Can we make minus mass?

[alpha2cen]

Let us think about this case.

There is a vessel, which contains anti-hydrogen gas.

The balance indicates 1g.

In this case, can we state minus 1g?

Does this have any problem?

Edited January 18, 2011 by alpha2cen

[ajb]

How are you defining mass?

 

To our best knowledge matter and antimatter interact with gravity in the same way. This is a corollary of the equivalence principle. Thus, hydrogen and anti-hydrogen weigh the same.

 

It could be the case that the equivalence principle does not hold. Studying anti-hydrogen could provide a test of this.

[alpha2cen]

How are you defining mass?

 

To our best knowledge matter and antimatter interact with gravity in the same way. This is a corollary of the equivalence principle. Thus, hydrogen and anti-hydrogen weigh the same.

 

It could be the case that the equivalence principle does not hold. Studying anti-hydrogen could provide a test of this.

 

This means

Hydrogen----------- 1mol 1g

vacuum ------------ 1mol 0g

Anti-hydrogen -----1mol -1g

F= |m| g ?

quantum theory

Edited January 18, 2011 by alpha2cen

[ajb]

So, if [math]F = |m|g[/math] then weighing the anti-hydrogen would give the same weight as hydrogen, even if anti-hydrogen had negative mass.

 

You could say that the force law for anti-matter is different. Technically it would be a repulsive force for anti-matter. In particular we have

 

[math]- F = - m g[/math],

 

but what would be the difference to just saying anti-hydrogen has positive mass?

[alpha2cen]

but what would be the difference to just saying anti-hydrogen has positive mass?

When we write the anti-hydrogen mass as plus mass,

are there any trouble to calculate particle property on the quantum physics ?

At the annihilation reaction if anti particle mass were minus mass, it would be easy to represent.

i.e.

m(matter) + -m(anti-matter) = 0 mass

Annihilation reaction is different than normal nuclear fusion reaction.

Edited January 18, 2011 by alpha2cen

[swansont]

When we write the anti-hydrogen mass as plus mass,

are there any trouble to calculate particle property on the quantum physics ?

At the annihilation reaction if anti particle mass were minus mass, it would be easy to represent.

i.e.

m(matter) + -m(anti-matter) = 0 mass

Annihilation reaction is different than normal nuclear fusion reaction.

 

You violate conservation of energy. 0 mass cannot be the result of (or source of) converting other forms of energy.

[CaptainPanic]

[edit]

I've deleted the whole post because I think it was gibberish. Sorry if this is inconvenient (especially to alpha2cen who replied very quickly after my post).

Edited January 18, 2011 by CaptainPanic

[alpha2cen]

At the nuclear fusion reaction particle does not disappear.

But At the annihilation reaction particles disappear.

Can we consider two cases same?

[D H]

You need to specify what you mean by "mass", alpha. There is inertial mass, active gravitational mass, and passive gravitational mass. Newton implicitly assumed inertial and gravitational mass are one and the same. Einstein made this assumption explicit in the equivalence principle.

 

In terms of Newton's laws, inertial mass is the factor m in a = F/m; the mass term M in a=GM/r² represent active gravitational mass. I intentionally reformulated Newton's laws to hide passive gravitational mass. Newton's second law is F=ma; his law of universal gravitation is F=GmM/r². If inertial and passive gravitational mass are not the same, the m term in Newton's second law is inertial mass for non-gravitational forces but is passive gravitational mass for gravitational forces.

 

A particle and its antiparticle have the same inertial mass, both per theory and per experiment. Some very weird things would happen if the inertial mass of an antiparticle was negative. Suppose we place a charged particle and its antiparticle at rest with respect to one another. The particle with positive inertial mass would be repulsed by the other particle, but the particle with negative mass would be attracted to the other particle. The negative mass particle would chase the positive mass particle. We would see signs of this weird behavior in particle colliders if antiparticles had negative inertial mass. We don't see that behavior. Instead, we see behavior that is consistent with particles and antiparticles having the same (positive) inertial mass.

 

Determining whether antiparticles have negative passive gravitational mass is a bit harder to test. A number of experiments have been proposed recently based on the recent acquired ability to make cold anti-hydrogen. Note that these proposed experiments are not looking for negative mass (negative mass is a crackpot notion); they are instead looking for tiny violations of the equivalence principle.

[alpha2cen]

When anti-proton collides with neutron, does no annihilation reaction occur?

Edited January 18, 2011 by alpha2cen

[swansont]

When anti-proton collides with neutron, does no annihilation reaction occur?

 

No, they are not antiparticles of each other. What would happen to the proton's charge, for example, if one were to propose that it could happen?

[IM Egdall]

A particle and its antiparticle have the same inertial mass, both per theory and per experiment. Some very weird things would happen if the inertial mass of an antiparticle was negative. Suppose we place a charged particle and its antiparticle at rest with respect to one another. The particle with positive inertial mass would be repulsed by the other particle, but the particle with negative mass would be attracted to the other particle. The negative mass particle would chase the positive mass particle. We would see signs of this weird behavior in particle colliders if antiparticles had negative inertial mass. We don't see that behavior. Instead, we see behavior that is consistent with particles and antiparticles having the same (positive) inertial mass.

 

 

 

I am wondering about virtual particles. As I understand it, in the Feynman view of QM, a particle and its anti-particle appear out of the "vacuum", collide, and annihilate each other. This all happens fast enough for given particle mass/energies so that the Uncertainty Principle on energy versus time is obeyed.

 

But one virtual particle has positive energy and the other has negative energy. That's why there is no resultant energy produced (as oppossed to real particle-antiparticle collisions). So can we think of the particle with negative energy as having a negative mass per E=mc**2?

