Why Can't You Use Quantum Mechanics To Communicate Faster Than Light?
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- Опубликовано: 5 сен 2024
- The EPR paradox, that we met in a previous video, tells us 2 entangled particles can effect each other no matter now far away they are. But then why can't we use them to send instant messages across the universe? Einstein's relativity tells us it would be a disaster if we could!
Homework:
Prove that faster than light communication doesn't work for the state in the video, when Alice measures up and down-ness, but Bob measures left-rightness.
Look up and then explain the usefulness of a one-time pad. Also explain whether a one time pad coming from a bunch of shared particles is secure if Eve is trying to measure Bob's particle's before he does.
The EPR paradox, that we met in a previous video, tells us 2 entangled particles can effect each other no matter now far away they are. But then why can't we use them to send instant messages across the universe? Einstein's relativity tells us it would be a disaster if we could!
Homework:
Prove that faster than light communication doesn't work for the state in the video, when Alice measures up and down-ness, but Bob measures left-rightness.
Look up and then explain the usefulness of a one-time pad. Also explain whether a one time pad coming from a bunch of shared particles is secure if Eve is trying to measure Bob's particle's before he does.
Solution to homework question 1:
Sorry RUclips doesn't allow certain brackets in the description, so I've put the solution as a comment.
I'll never accept it. Feck the universe. We will find a way.
Until the 1900 the world KNEW that it was IMPOSSIBLE to build something like a plane and to fly ...
I need to find a way for it to work, it's the major requirement for my plans!
@@Maisonier Dumbest argument ever. "Maybe it does exist but we just haven't discover it yet".
By that argument unicorns exists because we haven't discover it yet.
Science is done on proven ground, with evidences and proofs. These FTL communication using quantum mechanics have no proofs or evidences so they're impossible. What make you think we can make it possible in the future? Just because we've done it before with other stuff? "Correlation does not imply causation". Just because we've done it before with other stuff doesn't mean we can do it again. What if there's no other ways? What if it is impossible?
@นายเตชภณ คำพู Dumbest argument ever. "Maybe it does exist but we just haven't discover it yet".
By that argument unicorns exists because we haven't discover it yet.
Science is done on proven ground, with evidences and proofs. These FTL communication using quantum mechanics have no proofs or evidences so they're impossible. What make you think we can make it possible in the future? Just because we've done it before with other stuff? "Correlation does not imply causation". Just because we've done it before with other stuff doesn't mean we can do it again. What if there's no other ways? What if it is impossible?
@@luongmaihunggia you fail to make a good analogy because one thing has nothing to do with the other. Today of course we have the knowledge to know that unicorns do not exist but a century ago that would still be very debatable, today Quantum Mechanics are for us what Unicorns were for a century ago people, that's the whole point. FTL communication could or could not be possible but we're too low on information and experimentation to know anything for sure. If I said that black holes have a probability of being a interdimensional portal to another point on the universe you couldn't say that I'm wrong or right because that's not what science is about, it's about knowing what something isn't. There's so much about a lot of things that we don't understand yet that is stupid to just say that because we have no proofs or evidence yet than they're impossible... that's a pretty limited way of thinking about things.
I like that she included that last bit because that to me seemed like the solution to the problem that I haven't seen anyone mention.
Yeah
Glad to see you're feeling better and back in action :-)
Thanks! And the phd was a bit quite for the last week so I could finally do this.
do you guys know each other? 😲😲 you two are favorite youtubers thank you very much for all your videos
* my favorite
i know I am kind of off topic but do anyone know of a good website to stream newly released series online?
@@LookingGlassUniverse in regards to FTL communication using Quantum Entanglement, would this idea work? There is one piece of information we can send and measure on both sides accurately using entanglement, TIME. Or more specifically TIME intervals. Use the first measurement as the signal for the person receiving the message to begin counting then count the time elapsed until the next measurement. We assign letters and numbers to each moment of time that passes by BEFOREHAND using that as our “key” that we give to both the sender and the receiver. So if one second elapses between the 1st and the 2nd measurement that equals the letter A. If two seconds pass by then it's the letter B. First “ping” or measurement is the starting point and the second ping is the end point. Count the time interval in between and refer to a “key” to find out what letter or number that time interval represents. We can write sentences this way. And just ignore the spins altogether because we are only using the entangled particles to tell us when to start counting and when to stop counting. It is the time interval between measurements that is relaying the message not the spin. As long as both observers have the same "key", wouldn't that work? Would just need a ton of entangled particles as some have stated that once you interact with an entangled pair, that breaks the entanglement. We would basically be using 2 entangled pairs to spell out one letter. Use one entangled pair as the starting point and another entangled pair as the end point for the count. Then wait a minute between each letter we’ve sent as a reset before we send the next letter and repeat until a word is spelled out.
Here's a possible solution (Please correct me if I make a mistake):
Instead of using the direction of the spin to communicate, how about we use the fact of whether the spin changes or not? If Alice keeps observing her particle, it will not be able to collapse in a different state when bob observes his own. So Bob runs 5 or 10 measurements, if they are all the same then that means that Alice is observing her particle, that means "Yes". If they are different however, that means Alice is not observing her particle, that means "No"
@@nathanborak2172 I thought particles had a 50% chance of collapsing up or down when they weren't being observed
I'm so excited that I found this channel. Your ability to lay out complicated ideas in a simple yet elegant way reminds me of channels like PBS SpaceTime or 3Blue1Brown. I hope that you keep your material math-heavy too, I really appreciate that aspect of your content!
I had wondered about this myself and found your video by randomly searching to see if someone else had the same idea. Really interesting stuff.
I have just found your channel and am so happy to have done so. I'm way past uni but as a math/physics geek it's fantastic to find someone giving the math (guess where I'm from and yes we have it wrong here) in a delightful presentation style.
The questions you leave, those items you didn't know at the time of upload, and even the mistakes you yourself point out have me digging for answers - as do the discussions from the community of commenters.
Thank you so much and now I have some homework to do!
Here is my solution to the Homework question 1!
What you need to prove it that, Bob's probability of getting left is the same whether or not Alice measured. This means his measurement doesn't reveal what Alice did and so they can't communicate this way.
