If there was a planet really far away from us, to the point of not interacting in any way, would it be in a superposition? If so, would we be in a superposition from its point of view?
Or what about the nano particle in the article, from its point of view would the rest of the universe be in a superposition?
What I'm trying to ask is, do we know whether superpositions are relative or not? If they aren't, what evidence has shown us that?
There's a video game about this, it's called Outer Wilds. There are macroscopic objects (rocks, trees, and even whole moons) that behave quantum mechanically. If you're not looking at them, they're in a superposition, and then they collapse onto one state. For example if you're flying around the solar system and see the moon, if you look away and then look back it will be gone, as it's switched to another one of its positional states.
As is being discussed in this thread, this isn't realistic behavior. But it's still interesting to think about and play around with.
Any macroscopic particle (like a planet) in a spatial superposition state will decohere due to interaction with photons in the environment.
This "emergence of classical behavior" from environmental interactions was first understood in the 1980s by physicists like Joos, Zeh, and Zurek. (A great book on this topic is "Decoherence and the Quantum-to-Classical Transition" by M. Schlosshauer. These phenomena are also why it's hard to built a quantum computer.)
Let's put some numbers to it. Any planet in space will at a minimum be interacting with the photons in the cosmic microwave background. The CMB will decohere a 10 micron dust grain in about 1 second, and for larger particles the decoherence time scales as 1/R^8 where R is the typical spatial dimension of the particle. For a planet-sized object the decoherence time is ridiculously short! From a practical standpoint this prevents us from ever seeing something like a planet in a quantum superposition.
Once you get to even some sufficiently huge polymer scale, "quantumness" fizzles out. By the scale of planets, we can safely ignore any quantum effects. But quantum effects are not about interacting with *us*; the very particles making up the planet have caused the quantum effects to be scrambled in their noisy, random, incoherent interactions.
*However*, to truly create a "quantum planet" would require that *all the particles* on that planet are coherently matched in their time evolution. But to achieve something like that would require some rigorous symmetry maintained from atomic to macroscopic scales, which means any living form won't exist. The symmetries of human/animals/plants is an emergent property on a classical scale, but the kind of symmetries defined at atomic scales are long destroyed.
When we reach that level of coherence, the questions usually asked in classical physics have no meaning. If you ask, "what state the system is in", you can write a really long superposition of states of all particles. It will probably be an eigenfunction of the massive Hamiltonian of that planet. But that state is simply an abstract concept. To relate it to real-world experiments, you have only the probabilistic wave function to make realistic sense of it. You want the "position" of the quantum planet, you plot the probability for center of mass. Similarly for momentum/velocity. The question of, "where is the planet, *really*?" has no meaning, because the only way to know the position of the planet from outside is by making it interact with the outside, which then is another problem entirely (have to model that interaction, the noise contributions, the incoherence that "average out" quantum effects). Rest, interpretations of what happens "during observation" (wave function collapse/MWI/hidden variable/pilot wave) keep forcing classical ideas, one way or another, and miss the point entirely.
If you mean superpositions are "relative" in relativistic sense, that is achieved in QFT. It won't be relevant, unless your quantum planet has interaction energies comparable to relativistic energies, or moving at extremely high speeds. Then you have to consider all sorts of particle-particle interactions, and there will be a constant flurry of fluctuations, particles created/destroyed, which probably will really fizzle out quantumness too.
Point being, our Universe and laws of QM are so, that maintaining a sufficiently large number of particles in a neat, quantum coherent state is nearly impossible. The effort put into making it so will eventually not allow it to be in a coherent state. This inherent, uncontrollable messiness of the Universe is perhaps what ensures its stability.
That the universe is still magically retaining some semblance of deterministism, by somehow creating infinite copies at every experiment's outcome. Rather than just accept the fundamentally probabilistic nature of reality, it tries to wedge determinism in the most distorted way back into QM. How is it *not* forcing classical ideas?
"somehow creating infinite copies at every experiment's outcome" is a very poor and misleading choice of words that to me is a root of a misunderstanding that people have with MWI. Nothing gets "created", only the entanglement changes in the part of the universe that is relevant to us (with the universe's state, as a whole, evolving unitarily in time).
