CMBR Dipole: Speeding through the Universe? (2009 Sept 6)

[gaz2inf]

The Taoists had it right. Yin & Yang!

http://apod.nasa.gov/apod/ap090906.html

[Storm_norm]

so umm, are there guesses in the astronomical and astrophysical community as to the answers to the last questions? why are we moving so fast?

[Boner]

If we are moving so fast, which I don't doubt by the way, why do other changes 'out there' take so long to reach us? I'm assuming it is because of the massive light distances between objects. But still, 600 km per second. 1,8921,600,000km per year. That must be pretty close to the speed of light? Are we moving in an orbit, which would explain why we never catch up to, or move closer to things? I've seen those pictures of galaxies that are merging, surely at that speed things must happen fairly quickly?

[gwrede]

The picture shows some "dots" along the middle. I'm sure they don't come from the CMBR, but are artifacts of some kind.

I'd love to see a proper explanation for them.

If you look really carefully, you can find up to eight such dots, horizontally aligned halfway up the picture.

[gwrede]

If we are moving so fast, which I don't doubt by the way, why do other changes 'out there' take so long to reach us? I'm assuming it is because of the massive light distances between objects. But still, 600 km per second. 1,8921,600,000km per year. That must be pretty close to the speed of light? Are we moving in an orbit, which would explain why we never catch up to, or move closer to things? I've seen those pictures of galaxies that are merging, surely at that speed things must happen fairly quickly?

You could think of it as time itself being different for objects of a different size.

If you want to see how clouds move in the sky, you need to take a time lapse video (that is, speed things up), to see how clouds form, move and transform in the sky. Similarly, for small things, you would want a slow motion video. For example, a busy ant colony looks a mess unless you watch the ants in slow motion.

600 km per second is 1/500 the speed of light. At that speed, it takes us 500 years to move the distance of one light year. Yes, that is pretty fast.

[neufer]

The picture shows some "dots" along the middle. I'm sure they don't come from the CMBR, but are artifacts of some kind.

I'd love to see a proper explanation for them.

If you look really carefully, you can find up to eight such dots, horizontally aligned halfway up the picture.

The biggest obstacle to seeing anything extragalactic at any wavelength is to first see through the Milky Way.

• http://antwrp.gsfc.nasa.gov/apod/ap030217.html
  http://antwrp.gsfc.nasa.gov/apod/ap011020.html
  http://antwrp.gsfc.nasa.gov/apod/ap090321.html

You are seeing artifacts of the Milky Way, especially the galactic center in the middle and our own Orion-Cygnus spiral arm on the left & right.

[neufer]

so umm, are there guesses in the astronomical and astrophysical community as to the answers to the last questions?

why are we moving so fast?

"We are not special" (...present company excluded, of course).

<<Codified by the teachings of Aristotle and Ptolemy, and by the preachings of the Roman Catholic Church, people generally accepted Earth as the center of all motion. It was self-evident: the universe not only looked that way, but God surely made it so... Many generations of thinkers, both religious and scientific, have been led astray by anthropic assumptions. In the absence of dogma and data, history tells us that it's prudent to be guided by the notion that we are not special, which is generally known as the Copernican principle.>>

[twixter]

My question might be more appropriate in a forum for quantum physics, but it does pertain to today's APOD in a roundabout way. So, it seems we are moving through the cosmic microwave background radiation at about 600 Kps. I am reminded of a nagging question I have always had about string theory, which claims there is this overall structure to space itself, on a scale many orders of magnitude smaller than the smallest known subatomic particle, which is 11 or 12-dimensional, with most of the dimensions "curled up". I have always wondered, if this "structure of space-time" exists, then are we moving through it? Does it even make sense to ask if we are moving through it? Is it like asking if a dog has a Buddha nature? Is it equally valid to say that we move through it at any chosen sublight velocity? This is like the background "ether" which most physicists reject these days. Everything is relative, right? But if that were true, then this structure of space would have to be the same everywhere in the Universe, with no variation, right? Is that what the string theory model implies? Or can we now say, based on the CMBR measurements, that we are moving through the structure at 600 Kps?

[orin stepanek]

My Question is this: Would the CMBR be viewed the same whether we were on the leading or trailing edge of our orbit around the Milky Way galaxy? Or is the orbital speed around the galaxy too minuscule to be relevant?

