Gravitation Anomaly Measured 540
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."
3rd body problem? (Score:5, Interesting)
Re:Anomaly in Gravity During Sun Eclipses? (Score:2, Interesting)
Nope, exactly the opposite.
Not to mention that the article suggests that the effect occurred just as the alignment took place, not slightly before or after, when the summed effects of the Sun and Moon's gravity should have been nearly the same as during the alignment.
Re:3rd body problem? (Score:3, Interesting)
Nevertheless, for solar system dynamics, this is irrelevant. Newtonian gravity works quite well, and even if you did need to go to relativistic corrections, you can do that within the perturbation scheme of linearized gravity to more than sufficient accuracy.
Re:3rd body problem? (Score:2, Interesting)
One possible explanation (Score:1, Interesting)
- Photons have mass.
- An eclipse means less photons are emitted and reach the measurer.
- Ergo, gravitational effect.
Although it is well known that if your effect has a name it instantly has more credibility, I'm a bit skeptical that this is the one that'll turn relativity on its ear (dark matter is another story...)Re:3rd body problem? (Score:3, Interesting)
On the other hand, you can calculate a solution to the three-body problem to any level of accuracy that you are interested in, without much effort. Yes, it's an approximation, but so is any calculation.
Thad
Einstein would not be surprised (Score:5, Interesting)
Testing theories is a very thankless task, because nature never says "yes." Usually nature says "no," meaning that a measurement contradicts a theories predictions.
Sometimes, nature says, "maybe," indicating that while the measurements are consistent with the theory.
But nature never says "yes," because your theory could be incomplete or erroneous but your instruments are either too inaccurate to detect the error, or you are not doing the right experiment.
Newtonian dynamics makes good enough predictions for alot of phenomena.
General Relativity is more precise in its predictions.
Given our difficulties in unifying it with quantum mechanics, it is likely that we don't have the right theory. As our instruments get more precise and we conduct more experiments, eentually we'll get a hint as to where we are going wrong.
Good reason for a mission to the Moon (Score:5, Interesting)
For real confirmation, an experiment on one of the Jovian moons would do nicely.
Yes, I'm serious about this. This is fundamental to our understanding of physics, which is in turn fundamental to our understanding of the origins, processes and fate of the universe. A billion to put a pendulum on the Moon would be money well spent.
Re:3rd body problem? (Score:3, Interesting)
Re:One possible explanation (Score:5, Interesting)
As I recall, MOND solves some of the more annoying problems of astronomy: missing matter, and the apparent need for a period of faster-than-light expansion early in the history of the universe.
Possible explanation (Score:4, Interesting)
Could this be constructive interference caused by the collision of the gravity wavefronts from the sun and the moon when they are lined up just right?
Just a thought, the real explanation is probably much crazier.
Re:One possible explanation (Score:1, Interesting)
This is why gravity affects them
Photons do not have rest mass.
could it possibly... (Score:1, Interesting)
Re:Anomaly in Gravity During Sun Eclipses? (Score:3, Interesting)
From Chris Duif's paper: (Score:5, Interesting)
And here's a point not covered in the paper: if these experimental effects occur when the moon is between the pendulum and the sun, then shouldn't they also occur every time the earth is between the pendulum and the sun...say, every night? If this effect is due to a large mass's ability to block gravity, then surely someone should have detected this effect from the earth blocking the sun's gravity by now!
On the other hand, if the effect is because moon cheese acts as a form of Cavorite [wikipedia.org], well, then I can't help you with that.
Re:Anomaly in Gravity During Sun Eclipses? (Score:2, Interesting)
As I read it, we are talking about a very subtle change caused by massive objects lining up in space (moon/sun). If there is indeed a change in gravity, then yes, our satellites would be causing it to some small degree as well, but considering the difference in mass between a man-made satellite and the moon, I suspect we do not have the instruments to measure it.
Re:Possible explanation (Score:2, Interesting)
Re:Anomaly in Gravity During Sun Eclipses? (Score:5, Interesting)
To answer your question, the effect, if it exists, hasn't been noticed because there are many other perturbing effects on the orbit. The most important, by decreasing magnitude, are: earth's gravitational attraction, moon attraction, oblateness of the earth (that is, the flattening at the poles), sun gravitational attraction, solar radiation pressure, tri-axiality of the earth (that is, the east-west irregularity in the gravitational attraction), albedo (that is, the pressure exerted by the sunlight reflected by the earth), dynamic solid tide (the gravitational effect of the earth's deformation caused by the moon's attraction), gravitational attraction by venus, gravitational attraction by jupiter, relativistic effects caused by the earth's gravitation.