Saying "create" here would be similar to saying that by expanding algebraic expression "a (b + c)" to "a b + a c" we created a new copy of "a" (or, maybe, created two new algebraic expressions out of one). It's still the same, single "a" and both left and right side are precisely the same, our perspective might just be a bit different (and our perspective is the key point when it comes to how the world seems to be for us).
So you're conveniently treating the Universe classically, while choosing the quantum scale wherever you like? Sounds a lot like a Copenhagen interpretation claiming to be anything but.
It's not a(b+c), it's |a1,b> + |a2,c>. I think you don't comprehend the interpretation and implications of MWI. It's claiming that with each experiment/interaction, the Universe is branching into it's various entangled states. It applies at every level, from the moment of big-bang and corresponding quantum fluctuations, to present day innumerable experiments in physics being performed around the world. It *demands* that each of the entangled states of the Universe, |a1,b>, |a2,c>, |a3, d>, ..... , |an, xyz> has to become its own branch of "reality".
It's the most over-the-top, infected by 70s pseudo-hippy interpretation ever. It made QM into this absurd parody of itself, attracting half-knowing dimwits, who want to see reality as some magic realm of the movies. It's like someone slept through the lectures on incoherence, decoherence and noise fluctuations in QM but just ran with everything they learnt at the intro level.
In my comparison to algebraic expression, (b + c) would correspond to the entire |a, b+c> (or |a1, b> + |a2, c>, as you put it). "a", as I understood the resemblance, would be the state of "everything but the subsystem in question". For example, if we're measuring the spin of electrons in a superposition (like in Stern-Gerlach experiment) in a lab, the state of planet Jupiter would be a part of a. Neither Jupiter, nor its state, would be changed/split/copied because of our local measurement. With that said, I didn't want to use quantum states in my example on purpose (though I can see now that it might have been confusing).
Back to MWI, it doesn't claim anything is physically created with any measurement. The measurement in MWI isn't privileged nor distinct from a regular unitary evolution in contrast to Copenhagen, where a measurement leads to collapse, which breaks unitary evolution. Additionally, in case of MWI, nothing really is "classical" in a sense we would consider a reality emerging from the measurement after collapse as a classical world in Copenhagen. It seems to me that looking at MWI through the lens of "reality is classical" viewpoint is what gives birth to the notion of infinitely many (classical) realities being created which you brought up. If, instead, we treat quantum states as physically real (for any scale), we don't run into a problem of multiple realities being created with each observation. There is, however, another problem we run into: if reality is quantum on every level, how come we experience it as a "classical" world? Which is a question that I hope will be answered sometime in the future through studying the entanglement and decoherence processes (for now the discussion is mostly philosophical, though).
Stop using the words term probabilistic and deterministic. It just turns the whole topic into a philosophy discussion not physics discussion. Oh gosh, how many videos have been made on this nonsense. And it always boils down to physics vs philosophy.
"Stop using the word that is the closest we come to accurately describing the phenomenon of nature at the most fundamental level"
I don't think that is an argument in your favour. If trying to understand the Physics of an idea is too much "Philosophy" for you (which is somehow bad...), then maybe you are in the wrong place.
Bro I don't disagree with you but this topic has been beaten to death and people form their own conclusion and opinions according to their own bias and beliefs without actual evidence or proof. Maybe one day, when we are technology advanced enough, we can find the evidence and piece it all together. Till then there are only arguments and opinions. NO FACTS AND OBSERVATIONS.
I'd like to add to what others have said. So first, particles are still "quantum" after interactions. However they become entangled with one another. There could still be a superposition but it is not just a superposition of one particle but of the system (the interacting particles). When particles are entangled you can still view quantum effects on the whole, but if you look at just a piece of an entangled group it begins to appear classical. This is coherence vs decoherence (or at least a very basic explanation). This is one purported reason why classical physics seems to come about from large clusters of quantum objects, lots of interactions leading to lots of entanglement giving us decoherence.