Orin

[bystander]

The Taoists had it right. Yin & Yang!

This garden universe vibrates complete
Some, we get a sound so sweet
Vibrations reach on up to become light
And then through gamma, out of sight

Between the eyes and ears there lie
The sounds of colour and the light of a sigh
And to hear the sun, what a thing to believe
But it's all around if we could but perceive

To know ultraviolet, infrared and X-rays
Beauty to find in so many ways
Two notes of the chord, that's our full scope
But to reach the chord is our life's hope

And to name the chord is important to some
So they give it a word, and The Word is...

OM

Thinking is the best way to Travel!

[neufer]

My Question is this: Would the CMBR be viewed the same whether we were on the leading or trailing edge of our orbit around the Milky Way galaxy? Or is the orbital speed around the galaxy too minuscule to be relevant?

<<Recent measurements by the Very Long Baseline Array (VLBA) have revealed that the Milky Way is much heavier than some previously thought. The mass of our home galaxy is now considered to be roughly similar to that of our largest local neighbour, the Andromeda Galaxy. By using the VLBA to measure the apparent shift of far-flung star-forming regions when the Earth is on opposite sides of the Sun, the researchers were able to measure the distance to those regions using fewer assumptions than prior efforts. The newer and more accurate estimate of the galaxy's rotational speed (and in turn the amount of dark matter contained by the galaxy) puts the figure at about 254 km/s, significantly higher than the widely accepted value of 220 km/s. This in turn implies that the Milky Way has a total mass equivalent to around 3 trillion Suns, about 50% more massive than some previously thought.>>

<<From the CMB data it is seen that our local group of galaxies (the galactic cluster that includes the Solar System's Milky Way Galaxy) appears to be moving at 627 ± 22 km/s relative to the reference frame of the CMB (also called the CMB rest frame) in the direction of galactic longitude l = 276 ± 3°, b = 30 ± 3°. This motion results in an anisotropy of the data (CMB appearing slightly warmer in the direction of movement than in the opposite direction). The standard interpretation of this temperature variation is a simple velocity redshift and blueshift due to motion relative to the CMB.>>

[gaz2inf]

There is no proof that the local physical laws are the same everywhere in the universe, just as there is no proof that they are not. How could we know when we've never ventured beyond our own backyard? As a theoretical consideration perhaps space/time causes not our local perception of time, but some galactic metric of time to change indicating a greater red shift than an outside observer would perceive. If the calculations show we are moving near the speed of light does that not imply an altered time meter for our local space? Perhaps the universe isn't expanding at an ever increasing pace, but that our galactic neighborhood is zipping through time faster and faster. Perhaps this is affected by our ever shifting position in our galaxy and/or our galaxy's ever shifting position in the local galactic group and/or our local galactic group's ever shifting position, etc. . .

[neufer]

There is no proof that the local physical laws are the same everywhere in the universe, just as there is no proof that they are not. How could we know when we've never ventured beyond our own backyard? As a theoretical consideration perhaps space/time causes not our local perception of time, but some galactic metric of time to change indicating a greater red shift than an outside observer would perceive. If the calculations show we are moving near the speed of light does that not imply an altered time meter for our local space? Perhaps the universe isn't expanding at an ever increasing pace, but that our galactic neighborhood is zipping through time faster and faster. Perhaps this is affected by our ever shifting position in our galaxy and/or our galaxy's ever shifting position in the local galactic group and/or our local galactic group's ever shifting position, etc. . .

Now We're All Running on Leno Time
By By Hank Stuever, Washington Post Staff Writer
Friday, September 4, 2009; 12:11 PM

To judge from the hype, Leno's presence on your television before the local news will rip open some fabric in the time-space-TV continuum -- as if that fabric still existed. And moving him is not like time travel, but in the television world, it might as well be. Jay is changing, ergo prime time is changing, ergo our world is changing!

[DeepField]

When I first started reading Asimov and other science authors, a while ago, they said that one of the reasons Newton was worng was because he proposed an "absolute space" relative to which everything moved (or not). Einstein came up with his theories that said that there was no such thing, and that every observer had an equally valid mark of reference against which everything moved (or not).

