QR3.8.4 Non-physical Detection

Using quantum waves, physicists can detect an object without interacting with it physically. In a purely physical world, this is impossible, but in our world it isn’t. Figure 3.22 shows the Mach-Zehnder device that lets experimenters detect objects on a path that light didn’t take.

This device splits light into two paths, to the two detectors, then splits it again to give four paths. The light shines onto a splitter that sends half the light down path 1 to detector 1, and half down path 2 to detector 2, where the mirrors make the paths cross. As expected, each detector fires half the time. Then a second splitter is added where the paths cross to split the light again, half to each detector. But now the result is that detector 1 fires but detector 2 stays silent. Quantum theory explains this as follows:

As photon waves evolve down the paths, each mirror or splitter turn delays its phase by half. Both paths to detector 1 have two turns, so they add up, but path 1 to detector 2 has three turns while path 2 has two, so they cancel out. Detector 2 then never fires because the waves from the two paths to it are out of phase, and so always cancel.

This setup then allows a very unusual result. If an object that detects any light is put on path 2, the previously silent detector 2 sometimes fires without the object detecting anything. This doesn’t happen if path 2 is clear, so this proves there is an object on path 2 without touching it. To recap, the results (Kwiat et al, 1995) are:

1. With two clear paths, only detector 1 fires.

2. If an object blocks path 2, detector 2 sometimes fires without light touching the object.

Quantum theory then explains this result (Audretsch, 2004), p29, as follows:

Again, light waves evolve down both paths, so they hit the object half the time, but the other half of the time, they go down path 1. However, if path 2 is blocked, the waves to detector 2 no longer cancel out, so it fires sometimes, even when the object on path 2 registers no light. This result only happens if there is an obstacle on path 2.

To illustrate how strange this is, let path 2 contain a bomb that even one photon can set off, but the experimenters don’t know this. Yet if they are lucky, sending a photon down the system will trigger detector 2, which proves the bomb is there, although no light touched it. This is a bad way to detect a bomb, as half the time it sets the bomb off, but they still detected the bomb without touching it!

Non-physical detection supports quantum theory but materialism can’t explain it at all. If only physical things exist, how can we register one without physical contact? How can a photon detect a bomb on a path that it didn’t take?

This result suggests that quantum theory is literally true, so light must be a processing wave that spreads instances down all four paths to the two detectors. Table 3.2 shows the four paths that light can take, with their result probability. As shown, half the time the bomb goes off, and sometimes detector 1 fires, but sometimes detector 2 fires without triggering the bomb. Non-physical detection is when an instance travels down path 1 to detector 2, avoiding the bomb, to trigger a physical event.

Non-physical detection is the ultimate proof that quantum waves exist, as materialism can’t explain it at all, but a processing model can. The evidence is clear, even though current physics can’t accept it. 

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