“Well, I have to somehow propagate signals faster than the speed of light. As soon as I do that, I automatically create the possibility of causal loops. Now, in

“Well, I have to somehow propagate signals faster than the speed of light. As soon as I do that, I automatically create the possibility of causal loops. Now, in a causal loop, A sends a signal to B— And it's all in the back of Bohm's textbook on special relativity. He has a very nice appendix in there where he describes all of this. But A sends a signal to B, B to C, C to D, D sends a signal back to A. And all of the observers are moving relative to each other, and I think that at least two of the four transmissions have to be super-luminal. And then just applying standard special relativity, A gets the answer from D before he sends the signal to B. So he's reversed the time order of these events. So he doesn't like the answer he gets from D, so he doesn't send a signal to A. So it doesn't arrive at B, so it doesn't arrive at D. So he didn't get it, so therefore he can't dislike it, so he does send it. So what does this say. Well, it says, the naive question is, "Well, does he or doesn't he send the signal." He can make the decision, "I will send the signal if I don't receive a signal from D," since that occurs in the other order. So, yes, he does, and no, he doesn't. And naively, I want to say, "Well, this is clearly absurd and impossible. It cannot happen, therefore one of our assumptions must be wrong. The only new assumption was that we could propagate super-luminal signals, therefore that must be wrong." That's the standard logic. Now, let's look at this for a second. What do we have. We have yes, he did, and no, he didn't simultaneously true. History is multi-valued! Where else did we encounter a very similar dilemma. The particle could go through the first slit, or the particle could go through the second slit, but the two are mutually exclusive, but both do occur. Well, let's wake up and smell the physics for a second. Where did we get these. We got one from quantum mechanics. That was the fact that history could have gone both ways, and in fact, must have gone both ways. The other we got from special relativity, which we got without knowing a lick about quantum mechanics. These are very different sources of exactly the same dilemma.“