To make this easier to type, I'm going to write up=|0>, down=|1>, right=|+> and left=|-> (these are the standard conventions in quantum information theory.)
The proof has lots of cases. The two main cases are:
1) Alice doesn't measure up/down-ness (ie 0/1 ness)
2)Alice does measure up/down-ness (ie 0/1 ness)
But 2) has 2 subcases:
2a) Alice measures up (0)
2b) Alice measures down (1)
1) first. This is the same idea as in the video: we have to rewrite the parts of the wavefunction belonging to Bob in the +/- basis (since that's what he's going to measure).
The original wavefunction is 1/√12 (|10>+|11>+|00>) + √3/2 |01>
In the new basis it is: 1/√6 |1+>+√(2/3)|0+>+ 1/√6|0-> (sorry this calculation is too annoying to write it full!)
Using that, we see that the chance Bob get's + is (1/√6)^2+√(2/3)^2= 1/6+2/3= 5/6
2) Let's rewrite the wavefunction a tiny bit more: 1/√6 |1>|+>+|0>(√(2/3)|+>+ 1/√6|->) (just grouped some terms) then a bit more:
1/√6 |1>|+>+√(5/6)|0>(√(2/3)|+> + 1/√6|->)/√(5/6) all I did here was normalise (√(2/3)|+> + 1/√6|->)/√(5/6) this vector (ie now it has length 1).
2a) Say alice measures 0. This happens with 5/6 probability because that's the coefficient in front of the 0 part of the vector. Afterwards, Bob's state is (√(2/3)|+> + 1/√6|->)/√(5/6). So his probability of getting + is (2/3)/(5/6)=4/5
2b) Say Alice measure 1: This happens with probability 1/6. Bob's new state is just |+> so he'll definitely measure +
So if we didn't know which result Alice got, Bob's overall probability of getting + is 5/6* 4/5+1/6*1= 2/3+1/6=5/6
But that's exactly the same as in case 1!! Phew. Quantum mechanics isn't broken. Well done you.
Looking Glass Universe in your earlier videos there are people who gave you their "research" on your videos. I'm sure this research wouldn't fit into a RUclips thread. How did they give it to you? Is there a way to send you our long ramblings on these confusing ideas (email or something similar)?
They did just comment it! But I agree, I need a better way....
I second this. My professors aren't too knowledgeable on the subjects you have here. It would be nice to speak to someone with an educated insight, as I'm attempting to write a paper.
"A plant will face towards sunlight. A pendulum will never reach higher than the point it was dropped. One does not describe a plant, or pendulum as conscious though (the plant doesn’t have a will to live; nor does the pendulum get tired) it is merely a function of the object. This researcher deems that electrons are the same. An electron does not know about measurement but instead reacts to it. One could say that instead of the measurement collapsing the electron’s wavefunction, the electron collapses itself based on the stimuli of the measurement. The way for such a thing to occur instantaneously is through retro-causality. This will be explained further in the paper."
This is the first paragraph, I would love to work with you and explain in detail what I mean in my (beginnings of a) theory.
-Chris
This being a (possible) solution for the measurement problem you brought up in your Schrodinger equation videos.
P.S your vids are a great, thought-provoking, inspiration :) and you should know that there are more people appreciating your efforts than the whole population of the country of San Marino...
Would you mind summarising the argument for me here? I think that retro causality would be pretty unpleasant, but perhaps you've gotten around the issues?
As someone who has a background in Physics, I always went along with the accepted point that the randomness within a quantum entangled system prevents FTL communications. I recently read a book 'Cracking the Cosmic Code' which actually shows that the randomness is not a restriction at all. It now opens up the distinct possibilities of FTL communications.
Sorry but you explained this poorly. All you had to say was if Alice wants to send a 1 and she FORCES her particle to be 1, then entanglement is broken(no info sent). However, if she simply MEASURES her particle and it is a 1 then she knows Bob's will instantly be 0. This is still not sharing information though, because Alice cant choose what to send(if she does choose entanglement is broken).
Can you tell when the entanglement is broken?
What if Alice tries to destroy her particle?
What if she throws it into a BlackHole, or splits it, or vacuum collapse happens in her part of the universe?
Nothing happens
@@tedarcher9120 You mean as in Bob would still end up with a random state?
Кирлджифук Стан yes
Same thing
correct me if im wrong but isnt it impossible to destroy quantum information?
What about using (time) of a state change to communicate a 1 or 0 ? Like a Morris code in binary.
That is my very question I've been trying to understand
I always thought that, well ok, you can't send a message faster than the speed of light. But, we're not considering that there is one information being transferred faster than the speed of light the moment the second particle is measured. So, this is not an information?how about we make a sequence of measurements, or interactions with a given time for each measurements of the first spin particle, so that the second one is responding, we don't mind about the direction we're seeing, we only use the time gaps between the measurements to make a binary understanding, zeros and ones. If we know when a particle is measured, and we know that his sister is flipping at the same time, we can send information like Morse code. This makes sense somehow? That was my thoughts as well.
Then an user responded that entanglement causes correlation but it doesn't cause causation. Absolutely no information Is being transferred in entangled wave functions.
Great video as always! Did you get your PhD in the end? :)
I'm doing my PhD now :) How's your career going?
I enjoy your series of videos immensely and especially appreciate your willingness to ask questions.
Regarding FTL communication, please consider measuring electron and positron spin states where Alice measures angle A and Bob chooses either angle A or B in order to send a yes/no response. If Bob measures A then if Alice re-measures A she is assured to measure the same result of up or down again. If Bob measures B and Alice re-measures A than the state renormalizes and may or may not measure the same result. Therefore if this is repeated enough times, than Alice receives a response that becomes more definitive with the number of trials.
Regarding entanglement used for sharing encryption keys. Believe it or not sharing encryption keys securely, is very difficult to do without actually meeting. If we were to stream entangled particles to Alice and Bob and they always made the same measurements, then they would each be receiving binary strings only with opposite values such as 100110111 and 011001000 which is exactly how differential pairs in high speed digital communication works, only we keep the pairs together and read their differences.
