30 ms·

Gravity is unlikely to be the cause of quantum collapse, experiment suggests

127 points by tdhttt 6y ago

tdhttt 6y ago
The [paper](https://www.nature.com/articles/s41567-020-1008-4 https://www.nature.com/articles/s41567-020-1008-4)
corey_moncure 6y ago
Lazy evaluation.
- CamperBob2 6y ago
  https://en.wikipedia.org/wiki/Potentially_visible_set https://en.wikipedia.org/wiki/Potentially_visible_set
- jng 6y ago
  indeed :)
- brianberns 6y ago
  It does seem like some aspects of QM point to reality being simulation that tries to avoid the expense of unnecessary calculations.
  - Gene_Parmesan 6y ago
    QM-as-RNG for a simulated universe has been one of my favorite "for fun" pet theories over the years. Finding whether the electron went through slit A or slit B during the double-slit interference tests just feels a bit too much like running a Monte Carlo sim to me. I know it's just my human brain really trying to find an explanation that makes rational sense but it's a fun thought experiment. I mean, quantum fluctuations during inflationary expansion are (in my understanding) what's responsible for the tiny differences in mass distribution that led to the eventual formation of gas clouds/stars/galaxies. The negative gravity during expansion worked to keep the matter in an extremely low-entropy (highly ordered) state, but those unfathomably small quantum fluctuations were blown up by the same unfathomably massive proportions as everything else. Universe needed that RNG.
  - AgentME 6y ago
    There's no work QM is saving: it doesn't delay work or get to do less until when you physically look at something and then get to skip work for things you don't look at. * Things that are in superposition would require more computation for all their many alternate versions (most of which aren't meaningfully interacted with), not less, and the extra work for managing superpositions continues forever if MWI is right. All particles are constantly entering new superpositions, not just individual particles in fancy lab experiments. Only the very simplest of particle interactions (like two individual hydrogen atoms interacting) are feasible to simulate with full quantum mechanics on classical computers. * "Observation" happens through any physical interaction at all, including particle collisions. Outside of some individual particles inside carefully controlled experiments, most particles end up transitively interacting with most other particles near them. If the universe was at all optimized for simulation costs for human experience, we probably wouldn't expect there to be be trillions of galaxies with hundreds of millions of stars each, for the smallest particles to be on the scale of billion-billionths compared to humans, or for QM to work anything like it does.
    - saalweachter 6y ago
      That time-steps for atomic interactions need to be picoseconds or smaller, but interesting biological reactions take minutes+ [eg,protein folding] is also a PITA.
- im3w1l 6y ago
  Quantum computers are asymptotically more powerful than classical computers. This means that our world is actually harder to simulate (rather than easier as you seem to suggest) than a classical world would be.
akvadrako 6y ago
Gravity was never a leading explanation for collapse; it was always a fringe idea. Gravity is local and apparent collapse is non-local; it doesn’t even pass the smell test.
- trenchgun 6y ago
  The first paragraph seems to be pretty much all misleading or wrong: It’s one of the oddest tenets of quantum theory: a particle can be in two places at once—yet we only ever see it here or there. Textbooks state that the act of observing the particle “collapses” it, such that it appears at random in only one of its two locations. But physicists quarrel over why that would happen, if indeed it does. Now, one of the most plausible mechanisms for quantum collapse—gravity—has suffered a setback.
  - ksaj 6y ago
    As soon as it says "here or there" the writer is clearly trying to make it binary again. It isn't "here or there" but a function of probability between those two "places." It's an infinite number of possible "locations," but we narrow it down to a large number of decimal places because otherwise we wouldn't be able to make use of it at all. If things were as written here, you could do all quantum calculations with a straight up coin toss (although some might argue that can with an adequately tiny coin, but that still only gets at the most basic understanding of "spin" and only becomes an accurate analogy if the coin is flipped randomly in zero-g). Our higher level concept of gravity (at least in the classical sense) has been known to break down to the point that it doesn't apply to quantum mechanics for quite a long time now. The writer should just google "quantum gravity" to discover what a complicated subject that becomes.
    - trenchgun 6y ago
      Indeed. The weird thing is that the writer of that article has apparently written a popular science book about quantum mechanics too: https://us.macmillan.com/books/9780374536619 https://us.macmillan.com/books/9780374536619
Animats 6y ago
Nice. It's an actual experimental result.
zackees 6y ago
Tesla was right about Einstein. He was a fuzzy hair crackpot and his mathematical model for the Universe is riddled with contradictions yet the media continually pushes this guy. Why? It's funny how science is portrayed as careful and thoughtful but then the main stream media pushes theories like string theory and super symmetry, which fall to pieces as soon as the large particle accelerator machines came online. When are we going to declare particle physics as fundamentally broken and start over at N. Tesla?
- CodesInChaos 6y ago
  Which model do you prefer? Both special and general relativity are clearly much better models of reality that Newtonian physics, even if they break down under extreme conditions. You're right that string theory and super symmetry are dubious, but it's not like they're anywhere close to being accepted.
- eitland 6y ago
  > Tesla was right about Einstein. He was a fuzzy hair crackpot and his mathematical model for the Universe is riddled with contradictions yet the media continually pushes this guy. Why? Why? Because it works for a lot of stuff. Example: We wouldn't have working GPS without. But let me admit that if you have a better model I'm all for that.
mrwnmonm 6y ago
I read it "Gravity is unlucky"
- mrwnmonm 6y ago
  Why in the hell I get downvoted for this comment? The world is full of freaks.
TheRealPomax 6y ago
"Now, one of the most plausible mechanisms for quantum collapse—gravity—has suffered a setback." no it hasn't: stop trying to inject drama where there is none.
wwarner 6y ago
I don't understand why we would think wave-function collapse would release radiation.
deleted 6y ago
[deleted]
mgraczyk 6y ago
What percentage of practicing physicists actually think there is something "missing" in the quantum formalism as it relates to "wavefunction collapse"? I'm not a physicist, but from the few years of QM I took in college my take is that there is nothing special about "measurement", it's just a label we apply to certain states becoming entnagled. As long as you don't believe there is anything magical about humans or other "conscious" observers, then there doesn't seem to be anything to figure out about collapse.
- Xcelerate 6y ago
  > then there doesn't seem to be anything to figure out about collapse. Then why is quantum state evolution seemingly continuous and unitary some of the time, and sharply discontinuous at other times?
  - im3w1l 6y ago
    It seems continuous and unitary when the experimenter takes a lot of care to create a simple and very isolated system. When it's brought into contact with the mess that is the rest of the world it changes character very quickly, and interactions with the rest of the world completely swamp the internal dynamics.
- fsh 6y ago
  In the lab we do measure things and we do observe wavefunction collapse. There is no satisfying explanation why "us becoming entangled with the quantum system" or whatever explanation one chooses looks like collapse to us.
  - mgraczyk 6y ago
    I've always been content to know that after measurement, the quantum system that includes both me and the device has a certain quantum state which is a superposition of all the measurement eigenstates, but by construction that state couldn't be measured in such a way that I would have ever experienced an inconsistency.
- 6y ago
amai 6y ago
Every measurement (gravitational, electronic, magnetic etc. ) causes a collapse of the probabilities. This has nothing to do with quantum mechanics. This is simply statistics/math and has nothing to do with physics. A simple example: As long as one doesn't look at a coin, the probability that it shows head or tail is 50%. After the measurement it "collapses" to 100% for one of the options. But the "collapse" is only a mathematical "collapse", not a physical one. Physics only limits how precise and fast your measurement apparatus can be.

