# What Is Mass?

mass

141 replies to this topic

### #1 antoine

antoine

• Members
• 92 posts

Posted 29 July 2017 - 05:25 PM

I have heard the term mass mentioned several times, but when i ask what is mass, nobody seems to know the answer, do you know?

### #2 Turtle

Turtle

Member

• Members
• 15445 posts

Posted 29 July 2017 - 10:21 PM

### #3 exchemist

exchemist

Creating

• Members
• 1641 posts

Posted 30 July 2017 - 03:16 AM

Turtle I think you are being a bit unfair, actually. It seems to me that, though we all think we know what mass is, and we use it all the time, describing it is not wholly straightforward. (By the way, the same is true of energy, it seems to me.)  I think it is a topic worth a discussion.

For a start, there seems to be a distinction to be made between what we call "inertial mass" and "gravitational mass". Inertial mass I suppose can be defined as the expression in physics of what people rather loosely call "inertia", i.e. the quantity that determines how much acceleration of a body results from applying a certain force to it. In other words, the "m" in F=ma. You could say this is the "real" definition of mass.

It also turns out that, quite independently of the above, the force of gravitational attraction between two objects is proportional to the masses of them both: F= GmM/r².

Mass of an object is typically thought of as a fixed thing, determined only by the by the number of fundamental particles in the object (protons, neutrons, electrons), as all the fundamental particles have their own characteristic masses. However this is only approximately true, as the energy in a system also contributes to its mass, by E=mc². Thus for example a fully charged battery has a tiny bit more mass than a discharged one. And, more notoriously, the mass of a uranium nucleus is a bit more than that of the sum of its products when it undergoes nuclear fission - hence one way to calculate the energy of an atom bomb.

A cop-out summary of all this is to say that mass is the "m" in all equations of physics containing it!

### #4 Dubbelosix

Dubbelosix

Explaining

• Members
• 760 posts

Posted 30 July 2017 - 04:54 AM

Physicists think of mass as something part of a Mexican hat potential in which a Goldstone-like boson deviates from some ground potential.  That won't mean very much to you and it means very little to any one else.

Mass is a compact form of energy, whereas energy may be considered as a diffused mass.

Mass can be considered also trapped forms of energy or light.

Edited by Dubbelosix, 30 July 2017 - 04:54 AM.

### #5 antoine

antoine

• Members
• 92 posts

Posted 30 July 2017 - 07:49 AM

Turtle I think you are being a bit unfair, actually. It seems to me that, though we all think we know what mass is, and we use it all the time, describing it is not wholly straightforward. (By the way, the same is true of energy, it seems to me.)  I think it is a topic worth a discussion.

For a start, there seems to be a distinction to be made between what we call "inertial mass" and "gravitational mass". Inertial mass I suppose can be defined as the expression in physics of what people rather loosely call "inertia", i.e. the quantity that determines how much acceleration of a body results from applying a certain force to it. In other words, the "m" in F=ma. You could say this is the "real" definition of mass.

It also turns out that, quite independently of the above, the force of gravitational attraction between two objects is proportional to the masses of them both: F= GmM/r².

Mass of an object is typically thought of as a fixed thing, determined only by the by the number of fundamental particles in the object (protons, neutrons, electrons), as all the fundamental particles have their own characteristic masses. However this is only approximately true, as the energy in a system also contributes to its mass, by E=mc². Thus for example a fully charged battery has a tiny bit more mass than a discharged one. And, more notoriously, the mass of a uranium nucleus is a bit more than that of the sum of its products when it undergoes nuclear fission - hence one way to calculate the energy of an atom bomb.

A cop-out summary of all this is to say that mass is the "m" in all equations of physics containing it!

You seem like a reasonable person who understands that mass is not described to an exact process.   You say the mass of an object is typically described as a fixed thing, the properties of an object.  If we were to look at the intrinsic details of atomic structure, seemingly the only force involved in atoms is that of the electron and proton attraction.  Is mass a measurement of this attraction on a bigger scale?

