How to Make a Delicious Pizza at Home

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In summary: Viewing the interference pattern as revealing information about the particle's path is what collapses the wave function. It doesn't matter if you're the only one watching or not.
  • #1
quddusaliquddus
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the title says it all.
 
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  • #2
What is "it", the monkey or the electron? In any case observed effect doesn't depend on whether or not anyone is watching. The diffraction pattern will appear. I don't know if the monkey cares.
 
  • #3
The monkey would fling feces at the detector screen.
 
  • #4
dav2008 pretty much nailed the sequence of events.
 
  • #5
Assuming that "it" is the electron, it would behave the same way if would if you were watching it. What, you thought your were special?
 
  • #6
dav2008 said:
The monkey would fling feces at the detector screen.

Is that before or after it types the collected works of Shakespear?
 
  • #7
Parlyne said:
Is that before or after it types the collected works of Shakespear?
Well, it's in superposition with a monkey that already has.
 
  • #8
LOL ... thanks for the replies.
 
  • #9
Riiiiiight... laying aside all that, I think that the point is somewhat moot. To know what had happened, you'd have to observe the result post-fact. BAM! Suddenly the monkey is no longer the only observer. Hear that gurgling sound? That's the waveform collapsing.
 
  • #10
My understanding of the currently generally accepted reading of the Copenhagen Interpretation is that that there is nothing special about 'observation' as such, any interaction with the universe at large will collapse the wave function. So any sort of measurement will do it, whether it involves a human, a monkey, an aardvark or just a photon detecting screen.
 
  • #11
It depends on if the monkey can sign or not. If the monkey can't, the wave function collapses as usual. If it can, the wave function collapses and the monkey signs to you, asking what journal the ensuing paper should be presented to, and what order the authors will be listed in.
 
  • #12


i don't believe what mumeishi said is true... the delayed choice quantum eraser experiment shows that even after measurement, once the "information" is erased the interference pattern re-emerges... so the awareness of the information is in fact what collapses wave functions. the monkey question is quite significant then... i wonder if there has been an experiment to find out.
 
  • #13
shahzk said:
i don't believe what mumeishi said is true... the delayed choice quantum eraser experiment shows that even after measurement, once the "information" is erased the interference pattern re-emerges... so the awareness of the information is in fact what collapses wave functions. the monkey question is quite significant then... i wonder if there has been an experiment to find out.

So, you do a double slit experiment and see an interference pattern. Fine, you don't know which slit each photon passed through, all makes sense.
Now you add polarizers behind each slit, orthogonal to each other, and do the experiment again. Each photon can only pass through one slit so the interference pattern disappears. Do YOU know which slit each photon passed through? No, of course not. So why does the interference pattern disappear if you have no knowledge/awareness of the photons' paths?

Isn't this enough to show that consciousness/awareness has nothing to do with the experimental outcome?

Here's a site which explains the quantum eraser quite nicely http://www.mathblog.ellerman.org/2011/11/a-common-qm-fallacy/
 
  • #14


Joncon said:
So, you do a double slit experiment and see an interference pattern. Fine, you don't know which slit each photon passed through, all makes sense.
Now you add polarizers behind each slit, orthogonal to each other, and do the experiment again. Each photon can only pass through one slit so the interference pattern disappears. Do YOU know which slit each photon passed through? No, of course not. So why does the interference pattern disappear if you have no knowledge/awareness of the photons' paths?

The interference is still there. It is just hidden. When do you 'erasure of information', two fringes appear.
 
  • #15


From Paul Kwiat:
In my opinion, I think it would be appropriate to say that the particle *has* traveled both paths, at least to the extent that that would be the quantum mechanical description of the state after the slits. In particular, even if there are which-way detectors sitting by both the top and bottom slit, the passage of the photon through the slits—according to strict quantum mechanics—simply entangles the path of the particle with the state of those detectors.

Bruce Rosenblum is saying what is changed is an unobserved past. We never observed the interference before finding out which way the particle went, or 'erasured' the which-way information. Only if we erase the information and do the appropriate correlations do we see the fringe and anti-fringe.
 
  • #16


StevieTNZ said:
The interference is still there. It is just hidden. When do you 'erasure of information', two fringes appear.

I think you're talking about the quantum eraser experiment. I was talking about a standard double slit experiment - each particle can only pass through one slit and therefore can't interfere with itself.
 
  • #17


I don't get this argument: it's already been shown that something that supposedly has no consciousness, such as a simply machine, can collapse a wave function by means of measurement the same as any other measurement.
 
  • #18


"In quantum mechanics, the Heisenberg uncertainty principle states a fundamental limit on the accuracy with which certain pairs of physical properties of a particle, such as position and momentum, can be simultaneously known. In layman's terms, the more precisely one property is measured, the less precisely the other can be controlled, determined, or known."