In any case simply agreeing before hand or using a standard of which string to use, then two people could share an absolutely secure private encryption key which could be used to both encrypt and decrypt messages.
Note that this eliminates the need for a trusted third party to manage public keys.
I love how we still insist we can and can't do things when we have the relative understanding of physics of a toddler.
If you wanna go find where FTL information can be transferred, you're welcome to try, but as of now, all signs point to no.
@@noahbaden90 The point is we haven't seen enough signs to know either way, and most signs we've encountered are in the context of not understanding the relationship between QM and GR
No one's claiming that our current understanding of quantum mechanics is objective. These are speculations based on rigorous testing and theory.
@@bleach.princess 'rigorous'
Laugh my ass off reading this comment humans might as well be ignorant with limited understanding of what's going on lmao.
I hate it when someone says you cant do this or this cannot be done. Instead of saying that say "we have not found a way yet".
The problem with saying "we have not found a way yet" is that it implies that there is a way in the first place, a way to be found. And that may not even be the case. Some things may be a technological achievement ahead of us, but others may indeed be impossible (in the full meaning of the word), not everything is dependent of technological advancement. The best way to phrase it would be "we don't know if there is a way", because that clarifies that there might not be a way at all, but also leaves the door open for a way that we may not know that exists.
This is the best video on exactly this topic I found almost instantly, from our speed of perception. Great work, Thanks!
It raised 2 questions in my mind. 1 = Is it possible that we have simply not done enough experiments on Quantum Entanglement to see a pattern emerge, and don't see a pattern simply through our lack of enough research, extra factors etc.
2 = can multiple particles be Entangled? Can entangled particles be further entangled? Can pairs of entangled particles exist?
OMG you are back !!!!
How is your Ph.D. going?
Great! :D (Except when I secretly take days off to edit RUclips videos...)
Thanks for asking!
Looking Glass Universe Haha, I know exactly what you mean! I snuck in my Geometric Algebra tutorial video while my PhD advisor was traveling ;)
Looking Glass Universe you're going for a PhD kun physics i assume ?
That's the way isn't it? But actually most of the time my supervisor doesn't seem to notice whether I've been in or not. A bit sad!
Yes, in quantum computing.
What if you don't have to measure the state of the particle, just if it changed?
If you have two pairs, you can get 1 bit of info out of them.
You only need to check if the state of the particles has changed; if only one pair changes, that is logical 0, if two pairs change that is logical 1.
Sorry, if I didn't understand you correctly, and for any grammar mistakes I made.
that is also what I'm thinking
From Looking Glass Universe: "The issue is that originally your state is an entangled, and *the measurement destroys the entanglement* [...]. What I mean is the state of Alice’s electron afterward is no longer related to Bob’s at all. So she can measure it all she wants now, it won’t tell her anything about Bob’s side.
Nice explanation.
Does that mean, entangled particles behave like pseudo random number generators with the same seed?
The results are the same at both positions but you can't manipulate the outcome of one to alter the state of the other.
Some time ago (maybe a few years ago) you asked for feedback about the videos and tutorials you uploaded. I'm a little late to the game, but please don't change anything. I love them just the way they are. You have a knack of being able to explain the most difficult concepts in a way they are easily understandable. I found your channel when I was looking for something on the Heisenberg Uncertainty Principle. Really excellent. I shared it on Facebook and made a recommendation for others to watch it. Looking forward to the new ones.
Thank you so so much, that's so kind! Really, thank you! I'm so glad you like my explanation.
By the way, was that the HUP video I made recently or a few years ago? Because the recent one was a bit of an experiment where I tried to make the idea understandable for someone who didn't already know quantum mechanics. I have no idea if it actually was though.
It was the one done on Sept 9, 2016. "What Heisenberg's Uncertainty Principle *Actually* Means." Really liked it. I'm slowly working through all your videos on QM.
Like most people, I readily admit to struggling to master all the concepts, but I can't see why the 'pause of "n" seconds to confirm the previous observation sent the desired orientation'; while a 'pause of "x" ' confirms the previous observation should be ignored', wouldn't work as a ftl method of communication, assuming that Bob and Alice have a ready supply of entangled particles to use as a combination of coding and confirmation pairs? There is an assumption they can determine when one of them has observed a particle, and which particle was observed. Just for clarity's sake, to give a non-quantum equivalent example, Bob wan'ts to tell Alice to do something by flipping a coin showing heads. Bob sits in a room flipping a coin. There can be no communication between them, other than Alice knows that Bob is flipping a coin (this can be achieved by agreeing a time when he starts flipping), and if Bob has flipped a head or tail, and can measure how often he flips a coin. Say Bob flips a tail, he waits 5 seconds and flips again. Alice knows he flipped a tail and he then flipped again 5 seconds later, so she ignore the tails result. Eventually Bob will flip a head, and he only waits one second before flipping again. Alice now knows Bob has both flipped a head and flipped again one second later and therefore knows that Bob's message is 'heads'.
I keep thinking about this stuff. What I am getting at is that if the two particles are entangled, which I assume acts as if they are connected with a two way cause and effect relationship. If that is case, why can't they set up a series of multiple consecutive observations, where they would agree to change at during those intervals and you could record changes on either end.
Now if I were flashing a light at you, how would you know it wasn't just random flashes of light? The first you might assume is random, second and third also. If I am flashing a pattern (like a morse code) with multiple observations on the other end you would have a good idea that it was an intelligible pattern and unlikely random.
If the two people have a prior understanding that they will check every so often for a change. A message will have a non random preamble so the other will know when to start making repeated periodic observations, where message starts.
If computers and cameras were used you could make a an automated process for fairly complex communication.
I doubt the answer could be so easy, so what is the catch?
From Looking Glass Universe: "The issue is that originally your state is an entangled, and *the measurement destroys the entanglement* [...]. What I mean is the state of Alice’s electron afterward is no longer related to Bob’s at all. So she can measure it all she wants now, it won’t tell her anything about Bob’s side.
