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No, negative masses have not revolutionized cosmology

backreaction.blogspot.com

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Re: No, negative masses have not revolutionized cosmology

#41

Post by rwilson4 »

mbell wrote: post #14

I'm not a physicist, just an interested bystander but some of these arguments don't seem to hold water to me: > There’s a more general point to be made here. The primary reason that we use dark matter and dark energy to explain cosmological observations is that they are simple. > A creation term is basically a magic fix by which you can explain everything and anything. Dark matter is an unknown 'substance' that inter…

I believe the author's argument is: however simple or complicated dark matter and energy are, negative (inertial) mass just makes things even more complicated, without offering any new (testable) insights. The author herself points out that she (and the GR community) may be wrong about a lot of this stuff (e.g. that gravity is mediated by a spin-2 field), but absent a testable hypothesis, negative masses don't actually move the field forward at all.

Seemingly "crazy" ideas sometimes turn out to be correct! But in science, we demand radical ideas at least make testable hypotheses.

Re: No, negative masses have not revolutionized cosmology

#42

Post by JumpCrisscross »

apo wrote: post #36

Can't help but think of phlogiston: Eventually, quantitative experiments revealed problems, including the fact that some metals gained mass when they burned, even though they were supposed to have lost phlogiston. Some[who?] phlogiston proponents explained this by concluding that phlogiston had negative weight; https://en.wikipedia.org/wiki/Phlogiston_theory Eventually, the mass paradox was resolved by the realizatio…

Side note: it’s pretty incredible how phlogiston theory correctly linked burning and rusting, despite being unaware of oxidation. (Also, that plants have a part to play in the oxidation-carbon cycle.)

I don’t know if oxygen theory would have developed without phlogiston theory first linking these phenomena.

Re: No, negative masses have not revolutionized cosmology

#43

Post by simonh »

mbell wrote: post #14

I'm not a physicist, just an interested bystander but some of these arguments don't seem to hold water to me: > There’s a more general point to be made here. The primary reason that we use dark matter and dark energy to explain cosmological observations is that they are simple. > A creation term is basically a magic fix by which you can explain everything and anything. Dark matter is an unknown 'substance' that inter…

I don’t know about dark matter, but the case for dark energy or something like it is pretty compelling. The expansion of the universe is accelerating. Things don’t generally accelerate unless there is something pushing them. So what is it that’s pushing everything in the universe apart?

Maybe it isn’t a ‘thing’ doing it, who knows, but there must be a reason.

Re: No, negative masses have not revolutionized cosmology

#44

Post by narrator »

simonh wrote: post #40
narrator wrote: post #37

Earlier quoted context omitted.

The Egyptians and Babylonians didn't really technologically advance much for 1000 years. They placed the most emphasis in their society on maintaining the social order above all else. Progress can be stopped if you interfere properly with disruptive advances in science. Much of the world is still trying to roll back the development and widespread dissemination of small arms technology because it interferes too much w…

It’ll keep scientists in the countries that do this from discovering such weapons. Meanwhile elsewhere in the world...

What if they've already developed these weapons, but don't find it useful to let the rest of the world know about them? For example, there's the mystery of the very real, but unexplained brain injuries to diplomats at the U.S embassies in China and Cuba.

Re: No, negative masses have not revolutionized cosmology

#45

Post by rwilson4 »

jetrink wrote: post #39
throwawaymath wrote: post #35

Earlier quoted context omitted.

> As I read that paragraph, I thought to myself that the author should read Sabine Hossenfelder's recent book Lost in Math: How Beauty Leads Physics Astray. The author is Sabine Hossenfelder :)

I realized when I reached the bottom of the post. It is odd to me to see her saying that the new theory is disqualified for not being as simple as alternatives after reading her book.

It's not disqualified for not being simple, it's disqualified for not making testable predictions. Given two theories, neither of which make testable predictions, the simpler one (and the one that has been studied more thoroughly) is the more reliable.

Otherwise, why not just say that the missing mass is unicorns? And the energy driving the accelerated expansion of the universe is the energy of their love? There's no shortage of radical explanations for dark mass/energy. The scientific community takes them seriously to the extent that they are compatible with past observations and make testable hypotheses that distinguish them from other theories.

Re: No, negative masses have not revolutionized cosmology

#46

Post by zwkrt »

danharaj wrote: post #38
garmaine wrote: post #20

Earlier quoted context omitted.

Dark energy is the cosmological constant introduced by Einstein. So that criticism is rather ironic.

Actually, a cosmological constant is derivable from the Standard Model. But it's off by a very remarkable amount. Dark energy is the observation that that the Standard Model mispredicts the cosmological constant, so there must be something wrong with it.

