Does Quantum Entanglement Allow for Faster-Than-Light Communication?

Quantum entanglement allows particles to affect one another faster than the speed of light. So does this mean we could one day build a device to exploit this and enable superluminal communication? A popular trope in sci-fi for sure, but today let's look at the science.

Presented by Prof David Kipping (Columbia). Special thanks to Prof. Ehud Altman (Berkeley), Prof Tim Byrnes (NYU) & Prof. Raquel Queiroz (Columbia) for fact checking our script.

THANK-YOU to our supporters D. Smith, M. Sloan, C. Bottaccini, D. Daughaday, A. Jones, S. Brownlee, N. Kildal, Z. Star, E. West, T. Zajonc, C. Wolfred, L. Skov, G. Benson, A. De Vaal, M. Elliott, B. Daniluk, M. Forbes, S. Vystoropskyi, S. Lee, Z. Danielson, C. Fitzgerald, C. Souter, M. Gillette, T. Jeffcoat, H. Jensen, J. Rockett, N. Fredrickson, D. Holland, E. Hanway, D. Murphree, S. Hannum, T. Donkin, K. Myers, A. Schoen, K. Dabrowski, J. Black, R. Ramezankhani, J. Armstrong, K. Weber, S. Marks, L. Robinson, F. Van Exter, S. Roulier, B. Smith, P. Masterson, R. Sievers, G. Canterbury, J. Kill, J. Cassese, J. Kruger, S. Way, P. Finch, S. Applegate, L. Watson, T. Wheeler, E. Zahnle, N. Gebben, J. Bergman, E. Dessoi, J. Alexander, C. Macdonald, M. Hedlund, P. Kaup, C. Hays, S. Krasner, W. Evans, D. Bansal, J. Curtin, J. Sturm, RAND Corp., I. Attard, M. Donovan, N. Corwin, M. Mangione, K. Howard, L. Deacon, G. Metts, G. Genova, R. Provost, B. Sigurjonsson, G. Fullwood, T. Mitchum, B. Walford, J. Boyd, J. Quayle, & N. De Haan.

::References::

::Further video resources::

::Music::
► Chris Zabriskie - Cylinder Five (2:09)
► Falls - Life in Binary (5:09)
► Falls - Ripley (10:05)
► Chris Zabriskie - Cylinder Four (13:24)
► Chris Zabriskie - The Sun Is Scheduled To Come Out Again Tomorrow (22:20)
► Indive - Trace Correction (28:11)

::Film/TV clips used::
► Moonfall (Lionsgate)
► Passengers (Sony Pictures Releasing)
► Mankind: The Story of All of Us (History Channel)
► Foundation (Apple Inc.)
► Interstellar (Paramount Pictures)
► Contact (Warner Bros.)
► Arrival (Paramount Pictures)
► Back to the Future (Universal Pictures)
► Avatar (20th Century Fox)
► Mass Effect 2 (Bioware)
► The Matrix (Warner Bros.)
► Star Trek: The Next Generation (Paramount Television)
► Star Wars: the Last Jedi (Walt Disney Studios Motion Pictures)
► Genius (National Geographic)
► Star Trek (Paramount Television)
► Star Trek: The Motion Picture (Paramount Pictures)

::Chapters::
00:00 The FTL Dream
02:10 Relativistic FTL?
03:41 Quantum FTL?
06:27 Quantum 101
09:01 FTL Action at Distance
10:33 How to Exploit?
12:23 Idea 1: Repeat Measurements
14:16 Idea 2: Double Slits
18:04 Idea 3: XY Switching
22:20 Where From Here?
28:11 Outro & Credits

#Quantum #ftlfasterthanlight #CoolWorlds

[Schottingham]

I love how many of these videos with a question in the title turn out to be "probably not", because you're clearly not setting out to prove these things wrong; in fact you (and maybe most of us) want the answers to be 'yes', but you seem to really work through the science and find that the evidence is just not there. This is the sort of critical thinking we need to teach.

[DomovoiJr]

Causality dictates that no one has finished this video yet at the moment I’m posting.

[glitcherade]

It's the first time I actually understood entanglement, very well done mate, I always love your way of explaining.

