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Sometimes I feel that people writing about physics are having great fun with deliberately confusing people by making stuff sound magical and illogical. This pa

Sometimes I feel that people writing about physics are having great fun with deliberately confusing people by making stuff sound magical and illogical. This particular effect has nothing to do with whether or not anyone is looking at an object. It's the methods of making it visible that cause the effect.

gus_massa 11y ago
I agree. I think that a big part of the problem is trying to make the new more layman friendly removing all the math. Quantum mechanics is unintuitive but the math is very clear, so "anyone" can get the same correct result for an experiment. When you remove the math, you keep only the unintuitive part. Another part of the problem is linkbait, making slightly wrong interpretations make more interesting articles. Sometimes there are a few articles from different news sites about some subject, and it's very common that the more misleading gets more attention here. Sadly, my rule of thumb is https://xkcd.com/1240/ https://xkcd.com/1240/ For an interesting explanation of what is happening here, I like the stack of slightly rotated polarizers. (See this comment https://news.ycombinator.com/item?id=10437289 https://news.ycombinator.com/item?id=10437289 ) The math is equivalent, but the result is not linkbaity. You can even try it at home! If you think enough about it, it's completely weird, but the calculation are pretty straightforward.
DyslexicAtheist 11y ago
could swear I've had some debugging / system testing sessions where the effect of me looking into it changed its state :-)
- rybosome 11y ago
  We call those "heisenbugs" - one of the most terrifying and maddening things you can encounter prior to a launch. I'm almost positive that I remember reading a sort from a game dev who ran into one of these right before a release, where printing some variable caused it to have the correct value; in this case, it was left in the game.
  - EwanG 11y ago
    Well, I know that I ran into a situation (and may once have posted about it) in a C program where I was doing printf to debug a program, and it ran fine. Whenever I removed them, the program would crash. Finally discovered that the printf debugging was forcing garbage collection which took care of a bad pointer somewhere else in the program. Honestly can't remember if I ever found the pointer or just left the printfs in the code...
    - nitrogen 11y ago
      Thank goodness we have Valgrind these days. Though I don't know how well it would handle a C app with a garbage collector. Calling printf can (will) change what's beyond the stack of the calling function, so if the pointer in question pointed outside the active stack, printf may have put a safer value there by coincidence.
  - backlava 11y ago
    There's the related example of the segfault termination message that was changed in a hex editor to "thank you for playing!" Wing Commander, maybe.
    - knodi123 11y ago
      That's a classic!
  - justifier 11y ago
    any language with mutable values will drive an unwarned mind insane methods of disassociating mutable objects before printing will save you from some heisenbugs a la javascript console.log(JSON.parse(JSON.stringify(obj))
- knodi123 11y ago
  This happens all the time. I very recently had an issue where a deadlock was fixed by a print statement, because two lists were being lazily evaluated at the same time, and the print statement forced one of the lists to be evaluated earlier and finished by the time the deadlock was occurring.