So, you can see that there are so many other effects that it's pretty hard to separate each one. In particular, the effects of solar radiation and albedo change more or less randomly, so in the end, whatever cannot be explained otherwise in a satellite's orbit is normally attributed to "solar radiation".
It's only when a probe goes so far from the sun as Pluto that solar radiation becomes small enough for other perturbations to be measured.
Mobious strip (Score:2, Interesting)
The univese might be shaped like a klien bottle and be both inside of itself and outside of itself in terms of time. Help I'm stuck in a loop - help I'm stuck in a loop.
Just some zany ideas.
Laters
Just a Crazy idea (Score:2, Interesting)
AcrazyPhysicsPoet
Gravitational Anomalies in Greece (Score:4, Interesting)
For example, you put your car in neutral in the outskirts of the mountain and instead of gravity to pull it down, it is tractored upside. Expert physicists claim there is another energy in the mountain area that is more powerful than the gravity itself, thus creating the effect.
NATO was interested (and presumambly is still) in that particular area. It's part of Greece's x-files
Re:If gravity is blocked by mass, then... (Score:5, Interesting)
I see no discussion in the article of the fact that the moon distorts the space around it so that when it is between us and the sun we are slightly further away from the sun than when it is not in line. This effect has to be incredibly small but it appears the allais effect, if it exists at all, is quite small, so perhaps this is the cause. Somebody should at least calculate it out.
I have seen this theory that they mention about gravity being less effective when weak. The usually more reliable Scientific American allowed an article on it to sneak in some months ago.
Its a very silly idea because it breaks the principle of equivalence - you can now tell if you are in an elevator or a gravitational field by bringing a mass close to a test mass to almost cancel out the field and observing whether or not you see the weak gravity effect.
This in turn means physics is not covariant and that there are preferred frames of reference. So its not a "small adjustment" but a total do-over of physics.
Re:3rd body problem? (Score:3, Interesting)
Re:Anomaly in Gravity During Sun Eclipses? (Score:5, Interesting)
(one facing the object, and the other on the opposite side). These lead to diurnal (24 hour cycle) and semi-diurnal (12 hour cycle) tides.
When the Moon and Sun are aligned together, you have Spring tides. Neap tides are caused when th e Moon and Sun are perpendicular to one another. There is also the Proxigean Spring Tide, when the moon is at its closest point to the Earth (perigee). This time is known as the "proxigee", and causes even higher tides than ordinary Spring Tides. Fortunately, these only occur once every 1.5 years.
The gravitational acceleration at the Earth's surface is 9.8 metres/second per second (towards the centre of the Earth).
The gravitational acceleration on Earth due to the Sun is 0.0059 metres/second per second.
Or about 5.9 millimetres/second.
The gravitational acceleration on Earth due to the Moon is 0.000033 metres/second per second.
Or about 0.033 millimetres/second.
Source: Space Talk Forum [space-talk.com]
These amounts are small, but research groups at one of the particle accelerator rings actually noticed a distortion in the targeting of the beams due to the stretching/squashing of the surrounding land caused by the changing positions of the Sun and Moon. This caused the beam to periodically go off target.
Intuitively, one would assume that gravity would be less when the Sun and Moon were overhead, and the pendulum would swing slightly higher and slower. Plus the behavior of the pendulum should vary according to the positions of the Sun and Moon.
If the "shielding effect" occurred with large objects, then it would also apply to Earth's ocean tides. The closest side of the Earth one should shield the opposite side, but the bulging effect can be explained by simple vector addition/subtraction [uoregon.edu].
Re:If gravity is blocked by mass, then... (Score:3, Interesting)
With sufficiantly accurate measurment devices (which we don't happen to have), you should be able to tell the difference between an elevator or a gravitational field anyways. Why? Gravity is a field. Therefore the force at your head is ever so slightly less than the force at your feet, theoretically. With an elevator, the force is the same throughout your body.
So, it seems you have a problem there anyways.
Dark whatever... (Score:2, Interesting)
I learned in an Astronomy course in the mid-90's that astronomers noticed that the universe has 10 times more mass than what is visibly detectable because of observations of movements due to gravity. I think they noticed this in relation to galaxies as well as globular clusters. The remaining 90% was dark matter, or dark matter and dark energy or something they just couldn't detect. Could this Allais effect be an alternative explanation for that missing 90%?
