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Post Reply Whats is your opinion on Quantum Mechanics?
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Posted 6/17/16

nanikore2 wrote:


Jophar_Vorin wrote:


nanikore2 wrote:

It is a practical model just like all the other models. See Copenhagen interpretation of quantum mechanics.

Schrodinger's cat is not "both dead and alive" or "neither dead nor alive" because it's a probability and not actuality. When a measurement is taken, the cat would be either alive or dead.


Uhh, from what i have read isnt it that a particle doesnt have properties until it is measured.. And that we can only "estimate" the properties when not measured?


It's technically so. I haven't been keeping up with the latest.


Fabulous. ( ͡° ͜ʖ ͡°).

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Posted 6/17/16
i'm not going to pretend i have even a grain of knowledge in this subject. i wonder how the quantum computers will change technology
(iirc Google/Microsoft already have quantum computers)
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Posted 6/17/16

namealreadytaken wrote:

i'm not going to pretend i have even a grain of knowledge in this subject. i wonder how the quantum computers will change technology
(iirc Google/Microsoft already have quantum computers)


D-Wave is best Quantum Computer ( ͡° ͜ʖ ͡°)

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Posted 6/17/16
Science hurts my small brain.
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Posted 6/17/16 , edited 6/17/16
Sigh...

So, I've taught quantum mechanics at the graduate level. It's not magical - hell, it isn't even all that weird. Conservation of probability over time (called unitarity), linear algebra, and complex numbers are really all you need.

The hardest thing about quantum mechanics is letting go of the belief that particles are little dots that move around. That's all the uncertainty principle means: you can't measure the position and velocity of a particle infinitely precisely, because that information doesn't exist. The practicing physicist doesn't even think about wave-particle duality, because the formalism doesn't make that distinction - either perspective is legitimate.
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Posted 6/17/16
As for Schrödinger's cat, the physicist (subscribing to the Copenhagen interpretation, which is the most reasonable and widely-held) will say two things:

1. If the situation "50% chance the cat is alive, and 50% that it's dead" were actually physically realizable, then the cat would be neither alive nor dead. Rather, the cat would no longer be a system for which that piece of information existed.

2. That situation (or state, rather) isn't actually possible to create, because the cat is made of so many atoms (more than 10^23) that the wavefunction automatically collapses to "alive" or "dead." There are too many degrees of freedom to sustain the superposition.
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Posted 6/17/16

auroraloose wrote:

As for Schrödinger's cat, the physicist (subscribing to the Copenhagen interpretation, which is the most reasonable and widely-held) will say two things:

1. If the situation "50% chance the cat is alive, and 50% that it's dead" were actually physically realizable, then the cat would be neither alive nor dead. Rather, the cat would no longer be a system for which that piece of information existed.

2. That situation (or state, rather) isn't actually possible to create, because the cat is made of so many atoms (more than 10^23) that the wavefunction automatically collapses to "alive" or "dead." There are too many degrees of freedom to sustain the superposition.


Not exactly. The canonical viewpoint is closer to the second one, but even that's not quite right. The maxim of QM is that a wavefunction collapses (or becomes highly localized) when observed by an observer. The geiger meter, however, is the observer and thus whether or not radiation occurs (i.e. the wavefunction collapses into "decay" or "not decay" state), at which point the system is too macroscopic for quantum mechanics to play any big role. I suppose you could say that the cat collapsed to the "alive" or "dead" state because it too is macroscopic, but the geiger meter and radioactive material also form a macroscopic system per se.

There's also the nature of the collapse itself, which is what most interpretations of QM try to examine. However, no QM interpretation is close to canon (Copehagen does come closest, but most physicists seem to remain agnostic on the issue); however, if the Shroedinger Cat experiment gives any insight, most people would agree the important physics comes to how an instrument effects the quantum system its examining.
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Posted 6/17/16

nanikore2 wrote:

It is a practical model just like all the other models. See Copenhagen interpretation of quantum mechanics.

Schrodinger's cat is not "both dead and alive" or "neither dead nor alive" because it's a probability and not actuality. When a measurement is taken, the cat would be either alive or dead.


That is true only if you are viewing the universe through the limited prism of human perception. The cat is both alive and dead in different dimensions.


1) Space, Length
2) Space, Width
3) Space, Height
4) Time, Length = Linear Time, Time as we know it, traveling in a straight line moving forward.
5) Time, Width = Parallel realities, where all possible causalities exist. Two separate time lines parallel to one another, one where the chain of causality went one way, and one that went the other way.
6) Time, Height = Parallel realities, where all Impossibilities exist. Perhaps there are alternate dimensions spawned by our acts of imagining them... or maybe our imaginations don't belong to us at all, but instead, it is just the act of our consciousness perceiving one of these other realities for just a moment.
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Posted 6/17/16


You're right - it's the cat + equipment that's the whole system. At that point though there's not much reason to distinguish between a cat and a geiger counter, as they're both just large collections of atoms. A proper solution the measurement problem should be observer-agnostic, since there's no reason to exclude the human scientists from the universal wavefunction. In that sense an "observer" is really just a large-enough collection of particles, and collapse has to be explained in those terms.
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Posted 6/17/16

rcn_cra wrote:


nanikore2 wrote:

It is a practical model just like all the other models. See Copenhagen interpretation of quantum mechanics.

