Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: paul.fr on 11/05/2007 03:48:01

Title: what is Mass?
Post by: paul.fr on 11/05/2007 03:48:01
all things have mass, but what is mass and can it be manipulated? IE, reduced or increased.
Title: what is Mass?
Post by: another_someone on 11/05/2007 04:19:40
There are at least two answers to that.

Most simply, mass is just a measure of how difficult (how much force is required) to cause an object to change speed or direction - i.e. a measure of just how stubborn an object is going to be about continuing to do what it is doing.

More technically, mass is just another form of energy (E = mc2), and thus can be interchanged with other forms of energy (e.g. in an atomic bomb, where a small decrease in the mass of the bomb releases a huge amount of kinetic energy).
Title: what is Mass?
Post by: lightarrow on 11/05/2007 13:21:44
all things have mass, but what is mass and can it be manipulated? IE, reduced or increased.
You need to loose weight? [;)]
Title: what is Mass?
Post by: another_someone on 11/05/2007 16:34:10
Another technical definition of mass can be a quantum definition, in terms of the wavelength of a quantum wave:

(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fupload.wikimedia.org%2Fmath%2F4%2Fb%2Fb%2F4bb8c7e59b4085b09e450d174e331445.png&hash=ad881da3c8efcdeb459c593429605f7f)

where

Where, at non-relativistic speeds, p = mV

where m = mass, and V = velocity.

Thus the above becomes:

λ = h/mV.

Thus:

m = h/λV

It gets more complex for relativistic speeds, but it still boils down to the mass being a function of the quantum wavelength of the particle.
Title: what is Mass?
Post by: another_someone on 11/05/2007 17:21:34
Most simply, mass is just a measure of how difficult (how much force is required) to cause an object to change speed or direction - i.e. a measure of just how stubborn an object is going to be about continuing to do what it is doing.

OK, leading on from here, I suppose the logical question is to define the object (i.e. matter) and the nature of force.

I suppose, if we go back to the earliest experiments with mass, the experiments that lead us to our most basic understanding of what mass is, it is really about two issues.

The simplest is we weigh objects, which tell us about the relationship between mass and gravity.

Secondly, we observe objects collide - but the objects we see collide are (in the early days) all composed of atoms, and what we are really seeing is the electrons around one group of atoms repelling the electrons around another group of atoms, so the force we see is really an electric force.

Thus, when we look at the relationship between mass when it is weighed, and mass in a collision, we are looking at the relationship between electrical and gravitational forces.

But, even when we are weighing an object, what we are really measuring is a form of of electrostatic collision - since the object whose weight we are measuring is composed of atoms which are repelling other atoms in order to apparently resist the force of gravity.

Thus, all of our modern concepts of mass ultimately derive from a notion of the interaction of electrostatic forces, and the inertia associated with the focii of these electrostatic forces.

We do now have more complicated ideas of subatomic particles that react to strange forces like the strong and the weak force, but these are all attempts to fit more recent observations into these early ideas that were born purely from the observations of electrostatic forces.
Title: what is Mass?
Post by: Batroost on 11/05/2007 19:27:09

What you have pointed out is that the everyday concept of a solid object is flawed. What we precieve as a solid is , as you quite rightly say, merely electrostic repulsion between its atoms and ours.

But I don't think this invalidates our concept of inertial mass. A 'solid' ball of one isotope of lead could be constructed with the same number of atoms as one of a different isotope. The balls would appear physically identical and would certainly have the same number (rougghly!) of electrons and protons - both being lead - so the electrostatic forces between it and us would be the same when we pushed them. But we would be able to percieve/measure the difference in force that would have to be applied in order to give a specific acceleration.
Title: what is Mass?
Post by: another_someone on 11/05/2007 20:25:49

What you have pointed out is that the everyday concept of a solid object is flawed. What we precieve as a solid is , as you quite rightly say, merely electrostic repulsion between its atoms and ours.

But I don't think this invalidates our concept of inertial mass. A 'solid' ball of one isotope of lead could be constructed with the same number of atoms as one of a different isotope. The balls would appear physically identical and would certainly have the same number (rougghly!) of electrons and protons - both being lead - so the electrostatic forces between it and us would be the same when we pushed them. But we would be able to percieve/measure the difference in force that would have to be applied in order to give a specific acceleration.

Not sure that I was trying, as such, to invalidate anything - just to understand the limits of what we perceive and understand.  I was not trying to say that our model is right or wrong (although inherently all models are to some extent wrong, which is why we can so confidently predict that at some time in the future all models will be superceded by a new model).

That different atoms have different masses does not invalidate what I was saying, that our perception of solid matter is only through our perception of electrostatic forces (even the light we see is a manifestation of the electrostatic force).  That the electrostatic force of a the electrons around a lead atom may behave with different inertial characteristics, which we interpret as meaning that they are carrying different amounts of baggage (i.e. have different numbers of neutrons in the atoms) does not alter the fact that this is merely an interpretation of why the electrons are behaving as they are - we cannot actually observe the neutrons (o.k., we cannot actually observe the electrons - only the electric force they exert).
Title: what is Mass?
Post by: Batroost on 11/05/2007 23:30:11
Ok - I see what you mean.

I was tempted to talk about the mass of non-atomic particles - or at least the observed masses calculated from experiment but then most of these experiments involve electromagnetic forces in one way or another.

Perhaps it's worth asking why electromagnetic effects have such a big effect on what we percieve? I think the answer is probably their high strength and long range compared with the other fundamental forces (at least as imagined by physicists):

Strong Force  - Short range  .. but eh the strongest!
Electromagnetic  about 1% as strong as the 'Strong' force but much longer range
Weak Force - 1/1,000,000,000 as strong and very Short range 
Gravitational Force - Long range but very, very weak (10-38 as strong as the stronng force).

So in everday life it is the electromagnetic effects we notice?
Title: what is Mass?
Post by: another_someone on 12/05/2007 00:11:48
Another interesting issue about electrostatic forces, they are the only force that comes in two polarities (i.e. the only force that is able to repel as well as attract).  If there was not this ability to repel, everything in the universe would collapse in on itself (excepting the issue of having to overcome inertia - but there would not be any force able to hold objects apart that have no inertial force pulling them apart).
Title: what is Mass?
Post by: another_someone on 12/05/2007 01:42:45
Strong Force  - Short range  .. but eh the strongest!
Electromagnetic  about 1% as strong as the 'Strong' force but much longer range
Weak Force - 1/1,000,000,000 as strong and very Short range 
Gravitational Force - Long range but very, very weak (10-38 as strong as the stronng force).

The point is that the strong force has a range of less that 10-14 metres, and the weak force has range of about 10-18 metres.  At this distance, we do not even know for sure that the gravitational force exists, and I am not sure that we know how consistently the laws of mass and inertia behave.  So it may even be (although maybe you will say there are experiments to the contrary - I don't know what does exist there) that mass only exists (in the form we understand it) at ranges of greater than the effect of the strong and weak force, and thus mass is only really pertinent to the electrostatic and gravitational forces.
Title: what is Mass?
Post by: jolly on 14/05/2007 01:30:50
More technically, mass is just another form of energy (E = mc2),

Sorry to be annoying but the maths Of E=MC2 is designed to give you the answer for the energy content of an object or whatever- not the mass!!!! To do the equation you need- the mass!
Title: what is Mass?
Post by: another_someone on 14/05/2007 03:42:38
More technically, mass is just another form of energy (E = mc2),

Sorry to be annoying but the maths Of E=MC2 is designed to give you the answer for the energy content of an object or whatever- not the mass!!!! To do the equation you need- the mass!

