4 ms·

An Unfolding Scientific Revolution in Cosmology

28 points by matusp 9mo ago

d_silin 9mo ago
Some critical feedback https://www.reddit.com/r/AskPhysics/comments/1lj2k88/comment/mzh3ngy/?context=3 https://www.reddit.com/r/AskPhysics/comments/1lj2k88/comment...
jfengel 9mo ago
Tl;dr it's MOND again.
- deleted 9mo ago
  [deleted]
- jmclnx 9mo ago
  I has to look it up, yes I remember MOND now, thanks For others: https://en.wikipedia.org/wiki/Modified_Newtonian_dynamics https://en.wikipedia.org/wiki/Modified_Newtonian_dynamics
- damnitbuilds 9mo ago
  The preamble was so long, I actually gave up and came here for a TL;DR, and here it is ! :-D Why do some people write blogs as if they're still being paid per word ?!
fpoling 9mo ago
Even Wikipedia article [1] on the rotation curves mentioned that those could be explained if one stops using Newtonian mechanics and rather try to use the full equations of General Relativity. Basically it turned out on the galaxy scale one could not use Newtonian approximation. GR equations are highly non-linear and even tiny non-Newtonian effects accumulates. Then there are various articles pointing out that taking into account that galaxies are filled with plasma can also explain observed results. [1] - https://en.wikipedia.org/wiki/Galaxy_rotation_curve https://en.wikipedia.org/wiki/Galaxy_rotation_curve
ddellacosta 9mo ago
> In hindsight, the ‘seemingly’ part is key. When astronomers first gazed beyond the solar system, they noticed systematic deviations from the predictions of Newtonian gravity. Most scientists assumed that the problem was due to missing mass. But today, there is mounting evidence that this hypothesis is false, and that the observed discrepancy is caused by a breakdown of Newtonian physics. However, like the geocentric model of antiquity, the dark-matter paradigm lumbers on as the dominant belief, largely unfazed by the challenging evidence. Yeah given that this blog is about "new ideas in economics and the social sciences" I was already feeling a bit skeptical, but when I got to this point and saw no mention of https://en.wikipedia.org/wiki/Bullet_Cluster https://en.wikipedia.org/wiki/Bullet_Cluster (I did not bother looking at the 4-year-old video linked to in that paragraph), I had to put this piece down. I subscribe to a number of astronomy youtubers and I have not heard anyone with data to back them up making this assertion. As a counterpoint example, here's Dr. Becky (https://www.physics.ox.ac.uk/our-people/smethurst https://www.physics.ox.ac.uk/our-people/smethurst) from ~4 months ago obviously not coming from the perspective that dark matter is being ruled out, and right out of the gate she refers back to another piece talking about why we are (so far) convinced dark matter is legitimate: https://www.youtube.com/watch?v=lyyZzzgoLNE https://www.youtube.com/watch?v=lyyZzzgoLNE So, yeah, as jfengel says...this seems like more MOND again from a dilettante. Skip it
- SJC_Hacker 9mo ago
  I heard the perspective from one astronomer that "dark matter" isn't a theory so much as an observation (and same goes for dark energy)
  - ddellacosta 9mo ago
    Heh https://www.youtube.com/watch?v=PbmJkMhmrVI https://www.youtube.com/watch?v=PbmJkMhmrVI

28 points by matusp 9mo ago

Some critical feedback https://www.reddit.com/r/AskPhysics/comments/1lj2k88/comment/mzh3ngy/?context=3 https://www.reddit.com/r/AskPhysics/comments/1lj2k88/comment...

jfengel 9mo ago

Tl;dr it's MOND again.

deleted 9mo ago
[deleted]
jmclnx 9mo ago
I has to look it up, yes I remember MOND now, thanks For others: https://en.wikipedia.org/wiki/Modified_Newtonian_dynamics https://en.wikipedia.org/wiki/Modified_Newtonian_dynamics
damnitbuilds 9mo ago
The preamble was so long, I actually gave up and came here for a TL;DR, and here it is ! :-D Why do some people write blogs as if they're still being paid per word ?!

fpoling 9mo ago

Even Wikipedia article [1] on the rotation curves mentioned that those could be explained if one stops using Newtonian mechanics and rather try to use the full equations of General Relativity. Basically it turned out on the galaxy scale one could not use Newtonian approximation. GR equations are highly non-linear and even tiny non-Newtonian effects accumulates. Then there are various articles pointing out that taking into account that galaxies are filled with plasma can also explain observed results. [1] - https://en.wikipedia.org/wiki/Galaxy_rotation_curve https://en.wikipedia.org/wiki/Galaxy_rotation_curve

ddellacosta 9mo ago

> In hindsight, the ‘seemingly’ part is key. When astronomers first gazed beyond the solar system, they noticed systematic deviations from the predictions of Newtonian gravity. Most scientists assumed that the problem was due to missing mass. But today, there is mounting evidence that this hypothesis is false, and that the observed discrepancy is caused by a breakdown of Newtonian physics. However, like the geocentric model of antiquity, the dark-matter paradigm lumbers on as the dominant belief, largely unfazed by the challenging evidence. Yeah given that this blog is about "new ideas in economics and the social sciences" I was already feeling a bit skeptical, but when I got to this point and saw no mention of https://en.wikipedia.org/wiki/Bullet_Cluster https://en.wikipedia.org/wiki/Bullet_Cluster (I did not bother looking at the 4-year-old video linked to in that paragraph), I had to put this piece down. I subscribe to a number of astronomy youtubers and I have not heard anyone with data to back them up making this assertion. As a counterpoint example, here's Dr. Becky (https://www.physics.ox.ac.uk/our-people/smethurst https://www.physics.ox.ac.uk/our-people/smethurst) from ~4 months ago obviously not coming from the perspective that dark matter is being ruled out, and right out of the gate she refers back to another piece talking about why we are (so far) convinced dark matter is legitimate: https://www.youtube.com/watch?v=lyyZzzgoLNE https://www.youtube.com/watch?v=lyyZzzgoLNE So, yeah, as jfengel says...this seems like more MOND again from a dilettante. Skip it

SJC_Hacker 9mo ago
I heard the perspective from one astronomer that "dark matter" isn't a theory so much as an observation (and same goes for dark energy)
- ddellacosta 9mo ago
  Heh https://www.youtube.com/watch?v=PbmJkMhmrVI https://www.youtube.com/watch?v=PbmJkMhmrVI