9 ms·

Furthermore, both teams measured a rate for the decay that is consistent with the Standard Model prediction, within the current precision of the measurement. A

Furthermore, both teams measured a rate for the decay that is consistent with the Standard Model prediction, within the current precision of the measurement. And now everyone: Noooo, not again. (Explanation: it's well-known that the Standard Model can't be completely correct but again and again physicists fail to find an experiment contradicting its predictions, see https://en.wikipedia.org/wiki/Physics_beyond_the_Standard_Model https://en.wikipedia.org/wiki/Physics_beyond_the_Standard_Mo... for example)

yohann305 8y ago
I honestly don't get the "No, not again". Could you elaborate? Thanks edit: thanks for the explanation
- cozzyd 8y ago
  There are many ways to extend the standard model and it would be nice to have additional constraints on the extensions (which would come from observing behavior not described by the standard model).
  - wolfgke 8y ago
    > There are many ways to extend the standard model and it would be nice to have additional constraints on the extensions (which would come from observing behavior not described by the standard model). For any experts reading this: what are plausible-looking extensions of the standard model which can probably be challenged/"proved" by current generation accelerators (in particular the LHC) and would lead to interesting extensions of the standard model? As far as I am aware, the LHC could e.g. find no sign of lots of variants of supersymmetry, which was a plausible candiate for this in the past: > https://www.scientificamerican.com/article/supersymmetry-fails-test-forcing-physics-seek-new-idea/ https://www.scientificamerican.com/article/supersymmetry-fai... > https://www.quantamagazine.org/complications-in-physics-lend-support-to-multiverse-hypothesis-20130524/ https://www.quantamagazine.org/complications-in-physics-lend...
    - cozzyd 8y ago
      I'm no theorist, so this is perhaps my jaded view, but right now my impression is that the phase space of theories is too large for someone to have a single prediction. The situation seems more like the LHC experiments are looking for ANY potential discrepancies with the standard model and then theorists will happily write up some reason for why it has to be that way. I went to a conference a few years ago where the LHC experiments announced that previous hints of a discrepancy with the SM evaporated with more statistics, which resulted in a whole session of theorists having to cancel / completely redo their talks.
      - the8472 8y ago
        > The situation seems more like the LHC experiments are looking for ANY potential discrepancies with the standard model and then theorists will happily write up some reason for why it has to be that way. Until recently they were mostly looking for specific deviations predicted by extensions. They only recently announced that they're now going for a broader search.
      - whatshisface 8y ago
        >theorists will happily write up some reason for why it has to be that way. They'll write down a model that describes it, which is all theorists' job to begin with.
- izzydata 8y ago
  I imagine they can't improve upon the standard model if everything they find never contradicts what they already know. Or rather what they can already conclude by the standard model.
  - k__ 8y ago
    Are there so many parts that could be wrong?
    - proaralyst 8y ago
      Crucially: it really doesn't work with gravity or relativity.
      - jcranmer 8y ago
        The standard model incorporates special relativity, but you're right in that general relativity doesn't mesh with the standard model.
      - danbruc 8y ago
        To avoid confusion, relativity must be read as general relativity, the standard model is a relativistic quantum field theory and hence takes special relativity into account.
        evanb 8y ago
        You can even formulate the standard model on a curved background metric that arises from GR. Just don't try to make the metric itself dynamical.
    - chriswarbo 8y ago