The point is that the equation provides an equivalence between mass and energy, such that you can create energy by reducing mass (as is done in an atomic bomb) and by inference can create mass from energy - thus the two are interchangeable.
Title: what is Mass?
Post by: jolly on 14/05/2007 14:28:05
More technically, mass is just another form of energy (E = mc2),

Sorry to be annoying but the maths Of E=MC2 is designed to give you the answer for the energy content of an object or whatever- not the mass!!!! To do the equation you need- the mass!

The point is that the equation provides an equivalence between mass and energy, such that you can create energy by reducing mass (as is done in an atomic bomb) and by inference can create mass from energy - thus the two are interchangeable.
More technically, mass is just another form of energy (E = mc2),

Well this is just not true mass is another form of energy!

The equation is E=MC2! right so under that equation mass and energy are considered distint and seperate! to work out the Mass you would have to do the equation

M=E/DIVIDED BY C2

The best bit is really... That you still dont know how to work out the mass or the energy of an object! and until you do you wont be able to check the maths in this equation...

but when you do you will realise it is utterly incorrect!!!
Title: what is Mass?
Post by: Bored chemist on 14/05/2007 15:04:40
Jolly,
If a=b then b=a
you don't need to specify which direction you are going in. If 2 things are the same it doesn't matter if you say this is the same as that or that is the same as this.
Rearanging the equation in terms of mass doesn't change it; it's still Einstein's relation between mass and energy.

And what, exactly do you mean by the last bit
"The best bit is really... That you still dont know how to work out the mass or the energy of an object! and until you do you wont be able to check the maths in this equation...

but when you do you will realise it is utterly incorrect!!!
"?
Title: what is Mass?
Post by: another_someone on 14/05/2007 16:06:48
Well this is just not true mass is another form of energy!

The equation is E=MC2! right so under that equation mass and energy are considered distint and seperate! to work out the Mass you would have to do the equation

M=E/DIVIDED BY C2

Yes, it is correct that m = E/c2.

We have particle accelerators that can impart massive energy to a particle, and observe the increase in mass associated with that – so we know it works.

The best bit is really... That you still dont know how to work out the mass or the energy of an object! and until you do you wont be able to check the maths in this equation...

but when you do you will realise it is utterly incorrect!!!

Mass is merely a quantity that links energy, momentum, and force.

There are many ways of measuring force, energy, and momentum; and so calculate the mass.

I cannot believe you seriously think that we cannot work out how much energy it takes to lift a 1lb weight 1 foot in the air, or how much force your bathroom scales might have upon it when you stand upon it.
Title: what is Mass?
Post by: lightarrow on 15/05/2007 14:00:22
m = h/λV
It gets more complex for relativistic speeds, but it still boils down to the mass being a function of the quantum wavelength of the particle.
For relativistic speeds:
m = Sqrt[1 - (v/c)2]*h/λV
So, if you make the limit for V --> C, m --> 0.
Title: what is Mass?
Post by: jolly on 22/05/2007 11:33:11
Well magnetism and electricity are clearly linked! but I do not agree that mass and energy are! As a mass can hold varying amounts of energy, which flux; so under those circumstances how can you relate them!

Mass I do not believe realitively afects the amount of energy an object can hold!

The problem really is we still dont know what a mass is; or rather we need better understanding of what is classified/constiutues a mass!
Title: what is Mass?
Post by: another_someone on 22/05/2007 16:17:57
Well magnetism and electricity are clearly linked! but I do not agree that mass and energy are! As a mass can hold varying amounts of energy, which flux; so under those circumstances how can you relate them!

Mass I do not believe realitively afects the amount of energy an object can hold!

We are not actually saying that the mass in any way limits the amount of energy matter can hold, but rather the contrary, that the amount of energy a particle contains is manifest in the apparent mass of the particle, and that even at rest, that mass contains some energy.  Neither the mass nor the energy are limited (just as neither electricity nor magnetism limit each other, but they are nonetheless directly linked to each other).


The problem really is we still dont know what a mass is; or rather we need better understanding of what is classified/constiutues a mass!

I don't doubt this, but all that we can talk about is the current state of knowledge based upon experimental results and theories that try to explain those results.  There is no doubt that at some time in the future, new experiments will necessitate a reinterpretation of our understanding of mass, but the problem is that without having performed those experiments (and we don't even know what the experiment is likely to be until we try it, and suddenly find it returns a result not explained by current theory), then we have no basis upon which to make that reinterpretation.  Until that time, we can only work with what we know, not with what we do not know.
Title: what is Mass?
Post by: syhprum on 24/05/2007 09:10:55
My priest says its where we celebrate the Eucharist
Title: what is Mass?
Post by: paul.fr on 24/05/2007 09:42:18
My priest says its where we celebrate the Eucharist

Mass is a place!
Title: what is Mass?
Post by: BenV on 24/05/2007 10:35:50
Well magnetism and electricity are clearly linked! but I do not agree that mass and energy are! As a mass can hold varying amounts of energy, which flux; so under those circumstances how can you relate them!

Mass I do not believe realitively afects the amount of energy an object can hold!

We are not actually saying that the mass in any way limits the amount of energy matter can hold, but rather the contrary, that the amount of energy a particle contains is manifest in the apparent mass of the particle, and that even at rest, that mass contains some energy.  Neither the mass nor the energy are limited (just as neither electricity nor magnetism limit each other, but they are nonetheless directly linked to each other).

Mass and energy are linked by the equation of mass-energy equivalence given in Einstein's theory of special relativity, e=mc2.

Mass is a place!

Wouldn't that be Mass. ?
Title: what is Mass?
Post by: lightarrow on 24/05/2007 21:18:45
An interesting feature of mass is this:
one photon has exactly zero mass.
Two photons, no!
(It's not a joke!).

Edit: two photons have mass if they don't move exactly in the same direction.
Title: what is Mass?
Post by: another_someone on 25/05/2007 01:05:05
An interesting feature of mass is this:
one photon has exactly zero mass.
Two photons, no!
(It's not a joke!).

First I have ever heard about this.  Would you like to say (preferably in words of one, maybe two at most, syllables) how this comes about, and what it means?

Do you mean that two photons that are somehow bound, and it is the binding energy that has mass; or do you mean that even two independent photons are measured to have mass?
Title: what is Mass?
Post by: lightarrow on 25/05/2007 14:20:40
An interesting feature of mass is this:
one photon has exactly zero mass.
Two photons, no!
(It's not a joke!).
First I have ever heard about this.  Would you like to say (preferably in words of one, maybe two at most, syllables) how this comes about, and what it means?

1. Simple explanation.
If you know that a system has energy but no momentum, using simple relativistic considerations, you should easily conclude that it has rest mass, isnt'it?
Ok. Now, consider the system of two photons of exactly the same energy, travelling in opposite directions. This system has clearly non-zero energy but zero momentum (total p = p1 - p1 = 0). So, the system mast have a rest mass!

2. Just a bit less simple explanation.
The exact formula relating rest mass m, energy E and momentum p of a relativistic system of any kind, is:
(E/c)2 - |p|2 = (mc)2
So, if p = 0, then (E/c) = mc --> m = E/c2 ≠ 0 because E ≠ 0 (in this case, E = 2hν).

