[HN Gopher] 'Impossible' particle discovery adds key piece to th...
___________________________________________________________________
'Impossible' particle discovery adds key piece to the strong force
puzzle
Author : theafh
Score : 153 points
Date : 2021-09-27 14:40 UTC (8 hours ago)
(HTM) web link (www.quantamagazine.org)
(TXT) w3m dump (www.quantamagazine.org)
| dmbaggett wrote:
| I'm curious: could anyone knowledgeable share a bit about these
| QCD lattice models -- are they incredibly complicated? Are there
| open source implementations of these models and if so, would the
| code make any sense to a non-physicist programmer?
| maxnoe wrote:
| A Quick search found this: https://github.com/akio-
| tomiya/LatticeQCD.jl
|
| Not my field of expertise though, I am in experimental gamma-
| ray astronomy
| ahefner wrote:
| I've wondered this too, and if it's possible for a toy
| implementation to help teach the concepts, but I suspect not.
| Probably the translation to code obscures more than it
| illustrates.
| evanb wrote:
| You might enjoy Lepage's "Lattice QCD for novices" which
| develops a lot of the ideas without getting bogged down in
| the specifics of QCD (it focuses on the harmonic oscillator +
| a harmonic oscillator).
|
| [0] https://arxiv.org/abs/hep-lat/0506036
| rrss wrote:
| > Are there open source implementations of these models
|
| there are some open source packages for lattice QCD. e.g.
| https://jeffersonlab.github.io/chroma/
| zbyszek wrote:
| Goodness me, that's a blast from my very distant past! The
| venerable MILC code is still available:
| https://web.physics.utah.edu/~detar/milc/milc_qcd.html
| dmbaggett wrote:
| Also found this GitHub topic page:
| https://github.com/topics/lattice-qcd
| lisper wrote:
| > are they incredibly complicated?
|
| That depends on what you mean by "complicated". Conceptually
| they are not too bad, it's basically just quantum field theory
| (which some might consider "incredibly complicated" so YMMV).
| But the devil is in the details. From the article:
|
| "While physicists know the exact equation that defines the
| strong force -- the fundamental force that binds quarks
| together to make the protons and neutrons in the hearts of
| atoms, as well as other composite particles like tetraquarks --
| they can rarely solve this strange, endlessly iterative
| equation, so they struggle to predict the strong force's
| effects."
|
| > Are there open source implementations of these models
|
| That I don't know.
|
| > and if so, would the code make any sense to a non-physicist
| programmer?
|
| Having seen code written by scientists, I can confidently
| answer this with: almost certainly not.
| datameta wrote:
| >Having seen code written by scientists, I can confidently
| answer this with: almost certainly not.
|
| Got a kick out of that, thanks. I think there is a kind of
| compartmentalization of environments going on when one
| engages in scientific programming. It seems to often be
| structured more akin to math than code. I once worked with a
| brilliant multitalented individual who held a PhD in a
| specific field of physics that I cannot recall. In one
| instance they ported the orchestration software for a
| supercomputer from python into java, in a _week_. It was
| beautiful to read. This same person used single letter
| variables in their ML models and had virtually zero comments
| which made it somewhat difficult for me to follow their
| updates after a week of having not seen the code.
| tsimionescu wrote:
| This reminded me of the chemical PhD who created Clasp, a
| full common lisp implementation using LLVM as a JIT
| compiler, able to call even template C++ code from Common
| Lisp (a feat which no other language I know of even tries,
| except perhaps .NET with managed C++).
|
| [0] https://github.com/clasp-developers/clasp
| ethbr0 wrote:
| To me, it's a difference in professional gestalts(?) in
| highly trained individuals.
|
| Physical engineers, especially, have a very formalized,
| standardized way of looking at the world. They all share
| it, and so their code follows from that.
|
| Physicists, biologists, software developers all have
| different ways of looking at the world (some more
| standardized, some less). Our code follows from that.
