Neutral Direction Space Time

[lovegazn]

I've often wondered but never really asked this question. What would happen if man placed a satellite in space to find a completely neutral direction by slowing down to a complete stop in space as apposed to any direction and anything else like all matter moving in every direction, what scientists would find especially while viewing live video and data from the satellite?  I'm sure there are many theories but would very much like to know if this experiment has been done before recently by any country or NASA? 

Would we then be able to tap into other dimensions? Would the satellite simply disappear or vanish if stopped in space to a zero velocity? Would we be able to find such a speed as zero? If so then would we be able to see in which direction all matter and space and time are coming from to pinpoint the center or origin of the so called big bang? 

Sorry if I'm not the best writer in the world.

I would very much like to learn more of this topic although I have spent time in a physical astronomy course, but just wondered if anyone else has their own theories, educated or not or whatever.

Thanks,

lovegazn

[Earl]

i dont think its possible as gravity propagates everywhere even to the extent of super clusters of galaxys been gravitationally bound, space it self is effected by it.

[Qualia]

I've often wondered but never really asked this question. What would happen if man placed a satellite in space to find a completely neutral direction by slowing down to a complete stop in space as apposed to any direction

I'm not sure I really understand the question, Lovegazn but my initial reaction would be to suggest that velocity is relative to reference frame. Slowing down, speeding up, coming to a halt or to a complete stop etc don't really have meaning except when referred to something else. When we say something is moving, or not, it is always relative to something.

Technically speaking, you can't say something like 'neutral direction' or 'complete stop' or without direction, because there isn't an absolute to know what can be considered neutral or how fast you're actually going, or even what is north of the North Pole . The answer will depend on your frame of reference. We may have a situation where you could say, the satellite is at rest relative to Earth. I know this because the satellite's motion is uniform and unaccelerated relative to Earth, and so we can consider it to be perfectly motionless. But someone else, someone, say, outside the solar system, would say, no way, brother, that satellite is speeding faster than a bullet, it's moving relative to the sun at some 100,000km/h.

[acey]

There is no absolute reference frame hence one cannot speak of being absolutely stationary, only stationary relative to some particular reference frame. The most general reference frame is defined by the "Hubble flow", i.e. cosmological expansion. Earth, the solar system and our galaxy are not stationary relative to that: we see this as a blue-shifting of the cosmic microwave background (CMB) in one direction, and redshifting in the opposite direction, relative to the CMB as a whole. This "dipole anisotropy" has to be factored out in maps of the CMB.

If you were stationary relative to the Hubble flow then you would see the CMB as uniform in every direction, apart from the very small variations which are a relic of quantum fluctuations at the time of inflation. You would see distant galaxies receding at a rate proportional to their distance from you. If you had been stationary with respect to the Hubble flow since the time of the Big Bang, then the time you would have recorded as having elapsed would be the time we call the age of the universe (currently reckoned to be a bit less than 14 billion years).

If, on the other hand, you were moving very fast with respect to the Hubble flow (e.g. you're a neutrino speeding through space ,and have been doing so since near the Big Bang), your "clock" would say that the universe had existed for a much shorter time. You would "see" the CMB as highly blue-shifted in the direction towards which you are travelling, and highly red-shifted in the opposite direction.

You could try and make a spacecraft stationary with respect to the Hubble flow by using rocket boosters to give it a velocity such that the CMB would show no dipole anisotropy. I think it would need to go at about 370 km/s relative to the Sun (in the appropriate direction). There's not really much point doing it, since the effect of movement relative to the Hubble flow can easily be cancelled out of any measurement, as has always been done in observations of the CMB.

Our Sun is of course moving with respect to our Galaxy, and our Galaxy is moving with respect to the Local Group of which it is a member. I believe that our Local Group of galaxies is moving at about 600km/s relative to the CMB rest frame. So our satellite would need to move at the same speed in the opposite direction, relative to the Local Group, in order to be "stationary" with respect to the CMB.

[andrew s]

There is no absolute reference frame hence one cannot speak of being absolutely stationary, only stationary relative to some particular reference frame. The most general reference frame is defined by the "Hubble flow", i.e. cosmological expansion. Earth, the solar system and our galaxy are not stationary relative to that: we see this as a blue-shifting of the cosmic microwave background (CMB) in one direction, and redshifting in the opposite direction, relative to the CMB as a whole. This "dipole anisotropy" has to be factored out in maps of the CMB.

