The Reason We Haven’t Directly Detected Dark Matter • Hacker News Board

Re: The Reason We Haven’t Directly Detected Dark Matter

#141

Post by tokyodude » Sat, Oct 13, 2018, 4:35 PM UTC

krapp wrote: post #56

I like how we have an article explaining the rationale behind dark matter and the scientific principles that lead to the conclusion that it exists, but most of the threads here are simple declarations that no, they must all simply be wrong or not considering some simple alternative. Can people maybe, just maybe not assume that scientists are idiots or, as once dead commenter puts it, charlatans? If you disagree with…

Because in one sense it sounds as bad as alchemist (who were once considered scientists).

We're riding on the back on a turtle

We're the center of the universe

All things are made from earth, air, water, fire

Space is filled with ether

Dark Matter "feels" like it's going to be yet another of those things that will be added to the list of things scientists used to believe.

I fully acknowledge they aren't stupid and that I am not remotely knowledgeable about any of it but go read the transcript from this Nova episode about actual scientists predictions about what we'd find on Venus

http://www.pbs.org/wgbh/nova/transcripts/2210venus.html

The scientists in 1995 we're not stupid either but their predictions certainly sound stupid in 2018.

https://www.scientificamerican.com/article/is-dark-matter-re...

Re: The Reason We Haven’t Directly Detected Dark Matter

#142

Post by [deleted] » Sat, Oct 13, 2018, 4:38 PM UTC

tokyodude wrote: post #141

krapp wrote: post #56

I like how we have an article explaining the rationale behind dark matter and the scientific principles that lead to the conclusion that it exists, but most of the threads here are simple declarations that no, they must all simply be wrong or not considering some simple alternative. Can people maybe, just maybe not assume that scientists are idiots or, as once dead commenter puts it, charlatans? If you disagree with…

Because in one sense it sounds as bad as alchemist (who were once considered scientists). We're riding on the back on a turtle We're the center of the universe All things are made from earth, air, water, fire Space is filled with ether Dark Matter "feels" like it's going to be yet another of those things that will be added to the list of things scientists used to believe. I fully acknowledge they aren't stupid and th…

[deleted]

Re: The Reason We Haven’t Directly Detected Dark Matter

#143

Post by EamonnMR » Sat, Oct 13, 2018, 4:44 PM UTC

beefield wrote: post #16

perlgeek wrote: post #11

My attempt to summarize the reasons would be: We haven't directly detected dark matter because we don't really know what we are looking for, and there are only a few things we can search for. Dark matter might not be structured in a way we can investigate with current technology. Also, dark matter doesn't interact much with regular matter, which makes the search even harder.

> Also, dark matter doesn't interact much with regular matter, which makes the search even harder. This is (one of the many places) where I get lost. It has mass, so it by definition interacts with anything with mass? Are these particles supposed to be so small and so rare that they can't be measured even at the scale of solar system? (How much dark matter would be in the solar system? What would be the average densi…

You need to think about what types of interactions we normally perceive-they're all dependant on the electromagnetic force. DM does not appear to absorb or emit light, so it stands to reason that it also won't repel electromagnetically (ie touch things.)

Re: The Reason We Haven’t Directly Detected Dark Matter

#144

Post by dwaltrip » Sat, Oct 13, 2018, 4:45 PM UTC

sanxiyn wrote: post #104

foobarbecue wrote: post #78

Earlier quoted context omitted.

How do you know it won't cure cancer? Marie Curie checked out some invisible physics and discovered radioactivity. Now we use it to treat cancer. I suspect that practical outcomes and technologies arising from understanding dark matter will be huge. Also, I think you're missing the point of astronomy. "astronomers" today are generally astrophysicists or planetary scientists, and they are studying fundamental, mostly…

> I suspect that practical outcomes and technologies arising from understanding dark matter will be huge. I doubt it. More than 50 years after discovery of neutrinos, we are yet to find any practical outcomes or technologies.

