Dark matter and energy explained by negative mass

[rootone]

I think that the concept of a negative mass is silly.
By analogy, a velocity of less than zero is silly.

 

[cosmik debris]

I think that the concept of a negative mass is silly.
By analogy, a velocity of less than zero is silly.

You mean like -10 km/s ?

Cheers

 

[PeterDonis]

By analogy, a velocity of less than zero is silly.

Not if you take direction into account.

If you mean a magnitude of velocity less than zero is silly, that's true.

 

[PeterDonis]

An Earth and a negative Earth-mass object so close they are nearly touching for a year will reach relativistic speeds (1g x 1 year is roughly the speed of light).

If they are both also Earth sized, yes.

 

[PeterDonis]

the artificial, delicately balanced "runaway" situation is completely irrelevant to cosmic rays as stands, and Franes should have realized this if that is what he meant.

It sounds like you are going for the option that I described here:

If the bound is too low, then Farnes's model predicts that such pairs can never produce a positive mass particle with high enough kinetic energy to account for cosmic rays at all.

 

[Buzz Bloom]

For velocities to rise indefinitely, it would be necessary for the masses to be perfectly matched and the particles to have exactly zero initial relative velocity, so it simply would not occur naturally.

Hi Elroch:

I do not understand the above quote. I wonder if you would please explain in some detail what would happen if there were a +mass particle near a -mass particle, and the initial conditions are that relative to the center of mass, the velocity vectors of these two particles have the same magnitude and opposite directions. Note that the initial relative velocities are not zero. I do not have the skills to do the math with any confidence that I will not make mistakes, but intuitively it seems that if the two particles initially are moving towards each other, then the results would be that particles would follow each other at an accelerating speed which eventually would overwhelm the initial velocity.

Regards,
Buzz

 

[Elroch]

Hi Elroch:

I do not understand the above quote. I wonder if you would please explain in some detail what would happen if there were a +mass particle near a -mass particle, and the initial conditions are that relative to the center of mass, the velocity vectors of these two particles have the same magnitude and opposite directions. Note that the initial relative velocities are not zero. I do not have the skills to do the math with any confidence that I will not make mistakes, but intuitively it seems that if the two particles initially are moving towards each other, then the results would be that particles would follow each other at an accelerating speed which eventually would overwhelm the initial velocity.

Regards,
Buzz

Well, both particles accelerate in the direction of the positive mass particle but, if the masses are equal, their relative velocity remains constant. So, given your description, they get further apart. The distance between them is thus O(time) and the interaction forces and the accelerations are O(time^-2). So the velocities are asymptotically constant (the integral of an inverse square is bounded), as is also true for two positive masses that are not bound together (For anyone not familiar with the terminology, google "big O notation" and "asymptotic").

 

[Buzz Bloom]

Well, both particles accelerate in the direction of the positive mass particle but, if the masses are equal, their relative velocity remains constant. So, given your description, they get further apart. The distance between them is thus O(time) and the interaction forces and the accelerations are O(time-2). So the velocities are asymptotically constant

Hi Elroch:

Thank you for your response to my question. I think the last part of the above quote from your post refers only to relative velocity V_r, and does not include velocity V₀ relative to the original center or mass. If I understand your explanation correctly,

|V₀| = |V_r| + F(t)​

Where F(t) is the increase in velocity due to the accelerations imparted to the each mass by the other mass. F(t) monotonically increases, but the rate of increase decreases as the particles becomes further apart and the acceleration decreases. Now, I understand F(t) is more complicated than a Newtonian calculation due to SR effects. If all this is correct, then I have an additional question.

The increase in |V₀| implies an increase in kinetic energy, which might also be described as an increase in mass-energy. Question: Isn't this increase a violation of the conservation law regarding mass-energy? If so, doesn't this violation imply that the Farnes speculative idea fails to be a reasonable way to think about the physics?

Regards,
Buzz

 

[rootone]

Not if you take direction into account.

If you mean a magnitude of velocity less than zero is silly, that's true.

Yes. but mass doesn't have a direction.
Now that would be really weird.

 

[exmarine]

I have a simple question about Farnes’ paper that I have seen in any of the responses. Hope I didn’t miss it.
How could the negative mass “haloes” collect or group around galaxies if, as his figure 1 shows, there is no attraction (i,e., inward acceleration) between negative and positive mass? It seems that negative mass would tend to distribute itself uniformly throughout the universe?

 

[Elroch]

If the net mass is positive, all the masses (both negative and positive) would gravitate towards the centre of mass, at which point you can imagine the (positive) total net mass existing. While this is an imprecise description, I think it might clarify the issue.

 

[exmarine]

But. . . Well I guess I see your point. The positive masses coalesce, negative masses do not. Thus any encounter between the two is un-symmetric, with the smaller negative accelerating towards the larger positive. Thanks.