by neufer » Sun Aug 08, 2021 8:19 pm
Chris Peterson wrote: ↑Sun Aug 08, 2021 1:06 pm
neufer wrote: ↑Sun Aug 08, 2021 2:11 am
Chris Peterson wrote: ↑Sat Aug 07, 2021 8:30 pm
I'd say that every point in the Universe has very nearly the same amount of mass surrounding it... both in the observable universe and the Universe as a whole. That is, just as every point can be treated as the geometric center of the 3D universe, so to can it be treated as very close to the center of mass of the Universe. The ability to answer the question lies in our ability to know the topology of the Universe, which appears to be discoverable.
The center of mass of the Universe is at "the Big Bang singularity" in which
space & time lose all meaning because they are just coming into existence.
The "singularity" you speak of is not a singularity
dimensionally at all. It is a physical point in the Universe, defined by (0,0,0,0). It is not, however, accessible to us. Which is why I specifically referred to the center of mass of the
3D universe, where (assuming a topologically closed universe... a point that remains unsettled) it is reasonable to treat every 3D point as the center of mass.
Due to light speed time delays of gravitational forces:
that (0,0,0,0) physical point in the Universe (along with all the mass & energy between it & us) is the only Universe accessible to us. We observe either gravitational decelerations & accelerations with respect to that very (0,0,0,0) physical point (and not any other distant "center of mass").
Note, however, there has also been a natural physical attraction to Shapley Supercluster
local mass concentration:
https://en.wikipedia.org/wiki/Cosmic_microwave_background#CMBR_dipole_anisotropy_(%E2%84%93_=_1) wrote:
<<The cosmic microwave background (CMB) dipole moment could also be interpreted as the peculiar motion of the Earth toward the CMB. From the CMB data, it is seen that the Sun appears to be moving at 368 ± 2 km/s relative to the reference frame of the CMB (also called the CMB rest frame, or the frame of reference in which there is no motion through the CMB). The Local Group — the galaxy group that includes our own Milky Way galaxy — appears to be moving at 627 ± 22 km/s 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 red shift and blue shift due to motion relative to the CMB.>>
https://en.wikipedia.org/wiki/Great_Attractor wrote:
<<The Great Attractor is a gravitational anomaly in intergalactic space and the apparent central gravitational point of the Laniakea Supercluster. The observed anomalies suggest a localized concentration of mass millions of times more massive than the Milky Way. However, it is inconveniently obscured by our own Milky Way's galactic plane, lying behind the Zone of Avoidance (ZOA), so that, in visible light wavelengths, the Great Attractor is difficult to observe directly.
The anomaly is observable by its effect on the motion of galaxies and their associated clusters over a region of hundreds of millions of light-years across the universe. These galaxies are observable above and below the ZOA; all are redshifted in accordance with the Hubble Flow, indicating that they are receding relative to us and to each other, but the variations in their redshifts are large enough and regular enough to reveal that they are slightly drawn towards the anomaly. The variations in their redshifts are known as peculiar velocities, and cover a range from about +700 km/s to −700 km/s, depending on the angular deviation from the direction to the Great Attractor.
The Great Attractor itself is moving towards the Shapley Supercluster.>>
https://en.wikipedia.org/wiki/Shapley_Supercluster wrote:
<<
The Shapley Supercluster or Shapley Concentration (SCl 124) 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. It is 650 million light-years away (z=0.046).
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 cosmic microwave background (CMB) frame of reference. This has led many to speculate that the Shapley Supercluster may indeed be one of the major causes of our galaxy's peculiar motion—the Great Attractor may be another—and has led to a surge of interest in this supercluster. It has been found that the Great Attractor and all the galaxies in our region of the universe (including our galaxy, the Milky Way) are moving toward the Shapley Supercluster.