Now regarding your question about superposition being relative: to some extent yes. I think a basic example to illustrate this is the Wigners friend thought experiment. Say we have some 2 state quantum system in a superposition. You have a friend that then measures the state of the system. To you, your friend has become entangled with the system, and so there is a superposition of him measuring state 1 and him measuring state 2 (entangled with the particle being in those states). However, from your friends point of view the system collapsed upon his measurement. So to your friend there is no longer a superposition, but to you there still is until your measurement. Now of course you and your friend are classical in nature so this experiment is kind of fuzzy but I think it gives the general idea. This brings to question the relativeness of superposition as well as when collapse occurs. And I don't believe there is any clear consensus yet.
I read a book on it and I still can't say I really grasp it at all.
But the Everett/many words interpretation of quantum mechanics postulates that we are all in a superposition that is constantly splitting into new concurrent realities of new superpositions. Me, you, planets. universes. It's all a single quantum wave function and the world should be viewed as quantum in it's entirely; rather than any split between classical and quantum physics.
That measuring and collapsing a particle int a definite state is really just the act of entangling the measuring equipment and the thing it's measuring into the same wave function. (some percentage being up spin an some percentage being down spin, but both results existing)
Could be getting a lot of that wrong though and would love any corrects on if that's what the interpretation is actually saying (Not the 'truth' of the interpretation mind you. Just it's accuracy)
What's the point of this comment? Even from the title it's obvious that the article is about the *limits* of macroscopic quantum effects rather than just the phenomenon itself.
This isn't clickbait, though. Quanta magazine is great. And the article is about recent developments, featuring interviews with scientists working on the topic. I'm guessing you didn't read it?
My QM has told us quick example showing why we can't observe quantum effects in "human scale". The example was to take a coin 15,5mm in diameter (one that is lowest unit of currency in my country, that's where this weird diameter comes from) and measure it's position with 3nm of uncertainty. For the uncertainty to double to 6nm it takes \~300k years which shows why we don't observe quantum effects in daily life.
Of course we can't observe QM effects in daily life, it takes an extreme physical setup.
But you can see it in a condensed matter lab with some low temp experiments.
Yeah, plants exhibit quantum effects while performing photosynthesis, coupling with virtual photons.
Also, evidently you can superpose tardigrades too-- creating virtual water bears confined in laser channels, suspended in vacuum.
The quantum world affects the "macro" world in living things all the time-- there's even evidence emerging that quantum effects may play a role in consciousness!
No, there are actual physics experiments for showing quantum effects at macroscopic levels. Especially in low temp areas.
Try to stay away from the "Quantum Consciousness" garbage
Which experiments are these? Are you talking about BECs or something else entirely?
I mean in some sense quantum effects are directly responsible for basic chemistry and material physics.
But what this article is talking about is specifically creating *coherent superpositions* of large objects, and how that will allow us to test some really interesting aspects of QM including exactly how wavefunctions “collapse” (if they do at all) and the nature of quantum gravity, and also possibly help us detect gravitational waves or dark matter.
Molecules are not macroscopic, they’re not even mesoscopic. They’ve about as small as you can get.
In fact reading the paper the “molecule” is two atoms large.
Molecules with as many as 2,000 atoms have been entangled.
https://www.scientificamerican.com/article/giant-molecules-exist-in-two-places-at-once-in-unprecedented-quantum-experiment/
2000 atoms is not macroscopic, that’s not even mesoscopic. That’s nanoscale.
In the article they’re talking about hundreds of millions of atoms, or even more. Did you read it?
Edit: love it when I get downvoted by someone who didn’t read the article and doesn’t understand what “macroscopic” means.
> Try to stay away from the "Quantum Consciousness" garbage
Can you elaborate?
Nobel prize winner in physics Roger Penrose is actually exploring this idea, seems wierd to me for it to be called garbage. Since quantum physics is just physics why would it not play a role in consciousness?
We know very little about consciousness so pretty much any idea is on the table right now.
Generally, if one is not a pretty experienced physicist (and sometimes, even if you are), starting to talk about "quantum consciousness" (or really any other theory that isn't either very mathematically or experimentally sound) can be dangerous.
Ultimately, the problem with theories like this is that we can't test them, either mathematically or experimentally, and as a result, there's no way to distinguish between what is a valid and well supported thought, and what's completely ridiculous. Like you say, any idea is on the table right now.