I think the problem is the nature of language itself. It should be possible to construct a device or packet of information
that exists in a balanced state of unity. One requirement for this
involves actually knowing what blocks of information and energy are, and
how they dovetail with each other in a comprehensive sense. Mathematics
may be helpful in this endeavor. Imagine that the building blocks of
energy/info, once combined into an aggregate, can lead to a coherent,
interconnected state that is tapped into unity. All blocks of
energy/info must cancel out to a unified state. It is a bit like
assembling an advanced puzzle. It would be beneficial to be able to plot
the progress of the puzzle, using mathematics, because the pieces would
manifest dynamic energies when brought into contact or correlation with
one another. Creating a balanced puzzle state would enable
instantaneous communication, using nullified blocks of energy/info for
transmission. The unified, timeless realm would be the conduit. The
dualistic nature of language is thus the barrier that must be breached,
when elements are brought into harmony and unified, the conduit to unity
is revealed. Hemingway said: "write the truest sentence you know". Did
he sense that there is an underlying truth within the words themselves?
What would a true, unified statement look like?
great comment
Hold this cup, my brain is about to explode.
The last part of the video is telling. Not for faster than light communication, but for work done involving examining both particles using regular light communication combined with the quantum instant correlation, we can set up a working encryption system between the 2 particles that cannot be intercepted nor manipulated even using another signal that travels at the speed of light. Because the encryption formula requires something from quantum entanglement needed to be combined with something else that needs to travel the distance at not faster than light , to effectively complete the encryption …and not one without the other. Am I correct?
With something known from each particle, there is a complete circuit, and that thing known from the second particle is only obtainable by measuring the first particle too. This means part of the link is tied to the quantum entanglement.
If just measure particle 1, no new knowledge regardless if particle 2 measured not by you
If just measure particle 2, no new knowledge regardless if particle 1 measured not by you
If particle 1 and particle 2 are measured in an agreed upon way, then something is learned, something which no other outside force can manipulate the correlations between particle 1 and particle 2, correlations which are unique only to those 2 particles, correlations that are not coded prior to measurement nor is there any light delay in the correlation at collapse, but which requires access to both particles to complete the puzzle.
So it's not about the speed of light at all. It's just that the entangled particles move randomly. Is it possible for Alice to measure once for yes and twice for no?
It will be possible with time. I love reading articles of scientist stating impossibilities in the past and then reading the debunking articles later on. Our recent advancements in the understanding of quantum mechanics has me very optimistic about the viability of quantum communications in our future. There have been many gatherings of world famous scientists in the past that have come together and decided that we have discovered and invented everything we can and that our efforts beyond that point would yield no useful results. I've seen articles of theoretical limits on quantum entangled particles that we debunk VERY soon after publication. I hope there are teams out there with a higher understanding that share my optimism for our future in quantum mechanics.
You realize that faster-than-light communication, if possible, would immediately allow sending messages from future to the past? It's a direct application of special relativity.
I don't quite get why you cannot do the double slit experiment to see if the red particle acts like a particle or a wave. Isn't that whay they did in the delayed double slit experiement? They checked the particles one after another and they got different results when the entangled particle was detected (1st particle acts like a particle) and erased (1st particle acts like a wave).
Ditto. LGU floated that option as 'clever' at 01:12 but didn't address it. Plz someone explain why a long distance 'Delayed Choice Double Slit' style arrangement wouldn't enable Bob to tell whether Alice had chosen to collapse her particle or not and thereby communicate Y/N?
But this is just for 2 entangled particles.. What if they have 3 entangled particles and Alice takes one and Bob has 2.. Then if Alice breaks her superposition, Bob has 2 entangled particles to check if they are in superposition...
when you entangle two particles (A & B) and then entangle a third (C) with B, A instantly teleports or becomes C and B & C disappear. can't we use that to communicate like you just have to have Alice entangle one of two sets that bob has with a particle that she has
did you ever create a follow up video on "one-time pad"? I didnt see one
Hey, first of all, I love your videos! Keep up the good work!
I have two questions, one of which a more general question but the other more related to this video:
1. In all your videos, it seems that the main argument for as to why a superposition of states is different than not having previous knowledge of the state, is the interference pattern created by the double slit experiment. I wonder if there are other experiments in which the quantum weirdness of superposition and measurement problem become apparent.
2. In this video, you state that there is no way Bob can know whether Alice measured or not, and thus information is not travelled instantly. However, this argument just shows that there is no way Bob can gather / read the information, but according to entanglement, "universe-information" still travels faster than light (in other words, there is still information traveling faster than light, but there is no way for us humans to detect it). Is there a way around this, or do we just have to accept it and live on with our lives? Measurement problem is weird...
What if she measures her particle until it's the answer she wants to give, then an automated system checks the other particle 1,000,000,000,000,000,000,000,000,000,000,000,000 times over to make it very unlikely that the particle isn't just repeating by chance, to determine the response? And use that like binary to transmit complex information over a very long distance. Or do the particles no longer change after their first observation?
From Looking Glass Universe: "The issue is that originally your state is an entangled, and *the measurement destroys the entanglement* [...]. What I mean is the state of Alice’s electron afterward is no longer related to Bob’s at all. So she can measure it all she wants now, it won’t tell her anything about Bob’s side."
What if you have a big mass of particles and kind of entangle it in morse code intervals, could someone on the other end measure the time in between obervations?
Short answer: no
@@theendofthestart8179 dammit xD
can you not tell if a particle is in a super position if you kept closing the box and looking back? if the other person is measuring their particle wouldn't it stay in the same state? say you made a system where the entangled particle was kept in a super position for 2 seconds for a 1 and 1 second for a 0 while the other was measured 1000 times a second by a computer to see when the position changes to create some kind of Morse code?
From Looking Glass Universe: "The issue is that originally your state is an entangled, and *the measurement destroys the entanglement* [...]. What I mean is the state of Alice’s electron afterward is no longer related to Bob’s at all. So she can measure it all she wants now, it won’t tell her anything about Bob’s side."
I'm confused because I can think of a scenario where this would work that wasn't addressed.