127 points by tdhttt 6y ago

tdhttt 6y ago

The [paper](https://www.nature.com/articles/s41567-020-1008-4 https://www.nature.com/articles/s41567-020-1008-4)

corey_moncure 6y ago

Lazy evaluation.

CamperBob2 6y ago
https://en.wikipedia.org/wiki/Potentially_visible_set https://en.wikipedia.org/wiki/Potentially_visible_set
jng 6y ago
indeed :)
brianberns 6y ago
It does seem like some aspects of QM point to reality being simulation that tries to avoid the expense of unnecessary calculations.
- Gene_Parmesan 6y ago
  QM-as-RNG for a simulated universe has been one of my favorite "for fun" pet theories over the years. Finding whether the electron went through slit A or slit B during the double-slit interference tests just feels a bit too much like running a Monte Carlo sim to me. I know it's just my human brain really trying to find an explanation that makes rational sense but it's a fun thought experiment. I mean, quantum fluctuations during inflationary expansion are (in my understanding) what's responsible for the tiny differences in mass distribution that led to the eventual formation of gas clouds/stars/galaxies. The negative gravity during expansion worked to keep the matter in an extremely low-entropy (highly ordered) state, but those unfathomably small quantum fluctuations were blown up by the same unfathomably massive proportions as everything else. Universe needed that RNG.
- AgentME 6y ago
  There's no work QM is saving: it doesn't delay work or get to do less until when you physically look at something and then get to skip work for things you don't look at. * Things that are in superposition would require more computation for all their many alternate versions (most of which aren't meaningfully interacted with), not less, and the extra work for managing superpositions continues forever if MWI is right. All particles are constantly entering new superpositions, not just individual particles in fancy lab experiments. Only the very simplest of particle interactions (like two individual hydrogen atoms interacting) are feasible to simulate with full quantum mechanics on classical computers. * "Observation" happens through any physical interaction at all, including particle collisions. Outside of some individual particles inside carefully controlled experiments, most particles end up transitively interacting with most other particles near them. If the universe was at all optimized for simulation costs for human experience, we probably wouldn't expect there to be be trillions of galaxies with hundreds of millions of stars each, for the smallest particles to be on the scale of billion-billionths compared to humans, or for QM to work anything like it does.
  - saalweachter 6y ago
    That time-steps for atomic interactions need to be picoseconds or smaller, but interesting biological reactions take minutes+ [eg,protein folding] is also a PITA.
im3w1l 6y ago
Quantum computers are asymptotically more powerful than classical computers. This means that our world is actually harder to simulate (rather than easier as you seem to suggest) than a classical world would be.