[geogabegalan]

This is a very informative video. Quantum entanglement cannot be used for FTL communication, due to its inherent randomness. But there's another thing worthy of note here.

The consensus is that information and causality don't travel faster than light.

With quantum entanglement, the collapse of the wave function after measuring one particle, is transmitted to its entangled partner much faster than light. But this is not called "information", but "action at a distance".

But information and action have blurred boundaries between them. Every exchange of information involves a physical action. For instance, if I get information through sound waves, the waves have to do the action of vibrating my ear-drums. And if I use my arm to lift a book, I am also sending it the information to alter its spatial co-ordinates.

And it is not said that it travels "faster than light" (well, you said it in the vid, and kudos to you for that, but some others don't), but that its "non-local". It seems to me that these distinct terms for quantum mechanical phenomena only obscure the simple fact that:

We have discovered three speed limits in nature.

1. The speed of sound in any given material, which is the natural speed limit of mechanical waves in that material. Nature has many random sources of sound, like thunder. But we can use sound in a non-random way to communicate.
We also surpassed the speed of sound with supersonic technology and EM waves.

2. The speed of light in the vacuum. This is the natural speed limit for matter/energy travelling relative to the reference-frame of another system of matter/energy, as well as information and causality travelling between systems of matter/energy that are not quantum entangled. Nature has many random sources of EM waves, like lighting. But we also learned to harness EM waves for communication. We also learned to detect random sources of gravitational waves, though we can't harness gravitational waves yet.
The only source of faster then light transfer of information/action that we know of so far is number 3 below.

3. The speed of transmission of information/action at a distance, from one quantum-entangled particle to its partner, to maintain the entanglement at a distance; as well as the collapse of the wave function from a measured particle to its entangled partner. Here, the entangled particles are natural, random sources of...whatever it is that is being transmitted between them to maintain the entanglement.
A classical analogy to quantum entanglement might be acoustic resonance.
An even closer analogy might be the (you can google it, its interesting). Here, the means by which the synchronisation is maintained are:
the "non-local hidden variable" of acoustic waves transmitted from each clock to its partner
through the substrate (say, a wooden beam) to which they are both attached.

If we can identify the "whatever-it-is" that is being sent by entangled particles to each other, to do action at a distance between them, then we can dispense with quantum entanglement, and build a device that uses this "whatever-it-is" to communicate faster than light.

Have you made, or are you planning to make a vid about interpretations of QM that involve non-local hidden variables ("whatever-it-is"), like Bohm's pilot wave, and their possible use (or not) for FTL communication? It would be interesting to hear your take on this.

[mjbarge]

Finally! An explanation I can actually understand. Your ability to communicate very complex ideas in such a clear and understandable way is by far the best I've come across. Keep up the great work!

[BRUXXUS]

I've watched, read, and listened to hours of explanations of why QEC should be impossible, and you effortlessly, finally made it clear. It's so much simpler than I tried understanding that it makes me a little frustrated that it's been so poorly communicated by others.

[robertwcote]

This is really well done, you guys. Great work.

At the beginning you alluded to communications between distant outposts of an interstellar species. This is something I've been wondering about a lot lately and would love to see you discuss it at some point. The main thing I struggle with is the assumption that we would communicate with humans who set out to settle an extrasolar planet. I mean, would we actually? At some distance, the latency would make it almost pointless, right? What sort of information would we share with a colony a light-year away? 10 light-years? 100? It's natural to assume we'd have communications, but when I actually stop to think about it, I'm not so sure anymore.

[RazyMon]

If any interaction with an entangled particle collapses its state, then there's no way for Alice to observe changes without affecting the state of the pair.
In other words, if there's no way to observe (let alone affect) a particle state without collapsing it, this system is pretty useless as a mean of communication.

[a-cv]

Very nice video as always Cool Worlds. I really enjoyed that many scenarios were explored and references to how some of these promising concepts were embraced by popular science fiction as a plausible solution for communication across vast distances.