      As well as ignoring gravity, the standard model also doesn't predict or explain any of those observations labelled "dark matter" and "dark energy". We can add an extra parameter to general relativity (known as the "cosmological constant") to describe "dark energy" observations via a kind of 'anti gravity'; although we still don't fully understand what that means, or whether it's a correct description. It's also unclear whether this would have anything to do with quantum theories (like the standard model). General relativity can explain "dark matter" observations by assuming there is more mass/matter than we can see (i.e. it's electrically neutral and doesn't interact with light). Since the standard model tries to describe all of the fundamental constituents of matter, and forces including electromagnetism (light), having nothing to say about such a seemingly large amount of stuff is a rather large discrepancy in the standard model. AFAIK the standard model also says that neutrinos have zero mass; yet we've observed them undergoing radioactive decay ("neutrino oscillation", where each sort of neutrino can decay into the others). Particles which decay require some amount of time to do so. Particles with zero mass always travel at the speed of light (like photons, and hypothetical gravitons) and hence don't experience any time passing (this sentence is a consequence of special relativity). So particles with zero mass can't decay, so neutrinos can't have zero mass. I don't think we've measured their mass very accurately yet; we know it's very small, but it cannot be zero.
- Will_Parker 8y ago
  > I honestly don't get the "No, not again". Could you elaborate? As the cosmologist Sean Carroll said in his podcast, particle physicists haven't really been surprised by an observation since the 1970s. Presumably many were hoping for a surprise.
- asdfman123 8y ago
  If I have a conversation with you and you agree with everything I say, I learn nothing. If we have a conversation and you reveal that my assumptions are wrong, I can go back, rethink everything, and come out with a stronger world view. Basically, this experiment didn't tell scientists anything they didn't already know, or didn't prove them wrong--which might lead to newer, more interesting models that reveal more about the universe.
ainar-g 8y ago
Does this increase the likeliness that we need a bigger collider to finally reach new physics?
- jug 8y ago
  I wonder if it’s harder to get funding for that. With the LHC they at least expected the Higgs boson. And hopes for super symmetry signs that seem to have failed to materialize. With only hand waving and hopes for hypotheses left, and ever increasing costs... :-/
  - ISL 8y ago
    The easy ask now is for a precision electron-positron collider to study the Higgs itself. Lepton/anti-lepton colliders are as clean as an experiment can be, in stark contrast to hadron colliders, which are as clean as a car accident. With the improved understanding of the Higgs that we have now, an e+/e- machine can be custom-built to study it in great detail. The Higgs is the newest fundamental particle to physics, and the first/only known scalar. We should expect that it has more to tell us than simply its own existence. Even when the LHC was being planned, LHC was the discovery machine, and precision experiments were to follow. In my opinion, only when those measurements are complete should we consider a huge leap toward higher energy, unless new accelerator technology emerges.
    - wolfgke 8y ago
      > The Higgs is the newest fundamental particle to physics, and the first/only known scalar. A question to physicists: Is there (strong) evidence that there might exist other scalars (if yes: at which energy level?). If not: Do there exist attempts of theories that predict why there is only one scalar?
      - ISL 8y ago
        I'm unaware of a particular compelling argument for another scalar. Scalars are easier for theorists to use when trying out a new theory, so they abound in theoretical physics. At some level, it is something of a surprise to have found that there is just one particle responsible for the Higgs mechanism, and it is indeed spin-0, as Nature hasn't given us one of those before. Prior to the discovery of the Higgs, perhaps the majority of physicists were betting on something Higgs-like, but not quite the pure vanilla Standard Model Higgs. I would not bet any money on it, but if one were looking for another scalar, one might find it in whatever mechanism underlies dark energy. Many theoretical models for dark energy use scalars, again, because they are easier...
delhanty 8y ago
Sorry, I don't understand this point. If a model of the universe was completely correct, wouldn't it have equivalent complexity to the universe and hence not be a model?
- jon_richards 8y ago
  No? Think of the game of life. Low model complexity, high universe complexity.
  - deleted 8y ago
    [deleted]
  - digi_owl 8y ago