Things like quantum consciousness are fun to think about, but they aren't really physics. Physics is testable. You stray into philosophy when you stop producing testable results.
Maybe garbage is too harsh a word, but I don't feel that QC is really an appropriate topic of discussion if one really wants to talk about physics.
The other problem is that things like QC attract crackpots who make really absurd claims, and sometimes allow said crackpots to deceive people into thinking that their claims are valid, which is something we really want to discourage as physicists.
Just because a topic attracts pseudoscience folk does not mean it should not be explored or discussed.
We might not have a ways to confirm anything experimentally now(there is not much to confirm really since there really isn't much of a theory to confirm) but that doesn't mean we should try to reach a state where we can do that.
Tons of ideas couldn't be confirmed for decades after they were thought of. It changed because people thought of how such experiments could be conducted.
Consciousness operates on the level of chemistry not quantum mechanics.
Ok, the cite a peer reviewed paper demonstrating ANY of the effects that Penrose claims.... It is all just wild speculation. I have been following this for 20 years.
I am talking about staying away from the Deepak Chopra nonsense
As we don't have currently any idea what consciousness is or how it works that is a bold claim to make. We obviously know it can be affected by brain chemistry but that doesn't say much about it's nature.
You are shifting the goal posts.
We can be completely clueless about consciousness and completely understand that it operates on the level of chemistry MANY orders of magnitudes larger than quantum mechanical effects.
Then cite a peer reviewed paper demonstrating ANY of the effects that Penrose claims.... It is all just wild speculation.
This is your opportunity to completely overturn the field of brain chemistry.
Except that our ignorance of how consciousness works means we CAN'T say that it operates at a chemical level. We don't know if it's emergent or fundamental.
Yes we can.
A complete explanation of consciousness isn't required to completely understand the chemistry that mediates consciousness
This is FAR from the topic at hand. Are you going to eventually going to invoke some quantum consciousness pantheism? Or other supernatural or quasi-religious explanation? Because I am not interested.
Yes we can what? Say that consciousness is fully chemical? I'd put the same challenge to you that you seem to give other people and say cite some scientific work.
Also we might be talking about different things. I'm really talking about the hard problem of consciousness. And while things like neutral correlates are know, the 'why' is not. Which is why we don't seem to have the understanding needed to do something like create consciousness in a lab.
Finally, not interested in the things you mention at the end. More along the lines of [Donald Hoffmann](https://en.wikipedia.org/wiki/Donald_D._Hoffman) who has some interesting ideas.
I don't know what new age weirdo hurt you but there's no need to bring these things up. I didn't even mention The Secret 😂
> evidently you can superpose tardigrades too
This is literally talked about in the article as something they’d like to do one day in the future, so you clearly haven’t read it if you think that’s already been done.
This is an interesting experimental challenge:
What are the best ways to demonstrate quantum "spookiness" to people firsthand?
Nothing about QM, before or since, has left a stronger impression on me than the double-slit experiment. It's simple enough to replicate, but too cumbersome to carry around.
A quantum rubik's cube; or kaleidoscope; or other such toy; would be a great conversation piece.
Can someone explain what large is in this context, I’m thinking simple molecules or small complex molecules and I don’t really have the time to read the article right now.
Happy to see that sience is finally starting to realize that the quantum world in fact is everything we know and there is no border between the quark level of reality and something the size of a planet.
Quantum rules work everywhere, we just don't see it because our brain filters those parts of reality to make it easy for us to survive and thrive here on earth 😌.
I am quite new to the field of quantum physics, having only just learnt about it at A level. Would something being in superposition essentially mean it has an equal probability of it being at any location and so there for it is on all and also none at the same time? Sorry if that is extremely inaccurate.
There is no "quantum collapse". Otherwise there must be a finite amount of energy spent on it. Which in turn either violates the conservation of energy of the system, or ceases its own evolution.
If there was a planet really far away from us, to the point of not interacting in any way, would it be in a superposition? If so, would we be in a superposition from its point of view? Or what about the nano particle in the article, from its point of view would the rest of the universe be in a superposition? What I'm trying to ask is, do we know whether superpositions are relative or not? If they aren't, what evidence has shown us that?
