# Is the Standard Model of Physics Now Broken?
**URL:** https://discourse.peacefulscience.org/t/is-the-standard-model-of-physics-now-broken/13515
**Category:** Conversation
**Tags:** Science
**Created:** [April 8, 2021, 8:18pm UTC](https://discourse.peacefulscience.org/t/is-the-standard-model-of-physics-now-broken/13515 "2021-04-08T20:18:29Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@thoughtful](https://discourse.peacefulscience.org/u/thoughtful)
#### Post date: [April 8, 2021, 8:18pm UTC](https://discourse.peacefulscience.org/t/is-the-standard-model-of-physics-now-broken/13515/1 "2021-04-08T20:18:29Z")
Sabine is very good at telling everyone to calm down. đ I had read another article that quoted a scientist explaining he was so excited he couldnât sleep.
But I thought this was a really helpful explainer about the standard model and physics generally, in case anyone was interested. Sheâs good at that too.
> **[Is the Standard Model of Physics Now Broken?](https://www.scientificamerican.com/article/is-the-standard-model-of-physics-now-broken/)**
>
> The discrepancy between the theoretical prediction and the experimentally determined value of the muon's magnetic moment has become slightly stronger with a new result from Fermilab. But what does it mean?
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### Author:  [@glipsnort](https://discourse.peacefulscience.org/u/glipsnort)
#### Post date: [April 9, 2021, 12:21pm UTC](https://discourse.peacefulscience.org/t/is-the-standard-model-of-physics-now-broken/13515/2 "2021-04-09T12:21:43Z")
20 years for the only real anomaly in particle physics to go from 3.7 sigma to 4.2 sigma â perfectly sums up why I left the field.
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### Author:  [@structureoftruth](https://discourse.peacefulscience.org/u/structureoftruth)
#### Post date: [April 9, 2021, 1:52pm UTC](https://discourse.peacefulscience.org/t/is-the-standard-model-of-physics-now-broken/13515/3 "2021-04-09T13:52:36Z")
I was hoping Sabine would write something about this discovery; thanks for the find @thoughtful ! This helped place the actual significance (no pun intended) of the result in perspective.
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### Author:  [@PdotdQ](https://discourse.peacefulscience.org/u/PdotdQ)
#### Post date: [April 10, 2021, 4:35am UTC](https://discourse.peacefulscience.org/t/is-the-standard-model-of-physics-now-broken/13515/4 "2021-04-10T04:35:39Z")
No, this result does not show that the Standard Model is broken:
1. 4.2 sigma is not that high
2. Itâs 4.2 sigma off from a theoretical calculation that we didnât know whether we did correctly â there are other ways for the calculation to be off than the Standard Model being wrong
But:
There is a myriad of other experiments/observations pointing to the Standard Model being at the very least, incomplete. Most of them are astronomical: dark matter, accelerating expansion of the cosmos, matter-antimatter asymmetry, etc. None of them can conclusively say anything about the SM, but each is evidence against the SM being all there is.
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### Author:  [@John\_Harshman](https://discourse.peacefulscience.org/u/John_Harshman)
#### Post date: [April 10, 2021, 7:40pm UTC](https://discourse.peacefulscience.org/t/is-the-standard-model-of-physics-now-broken/13515/5 "2021-04-10T19:40:17Z")
While we have a physicist or two here: Is it clear that dark matter is composed of particles? Does dark matter interact with other dark matter in any way other than by gravity? Similarly, do dark matter particles have a size, i.e. do they repel each other over some distance? What is the density of dark matter particles around here? Is there even a way to investigate those questions? Etc.
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### Author:  [@PdotdQ](https://discourse.peacefulscience.org/u/PdotdQ)
#### Post date: [April 11, 2021, 3:29am UTC](https://discourse.peacefulscience.org/t/is-the-standard-model-of-physics-now-broken/13515/6 "2021-04-11T03:29:38Z")
> [@John\_Harshman](#):
>
> Is it clear that dark matter is composed of particles?
No. The effects of dark matter on galaxies, for example, could potentially be explained by a modification of the gravitational force. In this theory, âdark matterâ never existed in the first place.
> [@John\_Harshman](#):
>
> Does dark matter interact with other dark matter in any way other than by gravity?
Maybe â there are theories of an extended âdark sectorâ, which involves, for example, âdark electromagnetismâ. In dark electromagnetism, dark matter can interact with other dark matter via âdark photonâ. There is a variety of tests one can conduct to deduce whether dark electromagnetism (or any other âdark forcesâ) is true or not; so far the tests are inconclusive.
> [@John\_Harshman](#):
>
> Similarly, do dark matter particles have a size, i.e. do they repel each other over some distance?
We do not know. Different models of dark matter predict different âsizesâ for the dark matter particle.
> [@John\_Harshman](#):
>
> What is the density of dark matter particles around here?
-) At small scales (i.e., solar system and smaller): we have no idea, again different theories predict different densities
-) At large scales, this can be measured using techniques like âgravitational lensingâ, where the gravity of the dark matter bends light that we can observe with telescopes
-) At extremely large, cosmological scales, the prevailing theory is that it has a density of 0.23 times the âcritical densityâ, where the âcritical densityâ is density required to make the Universe flat (itâs just a number that you can compute)
> [@John\_Harshman](#):
>
> Is there even a way to investigate those questions?
Yes, itâs difficult, but weâre trying our best.
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### Author:  [@system](https://discourse.peacefulscience.org/u/system)
#### Post date: [April 18, 2021, 3:30am UTC](https://discourse.peacefulscience.org/t/is-the-standard-model-of-physics-now-broken/13515/7 "2021-04-18T03:30:19Z")
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