|
| So while we may gripe they don't leverage (insert language
| arcana / convention), my intuition is our code would still
| look very different even if they did. Biggest example, as
| you point out: math-structured code, from math-heavy
| disciplines.
| NineStarPoint wrote:
| From what I've heard the core of the issue is it's similar
| to non-online game development. Most scientists make some
| programs for a single paper, and then just start from
| scratch for a new project. When you don't have to care
| about long term maintainability readability becomes much
| less of a concern to people.
| lisper wrote:
| Here's an analogy that I can speak from more direct
| experience: if you study the theory of elliptic curves, and
| then look at elliptic curve cryptography code, there will
| appear to be no connection between the two. This is because
| in between the theory and the code are a zillion
| implementation details and tricks of the trade that aren't
| generally mentioned in the theory. Add to that the fact
| that the people who write scientific code aren't coders by
| trade, so they learn to write code that is just good enough
| but no better, and the result is something that looks like
| a horrible mess. (Also, the code is often written by grad
| students, so that makes it even worse. I look back on some
| of the code that I wrote back when I was a grad student
| that was the basis for publications and I shudder.)
| andi999 wrote:
| The Fortran code at particle research groups I saw looked
| pretty solid to me.
| lisper wrote:
| "Fortran" and "solid" are not two words that go together in
| my mind ;-)
|
| But the OP didn't ask if the code was _good_ (or "solid"),
| they asked if it would make any sense to a non-physicist
| programmer. And the answer to that question, I'm guessing,
| is most likely not. But I would be very happy if I turned
| out to be wrong about that.
| andi999 wrote:
| It probably boils down to if there are any non physicist
| Fortran programmers...
| evanb wrote:
| I'm a LQCD practitioner.
|
| There are a variety of open-source implementations; I'll just
| point to a few. The one funded by the Department of Energy
| through the SciDAC program is the USQCD software stack [0].
| There's also the GPU library quda, which is maintained by
| Nvidia employees (and others in the community). There's Grid
| [2], development led by Edinburgh in close collaboration with
| intel (to make sure it compiles down to sensible high-
| performance primatives). There's openQCD [3], coordinated by
| CERN researchers.
|
| As to whether it'll be readable to you---maybe? How transparent
| each library is differs. The most important parts are typically
| (1) the generation of gauge configurations (typically by HMC,
| which was discovered by the LQCD community [4]), which are MCMC
| samples and (2) the calculation of observable on each sample.
| Both rely on highly optimized (and preconditioned, and maybe
| multigrid-ed) linear solves---the most important kernel.
|
| Some libraries are written to be as transparent as possible;
| some to be as portable as possible. All are written to handle
| massive data parallelism across hundreds of high-performance
| nodes with some mixture of OpenMP, MPI, #pragma acceleration,
| etc.
|
| Finally, the code will only "make (big picture) sense" to you
| if you understand lattice quantum field theory.
|
| [0] http://usqcd-software.github.io/ [1]
| http://lattice.github.io/quda/ [2]
| https://github.com/paboyle/Grid [3]
| https://luscher.web.cern.ch/luscher/openQCD/ [4]
| https://www.sciencedirect.com/science/article/abs/pii/037026...
| jerf wrote:
| I'm not an expert on particle physics, but the verbiage sounds
| to me like one of the standard problems in physics: We can
| write the differential equations. But even simple differential
| equations can be unsolvable. For example, consider the simple
| Three Body Problem. The differential equations are simple
| enough that you can use them as an introduction to the concept
| of differential equations themselves, but the Three Body
| Problem is not in general solvable.