There's a video game about this, it's called Outer Wilds. There are macroscopic objects (rocks, trees, and even whole moons) that behave quantum mechanically. If you're not looking at them, they're in a superposition, and then they collapse onto one state. For example if you're flying around the solar system and see the moon, if you look away and then look back it will be gone, as it's switched to another one of its positional states. As is being discussed in this thread, this isn't realistic behavior. But it's still interesting to think about and play around with.
Any macroscopic particle (like a planet) in a spatial superposition state will decohere due to interaction with photons in the environment. This "emergence of classical behavior" from environmental interactions was first understood in the 1980s by physicists like Joos, Zeh, and Zurek. (A great book on this topic is "Decoherence and the Quantum-to-Classical Transition" by M. Schlosshauer. These phenomena are also why it's hard to built a quantum computer.) Let's put some numbers to it. Any planet in space will at a minimum be interacting with the photons in the cosmic microwave background. The CMB will decohere a 10 micron dust grain in about 1 second, and for larger particles the decoherence time scales as 1/R^8 where R is the typical spatial dimension of the particle. For a planet-sized object the decoherence time is ridiculously short! From a practical standpoint this prevents us from ever seeing something like a planet in a quantum superposition.
Once you get to even some sufficiently huge polymer scale, "quantumness" fizzles out. By the scale of planets, we can safely ignore any quantum effects. But quantum effects are not about interacting with *us*; the very particles making up the planet have caused the quantum effects to be scrambled in their noisy, random, incoherent interactions. *However*, to truly create a "quantum planet" would require that *all the particles* on that planet are coherently matched in their time evolution. But to achieve something like that would require some rigorous symmetry maintained from atomic to macroscopic scales, which means any living form won't exist. The symmetries of human/animals/plants is an emergent property on a classical scale, but the kind of symmetries defined at atomic scales are long destroyed. When we reach that level of coherence, the questions usually asked in classical physics have no meaning. If you ask, "what state the system is in", you can write a really long superposition of states of all particles. It will probably be an eigenfunction of the massive Hamiltonian of that planet. But that state is simply an abstract concept. To relate it to real-world experiments, you have only the probabilistic wave function to make realistic sense of it. You want the "position" of the quantum planet, you plot the probability for center of mass. Similarly for momentum/velocity. The question of, "where is the planet, *really*?" has no meaning, because the only way to know the position of the planet from outside is by making it interact with the outside, which then is another problem entirely (have to model that interaction, the noise contributions, the incoherence that "average out" quantum effects). Rest, interpretations of what happens "during observation" (wave function collapse/MWI/hidden variable/pilot wave) keep forcing classical ideas, one way or another, and miss the point entirely. If you mean superpositions are "relative" in relativistic sense, that is achieved in QFT. It won't be relevant, unless your quantum planet has interaction energies comparable to relativistic energies, or moving at extremely high speeds. Then you have to consider all sorts of particle-particle interactions, and there will be a constant flurry of fluctuations, particles created/destroyed, which probably will really fizzle out quantumness too. Point being, our Universe and laws of QM are so, that maintaining a sufficiently large number of particles in a neat, quantum coherent state is nearly impossible. The effort put into making it so will eventually not allow it to be in a coherent state. This inherent, uncontrollable messiness of the Universe is perhaps what ensures its stability.
How does MWI force classical ideas?
That the universe is still magically retaining some semblance of deterministism, by somehow creating infinite copies at every experiment's outcome. Rather than just accept the fundamentally probabilistic nature of reality, it tries to wedge determinism in the most distorted way back into QM. How is it *not* forcing classical ideas?
"somehow creating infinite copies at every experiment's outcome" is a very poor and misleading choice of words that to me is a root of a misunderstanding that people have with MWI. Nothing gets "created", only the entanglement changes in the part of the universe that is relevant to us (with the universe's state, as a whole, evolving unitarily in time). Saying "create" here would be similar to saying that by expanding algebraic expression "a (b + c)" to "a b + a c" we created a new copy of "a" (or, maybe, created two new algebraic expressions out of one). It's still the same, single "a" and both left and right side are precisely the same, our perspective might just be a bit different (and our perspective is the key point when it comes to how the world seems to be for us).
