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Comment by throwlaplace | Hacker News Reader

that's because experiment drives physics rather than mathematical consistency (no matter how much people pretend it's about "beauty"). plenty of mathematically consistent physical theories have been falsified by experiment and plenty of mathematically inconsistent physical theories have made precise and accurate predictions.

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When was the last time an experiment had a result that wasn’t explained by theory (supralumimal neutrinos aside)?

Observations of the cosmic microwave background, galactic rotation, gravitational lensing, and redshift led to the concepts of "dark matter" and "dark energy" that aren't yet explained by theory.

The cosmic microwave background was first detected in the 1960s, gravitaional lensing was predicted by Einstein in the early 1900s and redshift can be traced back to the later half of the 1800s (as an extension of the Doppler effect)...

It's not the existence of these phenomena that's unexplained, but specific observations that don't fit our current theories.

This article seems like a decent introduction:

https://medium.com/starts-with-a-bang/five-reasons-we-think-...

MOND is a better explanation than dark energy.

There was an article linked here just a week or two ago. Its claim was that the distance measurements used in cosmology may be wrong on larger scales. With the correction there is no need for MOND or dark energy. This needs confirmation of course.

I have yet to see the "expected" galactic rotation curves that are contradicted by observation a lead to ideas about dark MATTER. I'm mean I've seen the curves but cant find the math behind them. You often see weak references to Keplers law which doesnt even apply, so that leaves me very skeptical.

> I'm mean I've seen the curves but cant find the math behind them. You often see weak references to Keplers law which doesnt even apply, so that leaves me very skeptical.

Huh?

This is directly derived from 3rd law

>> This is directly derived from 3rd law

Then it's wrong. I will need to see the derivation to find the error. I've seen indications of a couple possible places it may be (based on simplifying assumptions people make incorrectly) but have not seen the actual derivation of the expected curve.

gimme some time, I'm busy till Jan 20, then I'll redo it. Just in case, kick me a message if I'm not heard from...

MOND has nothing to do with dark energy, and the article suggested nothing about anything addressed in MOND.

MOND is an attempt to make dark matter an unnecessary assumption.

No opinion on whether some MOND will turn out to work better than dark matter.

maybe a bit facetious, but wave-particle duality at a time when we only had classical mechanics...?

Superconduction is still poorly understood. We don't have a good model that predicts what materials are superconductors.

It's likely though that in the case of superconductivity the problem is the complexity of the calculations, rather than a fundamental theoretical problem. It's like protein folding - we're no where near being able to do an ab initio calculation of the shape of a protein, but that doesn't mean that there is a fundamental problem with quantum mechanics.

Some examples: Matter/anti-matter asymmetry, arrow of time direction, why CP violations, neutrino mass questions, why masses are what they are, dark matter and energy nature, what cancels out zero point energy, many structures on universe scale don't fit models, firewall paradox, why is gravity so weak, are there gravitons (other particles..), do magnetic monopoles exist (widely conjectured to work from models, none yet seen), why 3 generations of particles, proton radius discrepancies, exotic and pentaquark (and higher) particles, Navier-Stokes open problems, lots of superconductor and metamaterial questions results not explained theoretically, and so on...

Matter/anti-matter asymmetry is expected to be present. It is a basic feature of individual random walk instances using symmetrical laws that about half will be dominated by matter and the other half dominated by antimatter for long periods of time (although the "universe" may pass through pure energy states as it switches between the two). While there is a balance on average and in the long run, there is not for individual instances or points in time.

We called the dominating one for our current instance/state of the universe "matter": https://physics.stackexchange.com/questions/505662/why-is-ma...

>Matter/anti-matter asymmetry is expected to be present. It is a basic feature of individual random walk

It may be the cause, but it is not known to be the cause.

And it's not a random walk; black holes accumulate charge from pairs, making future radiation not symmetric.

My understanding is that people have probed this for some time and it's still inconclusive if it can generate the observed imbalance. Here's [1] a 1979 paper on the idea, with hundreds of citations, in case you want to poke at the literature.

If I remember, Cosmology by Weinberg has a chapter on various theories of how the imbalance may happen, none of them known to be all of or even part of the answer.

[1] https://journals.aps.org/prd/abstract/10.1103/PhysRevD.19.10...

Nice link, thanks.

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