### #6 exchemist

exchemist

Creating

• Members
• 1641 posts

Posted 30 July 2017 - 09:46 AM

You seem like a reasonable person who understands that mass is not described to an exact process.   You say the mass of an object is typically described as a fixed thing, the properties of an object.  If we were to look at the intrinsic details of atomic structure, seemingly the only force involved in atoms is that of the electron and proton attraction.  Is mass a measurement of this attraction on a bigger scale?

You mean the energy of bound states of electrons and nuclei, due to their electrostatic attraction? No. The energy in these atomic bound states is what we see as emitted or absorbed light in spectroscopy but the effect on atomic mass due to E=mc² is minuscule and to all intents and purposes  negligible. For most common purposes you can treat mass as a fixed property of these particles.

Roughly speaking, a proton and a neutron both have a mass of 1 atomic unit* and an electron has a mass  1/1836 of that.

* This tiny unit can be related to normal mass units by considering that a mass of 6.02 x 10²³ protons is one gram.

Best to think of mass first and foremost as "m" in F=ma, i.e. the ratio of the force on an object to the acceleration it produces.

### #7 antoine

antoine

• Members
• 92 posts

Posted 30 July 2017 - 09:54 AM

You mean the energy of bound states of electrons and nuclei, due to their electrostatic attraction? No. The energy in these atomic bound states is what we see as emitted or absorbed light in spectroscopy but the effect on atomic mass due to E=mc² is minuscule and to all intents and purposes  negligible. For most common purposes you can treat mass as a fixed property of these particles.

Roughly speaking, a proton and a neutron both have a mass of 1 atomic unit* and an electron has a mass  1/1836 of that.

* This tiny unit can be related to normal mass units by considering that a mass of 6.02 x 10²³ protons is one gram.

Best to think of mass first and foremost as "m" in F=ma, i.e. the ratio of the force on an object to the acceleration it produces.

I am sorry I am still not getting it,   an atom has mass and charge,   mass is not explained, it is being used just as a word for something we do not know the meaning too.  Charge explains mass?

### #8 Turtle

Turtle

Member

• Members
• 15445 posts

Posted 30 July 2017 - 10:19 AM

Turtle I think you are being a bit unfair, actually. ...

Given the context, I think I am spot on. Let the games begin.

### #9 antoine

antoine

• Members
• 92 posts

Posted 30 July 2017 - 10:29 AM

Given the context, I think I am spot on. Let the games begin.

If you think in someway that I am a troll or playing games then you should be able to explain in detail what mass is ?

You are being a lot unfair., it is a good valued question and good discussion. Gravity and mass have the same characteristics as charge and behave exactly the same way as opposite charges attract.

### #10 Turtle

Turtle

Member

• Members
• 15445 posts

Posted 30 July 2017 - 10:35 AM

If you think in someway that I am a troll or playing games then you should be able to explain in detail what mass is ?

You are being a lot unfair., it is a good valued question and good discussion. Gravity and mass have the same characteristics as charge and behave exactly the same way as opposite charges attract.

Since you seem to know so much about what the answers should be, why are you asking the question?

### #11 antoine

antoine

• Members
• 92 posts

Posted 30 July 2017 - 10:47 AM

Since you seem to know so much about what the answers should be, why are you asking the question?

One mans thoughts and logic does not make certainty.

### #12 exchemist

exchemist

Creating

• Members
• 1641 posts

Posted 30 July 2017 - 10:54 AM

If you think in someway that I am a troll or playing games then you should be able to explain in detail what mass is ?

You are being a lot unfair., it is a good valued question and good discussion. Gravity and mass have the same characteristics as charge and behave exactly the same way as opposite charges attract.

Aha, bonjour Tony C.

"C"= chaussette, n'est ce pas?

### #13 exchemist

exchemist

Creating

• Members
• 1641 posts

Posted 30 July 2017 - 10:54 AM

Given the context, I think I am spot on. Let the games begin.

Yup, you were right. Same disease as on the other forum. Your antennae are clearly more acute than mine.

Edited by exchemist, 30 July 2017 - 10:58 AM.

### #14 antoine

antoine

• Members
• 92 posts

Posted 30 July 2017 - 11:00 AM

Aha, bonjour Tony C.

"C"= chaussette, n'est ce pas?

