If we could know the current state of every particle in the universe, we could accurately predict the future.
Physicists already thought of this. The uncertainty principle forbids knowing a particles position and momentum to within a certain accuracy at the same time. Basically, the more you know of one, the less you know of the other. Applied to any two complimentary. variables.
Turns out, it’s a fundamental property of wave-particle nature of systems.
If you at least read the Wikipedia article on the heisenberg uncertainty principle, you’d know that’s not the case. Although physicists did think that for a long time was what was going on.
I’m not even trying to offer a counter point to whether or not free will exists or not. We don’t know the answer to that question. I was simply providing some context to what OP said, and how it is actually impossible to do.
I’m just a dumb dog, but I’ve never understood why we couldn’t predict the spin of a particle (or why its spin is important). Like… It sounds like a weird philosophical thing more than actual physics and, to my limited understanding, boils down to “we don’t know the truth until we see it.”
Which, I mean… No shit? Is there an easier way of explaining WTF it means in a practical application? Or is that really what it comes down to?
What mechanism actually makes knowing or accurately predicting this information about particles impossible that it isn’t just a measurement issue?
Excellent questions! It isn’t a measurement issue because we’ve actually measured the uncertainty. The uncertainty principle can be expressed as a mathematical equation, which you can then go onto use to derive all the rest of quantum. We’ve used those to create and understand new technologies, like the electron tunneling microscope. Electron tunneling is also the underlying phenomenon behind chemical bonding.
As far as why it’s impossible to know the exact position and speed of an object, the answer isn’t very satisfying – it’s just how the universe works. Learning quantum at first requires a suspension of disbelief to some extent, and it’s not one you need to do on faith. If you look up the double slit experiment, it’s a rather simple setup which demonstrates wave-particle duality, and how observing a wavefunction collapses it. It shows us that uncertainty and quantum fuckery is part of the natural world.
One immediate follow-up question is why we can know the exact position and speed of objects in our everyday lives, which again, is a very good question. The uncertainty principle technically states that we can’t know the exact position and momentum of objects. If we let dX represent uncertainty in position, dP uncertainty in momentum, and dV uncertainty in velocity:
dX * dP = constant
Momentum is just mass times velocity, so:
dX * m * dV = constant
dX * dV = constant/m
This tells us that the product of uncertainty is going to be inversely proportional to the mass of an object. So the bigger something is, the less uncertainty there is about its position and velocity. When something gets really small, say atomic and subatomic sizes, the uncertainty gets very large.
Sorry if this is way more detail than you wanted. I took a few classes in college that touched on quantum, and Physical Chemistry was pretty much all just quantum. I had an excellent professor for it that showed us how you could derive all of it from the uncertainty principle.
It’s because the concept of a particle having definite properties like position and momentum doesn’t hold in the quantum world. Until a measurement is made, the particle is in a superposition of all possible states but with different probabilities, these are described by its wavefunction, which encodes what the various particle variables (position, spin, momentum, etc.) could be.
So, it’s not a measurement issue that introduces the uncertainty; it’s already there as a fundamental property of the particle’s quantum state.
Measurements merely “choose” one of the many possible outcomes, collapsing the wavefunction and in turn making exact measurement of other complementary properties impossible (because the mere act of measuring one variable causes the system to transition into a new state with its own set of probabilities and uncertainties for all variables)
And because these are inherent limitations dictated by quantum mechanics and the uncertainty principle, even if we could know the current state of every particle in the universe, we still couldn’t accurately predict the future because of that fundamental uncertainty.
Also, quantum mechanics is not math that feels right. It is literally the best most experimentally validated theory we have to describe the universe at this time.
Maybe some day we can do better. But it certainly isn’t based on a feeling.
Thats not even true, we’ve been trying to come up with a unifying theory that encompasses quantum gravity for a while. This stuff is hard dude. And you don’t know what you’re talking about at all.
No, it’s hard because the energy levels that we have to have to test things at the plank scale are much higher than anything we can achieve right now with our current level of technology. Plenty of theories make predictions about quantum gravity, string theory, M theory, lopp quantum gravity. There’s even a few out there theories that just try to modify newtonian gravity.
This reminds me of how someone illustrated the machine learning problem of what I want to say is called “gradient descent”. This was way back in the 2000s before all the more recent AI stuff.
Basically the problem as I remember it being described in a Tedtalk was if you think of a problem like a sphere with a surface and a bunch of tunnels at the surface, where only one leads to the core (answer) of the sphere. Some tunnels might get really close to the core, but only one leads into the core. The AI would get stuck diving down these holes using insane amount of computational power trying to dig for the answer, not realizing that if it backed up a bit and went down the hole next to them they could reach the core (answer).
One way to help this problem was developing the game “Foldit” which allowed regular old users to manipulate the proteins themselves. When people had foldit at home running they would notice that the Screensaver displaying the folding would skip over what seemed to be the right shape and would get frustrated that they couldn’t help guide it.
Physicists already thought of this. The uncertainty principle forbids knowing a particles position and momentum to within a certain accuracy at the same time. Basically, the more you know of one, the less you know of the other. Applied to any two complimentary. variables.
Turns out, it’s a fundamental property of wave-particle nature of systems.
What you’re describing is a measurement problem.
Our inability to measure things today does not mean our future selves won’t think of some clever mechanism to do so.
Quantum mechanics is just math that feels right.
There is much we known that we do not known.
If you at least read the Wikipedia article on the heisenberg uncertainty principle, you’d know that’s not the case. Although physicists did think that for a long time was what was going on.