|
| The three body problem can generally be acceptably approximated
| for a reasonable period of time. But that problem only involves
| inverse squaring of distances. Strong forces decay much faster
| than that, which makes them more sensitive to errors. Plus you
| end up with one of the fundamental problems we have trying to
| understand our universe, which is just how monstrously enormous
| and monstrously slow we humans are. We operate at "meter"
| scales and "second" time frames, and particle physics operates
| at somewhere around 30 and 40 _orders of magnitude_ smaller,
| respectively. (Not quite all the way down to the Planck sizes,
| but closer to those than to the macroscopic world.) So when you
| try to numerically approximate the differential equations, you
| don 't get very far in time or space before your approximations
| have critically diverged from reality.
|
| It's like we're trying to work out the fundamentals of
| chemistry and our primary tool is smashing planets together.
| crznp wrote:
| Well put, though one nitpick: the three body problem is
| solved. It illustrates another case: even if a solution is
| known, it might not be practical.
|
| https://www.math.uvic.ca/faculty/diacu/diacuNbody.pdf
| klodolph wrote:
| When people say that the three-body problem is "unsolvable"
| they really mean that there's not a way to write out an
| analytic solution to the problem. In the same way, you can
| call quintic polynomials "unsolvable", because there's no way
| to take arbitrary quintic polynomial equations and express
| the solutions as ordinary algebraic formulas.
|
| However, it's very misleading to call quintic equations
| unsolvable, because we know where the solutions are, and we
| can use various numeric methods to calculate the solution
| with arbitrary precision. Any time we can calculate the
| answer with as much precision as we want, I'd like to say
| that the problem is "solved" in a very real and meaningful
| way.
|
| The problem is worse with quantum mechanics. With quantum
| mechanics, not only do we lack analytic solutions to many of
| the equations used in QM, but we also lack good numeric
| solutions (using real hardware, at least).
| ethbr0 wrote:
| Following the analogy, as a layperson, what's the nature of
| the difference with quantum mechanics that doesn't allow it
| to be solved to arbitrary precision (even if through brute
| force iteration)?
|
| Is it that we haven't discovered the solution generating
| algorithms? That the state/probabilities of quantum
| mechanics are fundamentally untenable to similar
| calculation? Or something else entirely?
| evanb wrote:
| Many problems in physics are perturbative. Then,
| approximate methods suffice to get reliable answers. In
| Asimov's "relativity of wrong" it's the perturbative
| nature of gravity---gravity is very weak---that makes
| "the Earth is a sphere" less wrong than "the Earth is
| flat". So, if you need an answer to only such-and-such
| precision, the approximation scheme lets me know how hard
| I must work to achieve reliability at that scale. Once I
| get the precision I need I can stop.
|
| Electrodynamics is like that. There is a number, the fine
| structure constant, about 1/137, that gives the natural
| scale for how big the next step in the approximation is,
| compared to the size of the current step. So, if I need
| to know the answer to 1 part in 10^9, I'm going to need
| to do 4 or 5 steps of fixing up the approximation (each
| fix, of course, being a great deal more arduous).
|
| QCD, and other "strongly coupled" or "non-perturbative"
| problems are not like that. If you make the dumbest
| approximation (flat-earth) and then fix it up a bit
| (sphere earth), answers don't change just a little. They
| change completely. In QCD the number that characterizes
| the "obvious" approximation (the Feynman diagram
| approach)---the number that's 1/137 for electrodynamics
| ---is about 1.5. That's a disaster! The approximation
| scheme is obviously no good---you learn that you can
| never stop improving your approximation, because if you
| only worked "a little harder" your answer could change
| completely.
|
| Other approaches are required.
| klodolph wrote:
| It's nothing fundamental, as far as I am aware. Depends
| on what you mean by "fundamental".
|
| There is no known way to simulate a quantum computer,
| using a classical computer, in polynomial time. A quantum
| computer is just a kind of quantum system, so we know
| that some quantum systems cannot be efficiently modeled
| (barring revolutionary advances in simulation
| algorithms).
|
| When your simulations take superpolynomial time, it tends
| to be easy to find problems which you simply do not have
| the computational resources to solve, and you may not be
| able to solve interesting versions of the problem. There
| are lots of examples of problems like this. However, I
| don't consider this to be a fundamental difference.