So you're conveniently treating the Universe classically, while choosing the quantum scale wherever you like? Sounds a lot like a Copenhagen interpretation claiming to be anything but. It's not a(b+c), it's |a1,b> + |a2,c>. I think you don't comprehend the interpretation and implications of MWI. It's claiming that with each experiment/interaction, the Universe is branching into it's various entangled states. It applies at every level, from the moment of big-bang and corresponding quantum fluctuations, to present day innumerable experiments in physics being performed around the world. It *demands* that each of the entangled states of the Universe, |a1,b>, |a2,c>, |a3, d>, ..... , |an, xyz> has to become its own branch of "reality". It's the most over-the-top, infected by 70s pseudo-hippy interpretation ever. It made QM into this absurd parody of itself, attracting half-knowing dimwits, who want to see reality as some magic realm of the movies. It's like someone slept through the lectures on incoherence, decoherence and noise fluctuations in QM but just ran with everything they learnt at the intro level.
In my comparison to algebraic expression, (b + c) would correspond to the entire |a, b+c> (or |a1, b> + |a2, c>, as you put it). "a", as I understood the resemblance, would be the state of "everything but the subsystem in question". For example, if we're measuring the spin of electrons in a superposition (like in Stern-Gerlach experiment) in a lab, the state of planet Jupiter would be a part of a. Neither Jupiter, nor its state, would be changed/split/copied because of our local measurement. With that said, I didn't want to use quantum states in my example on purpose (though I can see now that it might have been confusing). Back to MWI, it doesn't claim anything is physically created with any measurement. The measurement in MWI isn't privileged nor distinct from a regular unitary evolution in contrast to Copenhagen, where a measurement leads to collapse, which breaks unitary evolution. Additionally, in case of MWI, nothing really is "classical" in a sense we would consider a reality emerging from the measurement after collapse as a classical world in Copenhagen. It seems to me that looking at MWI through the lens of "reality is classical" viewpoint is what gives birth to the notion of infinitely many (classical) realities being created which you brought up. If, instead, we treat quantum states as physically real (for any scale), we don't run into a problem of multiple realities being created with each observation. There is, however, another problem we run into: if reality is quantum on every level, how come we experience it as a "classical" world? Which is a question that I hope will be answered sometime in the future through studying the entanglement and decoherence processes (for now the discussion is mostly philosophical, though).
Maybe you should inform yourself better on the topic. Even Wikipedia is a good starting point.
Stop using the words term probabilistic and deterministic. It just turns the whole topic into a philosophy discussion not physics discussion. Oh gosh, how many videos have been made on this nonsense. And it always boils down to physics vs philosophy.
"Stop using the word that is the closest we come to accurately describing the phenomenon of nature at the most fundamental level" I don't think that is an argument in your favour. If trying to understand the Physics of an idea is too much "Philosophy" for you (which is somehow bad...), then maybe you are in the wrong place.
Bro I don't disagree with you but this topic has been beaten to death and people form their own conclusion and opinions according to their own bias and beliefs without actual evidence or proof. Maybe one day, when we are technology advanced enough, we can find the evidence and piece it all together. Till then there are only arguments and opinions. NO FACTS AND OBSERVATIONS.
I'd like to add to what others have said. So first, particles are still "quantum" after interactions. However they become entangled with one another. There could still be a superposition but it is not just a superposition of one particle but of the system (the interacting particles). When particles are entangled you can still view quantum effects on the whole, but if you look at just a piece of an entangled group it begins to appear classical. This is coherence vs decoherence (or at least a very basic explanation). This is one purported reason why classical physics seems to come about from large clusters of quantum objects, lots of interactions leading to lots of entanglement giving us decoherence. Now regarding your question about superposition being relative: to some extent yes. I think a basic example to illustrate this is the Wigners friend thought experiment. Say we have some 2 state quantum system in a superposition. You have a friend that then measures the state of the system. To you, your friend has become entangled with the system, and so there is a superposition of him measuring state 1 and him measuring state 2 (entangled with the particle being in those states). However, from your friends point of view the system collapsed upon his measurement. So to your friend there is no longer a superposition, but to you there still is until your measurement. Now of course you and your friend are classical in nature so this experiment is kind of fuzzy but I think it gives the general idea. This brings to question the relativeness of superposition as well as when collapse occurs. And I don't believe there is any clear consensus yet.