    I think the term used is emergent complexity. So when you go from particle physics to chemistry, new complexities emerge that can't be explained in the realm of particle physics alone (iirc). sadly certain "sciences" still cling to the idea that they can simply aggregate the results from multiple of their "particles" and get a solution for larger systems.
    - xoa 8y ago
      >So when you go from particle physics to chemistry, new complexities emerge that can't be explained in the realm of particle physics alone (iirc). Correct me if I'm misunderstanding, but I think you're confusing general theory vs practical applicable models here maybe? Yes, fundamental principles of interaction can combine at scale to create new large scale effects, but that doesn't change the fact that they came out of fundamental principles nor that they can't be "explained" via those principles. There is no magic that pops into existence up the chain. The asymmetry of water molecules and the way their electron clouds distribute create all sorts of fascinating effects in bulk water, but they're still directly coming out of physics of course. The issue in practice however is that the level of computing necessary to accurately model reality at scale from fundamentals matches or exceeds actually doing it in reality, and for us rapidly becomes absolutely, utterly infeasible for anything but the simplest systems. "New emergent complexities" absolutely "can be explained" from a correct lower level set of principles, but that doesn't mean we can actually crunch the math at any scale we want. So we need higher level bulk models too, at many levels all the way up, which are good enough to be effective approximations to a given level of accuracy in practical computing time. The low level fundamentals often at bulk average out due to random variance in sufficient quantity and are irrelevant to whatever we care about, so there is no need to do it that expensively (even if we could). But that isn't the same thing as the fundamentals being wrong somehow or not being at the root of everything above.
dukwon 8y ago
> within the current precision of the measurement The error bars are ±20%, so there's quite a lot of wiggle room for new physics.
f137 8y ago
Well, the standard model can be correct. It is correct until some experiment proves otherwise. It is full of unexplained hadcoded parameters, indeed, which need an explanation from outside of the SM.
- westurner 8y ago
  > It is full of unexplained hadcoded parameters, indeed, which need an explanation from outside of the SM. https://en.wikipedia.org/wiki/Magic_number_(programming)#Unnamed_numerical_constants https://en.wikipedia.org/wiki/Magic_number_(programming)#Unn... > The term magic number or magic constant refers to the anti-pattern of using numbers directly in source code
  - bradleyjg 8y ago
    Who is going to request changes when doing a code review on a pull request from God?
    - adrianratnapala 8y ago
      God doesn't use GitHub. You have to run `git format-patch` and email the results to Him.
      - eloff 8y ago
        Yeah him and Torvalds alike, maybe it's an ego thing. Or a graybeard thing?
    - dylan604 8y ago
      But which branch do you pull from? God has been forked so many times, it's hard to keep track. There are several distros available, so I guess you just get to pick the one that checks the most of your needs at the time.
- dwaltrip 8y ago
  The standard model has no conception of gravity, so it is most certainly incomplete, at the very least.
etatoby 8y ago
I've been told by a physicist friend of mine that one of the big problems is the amount of data produced by LHC sensor arrays. While the LHC is running, 600,000,000 particle collisions happen every second. Every collision produces particles that decay in complex ways into more particles, and so on. I forgot the numbers, but they have severals layers of filtering between sensors and long-term storage. First there are FPGA-based real-time filters, next to the sensors, which throw away most of the data as "noise." Then there are local CPUs which throw away most of the remaining data, again classified as "noise" or uninteresting. Finally, what remains (30,000 TB/year) is stored long-term to be later analyzed by physicists. All levels of filtering and analysis, from the FPGA to the physicist's algorithms, make use of the Standard Model itself and the rest of known physics to figure out what's "interesting" and what's "noise." One big problem is thus: how can we find new things if we are only looking for what we already know? Hence the need for machine learning and automatic pattern discovery.