What if Alice and Bob each have a pair of entangled particles. The first would be to receive a message and the second would be to send a message. They agree that at a specific time of day (assuming they are on the same tine) Alice will send a message and Bob will as well. They will wait a certain amount of time to avoid a mistake and then each will check for a message. This is assuming that either alice or bob can forcibly make the particle have a desired measurement.
Wouldn't that qualify? And if no then why not?
Also forgot this, they have agreed before hand that they will only measure up and down spin.
Never mind I just read that for particles to be entangled you have to ask what state are you in, if you force it you break entanglement
I have this idea that they could communicate FTL. Please comment if you know why not. Now: Futuristic set, with intergalactic travel happening. Alice is being persecuted, and wants to hide in a planet, she has two available options, planet 1 or 2. She uses a quantum collapse to choose which of the two in order to make the decision totally random so that no one can predict where she has chosen to hide. She doesn't choose which one, but the collapse of her particle does (if spin down, she goes to planet 1, and vice versa), Bob is on another place in the galaxy and they had agree that on X moment(*), Alice will have the planet to hide decided by collapsing her particle, So then Bob can know FTL where Alice is heading, and hiding. (?)
(*)day-minutes, or whatever precision is necessary so that Bob can know the planet FTL
What if there were two quantum particles instead of 1 and if one represented 1 and the other 0 than it wouldnt matter the the answer is randomized, all that matters is what particle was used right?
How would you know which particle was used/unused?
Thanks for the video! I'm always waiting for them :)
I'm so sorry to make you wait for 2 months but I really do appreciate that you came back!
Hi. Surely Alice CAN communicate with Bob simply by choosing to -
A) collapse her particle or
B) Not collapse it.
If A) then its photo=electric signature will be detected in one of TWO predetermined bands. If not collapsed it will detected in one of SEVERAL predetermined bands synonymous with an interference pattern. So just fire a 100 entangled particles in quick succession and have Bob check if they sum to an interference pattern or not. Granted there's still a minuscule chance off an unlucky miscommunication but the odds would massively favor Bob correctly reading Alice's intent.
it is explained in the video why bob cannot "see" if its particle has collapsed: regardless of the state of Alice's particle (and hence his), its measurement would be random with same probabilities
Can we change the state of entangled particles? If we can, does the entangled particles still entangled? This can be another way to communicate. That's probably impossible or too hard to do.
Note: I have little/no knowledge of quantum physics.
Well, for one, when you intercept the "one time pad" assuming you had figured out how to do that, you collapse the wave function because you observed and interested with the article in some manner. if your detectors aren't aligned exactly the same as the detectors Bob has, then the one time pad message Bob receives will be completely different from what you saw. so when Bob sends the confirmation of the pad, Alice's computer and Bob's computer, after some comparison of notes, can tell if someone is hacked in.
on top of all this, since the detector alignment is never included, the middle Man (the Queen of hearts, obviously) cannot know for certain if her detectors are properly arranged.
for example, if you had three possible alignment possibilities, the Queen cannot know if the correct answer is a left/right detection, a back/forth detection, or an up/down detection. she only knows which detectors were identified as incorrect, but not the why. without knowing the why, she can't guess at what happened. was her detection using the same set of alignments he did?
without knowing that, which would require some sort of obtrusive observation of the target computer, she is not knowing if her information is accurate
What if we use morse code and use the intervals between the changes to communicate?
You can't know if the particle has changed until you measure it yourself. So you can't know the intervals.
I agree that entanglement does not allow for faster-than-light communication. But what it does show, clearly, is a phenomena that appears to violate special relativity. Physicists address this issue with a lot of hand waving - but never seem to get to the root. Locality is not what we think it is. I suspect that two entangled particles are local to each other all the time - but in some unseen dimension. Perhaps the particles exist in quantized spacetime, and as such, the spacetime itself is entangled in higher or different dimensions that we do not see directly.
You're videos are amazing! As an engineer it is super interesting and makes me think outside of the only realistic and useful applications
knowing that one particle is ether up or doun is information. pre deturmined questions about what one person will or wont do at a given time should be able to be answerd if both are accurate about the time of mesurement.
Hi, I am no physicist by any means, but I love your videos. It's very nice to see explanations that are `striped down' and (more than usual) concrete. Thanks a lot, and please keep this going.
When Alice measures the state, bob can do the same but a few times. If the state will be always the same, it means that Alice is measuring the state. When she stops bob will get random values. That means that Alice stopped to measure. These two situatuons can be interpreted as 0 and 1. Where am i wrong?
Now i know. When Alice do the measurement the quantum entanglement will be destroyed. It means that you can measure it only once.
Why not just use it as a signal rather than complex communication? Let’s say the entanglement is isolated in a specific channel, with a specific message pre written, then when the particles fall into a spin that’s when the signal is detected, then it triggers the message pre written. Examples could include to return, someone found X, etc.
Based on our current understanding it would be impossible, but I'm not convinced we understand quantum physics all that well or have even scratched the surface of that world.
What about if Alice and Bob start off in the same room and conduct a series of double slit experiments, they run the experiments and record the data that shows which slit the particle went through and also what pattern it made (interference pattern or not). They don't look at the data. They then part ways and Bob begins his journey across the universe with all the data that shows just the patterns and Alice keeps the data that shows which slit it went through. Alice can then communicate with Bob faster than light, a message by selectively deleting the particle path information before she has viewed it, which Bob can then look at and see either interference pattern or not.
Quantum entanglement + twins aging relativity experiment --> ???
Entangle. Separate. Subject to different time flows. ???
Also this: curiosity.com/topics/entangled-quantum-particles-can-communicate-through-time-curiosity/
Your videos are amazing! Hope you can upload some videos about thermodynamics someday lol
What I believe that is actually going on, is that there is in fact a medium in which light travels - and that medium inhibits light to travel faster than it does - but down at the quantum level the influence of that medium (this medium could even be spacetime itself) doesn't inhibit that... But even though you can send the information faster than light - when you try to read it - the whole thing becomes macrostate (because you are a macrostate person) and thus, you read only jibberish...
I still don't quite understand.
So what you are saying is that an entangled particle can't interfere with "itself"?