|
| For example, satellite navigation systems are just fine
| calculating directions for driving all the way across the
| continental US, even though that's a very "large"
| instance of the problem that they are solving. But if you
| try to find the fastest route for a delivery driver to
| make a hundred deliveries within one city, good luck.
| This is just an analogy, and I'd like to emphasize that
| "no KNOWN algorithm" efficiently solves these problems,
| and that we haven't proven whether such an algorithm
| exists.
| ethbr0 wrote:
| Thanks! By "fundamental," I was curious about the nature
| of the problem's difficulty, moreso than the progress on
| solutions. And computational intractability due to system
| properties makes sense!
| zardo wrote:
| Also a layperson, but as I understand it. We do have the
| algorithms to simulate quantum systems with n states to
| arbitrary precision through brute force. But they require
| that you can put ~n bits into a superposition state.
|
| If your computer doesn't have that capability, you can
| simulate it to arbitrary precision with ~2^n bits.
| nabla9 wrote:
| These articles don't make clear distinctions between discoveries
| standard model framework, and completely new physics.
|
| This seems to be discovery within standard model. A new composite
| particle.
| stared wrote:
| It is my general impression with Quanta Magazine: an
| interesting phenomenon + a clickbaity title and headline
| (bordering on crackpotty).
| kordlessagain wrote:
| Finally, warp drives.
| esarbe wrote:
| Interesting read. But I'll wait for what Sabine has to say about
| it. :D
| tux3 wrote:
| Superdeterminism predicts that it was always pre-determined I
| wouldn't really understand this article, and the universe left
| me no choice, so I have nothing to feel bad about.
|
| Sabine's blog exists in an interesting superposition of
| comforting and existential dread =]
| ryan93 wrote:
| weird that people love to fanboy/fangirl anyone who has a
| reputation for criticism.
| Koshkin wrote:
| Why is it weird? Criticism draws attention.
| ryan93 wrote:
| She's not even an expert in this subject but she has name
| recognition so OP wants her opinion. Just weird.
| esarbe wrote:
| OP is not a physicist and Sabine is able to break down
| the problems and issues with many of the scientific and
| unscientific theories that are thrown around so that even
| a layperson can follow the rational.
|
| So, I get the drift of the article. Do I have enough
| knowledge to make any reasonable assumptions about the
| validity of the findings it presents? Nope, not at all.
|
| That's why I cherish Sabine. She's down to earth and has
| an understanding of science that suits me. She's
| definitely more than enough physics under her belt[0] to
| be qualified to talk about these topics. Go away with
| your 'She not an expert'. Have you seen her
| qualifications?
|
| "Naw," I hear you say "she's a theoretical physicist, not
| a particle physicist."
|
| Yeah, well. I'm a Software Engineer. I can still tell if
| a Network Engineer tells bullshit.
|
| I do understand why some people hate on her; she's
| abrasive and irreverent. Some people don't like their
| ivory towers to be besmirched.
|
| [0] https://portal.dnb.de/opac/simpleSearch?reset=true&cq
| lMode=t...
| Mizza wrote:
| I like Sabine, but I found her "takedown" of the multiverse/MWI
| ignored the most compelling argument for it, the computational
| argument proposed by Deutsch, and that was enough to make me
| skeptical of her other positions. Anybody know if she's ever
| addressed that anywhere?
| naasking wrote:
| What is the computational argument?
| spullara wrote:
| https://www.newyorker.com/magazine/2011/05/02/dream-machine
| naasking wrote:
| I figured this might be the "quantum computation is
| computation done on parallel worlds". It just isn't that
| compelling [1], and is in fact arguably false [2]. That's
| probably why Sabine didn't touch on it.
|
| [1] https://www.sciencedirect.com/science/article/abs/pii
| /S13552...
