Science a GoGo's Home Page Forums General Discussion General Science Discussion Forum 3 Astronomical Unsolved Problems

The Constant acceleration of Pioneer 10
Pioneer 10-Launched in 1972, is still moving out
into deep Space. The problem is that nobody knows why it has speeded up.
Scientists have ruled out a fuel leak, software error, or solar wind. Its minute, but constant acceleration, has been causing Cosmologists problems as to what might be causing it.

Microwave background temperature appears the same everywhere?
Temperature measurements on our Universe appear to be uniform. But the two edges of our Universe are measured to be at least 28 billion light years apart. But since our universe is only 14 billion years old, how could heat radiation have evened out the hot and cold spots created in the big bang?. Leaving the thermal equilibrium as seen today, when the speed of light is supposed to be constant?

Could there be a Planet X?
Reasoning is as follows.
Travelling out beyond Pluto, you reach the Kuiper Belt. A region full of rocks and ice. Once you have passed thru the Kuiper Belt there is nothing. The only explanation seems to be that a large Planet has swept the area clean. If Planet X is there, it can only be detected visually,... but not so far.

1) Tiny Angels

2) Inverse-Kinematics

3) Giant Alien Vacuum Cleaner (GAV-C)

I am in full agreement with (1) & (3) though I believe (2) is exactly wrong... It is Kinematics (classic) that drives the observed expansion of the nothing. The more nothing, the greater the expansion rate,,, which may relate to (1) & (3) as well ~regards

Mike:

I think Planet X is out as is Nemesis (the sun
s theoretical dark binary companion). Either would be moving in its orbit such that the change in direction would be discernable.

My supposition is that it is a direct consequence of the distribution of dark matter (or) a property of space, so far undiscovered, that relates to its flatness as the spacecraft moves away from the warping caused by the gravitational fields caused by the planets.

Time will tell. But I doubt either of us will be around to hear the announcement.

join the cryogenics club!

Hi Mike:

I have found that question to be intriguing as well.

For what it is worth my thought has been not that there are bodies out there attracting things, although that is a viable offer, but rather that as objects get farther from the Sun?s gravitational envelope they experience less restraint. If all things start out with potential acceleration greater than demonstrated at the start then as they are relieved of the Sun?s restraints they will pick up speed, due in part to the rotation of the Sun?s gravitational envelope. This is a kind of sling shot effect providing the push. Maybe not.
jjw

You are right, outside of the Kuiper Belt, many 'outward' moving objects would be lost in space. With the converse true, regarding items collected within the Kuiper Belt?.
There is a 'Pluto-Kuiper' mission proposed by NASA to reach that area, around 2015, and explore for a further 10 years. (I find those figures optimistic), but we can only wait and see.
If there is an X Planet scavenging out there, it could take 400 years plus, to make 1 revolution around the Sun. The Sun might be between it, and us, for dozens of years, and/or, be too far away for us to detect any pull upon Pluto. Too small, with a low albeido, would make it virtually impossible to detect from Earth.

Mike:

I do not expect agreement or acceptance from any one so I just stumble ahead as I see things. Assuming that I have calculated that the minimum radius of the Solar System is about 32 billion miles we can place your mystery planet in an orbital radius of about 25 billion miles and still be well within reasonable expectation of there being a large object; say a planet. At that distance it will have an orbital velocity of about 1.128 miles per second. The full hypothetical orbit will be 157,080,000,000 miles which at 1.128 miles a second which will take it about 4,412.73 years to make one orbit around the Sun and present a face that is so dim as to defy discovery. I agree with you and others that suspect our beginnings included a potential binary companion which would require an object of considerable mass, close to that of the Sun. I don?t look for it.

Some geologists have speculated on world upheavals about every 3600 years or so and we need only alter the orbit a little to put our hypothetical massive object right on time.
jjw

The probe that isn't where we thought it would be:

SR was used, and the theory of time dilation, causing the difference between prediction and observation.

The Pioneer anomaly will be testedmwith another data point. New Horizons mission to Pluto will travel at ~47,000 mph (13 miles/second) after its gravitational sling at Jupiter. It is rich with power from its plutonium-238 RTGs. Pioneer is moving at 27,228 mph and is 8.24 billion miles distant,

http://spaceprojects.arc.nasa.gov/Space_Projects/pioneer/PNStat.html

In less than 20 years we will know if the Pioneer anomaly is idiosyncratic or real.

