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/sci/ - Science & Math

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4961259 No.4961259 [Reply] [Original]

What is the fastest rate at which we can receive information? Is it the speed of light?

Ponder this: Two particles are in a superposition of each other and correlated, then separated. When a measurement is taken on one of the particles, the other particle MUST be in an opposite state. Therefore, if the two particles are separated by a large distance and the first particle is determined to be spin up, then we know at that instant, the second particle is spin down. Even with a large distance separation, how do we know the state of the second particle immediately, thus faster than the speed of light?

>> No.4961265

You're not really communicating information, are you?

Ask yourself this: could you use this mechanism to send a picture of your wang to Alpha Centauri?

>> No.4961264

It appears to us to be instant receival of information from the particle. It's like looking in the mirror, the photons take time from the reflection of you to get to your retina, just like it takes time from the photons from the observation to get to your retina. The entanglement process might be instant, but the receival of the observation and the processing of it in your brain takes time nonetheless.

>> No.4961269

>>4961259
This is possibly action at a distance, but this cannot be used to transmit information FTL.

>> No.4961270

>>4961259
entanglement supposes an interconnected universe that each and every change has an immediate effect on the universe

>> No.4961275

But you're not sending or receiving information, you're just making a logical deduction based on quantum states.

>> No.4961277

>>4961265
i might be able to. if i take a measurement of my qubits "here" and the wavefunction collapses, then the qubits "there" are stuck in the opposite state

>> No.4961280

>>4961277
Yes, and? The state of collapse of the first particle is apparently random.

Here. Send me a "yes or no" message, just a single bit, using entanglement. Describe the apparatus.

>> No.4961281

>>4961277
Yes, but you can't control what you measure. You can't choose to measure spin up, for example. There is no way for Alice to see whether Bob has measured his particle or not, simply by measuring the particle that went her way.

>> No.4961283

>>4961277
and in this case, lets only give qubits +1/2 or -1/2 spin, representing 1 or 0. Therefore, the data "there" measured after the collapsed wavefunction will either be jibberish or data. if it's jibberish, then they need to flip the qubits. if it's data, then they have the original data. there would be no need for communication between the two entities, thus eliminating the need for sending communication at the speed of light

>> No.4961292

continuing >>4961283, it would alleviate the need for alice or bob to communicate what they have >>4961281

>> No.4961297

quantum entanglement DOES NOT sent any information.

this can also be seen in the fact that its imposable to determine who collapsed the wave-function since its symmetric, you can see it as a measurement of A collapsing B, or a measurement of B collapsing A.

>> No.4961300
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4961300

this could not be used to send information at any given time..but..

could it be used to send information FTL if there were standardized times to view the information?

suppose two boxes, each one has two entangled particles in it.
one box goes to mars, one stays on earth
at some point before 5pm earth time, physicists change the quantum states of the particles to read the binary "2" (10, up and down)

at exactly 5pm earth time, on mars, someone opens the box on mars to read the contents, they will see the particles with a spin contingent with the the binary opposite of 2, which is 1 (01, down and up). so the information has been sent FLT, so long as there are standardized observation times.

does this work?
why or why not?

>> No.4961302

>>4961283
> if it's jibberish, then they need to flip the qubits. if it's data, then they have the original data
wat

>> No.4961305

>>4961300
>at some point before 5pm earth time, physicists change the quantum states of the particles to read the binary "2" (10, up and down)
Can't do that. No known method.

>> No.4961311

>>4961305
no known or no possible way?
i assume it must be known in some way, otherwise quantum computing is going to be a little tricky

>> No.4961312

>>4961311
>quantum computing
In the nicest way possible, you don't know what you're talking about. It would do you well to look a little more into this.

>> No.4961313

>>4961300
no, that's not how it works.

at 4:45 you measure the earth particle, you now see its 0 or 1, as if it was a normal measurement. at this moment the entanglement is disrupted and the particles are completely separated, if you change it now from 0 to 1 or 1 to 0, it will have no effect on the mars particle.

at 5:00 the mars particle is measured, the now find it is 0 or 1, like a normal measurement.

at a later time mars receives a communication from earth saying the got a 1, and look at that mars has a 0! or if earth had a 0 mars has a 1. so the particles were indeed entangled.

>> No.4961317

>>4961297 and >>4961302
i see that the stream of single qubits wouldn't work. however, can more than one particle be correlated. let's say 10 qubits at A and 10 qubits at B. If you have a .jpg image in qubit binary at A, then the opposite bits must be at B. At any moment in time at B when the wavefunction is measured, the image is either "right side up" or "upside down". if it's upside down, you flip the bits
>using "right side up" and "upside down" as terms for flipped bits


>>4961300
there's no way of guaranteeing it's 10 on earth. there's a 50/50 chance it's 10 or 01 at that time on earth, therefore, you cant be sure which one it is on mars

>> No.4961320

>>4961317
Nope. Entanglement only comes in pairs.

>> No.4961321

>>4961312
Actually, here:

Basic description of Bell's inequalities
http://www.stat.physik.uni-potsdam.de/~pikovsky/teaching/stud_seminar/Bell_EPR-1.pdf

>> No.4961328

>>4961320
this is an instance where there is currently no known way. we didn't initially know that particles could be in a superposition of each other, it was found. the transmission of UNENCRYPTED data would certainly be possible if we can have more than one correlated particle at each location

>> No.4961334

>>4961328
is there no response because you guys think it's possible and are thinking. or am i wrong?

>> No.4961338

>>4961317
but how will you get the jpg at A? you will get a random number in binary. and you cant flip it becasue after seeing its not a jpg you need to re-entangle the particles so you have to go get the B particles again and repeat until you happen to get the correct A. and when that happens B will only know its the correct one when the get a message sub light that its the correct one. so no information is sent actually.

>> No.4961339

>>4961328
>>4961334
>possible
All of the known evidence indicates that there is no method to do any of that. Entanglement comes in pairs only. Once you disturb one of the entangled particles then the entanglement is broken. The initial states of the entangled particles is apparently random and not measurable except by disturbing one of the entangled particles thereby breaking the entanglement.

>> No.4961341

>>4961328
>>4961320
entanglement can come in more than pairs, but you don't get any additional properties with it. you can have 3 particles that has to sum to 1, so measure the first to and find 0 and 1 and the last one collapses to 0.

>> No.4961345

>>4961341
My apologies. Thanks.

>> No.4961366

>>4961341
i need to think about this some more.

1 qubit:
1 at A
0 at B

2 qubits:
01 at A
10 at B

10 qubits:
1010101010 at A
0101010101 at B

Or am I wrong, and each correlated particle in the wavefunction is random? but it can't be because it's correlated

>> No.4961375

>>4961341
the coefficients squared in a superposition wavefunction must add up to 1, that is correct. but how does that relate?

>> No.4961377

>>4961366
no those are possible states. in this case you have 1,2 and 10 pairs of entangles qubits.

>> No.4961381

If you have 1 million entangled particles, you have enough for a jpg image

>> No.4961382

I've had the exact same idea. Apparently, it doesn't work. Too bad.

>> No.4961387

>>4961375
relate to what? im just pointing out you can have more than just a pair.

>> No.4961516

>>4961387
Ok. I thought you were saying it was impossible to have many correlated particles, all with known states, however, the probability of each state doesn't relate to which state the particles are in.