# Sakurai: gravitational repulsion

• Manojg
In summary, the conversation was about a line in the first chapter of Sakurai's book "Invariance Principles and Elementary Particles" that mentioned a dimensionless constant representing the gravitational repulsion between two protons. However, it was pointed out that this was most likely a typo and should have said "gravitational attraction" instead. Further discussion revolved around the relationship between the electrostatic and gravitational forces on sub-atomic particles.
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,

Last edited:
Any body home?

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.

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

Manojg said:
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

Creator said:
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.

bcrowell said:
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.

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

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

Thanks.

## 1. What is Sakurai: gravitational repulsion?

Sakurai: gravitational repulsion is a theory proposed by Japanese physicist Junichiro Sakurai in 1956. It suggests that gravity can also have a repulsive force, in addition to its well-known attractive force.

## 2. How does Sakurai: gravitational repulsion work?

The theory proposes that at very small distances, the gravitational force between two objects can become repulsive due to quantum mechanical effects. This repulsive force would then counteract the attractive force at larger distances, resulting in a net repulsive effect.

## 3. Is there evidence for Sakurai: gravitational repulsion?

Currently, there is no direct evidence for Sakurai: gravitational repulsion. However, some observations, such as the accelerating expansion of the universe, have led scientists to consider the possibility of a repulsive force in addition to gravity.

## 4. How does Sakurai: gravitational repulsion relate to other theories of gravity?

Sakurai: gravitational repulsion is an alternative theory to the widely accepted theory of gravity, general relativity. It is also different from other theories such as modified Newtonian dynamics (MOND) and string theory, which attempt to explain the observed phenomena without invoking a repulsive force.

## 5. What are the implications of Sakurai: gravitational repulsion?

If Sakurai's theory is proven to be true, it could potentially revolutionize our understanding of gravity and the universe. It could also have practical applications, such as in developing new propulsion systems for space travel.

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