Dark matter + gravity is 'right', or our understanding of gravity is wrong?

In summary, scientists have long debated whether dark matter or a fundamental flaw in our understanding of gravity is the key to explaining the movement of galaxies and other cosmic objects. Recent studies have shown that gravity, as described by Einstein's theory of general relativity, seems to be accurate on large scales. This suggests that dark matter may be the missing piece of the puzzle, as it is the most plausible explanation for the observed discrepancies in gravitational effects. However, the debate continues as researchers work to better understand the nature of dark matter and its role in the universe.
  • #36
weirdoguy said:
Maybe because most people who knows technical details of both dark matter models and alternative models think that dark matter models are better and simpler?

That's it, really. GR as we know it is almost inevitable because of Lovelock's Theorem. In layman's language, it says, basically, if our knowledge of the theory of fields is correct (technically, it is assumed it can be derived from a Lagrangian - a generalisation of ordinary mechanics), Einsteins Equations are inevitable. Of course, we know that GR needs modification at small scales - about the Plank Scale - because of issues with QM. But we even have a quantum theory of gravity thought to be correct to the Plank Scale:
https://blogs.umass.edu/donoghue/research/quantum-gravity-and-effective-field-theory/.
It is also thought the Standard Model breaks down at the Plank Scale - possible even before. So that is nothing new, really.

Anyway, the bottom line is if GR were not true, some longstanding physical principles would have to be wrong. That is indeed possible, but so far, nobody has come up with an alternative that is just so damn elegant, requires so few assumptions and stands up to experimental verification. Lev Landau was fond of saying, 'a rapture on first making one's acquaintance with this theory should, in general, be a characteristic of any born theoretical physicist.'

Thanks
Bill
 
<h2>1. What is dark matter and why is it important?</h2><p>Dark matter is a hypothetical type of matter that is thought to make up about 85% of the total matter in the universe. It does not interact with light, which is why it is "dark" and difficult to detect. Its existence is important because it helps explain the observed gravitational effects on galaxies and galaxy clusters that cannot be accounted for by visible matter.</p><h2>2. How does dark matter relate to our understanding of gravity?</h2><p>Dark matter is thought to interact with gravity in the same way as visible matter, meaning it is affected by and exerts gravitational forces. Our current understanding of gravity, based on Einstein's theory of general relativity, is able to accurately describe the behavior of visible matter. However, the presence of dark matter suggests that there may be more to the story and our understanding of gravity may need to be revised.</p><h2>3. How do scientists study dark matter?</h2><p>Scientists study dark matter through indirect methods, such as observing its gravitational effects on visible matter, or through direct detection experiments using specialized instruments. They also use computer simulations and mathematical models to better understand its properties and distribution in the universe.</p><h2>4. What evidence supports the idea that dark matter exists?</h2><p>There is a wealth of evidence that supports the existence of dark matter. This includes observations of the rotation of galaxies, gravitational lensing, and the distribution of matter in the universe. Additionally, the standard model of cosmology, which is based on a combination of observations and theoretical predictions, includes dark matter as a necessary component to explain the structure and evolution of the universe.</p><h2>5. Could our understanding of gravity be completely wrong?</h2><p>While it is possible that our current understanding of gravity may need to be revised or refined, it is unlikely that it will be completely wrong. Einstein's theory of general relativity has been extensively tested and has accurately predicted a wide range of phenomena. However, it is possible that there may be certain situations, such as at very small scales or in extreme environments, where our current understanding may not fully apply and may need to be modified.</p>

1. What is dark matter and why is it important?

Dark matter is a hypothetical type of matter that is thought to make up about 85% of the total matter in the universe. It does not interact with light, which is why it is "dark" and difficult to detect. Its existence is important because it helps explain the observed gravitational effects on galaxies and galaxy clusters that cannot be accounted for by visible matter.

2. How does dark matter relate to our understanding of gravity?

Dark matter is thought to interact with gravity in the same way as visible matter, meaning it is affected by and exerts gravitational forces. Our current understanding of gravity, based on Einstein's theory of general relativity, is able to accurately describe the behavior of visible matter. However, the presence of dark matter suggests that there may be more to the story and our understanding of gravity may need to be revised.

3. How do scientists study dark matter?

Scientists study dark matter through indirect methods, such as observing its gravitational effects on visible matter, or through direct detection experiments using specialized instruments. They also use computer simulations and mathematical models to better understand its properties and distribution in the universe.

4. What evidence supports the idea that dark matter exists?

There is a wealth of evidence that supports the existence of dark matter. This includes observations of the rotation of galaxies, gravitational lensing, and the distribution of matter in the universe. Additionally, the standard model of cosmology, which is based on a combination of observations and theoretical predictions, includes dark matter as a necessary component to explain the structure and evolution of the universe.

5. Could our understanding of gravity be completely wrong?

While it is possible that our current understanding of gravity may need to be revised or refined, it is unlikely that it will be completely wrong. Einstein's theory of general relativity has been extensively tested and has accurately predicted a wide range of phenomena. However, it is possible that there may be certain situations, such as at very small scales or in extreme environments, where our current understanding may not fully apply and may need to be modified.

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