They do "reflect top to bottom".

Hold a written word in front of your eyes to read it.

Now flip it to the mirror to read the reflection:

Did you flip it horizontally? Then it reflected left-to-right.

Did you flip it vertically? Then it reflected top-to-bottom.

I think "reflect top to bottom" is intended to mean "swap top and button". A mirror reflects left, right, top and bottom perfectly. It's front and back that it swaps.

Someone saying that a mirror swaps left and right is comparing it to a photograph, and only because we, as bipedal creatures, really prefer to orient images of other humans with heads up.

Someone saying that a mirror is swapped left and right is because they rotated themselves 180 degrees about the vertical axis to face the vertically aligned mirror. If they used a horizontal axis instead, they would have swapped top and bottom. And if the mirror is horizontally mounted on the floor, anything goes. You'd probably say it swaps up and down, which is front and back from the mirror's point of view.

> It's front and back that it swaps.

This sub-thread is becoming unfairly more interesting than the main conversation at this point.

You know, I never thought about that.

This was my small "mind expansion moment" for today. Thanks!

So he is not the primary?

Call him Bob.

Nomenclature is just a convention of convenience and can be ever so judgemental.

Particle / anti-Particle ... way to lead the jury, hey?

What we do know is that when Bob walks up to a mirror he sees adastra22.

The glass is likely there to stop them touching and spawning a new universe.

Notice how in your own example, the anti-particle is not the particle, and Bob is not adastra22.

I did notice that these things are labels and not objects.

Good point.

And it would revolutionize our current understanding of physics to find out that p = p̄