So I had a hypothesis about why dark matter exists, but seeing as I've just barely begun studying astrophysics its most likely chock full of misconceptions and oversights. Here's a diagram of the idea and an explanation below.

Image depicting model of dark matter, top image is side view of 2D representation of a 2 object system resting on the fabric of spacetime in the third dimension and the bottom image is a top view of the 2D representation

So the top image shows a 3 dimensional representation of spacetime. The star is bending spacetime allowing the planet to orbit it along with the dark matter (they should also be bending it but I was too lazy to draw it. So these objects only exist in the 2D universe shown below if they intersect with the universe and a cross section of it exists within that universe. So if the dark matter falls below the universe, not intersecting it, then it wouldn't be perceptible to them but still would cause an overall increase in mass and changes the orbits of the objects around it. So if you scaled this up to the third and fourth dimension, would this still be applicable or is it just inherently flawed?

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    $\begingroup$ The only thing we know for sure of what Dark Matter actually is is that it is a gravitational phenomenon. We know more about what it isn't than what it is. It exists as an abstract name for baryonic (visible) matter moving in manners inconsistent with our understandings of physics. Current best models explain it as a type of matter/particle that doesn't interact electromagnetically. It could be invisible stuff. It also could be gravity changes on larger scales. It could be new physics entirely. It can be a combination of these unknowns. $\endgroup$
    – David S
    Commented Oct 6, 2023 at 22:29

1 Answer 1


Sorry, but this is not correct. In the diagram, spacetime and hence the universe is the curved line. The sun, Earth, and any dark matter are not on spacetime, they are in it.

Visualising spacetime as a rubber sheet is simple metaphor, but it doesn't really describe how gravity works. And it quickly leads to confusion like this if you think it is really what Relativity is.

Dark matter is invisible because it doesn't interact with light or the electromagnetic field. So it can't form compact structures (like a ball of dark matter)


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