Il n'est pas difficile d'utiliser un serveur vpn et un nouveau courrier électronique. Je suis un bon scientifique amateur qui est mal compris et qui est interdit sans raison. Je suis un spod comme la plupart d'entre vous, je serai de retour si banni à nouveau. Je demande la pitié de ce forum et, au moins, permettez-moi de publier dans les sections externes, de nouvelles théories et spéculations devraient être tout. Si l'université de Cambridge m'a permis de continuer pendant plusieurs années, pourquoi ne peut-il pas utiliser ce forum?

### #15 exchemist

exchemist

Creating

• Members
• 1641 posts

Posted 30 July 2017 - 12:40 PM

Il n'est pas difficile d'utiliser un serveur vpn et un nouveau courrier électronique. Je suis un bon scientifique amateur qui est mal compris et qui est interdit sans raison. Je suis un spod comme la plupart d'entre vous, je serai de retour si banni à nouveau. Je demande la pitié de ce forum et, au moins, permettez-moi de publier dans les sections externes, de nouvelles théories et spéculations devraient être tout. Si l'université de Cambridge m'a permis de continuer pendant plusieurs années, pourquoi ne peut-il pas utiliser ce forum?

Ah bon? Et vous avez fait quoi exactement a Cambridge? Avec quel resultat?

### #16 antoine

antoine

• Members
• 92 posts

Posted 30 July 2017 - 12:52 PM

Ah bon? Et vous avez fait quoi exactement a Cambridge? Avec quel resultat?

Je pense que votre traducteur goolge ne fonctionne pas correctement, je n'ai rien fait à Cambridge, je suis sur leur forum scientifique, j'y suis allé pendant plusieurs années, sans aucune gêne. Ils obtiennent mon meilleur vote sur le forum scientifique. Cependant, vous voudrez peut-être jeter un oeil à certaines de mes idées. J'ai détruit la dilatation du temps avec une seule logique. Je suis un peu fou et mon libellé peut ne pas être génial, mais je suis assez intelligent.

I think your goolge translator is not working correctly, I did not do anything at Cambridge, I am on their science forum, I have been on there for several years without any bother. They get my top science forum vote. However you may want to have a look at some of my ideas. I have destroyed time dilation with a single piece of logic. I am a bit crazy and my wording may not be great, but I am pretty smart.

Anyway I await to see if I get banned or they will just let me be, I will only post in new theories or alternative if I do not get banned.

Edited by antoine, 30 July 2017 - 12:53 PM.

### #17 exchemist

exchemist

Creating

• Members
• 1641 posts

Posted 30 July 2017 - 01:07 PM

Je pense que votre traducteur goolge ne fonctionne pas correctement, je n'ai rien fait à Cambridge, je suis sur leur forum scientifique, j'y suis allé pendant plusieurs années, sans aucune gêne. Ils obtiennent mon meilleur vote sur le forum scientifique. Cependant, vous voudrez peut-être jeter un oeil à certaines de mes idées. J'ai détruit la dilatation du temps avec une seule logique. Je suis un peu fou et mon libellé peut ne pas être génial, mais je suis assez intelligent.

I think your goolge translator is not working correctly, I did not do anything at Cambridge, I am on their science forum, I have been on there for several years without any bother. They get my top science forum vote. However you may want to have a look at some of my ideas. I have destroyed time dilation with a single piece of logic. I am a bit crazy and my wording may not be great, but I am pretty smart.

Anyway I await to see if I get banned or they will just let me be, I will only post in new theories or alternative if I do not get banned.

Thanks for clarifying. My French is very basic, I'm afraid. I do not use a translator.

If you have ideas, it might be better to advance them, rather than ask apparently innocent questions when in fact you already think you have answers, as that comes across as rather deceitful behaviour. I suggest posting in Alt theories and also avoiding grandiose claims that seem highly improbable, e.g. to have "destroyed" time dilation.

You are another crank, evidently. I doubt I shall be engaging you in much further discussion, but perhaps some others may.

(On the other forum you have no chance, because sockpuppets are forbidden. You have been banned before and that is final I'm afraid.)

Edited by exchemist, 30 July 2017 - 01:09 PM.