So if Bob does a 2 slid experiment, where the particle goes left if spin UP or right if spin DOWN, it wouldn't create an interference patern (when alice doesnt check)?
These videos are so great! I've wondered about this one for a long time.
I'm so happy to hear this cleared it up for you!
What doesn't make sense to me is how has it been demonstrated that entangled particles are affected instantly at any distance if the only way to see the effect is to measure them at the same time and in the same place?? Does it mean that if I measure only one of them I break the entanglement?
Nicely updated! Since it looks like your research is in quantum computation, it would be cool if you popularized the programme of decoherence (the word "collapse" is taboo for you guys). It also makes the general solution to that homework problem nice and neat.
Thank you. Was looking for a video explaining if the other option was impossible. So if I understand it correctly, entangled particles, without their partner, will never produce an interference pattern on the double slit?
Even if we are not sharing the spooky Quantum paradigme presented in your video, remains that your videos are Amazingly Well Presented and Clear; Very Well Done for that! :)
Fellow science community.. don't observe this video as a statement of impossibility, we'll always find a way to put nature under our own favour so think logically, briefly mathematically because that's where you'll find the flaws besides, creativity is highly appreciated.
PLEASE explain why it isn't better to discuss Alice & Bob experiments using simple Photon Polarity (a 2D binary variable) rather than more complex Particle Spin (a 3D binary variable)? After all the original EPR used entangled Photons and Polarized Lenses (ie: Sunglasses) as (A)(B) Detectors which is easier to visualize and less mathematically challenging yet equally applicable to demonstrate entanglement mechanics?
It's always a pleasure to see a new video from you.
By the way, I never knew the Mad Hatter's name was Bob; I always thought of him as Bertie.
Oh no, definitely a 'Bob'!
Ha! Nice to hear from you too. Sorry about the absence...
Thank you. And you have nothing to apologize for; your studies come first.
I still say the Hatter should be Bertie, because of his uncanny resemblance to Bertrand Russell: www.google.com/search?q=bertrand+russell+mad+hatter&newwindow=1&tbm=isch&imgil=BbRELLThhK1w1M%253A%253Bvs6FIaq8fOPssM%253Bhttp%25253A%25252F%25252Fglassbottomblog.blogspot.com%25252F2011%25252F08%25252Fnonrepresentationalism.html&source=iu&pf=m&fir=BbRELLThhK1w1M%253A%252Cvs6FIaq8fOPssM%252C_&usg=__R1k12yowobq-iXNGb4rGbdNLgqU%3D&biw=1231&bih=614&ved=0ahUKEwjrpubV-97TAhUB3yYKHUWiChwQyjcINg&ei=zLEPWeuQCoG-mwHFxKrgAQ#imgrc=BbRELLThhK1w1M:
Watching the video again, I notice that you already knew about the Hatter and Russell. Sorry.
Aahhahaha! No I didn't! That's very funny!
But you had the Hatter using Russell's Paradox. That is a truly amazing coincidence, then.
God essentially saying "lol Not so fast, silly humans."
If you referring to an imaginary friend, then yes
Great... again God, that human creation that obliterates all common sense
Have you produced the video on communication you were refering to in the end of this video ? Fantastic work by the way !
Do states with 3+ entangled particle exist, and are they different in a meaningful way? i.e. can you use two of them to see if the third has been observed? (I assume the answers will be "yes, no" respectively)
also: I love the channel, even if you never upload ;)
They exist! But yes the answers are yes and then no. Yes because weird things happen when you have three entangled particles. There's no longer an idea of the 'most' entangled states. See in the 2 particle case, if you start with the most entangled states, Alice and Bob can separately do stuff to get any other 2 particle state between them. This is no longer possible with 3 particles.
Actually 3,4,5 particle entangled states are all topics of very active research!
You cannot induce an up or down state with regularity?
I thought we could, because if we cant then how can we be 100 percent certain that entanglement is there
@@balbuena1225 We can make entanglement measurements through what is referred to as an Entanglement Witness; these are observables which when measured can with certainty determine the state of entanglement(as well as the type). Beyond this very high level description we start to use some complex science and math speak.
I have a question: is a particle's measured state actually random, or only _in effect_ random, i.e. decided by processes we cannot (currently or perhaps ever) measure? Might our measurement determine a particle's state by some deterministic process invisible to us? Do we know for sure that state is random, and if not, do we know for sure that we can't know for sure?
i love your videos. thanks for being such a great communicator..
It appears that Time is the dilemma. Measuring takes time, determining Yes or No, right or left, up or down. That's dualistic thinking. For unity there is no differentiation of different states, all are commingled. Entanglement of two particles is a form of unity. If communication takes time, it is bound to causality. Outside of time, instantaneous communication may still be feasible. However, it would not operate according to our rules of language. A communication might work with new language rules enacted, or by sending unified messages that do not split into right/left, up/down etc. A Non-dualistic system.
This was an awesome and very accurate video. Few days back, I was thrown this question of faster than light communication using entanglement and I was thinking on how to refute it. Funny thing is that I had got exactly the same ideas. Except, on the second case, I did not use math but went about it conceptually and by visualization.
Awesome! That's really cool you worked it out for yourself :)
Same! I guess great minds think alike
We simply dont know how to use it. What is for sure is that one particle sends an impulse to the second one faster than light.
What if Bob could change the spin of his particle? Alice's particle would change while she is measuring. Then continuously "up, down, left and right" could mean: "yes". And "down or up": "no".
Scientists already know how to change the rotation of entangled particles?
Another point, if alice and bob have a huge amount of entangled particles, why couldn't Bob do a double slit, to check if Alice meassured them all? I don't think you went into detail about that, but I will rewatch.
As in .. why can't you get interference from entangled partickes? Is that just some silly rule they made, or has it been tested?
Physics does not contain any made-up silly rules. It may appear that it does if you can't follow the math, but it doesn't.
Michael Sommers
That's what I mean. I am not satriesfied with some mathematical brush up. I need actual hands on studies.
