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Researcher proposes model replacing dark energy/matter to explain universe
61–70 of 92 posts
Re: Researcher proposes model replacing dark energy/matter to explain universe
#62Earlier quoted context omitted.
> laws of nature "must" be shorter Coming at this from philosophy of science rather than as a physicist, I feel those quotes around "must". I think you also recognise how that might be a sort of "fundamentally wrong assumption". Imagine your words replayed 50 years in the future, not on physics but applied tp the problem of general AI/sentience. "The equations that we already have are sufficient to describe human tho…
It may be - probably is - a feature of the limits of our mental processes so far. But there's no good reason to assume the system itself just happens to mirror those limits. It would be very strange if the entire universe worked in inconsistent ways that matched the naive reasoning of some not very interesting animals on an ordinary star in the middle of nowhere.
We agree on human incompleteness. One limitation of recent
tree-dwellers on utterly unremarkable small blue-green planets on the
western spiral arm of the galaxy might be how we think about things
like "consistent"? Or "knowable"? What if those things weren't a
component of intelligence at all, but features a singularity which
looks different depending on which side you approach it from? In
maths, that's not even weird? [0]
Re: Researcher proposes model replacing dark energy/matter to explain universe
#63Earlier quoted context omitted.
The neutrino was also a particle that nobody could observe at the time when Pauli proposed it. It was just a manifestation of the energy and spin conservation. The Higgs is the same. It is not needed, but it solves the mass problem of the weak force. It is the only scalar field so far that we have observed and it was not clear whether it would exist at all. Quintessence and sterile neutrinos are also just pieces that…
"Measure first, discover later" can be a perfectly valid application of the scientific method. It's all about refining the resolution on reality. The problem with dark matter/energy is that we're not guaranteed to discover anything. It might just be wrong. The neutrinos and Higgs just happened to match their initial theory, so that's a survivorship bias. We can't just assume the same will play out for dark matter. It…
Or it might be at such high energies, that conventional particle accelerators will never observe it. Sterile neutrinos, axions and quintessence particles might have masses in the PeV range. We were lucky with the Higgs, and the W and Z Bosons, and the top quark.
Dark matter and dark energy might be a phenomenon in the GUT regime, which we will not observe with particle accelerators. We need more information about the Higgs, because it sticks out like a sore thumb of all the other particles. It is our first glimpse into the underlying fabric of the universe, as the Higgs field is non-zero everywhere and a scalar field. No other (known) particle behaves like that. But a future collider is expensive...
just my 2 cents
good plot for a scifi movie: aliens measure a different vacuum value of the Higgs field and discover sub-space communications ;-)
Re: Researcher proposes model replacing dark energy/matter to explain universe
#64Help me understand how can something so hard to detect exist in such vast quantity to change the rotation of galaxies.
Re: Researcher proposes model replacing dark energy/matter to explain universe
#65Earlier 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.
> never really understood how just adding extra invisible stuff to make the equations work is justified 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 That ‘unknown’ is dark matter. It’s a placeholder. It’s there and makes your total but you can’t explain it yet.
What if dark matter is actually 10 different items? Or you have rent and gas wrong, or rent and gas inexplicably depend on each other in some way?
Re: Researcher proposes model replacing dark energy/matter to explain universe
#66There seems to me to be a real cottage industry in proposing alternatives to Dark Matter and Dark Energy. I wonder why that might be. Why isn't there as much interest in alternatives to, say, Plate Tectonics or the Germ Theory?
There are- things like flat or hollow earth, antivax and HIV deniers, homeopaths etc. Proponents of all of the above are looking for a grand unifying cosmology. Dark matter and dark energy are confusing and unknown, so people want to just simplify them away. Flat earthers want to simplify away the existence of other planets. Antivaxers want to simplify away medicine. Because it's complicated astrophysics and largely…
"There are- things like flat or hollow earth, antivax and HIV deniers, homeopaths etc."
That's a fair point. It's just my perception that those things don't tend to be taken very seriously by people commenting on HN.
