Will GR ever explain the flyby anomaly?

[kmarinas86]

A local velocity-dependence of local curvature of space would violate the notion that space is given a curvature only by surrounding matter. Any arbitrary test particle or object moving at some velocity isn't going to experience a different gravitational "force" under the same curvature conditions. The predictions of GR are equivalent to saying that if the flyby anomaly is a real phenomenon, then GR is falsified. When is this going to be picked up? I'm waiting for you, science.

 

[bcrowell]

If the flyby anomaly is real, then it falsifies GR. GR would have to be modified. That would be an extraordinarily exciting discovery.

The trouble is that the flyby anomaly almost certainly isn't real. If there was a consensus among physicists that there was a significant probability that it was real, the sane thing to do would be to launch special-purpose probes to test it that would be designed so as to be immune to as many systematic errors as possible. The results would almost certainly be null, but a positive result would be super-exciting.

This is similar to the Pioneer anomaly, which we now know was bogus ( http://arxiv.org/abs/0912.2947 http://arxiv.org/abs/1103.5222 ). We could have spent hundreds of millions of dollars launching special-purpose probes into the outer solar system. Instead, we avoided spending the pile of money and waited a couple of decades, and the anomaly was resolved. That's a better outcome.

 

[atyy]

I haven't read this http://arxiv.org/abs/1104.3985 . Do they agree with Francisco et al?

 

[bcrowell]

I haven't read this http://arxiv.org/abs/1104.3985 . Do they agree with Francisco et al?

Thanks for pointing me to the reference. I haven't read it yet, but the abstract says, "The analysis outlines that thermal recoil pressure is not the cause of the Rosetta flyby anomaly but likely resolves the anomalous acceleration observed for Pioneer 10." This would seem to indicate agreement between two independent groups about the thermal origin of the Pioneer anomaly.

 

[Neandethal00]

If the flyby anomaly is real, then it falsifies GR. GR would have to be modified. That would be an extraordinarily exciting discovery.

This is similar to the Pioneer anomaly, which we now know was bogus ( http://arxiv.org/abs/0912.2947 http://arxiv.org/abs/1103.5222 ). We could have spent hundreds of millions of dollars launching special-purpose probes into the outer solar system. Instead, we avoided spending the pile of money and waited a couple of decades, and the anomaly was resolved. That's a better outcome.

If thermal modelling is the best thing since slice bread, why don't they also apply thermal modeling to explain accelerating far away galaxies or even accelerated expanding universe? The universe is filled with heat/light or electromagnetic waves of almost infinite frequencies.

That will also save billions of dollars over the years searching for dark matters and dark energies.

 

[PAllen]

If thermal modelling is the best thing since slice bread, why don't they also apply thermal modeling to explain accelerating far away galaxies or even accelerated expanding universe? The universe is filled with heat/light or electromagnetic waves of almost infinite frequencies.

That will also save billions of dollars over the years searching for dark matters and dark energies.

Such effects are considered in cosmological modeling. I will resist any comments related to you nom de site.

 

[kmarinas86]

This is similar to the Pioneer anomaly, which we now know was bogus ( http://arxiv.org/abs/0912.2947 http://arxiv.org/abs/1103.5222 ). We could have spent hundreds of millions of dollars launching special-purpose probes into the outer solar system. Instead, we avoided spending the pile of money and waited a couple of decades, and the anomaly was resolved. That's a better outcome.

The problem with this statement is that we are talking about an anomaly on a totally different order of magnitude:

January 1998 | Near Earth Asteroid Rendezvous (NEAR) | 13.46 mm/s
August 1999 | Cassini-Huygens | ~0.11 mm/s
March 2005 | Rosetta | 1.82 mm/s

Here, we are talking about gravitational assists during Earth flybys. Probes at these speeds pass by the Earth in mere hours, but the Pioneer anomaly would require a whole week to build up such an anomaly. Also, there are many more probes in which this effect was observed - enough even to plot at least three correlation functions (1) J.D. Anderson 2) J.P. Mbelek 3) J.H. Busack).