Recently, however, it seems to me, with experiments such as this one, that there is indeed an absolute space. Am I missing something?

[bystander]

When I first started reading Asimov and other science authors, a while ago, they said that one of the reasons Newton was worng was because he proposed an "absolute space" relative to which everything moved (or not). Einstein came up with his theories that said that there was no such thing, and that every observer had an equally valid mark of reference against which everything moved (or not).

Recently, however, it seems to me, with experiments such as this one, that there is indeed an absolute space. Am I missing something?

Any observer would have a similar view of the universe relative to the observer.

The traditional formulation of the Copernican mediocrity principle is usually played out in the following way: Ancients of the Middle East and west once thought that the Earth was at the center of the universe, but Copernicus proposed that the Sun was at the center. In the 1930s, RJ Trumpler found that the solar system was not at the center of the Milky Way Galaxy (as Jacobus Kapteyn claimed), but 56% of the way out to the rim of the galaxy's core. In the mid-twentieth century, George Gamow (et al.) showed that although it appears that our Galaxy is at the center of an expanding universe (in accordance with Hubble's law), every point in space experiences the same phenomenon. And, at the end of the twentieth century, Geoff Marcy and colleagues discovered that extrasolar planets are quite common, putting to rest the idea that the Sun is unusual in having planets. In short, Copernican mediocrity is a series of astronomical findings that the Earth is a relatively ordinary planet orbiting a relatively ordinary star in a relatively ordinary galaxy which is one of countless others in a giant universe, possibly within an infinite multiverse.

However:

The standard conclusion that the observed isotropy of the cosmic microwave background radiation (CMB), combined with the Copernican principle, requires a homogeneous universe (i.e., the cosmological principle), is called into question by some recent findings.

In 2008, researchers studying fluctuations in the cosmic microwave background caused by the scattering of its microwave photons by hot X-ray-emitting gas inside clusters of galaxies found that the 700 clusters reaching out up to 6 billion light-years are all moving nearly 3.2 million km/h toward a 20-degree region in the sky between the constellations of Centaurus and Vela. This flow is difficult to explain by gravitation and may be indicative of a tilt exerted across the visible universe by far-away pre-inflationary inhomogeneities.

[neufer]

When I first started reading Asimov and other science authors, a while ago, they said that one of the reasons Newton was worng was because he proposed an "absolute space" relative to which everything moved (or not). Einstein came up with his theories that said that there was no such thing, and that every observer had an equally valid mark of reference against which everything moved (or not).

Recently, however, it seems to me, with experiments such as this one, that there is indeed an absolute space. Am I missing something?

If there was an "absolute space" then:

• One could perform an experiment WITHIN the confines of an enclosed space ship
  (e.g., a Michelson-Morley experiment) to determine
  how fast and/or in what direction the ship was moving.

One is NOT permitted to look out a window at ANYTHING (include the CBR).

(This does not mean that some sort of Mach's principle doesn't apply, however.)

[DeepField]

If there was an "absolute space" then:

• One could perform an experiment WITHIN the confines of an enclosed space ship
  (e.g., a Michelson-Morley experiment) to determine
  how fast and/or in what direction the ship was moving.

One is NOT permitted to look out a window at ANYTHING (include the CBR).

The Michelson-Morley experiment was, I understand, trying to determine whether there was a luminiferous ether, which was related but was not the same as absolute space. What I understand for absolute space is a special frame of reference against which anything can be said to be at rest or at motion, and that condition seems to be filled by the cosmic background.

"Newton therefore held that physics required the conception of absolute space, a distinguished frame of reference relative to which bodies could be said to be truly moving or truly at rest."

[Chris Peterson]

What I understand for absolute space is a special frame of reference against which anything can be said to be at rest or at motion, and that condition seems to be filled by the cosmic background.

No, because there is no universal cosmic background. Every observer in the Universe sees a different cosmic background. How could something like that be an absolute frame of reference? - it isn't even a "thing" in any reasonable sense of the word.

Certainly, it might be useful to us, from our viewpoint, to treat it as a sort of highest level frame of reference (although once we are able to detect weak gravity waves, we'll be able to see somewhat beyond the CMB). But that's just a measurement convenience, it doesn't make that frame fundamentally special in any way.

