Posted by bookofjoe 10/22/2024
Surely anything else would imply a mechanism with additional complexity and indirectly void the entire concept. Delayed entanglement effect doesn't quite have the same cleanness for lack of better word
Pilot wate theory is slowly move in, for example. In 20-50 years it may predict reality better in some cases than existing theories.
It's not possible to use entanglement to transmit information faster than light, even though the entanglement itself could be simultaneous.
None of this is beyond current models though, so I imagine you could predict the results quite well if the calculations were feasible. And if that can be done then that's probably exactly what they did.
(There is a theory in which non-local variables propagate at superluminal speeds, but not instantaneously, but this is a whole other matter).
It doesn't travel faster than the speed of light. Information can't travel faster than c.
No need to worry about Trisolarans.
Supra-luminal signals will almost necessarily imply that it's possible to violate causality by arranging a series of supra-luminal communications. Not every supra-luminal communication violates causality, but it's hard to think of a way to build a consistent theory that would both preclude causality violations and permit at least some supra-luminal signaling.
At superluminal speed, we will be able to hit photons in any order, including reverse order, or emit photons and catch them later. Why this is a problem for casuality?
Similarly, massless particles can't move below the "maximum speed", as they'll have no energy or momentum and won't be able to interact with anything.
The only way to get a zero mass is if the energy is zero, or the velocity is c.
[1] https://profoundphysics.com/why-do-photons-have-no-mass-simp...
We just call it the "speed of light" because it's the speed that massless particles (like photons) travel at in a vacuum.
Einstein once remarked that he went to his office "just to have the privilege of walking home with Kurt Gödel."
https://archive.ph/6doQh#selection-707.279-711.1
https://www.amazon.com/When-Einstein-Walked-G%C3%B6del-Excur...
But this seems to measure the speed at which particles can become entangled in the first place, which I always assumed would've been on the scale of Planck time, but 232 attoseconds is pretty long compared to 10^-43 seconds.
Why are there no practical applications of entanglement?
As explained elsewhere, entanglement cannot be used for faster than light communication because even though change in one particle affects the other particle, without additional information observer sees only a random change.
Then, just by looking in your left pocket, you can learn that your friend has the heads half—instantly!
In other words, it’s not as spooky as it is made out to be.
There's a neat game called the CHSH game that illustrates this. Here's a description [1].
Here's a puzzle equivalent to CHSH but that might be easier for programmers to visualize [1].
Both the ERP, and the explanation of the CHSH with the difference being cos^2(theta) an isn’t that just Malus’s law? So in the case of the ERP experiment, if you fired single polarized particles at a polarizing filter at one angle or the other you still get cos^s(theta) as the difference without requiring entanglement, no?
That implies, in the case of entangled particles there is more than one dimension of “whatever” that causes the polarizing filter to “choose” whether to extinguish the particle on non-equal angles - like azimuth/elevation instead of just theta? It just seems to me that rather than disproving a “hidden variable”, it requires one?
Like I said, I assume I’m missing something and am wrong.
Suppose you did CHSH but instead of pairs of entangled photons with was pairs of non-entangled photons that were polarized in the same direction. They players do the same thing as with entangled photons: use the bit from the referee to pick their measurement angle. A measures at 0 or 45 degrees, where 0 is the axis the photons were polarized on. B measures at -22.5 or 22.5.
Let's say the 0 degrees the players are using is the direction of the original polarization axes.
When the referee gives a 0 to A then A is measuring on the same axis the photon was polarized on, so will get a 1. When the referee gives a 1 to A then A measures at 45 and Malus gives a 50/50 chance of 1.
Player B is always measuring 22.5 from 0, so Malus says B gets a 1 85% of the time.
That gives us this:
Ref A Ref B A's 1/0 chances B's 1/0 chances
0 0 100/0 85/15
0 1 100/0 85/15
1 0 50/50 85/15
1 1 50/50 85/15
If the player's setup isn't aligned with the initial axis the result will differ. For example let's say their set up is 10 degrees off from the setup described above. Then their angles are 10 and 55 for A and -12.5 and 32.5 for B. If I did the numbers right they will win around 62% of the time.