[Xittenn]

I do believe the highly theoretical Tachyon has a negative rest mass in some models but this leads to highly speculative discussions on what exactly that is ....

 

forgive my injection :|

[D H]

I am wondering about virtual particles.

 

(With the possible exception of Hawking radiation) virtual particles don't really count, do they? We can't detect virtual particles, and they don't obey [math]m^2c^4 = E^2-p^2c^2[/math]. Which of the virtual pair has negative mass, if you want to call it that, has nothing to do with which is the antiparticle.

 

I do believe the highly theoretical Tachyon has a negative rest mass in some models but this leads to highly speculative discussions on what exactly that is ....

Tachyons are better described as highly science fictional, rather than highly theoretical. However, they don't have negative mass. They have imaginary mass (the square of the mass is negative).

[lemur]

I think to call something anti-mass, it would have to be gravitationally repellant instead of attractive. I think it would also have to be endothermic when converted into energy. So, for example, if you could get two particles with anti-mass to fuse, the difference between the sum of the parts and the resulting particles would consume energy instead of releasing it. As I understand it, fusion among heavy elements is endothermic anyway, but I think the mass of the unified particle is greater than that of the daughter particles, so if those particles had anti-mass, fusing heavier particles could be exothermic as the daughter particles lose anti-mass in combining. Would the particles with anti-mass be repelled from each other, though, or would they only be repelled from particles with positive mass and be attracted to each other? Isn't this just dumb speculative meandering? What's the point of wondering what negative mass would or could be?

[swansont]

I think to call something anti-mass, it would have to be gravitationally repellant instead of attractive.

 

F = -GMm/r^2 would be repulsive, but what of F = ma? See ajb's earlier post.

[steevey]

Let us think about this case.

There is a vessel, which contains anti-hydrogen gas.

The balance indicates 1g.

In this case, can we state minus 1g?

Does this have any problem?

 

Just because some matter acts differently than normal matter doesn't mean it's NOT matter. Any "matter" has mass. Minus 1g would indicate that there is negative matter there, which something that is impossible in reality in the same as having negative distance.

Edited January 19, 2011 by steevey

[alpha2cen]

I am worried about this case. If in the future we found new particle which has mass 1 and minus charge, not anti-matter(similar particle is muon but it's mass is too low than proton), how could we describe two particles differently? Gravity or inert mass property is another problem, their property might proportional to absolute value |m|, my guessing, have we thought this problem seriously before?

Edited January 19, 2011 by alpha2cen

[steevey]

I am worried about this case. If in the future we found new particle which has mass 1 and minus charge, not anti-matter(similar particle is muon but it's mass is too low than proton), how could we describe two particles differently? Gravity or inert mass property is another problem, their property might proportional to absolute value |m|, my guessing, have we thought this problem seriously before?

 

If something has a minus charge though, doesn't that mean its charge simply negative? I mean quarks use 3 different charges already, and gluons are suppose to use 8. What's wrong with finding a particle with yet another charge even if that question above isn't what your saying?

Edited January 19, 2011 by steevey

[ajb]

I do believe the highly theoretical Tachyon has a negative rest mass in some models but this leads to highly speculative discussions on what exactly that is ....

 

forgive my injection :|

 

They have negative mass squared. They do not violate anything within special relativity, but quantum mechanically they are understood to be unstable and would quickly decay.

[lemur]

F = -GMm/r^2 would be repulsive, but what of F = ma? See ajb's earlier post.

-F = -mg is unclear to me. What is negative force? Is it anti-force or is it normal force where negative mass/matter is involved? Further why wouldn't negative mass have its own attractive force in addition to being repelled by positive gravity of positive mass/matter? Then wouldn't you have to have something like -F = mg (where -m and -g cancel each other out to become a positive)? But wouldn't you also have to have -F = -mg in relation to positive gravity's interaction with anti-mass matter? Further, what would anti-acceleration mean? Would it be acceleration in an anti-direction (i.e. some direction in anti-spacetime?). I think these "anti" concepts tend toward convolution. Wouldn't it make more sense to just create new names for things instead of referring to them as "anti" variations of existing things?

Edited January 19, 2011 by lemur

[alpha2cen]

Let us think about this case.

Three case of fusion

1)proton + proton-------------->2 proton + fusion energy

mass change 1 + 1------------->=~2

gravity effect 1+ 1 ------------>=~2

inertial mass 1+ 1------------->=~2

 

2)anti-proton + proton------------->0 + fusion energy

mass change -1 + 1---------------->0

gravity effect |-1|+ 1 -------------->0

inertial mass |-1|+ 1--------------->0

 

3) anti-proton + anti-proton--------> 2 anti-proton + fusion energy

mass change -1 + -1------------------>=~ -2

gravity effect |-1|+ |-1| -------------->=~ |-2|

inertial mass |-1|+ |-1|--------------->=~|-2|

 

Good point is anti-proton.....neutron....electron.....positron...etc., combined fusion calculation is easy.

[D H]

alpha2cen, while your diagrams might make sense to you, they are more than a bit nonsensical. You have already been told that anti-protons have the same mass as protons.

[swansont]

A negative sign in a vector equation tells you the direction of the vector. So F = ma with a negative mass tells you force and acceleration are in the opposite direction. So you have a situation where gravitational mass and inertial mass are not the same thing.

[alpha2cen]

How about we call it inherent mass or primal mass?

 

Inherent mass

proton 1

anti-proton -1

 

mass

proton 1

anti-proton 1

 

the relation mass and inherent mass

m_mass = |m_inherent|

I think this relation would be easily proved without trouble.

 

Are there any problems?

Edited January 20, 2011 by alpha2cen