Celestial ephemerides in an expanding universe

this is interesting,

"Previous research has focused on mechanical explanations for the Pioneer anomaly, such as the recoil of heat from the craft's electrical generators pushing the craft backwards," Kopeikin said. "However that only explains 15 to 20 percent of the observed deceleration, whereas it is the equation for photons that explains the remaining 80-85 percent." Physicists must be careful when dealing with propagation of light in the presence of the expansion of space, noted Kopeikin, since it is affected by forces that are irrelevant in other equations. For example, the expansion of the universe affects photons, but doesn't influence the motion of planets and electrons in atoms.

Read more at: phys.org...

phys.org...

the pioneer anomaly is basically where the spacecraft was observed to slow down, but no known reason existed that could account for the deceleration.

"The Pioneer spacecraft, two probes launched into space in the early 70s, seemed to violate the Newtonian law of gravity by decelerating anomalously as they traveled, but there was nothing in physics to explain why this happened," said Sergei Kopeikin, professor of physics and astronomy in MU's College of Arts and Science. "My study suggests that this so-called Pioneer anomaly was not anything strange. The confusion can be explained by the effect of the expansion of the universe on the movement of photons that make up light and radio waves."

Read more at: phys.org...

so if the expansion of the universe can "alter" the perceived time/distance in a "round trip" of a photon then the anomaly can be explained by the expansion of local space effecting the photon over distance as signal travels from point to point, then back again.

an "optical illusion" that effects perceived distance,
it becomes very important to future space travel to know how far things are, before you plan to travel there.

"Discerning the effect of the expansion of the universe on light is important to the fundamental understanding of space and time. The present study is part of a larger on-going research project that may influence the future of physics."

Read more at: phys.org...

phys.org...

this can effect problems in space/time and observation over distance,
has very interesting implications




xploder

the pioneer anomaly is basically where the spacecraft was observed to slow down, but no known reason existed that could account for the deceleration.

I guess Sergei Kopeikin had not heard about the work of Slava Turyshev et al, when he published his paper in July.

After an extensive examination of data from the spacecraft the source of the anomalous acceleration was determined. No change in the speed of light required, thermal recoil accounts for the full effect.

As a novel element of our investigation, we develop a parameterized model for the thermal recoil force and estimate the coefficients of this model independently from navigational Doppler data. We find no statistically significant difference between the two estimates and conclude that once the thermal recoil force is properly accounted for, no anomalous acceleration remains.

arxiv.org...

reply to post by Phage

We investigate the possibility that the anomalous acceleration of the Pioneer 10 and 11 spacecraft is due to the recoil force associated with an anisotropic emission of thermal radiation off the
vehicles.

arxiv.org...

so thats the recoil forces theory, i remember reading that a short while ago,


at what point does the recoil theory address expansion of the universe?

xploder

reply to post by XPLodER

I guess you missed the point.

The Pioneer anomaly has been solved and it has nothing to do with the expansion of the Universe. It is not caused by any change in the movement of photons. Kopeikin used his idea to try to explain something that had already been explained.

reply to post by Phage


at what point does the expansion happen locally inside our helio sphere?



and what effects would that have on round trip times and the nature of the signal wave/photon?

does locally expanding "space" have an effect on the measured "deceleration?

xploder

reply to post by Phage


so this is just a thought experiment?
is it widely considered "solved"?

i find the new idea...... compelling,



xploder

Be cool if it just stopped that would bend some heads...

reply to post by XPLodER

at what point does the expansion happen locally inside our helio sphere?

There is no "point". Expansion occurs everywhere but at such a small scale inside the Solar system that it cannot be measured.

and what effects would that have on round trip times and the nature of the signal wave/photon?

Nothing measurable.

does locally expanding "space" have an effect on the measured "deceleration?

No. Thermal effects do.

Originally posted by abeverage
Be cool if it just stopped that would bend some heads...

you are talking about the literal meltdown of thousands of scientists minds,
arguments that go on for years lol

it would be interesting and scary at the same time

xploder

reply to post by XPLodER

i find the new idea...... compelling,

Yes, of course you do.
It gives you yet another way to declare that the Universe is not the size it is. However, the idea has not be demonstrated to be valid.

reply to post by Phage


i had not realised the anomaly had been so conclusively solved,

have you read the paper?

Originally posted by Phage
reply to post by XPLodER

 

i find the new idea...... compelling,

Yes, of course you do.
It gives you yet another way to declare that the Universe is not the size it is. However, the idea has not be demonstrated to be valid.

i have been quite open about my thoughts and biasis on the matter,
and you are correct in my reasons for starting the thread,

it is not that i wish to "declare" the universe is a different size that perceived, but to discuss and debate the papers that sort of point in that direction. (optical implications)

you know very well my thought on optics and gravitational lensing,
i prefer to discuss than proclaim, although i have been guilty of that in the past




xploder

reply to post by Phage


so your reason to refute the paper out of hand is that expansion of the universe in the local solar system is to small to effect the measurements, but the thermal models dont take this into account at all,

and the second is,
that someone else has already explained it to a satisfactory level?

xploder

reply to post by XPLodER

so your reason to refute the paper out of hand is that expansion of the universe in the local solar system is to small to effect the measurements, but the thermal models dont take this into account at all,

The claim that the Pioneer anomaly is caused by the effects of the expansion of the Universe on the speed of light is refuted. The thermal models demonstrate what was happening on the spacecraft. The heating was the prior unknown source of acceleration. There is nothing to take into account other than the heating. It fully accounts for the acceleration. If the expansion were involved the anomaly would be greater that it is.

that someone else has already explained it to a satisfactory level?

Yes.

reply to post by Phage


thank you for your patience explaining it to me

but what does this mean then?

"Previous research has focused on mechanical explanations for the Pioneer anomaly, such as the recoil of heat from the craft's electrical generators pushing the craft backwards," Kopeikin said. "However that only explains 15 to 20 percent of the observed deceleration, whereas it is the equation for photons that explains the remaining 80-85 percent."

Read more at: phys.org...

phys.org...

if i am reading this correctly the paper says there was some uncertainty as to weather or not the radiation model could "account" for all the deceleration observed.

on physorg,
they say it can only account for 20% of the observed slow down

xploder

reply to post by XPLodER

but what does this mean then?

It means that Kopeikin was not familiar with more recent studies of the anomaly.

Originally posted by XPLodER

Originally posted by abeverage
Be cool if it just stopped that would bend some heads...

you are talking about the literal meltdown of thousands of scientists minds,
arguments that go on for years lol

it would be interesting and scary at the same time

xploder

True but sadly this will never happen cause our Universe has to have rules...