Quote
Do you mean that two photons that are somehow bound, and it is the binding energy that has mass; or do you mean that even two independent photons are measured to have mass?

Very good question! Don't know. I would say even two indipendent photons, but I'm not sure.
The fact is that if you observe the system of two photons I've described up, from a moving ref. frame, the two photons don't move in the described way, anylonger: you will see the two photons travelling away from each other forming an angle < 180°; but the rest mass of the system is invariant, so it's exactly the same in this new frame, so, I assume you can pick up any pair of travelling photons in the universe, with the prescription they are not travelling exactly in the same direction and sense (that is, their trajectories form a non-zero angle), and you'll have a non-zero rest mass system.

What all this could exactly mean, is a mystery to me.
Title: what is Mass?
Post by: another_someone on 25/05/2007 16:29:34
1. Simple explanation.
If you know that a system has energy but no momentum, using simple relativistic considerations, you should easily conclude that it has rest mass, isnt'it?
Ok. Now, consider the system of two photons of exactly the same energy, travelling in opposite directions. This system has clearly non-zero energy but zero momentum (total p = p1 - p1 = 0). So, the system mast have a rest mass!

2. Just a bit less simple explanation.
The exact formula relating rest mass m, energy E and momentum p of a relativistic system of any kind, is:
(E/c)2 - |p|2 = (mc)2
So, if p = 0, then (E/c) = mc --> m = E/c2 ≠ 0 because E ≠ 0 (in this case, E = 2hν).


It sounds to me simply to be a consequence of the notion that light can have energy, and momentum, and thus mass, while in motion, while having zero rest mass in the first place.  More specifically, it is down to the inevitable paradoxes one gets when one deals with infinities (the existence of light implies an assumption of zero rest mass multiplied by an infinite Lorenz factor because it is travelling at the speed of light - so don't be too surprised if you get quirky results).
Title: what is Mass?
Post by: lightarrow on 25/05/2007 19:22:19
It sounds to me simply to be a consequence of the notion that light can have energy, and momentum, and thus mass,

Here you are talking about relativistic mass, which is a concept physicists advice not to use anylonger. I was talking about rest mass of photons, which is 0 for one photon and non 0 for 2 of them!
Title: what is Mass?
Post by: another_someone on 25/05/2007 20:14:01
It sounds to me simply to be a consequence of the notion that light can have energy, and momentum, and thus mass,

Here you are talking about relativistic mass, which is a concept physicists advice not to use anylonger. I was talking about rest mass of photons, which is 0 for one photon and non 0 for 2 of them!

Yes, but as I understand what you are doing is that you are taking the relativistic notions of energy and momentum, which implicitly include relativistic mass, and then back propagating to an implied rest mass.

Energy and momentum are thus:
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fupload.wikimedia.org%2Fmath%2F0%2Fe%2F4%2F0e419401477937951f338ef318c3d020.png&hash=7ceafdcd56c1bf0a62e9f99b1915b45b)
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fupload.wikimedia.org%2Fmath%2F0%2Fd%2Fe%2F0de7c35654c4a75d1799c03b4a5c9376.png&hash=56f1b0aac20bf36112eded74e8e006ad)
where γ is the Lorentz factor.

Since both of those factors include both rest mass (zero) and the Lorenz factor (infinite when one is at the speed of light), so one inevitable has zero multiplied by infinity.

Clearly, with light, the situation is the converse to normal, in that we can measure energy and momentum, but cannot measure rest mass; so the equations are inverted, but you still have the fundamental mix of a measureable quantity divided by infinity returning an assumed zero.
Title: what is Mass?
Post by: lightarrow on 26/05/2007 15:00:40
Yes, but as I understand what you are doing is that you are taking the relativistic notions of energy and momentum, which implicitly include relativistic mass, and then back propagating to an implied rest mass.

Energy and momentum are thus:
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fupload.wikimedia.org%2Fmath%2F0%2Fe%2F4%2F0e419401477937951f338ef318c3d020.png&hash=7ceafdcd56c1bf0a62e9f99b1915b45b)
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fupload.wikimedia.org%2Fmath%2F0%2Fd%2Fe%2F0de7c35654c4a75d1799c03b4a5c9376.png&hash=56f1b0aac20bf36112eded74e8e006ad)
where γ is the Lorentz factor.

With these formulas you would certainly have strange results, since they are simply wrong for photons (and for 0 mass objects in general). Those are only valid for non 0 mass  objects and travelling at v ≠ c.

The one valid for every object is (E/c)2 - |p|2 = (mc)2  as I've already written in the other post.
Title: what is Mass?
Post by: another_someone on 26/05/2007 15:37:23
With these formulas you would certainly have strange results, since they are simply wrong for photons (and for 0 mass objects in general). Those are only valid for non 0 mass  objects and travelling at v ≠ c.

The one valid for every object is (E/c)2 - |p|2 = (mc)2  as I've already written in the other post.

Is there not a paradox here.

You are saying that you are using an equation that is only valid for massless particles to calculate that the particle is not massless (or, at least that the collections of particles are not massless).  If the particles are not massless, then how can you use an equation that is only valid for massless particles?
Title: what is Mass?
Post by: lightarrow on 26/05/2007 20:21:46
With these formulas you would certainly have strange results, since they are simply wrong for photons (and for 0 mass objects in general). Those are only valid for non 0 mass  objects and travelling at v ≠ c.

The one valid for every object is (E/c)2 - |p|2 = (mc)2  as I've already written in the other post.

Is there not a paradox here.

You are saying that you are using an equation that is only valid for massless particles to calculate that the particle is not massless (or, at least that the collections of particles are not massless).  If the particles are not massless, then how can you use an equation that is only valid for massless particles?

Probably I didn't express myself clearly.
The equation I use: (E/c)2 - |p|2 = (mc)2
is valid for all kinds of particles, massless and not massless, it's the most general one.

The equations you wrote:
E = γmc2
p = γmv
are valid only for not massless particles.
Title: what is Mass?
Post by: another_someone on 27/05/2007 23:31:20
Probably I didn't express myself clearly.
The equation I use: (E/c)2 - |p|2 = (mc)2
is valid for all kinds of particles, massless and not massless, it's the most general one.

Sorry, I did misunderstand that.

On the other hand, if the equation is true for both massless and non-massless bodies; and for all such bodies, it can represent a mass for two objects that is different from the sum of the masses of the single objects, then should that not be just as true for tennis balls as for photons?
Title: what is Mass?
Post by: lightarrow on 28/05/2007 23:38:29
Probably I didn't express myself clearly.
The equation I use: (E/c)2 - |p|2 = (mc)2
is valid for all kinds of particles, massless and not massless, it's the most general one.
Sorry, I did misunderstand that.
On the other hand, if the equation is true for both massless and non-massless bodies; and for all such bodies, it can represent a mass for two objects that is different from the sum of the masses of the single objects, then should that not be just as true for tennis balls as for photons?
Yes, if the tennis balls are moving, but the effect is negligible at non-relativistic speeds, that is, m1 + m2 ≈ mass of the system of the 2 balls.
The effect is so striking with photons because they travel at c.

