Is Dark matter an optical illusion?

In summary, the main evidence for the existence of dark matter is the flat rotation curve of galaxies and high peculiar velocities of galaxies in galaxy clusters. The mass enclosed in a radius R is calculated using the Keplerian equation M(R) = v2R/G. Additionally, gravitational lensing is also a known phenomenon. When plotting galactic rotation curves, it is important to take into account the effect of gravitational lensing, where the trajectory of a photon is bent due to gravitational pull, leading to the observer perceiving the star as farther away from the galactic center and appearing larger than it actually is. This has consequences such as all massive celestial objects appearing larger than they actually are and the farther away the object is, the stronger the magnification
  • #1
Zimbler Igor
1
0
The main evidence for the existence of dark matter is the flat rotation curve of galaxies, and high peculiar velocities of galaxies in galaxy clusters.

GalaxyRotationCurve.png


The mass eclosed in a radius R is derived from the Keplerian equation M(R) = v2R/G .

Also we know about the existence of gravitational lensing.
GravitationalLensingScenario.png

My question is this: was gravitational lensing taken into account when galactic rotation curves were plotted? Because here is an effect of gravitational lensing that I didn`t find mention of:
GL.png


The photon emmited by the star can`t travel directly to the observer because it is gravitationally pulled to the center of the galaxy, so its trajectory is bent. And because of this bending effect the observer will see the star as being farther away from the galactic center. This in turn will push the observer to the conclusion that there is more mass enclosed in the observed radius. If the orbital speed of the star is not calculated from it’s red shift then it will also appear to be bigger then it actually is, since v = w*r, where w – angular velocity, r – observed radius.Consequences:1) All massive celestial objects appear greater then they actually are.2) The farther away the celestial object from the observer the stronger the magnification effect.

GL2.png


3) Most of the distant celestial object that we observe are not actually in the direction that we observe them.

GL3.png


P.S.: The fish is also distorted

Cat_looking_at_fish_in_a_bowl.jpg
 
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  • #2
No, dark matter is not an optical illusion. Since we don't deal with speculation and personal theories here at PF, thread locked.
 

1. What is dark matter?

Dark matter is a hypothetical form of matter that is believed to make up about 85% of the total matter in the universe. It does not emit or absorb light, making it invisible to telescopes and other instruments. Its existence is inferred through its gravitational effects on visible matter.

2. How do we know that dark matter is not just an optical illusion?

Scientists have used various methods to study the effects of dark matter on the motion of galaxies and clusters of galaxies. These studies have consistently shown that there is a significant amount of mass present that cannot be accounted for by visible matter. Additionally, the effects of dark matter can be observed through gravitational lensing, where the mass of dark matter bends light from distant galaxies.

3. Is dark matter the same as black holes?

No, dark matter and black holes are two separate concepts. Black holes are objects with such strong gravitational pull that even light cannot escape from them. Dark matter, on the other hand, is a type of matter that does not interact with light. While black holes can contribute to the overall mass of a galaxy, they are not believed to make up a significant portion of dark matter.

4. How is dark matter different from dark energy?

Dark matter and dark energy are both hypothetical concepts used to explain different observations in the universe. While dark matter is believed to make up the majority of the mass in the universe and affects the motion of galaxies, dark energy is thought to be responsible for the accelerating expansion of the universe.

5. Can we ever directly observe dark matter?

As of now, we do not have the technology or methods to directly observe dark matter. However, scientists are continuously working on experiments and theories to better understand dark matter and potentially find ways to directly detect it. Some proposed methods include using underground detectors or studying the effects of dark matter collisions in space.

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