Gravitation Anomaly Measured

Rob Riggs writes "Is there a hole in Einstein's Theory of Relativity? A story in The Economist talks about an apparent gravitation anomaly recorded during solar eclipses. According to Chris Duif at the Delft University of Technology, the 'Allais effect' is real, unexplained, and could be linked to another anomaly involving a the Pioneer spacecraft. More detailed information can be found in the paper he has just posted on arXiv.org."

Comments

Anomaly in Gravity During Sun Eclipses?

[RAMMS EIN]

You mean that the sun and the moon together pull stronger than the sun alone?

Re:Anomaly in Gravity During Sun Eclipses?

[LMCBoy]

No, the solar eclipse just allows you to measure the positions of stars which are very close to the Sun in the sky. Light from these stars is bent as it passes the Sun on its way to the Earth, due to the Sun's gravitational field.

Ironically, this was hailed as a proof of Einstein's relativity in the early 20th century, since the angle of deflection observed is much closer to the relativistic prediction, than to the Newtonian prediction.

Re:Anomaly in Gravity During Sun Eclipses?

[Ancient_Hacker]

Havent we had objects in orbit for 40+ yrs now, many positioned in just the right orbits to transit thru the moon's shadow? Satellites like the GPS series, whose positions are known and tracked to the centimeter?

Why hasnt this effect, if it exists, been noticed 1000's of times?

Re:Anomaly in Gravity During Sun Eclipses?

[Allaran]

Just because they are pulling in different directions doesn't mean they aren't having an effect. I believe it's just a sum of their effects (some effects being negative of course).

Re:Anomaly in Gravity During Sun Eclipses?

[IsaacW]

Well, some attempts to explain gravity with quantum mechanics theorize the existence of a fundamental particle called the graviton. The graviton would be the force carrying particle for gravity, just as the photon is the force carrying particle for the electromagnetic force.

If the graviton exists, then it might be possible that they are not transmitted well through all types of matter and so could be blocked on their way from one object to another. This could explain the anomaly.

The Economist?

[raider_red]

Why is this being carried in the Economist? Shouldn't it be picked up by New Scientist or some other scientific (or pseudo-scientific) publication?

Re:The Economist?

[dustmite]

Which in my mind only casts doubt on its existance.

Indeed. An economist making a valuable contribution to science ... that's almost as absurd as, oh, I don't know, a patent clerk making a valuable contribution to science.

Re:Einstein would not be surprised

[Ignignot]

Exactly. There are almost certainly missing elements in the model for gravity, for quantum mechanics, and so on. Maybe sometime in the future someone will come up with a quantum - relativistic super duper theory that brings disparate theories together. Yes, some of that is what string theory is trying to do. In the end though, it is going to take a LOOONG time before advances in science can be applied to engineering. Finding new particles, finding dark matter, and finding where missing socks go have no real life application right now - and I can't even imagine one. Just as math was (and still is) far ahead of where science can go, science is far ahead of where engineering can go. The missing elements of models would be useful for abstract knowledge, but have no practical use right now or probably in the next century.

Re:Good reason for a mission to the Moon

[visc]

Or, you could just do the test here on earth at night. Then the whole mass of the earth is between your apparatus and the sun.

I guess the reason that doesn't work is that thermal effects (like those that may be causing the Allais results) change everything at night, and it's too hard to distinguish a legitimate anomaly from some-thermal-effect-we-didn't-think-of.

Still, there's no need to go to Jupiter or even the moon; as a satellite in a higher and higher earth orbit checks the effect, the earth effects will drop off as 1/r^2 while the anomaly should remain constant.

If gravity is blocked by mass, then...

[Louis Savain]

If gravity is (very slightly) blocked by mass, then one would expect to have a different weight on the dark side of the earth than on the light side. It this observed? After all, if you're on the dark side, the entire mass of the earth should be shielding you (ever so slightly) from the gravitational pull of the sun.

Re:I know!

[n6mod]

Makes perfect sense.

All they're saying is that if 'g' were of the magnitude of this effect, then it would take a day for an apple to fall from a tree.

d=0.5*g*t^2

Pick a reasonable height for a tree, use 1 day for t, and solve for g.

Roughly, we're talking about something on the order of 10e-9 m/s^2

If gravity is blocked by mass.

[DM9290]

If gravity is blocked by mass, it would be a simple thing to simply observe a pendulum at night time and compare that to daytime.
The earth would block much more solar gravity than the puny little moon.

Then again, we would need a pendulum which is attracted to solar gravity because every pendulum on earth which swings, is doing so because of the gravitational attraction of the Earth.

Pay attention... pendulums on earth fall towards the EARTH, NOT THE SUN.

And another thing:

if you allow a pendulum to swing freely for 24 hours, the reason its path will trace out a circle, is *because of inertia* and the earth is rotating. THE PENDULUM IS NOT SWINGING TOWARDS THE SUN'S GRAVITATIONAL FIELD.

Are there any economists here who can explain this more clearly?

Re:From Chris Duif's paper:

[argent]

shouldn't they also occur every time the earth is between the pendulum and the sun...say, every night

Problem is, there is a known effect that would change the gravitation acceleration on an object as the Earth's orientation changes with respect to the sun. During the lunar eclipse, though, there's very little change in the relative positions and orientation of the earth, the moon and the sun.

That is, I suspect it would be too hard to distinguish between any such Allias Effect from the Earth and solar (and in this case, lunar) tides.

Re:3rd body problem?

[jbrandon]

That's a load of bullshit. Just because two problems are hard doesn't mean they're equivalent. I challenge you to give one reference about the equivalence of the three body problem and the halting problem.

Re:Gravitational Anomalies in Greece

[uptownguy]

Well, in Penteli mountain, there are verified gravitational anomalies (there are also a hell lot more noted in the Hellenic space by physicists).


Who mods this crap up? "NATO was interested" and "gravitational anomalies"?!? WTF!? I thought we were nerds here...

"Gravity hills" are nothing more than optical illusions, Penteli mountain included. Check out this link for more information. (shakes head at the state of "science" here on Slashdot... double shakes at the tin foil hat wearing mods...)