Let's make some computation.

we have 2 tennis balls, each having:

m = 100g = 0.1Kg; so m1 + m2 = 2m = 0.2Kg.
v = 30m/s

p = m*v = 0.1*30 = 3 Kg*m/s (actually, we should write p =m*v*γ, but it's easy to see that the result wouldn't change, at the level of accuracy we will find);

E = Sqrt[(cp)2 + (mc2)2]

and they travel in opposite directions.

be:  
ms Es, ps the mass, energy and momentum of the system of 2 balls. We have:
Es = 2E because energy is additive;
ps = 0 because the 2 balls are travelling in opposite directions;
(msc2)2 = (Es)2 - (cps)2 = (Es)2
so:
ms = Es/c2 = 2E/c2 = 2 Sqrt[(cp)2 + (mc2)2]/c2 =

2 Sqrt[(p/c)2 + m2] = 2 Sqrt[(3/3*108)2 + (0.1)2] = 2 Sqrt(10-16 + 10-2) =

= 2*10-1 Sqrt( 1 + 10-14) ≈ 2*10-1 = 0.2Kg.
Title: what is Mass?
Post by: another_someone on 29/05/2007 01:56:02
OK, I see what you are saying.

That for any particle or object, if two of them are moving antiparallel directions, they will have a greater calculated rest mass than if they travel in parallel; but that for low speed objects, most of the energy in the particle is bound up in the rest mass anyway, so the amount of kinetic energy is too insignificant to cause the confusion in rest mass.

So ant particle, be it massless or non-massless; if it has kinetic energy that is comparable to the zero velocity rest mass, then the calculated rest mass using that formula for particles that are antiparallel will differ from the rest mass of the same particles travelling in parallel.

As such, it does bring into question whether the equation can really be used to measure true rest mass, since true rest mass I would expect to be the mass of the object with zero kinetic energy, and if that equation causes a different answer to that, then the equation sounds wrong.
Title: what is Mass?
Post by: lightarrow on 29/05/2007 11:51:48
OK, I see what you are saying.
That for any particle or object, if two of them are moving antiparallel directions, they will have a greater calculated rest mass than if they travel in parallel; but that for low speed objects, most of the energy in the particle is bound up in the rest mass anyway, so the amount of kinetic energy is too insignificant to cause the confusion in rest mass.
So ant particle, be it massless or non-massless; if it has kinetic energy that is comparable to the zero velocity rest mass, then the calculated rest mass using that formula for particles that are antiparallel will differ from the rest mass of the same particles travelling in parallel.
Exactly.
Quote
As such, it does bring into question whether the equation can really be used to measure true rest mass, since true rest mass I would expect to be the mass of the object with zero kinetic energy, and if that equation causes a different answer to that, then the equation sounds wrong.
Infact, calling that m "rest mass" is not appropriate, in this case; some physicist call it, better, "invariant mass" and I agree with them. You could say that, in the case of two objects travelling in opposite directions with total p = 0, however, the system is "at rest" because it is its centre of gravity; however it would be very tricky to keep calling m "rest mass".
The term everyone should use is invariant mass simply because it doesn't change from a ref frame to another, and this is what really counts.
Title: what is Mass?
Post by: another_someone on 29/05/2007 16:02:51
Infact, calling that m "rest mass" is not appropriate, in this case; some physicist call it, better, "invariant mass" and I agree with them. You could say that, in the case of two objects travelling in opposite directions with total p = 0, however, the system is "at rest" because it is its centre of gravity; however it would be very tricky to keep calling m "rest mass".
The term everyone should use is invariant mass simply because it doesn't change from a ref frame to another, and this is what really counts.

In what way is it an invariant mass?

In fact, no mass is actually invariant; but the notion of 'rest mass' derives from the mass that an object would have in the absence of any kinetic energy, whereas the equation (E/c)2 - |p|2 = (mc)2 must include kinetic energy (otherwise there would not be any momentum, even for a lone particle, and thus the paradox we are talking about disappears).

In practical terms, what measurable quantity does this equation provide?  It does not show an apparent mass (because that would be the full relativistic mass), and it does not show the mass measured when the system is at rest - so what measurable quantity would relate to this number?
Title: what is Mass?
Post by: lightarrow on 30/05/2007 14:17:08
Infact, calling that m "rest mass" is not appropriate, in this case; some physicist call it, better, "invariant mass" and I agree with them. You could say that, in the case of two objects travelling in opposite directions with total p = 0, however, the system is "at rest" because it is its centre of gravity; however it would be very tricky to keep calling m "rest mass".
The term everyone should use is invariant mass simply because it doesn't change from a ref frame to another, and this is what really counts.
In what way is it an invariant mass?
I wrote it:
"The term everyone should use is invariant mass simply because it doesn't change from a ref frame to another, and this is what really counts"
Quote
In fact, no mass is actually invariant;
What do you mean? The m defined above is invariant.
Quote
but the notion of 'rest mass' derives from the mass that an object would have in the absence of any kinetic energy,
But what do you mean with "kinetic energy"? For a single particle, kinetic energy is the energy due to the particle's movement, but for a system of two particles travelling in opposite directions with total p = 0, it is not: the system has no kinetic energy, just because total p = 0. Kinetic energy is cp.
Quote
whereas the equation (E/c)2 - |p|2 = (mc)2 must include kinetic energy (otherwise there would not be any momentum, even for a lone particle, and thus the paradox we are talking about disappears).
In practical terms, what measurable quantity does this equation provide?  It does not show an apparent mass (because that would be the full relativistic mass), and it does not show the mass measured when the system is at rest - so what measurable quantity would relate to this number?
But m is the mass of the system in the ref. frame in which the system's kinetic energy is 0; it's only that it's difficult (for me, at least!) to call it "rest mass" for a system of two balls or particles that travels at high speed in opposite directions, you know what I mean?
Title: what is Mass?
Post by: another_someone on 31/05/2007 00:52:28
I wrote it:
"The term everyone should use is invariant mass simply because it doesn't change from a ref frame to another, and this is what really counts"

Not sure even this is true.

The equation (E/c)2 - |p|2 = (mc)2 will assume that |p|2 is zero in only one particular frame of reference.  If p = γmv for each of the two particles (which it will be is we are talking about non-massless particles at less than the speed of light), then it follows that p changes according to the frame of reference you use.

If you are in a frame of reference where you have two particles, each approaching you at equal velocity from opposite directions, then clearly the sum of the momentum of the two particles is zero.  But equally, you can choose a frame of reference where one particle is stationary in respect to you (and thus has zero momentum), while the other particle has a momentum:

p' = 2mv1/sqrt(1 – 4v12/c2)

Would not your calculated “invariant mass” be different in this reference frame?

What you do seem to be saying is that it is the “rest mass” of the system (i.e. the mass of the system when the sum of the velocity of the component parts of the system are zero, thus making the system as as a whole appear to be at rest relative to the observer), where the component parts of the system are not necessarily at rest (i.e. where all the component parts of the system may be in motion, but the total system itself is not in motion).

This would seem more sensibly to be regarded as a systemic rest mass, rather than any sort of reference invariant mass.  Thus, you are saying that a system of two photons can have a non-zero systemic rest mass, but that in any system, the rest mass of the system may be different from the sum of the rest masses of its component parts, if the component parts of the system are not at rest.