Also known as the Vacuum Catastrophe, "the largest discrepancy between theory and experiment in all of science".

https://en.wikipedia.org/wiki/Vacuum_catastrophe

Re: No, negative masses have not revolutionized cosmology

#47

Post by vanderZwan »

eutropia wrote: post #33
vanderZwan wrote: post #30

Earlier quoted context omitted.

> Tone of this blog post is extremely pedantic and comes across as if the author were personally insulted by the paper. I suspect she is insulted, but more so by the press release surrounding a new paper unconfirmed by experimentation. That is now how science works. One could say it's like calling a buggy alpha version of a software project a stable finished product, if we pretended people actually did give a damn ab…

Yeah the press release and subsequent science journalism is all annoying and breathless and overblown -- totally agreed. But to say that its unconfirmed by experimentation and "not how science works" is a bit silly, don't you think? The paper proposes a model, shows outputs of the model, and demonstrates how it predicts things we have already observed. It's a good starting point for other experiments and observations…

> But to say that its unconfirmed by experimentation and "not how science works" is a bit silly, don't you think?

No, because she is not saying that the paper is rubbish, she is addressing the hype among an uninformed public and telling them to chill.

Re: No, negative masses have not revolutionized cosmology

#48

Post by lisper »

mbell wrote: post #23
garmaine wrote: post #20

Earlier quoted context omitted.

Dark energy is the cosmological constant introduced by Einstein. So that criticism is rather ironic.

Maybe? We don't know, also Einstein wasn't a fan: > Einstein originally introduced the concept in 1917 [2] to counterbalance the effects of gravity and achieve a static universe, a notion which was the accepted view at the time. Einstein abandoned the concept in 1931 after Hubble's discovery of the expanding universe. > Einstein reportedly referred to his failure to accept the validation of his equations—when they ha…

It was actually a double-blunder. Einstein missed the opportunity to predict the expanding universe (and, as a corollary, the big bang). And then, when it turned out the universe was expanding, he retracted the CC despite the fact that it actually turned out that there is a (non-zero) CC, the expanding universe notwithstanding. He got the right answer, but he abandoned it because he got it for the wrong reason.

Re: No, negative masses have not revolutionized cosmology

#49

Post by jessriedel »

jcranberry wrote: post #32
benwr wrote: post #2

This is a critical response to https://news.ycombinator.com/item?id=18609375 ; in the comments is a response by Jamie Farnes, the author of the paper, and a rebuttal by the blog's author.

I have absolutely no idea who is right, but I don't see why Dr. Hossenfelder is being so patronizing? In her rebuttal in the comments she says >Trust me, I do not enjoy doing this, but I do not want false claims to spread in the popular science literature. The only way to stop popular science lit from misinterpreting/aggrandizing scientific findings and publishing what eventually amounts to false claims would be to j…

> I don't see why Dr. Hossenfelder is being so patronizing

This is her personality. I don't think it's productive to resolving scientific disagreements and don't endorse it; she looks obnoxious in contrast to the author's polite reply in the comments. But it's definitely her natural state, and it seems to produce a writing style that readers enjoy.

> The only way to stop popular science lit from misinterpreting/aggrandizing scientific findings and publishing what eventually amounts to false claims would be to just never publish anything provocative at all

Hossenfelder is claiming much more than that the work is provocative. She's claiming it's highly disfavored for widely known reasons that the authors do not sufficiently address. She's probably also implicitly suggesting the authors are allowing their work to be marketed directly to the lay public, who do not have the expertise to assess the work, for personal gain. Obviously you can always give alternative explanations (the establishment is close-minded, or whatever), but keep in mind that Hossenfelder is waaaay outside the establishment.

Re: No, negative masses have not revolutionized cosmology

#50

Post by lisper »

JumpCrisscross wrote: post #42
apo wrote: post #36

Can't help but think of phlogiston: Eventually, quantitative experiments revealed problems, including the fact that some metals gained mass when they burned, even though they were supposed to have lost phlogiston. Some[who?] phlogiston proponents explained this by concluding that phlogiston had negative weight; https://en.wikipedia.org/wiki/Phlogiston_theory Eventually, the mass paradox was resolved by the realizatio…

Side note: it’s pretty incredible how phlogiston theory correctly linked burning and rusting, despite being unaware of oxidation. (Also, that plants have a part to play in the oxidation-carbon cycle.) I don’t know if oxygen theory would have developed without phlogiston theory first linking these phenomena.

Almost certainly. Joseph Priestly, the discoverer of oxygen, was a confirmed phlogistonist. He even called oxygen "de-phlogisticated air". The reason oxygen theory wasn't developed sooner was technological limitations, not intellectual ones: scientists simply didn't have any way of preparing pure oxygen to experiment on before Priestly.

(FYI, I just happen to know all this because I'm in the middle of preparing a series of lectures on the history of science, and I just finished the segment on the atomic theory. It's a really fascinating story.)

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