In this post, I address a question that pops up from time to time as a possible objection to the transactional picture. The scenario involves a very distant star that engages in a transaction with a person’s eye, so that they see the star as it existed billions of years ago. But suppose the star has long since ceased to exist, and that it sent out that photon long before this observer was born? How did the star “know” that the observer would be in the right place at the right time to engage in this transaction?
Actually, the star didn’t need to know, because it didn’t send out the photon “long before the person was born” in any absolute sense. There are two main issues overlooked in the construction of this little paradox:
(1) In view of relativity, distances and time lapses are only relative, as is the time order of spacelike-separated events.
(2) No transaction can be set up without the availability of an absorber, in the present, so that any photon transfer establishes the emission event in the past.
First, consider point (1), with reference to the diagram below. Assume the star and the person (call him Bob) are in the same inertial frame. The star’s timeline is on the left; event E is the emission, and event F is the star’s demise. Bob’s timeline is at location x. The story in which the star has ceased to exist before Bob comes along only holds relative to certain inertial frames, among them Bob’s rest frame. In fact, there is no invariant distance between the star and Bob, nor is there any invariant time of travel for the photon to get from the star to Bob. There is also no invariant time order of the events involving Bob’s birth (denoted by B) and the star’s emission event E, since these events are spacelike-separated. Consider a rocket ship traveling very fast from the star towards Bob. Its spatial axis (compressed to one dimension) is the slanted line intersecting point C. This means that point C is simultaneous with the star’s emission according to the rocket’s perspective. From the rocket’s perspective, Bob was born before the star emitted, even though from Bob’s perspective, he was born after the star emitted.
According to the rocket, the spatial distance from the star to Bob is x’, and the time it takes for the photon to reach Bob is t’. These are much smaller than the values x and t assigned by Bob. Thus, from the rocket’s perspective Bob is much closer to the star, and the time of the photon’s travel is correspondingly reduced. In addition, from the standpoint of the rocket, the star dies well after Bob becomes available as an absorber (well after C, as can be seen by drawing a line parallel to the x’ axis from F to Bob’s timeline).
The lesson here, courtesy of relativity, is that the ability of a source to engage with absorbers is not restricted by sequences of events or spatiotemporal displacements relative to any particular inertial frame, since those are not absolute conditions. In this case, we see that according to the rocket ship, there is nothing “out of order” about the star engaging in a transaction with Bob.
Regarding point (2): The advent of incipient transactions is governed by absorbers in the present, and the actualized transaction acts to extrude the new spacetime interval from the present into the past, as a new element of the “spacetime fabric” (think of a knitting process). In this sense, all transactions have a form of built-in retrocausation, but it’s limited to the establishment of new spacetime events (not any changes to already-actualized events). Emitters and absorbers negotiate in the present (which we can identify with “Quantumland,” the quantum substratum which is a precursor to spacetime) via offer waves (OW) and confirmations waves (CW). It’s only at the final stage of an actualized transaction that a “past event” is established— the actualized emission event. So generation of OW and CW, which act beyond spacetime in the quantum substratum, must be carefully distinguished from the actualized real photon that is a spacetime entity—the connection between actualized emission and absorption events—and is represented by a projection operator. Emitters and absorbers remain in the quantum substratum. The actualized events that make up spacetime are activities of emitters and absorbers; the latter never become part of the spacetime manifold. In this sense, they are “eternally present.”