This is probably not unreasonable, since you are not actually measuring the rest masses of the component parts of the system, but the apparent masses as they occur within the system (i.e. the relativistic masses of the individual component parts).
Title: what is Mass?
Post by: another_someone on 31/05/2007 01:03:08
Ofcourse, if one follows the logic of the above, could all mass that we see merely be composed of “systemic rest masses” - i.e. could non-massless particles, such as electrons, really simply be systems composed of massless particles, and what we perceive as the rest mass of an electron, merely be the rest mass of the system of massless particles of which the electron is composed, and the component sub-particles within that system remain in motion, even as the system appears to be at rest?
Title: what is Mass?
Post by: lightarrow on 31/05/2007 13:39:46
I wrote it:
"The term everyone should use is invariant mass simply because it doesn't change from a ref frame to another, and this is what really counts"
Not sure even this is true.
The equation (E/c)2 - |p|2 = (mc)2 will assume that |p|2 is zero in only one particular frame of reference.  If p = γmv for each of the two particles (which it will be is we are talking about non-massless particles at less than the speed of light), then it follows that p changes according to the frame of reference you use .

Absolutely! But E also changes, and in such a way that (E/c)2 - |p|2 is invariant.
Quote
This would seem more sensibly to be regarded as a systemic rest mass, rather than any sort of reference invariant mass.  Thus, you are saying that a system of two photons can have a non-zero systemic rest mass, but that in any system, the rest mass of the system may be different from the sum of the rest masses of its component parts, if the component parts of the system are not at rest.
Yes.
Quote
This is probably not unreasonable, since you are not actually measuring the rest masses of the component parts of the system, but the apparent masses as they occur within the system (i.e. the relativistic masses of the individual component parts).
No, I talk about rest masses of the components, and rest mass of the system. (This is the only universally recognized useful concept of "mass").
Title: what is Mass?
Post by: Mr. Data on 02/07/2011 15:47:19
What is mass?

Mass is a charge, fundamentally speaking, as a Higgs field interacts with a massless particle. Through a process of spontaneous symmetry-breaking, the photon (as an example of a massless particle) would obtain a mass by gobbling up a Goldstone Boson.

But what really is mass?

Mass is a concentrated form of energy. You can measure how compact the energy is if you apply the equation E=Mc2. This is non-relativistic, however, but the rest mass assures us that by using c2 as a scale factor, we can certainly get a lot of energy from a tiny bit of mass: because of this, energy must be a diffused state of matter.

So simply, mass the compact structure of a more concentrated energy - and this energy occupies the intrinsic structure of the particle, providing it with other interesting things, like charge, (or if absent of electric charge) some kind of magnetic dipole.
Title: what is Mass?
Post by: lightarrow on 05/07/2011 20:46:07
Wrong. According to your idea, a photon with total energy E and an electron with total energy E should have the same mass, but it's not.
Title: what is Mass?
Post by: Mr. Data on 05/07/2011 23:41:30
Wrong. According to your idea, a photon with total energy E and an electron with total energy E should have the same mass, but it's not.

No, you apply E=Mc2 to an individual particle system. Sure you can work out different values for mass, but for a photon, it does not even have a mass. But that's a whole different ball game involving more difficult field processes I doubt you could fully understand unless you sat down and learned this stuff.

But you would not have said what you did, if you had read my post and understood also what was said. I said E=Mc2 is non-relativistic, meaning it does not apply to particles travelling at or near light speed.
Title: what is Mass?
Post by: JP on 05/07/2011 23:47:03
But you would not have said what you did, if you had read my post and understood also what was said. I said E=Mc2 is non-relativistic, meaning it does not apply to particles travelling at or near light speed.

That's an understatement, since it only applies in the rest frames of particles, which is as far from light speed as they can get.  That equation is wrong if the particle is moving in your reference frame--and of course light is always moving.
Title: what is Mass?
Post by: Mr. Data on 05/07/2011 23:51:45
But you would not have said what you did, if you had read my post and understood also what was said. I said E=Mc2 is non-relativistic, meaning it does not apply to particles travelling at or near light speed.

 
That's an understatement, since it only applies in the rest frames of particles, which is as far from light speed as they can get.  That equation is wrong if the particle is moving in your reference frame--and of course light is always moving.

This is an overstatement.

We are not talking about light. Light does not even have a mass - E=Mc2 is a relatively good estimate for particles travelling at non-relativistic speeds. In fact, the nature of speed, should not even be an issue here. The question is about mass, what mass is, and E=Mc2 was used to describe it. Now if we had been talking about photons (which I had not been, nor the OP) then the equation to worry about would have been E2=p2c2 + M2c4. But it wasn't needed.
Title: what is Mass?
Post by: JP on 06/07/2011 00:24:42
Uh huh.  It's a good estimate. 

However, E2=p2c2 + M2c4 tells you a more complete story and includes the cases where the particle is moving or the particle happens to be a photon.
Title: what is Mass?
Post by: Mr. Data on 06/07/2011 00:41:58
Why would we want to talk about photons? They contain none of the relevent information to answer the question of what mass is...
Title: what is Mass?
Post by: Mr. Data on 06/07/2011 03:14:00
If you want a technical, mathematical explanation, then I will most happily write out some math tomorrow, or the next day and explain how photons and their fields predict the presence of a Higgs field in the presence of some symmetry-breaking. But you will need to know just some basics of partial differentiation for quantum fields, and whilst that part sounds difficult, it's really not.
Title: what is Mass?
Post by: Mr. Data on 06/07/2011 03:15:46
Whilst a Higgs field explains the presence of a mass, which is synonymous to a symmetry-breaking in something like a photon field, the photon alone does not answer what mass is - it, and it's field can answer for the presence of the Higgs Boson if you satisfy breaking the symmetries. Of course, however, the Higgs field does not exactly explain why inertia is experienced; all we can surmise from relativity is that inertial mass and gravitational mass are equal. The Weak equivalence.
Title: what is Mass?
Post by: lightarrow on 06/07/2011 10:09:40
Wrong. According to your idea, a photon with total energy E and an electron with total energy E should have the same mass, but it's not.

No, you apply E=Mc2 to an individual particle system. Sure you can work out different values for mass, but for a photon, it does not even have a mass. But that's a whole different ball game involving more difficult field processes I doubt you could fully understand unless you sat down and learned this stuff.

But you would not have said what you did, if you had read my post and understood also what was said. I said E=Mc2 is non-relativistic, meaning it does not apply to particles travelling at or near light speed.
About the concept of mass, I have understood to be quite careful and to make very precise statements, despite its seeming simplicity. You wrote:

"Mass is a concentrated form of energy"

and I reply:
mass is not "a form of energy", mass "is" energy. But that statement is not complete, because we have to add: "fixed a system in space". If it moves, then it's not true anylonger.
examples:
1) I heat a piece of iron which is "not moving in the frame of reference I have chosen", giving it an amount of thermal energy equal to ΔE; its mass increases of an amount Δm. It comes out that Δm = ΔE/c2.
2) That piece of iron has the shape of a spring. I give it the energy ΔE as elastic potential energy by compressing it of the appropriate amount. Its mass increases of Δm.
3) I give it ΔE as any other form of energy. Its mass increases of Δm.
4) I choose to consider a void volume of space. Its mass is zero. Then a beam of light goes through it, for a brief instant. During that instant, the mass of the system increases of Δm = ΔE/c2, if ΔE is the average light beam's energy in that volume of space during that brief instant of time.

It doesn't matter what form of energy ΔE I give to the piece of iron,
It doesn't matter what form of energy ΔE I give to the fixed system I am considering, its mass increases of Δm.
 