The neutrino is part of the standard model. The dark matter may easily be entirely new physics, outside of the standard model. The implications may be enormous.

Moreover, even if the dark matter itself doesn't itself lead directly to to new tech, it is very likely that subsequent discoveries will.

Re: The Reason We Haven’t Directly Detected Dark Matter

#145

Post by EamonnMR » Sat, Oct 13, 2018, 4:49 PM UTC

chongli wrote: post #72

tomp wrote: post #54

The simplest “proof” of dark matter - Kepler’s Laws dictate that objects with smaller orbits (closer to center) move faster (in terms o fangular velocity). Our solar system works like that. Our galaxy doesn’t - its spiral shape indicates that the angular velocity varies minimally with radius.

This carries the implicit assumption that all forces fall off monotonically with distance. Maybe gravity doesn't? Maybe it has a curve similar to a meteor impact crater: raised in the middle, a deep valley, and raised at the outer edge? Of course, with more evidence, such as the observations of the Bullet cluster, these simple explanations fall apart. But at any rate, it's not enough to take one observation and assum…

Inverse square makes sense because you can model it as a finite number of particles with decreasing density as they move away from the source, like shotgun pellets. MND is like if more pellets just sort of appeared out of thin air at a certain distance... It would open up all sorts of different questions, starting with: how do those particles know when and where to spawn more particles? Where does the energy come from (or where does it hide until it decays out in the form of more gravitons?)

Re: The Reason We Haven’t Directly Detected Dark Matter

#146

Post by TangoTrotFox » Sat, Oct 13, 2018, 4:49 PM UTC

jccalhoun wrote: post #126

gmjoe wrote: post #63

Earlier quoted context omitted.

Agreed 100%. Indeed, this is one of the best articles I've come across which covers several of the reasons we believe dark matter exists, as opposed to us just needing to modify the theory of gravity. For whatever reason, dark matter seems to repeatedly rub people the wrong way today, more so than any other scientific concept I can think of. I actually wonder if it's something psychological -- if the universe is only…

>For whatever reason, dark matter seems to repeatedly rub people the wrong way today, more so than any other scientific concept I can think of. I think that it is because it is so hard to understand. You can't see it or touch it but it is supposed to make up the majority of mater in the universe. So what is it then? For a lot of people that's a hard thing to get and it would be easier if the answer was something we u…

Consider something. What is it that makes god did [x] an improbable hypothesis? The fundamental reason is that there is no direct evidence of said god. There is indirect evidence and logical arguments that can favor a god, but that means nothing when you cannot observe a god, you cannot measure a god, and there is no direct evidence for that god.

Dark matter still holds more in common with the divine than the practical, for now. We've developed and carried out a slew of extremely clever experiments to try to affirm its existence, yet each and every experiment has returned a resounding negative. This is one of the biggest problems with the gulf between experimental and theoretical physics that's been rapidly expanding over the past several decades.

Re: The Reason We Haven’t Directly Detected Dark Matter

#147

Post by Pica_soO » Sat, Oct 13, 2018, 4:52 PM UTC

gmjoe wrote: post #63

krapp wrote: post #56

I like how we have an article explaining the rationale behind dark matter and the scientific principles that lead to the conclusion that it exists, but most of the threads here are simple declarations that no, they must all simply be wrong or not considering some simple alternative. Can people maybe, just maybe not assume that scientists are idiots or, as once dead commenter puts it, charlatans? If you disagree with…

Agreed 100%. Indeed, this is one of the best articles I've come across which covers several of the reasons we believe dark matter exists, as opposed to us just needing to modify the theory of gravity. For whatever reason, dark matter seems to repeatedly rub people the wrong way today, more so than any other scientific concept I can think of. I actually wonder if it's something psychological -- if the universe is only…

For me its the similarity to another pre-relativistic concept- the invisible ether between the worlds- that rubs me the wrong way.

