Change law of gravitation to remove dark energy and dark matter

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Discussion Overview

The discussion revolves around the proposition of modifying the law of gravitation, specifically the inverse square law (F = 1/r^2), to address phenomena attributed to dark energy and dark matter. Participants explore the implications of such changes on existing measurements and theories, questioning the validity of current models and the nature of gravitational forces.

Discussion Character

  • Debate/contested
  • Exploratory
  • Technical explanation

Main Points Raised

  • Some participants suggest changing the law of gravitation to include a repulsive force to account for the observed speeds of stars in the outer solar system and the accelerating expansion of galaxies.
  • Others argue that such modifications could violate established measurements, including those related to dark energy, as inferred from red and blue shifts in the cosmic microwave background (CMB).
  • There is mention of alternate gravity theories, with some participants noting that none seem to fully satisfy all observational data.
  • Some participants question the interpretation of galaxies that appear to behave as predicted without dark matter, suggesting that modified gravity theories might explain these observations.
  • Concerns are raised about the terminology used, with discussions on the distinction between "laws" and "theories" in physics, and whether laws can be changed or are merely superseded by new theories.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the modification of gravitational laws and the implications for dark matter and dark energy. There is no consensus on the validity of proposed changes or the interpretation of observational data.

Contextual Notes

Participants highlight limitations in understanding the implications of modifying gravitational laws, including potential conflicts with existing measurements and the need for clarity in terminology regarding laws versus theories.

Who May Find This Useful

This discussion may be of interest to those exploring alternative theories of gravity, the nature of dark matter and dark energy, and the philosophical implications of scientific terminology in physics.

Alain De Vos
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The speed of star on the outer of are solar system is not according to the visible mass.
Change the law of gravitation F = 1/r^2 to fix this.
Galaxies far away are moving away with increasing speed.
Change the law of gravitation F = 1/r^2 to fix this, include a repulsive force to fix.
Would this fix violate other measurements , which ones ?
 
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Alain De Vos said:
Would this fix violate other measurements , which ones ?
Yes. If I understood it correctly, then dark energy can be measured by red and blue shifts of photons leaving / falling into the gravitational potentials in the CMB. That gravitation works as we think it does is proven by the visible matter and energy. The computer models with dark matter match the real world. However, I am not certain that this is a reliable description, my source was pop science.
 
There are plenty of alternate gravity theories. I don't think any of them are completely satisfactory - they can explain some things but not others.
 
Alain De Vos said:
The speed of star on the outer of are solar system is not according to the visible mass.
Change the law of gravitation F = 1/r^2 to fix this.
Galaxies far away are moving away with increasing speed.
Change the law of gravitation F = 1/r^2 to fix this, include a repulsive force to fix.
Would this fix violate other measurements , which ones ?
See, for example:

https://en.wikipedia.org/wiki/Modified_Newtonian_dynamics
 
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fresh_42 said:
Yes. If I understood it correctly, then dark energy can be measured by red and blue shifts of photons leaving / falling into the gravitational potentials in the CMB.
I think you are thinking of the integrated Sachs-Wolfe effect, which is a result of dark energy modifying the gravitational potential wells of galaxy clusters, causing a change in the redshift of CMB photons as they pass through. This is not the same as the Sachs-Wolfe effect, which is derived from properties of the CMB alone.
 
Alain De Vos said:
The speed of star on the outer of are solar system is not according to the visible mass.

What are you referring to here? Do you mean galaxy rotation curves? Our solar system is not a galaxy.
 
Alain De Vos said:
Change the law of gravitation F = 1/r^2 to fix this.

What proposed model are you referring to? Can you give a reference?
 
Didn’t they find some galaxies with no dark matter that behaved just like existing theory would predict?
 
BWV said:
Didn’t they find some galaxies with no dark matter that behaved just like existing theory would predict?
Yeah - but...
How do they detect whether galaxies have dark matter or not, except by how the stars behave?
 
  • #10
DaveC426913 said:
Yeah - but...
How do they detect whether galaxies have dark matter or not, except by how the stars behave?
right, but observations of several galaxies behaving as theory would predict without needing dark matter supports the existence of dark matter and puts the kibosh on (some,most,all?) alt gravity hypothesis
 
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  • #11
BWV said:
Didn’t they find some galaxies with no dark matter that behaved just like existing theory would predict?
From previous discussion on here I gather that some modified gravity theories can handle that. Something to do with long-range effects from nearby galaxies, or something - I don't know the details.
 
  • #12
Alain De Vos said:
Change the law of gravitation F = 1/r^2 to fix this.
How do you want to change the laws? If there are any physics laws, and they are laws, they aren't changable. I have also read that the others that these laws are hipotetical and have something wrong. If we are speaking about something not fixed, we are speaking about teories, not laws. I think that here there is a misundrstanding
 
  • #13
vincenzosassone said:
I think that here there is a misundrstanding
Both "laws" and "theories" are words for things we've invented. We don't generally regard either as being changed, but we certainly develop newer theories (nothing new tends to get called a law these days) which supersede them.
 
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  • #14
Ibix said:
There are plenty of alternate gravity theories.

And the OP has not said which one he is asking about, which means we have no valid basis for discussion.

Thread closed.
 

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