Sakurai: gravitational repulsion

[Manojg]

Hi,

I was reading Sakurai's "Invariance Principles and Elementary particles". In first chapter, second paragraph (page 3), there is a line "The analogous dimensionless constant that characterizes the gravitational repulsion between two protons is ...".

Any body likes to comment on this, why there is gravitational repulsion or this is just a typo.

Thanks,

 

[Manojg]

Any body home?

 

[Drakkith]

I'm not sure this helps, but I found this under Gravitational Coupling Constant on wikipedia:

The proton and the electron are stable and possesses a quantity of charge of the elementary charge e. Hence the ratio α/αG measures the relative strengths of the electrostatic vs. gravitational attraction/repulsion between these elementary particles.

Looks like it is talking about the repulsion from the electric charge, not gravity. But I haven't read Sakurai's book, so I don't really know.

 

[bcrowell]

Sounds like a typo to me. Maybe if you quoted more context, we'd be able to tell better.

 

[Creator]

Hi,
why there is gravitational repulsion or this is just a typo.

Thanks,

Hilbert describes a gravitational repulsion which is velocity dependent, IOWs, the gravitational interaction changes at relativistic (coordinate) velocities, reaching a repulsion at a critical velocity of c/ sq.rt(2)...
http://arxiv.org/PS_cache/arxiv/pdf/0904/0904.1578v1.pdf

So this seems like a reference to an application of Hilbert gravitational repulsion to sub-atomic particles which includes their charge.

Creator

 

[bcrowell]

Hilbert describes a gravitational repulsion which is velocity dependent, IOWs, the gravitational interaction changes at relativistic (coordinate) velocities, reaching a repulsion at a critical velocity of c/ sq.rt(2)...[...]

So this seems like a reference to an application of Hilbert gravitational repulsion to sub-atomic particles which includes their charge.

Loinger is a kook. The paper you linked to was not published in a peer-reviewed journal. Please review PF rules https://www.physicsforums.com/showthread.php?t=414380 , which state: "It is against our Posting Guidelines to discuss, in the PF forums or in blogs, new or non-mainstream theories or ideas that have not been published in professional peer-reviewed journals or are not part of current professional mainstream scientific discussion."

In any case, the repulsion would not occur in the case of two protons.

 

[Manojg]

Sounds like a typo to me. Maybe if you quoted more context, we'd be able to tell better.

Here are more lines:

"The various classes of fundamental interactions are characterized by coupling constants that differ in many orders of magnitude. The electromagnetic coupling is characterized by the well-known dimensionless constant 1/137. The analogous dimensionless constant that characterizes the gravitational repulsion between two protons is G^{2}_{grav} M^{2}_{p}/\hbar c = 2 \times 10^{-39}, which shows that we can essentially ignore gravity in discussing elementary particle phenomena.

 

[bcrowell]

OK, this is clearly just a typo. Instead of "gravitational repulsion," it should say "gravitational attraction."

 

[Manojg]

OK, this is clearly just a typo. Instead of "gravitational repulsion," it should say "gravitational attraction."

Thanks.