sorcerer]

 

Still doesn't answer the question.

 

He says the mass of a body, not the body itself, and you had quotation marks around what you posted, implying it was a direct quote. If it wasn't, then how about just admitting that, rather than all this tap-dancing?

lol, I just googled "body definition physics" and cut and paste, quotes and all. And I didn't read the rest of the thread.

 

Yes, mass is just another form of energy.

 

I think the picking over equivalence and equals is a bit pointless.

 

But still when I think of electron positron pair production, the photons energy lends its mass to the particle pair, where does the rest of the electron and positron come from? (I know some decays produce other particles, but as far as I know, 1 photon near a nucleus is enough to create matter). If energy can produce matter in this way, surely there is no harm in saying that not only is the mass and energy equivalent, but there is a very close relationship between the two kinds of particles, enough to place them all in a group together. And not a huge stretch from there to say that matter is a form of energy and vice a versa.

Yes yes I know, Energy is a property of matter..... but energy is also a property of energy lol, all bosons have energy, they're not simply just energy, or are they?

 

Neutrinos have mass, models wrong, all discussions pointless.

Edited August 3, 2015 by Sorcerer

[MigL]

Can you guys go back and re-read AJB's post #2.

Energy, and mass, are a number we associate with, or a property of, a particular arrangement, or state, of particles and fields.

And matter IS those particles and fields.

Edited August 3, 2015 by MigL

[Sorcerer]

Can you guys go back and re-read AJB's post #2.

Energy, and mass, are a number we associate with, or a property of, a particular arrangement, or state, of particles and fields.

And matter IS those particles and fields.

Since a photon is an "arrangement, or state, of particles and fields", which has a number associated with it for Mass (0) and energy, would you call a photon matter?

 

What about a Gluon? Or the theoretical graviton? All of these bosons have (or are meant to have) 0 mass. I can understand the other bosons being grouped with Matter since they have mass, but I would group massless particles/fields under Energy, not Matter.

 

Photons stand out especially since they are the carrier of the electromagnetic field, and they only have a value for Energy associated with them. Therefore they are just Energy. If 2 gamarays with E but no M can produce a e⁺ e^- pair which then has both M and E, and particles which have M + E are matter, while particles with only E and no M are Energy, then Energy can create Matter.

Matter is made of energy is not the way to think of it. Energy is a property of a physical configuration; it is basically some number we can associate with a given arrangement of particles and fields.

 

Again I would ask, do you include the photon as matter then?

 

Is the word, matter arbitrary when the massless particles are included because it is then all inclusive and makes no distinction between anything?

 

Is misleading to say a photon IS energy, but rather it should be said it HAS energy?

 

Could it be said that these particles have none of their energy total tied up in mass (γ · g and the graviton,) but the rest include their mass as a part of their energy total?

 

 

(About the Higgs, energy and mass)

Does this mean that mass is just the part of the energy total which associates with the Higgs field? IE in the particular configurations of energy found in the particles with mass, part of that energy is tied up with interactions with the higgs field, and this we measure as mass, while there is also various ammounts of non-mass energy (energy) associated with each particle.

 

How does E=mc² relate or fit in with models of the Higgs field?

[ajb]

Again I would ask, do you include the photon as matter then?

Photons are not considered matter. The general distinction for fundamental particles is that 'matter' = fermions and 'forces' = bosons.

 

Is the word, matter arbitrary when the massless particles are included because it is then all inclusive and makes no distinction between anything?

See above.

 

Is misleading to say a photon IS energy, but rather it should be said it HAS energy?

Exactly, a photons have a property we call energy.

 

Could it be said that these particles have none of their energy total tied up in mass (γ · g and the graviton,) but the rest include their mass as a part of their energy total?

Yes, that sounds okay.

 

Does this mean that mass is just the part of the energy total which associates with the Higgs field? IE in the particular configurations of energy found in the particles with mass, part of that energy is tied up with interactions with the higgs field, and this we measure as mass, while there is also various ammounts of non-mass energy (energy) associated with each particle.

In the broken phase the Higgs gives mass terms in the Lagrangian of the standard model. This is associated with a non-zero vacuum expectation value of the Higgs field; so you may be able to interpret it like this. I must also add that the mass of composite particles is mostly due to their binding energy and not the Higgs.

Edited August 4, 2015 by ajb

[Sorcerer]

Photons are not considered matter. The general distinction for fundamental particles is that 'matter' = fermions and 'forces' = bosons

Why are the W and Z bosons which have mass, but are also force carriers not considered matter? Do these show some duality?

 

What about the composite bosons? They're made from "matter" and are included under bosons not for their force carrying property but for their spin.