Okay, I don't know shit about physics except some of the real basics. But I want to blab anyway. From what I gather, they say it's supposed to be all connected. Energy is related to mass and the speed of light (E=mc^2). Mass is related to gravity, more mass more gravity (Jupiter). Mass and velocity are related to time, time slows as you approach the speed of light, mass increases. Energy moves at the speed of light. Mass is infinite for matter moving at the speed of light. And there are formulas that connect them all. Yay. I suppose the relation of mass, velocity, and the speed of light looks kind of like the graph of y=1/(x^2), where x is velocity and y is mass; x<0 are tardyons, x=0 is the speed of light, x>0 are tachyons. Okay, so I think I got that much. Now about gravity- does the effect of gravity happen instantaneously like quantum entanglement? For example, if the sun was moved, would all the planets instantly alter their orbits, or would the effect on their orbits have a delayed effect that would reach them at the speed of light because of something like gravitons? Does quantum entanglement mean that the entangled particles, at some wierd mathematically inversed level, are the same point? Someone give it to me in layman's terms so I don't get a nosebleed.
Einstein is safe (Score:5, Interesting)
Seems to me like the effect is most likely due to someone walking their dog a couple blocks away.
More interesting is how everyone wants to prove that Einstein's theory is wrong. Seems to me like a bit of brain-envy.
Nice try, but this article only goes about 0.5*10^-10 of the way to convincing me the chuck the field equations.
Re:Or a couple million for an improved expt on ear (Score:2, Interesting)
Re:Einstein would not be surprised (Score:2, Interesting)
Before we invent any of that stuff, we need to figure out a way to prevent even one person from being insane enough to use these high-energy, space-bending, mass-moving devices in an irresponsabla manner.
Nuclear weapons are scary enough, but you have to have a large number of people conspiring to produce and use them. Sanity has, thus far, prevailed.
Give Joe Sixpack the ability to harvest sub-etha superbosons and create a kg of antimatter, and that's all she wrote.
Gravitational Directionality (Score:2, Interesting)
There are two possibilities which immediately come to mind. Does anyone know of research about these:
Another reminder (Score:3, Interesting)
Mys-TEER-i-ous things (with waggling fingers)...
Not shielding, a new horizontal force possibly. (Score:3, Interesting)
Most of the posts are supposing the physicists doing this are real dumb. That in itself, is stupid. I think one or two have interesting points (e.g. "Einstein is Saf e") and most of the others are way off base. The paper is a summary of research by other people. The problem being discussed was noticed by Allais 50 years ago when he ran a month long pendulum experiment (three drops per minute I believe) that happened to intersect the time of an eclipse. The paper goes over a number of possible reasons for error and includes some as yet unpublished data on experiments intended to uncover them. The possibilities are c reative and followed up scientifically, for example one is done in remote China with nobody within 200 meters. All tests showed the suggested errors to be miniscule, although the paper does suggest that a combination of them might just cover it.
It would appear that a significant anomaly has been detected by various experiments and that professional scientists are taking it much more seriously than say cold fusion. It also is clear that there is a lot still to learn about gravity and that NASA is one of the groups that is working hard to figure out why its space probes don't move as expected. Some people even think gravity moves 20 times faster than light and other stories. It is not a shut case yet. In the paper mentioned in the post, they are saying that most people couldn't in the past solve the problem because they were thinking in terms of the Moon "shielding" the Earth from gravity, which the paper does not believe. They think it is more like an extra horizontal force that sometimes occurs during eclipses (of which there are different kinds including variations of angles). So all the posts about shielding are off base.
NASA has suggested that if experimental error really can't be the culprit, it might be caused by the same thing that apparently is accelerating Voyager more than expected.
I'd like to quote from a NASA article on the people who built Gravity Probe B [gravityprobeb.com].
I think that is cool. It says to me we have a good chance about learning a lot more about gravity and lots of other fundamental physics in the near to medium term future.
The paper also notes that one more individual experiment will not solve it; many simultaneous and comprehensive experiements are needed over the next few eclipses. It also suggests that it might be interesting to investigate "gravitational lensing by relativistic dark matter" although I cannot tell if that suggests we are in the midst of a river of high speed dark matter or what, something invisible passing between the Earth and Moon? Somebody with astrophysics degree please finally step in. Sounds like it might be interesting to have the ISS get involved too!
Links:
NASA decrypting the eclipse ('99) [nasa.gov]
Gravitational Anomalies - Literature List [space-time.info]
In Search of Gravitomagnetism (NASA Gravity Probe B) [nasa.gov]
Re:Nope... (Score:3, Interesting)
Google it. [google.com]
As I'm sure you know, even in a pure zero-energy vaccum space is not empty. The vacuum is actually filled with a seething sea of vacuum fluctuations and virtual particles. In between conducting plates the Casimir effect supresses some of those vacuum fluctuations and virtual particles. It is a region of negative energy space. A negative energy space is even more empty than an ordinary perfect vacuum. With fewer fluctuations and fewer virtual particles light is able traverse the space *slightly* faster than normal C.
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