General science thread

January 15th, 2018 at 8:13:30 AM permalink
Nareed
Member since: Oct 24, 2012
Threads: 345
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To paraphrase Prof. Farnsworth: Good news, everyone! Theoretical physics is hopelessly stuck!

Thus far theoretical physics has been unable to come up with a unified theory (a means to link the four fundamental forces in the universe: gravity, the strong nuclear force, the weak nuclear force, and the electromagnetic force), an explanation for the mass of the Higgs boson, a quantum explanation for gravity, an explanation for dark matter and dark energy, among other things. Promising theories like Supersymmetry, String Theory, etc. remain unconfirmed by experiment and observation.

This has happened before.

Near the end of the XIX Century, physics also had a lot of questions it couldn't find answers to, and theories it couldn't find experimental support for. eventually answers came in the form of Quantum theory, Atomic theory, Special Relativity, General Relativity, and the Standard Model of subatomic particles. Most of this contained aspects which were completely unexpected, Quantum theory in particular.

Beyond advancing knowledge of physics, many of these had practical applications that went on to revolutionize the world. Quantum physics is an essential part of modern electronics, for instance, and Atomic theory enabled things like nuclear bombs and nuclear reactors. The GPS in your phone wouldn't be accurate at all without the needed corrections imposed by both Special and General Relativity.

So why is it "Good News!"

Physicists tend to try to explain the universe based on what they know. This is only natural, of course. When this fails, though, it means there's something they don't know out there, waiting to be discovered. The new knowledge, when it comes, tends to be revolutionary, and often to open doors to technologies we couldn't even imagine before.
Fresh out of clues. Did you really expect anything?
January 22nd, 2018 at 3:45:30 PM permalink
Nareed
Member since: Oct 24, 2012
Threads: 345
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Maybe the Earth is awash in dark matter.

Neutrons are very stable inside an atomic nucleus. They make up about half the mass of regular matter (give or take), and help keep atomic nuclei whole.

Outside a nucleus it's a different story. Solo neutrons decay rather rapidly into protons, with a half-life of, well, therein lies the possible dark matter.

There are two methods for measuring the half-life of neutrons. 1) The bottle method. Here you keep neutrons at a very low temperature (so they'll stay put) in a container, and then count how many are left after a given time. 2) The ray method. You shoot a ray of neutrons and count how many protons come out the other end.

The methods give differing answers (by about 8 seconds, if memory serves). This may be an operational matter involving the limitations of both methods. Or it could mean some neutrons decay into something other than protons. Method 2, the ray method, counts protons only. If neutrons decay into, say, a type of dark matter particle, they wouldn't be counted or even detected. Method 1, the bottle, counts how many neutrons are left, not what particle they decay into.

So there's a hypothesis that some neutrons decay into dark matter particles (plus other subatomic detritus; subatomic decay is a complex mess involving laws of conservation and massless, chargeless particles).

Testing the hypothesis will be hard, if the resulting neutron decay particle cannot be found, identified and measured. The hope is that dark matter particles are WIMPs, that is Weakly Interacting Massive Particles. I don't know whether there is a clever acronym for Non-Interactive Massive Particles (NIMPS? That's not clever at all), but if that's what the neutrons decay into, then there is, by definition, no currently available means of detecting or identifying them, much less measuring them.

Well, no direct means.

Say you place a known mass of neutrons in a bottle and cool them down as per method 1. You also know the mass of the bottle and all other stuff. good. Let the neutrons decay. Next remove all neutrons and protons. You know their masses as well. Count the detritus that spews out (neutrinos, photons, whatever), also of known mass. If any mass remains, then it is the dark matter particle.

Even if you can't detect and identify it, you'll know it exists and what it's mass is.

Of course, it's nowhere nearly as simple as I make it sound. nor as cheap. i suspect by "cooling down" the neutrons, we're talking at or near absolute zero, -273 C. That's liquid helium territory.

This doesn't solve the whole of the dark matter puzzle, unless there was an EFFING BIG load of unattached neutrons shortly after the Big bang, and most of them decayed into this NIMP type.
Fresh out of clues. Did you really expect anything?
January 22nd, 2018 at 5:25:44 PM permalink
odiousgambit
Member since: Oct 28, 2012
Threads: 89
Posts: 2205
You can keep neutrons in a test tube or something? I can only picture them being in a nucleus or being ejected at high velocity . Shows you what I know.
Mustard:You like Kipling, Miss Scarlet? Sure, I'll eat anything [from movie]
February 4th, 2018 at 7:44:16 AM permalink
odiousgambit
Member since: Oct 28, 2012
Threads: 89
Posts: 2205
Mount Agung in Indonesia is said to be likely to effect world climate [making a cooler climate] if it just keeps on erupting like it has been since November. Or it could even develop into something with more impact .