Conclusion: mass is not "a form of energy", mass "is" energy, provided the piece of iron or the system I'm considering doesn't move in space.

So, you don't have to explain what mass is, you already have an explanation.

Just to precise your statement.
Title: what is Mass?
Post by: Mr. Data on 06/07/2011 10:21:45
Huh?

The word ''form'' does not imply a direct difference. The statement mass is a concentrated form of energy does not imply a difference either. ''Form'' is simply another word for ''structure''. Replace that with ''form'' in my sentence:

Mass is just a concentrated structure of energy.

The use of the word is not implying a difference between mass or energy. It is just as right as saying directly mass is energy and energy is mass. But saying it like the latter has less meaning than my statement, and I will leave it to you to figure out why.
Title: what is Mass?
Post by: Mr. Data on 06/07/2011 16:40:50
Let us take a simple scalar field, with a non-invariant gauge condition - this means there is no symmetry present in the field equations:

∂φ'=[∂φ + iφ(∂θ/∂x)]e

∂φ'*=[∂φ* + iφ*(∂θ/∂x)]e

Multiplying these two terms (which make up the kinetic term of a field), we have:

[∂φ + iφ(∂θ/∂x)]e•[∂φ* + iφ*(∂θ/∂x)]e=∂φ∂φ* + i(φ∂φ* - φ*∂φ)∂θ/∂x + φ*φ(∂θ/∂x)²

Which has no symmetry at all. So mathematicians needed to make a new mathematical concept, called the Covariant Derivative, and this brought order back into our equations, and it uses the four-vector of electromagnetism:

Dμφ = ∂μφ + A\muφ

Dμφ* = ∂μφ* - A\muφ*

This is just a wee taster... but plugging that term into our field restores invariance and so this is a similar reason why a photon cannot have a mass. Only if there was some breaking of the symmetry could we state such things.



Title: what is Mass?
Post by: Mr. Data on 06/07/2011 16:43:13
Note though that I haven't included a potential term here. You could if you wanted to.
Title: what is Mass?
Post by: Mr. Data on 06/07/2011 18:16:20
Now let us debate on the existence of the Higgs field. It is true that mathematics is an abstraction, and it does not represent the true physical reality. It is merely a tool we use to help us describe the world, but it does not refer to the real world; It can only be like this, since mathematics opens the realm of different interpretations, and thus only through measurement can we adjust the equations to a greater degree of certainty. Whether we will know the entire blueprint of reality at some point in our future horizon is another question up for debate, that is saying if we can even simplify something as complicated as a universe.

There is no clear definition of a Higgs field when it comes to important questions like inertia, a property inherent in systems in which the behaviour of the system is changed intrinsically and in a non-symmetric sense to the more fundamental field (the photon field) and dynamically, meaning that the dynamics of the particle, whether theyn involve observable properties have been changed. Not only is energy a measurable quantity, but mass is also an observable and predicted upon the density of the amplitude of the function.

It is also a strange idea we call the Goldstone Boson, its name, as it is really simply just a photon in the lowest energy state - this often confuses people as it may imply something odd and exotic. But it really isn't, it's just a matter of the least principles of energy on a system - a langrangian, which may take the lowest energy state possible. This state never reaches an absolute zero temperature, which would be denoted simply as T=0, or a zero vacuum state vector Ψ|0> because no such system can exist in the vacuum of space, simply because space is infinitely filled with energetic fluctuations.

So the Goldstone Boson should be (a weakly fluctuated) kinetic packet of energy, around some lower bound potential φ = 0 where φ is your field and 0 refers to the lowest state.
Title: what is Mass?
Post by: Mr. Data on 06/07/2011 19:19:08
But some kind of differential must come into play if we talk about:

'' lower bound potential φ = 0 where φ is your field and 0 refers to the lowest state.''

Since  Ψ|0> ≠ ρ(e•e-iθ) we can assume that there is some inherent change in φ which represents the potential scalar. Whether we look for some symmetry breaking, it will be at the cost of either excepting a Higgs phenomenon or believing there is some more unique symmetry in θ which may invoke connections on other terms. This could obviously drastically change our look on the dynamics of

[∂φ + iφ(∂θ/∂x)]eiθ•[∂φ* + iφ*(∂θ/∂x)]eiθ=∂φ∂φ* + i(φ∂φ* - φ*∂φ)∂θ/∂x + φ*φ(∂θ/∂x)²

Perhaps there are restraints on certain variables which invoke the vanishing of the term which causes the non-invariance. This could only be done by a super-connection in a higher representation of a probability field - the field represented by Ψ should have a conjuugate Ψ* and if coupled to components to the i'th components could alter dimensions in the field sufficiently to fine tune dynamical reasons for matter, rather than appealing to a new field, that being the Higgs Field, of course.

It would look something like:

([∂φi + iφi(∂θ/∂x)]eiθ•[∂φi* + iφ*i(∂θ/∂x)]eiθ)Ψi = (∂φi∂φ*i + i(φi∂φ*i - φ*i∂φi)∂θ/∂x + φ*iφi(∂θ/∂x)²)Ψi

The connections are a probability matter: The new function Ψ should measure the probabilities in all measurements in the intrinsic properties of the system. The sub-component relating Ψi with φi which is obviously i can be further translated into tensor products, but we shall leave that kind of thing out in this part. All we should need to know is that the potential of the system (the Goldstone Boson) depends on rotations in it's abstract spacetime to alter the existing non-gauge invariant terms to existing parameters which are allowed. What causes this as of yet could be claimed, as somewhat of a mystery, since this approach has never been fully investigated out the conventional claims of a Higgs Boson. Of course, once we have established this function over all our terms, we can then change the terms to suit some new differential equation. That could be speculated upon how it could form, but such an approach should be possible. It maybe some kind of equation where it takes the space derivative to the second order, whilst the right hand side of an equation represents the time derivative taken to the field to the first order. Such an equation can be allowed, but can only permit the space component, with a vanishing time component (if I have conducted this properly). But either way, that is but an approach.
Title: what is Mass?
Post by: Mr. Data on 06/07/2011 19:30:43
But that is but one way, and there may be many possible ways to approach it, but if you take my way, you find some interesting results.
Title: what is Mass?
Post by: lightarrow on 06/07/2011 20:39:19
Mass is just a concentrated structure of energy.
But where in this statement one can understand that you are considering a region of space which is not moving?
Title: what is Mass?
Post by: yor_on on 06/07/2011 20:56:38
I don't follow Mr Data?  Are you building a field theory depending on some lowest state of energy, that then also would couple to mass?

How do it couple?
=

Vacuum fluctuations that gets dense over 'time's arrow?
And what about Accelerations, as compared to Geodesics.
=

One might assume that as we describe photons as the 'force carriers' of electro magnetism, and as they bend to gravity, they also should be able to bend to a electric field, but I haven't seen that proved in any experiment yet?

Because if they did :) And assuming we all are EM in some way, then ?
But I don't think so myself.
Title: what is Mass?
Post by: Mr. Data on 06/07/2011 21:10:38
I don't follow Mr Data?  Are you building a field theory depending on some lowest state of energy, that then also would couple to mass?

How do it couple?
=

Vacuum fluctuations that gets dense over 'time's arrow?
And what about Accelerations, as compared to Geodesics.