"The uncertainty principle states a fundamental property of quantum systems, and is not a statement about the observational success of current technology."."



http://en.wikipedia.org/wiki/Uncertainty_principle



The verb "know" only refers to conscious activity. It's part of what mind is.
 
  • #19


questionpost said:
I don't get this argument: it's already been shown that something that supposedly has no consciousness, such as a simply machine, can collapse a wave function by means of measurement the same as any other measurement.
The reason there is still disagreement as to what constitutes measurement is that it makes no experimental difference according to quantum mechanics. The way QM works under the Copenhagen interpretation is that you have to split the world into two parts, the “observer” or measurement device, and the “observed” or the particles you’re measuring.

The measurement device is assumed to behave classically. The particles in the observed system are in a superposition of states described by the wave function which keeps evolving until it interacts with the classical measurement device. The question is where to draw the line. You could consider a photon to be the observed system and an atom to be the measuring device, but you can also consider the photon-and-atom system as in a superposition of states, and take a Geiger counter to be the measurement device. So there is this von-Neumann chain, going from elementary particles to Geiger counters to human beings, and we have to decide where to cut it off.

Von Neumann proved in his famous "Bible" of QM that regardless of where you cut the chain, you would get the same experimental results. But he argued that wherever you cut the chain you have things made out of particles on each side of the cut, so there’s no principled way to place the cut in the middle. So he decided that you should place the cut between the human mind and the human body, because he believed that the mind is non-physical. Hence "consciousness causes collapse" was born. Nowadays, the most popular view is decoherence, where there is no real collapse, it's just that when you have a large number of particles in the environment interacting with the system, the wave function becomes smeared out and looks like it has collapsed. So decoherence gives us a reasonable place to cut the chain, when the number of particles involved reaches a critical number so that interference effect become negligible.
 
  • #20


lugita15 said:
The reason there is still disagreement as to what constitutes measurement is that it makes no experimental difference according to quantum mechanics. The way QM works under the Copenhagen interpretation is that you have to split the world into two parts, the “observer” or measurement device, and the “observed” or the particles you’re measuring.

The measurement device is assumed to behave classically. The particles in the observed system are in a superposition of states described by the wave function which keeps evolving until it interacts with the classical measurement device. The question is where to draw the line. You could consider a photon to be the observed system and an atom to be the measuring device, but you can also consider the photon-and-atom system as in a superposition of states, and take a Geiger counter to be the measurement device. So there is this von-Neumann chain, going from elementary particles to Geiger counters to human beings, and we have to decide where to cut it off.

Von Neumann proved in his famous "Bible" of QM that regardless of where you cut the chain, you would get the same experimental results. But he argued that wherever you cut the chain you have things made out of particles on each side of the cut, so there’s no principled way to place the cut in the middle. So he decided that you should place the cut between the human mind and the human body, because he believed that the mind is non-physical. Hence "consciousness causes collapse" was born. Nowadays, the most popular view is decoherence, where there is no real collapse, it's just that when you have a large number of particles in the environment interacting with the system, the wave function becomes smeared out and looks like it has collapsed. So decoherence gives us a reasonable place to cut the chain, when the number of particles involved reaches a critical number so that interference effect become negligible.

Yeah, an atom *does* technically measure a photon if it absorbs it. You draw the line between measurement and no measurement. If it doesn't collapse it's wave function, it's not a measurement. So if you shine a photon through a prism and the prism doesn't absorb it, then what you get are two polarization angles, the atoms didn't absorb it, so it's still subject to superposition.

A ruler can measure length, does that mean it has consciousness?
 
  • #21


I guess it depends whether it is in principle possible to erase which polarisation the photon takes on (thereby knowing which slit it has gone through), or whether it is in principle possible to determine which slit the photon came through after it hits the screen. I don't know whether we can call the scatter pattern one that shows the photon went through one slit or another.
 
  • #22


questionpost said:
Yeah, an atom *does* technically measure a photon if it absorbs it. You draw the line between measurement and no measurement. If it doesn't collapse it's wave function, it's not a measurement. So if you shine a photon through a prism and the prism doesn't absorb it, then what you get are two polarization angles, the atoms didn't absorb it, so it's still subject to superposition.

A ruler can measure length, does that mean it has consciousness?

Wouldn't an atom have probabilities to whether it absorbs it or not (superposition)? Unless, of course, it has probability 1 of absorbing the photon - then there is no measurement issue there.
 
  • #23


StevieTNZ said:
Wouldn't an atom have probabilities to whether it absorbs it or not (superposition)? Unless, of course, it has probability 1 of absorbing the photon - then there is no measurement issue there.

Sort of. Atoms have different energy levels, and there are only specific energy levels within specific systems and those specific energy levels can only gain or lose specific levels of energy, so if an atom has the right energy to absorb a photon and the photon runs into it, it will absorb the photon, but if it doesn't, the photon may pass by it relatively unaffected or polarized with a slightly different wave function.
 
