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> I have no doubt quantum physicists know what they are talking about but...I always think it is the kind of excuse a schoolkid would give their teachers for th

by Rayhem 3y ago

> I have no doubt quantum physicists know what they are talking about but...I always think it is the kind of excuse a schoolkid would give their teachers for their calculations being wrong. Just to emphasize how extreme this dichotomy is, not only is quantum mechanics correct (in that it's a predictive model), it's the most correct physical theory humans have ever devised in that the measurements there have more significant figures than anything else.

mcmoor 3y ago
It's interesting that semiconductor engineers have to directly wrestle with the magic that's quantum tunneling. This theory is really not just a theory.
- neuromanser 3y ago
  You mean it's not just a hypothesis. I would really, really expect users of this site to know the difference.
  - elpocko 3y ago
    What if they don't? Will they cease to be users of this site? What if they speak a lot more languages than you, just not perfectly? Does it even matter what you would expect?
  - deleted 3y ago
    [deleted]
  - andrewflnr 3y ago
    Users of this site who pay attention to how science is actually practiced, and not the oversimplified cartoon version they teach us in school, know that the boundary between a "theory" and a "hypothesis" is rather blurry. For instance, have you ever noticed how it's called "string theory" despite having no real evidence for it? Have you ever heard anyone, let alone a real scientist, complain about this nomenclature? Early theories and fleshed-out hypotheses overlap a lot. There's no sharp transition from one to the other.
    - infamouscow 3y ago
      I think it's important to draw a distinction between the formal and natural sciences. HN is overrepresented by folks with backgrounds in mathematics and computer science where using "theory" is correct, e.g., set theory. Bret Weinstein explained the distinction between a hypothesis and theory a few weeks ago on YOUR WELCOME. https://www.youtube.com/watch?v=ac4MnNrs6g4 https://www.youtube.com/watch?v=ac4MnNrs6g4
      - andrewflnr 3y ago
        I specifically cited an example in the natural sciences, specifically physics. IIRC chemistry and biology do similar shenanigans at times. Again, consider how you could possibly draw a sharp distinction when accumulation of evidence is so often a gradual process. I'll consider responding to the video if you give me a reasonable timeslice, but I'm not going to watch the whole hour.
    - snowwrestler 3y ago
      String theory is supported by a ton of evidence in that it can produce many predictions and hypotheses that match observed data. That’s why it’s called a “theory” and why people continue to study it. What’s missing is a test that would produce evidence that would allow us to distinguish between string theory and competing theories. But that’s not nearly the same thing as saying it has “no real evidence.”
      - philipswood 3y ago
        Correct me if I'm wrong, but string theory is still in the "it's so pretty and elegant is must be true kind of territory". Not only do they have no proof, most of the potential experimental confirmations are at energies so high they're effectively out of reach for the foreseeable near future.
        AppleBananaPie 3y ago
        I used to think this same thing but I went down a rabbit hole a few months ago listening to people very critical of string theory like angela collier, sabbine, eric weinstein, peter woit and some others on youtube. Yeah they all have their own quirks but after listening to their take on the history of string theory the common things are it hasn't produced anything but the major proponents of it always talk like it has and in some cases outright lie about things that it has contributed. I really like listening to brian greene and sean carroll but now when I listen to them, particularly in recent videos, it feels like there is much less substance to what they're actually saying string theory has done. But who knows! Maybe I'll learn something new and completely flip my world view again, I'm not a physicist by any stretch so have to rely on listening to experts :)
  - mcmoor 3y ago
    The (scientific) theory is really not just a (colloquial) theory
- julianeon 3y ago
  The other famous example is PET scanners, which actually use a form of antimatter: positrons (the antimatter counterpart of electrons).
  - hwillis 3y ago
    You don't even need that. The prediction he's referring to as most accurate is the magnetic moment of the electron, which is used in plain old MRIs. If we didn't have the quantum mechanical correction, all of our MRI images would be distorted. Only by a few pixels, but it'd be noticeable!
- tonyarkles 3y ago
  In some devices it's something they have to fight against. In others, like SSDs, it's the feature that makes them work! It's not just a theory and it's not just another flaw that we've got to work around, we've taken it from a theory and turned it into useful technology.
- sph 3y ago
  We used fire in our daily lives even before organic chemistry existed.
seeknotfind 3y ago
So many significant digits includes a level of self-consistency of the model, since we are assuming the model to some degree in order to measure it. Though in this case, it's not the calculations that are wrong, but the model, we hope is wrong. That is, a new perspective and a new way of thinking about things may reveal more. Of course, we are always fighting against the irreducible complexity camp. However, the fundamental lack of cohesion between quantum and relativistic theories demonstrates there is at least one big thing we are still doing wrong.
- hwillis 3y ago
  > So many significant digits includes a level of self-consistency of the model No, that's incorrect. The specific measurement -the most accurate scientific prediction humans have ever made, the anomalous magnetic moment- is only to 1 in 10 trillion. The magnetic moment (think moment of inertia) is the ratio of force from the magnetic field to the mass of the electron. You put an electron into a magnetic field, and it'll turn to face the field at a certain speed. If you stick the electron in a vacuum, it overshoots (because of rotational momentum) and ends up wobbling back and forth at a specific frequency. That's how MRIs work; they make a big magnetic field (stronger on one end) and then measure how many electrons are wobbling in different areas, since the electrons in high-strength fields wobble faster. Specifically, you expect the wobble to get ~2.8025 GHz (similar to a microwave oven) faster for every 1000 gauss (please, no jokes about teslas). It's very convenient to measure a difference in frequency, since you can just measure the drift over time. Because that frequency is relatively high it takes about 30 minutes for the frequency to drift off by a half-cycle and totally cancel out your reference. And it's super easy to get a reference frequency, too. It's just the charge of an electron divided by 2x the mass of an electron. Did you do this experiment in physics class? https://www.youtube.com/watch?v=Kcn2VgBNJjg https://www.youtube.com/watch?v=Kcn2VgBNJjg Then you measured the charge/mass ratio of an electron. A clock that's accurate to 1 in 10 trillion is also not a big deal, although unless you have an oscilloscope in your house its probably more accurate than any clock you own. Still, you can buy a better Phase Locked Loop for a couple bucks. If you just wanted to measure the difference, you don't need that much precision, though. The correction from quantum mechanics is pretty large, relatively speaking: ~0.16%. Even the next several digits are super easy, and it's only those last ones that you really need to bust out the liquid helium. Lawrence and Livingston made the first cyclotron out of literal junk: https://upload.wikimedia.org/wikipedia/commons/6/61/4-inch-cyclotron.jpg https://upload.wikimedia.org/wikipedia/commons/6/61/4-inch-c... And it really doesn't take much more than junk to get to that 0.16% accuracy that lets you see that a classical prediction of the electron is just VERY wrong. But if you listen to those wizards with the bongos, suddenly they're really, really right about what that difference is: https://en.wikipedia.org/wiki/Vertex_function https://en.wikipedia.org/wiki/Vertex_function
blackhaj7 3y ago
That’s awesome to hear. I totally back the scientists and wish I could understand it better but I always like to have a chuckle that the crazy sounding parts are just the scientists making up stuff
ronald_raygun 3y ago
Just because it’s quantitatively accurate doesn’t mean it’s “true”. Like a fun fact I like is the geocentrism was extremely accurate in terms of astronomical predictions when heliocentricism came about (it was actually more accurate for a while).
- alok-g 3y ago
  How do you define 'true'? If two theories are working very well with no experiment available to indicate right vs. wrong for them, Occam's Razor would be all we would have to make a choice. That however does not really make one of them truer than the other.