|
| [2] https://arxiv.org/abs/1110.2514
| Mizza wrote:
| Both of those papers, and others like it, are by single
| authors in philosophy journals, not physics journals. I
| don't think they are 'serious' in the same way. That
| Arxiv one is particularly bad.
| naasking wrote:
| "Particularly bad" in what sense? The notion that quantum
| computation happens in parallel universes _is a
| philosophical position_ , not a scientific one, so of
| course philosophers of science are evaluating it.
| Mizza wrote:
| It introduces the fundamental question but never answers
| it. He quotes Deutsch partially, "explain how Shor's
| algorithm works" - but doesn't answer this question. He
| also leaves out the important part of the quote:
|
| "To those who still cling to a single-universe world-
| view, I issue this challenge: explain how Shor's
| algorithm works. I do not merely mean predict that it
| will work, which is merely a matter of solving a few
| uncontroversial equations. I mean provide an explanation.
| When Shor's algorithm has factorized a number, using
| 10^500 or so times the computational resources than can
| be seen to be present, where was the number factorized?
| There are only about 10^80 atoms in the entire visible
| universe, an utterly minuscule number compared with
| 10^500. So if the visible universe were the extent of
| physical reality, physical reality would not even
| remotely contain the resources required to factorize such
| a large number. Who did factorize it, then? How, and
| where, was the computation performed?"
|
| Computation is real - it requires matter and energy. If
| Shor's algorithm can factor a number so large that it
| would require more matter than there is available in the
| universe: _where is the computation occurring_? I have
| never seen this plainly addressed. I'm a layman, of
| course, which I why I would hope she'd break this
| argument down in her MWI video.
| jessaustin wrote:
| _There are only about 1080 atoms in the entire visible
| universe..._
|
| Should this be read as 10^80? The way it's written is
| confusing.
| trenchgun wrote:
| Indeed.
|
| Those sentences should be like this: "When Shor's
| algorithm has factorized a number, using 10^500 or so
| times the computational resources than can be seen to be
| present, where was the number factorized? There are only
| about 10^80 atoms in the entire visible universe, an
| utterly minuscule number compared with 10^500."
| trenchgun wrote:
| You dropped these: ^^^
| naasking wrote:
| > but doesn't answer this question
|
| The author doesn't have to answer that question to
| dispute Deutsch's alleged answer.
|
| Secondly, Deutsch's challenge of explaining Shor's
| algorithm presupposes that quantum computation requires
| an explanation _in terms of classical computation_. While
| I 'm sympathetic to that view, this assumption is easily
| rejected by people who don't view reality as
| fundamentally classical or local. So for these people,
| there is no challenge to meet.
|
| Thirdly, while you can speculate that Shor's algorithm
| will scale to factoring numbers so large they require
| more atoms than are in the universe, _no one has
| demonstrated that this is the case_. Just because our
| current _models_ describe this happening, that _doesn 't
| mean the model corresponds to what will actually happen
| in reality_. It could easily be the case that the model
| is not accounting for noise or other factors that will
| prevent entanglement from scaling to the levels you
| describe. This is the position of some determinists, in
| which case Deutsch's challenge is also neutered.
|
| Finally, other interpretations of QM can also provide
| explanations for speedups. For instance, any
| interpretation of QM that accepts its non-locality has an
| escape hatch via relativity: non-locality is effectively
| time travel in GR, but in a form that cannot be exploited
| for superluminal signalling. There are many other
| possible answers given by other interpretations of QM.
|
| I personally think it's an interesting question, but it's
| not a compelling argument for many worlds, not least
| because the "many worlds as parallel computations"
| doesn't actually work beyond trivial examples.
|
| > Computation is real - it requires matter and energy.
|
| Yes, _classical_ bits require a certain amount of matter
| and energy, but _qubits_ do not have the same matter and
| energy requirements, which seems to be what you 're
| expecting. If you expect there to be an answer of this
| sort, then I think you must give up believing that
| quantum computation will scale. Basically, you are
| expecting reality to actually be classical, and so have
| some deterministic classical computation happening behind
| the scenes (hidden variables), and these hidden variables
| will more than likely disrupt scaling quantum
| computations.