Something to understand about the current state of quantum mechanics is that the act of measuring is never passive and becomes deterministic of the answer we will get. In most other domains of science our measuring tools manage to have a minimalistic impact on what is being observed. But in the context of quantic mechanics there is no sight, what we try to measure is so small and the way of measuring is throwing particles against the particles we are trying to observe to see how they bounce off.

Perhaps everything will be reconsidered if we find a technology to measure the quantum states without as much interference. I'm already impressed that through statistics of infinitely repeated experiences the quantum mechanics science is able to establish causality when every observation is destructive and deterministic of the state being observed.

I find it interesting to think that anything FTL could however break causality. If we used a theoretical wormhole to send a mere Lightspeed communication through a distortion of the spacetime elevation map, would that be breaking causality ?

The speed of light appears to be in a way the speed of time. Riding a photon, one wouldn't experience time at all. Any particle without mass also seems to be traveling at this speed, and so do gravitational waves. Electromagnetic waves are slightly slower than the speed of light.

It seems like a possibility that the perception of time could be an emerging property of the interaction with the Higgs field. That anything with a mass is dragged through the ever expanding time dimension and able to perceive it, perhaps akin in the same way that gravity holds galaxies together in an otherwise ever expanding spatial universe. Could dark energy be expanding all of spacetime and our perception of time be a mere side effect of gravity on spacetime?

[ag]

We may not have found a FTL communication (yet), but we did find a truly random number generator, i would say!

[jonnyjonjon]

So, I know this will probably never been seen, but what if Bob and Alice have 2 entangled particles. If he wants to say yes, he collapses one of the particles and leaves the other entangled. If he wants to say no, he collapses both particles?

[zx]

There are two identical socks. When you put one of them on your right foot, the other instantaneously turns into "left" sock. This effect does not depend on the distance between the socks. The information about that other sock turning into the "left" one can cross the entire universe in an instant. Woo-hoo! Quantum teleportation at home!

[timrundle-wood]

Another incredibly thought provoking video, thank you so much David for the time you put into them. I believe in miracles and I believe our seemly mundane every day existence is the miracle

[friskeysunset]

OutSTANDING work here. You took the whole thing apart and put it back together for me to understand that Einstein's limit is really about causality and the nitty-gritty of why all of my little fever-dreams for FTL communications are impossible using entanglement. In half an hour. Bravo.

My heart is broken, of course, but you let me down as easily as anyone could have, and your closing remarks about facing reality as it is was right on target. Thanks.

[EricMalette]

I read this terrific sci-fi series called The Gap, by Stephen R. Donaldson. I was in my teens, so I had no notion of the idea of entanglement or quantum. In the books the aliens called the Amnion, had this crystalline device that allowed them to communicate not only faster than light but essentially instantaneously. The shock of the human characters when discovering this was truly chilling. They could place their ships where they needed to be without dispatching a gap courier drone to cross the void. Truly hideous.

[dominicmillerca]

After listening to a lecture by Alain Aspect two weeks ago, I've decided to attack the subject with the book "Introduction to Quantum Mechanics" by David J Griffiths and Darrell F. Schroeter, it's pure food for the brain. Your video couldn't be more on target with the topic. As usual, very interesting and clear with a great sound quality and beautiful video editing. 👍

[spacescienceguy]

Cool to see 'ansible' mentioned, as it's the first thing that came to mind when I saw this video title! I came across the concept of an ansible (device for FTL communication) in the Ender's Game series, but it was an homage to Le Guin's work.

[doggonemess]

I am really proud of thinking up the "tachyonic telephone" when I was younger. I only discovered that someone had dreamed it up almost 80 years before I did, but I love the theory. Using tachyons, which may travel backwards through time, you can send a message to a far away receiver. They would get the signal in the past, relative to the distance light takes to travel that distance. I can form the idea in my head, but can't explain it. If you look up the term, someone else can do a better job than me.

[TheInterestingInformer]

I always click on these videos knowing the answer is gonna be no, but always hoping I’m wrong

[jcevans]

I'm no rocket scientist, I can barely wrap my mind around what you're saying, but I am a science nut, I love all things space related. I love your presentation, for lack of a better description I find this video soothing? Its like Relaxing and learning at the same time. Sorry if I'm weird.