[CraigD]

An experiment to confirm that gravity is a boson-mediated force.

The Standard Model of particle physics has been, in terms of experimental verification, arguably the most successful significant scientific theory in history.

Yet, the “standard” Standard Model describes only 3 of the 4 fundamental forces – the electromagnetic, the strong nuclear, and the weak nuclear. Attempts to include the 4th force – gravity – have been troubled, failing to gain widespread acceptance of the proposed boson known as the graviton. This omission severely limits the formalism available for branches of Physics like cosmology, and generally leaves science professionals and amateurs with a sense of unease.

In a post to the “Speed of light is limited by what?” thread, Southtown suggested that a light clock is a faulty design for a clock for measuring time dilation, but that an analog wrist watch might not be.

My initial reaction to this was to point out that an analog wrist watch is as much a light clock as the kind to which the term normally refers. According to the Standard Model, all of the forces involved in the movement of a spring-driven, analog wrist watch result from interactions of bosons, primarily photons of magnetic force between electrons and the quarks that compose protons and electrons in its atoms, and between the electrons in the atomic lattices that comprise the macroscopic parts of the watch. The light clock thought experiment applies as much to this much more complicated arrangement as to the usual, simplified one.

It then occurred to me that there is a kind of clock that’s movement does not, according to the “standard” Standard Model, involve boson interaction: A pendulum clock, which, in addition to the usual bosons, depends on the gravitational force.

I wonder – is it possible, in principle if not within the limits of practical experimental precision, to falsify the hypothesis that the gravitational force is due to the graviton, by detecting that the gravitational force producing a pendulum clock’s movement does not exhibit relativistic time dilation?

PS: I seem to have posted this thread in the wrong forum. It should be in "Physics and Mathematics"

[UncleAl]

1) All force mediators are bosonic by definition. A fermionic force mediator would suffer Fermi exclusion and not degenerately sum.

2) If gravitation were quantized gravitons would be spin-2 tensor bosons not spin-1 vector bosons. You would need quadrupole rather than dipole selection rules.

3) Since General Relativity assumes h=0, it cannot be quantized. Since the Standard Model assumes G=0, it is not relevant to gravitation. There is no observational evidence that gravitation is quantized. The weakness of gravitation, G as coupling constant, makes such an observation beyond technology as we know it or can imagine it.

Relativistic time dilation derives from spacetime geometry. The presence of a physical clock (oscillator, radioactive decay, biological ageing) is irrelevant. For a hanging pendulum with small angular swing (sin(theta)~theta),

T_small = 2(pi)sqr([L/a)

where "T" is the period, "L" is the suspension length, and "a" is the local acceleration (gravitational or inertial or both). Note that the pendulum bob's mass does NOT appear. Your proposed experiment is specifically excluded by the Equivalence Principle, and that is a founding postulate of General Relativity.

If the angular swing is large you get

T_large = T_small[1 + (1/2^2)sin^2(theta/2) + (1/2^2)(3^2/4^2)sin^4(theta/2) +...]

http://www.iit.edu/~smile/weekly/mp020502.html
http://www.ux1.eiu.edu/~cfadd/1350/13Oscill/Pend.html

[Qfwfq]

Originally Posted by CraigD

I wonder – is it possible, in principle if not within the limits of practical experimental precision, to falsify the hypothesis that the gravitational force is due to the graviton, by detecting that the gravitational force producing a pendulum clock’s movement does not exhibit relativistic time dilation?

There would be no point in such an experiment. Time dilatation is due to the Lorentz coordinate transformations. It means that the time interval between two events is greater than the proper time, in the coordinates other than those for which the two events have the same spatial coordinates. Nothing to do with how the clock works.

[Southtown]

Even though the topic and replies are all way over my head, I think I understand the error of my original question. Thanks all for much brain food.

[Southtown]

I don't claim to know any answers, but it seems I've heard some news that may be relevent to gravity being a boson force.

“Total eclipses of the Sun by the Moon reach maximum eclipse about 40 seconds before the Sun and Moon's gravitational forces align. If gravity is a propagating force, this 3-body (Sun-Moon-Earth) test implies that gravity propagates at least 20 times faster than light.

The Earth accelerates toward a point 20 arc seconds in front of the visible Sun, where the Sun will appear to be in 8.3 minutes. Thus, the acceleration now is toward the true, instantaneous direction of the Sun now, and is not parallel to the direction of the arriving solar photons now.” — [The speed of gravity - what the experiments say. T. van Flandern, Physics Letters A. vol.250, no.1-3, Page: 1-11 (1998)] (alternate PDF document)

Found at this site from UncleAl: http://spacescience.spaceref.com/new...t12oct99_1.htm

[Southtown]

Originally Posted by CraigD

In a post to the “Speed of light is limited by what?” thread, Southtown suggested that a light clock is a faulty design for a clock for measuring time dilation, but that an analog wrist watch might not be.

Please, forgive my persistent ignorance. I can now understand how analog clocks would be just as distorted as light clocks. But how does the distortion of clocks require the equivalent dilation of time? Is time defined by clocks? It is measured that way, but is that proof that time itself dilates?

[Erasmus00]

Originally Posted by Southtown

Please, forgive my persistent ignorance. I can now understand how analog clocks would be just as distorted as light clocks. But how does the distortion of clocks require the equivalent dilation of time? Is time defined by clocks? It is measured that way, but is that proof that time itself dilates?

How else would you define time other then with a clock? You define distance with a ruler.
-Will

[Southtown]

Originally Posted by Erasmus00

How else would you define time other then with a clock? You define distance with a ruler.
-Will

No. That is merely how you quantify it. It exists outside of being measured.

[CraigD]

Originally Posted by Southtown

No. That is merely how you quantify it. It exists outside of being measured.

You're denying materialism, and affirming formalism (AKA "platonic realism").

Though this view is likely the healthier one, in human terms, it's not scientific.

[Erasmus00]

Originally Posted by Southtown

No. That is merely how you quantify it. It exists outside of being measured.

Yes, it exists, but it hasn't been fully defined. In science we deal with quantifications, deffinitions. All we can deal with are measurements, so its strange to say that just because the measurements dilate, the thing itself might not. We can never know that. All of what you know could be a reality, only the measurements your senses make change, everything else is static.
-Will