Then you have several years of hard study ahead of you. Without a substantial background in physics and math, it is unlikely that anyone will understand original research papers. Here, for example, is a paper by Bell on EPR: libertesphilosophica.info/blog/wp-content/uploads/2016/11/Bell-1964.pdf
Michael Sommers
Thank you. The problem with a mathematical proof, is not that I doubt they can do the math. The problem is, that our understanding of physics have to be correct. I understand, that for a vast majority of real life problems, physics seems to work. However, when it comes to these things, people tend to just brush it off with math and refer to basic physical laws.
What if we combine Quantum Entanglement with the Reverse time quantum experiment. Could that be used to eliminate the interference caused by the measurement? I send a message by changing the state of Particle A. Particle B is immediately effected due to entanglement with Particle A. You measure state of Particle B and run Reverse time experiment against Particle B simultaneously. You measure the state while time is reversed for the particle. Now you can decipher my message. Plausible or am I way off?
curiosity.com/topics/entangled-quantum-particles-can-communicate-through-time-curiosity/
I have a question. I should say that I only have what would be charitably called a lay person's understanding here so I apologize if this is an ignorant question , but I've heard that if you have three particles A, B, and C, that you can entangle A and B, then B and C. And that after performing this series of entanglements all three particles are entangled together. I understand (I think) why you couldn't perform an interference test if you only had access to one of two entangled particles. But if Alice holds particle A and Bob gets particle B, then entangles it with particle C, could he not perform an interference test with B and C to determine if Alice had measured particle A?
So we have to focus on predicting and influencing our own measurement. Is there some law that makes it impossible to do this?
Can't they use like the telegraph approach to communicate? Let's say they have lots and lots of entangled particles, Alice measures particles at an interval of 1second and 2 seconds a dot and a dash respectively, Bob would see the particles on his side repeating the time intervals. This could be the basis for communication no?
If we try to do a computer simulation of this behaviour by solving big systems of differential equations, then we need to be able to shift information faster than light. On the other hand, that information is useless for superluminal communication. It is in the nature of a one-time pad rather than a book, and the pad cannot be be accompanied by a second one-time pad such that there is a message hidden in the joint correlation between the two pads. It might look as if we are trying to tackle something extremely difficult with no reward. I'll just suggest why the situation is not as bad as it looks.
Modification of the Schroedinger equation is prohibited. It is known to be accurate to one part in 10^12 at the ensemble level, and there is no evidence of any need for modification at that level. Richard Feynman talked about a terrible straitjacket, and indeed that is what we appear to be trapped in. I would just suggest that this is exactly so at the ensemble level. At that level, the existing theory of quantum mechanics is complete.
At the level of the discrete event, we know from Bell's Theorem that we need to be looking at superluminal activity. A little playing around with the Minkowski formalism indicates that there is more than one way to travel faster than light (I don't think I am the first to notice this). I would suggest that the Schroedinger equation or its offshoots describes an oscillation in one of the ways, and we can have tachyonic Brownian motion in the other way, taking us out of that straitjacket in a direction which is orthogonal. This is an idea for computer simulation which makes use of a random number generator, and there is a long way to go towards implementing it. If anyone want to suggest some other way to use a RNG, then be aware of that basic rule about not modifying the Schroedinger equation.
Alongside tachyonic Brownian motion in the Schroedinger equation we can have co-ordinated TBM in the electromagnetic field. The nonlinear interaction between two fields is able to shift information nonlocally like a natural Vernam cipher. Causality is not an issue because this is uncontrollable random activity and causality is merely an anthropocentric concept. A Lorentz transformation can exchange apparent cause and apparent effect. So what? By the time we do a real Lorentz transformation, as opposed to the metaphysical Lorentz transformation that we might think we can do, the random event under study is ancient history.
So superluminal communication is impossible, but something is travelling faster than light and what it is does not necessarily lie beyond our imagination.
I do not know anything about quantum physics.
…Howeverrr… couldn’t you have two entangled particles (A has the same output as B when either is observed), put one aside for control (A) and have the other one (B) randomly checked constantly? So, every time B is checked, it collapses into a random probability, and the chances of it being the same one multiple times in a row is very low? Therefore, if you measure A, B will remain in a single possibility for as long as you observe A, and no matter how many times you check B it will stay the same? Then, you could just check wether or not B is changing, right?
You explained this very well, thanks for making this.
Quantum entanglement does not allow useful information to travel faster than light. But what if the transmission of entangled particles were time modulated so that their 'states' didn't convey the information but rather the manner in which the entangled particles were produced? In other words information could be encoded into the random entanglement states using time packets. This might work as a form of quantum Morse Code in which the change in states of entangled particles over time conveys the information, not the random pattern of the states themselves.
Last video you said, that if one of the particles has a spin up, another one has to have spin down, but now you are talking about left and rightness. You're saying that even if the electron has spin up, the positron has the same probability for spin left and right. But why do we even care about left and right, when we can always measure only ether it up or down. This is the thing I don't understand. Do I make any sense right now?
This is actually super spooky. Because it's worse than instantaneous action between particles. If you consider special relativity, for some observers Alice opens the box before Bob does, and for others, Bob opens it first. So it's not like the "truth" is that Alice opens it first and Bob's particle's wavefunction collapses to a spin eigenstate that you simply can't distinguish from the entangled state. They are absolutely indistinguishable because, for some observers, it's Bob the one who measures his particle first, collapsing Alice's particle's wavefunction. And none of those two perspectives should be "truer" than the other. You can't say that either one of the particles is affecting the other. The particles don't just act on each other instantly; they conspire in a way that permeates the entire fabric of spacetime xD. There's an eerie symmetry right there. Man, we live in a simulation.
Last video you you said, that if one of the particles has a spin up, another one has to have spin down, but now you are talking about left and rightness. You're saying that even if the electron has spin up, the positron has the same probability for spin left and right. But why do we even care about left and right, when we can always measure only ether it up or down. This is the thing I don't understand. Do I make any sense right now?
Can't the receiver check once every second the state of his particle and the sender to send the message collapse the particle state until it becomes the bit he wants to send in that second?
For example if I want to send the message 1010, I can make the particle collapse multiple times until it becomes 1 before t is 1 (t is time), then I make it collapse until it becomes 0 before t is 2...