yohann305 8y ago

I honestly don't get the "No, not again". Could you elaborate? Thanks edit: thanks for the explanation

cozzyd 8y ago
There are many ways to extend the standard model and it would be nice to have additional constraints on the extensions (which would come from observing behavior not described by the standard model).
- wolfgke 8y ago
  > There are many ways to extend the standard model and it would be nice to have additional constraints on the extensions (which would come from observing behavior not described by the standard model). For any experts reading this: what are plausible-looking extensions of the standard model which can probably be challenged/"proved" by current generation accelerators (in particular the LHC) and would lead to interesting extensions of the standard model? As far as I am aware, the LHC could e.g. find no sign of lots of variants of supersymmetry, which was a plausible candiate for this in the past: > https://www.scientificamerican.com/article/supersymmetry-fails-test-forcing-physics-seek-new-idea/ https://www.scientificamerican.com/article/supersymmetry-fai... > https://www.quantamagazine.org/complications-in-physics-lend-support-to-multiverse-hypothesis-20130524/ https://www.quantamagazine.org/complications-in-physics-lend...
  - cozzyd 8y ago
    I'm no theorist, so this is perhaps my jaded view, but right now my impression is that the phase space of theories is too large for someone to have a single prediction. The situation seems more like the LHC experiments are looking for ANY potential discrepancies with the standard model and then theorists will happily write up some reason for why it has to be that way. I went to a conference a few years ago where the LHC experiments announced that previous hints of a discrepancy with the SM evaporated with more statistics, which resulted in a whole session of theorists having to cancel / completely redo their talks.
    - the8472 8y ago
      > The situation seems more like the LHC experiments are looking for ANY potential discrepancies with the standard model and then theorists will happily write up some reason for why it has to be that way. Until recently they were mostly looking for specific deviations predicted by extensions. They only recently announced that they're now going for a broader search.
    - whatshisface 8y ago
      >theorists will happily write up some reason for why it has to be that way. They'll write down a model that describes it, which is all theorists' job to begin with.
izzydata 8y ago
I imagine they can't improve upon the standard model if everything they find never contradicts what they already know. Or rather what they can already conclude by the standard model.
- k__ 8y ago
  Are there so many parts that could be wrong?
  - proaralyst 8y ago
    Crucially: it really doesn't work with gravity or relativity.
    - jcranmer 8y ago
      The standard model incorporates special relativity, but you're right in that general relativity doesn't mesh with the standard model.
    - danbruc 8y ago
      To avoid confusion, relativity must be read as general relativity, the standard model is a relativistic quantum field theory and hence takes special relativity into account.
      - evanb 8y ago
        You can even formulate the standard model on a curved background metric that arises from GR. Just don't try to make the metric itself dynamical.
  - chriswarbo 8y ago
    As well as ignoring gravity, the standard model also doesn't predict or explain any of those observations labelled "dark matter" and "dark energy". We can add an extra parameter to general relativity (known as the "cosmological constant") to describe "dark energy" observations via a kind of 'anti gravity'; although we still don't fully understand what that means, or whether it's a correct description. It's also unclear whether this would have anything to do with quantum theories (like the standard model). General relativity can explain "dark matter" observations by assuming there is more mass/matter than we can see (i.e. it's electrically neutral and doesn't interact with light). Since the standard model tries to describe all of the fundamental constituents of matter, and forces including electromagnetism (light), having nothing to say about such a seemingly large amount of stuff is a rather large discrepancy in the standard model. AFAIK the standard model also says that neutrinos have zero mass; yet we've observed them undergoing radioactive decay ("neutrino oscillation", where each sort of neutrino can decay into the others). Particles which decay require some amount of time to do so. Particles with zero mass always travel at the speed of light (like photons, and hypothetical gravitons) and hence don't experience any time passing (this sentence is a consequence of special relativity). So particles with zero mass can't decay, so neutrinos can't have zero mass. I don't think we've measured their mass very accurately yet; we know it's very small, but it cannot be zero.
Will_Parker 8y ago
> I honestly don't get the "No, not again". Could you elaborate? As the cosmologist Sean Carroll said in his podcast, particle physicists haven't really been surprised by an observation since the 1970s. Presumably many were hoping for a surprise.
asdfman123 8y ago
If I have a conversation with you and you agree with everything I say, I learn nothing. If we have a conversation and you reveal that my assumptions are wrong, I can go back, rethink everything, and come out with a stronger world view. Basically, this experiment didn't tell scientists anything they didn't already know, or didn't prove them wrong--which might lead to newer, more interesting models that reveal more about the universe.

ainar-g 8y ago

Does this increase the likeliness that we need a bigger collider to finally reach new physics?

jug 8y ago
I wonder if it’s harder to get funding for that. With the LHC they at least expected the Higgs boson. And hopes for super symmetry signs that seem to have failed to materialize. With only hand waving and hopes for hypotheses left, and ever increasing costs... :-/
- ISL 8y ago
  The easy ask now is for a precision electron-positron collider to study the Higgs itself. Lepton/anti-lepton colliders are as clean as an experiment can be, in stark contrast to hadron colliders, which are as clean as a car accident. With the improved understanding of the Higgs that we have now, an e+/e- machine can be custom-built to study it in great detail. The Higgs is the newest fundamental particle to physics, and the first/only known scalar. We should expect that it has more to tell us than simply its own existence. Even when the LHC was being planned, LHC was the discovery machine, and precision experiments were to follow. In my opinion, only when those measurements are complete should we consider a huge leap toward higher energy, unless new accelerator technology emerges.
  - wolfgke 8y ago
    > The Higgs is the newest fundamental particle to physics, and the first/only known scalar. A question to physicists: Is there (strong) evidence that there might exist other scalars (if yes: at which energy level?). If not: Do there exist attempts of theories that predict why there is only one scalar?
    - ISL 8y ago
      I'm unaware of a particular compelling argument for another scalar. Scalars are easier for theorists to use when trying out a new theory, so they abound in theoretical physics. At some level, it is something of a surprise to have found that there is just one particle responsible for the Higgs mechanism, and it is indeed spin-0, as Nature hasn't given us one of those before. Prior to the discovery of the Higgs, perhaps the majority of physicists were betting on something Higgs-like, but not quite the pure vanilla Standard Model Higgs. I would not bet any money on it, but if one were looking for another scalar, one might find it in whatever mechanism underlies dark energy. Many theoretical models for dark energy use scalars, again, because they are easier...