rottyguy 11y ago
When I was in highschool, I thought the same when opening up a Calculus book. Now, it's looking at stl code :-)
- TillE 11y ago
  I do remember a data structures textbook in university that actually managed to confuse me about stuff I already understood really well. It wasn't offering a different perspective, it was just that badly written.
Benichmt1 11y ago
I thought the same thing when someone showed me the popular "Dr. Quantum" double slit video (https://www.youtube.com/watch?v=DfPeprQ7oGc https://www.youtube.com/watch?v=DfPeprQ7oGc). Generally a decent layman's explanation of the experiment, but they had to conflate quantum mechanics with magic by saying "the atom knew it was being watched..." It's very hard to handle these misconceptions once they're already so widespread.
trevelyan 11y ago
Please explain?
- gnaritas 11y ago
  Atoms don't know they're being watched and using language like watched misleads people into thinking they do. Same issue as the double slit experiment. Watching is not passive, the correct term should be measured and the methods of measuring things affects them because you have to bounce particles off of things to measure them and thus measuring them (watching) changes their behavior.
  - criddell 11y ago
    Is it possible to measure with multiple devices that cancel each other out and get back to the same behavior as the unobserved system?
    - gnaritas 11y ago
      They actually are coming up with crazy ways to indirectly obtain measurement without interference or at least less, but this is about the limits of my knowledge on the subject.
- recycleme 11y ago
  Basically, this is called the observer effect. The process of observing something can change the thing you are observing. https://en.wikipedia.org/wiki/Observer_effect_(physics) https://en.wikipedia.org/wiki/Observer_effect_(physics)
arrel 11y ago
A better title might be "Scientists pause the motion of atoms by blasting them with an imaging laser"
- acqq 11y ago
  "Atoms cooled near absolute zero don't move while beamed with the laser"
grokys 11y ago
I think this video is a good explanation you can use to refer to people with that misunderstanding: https://www.youtube.com/watch?v=sQfSm6o-KlQ https://www.youtube.com/watch?v=sQfSm6o-KlQ (Assuming it's correct - I'm not physicist)
- Strilanc 11y ago
  The main problem with that series of videos, if I remember correctly, is that it only ever gives high-level descriptions of experiment outcomes. Those are interesting, but they aren't really good explanations. Then to top that off, they get some of the important details wrong. For example, in the quantum eraser video referred to by the video you linked, it's said that there's an interference pattern for B when you don't measure the entangled associated photon A (and that there is one when you do measure A). That's not the case. If it was the case, we'd have a handy-dandy FTL communication mechanism. What actually happens is that there's never a visible interference pattern for B in this experiment. Instead, you use the measurements of A to filter or split the measurements of B into two groups (e.g. Bs when A up, Bs when A down). Within each group of measurements, you'll find an interference pattern. The two interference patterns will complement each other so the sum is an apparent lack-of-interference; you need the As to do the separation. I personally think the the quantum eraser experiment has a terrible misleading name. It's more of a "use entangled measurements to find the interference" experiment.
Dylan16807 11y ago
But it doesn't matter what method you use. Anything that checks the position rapidly will keep it from moving.