Without entanglement when each player measures a photon the θ for Malus's law is the angle between the axis they measure and the axis the photon was originally polarized with.
With entanglement the θ is the angle between the two axis that the players used.
[1] https://columbia.edu/~ask2262/CourseProjects/KudinoorEntangl...
For example, if we have two balls, each containing a spin mechanism inside them which makes them spin in relation, let's say, to the magnetic north, and we throw one of them to the other...and later we discover that their spin is somehow correlated.
That is not action at a distance, that is the result of the inner mechanism of each ball.
Why not a similar thing happens with particles?
You can play around with this by trying to design the pair of devices that were described in my second link (https://news.ycombinator.com/item?id=35905284).
To recap, you want to design a pair of devices that each have 3 buttons labeled A, B, and C, a red LED, a green LED, and a counter. The counter starts at 1000. When you press any one of the buttons one of the LEDs flashes and the counter decrements. When the counter reaches 0 the device stops responding.
You should also specify a way that if the devices are brought together the pair of them can be reset.
You can specify any kind of non-quantum hardware you want in the devices. As much computing as you need, as much RAM and ROM and disk as you want, and physical sensors. Include clocks if you need to. You can include true random number generators. It doesn't have to be limited to current technology--it just has to be limited to known physics and not use quantum entanglement.
What are need to achieve with that hardware and whatever algorithms you specify is:
1. Suppose someone has used one of the devices, and recorded the results of a very large number of interactions.
Suppose that a statistician is given a list of 5-tuples (P, F, n, R, t) of those interactions with one of the devices, where P is which button was pressed, F is which LED flashed, n is the value on the counter when the button was pressed, and R is how many times the device has been reset (i.e., R = 0 the first 1000 times the device is used, then when it and the other device are reset R = 1 for the next 1000 uses and so on), and finally t is the time at which the button was pressed.
It should not be possible using any known statistical test on that list of 5-tuples for the statistician to distinguish the device from a device whose algorithm is simply:
if any_button_pressed():
r = uniform_true_random_from_0_to_1()
if r < 0.5:
flash(GREEN)
else:
flash(RED)
A couple things to note.
1. The above has to hold even if the users take the devices very far apart from each other before they start pressing buttons.
In particular the users might choose to take the devices so far apart before they start pressing buttons that each has finished their run of 1000 before any possible communications from their device could reach the other.
2. The users might wait a long time before starting a run of 1000, and they might wait a long time between presses within a run.
3. The users are determining when to press independently so you can't count on them alternating. You can't even count on them overlapping: one might do all 1000 presses before user the other starts.
4. The users might use a true random number generator to determine which buttons to press.
I’ll work on the quantum next
To be a reasonable analogy it has to capture something this is different between entangled and not entangled particles. That's the thing that is sometimes described as "spooky" and completely missing from the split coin analogy.
Or your daughter Lisa calls from school and tells you there is meat in her lunch. You immediately know that you must have mixed up the bag lunches that morning and Bart had the vegan meal. You make the lunches together, one vegan and one not, so they are correlated without information transfer.
What makes entangled particles different from other pairs of correlated things is that they correlate in ways the seem impossible without communication.
It's like if someone answered the question of why frogs sometimes rain from the sky by saying that because frogs cannot fly and are heavier than air, just like hail or rain or snowflakes, they feel a downward force from gravity which pulls them to the ground.
It's right...but no one has trouble understanding the gravitational aspect of frogs falling from the sky. The thing people want to understand is how a bunch of freaking frogs got into the sky in the first place.
For example, that two electrons are created in a closed system with a net spin of zero, so as long as you do not allow their waveforms to collapse (EG, so long as the system remains closed) then no matter where they go they must maintain that net spin of zero when perceived in relation to one another.
But if this is the case then the "entanglement" precedes the creation of the particles: it is nothing more than an accounting that they are required to obey in concert by the symmetries of physics.
That's not really the spooky part of entanglement. The rabbit hole goes much deeper, like here[1] or here[2].