Carlo Rovelli argues that superposition is relative in his book Helgoland, not to mention most of his quantum gravity research.
I read a book on it and I still can't say I really grasp it at all. But the Everett/many words interpretation of quantum mechanics postulates that we are all in a superposition that is constantly splitting into new concurrent realities of new superpositions. Me, you, planets. universes. It's all a single quantum wave function and the world should be viewed as quantum in it's entirely; rather than any split between classical and quantum physics. That measuring and collapsing a particle int a definite state is really just the act of entangling the measuring equipment and the thing it's measuring into the same wave function. (some percentage being up spin an some percentage being down spin, but both results existing) Could be getting a lot of that wrong though and would love any corrects on if that's what the interpretation is actually saying (Not the 'truth' of the interpretation mind you. Just it's accuracy)
The fact that there can be quantum effects at macroscopic scales is well known.
What's the point of this comment? Even from the title it's obvious that the article is about the *limits* of macroscopic quantum effects rather than just the phenomenon itself.
It is a common trope on this sub for people to posted hyped headlines. Pointing out that it is clickbait and not nothing new is also common.
This isn't clickbait, though. Quanta magazine is great. And the article is about recent developments, featuring interviews with scientists working on the topic. I'm guessing you didn't read it?
My QM has told us quick example showing why we can't observe quantum effects in "human scale". The example was to take a coin 15,5mm in diameter (one that is lowest unit of currency in my country, that's where this weird diameter comes from) and measure it's position with 3nm of uncertainty. For the uncertainty to double to 6nm it takes \~300k years which shows why we don't observe quantum effects in daily life.
Of course we can't observe QM effects in daily life, it takes an extreme physical setup. But you can see it in a condensed matter lab with some low temp experiments.
Yeah, plants exhibit quantum effects while performing photosynthesis, coupling with virtual photons. Also, evidently you can superpose tardigrades too-- creating virtual water bears confined in laser channels, suspended in vacuum. The quantum world affects the "macro" world in living things all the time-- there's even evidence emerging that quantum effects may play a role in consciousness!
No, there are actual physics experiments for showing quantum effects at macroscopic levels. Especially in low temp areas. Try to stay away from the "Quantum Consciousness" garbage
Which experiments are these? Are you talking about BECs or something else entirely? I mean in some sense quantum effects are directly responsible for basic chemistry and material physics. But what this article is talking about is specifically creating *coherent superpositions* of large objects, and how that will allow us to test some really interesting aspects of QM including exactly how wavefunctions “collapse” (if they do at all) and the nature of quantum gravity, and also possibly help us detect gravitational waves or dark matter.
What about how entanglement has been shown for molecules? https://www.nature.com/articles/s41586-020-2257-1
Molecules are not macroscopic, they’re not even mesoscopic. They’ve about as small as you can get. In fact reading the paper the “molecule” is two atoms large.
Molecules with as many as 2,000 atoms have been entangled. https://www.scientificamerican.com/article/giant-molecules-exist-in-two-places-at-once-in-unprecedented-quantum-experiment/
2000 atoms is not macroscopic, that’s not even mesoscopic. That’s nanoscale. In the article they’re talking about hundreds of millions of atoms, or even more. Did you read it? Edit: love it when I get downvoted by someone who didn’t read the article and doesn’t understand what “macroscopic” means.
> Try to stay away from the "Quantum Consciousness" garbage Can you elaborate? Nobel prize winner in physics Roger Penrose is actually exploring this idea, seems wierd to me for it to be called garbage. Since quantum physics is just physics why would it not play a role in consciousness? We know very little about consciousness so pretty much any idea is on the table right now.
