Most papers that are published on arXiv or in paper journals carry a line under the author’s name telling you how to contact them. Generally, this is the address of the institution, typically a university, where the author did the work, and this can include their email address. Of course, being retired, I had no such institution, and I decided against adding my private email address when I submitted my paper on the mathematical structure of the multiverse. However, in order to submit a paper to arXiv, you have to register, and this does include telling them separately your email address.
One benefit of registering is that you get to see other authors’ private email addresses when you login. So, when my paper on the mathematical structure of the multiverse was published, people who had already registered could contact me through this facility.
Sure enough, I duly received emails about the paper. What I didn’t expect, though, was that the issue that exercised people the most was not the claim that our universe is part of an unimaginably vast mathematical structure – the Plexus – topped by a Gödelian transfinity, but that we live in a block universe in the sense that future events are “already” embedded in its spacetime fabric.
I always viewed the block universe as a necessary condition for the Plexus, so that the Plexus would be the more difficult of the two ideas to swallow. However, maybe the block universe is seen as an easier target. As one respondent put it: “…many physicists and philosophers would argue … that only events in the past light-cone of known events are determined, and thus relativity does not require the block universe.”
In other words, if the sun extinguishes …now!… it is nevertheless not part of your past until eight minutes have elapsed, during which time, anything might or might not happen! It seemed to me that, while the respondent’s claim about the past light-cone containing determined events is surely true, nonetheless, for an observer very close to the sun, the extinction would be part of their past almost immediately. Since that observer’s past cannot be changed, there is an inevitability to the extinction event that will be manifest to you in eight minutes. It is this inevitability that constitutes the embeddedness of events in the fabric of spacetime.
Equally, what grounds did this respondent have for distinguishing between the past light-cone and the future light-cone? Why can events be embedded in the past light-cone but not in the future light-cone?
Still, I can see the difficulty. We are used to thinking that, while we cannot change anything in our past, the future is an open book, there to be modified according to our will. I have decided to add pages about free will to this website much later on, but in the meantime, I was prompted by repsonses such as the one above to adapt the Block Universe page into a second paper for arXiv.
I have added this new paper to the Plexus page. It differs slightly from the Block Universe discussion in that it is Alice, and not Bob, who transmits the continually repeating signals, but that is a minor detail. Another difference is that I chose to use separate planets – Earth and Mars – instead of Alice and Bob both being on or close to Earth, for the experiment. This change means that events in Bob’s past can be even further ahead in Alice’s future.
It may be that the block universe – where your future is already indelibly written – is such an alien concept that, once you do get it, the idea of the Plexus itself is going to be a walk in the park!