this post was submitted on 19 Feb 2026
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Have we ever actually proved it can exceed the speed of light in information travel? I swear I have seen stuff where its theorized the speed of light is also the speed of causality
Nope, the actual information must still be transported via a classical no quantum (and trusted) channel so that both ends can match their statistics and thus deduce the crytographic keys from the qunatum signals. And thats it what its all about: key exchange
thanks. I had forgotten about that I think mainly because I can't wrap my mind around how it works like if its intercepted and used then it will confirm that its void and produce a new one or such.
Yes. If you could transport information faster than the speed of light, it's easy to find examples that break causality, where an observer sees a message arrive before he sees it being sent.
I'd argue that that would be breaking our ability to properly interpret causality, not that causality itself breaks. Things still occur in the order they happen regardless of what order we see them happen from different perspectives.
No, not if the observer can see the message arrive first, and immediately send a faster than light signal to the sender that turns off their transmitter, preventing the sending of their message.
If they see the message arrive, it has already been sent (and received). Not seeing it get sent yet doesn't mean it hasn't happened yet. You're not accounting for the frame of reference translation involved. Some of the information in your example has travel time. None of that information starts traveling before the things that created that information occurred, though. Even if it might look like that from some perspectives. It won't look like that to others.
I'm sorry, but all of special relativity disagrees with you.
The only way that an observer can see a message arrive first before it was sent is if that message was also faster than light.
The propagation of the information that the signal was sent will be travelling before the information of the result starts to propagate. So even if the message is sent equal to light speed, there's only one point on the two expanding spheres where the cause and effect appear simultaneously. That message you're observing would have to move quicker than light for any observer to be overlapped by the effect bubble before the cause bubble reaches them. Both of those bubbles expand at the same rate.
How are you beating an ftl signal with your own ftl signal if you're relying on information that is moving at light speed to react to?