Slide show:

https://www.express.co.uk/pictures/pics/15749/Bali-volcano-update-live-Mount-Agung-eruption-latest-news-updates-pictures
Mustard:You like Kipling, Miss Scarlet? Sure, I'll eat anything [from movie]
February 4th, 2018 at 10:24:01 AM permalink
Fleastiff
Member since: Oct 27, 2012
Threads: 54
Posts: 5888
Quote: odiousgambit
Mount Agung in Indonesia is said to be likely to effect world climate
likely to affect world climate?
All dust particularly in the upper atmosphere will have a cooling effect.
February 4th, 2018 at 11:07:57 AM permalink
odiousgambit
Member since: Oct 28, 2012
Threads: 89
Posts: 2205
Quote: Fleastiff
likely to affect world climate?
All dust particularly in the upper atmosphere will have a cooling effect.


affect, effect, I can't effing remember
Mustard:You like Kipling, Miss Scarlet? Sure, I'll eat anything [from movie]
February 4th, 2018 at 12:59:15 PM permalink
ChesterDog
Member since: Oct 24, 2012
Threads: 0
Posts: 30
Quote: odiousgambit
Mount Agung in Indonesia is said to be likely to effect world climate [making a cooler climate] if it just keeps on erupting like it has been since November. Or it could even develop into something with more impact .

Slide show:

https://www.express.co.uk/pictures/pics/15749/Bali-volcano-update-live-Mount-Agung-eruption-latest-news-updates-pictures


Find the connection between this Rocky and Bullwinkle character and the effects of a South American volcano.

See this Russian famine article.
February 4th, 2018 at 1:22:41 PM permalink
Fleastiff
Member since: Oct 27, 2012
Threads: 54
Posts: 5888
Interesting famine article.

Perhaps my post from the WOV site would be relevant to such a Winter:
"I do hope you will be able to make it to Spring Fling but if you will be staying a few nights in Copenhagen, their largest hostel will be serving some special breakfasts in addition to their full English and Continental breakfasts: muffins with apple, apricot and almonds made using flour ground out of worms; baked wax moth larvae with paprika; and grasshoppers prepared with lime."
Or
Perhaps we could all do that $187.00 Ikea mealworm bin set up that somebody emailed me about recently.
Or
Perhaps that use ants to make beer and then use the beer to ferment quail eggs that was considered a tad too extreme in an earlier blog post.

My point is that today a Volcanic Winter would be a major event but it would not have quite the consequences we think it would. People would not die but their diets might under go a radical change and indoor microgreen systems would flourish as would Controlled Environment Agriculture set-ups.
February 14th, 2018 at 2:58:01 PM permalink
Nareed
Member since: Oct 24, 2012
Threads: 345
Posts: 12529
About the neutron possibly decaying into a dark matter particle, I dug up Gamow's book about Mr. Tompkins, and re-read the chapter on the nucleus. This is a charmingly illustrated, rather tranquil, setting involving a wood carver who builds nuclei using "quantum oak."

The wood carver uses paint to mark electric charges on his quantum wood particles. Positive charge is red, negative is green. If you paint a symmetrical object, like a ball, half red and half green, and spin it fast enough, it will appear white. Anyway, when he leaves a white (neutral) neutron alone, it turns red and a small amount of green paint gets ejected. This is the neutron decaying into a proton and emitting an electron.

Next when white neutrons are placed in a nucleus with red (positive) protons, the whole mass turns pink. The wood carver explains each particle tries to get the positive charge, but can't hang on to it. Therefore the charge goes back and forth between protons and neutrons.

Now, I know the book is rather old, but I wonder if this is still current. it sounds like typical weird quantum-level behavior.

What I wonder in the dark matter problem, is whether electrons from decaying neutrons can be accounted for precisely enough to determine the neutron's half life. I assume not, or this would have been done already. But I don't know.
Fresh out of clues. Did you really expect anything?
February 19th, 2018 at 8:37:21 AM permalink
Nareed
Member since: Oct 24, 2012
Threads: 345
Posts: 12529
I just realized the assumption that dark matter is made up of WIMPs (Weakly interacting Massive ParticleS) might be wrong in a very particular way.

The thing is that particles in the Standard Model, normal matter, interact in a number of ways. I don't now whether all can interact with all, but I know many interact with many, given they are all governed mainly by 3 of the 4 fundamental forces: electromagnetism, the Strong nuclear force, and the Weak nuclear force. The fourth force, gravity, does affect them, but not their interactions.

About the most weakly interacting particle we know of is the neutrino. it's produced in a variety of ways, including in particular during nuclear fusion. This means the Sun constantly irradiates the Earth with many, many, many neutrinos. Of these, only a small number ever interact with particles on Earth. We know this due to the detection rates in neutrino detectors. The dark matter WIMPs would be less interactive than that.

But suppose dark matter particles do interact, but only through forces that do not affect normal matter particles?

Sure, there are many problems with this suggestions, foremost we don't know about the existence of any other forces. I feel a bit like I'm invoking the God argument: we can't detect other forces because they don't affect normal matter. Suuuuuuure!

But it's something to think about. The strong nuclear force has been responsible for our very lives since long, long, long before the Solar System formed, yet we were utterly unaware of it til the XX Century.
Fresh out of clues. Did you really expect anything?