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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

#11

Post by duality »

"[T]he gravitational interaction is exchanged by a spin-2 field, whereas the electromagnetic force is exchanged by a spin-1 field. Note that for this to be the case, you do not need to speak about the messenger particle that is associated with the force if you quantize it (gravitons or photons). It’s simply a statement about the type of interaction, not about the quantization. Again, you don’t get to choose this behavior. Once you work with General Relativity, you are stuck with the spin-2 field and you conclude: like charges attract and unlike charges repel."

There was a bit of discussion about this on https://news.ycombinator.com/item?id=18609375 as well. Working through the exercise of how spin-2 mediated forces differ from spin-1 is a worthwhile exercise for those who are so inclined.

Re: No, negative masses have not revolutionized cosmology

#12

Post by khawkins »

Occam's razor is a heuristic used in the investigative process, not a principle. While it's fair to point out that a theory makes everything more complicated and thus might make it less likely to be sound, it's not fair to push back on the first bit of research into a theory because they haven't had the time to fully develop it.

Indeed, a scientific revolution generally starts by treating as false an assumption previously held as true. Not to say that this is a revolution, but if you push back too hard it won't be, whether it's true or not.

Re: No, negative masses have not revolutionized cosmology

#13

Post by onhn »

dpq wrote: post #10
onhn wrote: post #4

It is fun to read these things, and of course discussion is a good thing, but I do hope that blogs and comment sections do not end up serving any formal role in the scientific literature. There are several reasons for this: a blog's visibility is low compared to a preprint server (in the scientific community at least), the contents of the blog probably won't be as well-preserved, and there is a tendency to be more ca…

> I do hope that blogs and comment sections do not end up serving any formal role in the scientific literature. Why not? It all depends on the qualification of the people writing blog posts and comments. Remember that some 300 years ago a lot of scientific results existed in epistolary form only, and that first journals that looked like today's thing (like the Bulletin of the Royal Society) were basically compilation…

The continuation of the system you mention still exists today, and is the main channel of scientific discourse. I think it is a better channel to use when challenging someone's work.

(I don't agree with your statement that it depends on qualifications -- I don't think qualification is a measure of the importance of a contribution.)

Re: No, negative masses have not revolutionized cosmology

#14

Post by mbell »

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 interacts only through gravity (weakly) and must have a very specific and complex distribution in the universe to 'work'. That strikes me as neither 'simple' nor much different than tossing a constant into an equation to make it work. Similarly Dark Energy is an unknown form of energy that in uniformly distributed through the universe, which to me is just a fancy way of saying "we added a constant to make it work". In both cases I don't see how either are implicitly better than adding a 'creation term'.

Re: No, negative masses have not revolutionized cosmology

#15

Post by eutropia »

Tone of this blog post is extremely pedantic and comes across as if the author were personally insulted by the paper.

But her argument is basically "You didn't understand the math, and you misunderstood the work that you cited".

I feel like the burden is a little higher -- i.e. put in some effort to at least show the readers the math she's talking about and the counterfactual conclusions they arrive it if worked out.

I would be much more convinced if she took the original paper's claims at their strongest and most convincing and formulating a simple proof or mathematical argument why the paper is wrong -- instead it feels like she's knocking down a straw man and saying "you're too stupid to be doing this kind of work"...

Re: No, negative masses have not revolutionized cosmology

#17

Post by beezle »

onhn wrote: post #7
daveFNbuck wrote: post #5

Earlier quoted context omitted.

Why is that even a concern for you here? This is clearly written for laypeople.

It may be just text, but the points being made are technical, and the blog's author is an expert. The author of the paper is now in a position where they feel like they have to defend themselves publicly, and I don't think this is the forum for a scientific defense (for the three reasons I listed above).

If paper in question becomes fodder for the mainstream media (or at least the mainstream scientific media) then there is no reason why they should not have to defend their theory/arguments/speculations publicly in a less than formal peer reviewed forum, especially one of fairly high regard in that subject area.

Re: No, negative masses have not revolutionized cosmology

#18

Post by dplavery92 »

onhn wrote: post #7
daveFNbuck wrote: post #5

Earlier quoted context omitted.

Why is that even a concern for you here? This is clearly written for laypeople.

It may be just text, but the points being made are technical, and the blog's author is an expert. The author of the paper is now in a position where they feel like they have to defend themselves publicly, and I don't think this is the forum for a scientific defense (for the three reasons I listed above).

>The author of the paper is now in a position where they feel they have to defend themselves publicly

Due in large part to the fact that his paper was attached to a press release from Oxford--a point of contention for both Hossenfelder and Sean Carroll.

Re: No, negative masses have not revolutionized cosmology

#19

Post by garmaine »

khawkins wrote: post #12

Occam's razor is a heuristic used in the investigative process, not a principle. While it's fair to point out that a theory makes everything more complicated and thus might make it less likely to be sound, it's not fair to push back on the first bit of research into a theory because they haven't had the time to fully develop it. Indeed, a scientific revolution generally starts by treating as false an assumption previ…

Also that point seemed odd. Isn't unification of two previously separate phenomenon (dark matter and dark energy) simpler in Occam terms? It's using one thing to explain two, even if the actual mathematics are more complex to state. Also there's other troubling cosmological issues that this would appear to address, such as Hubble's constant having slight variation outside of measurement tolerance, which slightly differing fluid densities would explain (vs the current assumption of unknown sources of error).

Sabine's point, if it stands up, is that the author used a different equation of motion in their simulation than they write up in the paper. If true that's sloppy and bad, but it's not a point against the actual theory underlying the simulation, no?

Re: No, negative masses have not revolutionized cosmology

#20

Post by garmaine »

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…

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