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wolram
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Do we need more proof of dark matter than this?:
https://en.wikipedia.org/wiki/Weak_gravitational_lensing
https://en.wikipedia.org/wiki/Weak_gravitational_lensing
Apparently, since all of that has been known for some time and still dark matter is not 100% guaranteed to not be MOND. I thought the Bullet Cluster was enough evidence against MOND but more knowledgeable folk than me think otherwise.wolram said:Do we need more proof of dark matter than this?:
https://en.wikipedia.org/wiki/Weak_gravitational_lensing
It turns out that when you only have one general class of evidence for a model (in this case, gravitational interactions), it's remarkably difficult to completely rule out alternative explanations. My understanding is that alternatives to dark matter are not very well-motivated by theory and tend to be much more complicated than many WIMP models. It also turns out to be much harder to get a modified gravity theory to work well with CMB, galaxy clusters, and galaxies using the same parameters (MOND has always had difficulty fitting CMB and cluster data).phinds said:Apparently, since all of that has been known for some time and still dark matter is not 100% guaranteed to not be MOND. I thought the Bullet Cluster was enough evidence against MOND but more knowledgeable folk than me think otherwise.
Dark matter is a type of matter that makes up about 85% of the total matter in the universe. It does not emit or absorb light, making it invisible to traditional telescopes. Its presence is inferred through its gravitational effects on visible matter.
Weak gravitational lensing is the distortion of light from distant galaxies as it passes through the gravitational field of dark matter. By studying this lensing effect, scientists can map out the distribution of dark matter in the universe, providing evidence for its existence.
Scientists use a variety of techniques to study weak gravitational lensing, including photometric and spectroscopic surveys, galaxy shape measurements, and simulations. These methods allow them to measure the distortion of light from distant galaxies and map out the distribution of dark matter.
In addition to weak gravitational lensing, there are several other lines of evidence that support the existence of dark matter. These include the rotation curves of galaxies, the gravitational lensing of clusters of galaxies, and the cosmic microwave background radiation.
The study of dark matter is crucial to our understanding of the universe and its evolution. It helps explain the formation and structure of galaxies and galaxy clusters, and provides insights into the overall composition and expansion of the universe. It also plays a key role in the development of theories such as the Big Bang and inflationary models.