Now that is a pretty cool way to explain it, well done!
1:50 - 2:30 ..so you need to measure both of the particles together? I must be confused because the delayed choice quantum eraser measures at different detectors at different points in time.
Can't she use an aligned magnetic field to force an 'up' spin - this makes the other side 'down' ?
this video is nonsense lol. you most certainly can.
@@texasfossilguy No I later found that an aligned magnetic field will only align spin. It can still be 50-50 up or down in that alignment. Basically we can't simply force an 'up' result on one end
False premises. Alice is not merely producing random electron particles from her brain but from a specific region that is supposedly entangled with Bob's specific region. Thus, Alice can indeed influence Bob's electrons by merely thinking about something in Bob's specific region. That is how FMRI machines now can read human thoughts as seen on 60 Minutes.
But can we figure out if a particle is being broke out of superposition without looking at it?
The issue I have here is that quantum cryptography says you can detect this measurement by an Eve, but here, you echo textbooks about entanglement that say you CAN'T detect it. I don't know which it is but one or the other assertions is false.
The trick here, I suppose, is that you have to split Alice's quantum cryptography photon through a spool of fiber optic cable so that it can be snooped on by Eve in the same lab as Alice to send the "Eve read it or not" message.
Why not just keep measuring, then putting it back into a superposition until it's the state you want, and then wait until the other person (or computer) assumes you're done measuring and checks to see the answer?
I have an idea: The instant there is a state collapse of any kind, it would equal a "1", and each following millisecond (or any agreed upon time interval) that ticks by would equal a "0". When another state collapse occurs, it'd equal a "1" and so on.
Hi,
Thanks for this great explanation, I've always been interested in possible applications of QM for communication. I'd like to ask, what if Alice has one particle that is entangled with 2 others particles that are with Bob? (I do speak about 3 particles entangled together) Should that allow Bob's particle do produce interferences if they are tested together? Or as long as one of the particle of the entangled system is not there, no interferences will be produced??
Wait I thought if you measure the photon in one direction, say vertically, the outcome could only be up/down spin. Otherwise it could be up/down or left right.
Can't you just make up/down = yes,
left/right= no?
there are 3 states measured, unmeasured and both
What if Alice's intentions are aligned with the entangled particle on her side, she would be able to influence it in her favor. Thus, she would be able to communicate effectively over vast distances, given the scenario. I know this sounds like mind over matter, but it may be possible, entrainment can happen, that's what quantum entanglement proves. If one ceases to treat particle as object, and measurer as subject, object and subject become one. Alice's mind and particle are no longer divided, they become indistinguishable. You may say, "the particle's fate is random, and cannot be influenced directly through Alice's intentions". Okay, that's fair enough. But what is randomness? Randomness is a measurement of how one's guesses run contrary to one's outcomes. With a coin toss, accuracy of guesses are roughly 50/50, based on chance. 50% of guesses are misaligned, or anti-aligned. If so, it is fair to give randomness its due 50%. So, in a given coin toss, 50% of guesses will be wrong, or misaligned. But what if randomness is just a measure of misalignment? Is there a way to locate a confluence that exists after misalignment and alignment come into parity? A place of unity? Perhaps intentions could be sent through this balanced confluence, so that the influence of time is negated. Randomness is thus taken into account as a force, a force of misaligned energy. A Yang energy, in fact. So, I am suggesting a third element in this scenario, either the mind of Alice, which connects directly with the particle, or a machine that can find confluences where unity applies, then is able to send intentions directly to the particle at certain intervals. If there are confluence points that are accessible, "timeless junctures", then this experiment could function properly, once all three elements are combined to operate as a seamless entity. Unity is about balance, and when misalignment is balanced with alignment, timeless gates may open. These gates bypass causality, where we are stuck due to the effect of Time, Entropy, and Space.
I had serious question boggling me from a long time
if many worlds interpretation was true then each event in a superposition will surely occur in one of the universes so we should instead of saying that each microstate is equally likely to occur we should actually say that our measurement resulting in either microstate is equally likely .Is there something related to this or it is just a verbal error. what's even the point of wave function if we know the events are surely going to occur in one of the universe .
Great questions about many worlds, that have been raised by people. So many worlds believers have attempted to answer these and when I feel I understand those answers I will certainly make videos about them!
Looking Glass Universe in your video on Heisenberg uncertainity you just proved that del x and del p are inveresely propotionate why is there an inequality there insted of equality also why must the constant of propotionality must equal h/2pi
I think the constant is really just to do with units. But it's an inequality because it can be worse than that. A particle can have very badly defined position and momentum.
Looking Glass Universe what's worse than inequality ; no relations ?
Looking Glass Universe also can there be some kind of planck unit for uncertainity
What if Alice observes particles and pauses for a predefined amount of time, when the result she observes is the one she wants
Bob to note? So a 1 second pause means note this particle, and a 0.5 second pause means ignore it. Like Morse code.
I just realized there is no way to introduce a pause. :) Oh well.
I like how you're thinking- and even that you figured it out yourself!
@@LookingGlassUniverse Like most people, I readily admit to struggling to master all the concepts, but I can't see why the 'pause of "n" to confirm the previous observation sent the desired orientation'; while a 'pause of "x" ' confirms the previous observation should be ignored', wouldn't work as a ftl method of communication, assuming that Bob and Alice have a ready supply of entangled particles to use as a combination of coding and confirmation pairs? There is an assumption they can determine when one of them has observed a particle, and which particle was observed. Just for clarity's sake, to give a non-quantum equivalent example, Bob wan'ts to tell Alice to do something by telling her he has flipped heads on a coin. Bob sits in a room flipping a coin repeatedly. There can be no communication between them, other than Alice knows if Bob has flipped a head or tail, and can measure how often he flips a coin. Say Bob flips a tail, he waits 5 seconds and flips again. Alice knows he flipped a tail and he then flipped again 5 seconds later, so she ignore this result. Eventually Bob will flip a head, and he only waits one second before flipping again. Alice now knows Bob has both flipped a head and flipped again one second later and therefore knows that Bob's message is 'heads'.