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The Reason We Haven’t Directly Detected Dark Matter

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

#101

Post by ddmd1 »

bensonn wrote: post #65
allcentury wrote: post #3

Really well written article, especially as someone who is interested in the topic but not an expert.

As I was walking the dog last night I was thinking about SEO and how even the "experts" don't really know Google's secret sauce or how the recipe will change. There are best-practices that seem to work but with Google's algo hidden and changing it seems funny to be an expert. But certainly they know more than their clients. That led my thoughts to dark matter. Expert: I am an expert on Dark Matter. Me: What is it? Ex…

I think the definition of "expert" can be pretty ambiguous. We have one type of "expert", the MLB hitter who is an expert because he is more skilled than others at hitting. And we have another type of "expert" who is an expert because she knows more about something than others. These are two very different types of "experts" but what makes them experts is their skill/knowledge relative to the general populance rather than skill/knowledge relative to some absolute.

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

#102

Post by krapp »

darawk wrote: post #98

Can someone that knows a bit more about this explain why we believe that this dark matter substance must exist and not simply that we have an incorrect model of gravitation?

The article describes the rationale, as does the "observational evidence" section of the Wikipedia article on dark matter[0].

tl;dr no alternative models for gravity can sufficiently explain all of the data, but general relativity and "dark matter being particles" does, so that's what we're going with.

[0]https://en.wikipedia.org/wiki/Dark_matter#Observational_evid...

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

#104

Post by sanxiyn »

foobarbecue wrote: post #78
sandworm101 wrote: post #76

Earlier quoted context omitted.

>> dark matter seems to repeatedly rub people the wrong way today, more so than any other scientific concept I can think of. Because, while interesting to a great many scientists, the practical implications of this knowledge are centuries away. Defining dark matter, understanding the backbone of our universe, isn't going to cure cancer. It isn't going to fix global warming. It isn't going to get us to Mars. So when p…

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.

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

#105

Post by gbrown »

tylerjwilk00 wrote: post #99
gbrown wrote: post #79

Earlier quoted context omitted.

I'm not a physicist, but my basic understanding of the state of the science tells me you're simply incorrect. We can observe the effect of dark matter via gravitational lensing, and folks much smarter than me have devised studies to exclude differential behavior of gravity at classical and galactic scales. Give me a recent and well supported study indicating that dark matter may be something other than matter, and I'…

This assumes that we are 100% certain that our understanding of gravitational lensing is accurate _AND_ that only mass affects gravitational lensing.

Nothing in science is assumed with 100% certainty. I would argue that working from our best available theories (while always looking for ways to falsify them) is perfectly reasonable.

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

#106

Post by acqq »

acqq wrote: post #34
beefield wrote: post #27

Earlier quoted context omitted.

But you do not need to measure it particle by particle. Just because those have mass, there should be a bunch of dark matter particles hanging around with earth. And given that we have quite good idea what earth consists of, there should be a discrepancy in some of the measurements that use earth's mass against the mass we have from our understanding of earth's composition. Unless, of course, the extra mass of earth…

Fascinatingly, it is known that the interaction of the dark matter with the Earth is so weak that there would be no "clumping" of it around the Earth at all! No "clumping" even around e.g. Sun can be observed. The "hanging around" is on the level of the whole galaxies, and sometimes the dark matter even remains outside of the whole galaxies, being too slow to follow their gravitational interaction(!) That's the famou…

Or more precise:

https://medium.com/starts-with-a-bang/ask-ethan-if-dark-matt...

There’s “just a little more” of the dark matter in our Solar system but way below the levels it could affect the measurements we can perform.

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

#107

Post by slacka »

Despite recent some initial evidence to the contrary,[1] I'm still a fan of the idea that dark mater is actually concentrations of matter/energy outside of our universe.

If string theory is true, gravity does leak into the multiverse, and we survive the Great Filter, then someday we may be able to use gravity to communicate universes outside of our own.

https://www.sciencenews.org/article/gravity-doesnt-leak-larg...

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

#109

Post by smallnamespace »

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.

Maybe not neutrinos specifically, but muon detectors are now being used for archaeology.

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

#110

Post by iandanforth »

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…

The article invites that kind of response by presenting arguments for the existence of dark matter as if they are undeniable. In reality the road to consensus was anything but smooth.

Science works best when you are skeptical of claims, test alternatives, and find evidence that contradict the alternative hypothesis. If you want to discuss controversial science you need to anticipate objections, show the work has been done to test the alternatives, and then leave the reader with the sense that your hypothesis is undeniable (because they can't think up any more objections.) This absurdly high burden is what makes science both hard and effective.

For dark matter a large number of the initial objections have been tested thoroughly, but since they weren't covered people unfamiliar with the subject (and I don't claim to be an expert) will naturally dredge up their own objections.

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