Sean Carroll

But, you know, if you ask, well, are neutrinos matter by this definition?

You know, neutrinos have mass,

but their mass is very low, so they move relatively fast, right?

Do they move slow enough to count as matter?

And the answer is, in the current universe, neutrinos are matter to cosmologists, because they're moving substantially slower than the speed of light.

But in the early universe, neutrinos were not matter.

They were radiation because they were moving close to the speed of light.

And that's just one definition of the word matter.

But the point is, you know, we invent words in natural language long before we start putting them to work.

scientific rigorous contexts and therefore we overload the individual words.

So as long as the subset of people to whom you're talking knows what you're talking about, it's fine.

The place you can go wrong is when

experts start using words in their localized expert way of talking when they're talking to broader audiences who are not experts, even if they're experts in something else rather than the general public, then it can get very, very confusing.

And I think that it's just a tiny aspect of the broader issue that it's sometimes hard to talk to non-expert audiences.

And the reason why is because

When we're trained to be experts, we start thinking in a certain way, start talking in a certain way, and it becomes almost impossible to remember what it was like to not think and talk that way.

And so it's a real skill to be able to talk to audiences who don't know the jargon, even if the jargon is sort of non-threatening, like the word matter.

Matter is a great example of a thing, you know, unlike, let's say, Hilbert space.

When you say Hilbert space, everyone knows you're talking jargon, right?

So they're like, what does that mean?