31–40 of 92 posts
> The origin of these temporal singularities is unknown—safe to say that the same is true of the moment of the Big Bang itself If you still want to assume that weird things you mathematically need happen whenever you need them for no reason then why not stick with cosmic inflation?
I don't have access to the paper, but it seems to make zero testable predictions and is therefore just mathematical fiction. If it's not falsifiable, it's not science. EDIT: the last sentence is "Given sufficient redshift (or, equivalently, time) resolution effected by the redshift slicing, one might just find that the Hubble diagram exhibits jumps in the redshift distance relation, which would be very revealing." So…
If a theory doesn’t generate at least one falsifiable prediction it’s not a scientific theory.
Earlier quoted context omitted.
That paper focuses on rotation curves, like all DM skeptics. I can only assume because this problem is understandable with high school level math. But that's neither the only nor the best evidence for DM. If your new hypothesis doesn't even mention the CMB power spectrum, it's not really worth listening, sorry. And to be taken seriously, it has to explain at least most of the data. DM does that, everything else does…
The phrase "Dark Matter" literally means we don't know and therefore until something testable is postulated and tested (to be fair i believe some candidates have fallen by the wayside over the years as measurement has improved), it's principally equivalent to plugging in a giant X and giving it properties not unlike Fermi's famous elephant curve fitting comment.
Basically, our equation isn't working, and roughly speaking the equation has gravity on the left hand side and matter content on the right hand side. Matter tells spacetime how to curve and spacetime tells matter how to move, is the old motto. Because the equation isn't working, we have two options: modifying the left hand side or modifying the right hand side (or both). In my perception, researchers refer to the first option as theories of modified gravity, and the other option as theories of dark matter.
Putting both options into one category is over simplifying the situation and isn't helpful.
I don't have access to the paper, but it seems to make zero testable predictions and is therefore just mathematical fiction. If it's not falsifiable, it's not science. EDIT: the last sentence is "Given sufficient redshift (or, equivalently, time) resolution effected by the redshift slicing, one might just find that the Hubble diagram exhibits jumps in the redshift distance relation, which would be very revealing." So…
I’ve never really understood how just adding extra invisible stuff to make the equations work is justified either? It seems more likely there is simply something wrong with the equations.
IANAP but here’s my understanding.
At the end of the month you spent $2000, you’re not sure how so you track down your expenses:
- rent $500
- groceries $120
- gas $80
- …
- unknown: $123
Earlier quoted context omitted.
Nobody said it's "true", whatever that even means for a model. The claim is that it's the best anyone has been able to come up with. And not for a lack of trying. Everybody also acknowledges that there are issue with DM, it's just that every other known model has bigger issues.
Ha, my bad When you write "this is the [..] most common objection laypeople have", I understood "In contrast with the experts who know better" Of course, if as you say, everybody knows that this is a wrong, specifying "laypeople" seems unnecessary
I don't have access to the paper, but it seems to make zero testable predictions and is therefore just mathematical fiction. If it's not falsifiable, it's not science. EDIT: the last sentence is "Given sufficient redshift (or, equivalently, time) resolution effected by the redshift slicing, one might just find that the Hubble diagram exhibits jumps in the redshift distance relation, which would be very revealing." So…
https://arxiv.org/abs/2503.08733
> it seems to make zero testable predictions and is therefore just mathematical fiction
I'll have a look when I get the time, but the reference to his previous paper really doesn't bode well.
Earlier quoted context omitted.
This is basically the first and most common objection laypeople have. (In fact, this comes up in every single thread on HN about DM, not exaggerating.) Believe it or not, scientists have thought of that as well. They tried, and nothing fits the data as well as the standard model. The trope is so common that there even is an xkcd for it: https://www.xkcd.com/1758/
A common objection, and for good reason: just because you do not know the right model does not make your bad model somehow true I mean, when you miss 85% of the stuff, you gotta admit that, perhaps, your stuff is wrong And yes, it can work even if it is wrong
Earlier quoted context omitted.
It doesn't, and the problems have only become more problematic over time, but it's the least bad hypothesis that's broadly accepted. I suspect a generational succession is required for new paradigms to be contemplated. There are many researchers proposing simpler, novel, and testable solutions that seem to go unnoticed. For example, I'm a fan of Alexandre Deur's work. He has some simple and elegant solutions that I'v…
That paper focuses on rotation curves, like all DM skeptics. I can only assume because this problem is understandable with high school level math. But that's neither the only nor the best evidence for DM. If your new hypothesis doesn't even mention the CMB power spectrum, it's not really worth listening, sorry. And to be taken seriously, it has to explain at least most of the data. DM does that, everything else does…
I know his work has been contentious in the past, and that his past work has used multiple models that are not entirely compatible for different problems, weakening his claims.
That said, at least from my armchair it seems like a worthwhile direction to pursue.
Earlier quoted context omitted.
I’ve never really understood how just adding extra invisible stuff to make the equations work is justified either? It seems more likely there is simply something wrong with the equations.
Well, the point is actually pretty simple. You start with an equation that works for some galaxies. Then you find a galaxy where it doesn't work - you adjust the equation and now it works again. But then you find a new galaxy where it still doesn't work, you adjust again. You try this for 5, 10, 20 galaxies, just adjust the equation - but at some point there is a limit where the equation doesn't bare any more adjustm…
Dark matter is not Fermi's elephant, as invoked elsewhere in the thread. It's more like the story of the blind men and the elephant - except that the blind men recognise that their individual observations, taken together, admit a coherent explanation.
Earlier quoted context omitted.
The phrase "Dark Matter" literally means we don't know and therefore until something testable is postulated and tested (to be fair i believe some candidates have fallen by the wayside over the years as measurement has improved), it's principally equivalent to plugging in a giant X and giving it properties not unlike Fermi's famous elephant curve fitting comment.
Just FYI I have a PhD in cosmology, so no need to explain to me what "Dark Matter" does or doesn't mean, but thanks anyway. It sounds like you saw that video by Angela Collier about how Dark Matter is a set of observations, and while I think it's a good video, it's a bit disingenuous to pretend that working scientists put theories of dark matter and theories of modified gravity in the same category. I know Collier li…