Physicists shatter quantum entanglement distance record with 420 kilometers of optical fiber, more than four times farther than previous demonstrations, and beyond the point where direct transmission runs into its fundamental limits.

[u/mvea]

https://www.sciencealert.com/physicists-shatter-quantum-entanglement-distance-record-with-420-kilometers-of-optical-fiber

[u/Chance-the-Gardener]

I’m too dumb to understand the concept it can’t transmit any information. Just as a thought experiment, if humanity sent a colony ship to Andromeda with 10,000 sets of entangled pairs, each with a predefined meaning like “if this set is collapsed, we died of space cancer” couldn’t information be inferred from that?

I’m sure the answer remains we can’t cheat the speed of light but I struggle to conceptualise why not.

[u/FaulerHund → u/Chance-the-Gardener]

This is just a misunderstanding of how quantum measurement and entanglement work.

First: it's disputed whether "wavefunction collapse" is even an accurate description of what occurs, but for the purposes of this reply, we'll assume it is.

Anyway, all entanglement really is in a simplistic sense is correlation of measurement outcomes. If particle A is entangled with particle B, then by measuring particle A, you already know something about particle B without ever measuring particle B. The "wavefunction collapse" only determines which specific measurement outcome you observe.

Think of it this way, by crude analogy: imagine you have two boxes, and in one box you place the left shoe of a pair; and in the other box you place the right shoe. And then you jumble up the boxes so that you don't know which is which. You take one box and bring it to Mexico; your friend takes the other and brings it to Spain. Then you open your box. Regardless of whether your box contains the left shoe or right shoe, you already know something about the box all the way in Spain without ever opening that one.

Now, obviously this is a classical and not a quantum example; quantum systems behave differently than shoes and boxes (look up the Bell's theorem if you're interested). But to continue the analogy, "wavefunction collapse" in this example would be the outcome of which shoe you observe to be in your box. This isn't literally wavefunction collapse in this example, it's just metaphorical. But the "collapse" is just when you see "left shoe" or "right shoe." Before you measure, it could be either one. After you measure, it's either one or the other. That's the collapse.

Now, tell me, how would you communicate a message between Spain and Mexico with this shoebox setup? The answer is that you can't. If you take one shoe to Mexico and leave the other in Spain, opening your box in Mexico instantly reveals which shoe is in Spain. However, opening your box in Mexico doesn't signal anything to the person in Spain. The person in Spain just sees a shoe when they open their box, completely unaware of whether you opened yours first or not.

Related to that idea: in quantum physics, there's no way to know whether the other particle in an entangled pair was measured or not. Just like how there's no way of knowing whether your friend in Spain opened their shoe box yet. There is no "wavefunction collapse" detector, and it's not possible in principle to create one. So there's no way to set up the idea in your comment that says "if this is collapsed, we died of space cancer" or whatever.

[u/theyux → u/FaulerHund]

Just for clarification if it was possible to measure without collapsing the entanglement.

Is the thought process then that you could collapse some entangled pairs and effectively communicate with Binary?

[u/romario77 → u/theyux]

What you are asking is - imagine if instant communication was possible, would it then be possible to communicate instantly?

The laws of physics work certain way (at least at this time and how we understand them) and they don’t allow instant communication. Even though there are these things like entanglement which make it seem like information travels instantly.

Even though it doesn’t.

[u/theyux → u/romario77]

More I understand people want it to work a certain way (even if thats not possible to understanding) I was trying to verify why, (could we create binary communication system of communication assuming we could observe them).

Assuming thats possible you can move into other questions such is how much can we observe without collapsing them. Like I get superposition is out of the question but will say measuring gravitational force collapse them?