• Any meson, since mesons contain one quark and one antiquark.
• The nucleus of a carbon-12 atom, which contains 6 protons and 6 neutrons.
• The helium-4 atom, consisting of 2 protons, 2 neutrons and 2 electrons.

 

Exactly, a photons have a property we call energy.

 

 

Apart from energy, what other properties do photons have?

 

Where do these properties go or what do they transform into during electron/positron pair production?

 

The energy of the photons goes to both energy and mass. Does this energy create any other properties?

What portion of the energy creates the positive and negative charges?

 

Or are these a creation of the opposing split of the charged particles, eg +1-1=0 photons have 0 charge. (Doesn't this suggest there is some kind of fleeting particle intermediary which has 0 charge and consists of the energy and mass equivalent to the positron and the electron = Energy of the 2 photons?)

Edited August 4, 2015 by Sorcerer

[ajb]

I thought photons were bosons, they carry the electromagnetic force, gauge bosons, here you equate matter with bosons, yet not with photons?

 

Fundamental particles that are called 'matter' are fermions; so charged leptons (neutrinos are a odd ball here, but I guess they should be called 'matter') and quarks.

 

The 'forces', so gauge bosons are bosons. So light is a 'force'.

 

I use the terms very loosely here, but this is the standard distinction.

 

Why are gluons considered matter and photons not?

Gluons are not usually considered as matter. You can however have bound states of gluons called glueballs!

 

Gluons have no mass like the photon and are also vector and gauge bosons, what makes the photon more special/different?

Nothing.

 

 

Apart from energy, what other properties do photons have?

Spin.

 

Where do these properties go or what do they transform into during electron/positron pair production?

We have several conservation laws in the standard model such as lepton and baryon number.

 

The energy of the photons goes to both energy and mass. Does this energy create any other properties?

The particles produces can have any allowed properties provided the conservation laws are respected.

 

What portion of the energy creates the positive and negative charges? Or are these a creation of the opposing split of the charged particles, eg +1-1=0 photons have 0 charge. (Doesn't this suggest there is some kind of fleeting particle intermediary which has 0 charge and consists of the energy and mass equivalent to the positron and the electron, and also the 2 photons?)

I don't quite follow this. Again, everything is allowed as long as the conservation laws are respected.

Edited August 4, 2015 by ajb

[Sorcerer]

Sorry, I misread your first part before and made a wrong reply I edited it, but you mustve replied while I was typing.

Quote

Photons are not considered matter. The general distinction for fundamental particles is that 'matter' = fermions and 'forces' = bosons

Why are the W and Z bosons which have mass, but are also force carriers not considered matter? Do these show some duality?

What about the composite bosons? They're made from "matter" and are included under bosons not for their force carrying property but for their spin.

• Any meson, since mesons contain one quark and one antiquark.
• The nucleus of a carbon-12 atom, which contains 6 protons and 6 neutrons.
• The helium-4 atom, consisting of 2 protons, 2 neutrons and 2 electrons.
  

That's it ammended.

 

I don't quite follow this. Again, everything is allowed as long as the conservation laws are respected.

Ok, let me rephrase: when 2 photons combine in electron/positron pair production, what is the mechanism by which their properties create the postive charge of the positron and the negative charge of the electron?

Since photons only contribute energy and spin, how are the +/- charges formed?

Do the photons combine to an intermediary particle which is a precusor of the e+ e- pair with a neutral charge?

When this precursor splits, is the neutral charge split into it's constituent charges?

 

IE photon (0 charge) + photon (0 charge) ------> intermediary/precursor (charge 0) --------> e+ (+e) , e- (-e) ( Precursor 0 = +e-e )

[swansont]

 

Ok, let me rephrase: when 2 photons combine in electron/positron pair production

 

Only one photon is involved.

 

Since e- and e+ have opposite charge it add to zero; no net charge is created.

[Sorcerer]

It is interesting that while photons combine for pair production, after pair production they again are needed for carrying the electromagnetic force of the 2 charged particles.

Are these force carriers and their energy derived from the original photons?

Are they an internal part of the electron and positron?

Or are the photons which carry these forces borrowed from the surrounding system, is there something "virtual" about these photons themselves?
If so, is their virtual nature balanced by the opposing charges of the pair, so they are opposite and equal and don't violate any conservation laws?

 

Only one photon is involved.

 

Since e- and e+ have opposite charge it add to zero; no net charge is created.

 

Thanks my source is wiki, it was wrong, it has been updated. iirc it said that 2 photons were needed for the production of the virtual pair near a nucleus. And it needs to be there to conserve momentum.

The photon must be near a nucleus in order to satisfy conservation of momentum, as a photon pair producing in free space cannot both satisfy conservation of energy and momentum.