Coupling the terms is very easy. All you need is to obide by the terms where the function of field comes into play. If you look at the coupled terms in the last equation above, it takes the appearance of:

For all u it represents

(u+u) d+d = ud + (ud - du) + du

where u is the up-down model, where this is ''up'' φ and d is ''down'' φ* - or if you like, you can call both terms as an incoming and outgoing signal. Every time you see these terms, they are the wave operators on the field. All you need to do, is take the wave functions condition and shift the field φ to φ' - θ is the phase and located in the exponential, and it can take many trig metric functions. These shifts can be suited to satisfy an appearance of a spontaneous symmetry breaking if and only if there are terms in the gauge symmetric field which cannot be satisfied.
Title: what is Mass?
Post by: Mr. Data on 06/07/2011 21:21:34
You might notice an antisymmetric part in the representation above (ud - du).

This is a very interesting quantity which can be evolved in a matrix, and seen in light of the hodge star, but that will be later explained when I have more time.
Title: what is Mass?
Post by: yor_on on 06/07/2011 21:24:21
I will have to reread this :)
Several times for sure.

It's interesting.

"the potential of the system (the Goldstone Boson) depends on rotations in it's abstract spacetime to alter the existing non-gauge invariant terms to existing parameters which are allowed." here we are speaking totally abstractly right?
all in the 'mind sphere', so to speak, although those rotations reminds me of the 'folds' described in the Fractional Quantum Hall (FQH) Effect, which also was related to how that electron needed to 'turn' 720 degrees to get a full rotation.

So, and this is what nags on me, could I relate it to dimensions, or should I strictly think of it as a 'translation' from the mathematics?
==

You have to remember one thing here. It's exactly as JP pointed out, the more exotic your equations the less people will be able to follow them. And some of them might build on definitions you take for granted, but that I miss. Don't let that stop you though :)
Title: what is Mass?
Post by: yor_on on 06/07/2011 21:47:03
Let us see if I can define a Higgs field in words. It's as you say about a lowest state of energy, the one our vacuum seems to have, a average null. That doesn't state that it is null though everywhere though. The vacuum fluctuates like a sea does but without any wind to help it. And gravity would then be represented by some of the bosons existing inside those fluctuations, they may fluctuate but as they do so over a region their average existence becomes coupled to what we call inertial mass, getting a average value differing from 'null', so it's a very tricky idea in that we can't measure one of those bosons, as all measurements will fail to register such a probabilistic (short timed) 'boson', but the average field created from them will be 'invariant'.

So on one hand you have a classically empty space. On another it's constantly 'fluctuating'. On a third those 'bosons' treated as a average, will have a influence on what we can measure, in this case expressing itself as 'gravity'.
=

the weirdest thing with this idea is that it assumes a value of the Higgs field that somehow seems to be separated from what we observe as 'space'. It's average 'energy' isn't in the same plane, sort of. And that one weirds me out, in many ways. It seems actually to assume a new definition of a 'dimension', not that I'm sure on the old one either :)
Title: what is Mass?
Post by: Mr. Data on 06/07/2011 21:53:15
You ask a very relative question. What is this rotation in the field? It is a geometrical representation, which would not apply to point like particles. As we have seen from recent news, the electron may indeed have a sphere-like structure, which agrees well with classical idea's. It is up to the reader to decide whether or not the electron has a structure and whether or not the model refers to real rotations in some kind of real geometry or whether it is all just a mathematical representation. Just that, I cannot say.
Title: what is Mass?
Post by: Mr. Data on 06/07/2011 21:55:45
The technical explanation would possibly be described as a special oscillating value between C and R (complex and real) values, which would be part of the U(1) symmetry group. It would then be a special case directly of the U(1) symmetry group.
Title: what is Mass?
Post by: yor_on on 06/07/2011 22:00:22
To me it's all about what a dimension is nowadays Mr Data :) I finally feel that I have gotten some ground rules down for how to see 'frames of reference' relativistically. And 'dimensions' is my new project, I want to see them..

ahem :)
Title: what is Mass?
Post by: yor_on on 06/07/2011 22:08:37
Any 'geometrical representation' seems, to me that is, to build on the idea of 'dimensions'? The way you define it mathematically should either translate to what we see, or stay as a 'ideal idea' of something that doesn't exist. How it then can be accepted to have a real influence I don't know. I could describe the sun as the eye of the mythical Kee, whose rays pierce me with her mystical powers, but I prefer a more prosaic definition. And so those mathematical spaces, if we expect them to influence our day to day experiences, must 'exist' in some more way than just as a mathematical space set. If I now make sense here.
==

You could of course assume us to be some data bits, in some electronic space, or holographic. But that doesn't explain what we are and experience. I prefer a prosaic definition first, a conceptual only when I find my 'prosaic definitions' to end, and I haven't reached that state yet.
Title: what is Mass?
Post by: Mr. Data on 06/07/2011 22:21:46
u \wedge d = A(u \otimes d)

where A is the anti-symmetric operator. This means

(ui dj - dj ui)

(u Λ v)(a,b) = A(u \otimes d)(a,b)

=1/2(u(a)d(b) - u(b)d(a))

(*1)ijk = εijk

Where * is the hodge star, this relationship can be understood if you know that it is the hodge star of the identity element in 3 dimensions.

Four dimensional analysis can be neglected if you take the idea that the vacuum is spacelike in nature and only timelike in psychological experience. In fact, many papers that have been written on a similar paradox, the time problem of QM seem to indicate that time does not exist.

This is where you can violate Lorentz invariance.
Title: what is Mass?
Post by: Mr. Data on 06/07/2011 22:29:48
Any 'geometrical representation' seems, to me that is, to build on the idea of 'dimensions'? The way you define it mathematically should either translate to what we see, or stay as a 'ideal idea' of something that doesn't exist. How it then can be accepted to have a real influence I don't know. I could describe the sun as the eye of the mythical Kee, whose rays pierce me with her mystical powers, but I prefer a more prosaic definition. And so those mathematical spaces, if we expect them to influence our day to day experiences, must 'exist' in some more way more than just as a mathematical space set. If I now make sense here.
==

You could of course assume us to be some data bits, in some electronic space, or holographic. But that doesn't explain what we are and experience. I prefer a prosaic definition first, a conceptual only when I find my 'prosaic definitions' to end, and I haven't reached that state yet.

Yes it should relate to something physical, and if you work out the equations for a Hamiltonian that satisfies E=δMc^2 where the two possibilities lead two positive solutions and negative solutions. It may, as I have suspected, refer to an energy density of two states of measure as found in the Dirac Equation, which means the equations could be readily used to satisfy that equation by merging the idea that there is some abstract space which is a dynamical change in the structure of a particle.
Title: what is Mass?
Post by: yor_on on 06/07/2011 22:39:06
Ah okay, then we agree on that one :)
And welcome to the forum, if now nobody have said it.

The Hodge star is a geometric function related to the metric you define, if I understands it right? You define reality as 'time-like psychologically' here? Assume you are in a coma, also define it such as I do from 'locality', meaning that I'm the sole representation of this unique 'frame of reference' that psychologically follows me around, by me defined as the one invariant 'thing' that never changes consisting of a 'intrinsic' time experience and 'c'. Why would the translations of others fit the experienced 'time' I find when I wake up? If time can be defined as a 'psychological state'?