I’m not even trying to offer a counter point to whether or not free will exists or not. We don’t know the answer to that question. I was simply providing some context to what OP said, and how it is actually impossible to do.
I’m just a dumb dog, but I’ve never understood why we couldn’t predict the spin of a particle (or why its spin is important). Like… It sounds like a weird philosophical thing more than actual physics and, to my limited understanding, boils down to “we don’t know the truth until we see it.”
Which, I mean… No shit? Is there an easier way of explaining WTF it means in a practical application? Or is that really what it comes down to?
What mechanism actually makes knowing or accurately predicting this information about particles impossible that it isn’t just a measurement issue?
Excellent questions! It isn’t a measurement issue because we’ve actually measured the uncertainty. The uncertainty principle can be expressed as a mathematical equation, which you can then go onto use to derive all the rest of quantum. We’ve used those to create and understand new technologies, like the electron tunneling microscope. Electron tunneling is also the underlying phenomenon behind chemical bonding.
As far as why it’s impossible to know the exact position and speed of an object, the answer isn’t very satisfying – it’s just how the universe works. Learning quantum at first requires a suspension of disbelief to some extent, and it’s not one you need to do on faith. If you look up the double slit experiment, it’s a rather simple setup which demonstrates wave-particle duality, and how observing a wavefunction collapses it. It shows us that uncertainty and quantum fuckery is part of the natural world.
One immediate follow-up question is why we can know the exact position and speed of objects in our everyday lives, which again, is a very good question. The uncertainty principle technically states that we can’t know the exact position and momentum of objects. If we let dX represent uncertainty in position, dP uncertainty in momentum, and dV uncertainty in velocity:
dX * dP = constant
Momentum is just mass times velocity, so:
dX * m * dV = constant
dX * dV = constant/m
This tells us that the product of uncertainty is going to be inversely proportional to the mass of an object. So the bigger something is, the less uncertainty there is about its position and velocity. When something gets really small, say atomic and subatomic sizes, the uncertainty gets very large.
Sorry if this is way more detail than you wanted. I took a few classes in college that touched on quantum, and Physical Chemistry was pretty much all just quantum. I had an excellent professor for it that showed us how you could derive all of it from the uncertainty principle.
It’s because the concept of a particle having definite properties like position and momentum doesn’t hold in the quantum world. Until a measurement is made, the particle is in a superposition of all possible states but with different probabilities, these are described by its wavefunction, which encodes what the various particle variables (position, spin, momentum, etc.) could be.
So, it’s not a measurement issue that introduces the uncertainty; it’s already there as a fundamental property of the particle’s quantum state.
Measurements merely “choose” one of the many possible outcomes, collapsing the wavefunction and in turn making exact measurement of other complementary properties impossible (because the mere act of measuring one variable causes the system to transition into a new state with its own set of probabilities and uncertainties for all variables)
And because these are inherent limitations dictated by quantum mechanics and the uncertainty principle, even if we could know the current state of every particle in the universe, we still couldn’t accurately predict the future because of that fundamental uncertainty.
Also, quantum mechanics is not math that feels right. It is literally the best most experimentally validated theory we have to describe the universe at this time.
Maybe some day we can do better. But it certainly isn’t based on a feeling.
Quantum mechanics proves that quantum mechanics is valid.
It is the mostly widely accepted interpretation but it is not the only one.
We’ve been confident before and spent centuries chasing literal ether.
The Copenhagen interpretation is just that, an interpretation.
We’ve chased it for decades and are no closer to resolving it with classical mechanics.
I’m sure future scientists to scoff our demand that there be an “observer”
It still cannot account for gravity.
The formulas pretend it doesn’t exist. It reminds me of a physicals 101 class pretending friction doesn’t exist.
Friction exists and so does gravity, therefore they are both pretend.
Thats not even true, we’ve been trying to come up with a unifying theory that encompasses quantum gravity for a while. This stuff is hard dude. And you don’t know what you’re talking about at all.
Trying and failing.
Is it not possible that it’s “hard” because we’re chasing the wrong path.
This isn’t something I alone think. You seem to be under the impression I have a less than Wikipedia level understanding of this. I do not.
No, it’s hard because the energy levels that we have to have to test things at the plank scale are much higher than anything we can achieve right now with our current level of technology. Plenty of theories make predictions about quantum gravity, string theory, M theory, lopp quantum gravity. There’s even a few out there theories that just try to modify newtonian gravity.
It’s “hard” because we didn’t find what we expected at the energy levels we targeted.
There is too much funding behind it now. No one can question the status quo and maintain funding.
As I said, you don’t know what you’re talking about. That’s all there is to this conversation.
This reminds me of how someone illustrated the machine learning problem of what I want to say is called “gradient descent”. This was way back in the 2000s before all the more recent AI stuff.
Basically the problem as I remember it being described in a Tedtalk was if you think of a problem like a sphere with a surface and a bunch of tunnels at the surface, where only one leads to the core (answer) of the sphere. Some tunnels might get really close to the core, but only one leads into the core. The AI would get stuck diving down these holes using insane amount of computational power trying to dig for the answer, not realizing that if it backed up a bit and went down the hole next to them they could reach the core (answer).
One way to help this problem was developing the game “Foldit” which allowed regular old users to manipulate the proteins themselves. When people had foldit at home running they would notice that the Screensaver displaying the folding would skip over what seemed to be the right shape and would get frustrated that they couldn’t help guide it.
This might be a different Ted Talk, but it is about the same subject.
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