The Many Ways to Search for Dark Matter (with a picture of Luna) · 8:47pm Jul 21st, 2017
Ferret kindly suggested I should do a post here to notify readers whenever I post something on my new Particle Physics Gadgeteering blog. I am happy to do this, but I fear I run the risk of being seen to be spamming my followers with non-pony-related stuff. So in an effort to make it look vaguely legitimate, I will accompany such announcements with pictures of ponies. I have just posted something on The Many Ways to Search for Dark Matter, so you get a picture of the Princess of the Night.
They sought it with thimbles, they sought it with care,
They pursued it with forks and hope,
They threatened its life with a railway-share,
They charmed it with smiles and soap.Lewis Carroll
Dark matter has long been a popular subject choice for a public talk on particle physics or astronomy. Not only is it genuinely one of the biggest mysteries in modern science, but it is also a great story. The astronomical evidence that the majority of the galaxy is made from some unknown invisible substance is overwhelming. The theory that this missing matter consists of a new type of particle, only interacting weakly with ordinary matter, is the frontrunner explanation. It falls to particle physicists to test this hypothesis by searching for dark matter particles—a challenge which we accept with relish. Searching for new particles is our favourite sport, and this one is particularly big game. Unlike the short-lived particles discovered in recent decades, which decay in a tiny fraction of a second, a dark matter particle must be stable. These things have been hanging around the universe, pulling galaxies into shape, since shortly after the Big Bang. A verified detection would be a really big prestigious discovery for the team that did it.
We will see how long I can keep this up before I end up posting totally random pictures.
P.S. Or if you want the true pony fiction description of dark matter, see: The Dark Side (Codex Equestria)
(Unfortunately, it seems your image didn't come through - can you fix it?)
You know, I read that as The Particle Physics Gardening Blog
Twilight Sparkle looked around the empty section of rock farm and considered it against her knowledge (admittedly small) of farming. "So, Pinkie. Is this section of ground held fallow for some reason, or did it just get harvested?"
"Oh, no. This is our Sub garden." Pinkie bounced from place to place in the featureless expanse of dark soil, each time landing with only one hoof on the ground. "Don't flap your wings, Twilight, or you'll blow the crop all around. We have Fermitons in this section, and all kinds of Quarks over here, but--- No, Twilight! Don't walk there!"
Twilight Sparkle stopped abruptly about a half-heartbeat before she tried to stop, then tried to turn before she turned, and eventually looked over at her pink friend in complete perplexion. "?no gniog s'tahW !eikniP"
"The whole Chronoton harvest," she moaned. "Don't worry, Twilight! I'll go get an endochronic rake out of the shed and clear you a path out. Um... !thgiliwT ,kcab thgir eb ll'I !evom t'noD"
4608448
Chocolate would be dark energy.
Not sure what the image problem is, but I copied it to my deviant art sta.sh in case that's more reliable.
4608481
That has been done before. In fact it was a winner at the Chelsea Flower Show two years ago.
That's a nice picture of Luna, but that still doesn't make it pony-related, is it?
4608529 Shush you. I've seen less-pony-related on Derpibooru. This at least actually has a pony in it. Besides, I have a passing interest in particle physics.
Always a good choice.
4608604
I was speaking about the content of the blog entry he advertises here. It's not pony-related. But he attempts to make it pony-related by posting a pony picture. Which still doesn't make it pony-related.
I'd rather have him continue his pony physics entries.
How heavy are all the neutrinos that are flying around? In fact, how heavy are all the gravitons?
4608683 Pineta's a "she." And I love her pony physics posts even more, but as long as she's writing non-pony physics posts (and I can totally understand why), I don't mind her cross-posting them here.
4608683
Don't worry, I will be still be doing pony physics stuff. I wasn't going to be cross-posting, but since Ferret suggested it, I thought I'd give it a try. If it is unpopular I'll stop.
4608705
Nobody knows exactly how heavy neutrinos are, but not very. Not enough to account for any significant amount of dark matter. Gravitons (if they exist) are massless - since gravity seems to have an infinite range, it would be mediated by a massless particle. Gravitinos, however, are a dark matter candidate.
4608839
I'm not fussy about pronouns, but to clarify, I am male (I may invite confusion as I revel in the girliness of the show, and blog about feminism - sorry about that, but I don't mean to deceive anyone). Glad you love my posts.
4608974
For once, my gender-identifying instinct was right!
4608974 Do we know that gravity has an infinite range? It's pretty clear it at least has an intergalactic range, but neutrinos have mass and they can still get from the Magellanic Clouds to Earth at just under the speed of light. Do you know any way we could test that?
(And for that matter, what's the current status of the question of whether gravitons even exist?)
(And oops, sorry for the pronoun mistake! It might mean something when I'm subconsciously thinking "Blogs about feminism and getting more girls into science -> is female.")
A couple things Ive been trying to find is, on average, how many neutrinos are there per cubic metre of space, assuming as they fly out of the volume, others fly in and occasionally there some emmision, absoption due to reactions but so small to not bother at 1% measurements, and if one value I saw was 4eV, or near UV, what mass energy equiv was that. what small proportion would photons therefore have also?
If the measurement of gravitational field gave quantisation energy levels of 700 Hz, what would be the maximum range of a particle of that energy,a nd so the maximum range of gravitons?
4609158
Well general relativity - the best theory of gravity we have - describes things very well on the scale of the Universe, which may or may not be infinite. Whether a theory of quantum gravity would is an open question as such a theory has yet to be developed. There has always been an alternative explanation to the dark matter problem - maybe gravity works different on galactic scales? - but such theories have gone out of fashion of late as they don't fit all the data. The neutrinos from supernova SN1987a did set a limit on their mass - it's very small - (and there are also other ways to do this) which is one reason why they have been ruled out as a dark matter candidate.
4609168
The sun is the biggest source of neutrinos, which according to wikipedia gives a flux of 7×107 neutrinos per cm2 per second. If you really want to go into the calculations, there's some more information here: https://masterclass.icecube.wisc.edu/en/learn/detecting-neutrinos
I'm not the person to ask about gravitons. I'm a detector scientist, so I only work on things we can detect.
4609301
If you build detectors, then I wish I could list a coherent set of links that demonstrate what I believe the possibility of arrays that can pick up 4 spacial dimentional wave fronts, by using solutions to the packing problem. After all, its only when you accidentally see something, or try something new that you find you just discovered Reals when all you were looking at before were Cardiinals?
Does that mean you use aliminium tracks instead of copper due to the lower atomic mass?
I personally hope you keep crossposting (Since I suggested it and all) and this is really intriguing.