The photon must be near a nucleus in order to satisfy conservation of momentum, as a photon pair producing in free space cannot both satisfy conservation of energy and momentum.

 

[ajb]

Why are the W and Z bosons which have mass, but are also force carriers not considered matter?

They are fundamental bosons and so are not considered as matter. Loosley, they do not form part of the (naive) model of atoms or nuclei.

 

What about the composite bosons? They're made from "matter" and are included under bosons not for their force carrying property but for their spin.

Composite bosons and fermions are different. The distinction between 'matter' and 'forces' is only for fundamental particles.

 

...what is the mechanism by which their properties create the postive charge of the positron and the negative charge of the electron?

Such mechanism are part of quantum electrodynamics. You can look at the allowed Feynman diagrams to get a picture of what is happening. The key point is we have lots of conservation laws and creating '+' and '-' from '0' is okay (provided no other conservation laws are broken).

[swansont]

 

Thanks my source is wiki, it was wrong, it has been updated. iirc it said that 2 photons were needed for the production of the virtual pair near a nucleus. And it needs to be there to conserve momentum.

 

The photon must be near a nucleus in order to satisfy conservation of momentum, as a photon pair producing in free space cannot both satisfy conservation of energy and momentum.

 

 

Yes, "the photon", i.e. one. If you could do this with two photons, you would not need the nucleus to conserve momentum.

 

Such mechanism are part of quantum electrodynamics. You can look at the allowed Feynman diagrams to get a picture of what is happening. The key point is we have lots of conservation laws and creating '+' and '-' from '0' is okay (provided no other conservation laws are broken).

 

IOW, "Everything not forbidden is compulsory" (M. Gell-Mann)

[ajb]

Or are the photons which carry these forces borrowed from the surrounding system, is there something "virtual" about these photons themselves?

If so, is their virtual nature balanced by the opposing charges of the pair, so they are opposite and equal and don't violate any conservation laws?

By virtual we mean that they never appear as the external legs of a Feynman diagram, they are not directly observable and do not have to obey the usual rules that external particles do. There is no violation of any conservation laws 'externally'.

 

IOW, "Everything [/size]not forbidden is compulsory" (M. Gell-Mann)

Indeed, even if the channel is exponentially suppressed!

Edited August 4, 2015 by ajb

[MigL]

Maybe I'm wrong, but I get the impression that you think elementary particles ( bosons and fermions ) are aggregate particles, of which a portion is the energy, another portion is the mass, yet another portion is the charge, etc.

 

A better way to think of these particles is as a manifestation of their respective fields.

For example, the photon is not a particle with energy and mass, but rather, a manifestation of the EM field which has a certain energy and the properties of this field constrain it to move at c . At this 'speed', it has a momentum and therefore 'effective' mass. It, however, has no 'rest' mass, as it can never be at rest.

The electron as another example, is a manifestation of the electron field, and it again has a certain energy. This field is allowed to interact with the Higgs field. producing mass for fermions.

Some bosons, the w and z particles are such, are also allowed this interaction with the Higgs field, and as a result also aquire mass.

[Asimov]

Migl: Thanks for your imput.I dont know whom you were addressing. You are correct about viewing particles as manisfestations of their fields but I dont see the relevance to my original post, the Ferris thought experiment that seems to be overlooked!

 

This thread has drifted as so often they do but everyone learns as we go. I will summarize my thoughts.

 

My references to Einsteins4+papers was to document E=M which states without need for footnotes that E is M. Units dont matter. Sorry if some dont get this most fundamental of relativitiy's tenets.

 

In summary, my opinions.

 

E=M literaly means E=M. Believe otherwise as you wish. Math wont disprove this basic fact. Hard to visualize though.

 

Energy is the ability to do work. To do something. Change things. Many manistfestations. Fundamentally we know its manisfestations. How it makes thing behave No one knows what it is. Everything corporeal in this universe is some form of it. If anyone knows fundamentally what it is, please invite me to your Nobel ceremony.

 

Energy is conserved----- Never changed to, converted to or sorta made into anything other than another form of energy. Ever. Nada. There is energy, and mass must be energy. Unequivocally! Same, not sorta like. Mass is not made of energy. It IS energy. End of story. Conservation of energy, many many sources. Sacred tenet as it were.

 

Matter is many fields manisfesting as well, matter. OK, so? Energy goes a long way

 

Irest my case and members hav clarified and sollidified my interpretations. Thank you and see you in other threads..

 

T o make me feel better I was told I am sorta right but physicists dont think of it this way. I now consider that a compliment..Feel better already.

[MigL]

Sorry, I was addressing Sorcerer.