| leephillips wrote:
| Well, you should be skeptical in general, no? What's the
| alternative, just adopting some other person's opinions?
|
| If this is about Sabine Hossenfelder, she has opinions and
| she has arguments. Sometimes she's right, sometimes she's
| wrong. Like everyone. Sometimes her opinions are well
| supported, sometimes I think not. Some of her explanations
| are sound, others contain mistakes.
| cmeacham98 wrote:
| I've never read Sabine Hossenfelder, so I can't comment
| specifically on her.
|
| However, life is about trusting other people and adopting
| their opinions. I do not have the time or energy to be an
| expert on every subject, so naturally I will have to read
| the opinions of other people who have spent time in that
| particular subject.
|
| Someone's previous record of factual accuracy as well as
| considering reasonable opposition to their points obviously
| will affect how much I trust them to influence my
| worldview, and how likely I am to believe what they say is
| true.
| Amin699 wrote:
| The tetraquark now presents theorists with a solid target against
| which to test their mathematical machinery for approximating the
| strong force. Honing their approximations represents physicists'
| main hope for understanding how quarks behave inside and outside
| atoms -- and for teasing apart the effects of quarks from subtle
| signs of new fundamental particles that physicists are pursuing.
| NovaS1X wrote:
| Can anyone informed and eager enough tell me how it's possible to
| measure something that only exists for "12 sextillionths of a
| second"? In my computer minded mode of thinking in sensors and
| clock cycles I can't imagine a way this is done.
| frob wrote:
| The answer is you don't measure the particle directly, but
| instead measure its byproducts. I spent my graduate career
| studying the Upsilon meson, which is a particle dominated by
| two valence bottom quarks. The Upsilon exists for a similar
| amount of time and there is no way we can measure it directly.
| However, about 3% of the time, it will decay to a pair of
| highly energetic electrons and another 3% of the time, it will
| decay to a pair of muons. These extremely energetic leptons
| (think 99%+ the speed of light) are something we can detect as
| they come screaming out of the collision. (side note: an
| electron weighs ~ 511 keV in particle physics units. The
| Upsilon meson weighs at least 9.46 GeV depending on the state.
| That means each electron has at least 4.73 GeV of kinetic
| energy with a mass of 511 keV, or ~9000x more kinetic energy
| than its energy in mass). We have ways of measuring their
| energy, so we can reconstruct the mass of the original particle
| via $E=mc^2$ plus some kinetics.
| im3w1l wrote:
| Something I never quite understood: When you shoot particle A
| at particle B in some accelerator, how does the formation-
| and-almost-immediate-decay of particle C affect the end
| result? Like how can we know that those leptons didn't just
| come from the initial collision?
| NovaS1X wrote:
| This is a great answer. Thank you.
|
| So in these situations how do you tell apart electrons from
| one source compared to another? In the article they mention
| how the LHC collides particles at a rate of "40 million times
| each second". I can imagine there are a lot of electrons and
| other particles flying around from other collisions. What
| makes an electron discernible between one type of particle
| and another?
| frob wrote:
| Truly, you never really know which pair of particles came
| from a specific decay, and which come from some other
| processes and just happen to line up with the mass/energy
| you're looking at. Fortunately, for most particles, the
| combinatorial background signal follows a smooth curve
| around the energies you're looking at, so you can fit a
| curve to that background signal and then attribute the rest
| of the signal to the particle production. For an example,
| see the main plot on the Upsilon page in Wikipedia
| (https://en.wikipedia.org/wiki/Upsilon_meson). You can see
| there is a linear decline (in log space) of the background
| signal but then there's another peak around 9.5 GeV which
| is the additional signal from the Upsilon decay.