It seems that your contention that the flyby anomaly is something you can compare to the Pioneer Anomaly is driven by scientific conservatism rather than an having an interest in obtaining a scientific measurement of this effect anytime in the future.

Also, the flyby anomaly is much less costly to test in any case, and so raising doubts about its existence by raising an issue about the implied costs of a "Pioneer anomaly"-focused experiment is a non-starter. Yet, somehow the fact that the Pioneer probes were ridiculously expensive to design and launch, together with the new explanation for the Pioneer anomaly, causes you to think that the flyby anomaly must somehow be explained along with it. Weird conclusion.

 

[PAllen]

There is no conspiracy here. in fact, if someone found a modification of GR that preserved existing findings, explained the flyby, and led to some well defined test to further verify the effect, a Nobel prize is there for the taking. Plenty of work has been done, no conclusion yet, that's all. If you have suggested alternate theory of gravity, publish it to your great glory.

Examples showing the effect is taken seriously, and much analysis done to characterize and explain it are shown in the links below. Note that in the second link, it is noted that all modifications to GR proposed so far to explain this either:

1) fail to explain it
2) explain it, but then fail to explain many other observations known
with greater confidence.

Simply put, this is an open question, being looked at from many points of view (by the scientists you scorn in your post). You are encouraged to offer a constructive contribution.

http://phys-merger.physik.unibas.ch/~aste/flyby.pdf
http://www.zarm.uni-bremen.de/fileadmin/images/laemmerzahlDatei/Pioneer_Utrecht.pdf

 

[kmarinas86]

For the record, I did not scorn the scientists which I mentioned in my post. But rather, I admire their efforts to put forth their own empirical equations for the flyby anomaly.

 

[PAllen]

The predictions of GR are equivalent to saying that if the flyby anomaly is a real phenomenon, then GR is falsified. When is this going to be picked up? I'm waiting for you, science.

This is scorn of the scientific enterprise. However, the reality is that scientists are investigating this from many points of view.

 

[kmarinas86]

For the record, I did not scorn the scientists which I mentioned in my [most recent] post. But rather, I admire their efforts to put forth their own empirical equations for the flyby anomaly.

Correction to quote added in brackets.

The predictions of GR are equivalent to saying that if the flyby anomaly is a real phenomenon, then GR is falsified. When is this going to be picked up? I'm waiting for you, science.

This is scorn of the scientific enterprise. However, the reality is that scientists are investigating this from many points of view.

Earlier, I thought you were speaking of the short list I presented in my most recent post here:

(1) J.D. Anderson 2) J.P. Mbelek 3) J.H. Busack

When people say experiments to test the flyby anomaly might not even be worth it, it makes me feel sometimes that my disenchantment of this part of science is justified. I don't think success of science should be enslaved to the inertia of the "trendy" areas of physics. I just wished more effort could be placed on this sort of thing (the flyby anomaly) before people jumped onto wild fantasies such as "theories of everything". It seems that experiments tend to be lacking relative to our imaginations.

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Anyway, thank you for clarifying that. I misunderstood you.

 

[Uglybb]

Can I also say that we are expecting GR to fail at some point because of quantum physics and a new theory is expected which incorporates both.

For the moment it is far more useful than Newtonian or any other theory out there.

No scientists treats GR as if it is above failure (we expect it to at some point) we just have not conclusively seen a failure yet.

 

[kmarinas86]

Can I also say that we are expecting GR to fail at some point because of quantum physics and a new theory is expected which incorporates both.

I'm not sure that everyone that is optimistic.

If the flyby anomaly is real, then it falsifies GR. GR would have to be modified. That would be an extraordinarily exciting discovery.

The trouble is that the flyby anomaly almost certainly isn't real. If there was a consensus among physicists that there was a significant probability that it was real, the sane thing to do would be to launch special-purpose probes to test it that would be designed so as to be immune to as many systematic errors as possible. The results would almost certainly be null, but a positive result would be super-exciting.

The tone of the above language has become very familiar to me. It's a kind of talk that makes me question the scientific enterprise itself. The above almost sounded like there was a genuine possibility that people would deliberately choose not to send a probe simply because the observation to be clarified wasn't thought to be "real" enough by some experts.