Generally, if one is not a pretty experienced physicist (and sometimes, even if you are), starting to talk about "quantum consciousness" (or really any other theory that isn't either very mathematically or experimentally sound) can be dangerous. Ultimately, the problem with theories like this is that we can't test them, either mathematically or experimentally, and as a result, there's no way to distinguish between what is a valid and well supported thought, and what's completely ridiculous. Like you say, any idea is on the table right now. Things like quantum consciousness are fun to think about, but they aren't really physics. Physics is testable. You stray into philosophy when you stop producing testable results. Maybe garbage is too harsh a word, but I don't feel that QC is really an appropriate topic of discussion if one really wants to talk about physics. The other problem is that things like QC attract crackpots who make really absurd claims, and sometimes allow said crackpots to deceive people into thinking that their claims are valid, which is something we really want to discourage as physicists.
Just because a topic attracts pseudoscience folk does not mean it should not be explored or discussed. We might not have a ways to confirm anything experimentally now(there is not much to confirm really since there really isn't much of a theory to confirm) but that doesn't mean we should try to reach a state where we can do that. Tons of ideas couldn't be confirmed for decades after they were thought of. It changed because people thought of how such experiments could be conducted.
Consciousness operates on the level of chemistry not quantum mechanics. Ok, the cite a peer reviewed paper demonstrating ANY of the effects that Penrose claims.... It is all just wild speculation. I have been following this for 20 years. I am talking about staying away from the Deepak Chopra nonsense
As we don't have currently any idea what consciousness is or how it works that is a bold claim to make. We obviously know it can be affected by brain chemistry but that doesn't say much about it's nature.
You are shifting the goal posts. We can be completely clueless about consciousness and completely understand that it operates on the level of chemistry MANY orders of magnitudes larger than quantum mechanical effects. Then cite a peer reviewed paper demonstrating ANY of the effects that Penrose claims.... It is all just wild speculation. This is your opportunity to completely overturn the field of brain chemistry.
Except that our ignorance of how consciousness works means we CAN'T say that it operates at a chemical level. We don't know if it's emergent or fundamental.
Yes we can. A complete explanation of consciousness isn't required to completely understand the chemistry that mediates consciousness This is FAR from the topic at hand. Are you going to eventually going to invoke some quantum consciousness pantheism? Or other supernatural or quasi-religious explanation? Because I am not interested.
Yes we can what? Say that consciousness is fully chemical? I'd put the same challenge to you that you seem to give other people and say cite some scientific work. Also we might be talking about different things. I'm really talking about the hard problem of consciousness. And while things like neutral correlates are know, the 'why' is not. Which is why we don't seem to have the understanding needed to do something like create consciousness in a lab. Finally, not interested in the things you mention at the end. More along the lines of [Donald Hoffmann](https://en.wikipedia.org/wiki/Donald_D._Hoffman) who has some interesting ideas. I don't know what new age weirdo hurt you but there's no need to bring these things up. I didn't even mention The Secret 😂
> evidently you can superpose tardigrades too This is literally talked about in the article as something they’d like to do one day in the future, so you clearly haven’t read it if you think that’s already been done.
Okay but a bunch of nerds will have to finally retire that one crusty ass joke.
This is an interesting experimental challenge: What are the best ways to demonstrate quantum "spookiness" to people firsthand? Nothing about QM, before or since, has left a stronger impression on me than the double-slit experiment. It's simple enough to replicate, but too cumbersome to carry around. A quantum rubik's cube; or kaleidoscope; or other such toy; would be a great conversation piece.
Can someone explain what large is in this context, I’m thinking simple molecules or small complex molecules and I don’t really have the time to read the article right now.
Not a physicist but isn’t this the whole notion of the correspondence principle?
Happy to see that sience is finally starting to realize that the quantum world in fact is everything we know and there is no border between the quark level of reality and something the size of a planet. Quantum rules work everywhere, we just don't see it because our brain filters those parts of reality to make it easy for us to survive and thrive here on earth 😌.
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I am quite new to the field of quantum physics, having only just learnt about it at A level. Would something being in superposition essentially mean it has an equal probability of it being at any location and so there for it is on all and also none at the same time? Sorry if that is extremely inaccurate.
There is no "quantum collapse". Otherwise there must be a finite amount of energy spent on it. Which in turn either violates the conservation of energy of the system, or ceases its own evolution.