Schrodinger's cat is not "both dead and alive" or "neither dead nor alive" because it's a probability and not actuality. When a measurement is taken, the cat would be either alive or dead.


That is true only if you are viewing the universe through the limited prism of human perception. The cat is both alive and dead in different dimensions.


1) Space, Length
2) Space, Width
3) Space, Height
4) Time, Length = Linear Time, Time as we know it, traveling in a straight line moving forward.
5) Time, Width = Parallel realities, where all possible causalities exist. Two separate time lines parallel to one another, one where the chain of causality went one way, and one that went the other way.
6) Time, Height = Parallel realities, where all Impossibilities exist. Perhaps there are alternate dimensions spawned by our acts of imagining them... or maybe our imaginations don't belong to us at all, but instead, it is just the act of our consciousness perceiving one of these other realities for just a moment.


Very few physicists believe something like the many-worlds hypothesis.
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Posted 6/17/16 , edited 6/17/16
I don't know much about it, but I've heard that once you really get into it, what you come to find is the most mysterious and shocking discovery. For example, there's this thing where if you take two particles and move them away from each other, if you turn one particle, the other particle turns as well, even though they are no where near each other. Which means that there is an underlying connection between EVERYTHING, just like the Buddhist's have been saying for centuries. Also, this one is pretty creepy but it is fucking crazy, there is this experiment where a particle reacts differently depending on if there is an observer. Basically, your thoughts affect reality.... crazy stuff.

One of the most famous physicist Niels Bohr once said:

"If quantum mechanics hasn't profoundly shocked you, you haven't understood it yet."

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Posted 6/17/16 , edited 6/17/16

KurdishSenpai wrote:

I don't know much about it, but I've heard that once you really get into it, what you come to find is the most mysterious and shocking discovery. For example, there's this thing where if you take two particles and move them away from each other, if you turn one particle, the other particle turns as well, even though they are no where near each other. Which means that there is an underlying connection between EVERYTHING, just like the Buddhist's have been saying for centuries. Also, this one is pretty creepy but it is fucking crazy, there is this experiment where a particle reacts differently depending on if there is an observer. Basically, your thoughts affect reality.... crazy stuff.

One of the most famous and renounced physicist Niels Bohr once said:

"If quantum mechanics hasn't profoundly shocked you, you haven't understood it yet."



Einstein taunted it as spookie distant effect. Yes he had his problems with quantum entanglement but I still think it's the better name .

Edit: Or spooky action at a distance I'm not exactly sure wich translation is right.
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Posted 6/19/16

rcn_cra wrote:

6) Time, Height = Parallel realities, where all Impossibilities exist. Perhaps there are alternate dimensions spawned by our acts of imagining them... or maybe our imaginations don't belong to us at all, but instead, it is just the act of our consciousness perceiving one of these other realities for just a moment.


Dealing with parallel universes would push the investigation out of the realm of physics and into metaphysics.

(This is off-topic but should it be true that aspects of consciousness is super-dimensional, then the main plot point of Macross Delta would actually be sorta plausible!)
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Posted 6/20/16
The main problem this thread has is most of the people here don't now anything, and are just throwing words around. While I barely know anything the teacher is of course right that it's not magical or mysterious. The math for basic quantum mechanics is fairly simple. Most of the difficulty is from infinite sums, as far as I understand.

To get a few things out there, the waves from the wave equations aren't exactly probability. They can have complex number amplitudes. And they "exist" in configuration space. At the end if you want to know where you are in configuration space you take the integral over the square of the magnitude. And that gives you the relative probabilities of being in one region or another.

Isolated particles, can be calculated while ignoring the dimensions from the rest of the universe. They're a part of the wave that factors out. Entangled particles are parts of the wave that can't be factored out form each other in a specific way. Causality is still local in configuration space so lumps of complex amplitude that are far apart can't effect each other much.

An observer is any thing that splits the lump. When you look at the particle the complex amplitude from each possible state becomes correlated with your brain states, and each lump is now to far apart to interact with each other. So an observer doesn't need to be conscious at all.

Roughly speaking the many world interpretation says that each lump keeps on existing, and often will contain a collection of particles called <insert your name>. Why you observe yourself ending up in the larger lumps so often is left unexplained.

The Copenhagen interpretation say the other lumps stop existing, with the observed probabilities. Again the probabilities are unexplained.

There are a lot of patterns that MW's follow's that hold throughout physics, such as locality, and it is slightly simpler. The Copenhagen interpretation raises fewer metaphysical questions.
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Posted 6/20/16
The interesting thing is how do we define "free will". I'm not convinced probability would lend itself to giving living beings any agency, or self determination. It's weird to think that we are the result of some arbitrary complex causes and effects. This is probably a little tangential, but sometimes I've heard people regarding the topic of quantum physics and that being unable to with 100% accuracy predict a particle's position and velocity somehow leads to free will.
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