 

[Uglybb]

So this is conspiracy theory ... we "the science industry" as you call it are all in it for what ?

The money?
The glory?
Control?

 

[kmarinas86]

So this is conspiracy theory ... we "the science industry" as you call it are all in it for what ?

The money?
The glory?
Control?

No. Science is not a uniform enterprise.

I see scientists with various degrees of tolerance of change.

You know there are sometimes heated debates in science. I think this is one little area that is just being ignored.

It has nothing to do with the conspiracy theory that scientists are doing it for money, glory, or control.

However, actually, it seems that those who initiate sharp trends in scientific revolutions are more likely to seek exactly those things (especially glory). I think that actually think that helps science, rather than hindering it.

Maybe there is a lack of this desire (for glory)?

 

[PAllen]

No. Science is not a uniform enterprise.

I see scientists with various degrees of tolerance of change.

You know there are sometimes heated debates in science. I think this is one little area that is just being ignored.

It has nothing to do with the conspiracy theory that scientists are doing it for money, glory, or control.

However, actually, it seems that those who initiate sharp trends in scientific revolutions are more likely to seek exactly those things (especially glory). I think that actually think that helps science, rather than hindering it.

Maybe there is a lack of this desire (for glory)?

This quote you complain about just reflects experienced based judgment of where to invest effort on the part of one scientist. Other scientists will differ (as shown by the links). There isn't so much a broad distinction between scientists open to change and those not; instead there is a difference between scientists of where to look for the promising changes. It is good that there is such variety.

I personally would guess that the flyby effect will ultimately have a mundane explanation, as the Pioneer eventually did. Even if true, this explanation will never happen unless the effect is studied - which it has, is, and will be.

Note, I feel certain that GR will prove wrong at some point (despite the fact that it is my 'favorite' theory). The flyby anomaly just doesn't seem to me the likely place for this. The reason I am certain GR is wrong is that it has built in absurdities (singularities), built in ill definition (no real rules for the stress energy tensor), and it is a classical field theory which makes it inconsistent with the (I believe) fundamentally quantum nature of reality.

 

[TrickyDicky]

I don't think there is any conspiracy among scientists, it's just that some extremists will try at all costs to make any interesting observational finding that they can't fit in their fantasy model appear as not worthy, uninteresting, due to thermal effects or whatever comes handy.
It would be very different if somehow it could be included in the cosmological model and be called the "dark anomaly" or something like this. Then it would be anathema even to question it.
Both the Pioneer and the flyby anomalies are to this day not considered solved by any serious scientist "out there" regardless what some may say here.

 

[pervect]

Well, my POV.

The naysayers here are saying. "The house is crooked! And I never liked the color, anyway. Tear it all down, and start from scratch". The house, here, is an analogy for the theory of GR, which has been built up painstakingly over time. Not liking the color is an analogy for the apparent dislike of the theory by some for reasons that don't have much to do with how well it works.

The rest of us (and I'd put myself in this group are saying). "The house is basically structually sound, living in it is quite comfortable".

We're talking about an error of a few mm/sec here of objects moving at kilometers/second!

Certainly it's something that should be looked at, but the natural scientific process of improving our knowledge of the Earth's actual gravity field, including all the multipole-moments due to its not-quite-spherical shape is likely to resolve the issue. We can't rule out more interesting explanations at this point (for instance, a dark matter halo), but the data isn't good enough to really strongly suggest anything in particular to improve our predictions.

Meanwhile, the actual work continues, quietly, as more and more measurements are made. I'm not sure of the details of the work, but it appears we have a WGS-84 from 1984, and EGM from 84, 96, and 2008.

Conspiracy theoreists may delight in the fact that some of this ungoing work is apparently being done by the government - through the NGA - the national geospatial intelligence agency. A mysterious, spooky-sounding name, to be sure, it sounds like fertile ground for all sorts of fantastic speculations. Which I shall prudently omit on the grounds that someone would probably take me seriously.