# Knowledge of Quantum Hidden Variables Enables Backwards-In-Time Signaling
## 5 Causal Relations between Past and Future Events
This means that complex meaningful information (such as a Renaissance painting or a physics textbook) does not appear instantaneously from a random fluctuation, but it is the result of a lengthy evolutionary process or computation. For example, a Neolithic caveman could not have had the knowledge or the technique to paint [PERSON]'s Mona Lisa painting, and [PERSON] could not have had the knowledge to write a quantum mechanics textbook. This implies that by tying the transmitted bit to the result of a long evolutionary process, one is guaranteed that the value of the bit cannot have been already known in the past. For example, we could tie the value of \(b\) to some information that no one knows today, such as \"will Apple stock shares increase in value in ten years?\". This guarantees that indeed the bit was transmitted, and not known beforehand. Communication with the past together with the evolutionary principle lead to a chronology paradox [32]: suppose that [PERSON] sends to [PERSON] a picture of his painting and he painted it by copying her picture, then the painting would be generated spontaneously since [PERSON] obtained it from [PERSON] and [PERSON] from [PERSON]. 3. Relativistic causality (strictly enforcing non-superluminal communication of at least one event). A completely independent way of ensuring that \(b\) is sent to the past is to assume relativity and causality (as defined above) and tie the value of \(b\) to the unknown value of some degree of freedom that is spacelike separated from the observer at step 2 of the above protocol, but is accessible at step 3 of the protocol when one must \"choose\" the value of \(b\). For example: \"has the star Betelgeuse turned into a supernova?\" (Betelgeuse, in Orion, is a supernova candidate [33]). The supernova event is spacelike separated from step 2 and hence inaccessible if relativity plus causality is assumed, but it will become accessible at step 3, when it enters in step 3's past lightcone. A caveat is in order here. As discussed above, relativity + causality is incompatible with superluminal communication, but the knowledge of hidden variables immediately implies superluminal communication. Therefore, one can assume relativity + causality for the event that causes the value of \(b\) (e.g., the supernova explosion) _only_ if one is sure that the event in question is not communicated superluminally through some quantum hidden variables. D. Ontic randomness for some hidden variable. This entails that, at least in some cases, the outcomes of quantum measurements are intrinsically random. This is what the Copenhagen interpretation of quantum mechanics suggests, but an interpretation that uses hidden variables could say that randomness only arises because of lack of knowledge of the hidden variables. Indeed, hidden variables are based on the idea that a definite, pre-determined value existed prior to the measurement. Therefore, to be really intrinsically random, the hidden variables themselves must possess (at least in some cases) an ontic intrinsic randomness. Under this hypothesis, [PERSON] may perform a \(\sigma_{z}\) measurement of a qubit in an eigenstate of \(\sigma_{x}\) using an ancillary qubit whose hidden value is not predetermined. She then sends back the outcome as the value of \(b\), which could not have been determined in the far past under this hypothesis. Any of the above four hypotheses can be employed to conclude that in the above protocol the communication proceeds from the future to the past and not vice versa.