Of course it depend on how you define that state as 'psychological', but that's also where I find it hard to see.
Title: what is Mass?
Post by: Mr. Data on 06/07/2011 22:48:50
In short, it seems that it can be acceptable to assume that potential energy can create mass. To explain mass, you need to explain it as a charge from the potential field φ. To do this you need to evaluate the field density to a refined part of space. Calculating this would have a value of:

ρ ≈ g(Mφ)

where the local parameters exist on both sides, so ρ equals a local density energy parameter. Because we have allowed ourselves to take some arbitrary value of φ, this potential energy could be contributed to real mass! There is even a process which should fundamentally explain if the potential actually contributes to anything real, through the confinement potential. This is a quark potential smush of information. It all conrtibutes to inertial mass when reaching a certain energy on ∫|ψ|², which would be some interaction. The interaction of φ and M would imply it's own charge conservation: this means an interaction term may be constructed from: ψ*ψM . Whatever or however we construct this field is irrelevent at this time. All that needs to be known is that the mass of a particle is a charge in itself, and that the mass of most particles involve the potential gradients of quark interactions. So in principle, expecting energy from a potential φ has been given a stamp of approval.
Title: what is Mass?
Post by: yor_on on 06/07/2011 22:58:20
If I'm reading you right you define it the same way I treat 'frames of reference', as strictly locally? It's a 'psychological identifier' defining each one of us intrinsically, from where we observe 'reality', (as in all other 'frames of reference'). Is that a correct statement? If so :)

That's interesting, didn't know that one.

I need to read up on Hodge stars Mr Data :)
It's a new one to me.
Title: what is Mass?
Post by: Mr. Data on 06/07/2011 23:05:34
If I'm reading you right you define it the same way I treat 'frames of reference', as strictly locally? It's a 'psychological identifier' defining each one of us intrinsically, from where we observe 'reality', (as in all other 'frames of reference'). Is that a correct statement? If so :)

That's interesting, didn't know that one.

I need to read up on Hodge stars Mr Data :)
It's a new one to me.

Think more on the EM-field ''way of things''. A particle only experiences a charge due to EM effects as it moves through an EM-field. Think now of applying this idea to mass, as a charge itself on the system. A particle moving in a gravitational field will experience a mass. You know, in a classical criteria, Nordstrom predicted the same thing by saying the density of mass depended on the gravitational field

box φ = ρ

Taking this literally, there should be intrinsic conditions in why certain parts of an equation disappear. Thus it is understood in terms of learning the limits of this process.
Title: what is Mass?
Post by: Mr. Data on 06/07/2011 23:10:46
If you want charge in this, you must make sure if you ever write it in terms of density, it is a squared quantity:

ψ*ψe2M

I'm wondering if M needs to be extended a power, but I am not sure right now. I'm stuck between several things right now.



Title: what is Mass?
Post by: yor_on on 06/07/2011 23:17:45
Yes, I can see the analogue, but in a geodesic there is no weight? So we need to define it to inertia, as I understands it, not 'gravity' as the overall term. As when you resting in your bed being 'still', still will feel that 'gravity' acting on you. That is if you accept that we relativistically can define Earth as being at rest for this? Or is there a definition that defines it otherwise?
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If you define a uniform motion as taking you from 'A' to 'B' in some positional system (in deep space), then you will find 'inertia' existing, but you won't find gravity? Maybe that's the best example of how I think. There is naturally the question of invariant mass moving with you, but you will still find yourself weightless. Still, if you imagine that all invariant mass (particles) always is coupled to a 'gravity', however weak it may be in a uniform motion, then we may agree. But using that definition we now have destroyed the idea of all uniform motions being equal (in a black room scenario)? I'm not sure there? Can one keep the definitions, the invariant mass was there before too, wasn't it? But in Einsteins universe gravity is a result of geometry, not 'forces' and 'quanta'? It's a hard nut to crack this one.
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And even then I have severe trouble seeing why the Higgs boson/field would threat uniform motion differently than a accelerating? How can it define the difference there, assuming that their 'speeds' are identical at some 'instant', they should be treated the same by the Higg mechanism, that is if we define them as 'clinging to motion'? I need to look this one up.
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Then you would have inertia as the invariant definition of a Higgs particle (relative rest mass), with 'gravity' as ? Potential? And thinking some more, it would also question the definition of all uniform motions being relative, as Einstein defined it. That as we now would have a universal frame acting upon us at all times. In Einsteins definition inertia has nothing to do with a uniform motion, only with the change of it into some acceleration/deceleration.
Title: what is Mass?
Post by: Mr. Data on 06/07/2011 23:35:21
Assume you are in a coma, also define it such as I do from 'locality', meaning that I'm the sole representation of this unique 'frame of reference' that psychologically follows me around, by me defined as the one invariant 'thing' that never changes consisting of a 'intrinsic' time experience and 'c'. Why would the translations of others fit the experienced 'time' I find when I wake up? If time can be defined as a 'psychological state'?

Of course it depend on how you define that state as 'psychological', but that's also where I find it hard to see.

As painfully as I want to answer this - I can only appeal to authority, that QM and genetic testing seems to imply an dependance on how our evolution plays a part if not the whole thing of why anything experiences a time-frame. I don't state this in a frivilous nature: If we experience time or any duration which can be called a frame of time, then there exists the gene capable of making that happen. If we had no sense of time (absent of the Suorachiasmatic Nucleus) then what theory of relativity would we readily assume, noting also that only a very small curvature has been noticed in the universe.
Title: what is Mass?
Post by: yor_on on 06/07/2011 23:41:29
You are introducing new terms here.
Now I will have to check up the Suorachiasmatic Nucleus too :)
Title: what is Mass?
Post by: yor_on on 06/07/2011 23:44:54
Okay, I see your idea. But even without that part of your brain present you will be born, and you will die. And even a rock grows old. It's a interesting concept though. In fact it fits my idea/description of light (radiation) being our ultimate clock very well.
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Maybe we are defining the concept of time differently?

I define it as durations, those durations have a beat defined from 'c'. And even though all living things may have cycles related to those durations, the 'beat' will still exist when those things die. And that's what I call the 'arrow of time' pointing in one direction, at least macroscopically.

You could also define it as 'times arrow' needing some 'processing ability' to get noticed, is that how you see it?
Title: what is Mass?
Post by: Mr. Data on 06/07/2011 23:57:38
Suprachiasmatic Nucleus which is the proper typing.
Title: what is Mass?
Post by: yor_on on 07/07/2011 00:08:44
Maybe I could see it locally as when I die I take reality with me. Half philosophical half reality. Because if I treat reality locally I'm free to define solely from the point of reality I know is true. And that can only be my own, it's only there I can prove that light always come at 'c'. So using that as a 'beat' I now have defined a situation in where all other descriptions of its propagation becomes doubtful as I compare them to mine observation of their situation. Locality is everything, sort of. But that would imply that I is the only one really here too :)

And you can do it, philosophically and logically you can draw that conclusion from 'frames of reference', if you by 'reality' craves that it always should be conceptually fitting to your own observations/descriptions. In Einsteins universe that isn't true though, and we need Lorentz transformations to define others descriptions of their clocks and positions as being what we see, observing them.
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Or it is true :)
But then we're deep into philosophical space.

Actually it's 'simplicity' that steer my decisions here, and my hopefully 'common sense'.
Otherwise I would soon find myself in a padded cell, I'm afraid :)