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With the expansion of the universe, all objects far away from us appear to be moving away (ie: exhibit Redshift). With distance, this acceleration / redshift also seems to increase (~73,000 (m/s) / (1,000,000 parsecs)). The general trend across all observations also seems to be accelerating.

Could this be because the frame of reference of the observer is changing? ie: "I'm falling into a well, but from my own perspective it looks like the sky is falling away from me." The obvious candidate being a gravity well, where distortion affects objects falling at different locations and velocities differently. "The sky looks like its falling away faster the further away it is." And the entire process appears to be accelerating. Also sounds like falling.

Except, from the perspective of the observer it is not obvious the observer exists within a black hole, because the creature was born within the black hole, and the falling time scales (from the perspective of a livable object like a planet) are so long that most organisms live and die without noticing?

Question: Could be we (as a society) be falling into a black hole and instead correlate it as "expanding universe everywhere".

Edit: Other thoughts on this. The Great Attractor and the direction of the Dark Flow both appear to also point in a zone behind the Zone of Avoidance directly within the Milky Way's galactic plane. The orientation then looks like a long line of larger and larger attractors.

Edit2: Added an image to respond to justhalf comment below, and also illustrate view distortion outside the "die immediately" zone. Note, if you were born in the second situation, the star field still looks "normal", just contracted compared to what you'd see otherwise. Starfield With and Without Distortion

And a further image with 2D curvature illustration and verbal description.

Curvature Illustration 2D

If there were many layers of this type of effect nested, then they would all have this layered "distort your vision towards a dot / point" effect. Second image is taken from the header of this Science News Article and modified for my topic.

Edit3: From @dominicf below in comments "new speculative article with a similar focus here: livescience.com/space/could-earth-be-inside-a-black-hole"

From the article "A black hole looks very much like the Big Bang in reverse. … The math looks similar." G. Khanna, U. Rhode Island.

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    $\begingroup$ it certainly feels like it sometimes... $\endgroup$
    – uhoh
    Jun 16, 2023 at 0:01
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    $\begingroup$ I could be wrong, but I think I read that in general it's actually very hard to fall into any gravity well. Like it's even very hard to fly straight to our sun. Because you could only do it if you are flying in a straight line towards it. Any other direction will put you in orbit. $\endgroup$
    – Ivo
    Jun 16, 2023 at 6:59
  • $\begingroup$ Does it mean the universe is expanding in a velocity of 73,000 m/s each 1,000,000 parsecs? $\endgroup$ Jun 16, 2023 at 10:36
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    $\begingroup$ @SnackExchange For the S.I.-inclined and otherwise curious, 73,000 m/s/Mpc = 2.366 aHz. $\endgroup$ Jun 16, 2023 at 16:01
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    $\begingroup$ I just stumbled upon a new speculative article with a similar focus here: livescience.com/space/could-earth-be-inside-a-black-hole $\endgroup$
    – dominecf
    Jun 20, 2023 at 9:47

2 Answers 2

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No.

There are two ways of understanding your question. One is "could there be a nearby, relatively small black hole (say, a few million times the mass of the sun) into which we are falling.

No, there isn't, we would see it. The gravitational effects are localised about a the black hole, matter falling into it would heat up and emit X-rays, it would disrupt the motion of other nearby stars. It wouldn't create an "expanding universe" effect, since it's gravity is only local, it would have no measurable effect on distant galaxies. It would be strongly asymetric: we would be falling in one direction, which would not cause more distant galaxies to appear to be moving faster than more local ones.

Alternatively you could be asking "is there a universal black hole into which the observable universe will collapse.

Again the answer is no, but this comes with a slight caveat. If the universe is falling into a black hole then it would appear to be contracting. That is the opposite of what we see. It is possible that the universe could expand and then contract, if the mass in the universe is sufficient. It seems that that isn't the case. The mass (including dark energy) is not sufficient to cause the universe to collapse, so it will go on expanding forever, and there is no singularity in our future.