And yes, we have wondered a bit off the topic of the OP.

[swansont]

 

My references to Einsteins4+papers was to document E=M which states without need for footnotes that E is M.

 

I still don't know which 4 papers these are.

 

"The mass of a body is a measure of its energy-content" is not the same as ""The mass of a body is its energy-content". The former being a quote from Einstein's E=mc^2 paper, and the latter being what you are claiming he said.

[Strange]

My references to Einsteins4+papers was to document E=M which states without need for footnotes that E is M. Units dont matter.

 

Units don't matter? So 5 pints is the same as 5 miles?

 

 

Sorry if some dont get this most fundamental of relativitiy's tenets.

 

You are the one who doesn't seem to get it.

[jajrussel]

I find this to be an interesting discussion, though I am not sure of the exactness of the disagreements. E=MC^2 makes a statement, so does E=M. They are not the same statement. As a newbie, and a slow learner certain things tend to confuse me, and the inexactness, or incompletion of a statement can be as confusing as having no idea at all on a subject. I have read that E=MC^2 is a relative term, and that it is a term of proportion. My understanding is that it is a kinetic statement. E=M seems incomplete, simply because something can have energy, yet 0 mass.

 

I have always found this strange, but not entirely unbelievable so long as they stick to the rule. So the statement E=M does not exactly stick to the rule. It implies that anything that has energy has mass, yet ask if a photon has mass, and the answers tend to get really slippery. Does a photon have energy? Yes. Does it have mass? Either no, or it has no rest mass. I thought mass was a kinetic relationship so perhaps at c it has mass, but at rest it has o mass? Well, no, that's the wrong way to think about it, a photon is never at rest it can not be at rest. But, my understanding is that nothing ever stops moving? Well, yes that is true, but when things are at rest their energy and mass at rest are said to be equivalent. Slippery, slippery, slippery.

 

So you apparently need to add something the equation E=M that shows them both to be at rest in order to complete the statement, making it true.

 

And according to Wikipedia E=MC^2 does just that.

 

Again, slippery, slippery, slippery.

Edited September 6, 2015 by jajrussel

[Sensei]

[math]E=m_0*c^2*\gamma[/math]

m₀ is rest mass.

 

[math]m=m_0*\gamma[/math]

m is relativistic mass.

 

So when somebody writes:

[math]E=m*c^2[/math]

It can also mean the same as the first equation, depending on interpretation of m.

 

where gamma is:

[math]\gamma=\frac{1}{\sqrt{1-\frac{v^2}{c^2}}}[/math]

 

When v=0, [math]\gamma=1[/math] (the same frame of reference as we are)

The first equation simplifies to:

[math]E=m_0*c^2[/math]

Edited September 7, 2015 by Sensei

[Asimov]

Jajrussel:Thank you for your input. I too am not sure of the exactness of the disagreement. I intended nothing profound or new. I offered Calder's thought experiment as a means of visualizing energy-mass equivalence. Really basic stuff. From Calder: At 1/10 C the energy of light of an approaching star is enhanced by 10.55% while receding the star loses 9.55% of its energy.. There is an average gain of .5 of one percent in the energy emitted by the star as seen by someone seeing it speeding past him at 1/10 C ! This means that the energy emitted by a star depends on the observer and how fast he is moving in relation to the star.This naturally leads physicists to the most fundamental result of relativity. Energy is mass and visa versa. Not sorta, or in some contexts, or can be converted one to the other etc.. Equivalent, period. This most basic concept is hard to visualize. Some dont seem to accept it but it is vital to understanding relativity.

You probably know this but physicists do take a little license with words.If they say a photon has energy but not mass they mean no rest mass. The energy-mass is relativistic mass due to its motion. At rest a photon doesnt exhist. Anything without mass-energy is only a concept.

[Strange]

I too am not sure of the exactness of the disagreement.

 

Maybe that is the problem. You don't seem to know what you are talking about. For example:

 

Energy is mass and visa versa.

 

Again: NO. NO. NO.

 

Equivalent

 

Yes.

 

This most basic concept is hard to visualize.

 

You do seem to be struggling with it.

[Asimov]

Strange; This is not some new radical perspective I am illustrating with the Calder scenerio. It is compelling thoughts like it that lead physicists to mass- energy equvalence. At least give Calder's thoughts some reflection. Notice when Einstein or any noted physicist states mass-energy equivalence they don mince words such as "somewhat equivalent" or "analogous to" etc. Or "equivalent to in some ways.". Equivalent. Yes. Period. In the words of Bob Dylan, dont critisize what you cant understand. I dont and do appreciate all input. This beats drinking beer at the beach doesnt it?