In 2017 it was proposed that the movement towards attractors like the Shapley Supercluster attractor creates a relative movement away from underdense areas, that may be visualized as a virtual repeller. This approach enables new ways of understanding and modelling variations in galactic movements. The nearest large underdense area has been labelled the dipole repeller.>>
[quote="Chris Peterson" post_id=315678 time=1628427965 user_id=117706]
[quote=neufer post_id=315667 time=1628388689 user_id=124483]
[quote="Chris Peterson" post_id=315663 time=1628368246 user_id=117706]
I'd say that every point in the Universe has very nearly the same amount of mass surrounding it... both in the observable universe and the Universe as a whole. That is, just as every point can be treated as the geometric center of the 3D universe, so to can it be treated as very close to the center of mass of the Universe. The ability to answer the question lies in our ability to know the topology of the Universe, which appears to be discoverable.[/quote]
[b][i][color=#0000FF]The center of mass of the Universe is at "the Big Bang singularity" in which
space & time lose all meaning because they are just coming into existence.[/color][/i][/b][/quote]
The "singularity" you speak of is not a singularity [i]dimensionally [/i]at all. It is a physical point in the Universe, defined by (0,0,0,0). It is not, however, accessible to us. Which is why I specifically referred to the center of mass of the [i]3D [/i]universe, where (assuming a topologically closed universe... a point that remains unsettled) it is reasonable to treat every 3D point as the center of mass.
[/quote]
Due to light speed time delays of gravitational forces: [b]that (0,0,0,0) physical point in the Universe (along with all the mass & energy between it & us) is the [u]only[/u] Universe accessible to us.[/b] We observe either gravitational decelerations & accelerations with respect to that very (0,0,0,0) physical point (and not any other distant "center of mass").
Note, however, there has also been a natural physical attraction to Shapley Supercluster :eyebrows: local mass concentration:
[quote=https://en.wikipedia.org/wiki/Cosmic_microwave_background#CMBR_dipole_anisotropy_(%E2%84%93_=_1)]
<<The cosmic microwave background (CMB) dipole moment could also be interpreted as the peculiar motion of the Earth toward the CMB. From the CMB data, it is seen that the Sun appears to be moving at 368 ± 2 km/s relative to the reference frame of the CMB (also called the CMB rest frame, or the frame of reference in which there is no motion through the CMB). The Local Group — the galaxy group that includes our own Milky Way galaxy — appears to be moving at 627 ± 22 km/s 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 red shift and blue shift due to motion relative to the CMB.>>[/quote][quote=https://en.wikipedia.org/wiki/Great_Attractor]
[float=left][img3=Panoramic view of the entire near-infrared sky. Norma & the Great Attractor is shown with the long blue arrow at bottom right.]https://upload.wikimedia.org/wikipedia/commons/7/7d/2MASS_LSS_chart-NEW_Nasa.jpg[/img3][/float]
<<The Great Attractor is a gravitational anomaly in intergalactic space and the apparent central gravitational point of the Laniakea Supercluster. The observed anomalies suggest a localized concentration of mass millions of times more massive than the Milky Way. However, it is inconveniently obscured by our own Milky Way's galactic plane, lying behind the Zone of Avoidance (ZOA), so that, in visible light wavelengths, the Great Attractor is difficult to observe directly.
The anomaly is observable by its effect on the motion of galaxies and their associated clusters over a region of hundreds of millions of light-years across the universe. These galaxies are observable above and below the ZOA; all are redshifted in accordance with the Hubble Flow, indicating that they are receding relative to us and to each other, but the variations in their redshifts are large enough and regular enough to reveal that they are slightly drawn towards the anomaly. The variations in their redshifts are known as peculiar velocities, and cover a range from about +700 km/s to −700 km/s, depending on the angular deviation from the direction to the Great Attractor. [b][u][color=#0000FF]The Great Attractor itself is moving towards the Shapley Supercluster.[/color][/u][/b]>>[/quote][quote=https://en.wikipedia.org/wiki/Shapley_Supercluster]
[float=left][img3=Shapley Supercluster with its galaxy members and its intergalactic dark matter halo]https://upload.wikimedia.org/wikipedia/commons/d/da/Shapley_supercluster.png[/img3][/float]
<<[b][u][color=#0000FF]The Shapley Supercluster or Shapley Concentration (SCl 124) 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.[/color][/u][/b] It appears as a striking overdensity in the distribution of galaxies in the constellation of Centaurus. It is 650 million light-years away (z=0.046).
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 cosmic microwave background (CMB) frame of reference. This has led many to speculate that the Shapley Supercluster may indeed be one of the major causes of our galaxy's peculiar motion—the Great Attractor may be another—and has led to a surge of interest in this supercluster. It has been found that the Great Attractor and all the galaxies in our region of the universe (including our galaxy, the Milky Way) are moving toward the Shapley Supercluster.
In 2017 it was proposed that the movement towards attractors like the Shapley Supercluster attractor creates a relative movement away from underdense areas, that may be visualized as a virtual repeller. This approach enables new ways of understanding and modelling variations in galactic movements. The nearest large underdense area has been labelled the dipole repeller.>>[/quote]