  • #24
questionpost said:
Yeah, an atom *does* technically measure a photon if it absorbs it. You draw the line between measurement and no measurement. If it doesn't collapse it's wave function, it's not a measurement.
It's not quite so clear-cut. If the atom absorbs the photon, the atom goes into an excited state. If it doesn't absorb the photon, the atom stays unexcited. Suppose the photon can either go left or right, and to the right there's a huge atom that's guaranteed to absorb it if it goes there, so we have two possibilities:
State 1. Photon goes left/atom unexcited
State 2. Photon goes right/atom excited
So instead of thinking of the system as the photon which is in a superposition of left and right states until it's wave function is collapsed by the interaction with the atom, we can instead think of the photon-and-atom system which remains in a superposition of states 1 and 2 until some third object, say a Geiger counter, makes a measurement of the system. But of course, we can also talk about the photon-and-atom-and-Geiger-counter system, whose wavefunction remains in a superposition of states until...

I think you get my point. As Von Neumann proved, in quantum mechanics there is no experimental way to determine the dividing line between measurement device and measured system, and thus no way to find out at what stage of complexity or for what number of particles the wave function "really" collapsed. So the question of where you cut the Von Neumann chain remains. You could cut it at the "top", leading to consciousness-causes-collapse. Or you could not cut it at all and consider the whole universe to be the "observed" system, whose wave function never collapses, leading to the Many Worlds interpretation. Or you could use decoherence to find how high you can make the cut without smearing out interference effects too much.
 
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  • #25


Things become problematic when one starts testing for various superposition states.
 
  • #26


lugita15 said:
It's not quite so clear-cut. If the atom absorbs the photon, the atom goes into an excited state. If it doesn't absorb the photon, the atom stays unexcited. Suppose the photon can either go left or right, and to the right there's a huge atom that's guaranteed to absorb it if it goes there, so we have two possibilities:
State 1. Photon goes left/atom unexcited
State 2. Photon goes right/atom excited
So instead of thinking of the system as the photon which is in a superposition of left and right states until it's wave function is collapsed by the interaction with the atom, we can instead think of the photon-and-atom system which remains in a superposition of states 1 and 2 until some third object, say a Geiger counter, makes a measurement of the system. But of course, we can also talk about the photon-and-atom-and-Geiger-counter system, whose wavefunction remains in a superposition of states until...

I think you get my point. As Von Neumann proved, in quantum mechanics there is no experimental way to determine the dividing line between measurement device and measured system, and thus no way to find out at what stage of complexity or for what number of particles the wave function "really" collapsed. So the question of where you cut the Von Neumann chain remains. You could cut it at the "top", leading to consciousness-causes-collapse. Or you could not cut it at all and consider the whole universe to be the "observed" system, whose wave function never collapses, leading to the Many Worlds interpretation. Or you could use decoherence to find how high you can make the cut without smearing out interference effects too much.

If an atom absorbs a photon, the atom technically measures it. If it doesn't, it's not a measurement.
 
  • #27


questionpost said:
If an atom absorbs a photon, the atom technically measures it. If it doesn't, it's not a measurement.

It just gets entangled. No measurement takes place by the atom.
 
  • #28
questionpost said:
If an atom absorbs a photon, the atom technically measures it. If it doesn't, it's not a measurement.
As I said, you can take the wave function of the photon-and-atom system, and this wave function will not collapse due to any interactions between the photon and the atom. It will only collapse if you use a third object to measure the system.
 
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1. How can I make a homemade pizza crust that is crispy and chewy?

To achieve a crispy and chewy homemade pizza crust, use a combination of all-purpose flour and bread flour. The all-purpose flour will provide a tender texture, while the bread flour will add chewiness. Additionally, bake the pizza on a preheated pizza stone or baking sheet at a high temperature (around 450-500 degrees Fahrenheit) to ensure a crispy crust.

2. What type of cheese is best for homemade pizza?

Mozzarella is the most commonly used cheese for pizza. It has a mild flavor and melts well. However, you can also use a blend of mozzarella and other cheeses like cheddar, parmesan, or fontina for added flavor. It is important to use freshly grated cheese instead of pre-shredded for the best texture and flavor.

3. How do I prevent my pizza toppings from making the crust soggy?

To prevent soggy pizza crust, make sure to fully cook any vegetables or meats before placing them on the pizza. This will remove excess moisture. Also, avoid using too much sauce and do not overload the pizza with toppings. A light layer of sauce and toppings evenly spread out will help prevent a soggy crust.

4. Can I make a delicious pizza without a pizza oven?

Yes, you can still make a delicious pizza at home without a pizza oven. A regular oven or even a grill can work just as well. To get a crispy crust, make sure to preheat your oven or grill to a high temperature and use a pizza stone or baking sheet. You can also use a cast iron skillet to make a pan pizza on the stovetop.

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