What would I see if I looked through the double slits?

Question

The double slit experiments all talk about the photons hitting a screen. What if I replaced the screen with my own eyes? What would I see? For example, they talk of the quantum (photon) being a wave that collapses to a point only when it hits the screen. And the point is random. So would I just see a blur because the photons are randomly spread across my eye? Would it make a difference if I was wearing sunglasses? Would I be able to read through the double slits, or would it be blurry?

Answer 1

You have lots of questions here. We can answer them in general: The eye works just like a screen, so you would see exactly what occurs on the screen.

Now a major caveat here is that your eye is in a single location. If you just looked at the double slits you would see... double slits. The light coming through would be the correct brightness for wherever your eyes currently are. However, if you used a lens or mirror to focus the scene properly on your retina, you could image the same scene as we see on the screen. If you didn't set up such a lens/mirror, it would look the same as if you were looking into a projector. You see the color of whatever pixel your eye happens to be inside.

Also, there's not just one double slit experiments. There's at least a dozen. Some of them operate on single photons. You would not see anything interesting in these experiments. While the rods of the human eye are capable of detecting a single photon, you won't see anything interesting unless you integrate over hundreds and hundreds of photons. The human brain doesn't do that, so it would be hard to observe the interesting patterns.

Whether sunglasses matter or not depends on the experiment and the glasses. In general, sunglasses make things darker, so the effect of wearing them would... make things darker. However, some of the double slit experiment rely on polarization to demonstrate interesting behaviors. If you wore polarized glasses with those experiments, it would change the results.

In most experiments you cannot read through the double slits. They are intentionally made thin enough to diffract the laser light, so they would diffract any light coming from the page you tried to read from.

Edit: And as cleverly pointed out by Jon Custer, so not look at a laser beam unless you have done the calculations to prove it is safe. Many lasers can do permanent harm to your eye.