Physicists Want to Ditch Dark Energy

Dark energy and dark matter aren't really theories. They are sort of the default solution to a set of problems that exist in cosmology. In a sense, every physicist wants to ditch dark matter or dark energy (or at least our current understandings of them), but they just don't know what to replace them with.

One of the better nautilus articles I’ve read, usually they’re unreadable and boring, despite an interesting title. Unsurprising that it was written by Sabine Hossenfelder. Good science communication is a real skill.

Every science documentary I've watched tells me most physicists want to ditch "dark energy" because it's a placeholder term for something we still don't understand yet. Map-makers didn't actually believe there were dragons after all.

Although i'm not a physicist and i have an average understanding of these things, dark energy and dark matter always felt to me like physicists had created mystical entities with magical properties because they couldn't explain some experimental results.

And my average brain always thought and still thinks that instead of chasing these unicorn entities that still can't be found, maybe we should reconsider some things, as it seems to be the case presented here in this article.

> This theory has it that all types of energy—including matter, radiation, and pressure—curve space, and the curvature in return influences how the energy-types move. The authors of the new paper, led by Antonia Seifert, don’t question this. They question instead how we use Einstein’s math.

This is so fascinating. I think the principle applies to so much of the natural sciences. GR describes a set of rules (differential equations using tensors) that describe how matter moves in spacetime, and how it curves it. But outside of certain specific conditions (Schwarzschild etc), we can't (yet) use it to build useful models! We can use it to an extent to validate parts of models, but it leaves so much to the imagination. We are still using Newtonian models in cosmology, then applying GR effects like GEM piecemeal, and the time dilation effects in the article, where complexity and understanding allow.

We have these rules, but don't know how to use them to model! See also: Quantum mechanics and ab-initio chemistry. It's as if the universe is written in differential equations, but we are novices at how to use them.

Alas, the top hits for "timescape" refer to a sci-fi book.

But timescape wiltshire leads to a nice presentation:

https://www.nottingham.ac.uk/physics/documents/talesoflambda...

And without math, https://en.m.wikipedia.org/wiki/Inhomogeneous_cosmology

> He called it the “timescape.” This is because, in Einstein’s theory, time runs at different speeds depending on the amount of matter that a region contains.

I wonder if he called it "timescape" as a reference to the star trek the next generation episode where small bubbles of space experience time moving at different speeds.

I'm not a physicist but both dark energy and dark matter have a definite whiff of 'luminiferous aether' imho.

Of course they're just placeholders for things we don't understand, but my guess is that they are not any form of energy or matter at all, but a misunderstanding of the geometry of space or something similar.

When you run the Schwarzschild radius calculation for the universe (relating mass of a black hole to event horizon radius) you get a prediction that's close enough to the size of the universe and it's mass, so to me that's pretty good evidence our universe is an event horizon.

This means all 3D points in our space are on the horizon itself, and the time dimension is the normal vector to that "surface" (3D manifold). It explains why space is expanding, because Event Horizons always only expand (excluding considering Hawking evaporation of course, which happens too slowly to affect things)

From the article,

> discovering that the expansion of the universe was accelerating. They came to this conclusion by observing faraway exploding stars. These distant supernovae showed that the cosmos was getting bigger faster because the farther away the supernovae, the faster it appeared to be moving away from us.

This explanation always bothers me. After a long time, things that move faster WILL be farther away than things that move slower. Thats just the definition of speed. It does not, by itself, demonstrate acceleration.

Sabine's video version of the same stuff https://youtu.be/frJy-sSriHM

> In this timescape model, what we observe in our vicinity, in our own patch, is governed by different laws than what happens on average at larger distances. It is much like how what you observe in your home city may be a poor description for what happens in the world on average.

If a dark matter alternative ends up being an accepted theory, then RelMOND stans are gonna be beyond smug, and well rightfully so I suppose.

From https://news.ycombinator.com/item?id=36222625#36265001 :

> Further notes regarding Superfluid Quantum Gravity (instead of dark energy)

Why are these anti-dark matter articles upvoted on hacker news.

As I understand it, most cosmologists still thing dark matter is the most likely candidate as it explains multiple different daya points unlike Mond.

Why don't they want to ditch dark matter? It is more plausible candidate to ditch :)

Ah yes, the “cosmological principle” that everything averages out to be basically the same everywhere over large distances. It makes sense that this principle would need to be violated in order to eliminate dark energy.

One of my favorite sci fi concepts is a universe where the cosmological principle was false.

The submission title is edited in a questionable way. Specially that the original one is not clickbait and does fit in the title letters limit.

There is a world of difference between " These Physicists Want to Ditch Dark Energy " and " Physicists Want to Ditch Dark Energy". One is about new model from some physicists and the other implying a conciseness around ditching dark energy.

edit: I didn't know that there is automatic re-write rules for HN. However the fact that the edited title is clickbait now regardless the reason. Just clarifying in case of this is considered an attack on the submitter.

The truncation of the title to remove "These" does severe violence to its meaning.