|
| The point is, we cannot tell which pair of electrons/muons
| come from the decay of a specific particle, but we can tell
| how many extra occurred beyond what we would expect from
| all other known processes.
| NovaS1X wrote:
| Thanks so much for the explanation and the example. I at
| least know a little more about these complicated
| endeavours now.
| frob wrote:
| Happy to do it! Thanks for asking insightful questions.
| :)
| retbull wrote:
| Statistics like the op said. If you are expecting your
| decay products from an interaction to be 20% X and 80% Y
| but after 100 billion attempts which should have averaged
| out to the expected outcome you instead get 21% X and 79% Y
| something in your calculation is wrong.
| beambot wrote:
| Are the decay modes (3% one way, 3% another, 94%?)
| experimentally determined, or does theory predict this
| distribution?
| frob wrote:
| As in most things with particle physics, it's a combination
| of both. Theory predicts a wide band and then
| experimentalists come in with the best estimate they can
| make. Some theories are excluded and other are refined.
| There are another round of predictions and when the
| experiments get powerful enough, they can challenge or
| support some predictions.
|
| Some of the best data for branching ratios comes from e+e-
| (electon-positron) colliders such as LEP (literally, the
| Large Electron-Positron collider). In these colliders, we
| can fine-tune the energy to produce massive amounts of
| particles we care about. From that, we can see how they
| decay. Mostly, Upsilons decay into massive sprays of
| hadrons and leptons (called jets in particle physics).
| These can come from decaying Tau particles (the much much
| heavier cousins of muons and electons) or from
| quarks/hadrons decaying over and over and over again into
| things like Kaons, pions, muons, electrons, photons, and
| other lightish particles. In the relatively clean
| environment of a e+e- collider, we can reconstruct these
| jets and determine which may have come from Upsilons.
| Combining this with a whole bunch of other measurements
| (and some theory) lets us determine the branching ratio
| (how often a particle decays into certain things).
| japhyr wrote:
| I did an undergrad in physics, and at one point I wanted to
| be a particle physicist. But I didn't want to go straight to
| grad school, so I spent a couple years teaching middle school
| math and science. I loved that, and spent 25 years teaching
| instead of going back to physics.
|
| If you don't mind my asking, what are you doing now after
| spending years studying such a specific area of particle
| physics?
| [deleted]
| frob wrote:
| I've been a software engineer for the better part of a
| decade now. My areas of focus during that time have been
| NLP, messaging, teaching, politics, and now data analysis
| and processing around criminal justice.
| jxy wrote:
| s/mass/rest mass/g
|
| It's 511 keV at rest, and you are sensing a 4.73 GeV electron
| coming out of the decaying Upsilon. E=m and c=1 in the units
| you are using.
| PicassoCTs wrote:
| frobs answer is of course right, but theoretically - given
| enough resources, almost all phenomena should be observable.
| Imagine having a oscilloscope which measures once every 100 ms
| (Really slow i know). Now all you need is a 100 oscilloscopes,
| put in a phalanx seperated 1 ms each and a way to measure their
| clocks drifting. Given good enough "stitching" algos, any event
| above the theoretical limit of the nyquist theorem should be
| observable.
|
| https://en.wikipedia.org/wiki/Nyquist%E2%80%93Shannon_sampli...
|
| This answer simplifies alot and of course,one only gains a
| stop-motion picture show of the observed phenomena, but none
| the less..
| gizmo686 wrote:
| It isn't. They measure the decay products and infer what
| happened.
| NovaS1X wrote:
| That makes sense. Thank you.
| carbocation wrote:
| > Polyakov's analysis suggested that the four quarks banded
| together for a glorious 12 sextillionths of a second before an
| energy fluctuation conjured up two extra quarks and the group
| disintegrated into three mesons.
|
| Poetic and informative. What a sentence.
| [deleted]
| wiz21c wrote:
| I feel out of my element.
|
| https://www.youtube.com/watch?v=ks072waMayk
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