by Rayhem 3y ago

mcmoor 3y ago

It's interesting that semiconductor engineers have to directly wrestle with the magic that's quantum tunneling. This theory is really not just a theory.

neuromanser 3y ago
You mean it's not just a hypothesis. I would really, really expect users of this site to know the difference.
- elpocko 3y ago
  What if they don't? Will they cease to be users of this site? What if they speak a lot more languages than you, just not perfectly? Does it even matter what you would expect?
- deleted 3y ago
  [deleted]
- andrewflnr 3y ago
  Users of this site who pay attention to how science is actually practiced, and not the oversimplified cartoon version they teach us in school, know that the boundary between a "theory" and a "hypothesis" is rather blurry. For instance, have you ever noticed how it's called "string theory" despite having no real evidence for it? Have you ever heard anyone, let alone a real scientist, complain about this nomenclature? Early theories and fleshed-out hypotheses overlap a lot. There's no sharp transition from one to the other.
  - infamouscow 3y ago
    I think it's important to draw a distinction between the formal and natural sciences. HN is overrepresented by folks with backgrounds in mathematics and computer science where using "theory" is correct, e.g., set theory. Bret Weinstein explained the distinction between a hypothesis and theory a few weeks ago on YOUR WELCOME. https://www.youtube.com/watch?v=ac4MnNrs6g4 https://www.youtube.com/watch?v=ac4MnNrs6g4
    - andrewflnr 3y ago
      I specifically cited an example in the natural sciences, specifically physics. IIRC chemistry and biology do similar shenanigans at times. Again, consider how you could possibly draw a sharp distinction when accumulation of evidence is so often a gradual process. I'll consider responding to the video if you give me a reasonable timeslice, but I'm not going to watch the whole hour.
  - snowwrestler 3y ago
    String theory is supported by a ton of evidence in that it can produce many predictions and hypotheses that match observed data. That’s why it’s called a “theory” and why people continue to study it. What’s missing is a test that would produce evidence that would allow us to distinguish between string theory and competing theories. But that’s not nearly the same thing as saying it has “no real evidence.”
    - philipswood 3y ago
      Correct me if I'm wrong, but string theory is still in the "it's so pretty and elegant is must be true kind of territory". Not only do they have no proof, most of the potential experimental confirmations are at energies so high they're effectively out of reach for the foreseeable near future.
      - AppleBananaPie 3y ago
        I used to think this same thing but I went down a rabbit hole a few months ago listening to people very critical of string theory like angela collier, sabbine, eric weinstein, peter woit and some others on youtube. Yeah they all have their own quirks but after listening to their take on the history of string theory the common things are it hasn't produced anything but the major proponents of it always talk like it has and in some cases outright lie about things that it has contributed. I really like listening to brian greene and sean carroll but now when I listen to them, particularly in recent videos, it feels like there is much less substance to what they're actually saying string theory has done. But who knows! Maybe I'll learn something new and completely flip my world view again, I'm not a physicist by any stretch so have to rely on listening to experts :)
- mcmoor 3y ago
  The (scientific) theory is really not just a (colloquial) theory
julianeon 3y ago
The other famous example is PET scanners, which actually use a form of antimatter: positrons (the antimatter counterpart of electrons).
- hwillis 3y ago
  You don't even need that. The prediction he's referring to as most accurate is the magnetic moment of the electron, which is used in plain old MRIs. If we didn't have the quantum mechanical correction, all of our MRI images would be distorted. Only by a few pixels, but it'd be noticeable!
tonyarkles 3y ago
In some devices it's something they have to fight against. In others, like SSDs, it's the feature that makes them work! It's not just a theory and it's not just another flaw that we've got to work around, we've taken it from a theory and turned it into useful technology.
sph 3y ago
We used fire in our daily lives even before organic chemistry existed.

