Dr. David Sinclair

How does the particle know that you've seen it?

There's a classic double-slit experiment, it's formally called, that was done, I believe, in the mid-20th century, maybe earlier.

If you fire two particles through two slits in a board, the board blocks the particles.

So you can fire electrons.

That's a good example.

Electrons, if you're observing them, will go straight through the slits and hit a backboard that detects it.

It can be film, it can be a detector, and it'll get two slits behind.

Makes sense, right?

That's our reality.

Two slits, particles go through.

If they hit the board, they don't go to the detector.

If they go through one slit, they'll land on the left.

If they go through the right slit, they'll land on the right.

Yeah.

If you don't look at it, the particles can behave differently.

differently they now behave not like a particle but by a wave as a wave and they interact with each other and they don't make two slits they make multiple lines on the detector most of them are in the middle so the heaviest bands are in the middle but they also form other bands the bands go on essentially infinite but most of it's you know within a range why because they're they're interfering with each other like waves but here's the thing

The mere act of looking at where they landed, if you are detecting that, you'll get two slits at the back, two lines.

If you're not detecting it, it'll form the pattern.

Yeah, well, you can observe it in real time and you can observe it retroactively, yeah.

It generally is not affected, but they've done experiments where there is some element seemingly of retroactive, but generally we're not going back in time.