And its tough to imagine the consequences of something you are absolutely not able to detect, you could be flying towards with 250 km/s. Its kind of scary- imagine you hit something like that and it causes earth quakes or a shake up of the solar system. Just think if that missing gas giant was actually a Blob of DM cycling the solar system.

And, well - the situation seems similar to this over focused on the problem situations you sometimes have in coding. Everyone has committed to a very narrowed down problem solution, that is just not working out, but instead of stepping back, a thousand angles are tried to solve the problem in the narrow scope.

Many here, just want to help. Which, given the Enlightenment as a project of everyone capable, against a Elite fighting for dogmatic ignorance - is a good thing in my book.

The article is missing in my opinion a confidence rating for every observation- how often this has been tested in experiments or observed in space. Otherwise it was good.

Re: The Reason We Haven’t Directly Detected Dark Matter

#148

Post by dwaltrip » Sat, Oct 13, 2018, 4:54 PM UTC

lottin wrote: post #38

So, basically physicists have deduced two facts, and these facts don't agree with one another. From this they conclude that there must be something else in the universe, something unseen and undetectable, that they call dark matter. But what about the other possibility, which seems far more reasonable to me, that either one of the facts is wrong?

Is it possible that you haven't had the training to understand the weight of the evidence and theory that led to this conclusion? Perhaps some humility is necessary here?

Re: The Reason We Haven’t Directly Detected Dark Matter

#149

Post by _kccq » Sat, Oct 13, 2018, 4:56 PM UTC

jumpywizard wrote: post #77

Anyone trying to use machine learning to make a "black box" mathematical framework? Feeding known measurements as "learning" (including known anomalies and discrepancies)? Using techniques such as deep learning for program synthesis. https://www.microsoft.com/en-us/research/blog/deep-learning-...

Yep, it's been done before by Cornell researchers, in 2009. You provide a bunch of data to a program and it hums for awhile and derives some equations from the observation. In the story written around the time, it took positions of a pendulum swing and derived laws of motion from it. See https://www.wired.com/2009/04/newtonai/ (and lots of other articles around the time.)

You could feed a spreadsheet into and then it would iterate for awhile, converging toward most accurate equations describing the system. Or in my case, diverging from what I was sure was the solution. It was a hit and miss with most data (honestly, an eyeball and a few braincells did better with some data sets), but all the same I used it to lazily approximate position equations for some programs I was writing.

The desktop program was called Eureqa which then got ported to the cloud for obvious capacity increases, and relabeled into a company/product called Nutonian. Most recently bought by "DataRobot" and it's now being sold for sales optimizations. Because science.

Re: The Reason We Haven’t Directly Detected Dark Matter

#150

Post by kurthr » Sat, Oct 13, 2018, 5:00 PM UTC

gmjoe wrote: post #63

krapp wrote: post #56

I like how we have an article explaining the rationale behind dark matter and the scientific principles that lead to the conclusion that it exists, but most of the threads here are simple declarations that no, they must all simply be wrong or not considering some simple alternative. Can people maybe, just maybe not assume that scientists are idiots or, as once dead commenter puts it, charlatans? If you disagree with…

Agreed 100%. Indeed, this is one of the best articles I've come across which covers several of the reasons we believe dark matter exists, as opposed to us just needing to modify the theory of gravity. For whatever reason, dark matter seems to repeatedly rub people the wrong way today, more so than any other scientific concept I can think of. I actually wonder if it's something psychological -- if the universe is only…

It's really difficult to have something useful or interesting to say as a layperson about dark matter (or most science fields) so people rely on tropes.

Special and General Relativity - "it's all relative man" Quantum Mechanics- "spooky action at a distance" Dark Matter - "if you can't see it, maybe it's just not there" Flat Earth - "you can't prove it's round"

There are more complex versions of this like the interesting, but debunked Tao of Physics and various cranks with new theories of everything (or perpetual motion), but they aren't accessible or interesting to the masses because they don't fit a convenient narrative.

Most big science and engineering takes a lot of work, understanding, and time to be accepted or have a big impact, but we're always looking for the new News.