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I hate that I understand all the layers of this one except the duality one.
Light (in fact everything) is a wave, with some traditional particle properties added in. It's relatively easy to wrap your head around the weirdness from that point of view. It's almost impossible to make sense of it from a "particle with wave properties" view.
It's also worth noting that it is not observation, but measurement that matters. All observation is measurement but not all measurements are observations.
Basically, to measure something, you need to hit it with something else. Using a particle analogy (since the wave version is FAR less intuitive), imagine a pool ball, rolling down a table. You can only detect balls hitting the cushions. To measure where it is, in between, you need to roll additional balls across the table. In traditional physics, these balls can be thrown as lightly as you like, as accurately as you like. Unfortunately, the wave nature of the system imposes lower limits on this. When you throw a ball, it changes the ball it hits. To gain information, you end up damaging or destroying the system you are measuring.
In quantum mechanical terms, the wave function is collapsed. In fact, it's combined with the new particles you used to measure things.
In the original post. When you're not looking, the wave of the photon passes through both spits, it then interferes with itself. Only when it reaches the detector is it collapsed (by interacting with the atoms of the detector). When you try and measure which slit it went through, you introduce a new wave. This changes the shape of the original, and makes it appear like a particle.
This is quite a fun way of making yourself think in terms of waves. https://www.andreinc.net/2024/02/06/the-sinusoidal-tetris
It’s almost impossible to make sense of it from a “particle with wave properties” view.
"I want to emphasize that light comes in this form-particles. It is very important to know that light behaves like particles, especially for those of you who have gone to school, where you were probably told something about light behaving like waves. I'm telling you the way it does behave- like particles."
Richard Feynman, "QED The Strange Theory of Light and Matter." Introduction, Page 15.
As you read deeper, it's more and more obvious. Light is neither. It's a quantum mechanical object that has no direct analog in classical physics.
Under some conditions, the wave properties are dominant. In others, the particle. In most quantum mechanical problems, both are present.
My main point is that you get log jammed if you try and add the wave properties to a particle concept. There's nothing it can properly connect to. However, a wave can look like a particle, if you set it up right, and squint hard enough. In graph form, it's normal distribution with standard deviation close to zero. Basically a spike, with some slight rounding. It's far from perfect, but it gives our limited brains an anchor to work from.
Light is neither
I would agree that light is neither but Feynman is very adamant that it's a particle and he describes all the properties of light using a particle only model. It's much simpler conceptually to keep everything as a particle than treating light as a wave that sometimes collapses to a particle.
In his book he used the Mayan numbering system as an analogy. You can do everything in math by counting one by one, it's only extremely cumbersome. In a similar way he saw waves as a mathematical method to make calculating particles easier in some situations. But underlying the fancy math, it's still counting one by one.
Feynman argues that you can calculate and observe everything as only particles but you can never observe waves and have to make waves instantly transform into particles if you treat them as waves.
I think this is the part I've always have had issue trying to understand, thanks for helping clarify with an example.
Light is a particle and a wave, maybe?
Most particles are, researchers have shown that even macro-molecular objects like buckyballs behave like a wave in the double slit experiment.
I get that part. With absolutely no disrespect or jokes to the person who asked why there was a duality to the meme, I was actually wondering if the question was another joke I wasn't understanding. (Many comment-based double entendres fly over my head, unfortunately.)
Still though, this whole area of science is confusing, especially when trying to understand EM radiation from antennas. You can shake some electrons in a metal wire and generate a wave (of photons?) that can cause the electrons in another wire to ocillate. (It's really weird when you think a little on that.)
I have heard the word "photon" being used in regards to EM recently, and that is confusing me a bit. It seems legit on the surface when thinking about how energy is transferred, but it also kinda doesn't. Would you happen to have any clarity on that?
I would suggest reading the book QED: The Strange Theory of Light and Matter by Richard Feynman. He won the Nobel Prize for his theory of how light and matter interact and it has been tested to more accuracy than even Einstein's Theory of Gravity.
The book is written for anyone to understand without any mathematics.
What makes his explanations so simple is he is adamant that photons are particles and explains everything as particles interacting.
So your question about EM becomes: an electron in a metal emits a photon, the photon travels until it hits another electron in a piece of metal, that electron's energy is measured and you received the signal.
Thanks for the details. I am to the point now that the concepts are clear enough that solid literature could fill in some blanks. (It's taken me about a year or so before I could actually begin to visualize wave/particle concepts. Not gonna lie: PBS Space Time and Sabine Hossenfelder videos helped a ton.)
Ok, cool. The issue was that I had previously visualized the EM wave as being more akin to how electrons flow through wires, but with more magic involved. Once I started to revisit many my core conceptual beliefs, there was a ton that didn't make sense. Basically, you just gave me some validation, thanks. (There aren't too many people in my life that are interested in the nuances of photons, believe it or not.)