akvadrako 6y ago

Gravity was never a leading explanation for collapse; it was always a fringe idea. Gravity is local and apparent collapse is non-local; it doesn’t even pass the smell test.

trenchgun 6y ago
The first paragraph seems to be pretty much all misleading or wrong: It’s one of the oddest tenets of quantum theory: a particle can be in two places at once—yet we only ever see it here or there. Textbooks state that the act of observing the particle “collapses” it, such that it appears at random in only one of its two locations. But physicists quarrel over why that would happen, if indeed it does. Now, one of the most plausible mechanisms for quantum collapse—gravity—has suffered a setback.
- ksaj 6y ago
  As soon as it says "here or there" the writer is clearly trying to make it binary again. It isn't "here or there" but a function of probability between those two "places." It's an infinite number of possible "locations," but we narrow it down to a large number of decimal places because otherwise we wouldn't be able to make use of it at all. If things were as written here, you could do all quantum calculations with a straight up coin toss (although some might argue that can with an adequately tiny coin, but that still only gets at the most basic understanding of "spin" and only becomes an accurate analogy if the coin is flipped randomly in zero-g). Our higher level concept of gravity (at least in the classical sense) has been known to break down to the point that it doesn't apply to quantum mechanics for quite a long time now. The writer should just google "quantum gravity" to discover what a complicated subject that becomes.
  - trenchgun 6y ago
    Indeed. The weird thing is that the writer of that article has apparently written a popular science book about quantum mechanics too: https://us.macmillan.com/books/9780374536619 https://us.macmillan.com/books/9780374536619

Animats 6y ago

Nice. It's an actual experimental result.

zackees 6y ago

Tesla was right about Einstein. He was a fuzzy hair crackpot and his mathematical model for the Universe is riddled with contradictions yet the media continually pushes this guy. Why? It's funny how science is portrayed as careful and thoughtful but then the main stream media pushes theories like string theory and super symmetry, which fall to pieces as soon as the large particle accelerator machines came online. When are we going to declare particle physics as fundamentally broken and start over at N. Tesla?

CodesInChaos 6y ago
Which model do you prefer? Both special and general relativity are clearly much better models of reality that Newtonian physics, even if they break down under extreme conditions. You're right that string theory and super symmetry are dubious, but it's not like they're anywhere close to being accepted.
eitland 6y ago
> Tesla was right about Einstein. He was a fuzzy hair crackpot and his mathematical model for the Universe is riddled with contradictions yet the media continually pushes this guy. Why? Why? Because it works for a lot of stuff. Example: We wouldn't have working GPS without. But let me admit that if you have a better model I'm all for that.

mrwnmonm 6y ago

I read it "Gravity is unlucky"

mrwnmonm 6y ago
Why in the hell I get downvoted for this comment? The world is full of freaks.

TheRealPomax 6y ago

"Now, one of the most plausible mechanisms for quantum collapse—gravity—has suffered a setback." no it hasn't: stop trying to inject drama where there is none.

wwarner 6y ago

I don't understand why we would think wave-function collapse would release radiation.

deleted 6y ago

[deleted]

mgraczyk 6y ago

What percentage of practicing physicists actually think there is something "missing" in the quantum formalism as it relates to "wavefunction collapse"? I'm not a physicist, but from the few years of QM I took in college my take is that there is nothing special about "measurement", it's just a label we apply to certain states becoming entnagled. As long as you don't believe there is anything magical about humans or other "conscious" observers, then there doesn't seem to be anything to figure out about collapse.

Xcelerate 6y ago
> then there doesn't seem to be anything to figure out about collapse. Then why is quantum state evolution seemingly continuous and unitary some of the time, and sharply discontinuous at other times?
- im3w1l 6y ago
  It seems continuous and unitary when the experimenter takes a lot of care to create a simple and very isolated system. When it's brought into contact with the mess that is the rest of the world it changes character very quickly, and interactions with the rest of the world completely swamp the internal dynamics.
fsh 6y ago
In the lab we do measure things and we do observe wavefunction collapse. There is no satisfying explanation why "us becoming entangled with the quantum system" or whatever explanation one chooses looks like collapse to us.
- mgraczyk 6y ago
  I've always been content to know that after measurement, the quantum system that includes both me and the device has a certain quantum state which is a superposition of all the measurement eigenstates, but by construction that state couldn't be measured in such a way that I would have ever experienced an inconsistency.
6y ago

amai 6y ago

Every measurement (gravitational, electronic, magnetic etc. ) causes a collapse of the probabilities. This has nothing to do with quantum mechanics. This is simply statistics/math and has nothing to do with physics. A simple example: As long as one doesn't look at a coin, the probability that it shows head or tail is 50%. After the measurement it "collapses" to 100% for one of the options. But the "collapse" is only a mathematical "collapse", not a physical one. Physics only limits how precise and fast your measurement apparatus can be.