Lightsaber blades, as explained in countless Star Wars material, are not beams of light. They are super-heated plasma encased in a magnetic field. The reason they repel each other is because of how magnets and magnetism works (same magnetic field? repell one another; opposite magnetic field? attract one another). This explains why it seems like such a struggle for jedi/sith to lock sabers, because they are literally fighting against the forces of magnetism. It also explains why in the prequels, their blades would only clash momentarily... because they were moving with the momentum of the blades repelling each other. Because lightsaber blades are super-heated plasma, it also explains why they can burn and cut through just about anything.

TL;DR: Not beams of light. plasma encased in magnetic fields.

Two things had to have happened here.

1. Tyson had no literary (EU or canon) research done into the subject of lightsabers. This is pretty bad and makes him look less like a scientist.

or

2. Tyson had the research done and ignored it all because he wanted to explore the concept of the probabilities of photons bouncing off each other and wanted to make it seem cool by tying it in to an awesome technological concept from a famous sci-fi property.

I think option 2 is worse...

Option 2 is definitely worse.

I don't want to mix science with my Star Wars (which sems like trying to put tomatoes in fruit salad) but if the plasma beams magnetic fields are able to interact with one another, they'd likely interact with other things as well. Wouldn't they be sticking to ferric metal surfaces they come in contact with? They don't really seem to, as they've been described. They've been explained as slicing through most metal things like a hot knife through butter.

I'm ok with the answer being, "Yeah, but it's Star Wars." That was a perfectly acceptable answer for why Qui Gon didn't burn off his hands when he sunk his lightsaber hilt deep in those blast doors on the Trade Federation's ship. I just want to know if that's how it would work if, say, I built my own lightsaber.

Not that I have. At least not that you know of!

Oh, I agree, mixing physics & science with Star Wars is mostly pointless. I was only responding with the in-universe explanation for what lightsabers are, in response to the idea brought forth by the celebrity scientists, that they are supposed to be lasers. In real life, we have plasma and we have magnetic fields. The trick is getting them to work in the way they do in Star Wars.

I don't want to mix science with my Star Wars (which sems like trying to put tomatoes in fruit salad) but if the plasma beams magnetic fields are able to interact with one another, they'd likely interact with other things as well. Wouldn't they be sticking to ferric metal surfaces they come in contact with? They don't really seem to, as they've been described. They've been explained as slicing through most metal things like a hot knife through butter.

I'm ok with the answer being, "Yeah, but it's Star Wars." That was a perfectly acceptable answer for why Qui Gon didn't burn off his hands when he sunk his lightsaber hilt deep in those blast doors on the Trade Federation's ship. I just want to know if that's how it would work if, say, I built my own lightsaber.

Not that I have. At least not that you know of!

I agree. Personally, I'm content with the "it's Star Wars" answer to almost any scientific and technical question and/or inconsistency. I like my space opera to be more Edgar Rice Burroughs than anything else, so YMMV.

I don't want to mix science with my Star Wars (which sems like trying to put tomatoes in fruit salad) but if the plasma beams magnetic fields are able to interact with one another, they'd likely interact with other things as well. Wouldn't they be sticking to ferric metal surfaces they come in contact with? They don't really seem to, as they've been described. They've been explained as slicing through most metal things like a hot knife through butter.

I'm ok with the answer being, "Yeah, but it's Star Wars." That was a perfectly acceptable answer for why Qui Gon didn't burn off his hands when he sunk his lightsaber hilt deep in those blast doors on the Trade Federation's ship. I just want to know if that's how it would work if, say, I built my own lightsaber.

Not that I have. At least not that you know of!

You might get weird effects like

I don't want to mix science with my Star Wars (which sems like trying to put tomatoes in fruit salad) but if the plasma beams magnetic fields are able to interact with one another, they'd likely interact with other things as well. Wouldn't they be sticking to ferric metal surfaces they come in contact with? They don't really seem to, as they've been described. They've been explained as slicing through most metal things like a hot knife through butter.

I'm ok with the answer being, "Yeah, but it's Star Wars." That was a perfectly acceptable answer for why Qui Gon didn't burn off his hands when he sunk his lightsaber hilt deep in those blast doors on the Trade Federation's ship. I just want to know if that's how it would work if, say, I built my own lightsaber.

Not that I have. At least not that you know of!

You might get weird effects like

. Basically, when you expose a lot of compounds (of which water is one) to a magnetic field, they produce an opposite field in response. For very high applied fields (like the sort of field you'd need to contain your plasma without any leaking out) the diamagnetic field can be so strong the force between the two is a measurable one, hence the levitating frog. So small birds could happily perch on the blade of your lightsaber.

I like this thread

Put one of those religion-inducing god helmets on the frog as well, to truly screw with it.