[himata4113]

Wasn't the entire conflict behind entanglement that it appeared to have the capability to violate this princible with the only two explanations being: quantum state travels faster than the speed of light or we're in a many-worlds universe where state propagates backwards which means the information was there from the very beginning?

[luma]

The key word here is "information". No known quantum effect results in information being transferred faster than the speed of light (which might be more correctly known these days as a the speed limit of information). Entanglement, even at great distance, does not violate this principle as that cannot be effectively used to transfer information.

[visha1v]

The historical debate around Bell's Theorem and Einstein's "spooky action" often leads to this exact confusion, but quantum mechanics has an ironclad mathematical guardrail against this: the No-Communication Theorem.

Entanglement cannot be used to transmit messages, amplify bandwidth, or achieve "infinite compression" for a few foundational reasons:

1) The Classical Bottleneck: In quantum teleportation, you aren't actually moving information through space faster than light. To reconstruct the state of a teleported qubit at the destination, the sender must transmit two classical bits of data over a standard, traditional channel (limited by the speed of light, c).

2) The Randomness Vector: Without those two classical bits, the receiver's particle looks like completely randomized entropy (a maximally mixed state). You could spin your entangled particle right now, and the person on Mars would see their particle change state instantly—but to them, it just looks like a random coin toss. They cannot know what you chose to measure or what your result was until your classical radio signal arrives to break the encryption.

3) Holevo's Bound: From an information theory perspective, Holevo's theorem proves you cannot extract more than one bit of classical information from a single qubit. While superdense coding lets you pre-share entanglement to send two classical bits using one physical qubit, it still requires physically moving that qubit through space at or below the speed of light.

Whether you favor Copenhagen, Many-Worlds, or Pilot Wave theory, the physical reality across all interpretations remains identical: local causality is never violated. Entanglement shows us that nature is non-local, but it completely forbids us from weaponizing that non-locality to send a signal faster than c.

[himata4113]

That's the bit I was thinking about the most: "pre-share entanglement to send two classical bits using one physical qubit" I did mention that we cannot achieve data transfer faster than the speed of light, but with the use of "teleportation" we can increase bandwidth that still holds true doesn't it?

But that does clarify quite a few things thanks!

[himata4113]

llms fall for this every single time lol.