delhanty 8y ago

Sorry, I don't understand this point. If a model of the universe was completely correct, wouldn't it have equivalent complexity to the universe and hence not be a model?

jon_richards 8y ago
No? Think of the game of life. Low model complexity, high universe complexity.
- deleted 8y ago
  [deleted]
- digi_owl 8y ago
  I think the term used is emergent complexity. So when you go from particle physics to chemistry, new complexities emerge that can't be explained in the realm of particle physics alone (iirc). sadly certain "sciences" still cling to the idea that they can simply aggregate the results from multiple of their "particles" and get a solution for larger systems.
  - xoa 8y ago
    >So when you go from particle physics to chemistry, new complexities emerge that can't be explained in the realm of particle physics alone (iirc). Correct me if I'm misunderstanding, but I think you're confusing general theory vs practical applicable models here maybe? Yes, fundamental principles of interaction can combine at scale to create new large scale effects, but that doesn't change the fact that they came out of fundamental principles nor that they can't be "explained" via those principles. There is no magic that pops into existence up the chain. The asymmetry of water molecules and the way their electron clouds distribute create all sorts of fascinating effects in bulk water, but they're still directly coming out of physics of course. The issue in practice however is that the level of computing necessary to accurately model reality at scale from fundamentals matches or exceeds actually doing it in reality, and for us rapidly becomes absolutely, utterly infeasible for anything but the simplest systems. "New emergent complexities" absolutely "can be explained" from a correct lower level set of principles, but that doesn't mean we can actually crunch the math at any scale we want. So we need higher level bulk models too, at many levels all the way up, which are good enough to be effective approximations to a given level of accuracy in practical computing time. The low level fundamentals often at bulk average out due to random variance in sufficient quantity and are irrelevant to whatever we care about, so there is no need to do it that expensively (even if we could). But that isn't the same thing as the fundamentals being wrong somehow or not being at the root of everything above.

dukwon 8y ago

> within the current precision of the measurement The error bars are ±20%, so there's quite a lot of wiggle room for new physics.

f137 8y ago

Well, the standard model can be correct. It is correct until some experiment proves otherwise. It is full of unexplained hadcoded parameters, indeed, which need an explanation from outside of the SM.

westurner 8y ago
> It is full of unexplained hadcoded parameters, indeed, which need an explanation from outside of the SM. https://en.wikipedia.org/wiki/Magic_number_(programming)#Unnamed_numerical_constants https://en.wikipedia.org/wiki/Magic_number_(programming)#Unn... > The term magic number or magic constant refers to the anti-pattern of using numbers directly in source code
- bradleyjg 8y ago
  Who is going to request changes when doing a code review on a pull request from God?
  - adrianratnapala 8y ago
    God doesn't use GitHub. You have to run `git format-patch` and email the results to Him.
    - eloff 8y ago
      Yeah him and Torvalds alike, maybe it's an ego thing. Or a graybeard thing?
  - dylan604 8y ago
    But which branch do you pull from? God has been forked so many times, it's hard to keep track. There are several distros available, so I guess you just get to pick the one that checks the most of your needs at the time.
dwaltrip 8y ago
The standard model has no conception of gravity, so it is most certainly incomplete, at the very least.

etatoby 8y ago

I've been told by a physicist friend of mine that one of the big problems is the amount of data produced by LHC sensor arrays. While the LHC is running, 600,000,000 particle collisions happen every second. Every collision produces particles that decay in complex ways into more particles, and so on. I forgot the numbers, but they have severals layers of filtering between sensors and long-term storage. First there are FPGA-based real-time filters, next to the sensors, which throw away most of the data as "noise." Then there are local CPUs which throw away most of the remaining data, again classified as "noise" or uninteresting. Finally, what remains (30,000 TB/year) is stored long-term to be later analyzed by physicists. All levels of filtering and analysis, from the FPGA to the physicist's algorithms, make use of the Standard Model itself and the rest of known physics to figure out what's "interesting" and what's "noise." One big problem is thus: how can we find new things if we are only looking for what we already know? Hence the need for machine learning and automatic pattern discovery.