Scientists say they have found evidence of an unknown planet in our solar system
independent.co.uk
independent.co.uk
Here is a previous talk where he goes to great lengths to explain and visualize the Planet 9 hypothesis.
The article also notes that this claim is being made by the same scientist that popularized the idea of a planet 9.
There is plenty of room for doubting this specific planet 9 claim without changing any laws of physics.
For sure!
Emphasizing that we haven't explicitly discovered what dark matter actually consists of inevitably leads to people who don't understand the evidence dismissing it as "made up" and instead pushing explanations that have a much higher burden of proof (eg modified gravity or modified light speed, which struggle on the point that there are structures which have more or less "extra mass" than usual).
"We know the facts. We have it all figured out." Then the facts change years later.
Or "There's a great mystery here, a secret we haven't yet found. We're still looking, but here's some ideas that seem to explain 90% of what we're seeing."
The second is so much more engaging and would promote more interest and science funding.
The average person consumes science from news, not from scientists.
A lot of news outlets and "science communicators" have been repeatedly dumbing down scientific subjects for non-scientific purposes. Clickbait, ideology, lazyness.
The nature of dark matter should be presented to the public as it is. If we dumb it down too much, it's the same as not presenting it at all, or misrepresenting it.
So presenting things as is doesn't really work because people still have only partial information relative to those who work in the field. Thus being the same in effect as misrepresentation.
I think I was too harsh in saying that it should be presented as absolute fact, ideally I'd rather the average person be much better educated in their understanding of the scientific process, such that they'd have enough humility to recognize that watching a documentary does not give them all the facts. But that doesn't seem realistic, so it's a difficult issue.
Yes! However, I don't know how realistic this is.
Stuff like baryon acoustic oscillations are interesting enough on their own
To me, that seems far fetched. Would it not be more likely that our formula for large distance gravity interactions should change?
Further, while that was the observation dark matter was originally introduced to explain, there are a lot of other observations it has since explained. For example we can see regions of space with high gravity that do not appear to have any substantial amounts of regular matter in them. Again, stuff we can't directly detect as it doesn't interact with light but still has mass is a really simple explanation.
And from a theoretical perspective, there's no reason to think dark matter is weird. There is no law that says all particles need to interact with the electromagnetic force, indeed we know of many particles that don't even though none of the ones we know are particularly good candidates for dark matter. That there is a particle we don't know about specifically because it's most important property is that it is hard for our instruments to directly detect is far more likely than that one of our most successful theories which has an extremely firm foundation and has correctly predicted numerous observed phenomena with incredible accuracy has been wrong this whole time.
What I don't like about this, is that we take the observations, apply some custom guesses as to why the spacetime is folded differently and... there you go, your formulas now match. It smells too much like the explanation of geocentric system, where they invented that planets also circle around a perceived dot on their trajectory path and that happily coincides with the Earth's rotation.
I think what we are missing is that these behaviors need to be predictable. We don't know where these anomalies in spacetime curvature will be and why they are there. And as I stated in another comment here, I think dark matter is a bad name for the unexplained spacetime curvatures (warpings?, wrinkles?).
> I think what we are missing is that these behaviors need to be predictable. We don't know where these anomalies in spacetime curvature will be and why they are there.
But we do! We can see galaxies that have been stripped of their dark matter and we can find nearby the dark matter that was stripped. We can predict, based on our theory of dark matter where these gravitational anomalies will be, then we look there and lo and behold we see them. We aren't applying custom guesses to match our observation, the universe just happens to match exactly what we'd expect it to look like if it contained a bunch of matter that didn't interact with the electromagnetic force.
> I think dark matter is a bad name for the unexplained spacetime curvatures (warpings?, wrinkles?).
Dark matter isn't the space time curves, which aren't particularly special. All massive particles produce such warping, and we just call it gravity. Dark matter is matter (stuff that interacts with gravity) which is dark (does not interact with light). We would expect it, assuming it exists, to produce such warping of spacetime, which again is exactly what we see.
It is like a boy calculating physics homework, only to be 30% off, so he will add some constant to get to result he wants. It sounds ridiculous, does it? Well dark matter/energy is that constant to get result we expect.
Yes, and then implications of the invention are followed up on and dark matter has passed a lot of tests and has strong explanatory power (i.e. parsimony, Occam's Razor) over a variety of phenomena, from small dark galaxies up to the matter web structure of the observable universe.
So it has very very strong evidence behind it, at this point. With an unbroken trend of accumulated evidence.
The reason for remaining questions stem from the fact that the small scale nature of dark matter is not yet characterized. Which differs from all other gravitationally active materials we know of - i.e. all the particles in the standard model.
But we don't know the fine structure of space either, and we don't count that against General Relativity. In both cases the large scale properties of each phenomena, that we can measure and model, provides clear reasons why investigating the small scale properties has been challenging.
In both cases, it is the extreme weakness of gravity at small scales, and the low, if any, alternative interactions with the standard model particles we know well.
For example, the dark matter might be mass gathering of otherwise non reactionary particles like neutrons, it could be wrinkles in spacetime that have a similar effect as massive normal matter bodies have, or they could be advanced civilizations that learned how to hide their star systems from the rest of the universe.
We simply don't know. I suppose we had to name it somehow, but the name just sounds wrong. It might not be matter at all. It is also not dark, it's non-reactive.
Why did they not rather choose something like spacetime wrinkles?
The two word choices can be quibbled with, but they form an accurate shorthand for what we know.
If the fine structure is discovered to be wrinkles in space I expect there will be a renaming during a time of great celebration by the future Nobel Prize winners! Especially if that also shone light on space-time's ultimate structure!
Edit: I will humbly propose a name for your postulated tiny space wrinkles: Wrinky-dinks!
https://www.youtube.com/watch?v=PbmJkMhmrVI&t=15s&pp=ygUaZGF...
https://en.wikipedia.org/wiki/Discovery_of_Neptune
- "The planet Neptune was mathematically predicted before it was directly observed. With a prediction by Urbain Le Verrier, telescopic observations confirming the existence of a major planet were made on the night of September 23–24, 1846,[1] at the Berlin Observatory, by astronomer Johann Gottfried Galle (assisted by Heinrich Louis d'Arrest), working from Le Verrier's calculations. It was a sensational moment of 19th-century science, and dramatic confirmation of Newtonian gravitational theory. In François Arago's apt phrase, Le Verrier had discovered a planet "with the point of his pen"."
They are only half way there (afaik, but I could have misunderstood their point)
Also it's predicted that a star comes with 1,500 AU of the sun every billion years or so, a star could have thrown things out of whack and left.
But if you suspect it’s a planet, you know it’s in orbit around the sun. Feels like something we can track.
Our planets' orbit do tend to be somehow aligned, so you could make the (possibly wrong) assumption that the 9th planet is also somehow aligned. This might reduce the search space by 50%+.... but even then you'd still be several orders of magnitude off by the precision needed to go looking for it.
Space is big.