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    $\begingroup$ (Dunno whether you might care, so I did not directly edit, but, if you want to have things be good "for the record": typos "asymmetric" and "alternatively"... Thanks for all your astute answers and comments!) $\endgroup$ Jun 15, 2023 at 21:35
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    $\begingroup$ I don't believe my question points toward the first idea. Although that requires some consideration. On the second, why contracting? We see objects that appear to move away from us. And appear to move away faster further away. If I am born on a planet already in the process of "falling", all objects less accelerated, or "above", will appear to be accelerating away. Further away, less acceleration toward point collapse, so greater apparent acceleration away. Objects "below" appear opposite, yet this area would have greater and greater congestion of view, because of the point collapse. $\endgroup$
    – G. Putnam
    Jun 15, 2023 at 21:57
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    $\begingroup$ contracting because if the whole universe is falling into a black hole, then in the future things that are currently far away will be closer to use (because they are falling into the black hole) and that is the definition of contraction. $\endgroup$
    – James K
    Jun 15, 2023 at 22:07
  • $\begingroup$ @JamesK I guess the question here is that in the case we are falling "faster" than the outer one, the outer one would appear to be expanding (especially given the well analogy in OP question). This would require earth-centric black hole, though $\endgroup$
    – justhalf
    Jun 16, 2023 at 3:33
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    $\begingroup$ Or more likely we wouldn't see it because we'd all have been spaghettified to death long before. Black holes aren't nice things to be around if you want your atoms to stick together... $\endgroup$ Jun 16, 2023 at 14:08
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If a system is falling into (or orbiting) some large mass, like a black hole, it experiences tidal forces. Particles closer to the gravitating mass are pulled toward it more strongly, while particles farther from the mass are pulled less strongly. Thus, the system gets stretched along the radial direction from the gravitating mass. And moreover, this stretching is precisely in accordance with Hubble's law, because the tidal force on an object is proportional to its radial position! (At least in the limit that the system under consideration is small compared to its distance from the gravitating mass.)

However, instead of the radial direction, consider a tangential direction. Specifically, consider two objects at the same distance from the gravitating mass, but at different positions. They are both pulled toward the gravitating mass. A component of that force lies along the line between the two objects; thus they are pulled toward each other. Tidal forces thus cause contraction, not expansion, along the tangential directions.

Thus, if cosmic expansion were due to falling into an enormous gravitating object, it would be highly anisotropic, with expansion along one axis and contraction along the other two. In contrast, we observe the Universe to be expanding isotropically (at the same rate in every direction).

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  • $\begingroup$ I think my argument, is that what you call isotropic, I call anisotropic, specifically because of the viewable distortion that appears to change with distance. The reason it appears uniform is because with a nested array of larger and larger distortions, all the distortions would curve the view, and cause an effect like they're all right below each other. Why the Great Attractor seems to be right behind the Milky Way, because our view is already distorted toward the galactic center, and then all view in the MW is then distorted toward the Great Attractor. $\endgroup$
    – G. Putnam
    Jun 16, 2023 at 19:34
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    $\begingroup$ @G.Putnam Keep in mind cosmic expansion is measured by redshifts, not by things looking like they are motion-blurred (looking at the image you edited in) or distorted in whatever other way. In fact the Universe looks incredibly homogeneous and isotropic at large scales, so if your model predicts large-scale visual distortions, that is a problem. Anyway, the pattern of redshifts/blueshifts from falling toward a massive object would also be highly anisotropic. $\endgroup$
    – Sten
    Jun 16, 2023 at 20:34
  • $\begingroup$ Thanks for the reply. Not trying to imply motion blur with the image. Artifact of editing process, and why I included 2nd image. The stars would be too much point sources to show blur. Just wanted to show stars apparent position being distorted similar to 2nd image. My impression, would be that space would be bent enough, especially with a long chain of larger and larger distortions falling into each other (extension of 2nd image), that the effect from the 3rd, or 4th well might be so enormous, that space would look effectively spherically isotropic, because your view is curved. $\endgroup$
    – G. Putnam
    Jun 17, 2023 at 17:57

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