seeknotfind 3y ago

So many significant digits includes a level of self-consistency of the model, since we are assuming the model to some degree in order to measure it. Though in this case, it's not the calculations that are wrong, but the model, we hope is wrong. That is, a new perspective and a new way of thinking about things may reveal more. Of course, we are always fighting against the irreducible complexity camp. However, the fundamental lack of cohesion between quantum and relativistic theories demonstrates there is at least one big thing we are still doing wrong.

hwillis 3y ago
> So many significant digits includes a level of self-consistency of the model No, that's incorrect. The specific measurement -the most accurate scientific prediction humans have ever made, the anomalous magnetic moment- is only to 1 in 10 trillion. The magnetic moment (think moment of inertia) is the ratio of force from the magnetic field to the mass of the electron. You put an electron into a magnetic field, and it'll turn to face the field at a certain speed. If you stick the electron in a vacuum, it overshoots (because of rotational momentum) and ends up wobbling back and forth at a specific frequency. That's how MRIs work; they make a big magnetic field (stronger on one end) and then measure how many electrons are wobbling in different areas, since the electrons in high-strength fields wobble faster. Specifically, you expect the wobble to get ~2.8025 GHz (similar to a microwave oven) faster for every 1000 gauss (please, no jokes about teslas). It's very convenient to measure a difference in frequency, since you can just measure the drift over time. Because that frequency is relatively high it takes about 30 minutes for the frequency to drift off by a half-cycle and totally cancel out your reference. And it's super easy to get a reference frequency, too. It's just the charge of an electron divided by 2x the mass of an electron. Did you do this experiment in physics class? https://www.youtube.com/watch?v=Kcn2VgBNJjg https://www.youtube.com/watch?v=Kcn2VgBNJjg Then you measured the charge/mass ratio of an electron. A clock that's accurate to 1 in 10 trillion is also not a big deal, although unless you have an oscilloscope in your house its probably more accurate than any clock you own. Still, you can buy a better Phase Locked Loop for a couple bucks. If you just wanted to measure the difference, you don't need that much precision, though. The correction from quantum mechanics is pretty large, relatively speaking: ~0.16%. Even the next several digits are super easy, and it's only those last ones that you really need to bust out the liquid helium. Lawrence and Livingston made the first cyclotron out of literal junk: https://upload.wikimedia.org/wikipedia/commons/6/61/4-inch-cyclotron.jpg https://upload.wikimedia.org/wikipedia/commons/6/61/4-inch-c... And it really doesn't take much more than junk to get to that 0.16% accuracy that lets you see that a classical prediction of the electron is just VERY wrong. But if you listen to those wizards with the bongos, suddenly they're really, really right about what that difference is: https://en.wikipedia.org/wiki/Vertex_function https://en.wikipedia.org/wiki/Vertex_function

blackhaj7 3y ago

That’s awesome to hear. I totally back the scientists and wish I could understand it better but I always like to have a chuckle that the crazy sounding parts are just the scientists making up stuff

ronald_raygun 3y ago

Just because it’s quantitatively accurate doesn’t mean it’s “true”. Like a fun fact I like is the geocentrism was extremely accurate in terms of astronomical predictions when heliocentricism came about (it was actually more accurate for a while).

alok-g 3y ago
How do you define 'true'? If two theories are working very well with no experiment available to indicate right vs. wrong for them, Occam's Razor would be all we would have to make a choice. That however does not really make one of them truer than the other.