[NoelC]

No, because there is no universal cosmic background

Doesn't that fly in the face of the very definition of "background"?

The way I understand it, the universe has been cooling since the big bang, and (if you follow the big bang theory) it all came into being at once, and has thus been cooling for about the same amount of time.

Now, if pretty much the whole of the universe off one way appears warmer than the whole of it off the other way, does this mean:

1. We're moving?
2. The universe is simply warmer off one way than the other?
3. The laws of physics are different off one way than the other (e.g., because the concentration of mass is more or less)?

Generally speaking, I believe in #1, possibly because there's some comfort in thinking there's something "fixed" or "absolute" that we can measure about the universe, and that having observed that it feels that we're somewhat oriented. Now if they would just determine which way is up, I'll get over this vertigo.

One thing's for sure: It's simply fascinating to think about this.

-Noel

[neufer]

No, because there is no universal cosmic background

Doesn't that fly in the face of the very definition of "background"?

• -------------------------------------------------------------
  BACKGROUND, n. [1828 Webster edition]
  1. Ground in the rear or behind, as opposed to the front.
  2. A place of obscurity, or shade; a situation little seen, or noticed.
  -------------------------------------------------------------

The way I understand it, the universe has been cooling since the big bang, and (if you follow the big bang theory) it all came into being at once, and has thus been cooling for about the same amount of time.

We observe the Cosmic Background as a 13.7 billion year old spherical shell of hot plasma that is under a tremendous red shift.

Someone living in a galaxy that evolved out of that spherical shell of plasma observes their own Cosmic Background as a different 13.7 billion year old spherical shell of hot plasma... one out of which we ourselves have evolved.

Now, if pretty much the whole of the universe off one way appears warmer than the whole of it off the other way, does this mean:

1. We're moving?
2. The universe is simply warmer off one way than the other?
3. The laws of physics are different off one way than the other (e.g., because the concentration of mass is more or less)?

Generally speaking, I believe in #1, possibly because there's some comfort in thinking there's something "fixed" or "absolute" that we can measure about the universe, and that having observed that it feels that we're somewhat oriented. Now if they would just determine which way is up, I'll get over this vertigo.

Captain Cook sailing on the HMS Endeavour in the middle of the Pacific on a cloudy day can measure his motion

1) vis-a-vis the water or
2) vis-a-vis the clouds

but knowing neither the ocean currents nor the winds
Cook would be hard pressed to know what his actual motion was.

One thing's for sure: It's simply fascinating to think about this.

For sure.

[Chris Peterson]

No, because there is no universal cosmic background

Doesn't that fly in the face of the very definition of "background"?

How so? Consider two people walking around in the fog. Each person has a local background, which is a few meters away. Each could make their own measurements, and might or might not seem to record the same thing, because their individual backgrounds are coming from different places. It's the same with the CMB. This background is nothing more than the highly redshifted photons that were present when the Universe became transparent to EM. When you change your location, you are observing different photons emitted from a different place. An observer sees photons that lie along a causal path unique to his location.

To put it differently, the CMB is not a spherical shell with components (like galaxies) situated somewhere within it. The CMB is a spherical shell that is equidistant from every point in the Universe. When you change position, you don't somehow get closer to one "wall" of the background.

Now, if pretty much the whole of the universe off one way appears warmer than the whole of it off the other way, does this mean:

1. We're moving?
2. The universe is simply warmer off one way than the other?
3. The laws of physics are different off one way than the other (e.g., because the concentration of mass is more or less)?

We are only seeing the observable Universe. Almost certainly, a vastly larger (perhaps infinite) part of the Universe is not accessible to us because it lies outside our region of causality. So what we are seeing is only the background of our local part of the Universe, and the fact that this asymmetry exists most likely means we are moving within this zone. That is no surprise- pretty much everything is moving. The real question here is why we appear to be moving three or four times faster than would be expected. It is intriguing to consider possibility two, that the local background is truly not uniform, because it leads to interesting implications about the Big Bang itself. But I think most scientists consider that possibility fairly slight. Option three is probably only taken seriously by a fringe element, if that.