If you were stationary relative to the Hubble flow then you would see the CMB as uniform in every direction, apart from the very small variations which are a relic of quantum fluctuations at the time of inflation. You would see distant galaxies receding at a rate proportional to their distance from you. If you had been stationary with respect to the Hubble flow since the time of the Big Bang, then the time you would have recorded as having elapsed would be the time we call the age of the universe (currently reckoned to be a bit less than 14 billion years).

If, on the other hand, you were moving very fast with respect to the Hubble flow (e.g. you're a neutrino speeding through space ,and have been doing so since near the Big Bang), your "clock" would say that the universe had existed for a much shorter time. You would "see" the CMB as highly blue-shifted in the direction towards which you are travelling, and highly red-shifted in the opposite direction.

You could try and make a spacecraft stationary with respect to the Hubble flow by using rocket boosters to give it a velocity such that the CMB would show no dipole anisotropy. I think it would need to go at about 370 km/s relative to the Sun (in the appropriate direction). There's not really much point doing it, since the effect of movement relative to the Hubble flow can easily be cancelled out of any measurement, as has always been done in observations of the CMB.

Our Sun is of course moving with respect to our Galaxy, and our Galaxy is moving with respect to the Local Group of which it is a member. I believe that our Local Group of galaxies is moving at about 600km/s relative to the CMB rest frame. So our satellite would need to move at the same speed in the opposite direction, relative to the Local Group, in order to be "stationary" with respect to the CMB.

I have often wondered why the CMB can not be considered an absolute reference frame ?

Regards Andrew

[acey]

A truly "absolute" rest frame would be one such that the laws of physics are uniquely defined with respect to that frame and would be different in other frames. For example the speed of light would be defined with respect to that frame, and would be faster or slower in frames moving relative to the absolute one. Einstein showed that no such frame exists. The CMB rest frame is the most "natural" one but it is not absolute. A neutrino that thinks the universe is five minutes old is not wrong, it's just measuring time in a different co-ordinate frame. Similarly, there is no absolute standard of height on Earth, but height above sea level is a natural choice. (That's just an analogy, not to be taken too literally).

[just_ed]

Supposedly, the big bang has no center, which would mean there is no reference point for the universe.

What about space-time? If space has no reference point, does time? The big bang occurred, but nowhere, and at no time? My head hurts.

I think humans are really limited by their ability to perceive the universe around them, and postulate as best they can. We’ve all seen a dog sitting on his haunches looking up at his master with his head cocked to one side, as if to say “huh?” That’s how I view us.
 

[ollypenrice]

I'll buy the dog anaolgy apart from the master bit. The dog, after all, is a highly intelligent creature but doesn't know everything. Neither do we. Well, scientists don't pretend to do so but others do. They are not the intelligent dogs with their heads cocked on one side, they are the stupid inbred ones biting your leg.

Olly

[Earl]

Supposedly, the big bang has no center, which would mean there is no reference point for the universe.

What about space-time? If space has no reference point, does time? The big bang occurred, but nowhere, and at no time? My head hurts.

I think humans are really limited by their ability to perceive the universe around them, and postulate as best they can. We’ve all seen a dog sitting on his haunches looking up at his master with his head cocked to one side, as if to say “huh?” That’s how I view us.

This depends on your view of the big bag, there is a growing body of thought that it was just another phase of something else.

Meaning before the big bang is not an impossibility.

http://www.dailymotion.com/video/x2345a8_bbc-horizon-what-happened-before-the-big-bang_tech

[Tiki]

I have often wondered why the CMB can not be considered an absolute reference frame ?

Regards Andrew

This might help.

How come we can tell what motion we have with respect to the CMB? Doesn't this mean there's an absolute frame of reference?

In the words of Prof.D.Scott, University of British Columbia:

'The theory of special relativity is based on the principle that there are no preferred reference frames. In other words, the whole of Einstein's theory rests on the assumption that physics works the same irrespective of what speed and direction you have. So the fact that there is a frame of reference in which there is no motion through the CMB would appear to violate special relativity!

However, the crucial assumption of Einstein's theory is not that there are no special frames, but that there are no special frames where the laws of physics are different. There clearly is a frame where the CMB is at rest, and so this is, in some sense, the rest frame of the Universe. But for doing any physics experiment, any other frame is as good as this one. So the only difference is that in the CMB rest frame you measure no velocity with respect to the CMB photons, but that does not imply any fundamental difference in the laws of physics.'