Why have so many physicists shrugged off the paradoxes of quantum mechanics?
1–10 of 132 posts
Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?
#2> Bohr postulated a distinction between the quantum world and the world of everyday objects. A “classical” object is an object of everyday experience. It has, for example, a definite position and momentum, whether observed or not. A “quantum” object, such as an electron, has a different status; it’s an abstraction. Some properties, such as electrical charge, belong to the electron abstraction intrinsically, but others can be said to exist only when they are measured or observed.
This is a common error. Macroscopic "everyday" objects don't have a definite position and momentum. Macroscopic objects are quantum objects. But when the mass is big enough, the position and momentum can be defined simultaneously with an error that is so small that you can just ignore the uncertainty and approximate them as classical objects.
(Looking at them as classical objects is just a good approximation, like ignoring the gravity force of the Moon in most common situations.)
Anyway, the measurement problem is a real problem and nobody knows how to solve it. The current fade is to use decoherence to explain it. It is a promising idea, so I hope that in a few years/decades/centuries we can give a good explanation of the measurements that avoid anything that looks like magic.
Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?
#3> Bohr postulated a distinction between the quantum world and the world of everyday objects. A “classical” object is an object of everyday experience. It has, for example, a definite position and momentum, whether observed or not. A “quantum” object, such as an electron, has a different status; it’s an abstraction. Some properties, such as electrical charge, belong to the electron abstraction intrinsically, but other…
can we measure that imprecision of momentum/position relation even though small?
Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?
#4> Bohr postulated a distinction between the quantum world and the world of everyday objects. A “classical” object is an object of everyday experience. It has, for example, a definite position and momentum, whether observed or not. A “quantum” object, such as an electron, has a different status; it’s an abstraction. Some properties, such as electrical charge, belong to the electron abstraction intrinsically, but other…
can we measure that imprecision of momentum/position relation even though small?
h/2pi ?
That likely applies to not just light, but everything.
Do we really need that much precision to get what we want? Can we flip it, and just say as long as we can do that, there's still hope to spark up another big bang when everything is cold and expanded?
Are they doing something useful by asking these questions or just trying to make a name for themselves, or learn on your dime?
Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?
#5They aren't paradoxes of quantum mechanics.
They are a paradox between how we intuitively expect the world to work and reality. Our intuition is wrong.
Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?
#6> Bohr postulated a distinction between the quantum world and the world of everyday objects. A “classical” object is an object of everyday experience. It has, for example, a definite position and momentum, whether observed or not. A “quantum” object, such as an electron, has a different status; it’s an abstraction. Some properties, such as electrical charge, belong to the electron abstraction intrinsically, but other…
can we measure that imprecision of momentum/position relation even though small?
I believe gus_massa was just saying that we simply define out of existence this supposed problem with measurement (for macro objects). This is done because even though the 'furniture of the world'/everyday objects/macroscopic objects are still quantum entities, at this level, error rates are such that they can be treated in a classical manner.
Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?
#7> Bohr postulated a distinction between the quantum world and the world of everyday objects. A “classical” object is an object of everyday experience. It has, for example, a definite position and momentum, whether observed or not. A “quantum” object, such as an electron, has a different status; it’s an abstraction. Some properties, such as electrical charge, belong to the electron abstraction intrinsically, but other…
I thought the current fad was to use holography to explain it. The problem is that to measure something in quantum mechanics requires separating the world into two systems. To make exact measurements, the observing system has to be infinitely large to avoid quantum fluctuation, and the experiment has to be repeated infinitely often because it is probabilistic.
To deal with the infinite size, particle physicists push the observer systems out to infinity. This is fine for scattering experiments because collider detectors are so large and far away from a collision it might as well be infinity, but this poses a problem for quantum gravity and cosmology.
It seems that the most popular approaches to dealing with it have been based on Juan Maldecena's AdS/CFT correspondance, which is a toy model that allows those observers off at infinity to live on the boundary of spacetime and to describe the behavior of the interior entirely in terms of the projection of that behavior onto the boundary.
The challenge is that our universe doesn't look like Anti de Sitter space, but rather like (plain) de Sitter space, and so there is no natural boundary to project onto, which has led some physicists to question the legitimacy of dividing the quantum mechanics need to divide the world into 2 systems.
The measurement problem seems like an artifact of that, and what's really happening is that measurement causes the two systems to become entangled. Wave function collapse would then be the subjective result of the two systems entering a mixed state, because the observed system can no longer be described independently of the system that just observed it.
Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?
#8> Bohr postulated a distinction between the quantum world and the world of everyday objects. A “classical” object is an object of everyday experience. It has, for example, a definite position and momentum, whether observed or not. A “quantum” object, such as an electron, has a different status; it’s an abstraction. Some properties, such as electrical charge, belong to the electron abstraction intrinsically, but other…
can we measure that imprecision of momentum/position relation even though small?
No. It would take far more digits of accuracy than we can measure.
For example, here's an object of 1 kg mass. The product of the uncertainty of its position and momentum is h-bar / 2, or h / 4 pi, which is about 5e-35 kg m^2/s. We're going to measure the position to one wavelength of visible light (say, 500 nm wavelength, so 5e-7 m). That means that we need to be able to measure the momentum to an accuracy of 1e-28 kg m/s, which for a mass of 1 kg means measuring the velocity to within an accuracy of 1e-28 m/s. Good luck with that...
Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?
#9> Bohr postulated a distinction between the quantum world and the world of everyday objects. A “classical” object is an object of everyday experience. It has, for example, a definite position and momentum, whether observed or not. A “quantum” object, such as an electron, has a different status; it’s an abstraction. Some properties, such as electrical charge, belong to the electron abstraction intrinsically, but other…
Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?
#10They aren't paradoxes of quantum mechanics. They are a paradox between how we intuitively expect the world to work and reality. Our intuition is wrong.
you could say that about any paradox. it other words, it isn't a helpful position because it doesn't give any insight. why even have the word paradox?
plus, our intuition is just as much a part of reality as your "reality".