And my prediction ... here and now ... is that it is real.

Look me up in 20 years.

Question by Mike Kremer:

Microwave background temperature appears the same everywhere?
Temperature measurements on our Universe appear to be uniform. But the two edges of our Universe are measured to be at least 28 billion light years apart. But since our universe is only 14 billion years old, how could heat radiation have evened out the hot and cold spots created in the big bang?. Leaving the thermal equilibrium as seen today, when the speed of light is supposed to be constant?

I am going to speculate wildly now; just for the fun.
The microwave background radiation is the same as the blackbody cavity radiation of the universe. In order to model blackbody radiation one can assume either localised photons subject to Bose-Einstein statistics or standing waves stretching ove the whole cavity. It indicates that one can decompose the superposed wave representing micro-wave radiation in two equivalent ways. As standing waves, the radiation is "aware" of the whole universe and therefopre the temperature is nearly uniform. When measuring the radiation these standing waves "instantaneously" collapse to form localised entities. The entanglement and disentanglement of two photons can be explained in a similar manner.

Ah, the old "horizon" problem. This becomes a "non-mystery" if you accept the theory of inflation.
Basically, in the micro billionths of a second after the Big Bang the whole universe was so small that everywhere was in causal contact with everywhere else and the uniform temperature of the universe was already secured. Then inflation kicked in and the entire universe was inflated by an unbelievably huge amount in an unbelievably short amount of time. (The universe expanded at a speed way over the speed of light but this does not contravene SR, only super light speed within the universe itself does that.)
When the extremely brief period of expansion came to a halt, the universe was huge, but already at the same temperature everywhere, as it is today.
Inflation theory also explains why we perceive (and currently measure) the visible universe to be flat. Any initial curvature the universe had would have been totally "ironed out" by this massive inflation, at least on a local scale, which is as far as we can see.

This is how I understand the nuts and bolts of inflation theory, please correct me if I am wrong.

Here's a bit I stole from New Scientist
A modified theory of gravity that incorporates quantum effects can explain a trio of puzzling astronomical observations ? including the wayward motion of the Pioneer spacecraft.
The theory, called scalar-tensor-vector gravity (STVG), adds quantum effects to Einstein's theory of general relativity. As in other branches of physics, the theory says that quantum fluctuations can affect the force felt between interacting objects.

In this case, a hypothetical particle called a graviton ? which mediates gravity ? appears in large numbers out of the vacuum of space in regions crowded with massive objects such as stars. "It's as if gravity is stronger" near the centres of galaxies, Brownstein told New Scientist. "Then, at a certain distance, the stars become sparse, and the gravitons don't contribute that much." So at larger distances, gravity returns to the behaviour described by Newton.

Pioneer 10 anomaly
Brownstein and Moffat tested the theory in several ways. They estimated that their gravitational change occurs 46,000 light years out from the centre of a large galaxy and half that distance for a small galaxy. They applied these estimates to 101 observed galaxies, and found that both their theory and MOND could account for their rotations. "The point is that neither of the two theories had any dark matter in them," says Brownstein.

But the theories did diverge when the pair tested them against observations of 106 galaxy clusters. MOND could not reproduce the observed cluster masses but STVG accounted for more than half.

Furthermore, the team tested the theory against observations of NASA's 34-year-old Pioneer 10 spacecraft, which appears about 400,000 kilometres away from its expected location in the outer solar system. Brownstein says the theory fits observations of the so-called Pioneer anomaly (see New Scientist feature, 13 things that do not make sense), while MOND cannot address it because Pioneer's acceleration is above a0.

We may laugh at the idea that people once believed that the sun revolved around the earth. At the time however, it was a very practical idea that seemed confirmed by their observation after all: the sun rises in the east, sets in the west.. etc. The conclusion was wrong but not all of the science behind it was. Is it possible that science as we see it nowadays has just as much errors in it? It doesn't mean we're wrong about everything in science but maybe some of the "constants" we believe are constant don't work that way on a larger scale???