光年级间距下费曼双缝实验的干涉现象及量子特性问询

Great questions—they get at some core ideas in wave physics and quantum mechanics that trip up a lot of people, so let's unpack them one by one.

1. Will an interference pattern form if the light source is light-years away from the double slits? #

The short answer is: yes, under the right conditions—distance alone doesn't kill interference. Here's why:

• Interference depends entirely on the coherence of the light reaching the slits, not how far it traveled. Coherence means the light waves have a consistent phase relationship across space and time.
• If your distant source is coherent (like a well-stabilized laser, or even a small, distant star that acts like a point source), the light hitting the two slits will still have correlated phases. As long as the path difference between the two slits is smaller than the light's coherence length, you'll see a clear interference pattern.
• Real-world caveats: Interstellar dust, gas, or gravitational lensing could scatter the light and degrade its coherence. A large distant star might also have enough angular size that different parts of the source emit uncorrelated light, which would wash out the pattern. But in an ideal scenario (perfectly coherent source, no intervening disturbances), light-years of distance won't stop interference.

2. Single electrons in a light-year-spaced double slit experiment—do they "sense" blocked slits faster than light? #

This is a super common misconception, so let's set the record straight:

• First, a single electron doesn't "simultaneously pass through both slits" in the classical, intuitive sense. What's actually happening is that the electron's quantum wavefunction spreads out, and components of that wavefunction interact with both slits. Over many trials (sending one electron at a time), these wavefunction components interfere with each other to create the classic pattern on the detector.
• If you block one slit, the wavefunction only has one path to follow—so no interference pattern forms. This isn't because the electron "knows" the slit is blocked via some faster-than-light signal. It's because the blocked slit changes the boundary conditions for the wavefunction: it can't propagate through that slit anymore. The change in the pattern only affects electrons that pass through after the blocked slit's influence has propagated to the slits (at or below the speed of light).
• This isn't quantum entanglement, either—entanglement involves correlated states between multiple particles. This is a single particle's wavefunction exhibiting wave-like behavior. Most importantly: you can't use this setup to send information faster than light. The interference pattern only emerges after accumulating many electrons, and altering the slits would only affect future electrons, not ones already in transit.

内容的提问来源于stack exchange，提问作者user6760