[astrolabe]

Hello All,

I'm curious.The Milky Way, along with a ton of other Galaxies, is moving about 1.4 million mph toward the Shapley Supercluster (which is estimated to have the mass of around 10,000 Milky Ways) via the so-called Great Attractor which is in front of it.

1.) For the sake of orientation, is the Andromeda Galaxy (M31) going before us and we are catching up or is it behind us and it's catching up.

2.) Because of our motion with respect to the CMBR do Galaxies in the red-shifted half appear to have a different rate of accelerated expansion per given distance than the ones in the blue-shifted half, just generally speaking of course.

3.) And lastly, one could surmise the point that if a Galaxy does not display a shift (either toward the red or blue) then it's pace is more in keeping or similar with our own Milky Way? Or is it possibly on a different angular vector- seemingly more perpendicular or acute in nature?

[Chris Peterson]

1.) For the sake of orientation, is the Andromeda Galaxy (M31) going before us and we are catching up or is it behind us and it's catching up.

If I understand the galactic coordinates as plotted (why don't they overlay a grid?), then M31 is in the lower left quadrant, meaning that in your terminology, you could say it's in front of us.

2.) Because of our motion with respect to the CMBR do Galaxies in the red-shifted half appear to have a different rate of accelerated expansion per given distance than the ones in the blue-shifted half, just generally speaking of course.

No way to know. In part, it depends on the interpretation of the data. It's possible that it shows an asymmetry in the expansion rate of space, but it's more likely that we're just seeing a Doppler shift (which is different than what causes cosmological redshifts) because we are moving relative to the background. That latter is the more widely accepted view, and if true, means the expansion of space is uniform and it doesn't matter in what direction we look at some particular galaxy. Of course, this effect is small compared with ordinary cosmological redshift, and there's no way to separate cosmological redshift from Doppler redshift. When we measure any galaxy's redshift, we are going to see both, but since we don't know the galaxy's distance with extreme accuracy, nor our relative velocities, we can only assume that most of the shift is cosmological.

3.) And lastly, one could surmise the point that if a Galaxy does not display a shift (either toward the red or blue) then it's pace is more in keeping or similar with our own Milky Way? Or is it possibly on a different angular vector- seemingly more perpendicular or acute in nature?

If we see no redshift, it means that the combination of the expansion of space and the relative motion of the two galaxies results in no redshift (not very profound). We don't see that with any distant galaxies, but we might with nearby galaxies, where redshift from the expansion of space could be zero, or at least small compared with Doppler redshift. And yes, the redshift is only useful for the vector component that is in our direction. It doesn't tell anything about the motion component perpendicular to our direction of view.

[neufer]

1.) For the sake of orientation, is the Andromeda Galaxy (M31) going before us and we are catching up or is it behind us and it's catching up.

If I understand the galactic coordinates as plotted (why don't they overlay a grid?), then M31 is in the lower left quadrant, meaning that in your terminology, you could say it's in front of us.

The map is NOT a map of : Red = Redshift /// Blue = Blueshift
rather it is a map of : Red = Hotter = Blueshift /// Blue = Colder = Redshift
(This is why the Milky Way shows up in Red everywhere.)

Hence M31 is trailing us towards the Shapley Supercluster.

http://upload.wikimedia.org/wikipedia/c ... W_Nasa.jpg
-------------------------------------------------

<<The Shapley Supercluster (Shapley Concentration) is the largest concentration of galaxies in our nearby Universe that forms a gravitationally interacting unit, thereby pulling itself together instead of expanding with the Universe. It appears as a striking overdensity in the distribution of galaxies in the constellation of Centaurus, approximately 650 million light years from the Milky Way.

The Shapley Supercluster lies very close to the direction in which the Local Group of galaxies (including our Galaxy) is moving with respect to the CMB frame. This has led many to speculate that the Shapley Supercluster may indeed be one of the major causes of our peculiar motion (the Great Attractor), and has led to a surge of interest in this Supercluster.>>

Note: Shapley's z = .048 puts it well in front of the CMBR but far
enough away to be pulling away from us at almost 14,000 km/s

If our meager 650 km/s motion in the direction of Shapley is mostly
gravitational then it must have been the result of Shapley's gravitational
attraction way back when the universe was only a billion or so years old.

[NoelC]

It's great when you clarify things like that Art. Never stop!

-Noel