gus_massa 11y ago

I agree. I think that a big part of the problem is trying to make the new more layman friendly removing all the math. Quantum mechanics is unintuitive but the math is very clear, so "anyone" can get the same correct result for an experiment. When you remove the math, you keep only the unintuitive part. Another part of the problem is linkbait, making slightly wrong interpretations make more interesting articles. Sometimes there are a few articles from different news sites about some subject, and it's very common that the more misleading gets more attention here. Sadly, my rule of thumb is https://xkcd.com/1240/ https://xkcd.com/1240/ For an interesting explanation of what is happening here, I like the stack of slightly rotated polarizers. (See this comment https://news.ycombinator.com/item?id=10437289 https://news.ycombinator.com/item?id=10437289 ) The math is equivalent, but the result is not linkbaity. You can even try it at home! If you think enough about it, it's completely weird, but the calculation are pretty straightforward.

DyslexicAtheist 11y ago

could swear I've had some debugging / system testing sessions where the effect of me looking into it changed its state :-)

rybosome 11y ago
We call those "heisenbugs" - one of the most terrifying and maddening things you can encounter prior to a launch. I'm almost positive that I remember reading a sort from a game dev who ran into one of these right before a release, where printing some variable caused it to have the correct value; in this case, it was left in the game.
- EwanG 11y ago
  Well, I know that I ran into a situation (and may once have posted about it) in a C program where I was doing printf to debug a program, and it ran fine. Whenever I removed them, the program would crash. Finally discovered that the printf debugging was forcing garbage collection which took care of a bad pointer somewhere else in the program. Honestly can't remember if I ever found the pointer or just left the printfs in the code...
  - nitrogen 11y ago
    Thank goodness we have Valgrind these days. Though I don't know how well it would handle a C app with a garbage collector. Calling printf can (will) change what's beyond the stack of the calling function, so if the pointer in question pointed outside the active stack, printf may have put a safer value there by coincidence.
- backlava 11y ago
  There's the related example of the segfault termination message that was changed in a hex editor to "thank you for playing!" Wing Commander, maybe.
  - knodi123 11y ago
    That's a classic!
- justifier 11y ago
  any language with mutable values will drive an unwarned mind insane methods of disassociating mutable objects before printing will save you from some heisenbugs a la javascript console.log(JSON.parse(JSON.stringify(obj))
knodi123 11y ago
This happens all the time. I very recently had an issue where a deadlock was fixed by a print statement, because two lists were being lazily evaluated at the same time, and the print statement forced one of the lists to be evaluated earlier and finished by the time the deadlock was occurring.

rottyguy 11y ago

When I was in highschool, I thought the same when opening up a Calculus book. Now, it's looking at stl code :-)

TillE 11y ago
I do remember a data structures textbook in university that actually managed to confuse me about stuff I already understood really well. It wasn't offering a different perspective, it was just that badly written.

Benichmt1 11y ago

I thought the same thing when someone showed me the popular "Dr. Quantum" double slit video (https://www.youtube.com/watch?v=DfPeprQ7oGc https://www.youtube.com/watch?v=DfPeprQ7oGc). Generally a decent layman's explanation of the experiment, but they had to conflate quantum mechanics with magic by saying "the atom knew it was being watched..." It's very hard to handle these misconceptions once they're already so widespread.

trevelyan 11y ago

Please explain?

gnaritas 11y ago
Atoms don't know they're being watched and using language like watched misleads people into thinking they do. Same issue as the double slit experiment. Watching is not passive, the correct term should be measured and the methods of measuring things affects them because you have to bounce particles off of things to measure them and thus measuring them (watching) changes their behavior.
- criddell 11y ago
  Is it possible to measure with multiple devices that cancel each other out and get back to the same behavior as the unobserved system?
  - gnaritas 11y ago
    They actually are coming up with crazy ways to indirectly obtain measurement without interference or at least less, but this is about the limits of my knowledge on the subject.
recycleme 11y ago
Basically, this is called the observer effect. The process of observing something can change the thing you are observing. https://en.wikipedia.org/wiki/Observer_effect_(physics) https://en.wikipedia.org/wiki/Observer_effect_(physics)

arrel 11y ago

A better title might be "Scientists pause the motion of atoms by blasting them with an imaging laser"

acqq 11y ago
"Atoms cooled near absolute zero don't move while beamed with the laser"

grokys 11y ago

I think this video is a good explanation you can use to refer to people with that misunderstanding: https://www.youtube.com/watch?v=sQfSm6o-KlQ https://www.youtube.com/watch?v=sQfSm6o-KlQ (Assuming it's correct - I'm not physicist)

Strilanc 11y ago
The main problem with that series of videos, if I remember correctly, is that it only ever gives high-level descriptions of experiment outcomes. Those are interesting, but they aren't really good explanations. Then to top that off, they get some of the important details wrong. For example, in the quantum eraser video referred to by the video you linked, it's said that there's an interference pattern for B when you don't measure the entangled associated photon A (and that there is one when you do measure A). That's not the case. If it was the case, we'd have a handy-dandy FTL communication mechanism. What actually happens is that there's never a visible interference pattern for B in this experiment. Instead, you use the measurements of A to filter or split the measurements of B into two groups (e.g. Bs when A up, Bs when A down). Within each group of measurements, you'll find an interference pattern. The two interference patterns will complement each other so the sum is an apparent lack-of-interference; you need the As to do the separation. I personally think the the quantum eraser experiment has a terrible misleading name. It's more of a "use entangled measurements to find the interference" experiment.

Dylan16807 11y ago

But it doesn't matter what method you use. Anything that checks the position rapidly will keep it from moving.