Re: Researcher proposes model replacing dark energy/matter to explain universe
#67Earlier quoted context omitted.
I am not a physicist, buy maybe the nature of dark matter and dark energy? What are their properties aside from their effect on the large scale structure of the universe?
FWIW (which is not much), I was an astrophysicist whose research was Dark Energy, though I arrogate to myself no authority on this topic as frankly a lot of knowledge I used to possess on the topic has been replaced by knowledge of tedious programming APIs (meh...it's a living). My sense was that, perhaps owning to their colorful (colorless?) names, and because they diffused into popular culture more than other equal…
correction: "OWING to their colorful...names" not "owning to their colorful...names"
Re: Researcher proposes model replacing dark energy/matter to explain universe
#68Earlier quoted context omitted.
I am not a physicist, buy maybe the nature of dark matter and dark energy? What are their properties aside from their effect on the large scale structure of the universe?
FWIW (which is not much), I was an astrophysicist whose research was Dark Energy, though I arrogate to myself no authority on this topic as frankly a lot of knowledge I used to possess on the topic has been replaced by knowledge of tedious programming APIs (meh...it's a living). My sense was that, perhaps owning to their colorful (colorless?) names, and because they diffused into popular culture more than other equal…
There is an alternate timeline where dark matter receives an extremely boring name like "inferred low luminosity particulate" and 100,000 very repetitive internet conversations never happen.
Re: Researcher proposes model replacing dark energy/matter to explain universe
#69Earlier quoted context omitted.
QM and GR are mutually exclusive: if one is right, the other must be wrong (of course, it's very much still possible that both are wrong). If you use GR to predict the movement and interactions of photons in a medium, it's just wrong. If you use QM to predict the movement of light around a huge body, especially a black hole, it's just wrong. And what's worse, there is no limit or term you can add such that you could…
Well, actually we have developed a very good feeling when to apply which theory. From subatomic particles to the large scale structure of the universe the right theories applied give us excellent results. lambda CDM models very well fit to the observed structures and the standard model describes all the particles that have been observed so far. We are desparately looking for effects that are unexplained by the standa…
Sure, we have a feeling for when to use one and when the other, but a feeling is not a physical theory. Also, the Lambda CDM literally doesn't explain what 95% of the universe is made of and how it behaves, it simply posits that it exists. So even if the Lambda CDM is perfectly correct, it's still extremely far from a complete model.
Not to mention, the reason the tension between GR and QM is not very prominent is that we don't know how to conduct "medium scale" experiments, even though the vast majority of physical objects on Earth are in this medium scale: far too big to count particles, too small to measure observe gravitational bending effects. Basically, both QM and GR are completely useless for telling you what happens in compel scenarios like two billiards balls colliding on a frictionless table. They both have equations that are far too complex to actually solve for anything like this. And QM is even worse - even if you could solve the equation, it doesn't tell you what the balls will do, it only tells what chance they have atof being at some position with some velocity and spin if you were to measure that, whatever "measurement" might mean.
Re: Researcher proposes model replacing dark energy/matter to explain universe
#70If you ask me, Inflation is far more problematic than the Dark Stuff. Nevertheless, so far it remains the best explanation we have for observed phenomena ¯\_(ツ)_/¯
What does inflation explain though? It was proposed as an explanation for CMB spectrum. Anything else?
Rapid expansion of the early Universe. We need to have Inflation in order for the Big Bang to work as a theory.
Without it, the Big Bang theory runs into major problems:
1. The Horizon Problem: The cosmic microwave background (CMB) has nearly identical temperature in all directions, suggesting the entire observable universe was once in contact. But without inflation, opposite sides of our universe would never have been able to “communicate” and reach this equilibrium.
2. The Flatness Problem: Our universe is remarkably “flat” (parallel lines stay parallel), which would require impossibly precise initial conditions without inflation.
3. The Origin of Structure: Inflation explains how quantum fluctuations during this expansion became the seeds for galaxies and cosmic structures we see today.