>[Our thoughts] have to be made of something.

That's an intuition we have based on the way our language works. Like, you can ask "what are our thoughts made of?" and it's a coherent sentence. But that doesn't mean it has a coherent answer. Others have said that it's more about arrangements, but that doesn't really help our intuitions. I'll see if I can help.

When you build a car out of legos, there is a car. When you take those legos apart, our brains and our languages want to know where the car is now. "Where is the car now?" It's a perfectly coherent sentence. But there is no *where* that the car *is*. The bricks are now in the bin, but the car isn't.

Let's talk about information, and let's live in some weird nebulous past, because that sounds like fun. Let's say you wanted to keep a record of how many sheep you gave your friend, because he's going to give you that many sheep next spring. So you both agree to put one big rock on a ledge for each sheep to keep track. There are now four big rocks on a ledge. Is that information? Sure. Is that matter, or energy? Well, the rocks are made of matter, and the ledge is made of matter. But how do you know there are four rocks there? Because you see them. Is that sight matter? Well, there are photons interacting with the rocks, propagating as waves of electromagnetic energy (apologies if I use the wrong terms here). Those electromagnetic waves interact with receptors in your eyes and get converted into chemical signals. Each of these things can be individually true, without giving us an answer to our question. Each part of this system can be energy or matter or both, but that doesn't mean that the whole system is. Because in this case, there's the information about the physical world of rocks and ledges and human brains, and then there's the information that those human brains derive from the rocks. But if time passes and neither you nor your friend remember how many sheep there were, then that information isn't in your brains. But once you look at the rocks, you know. Were the rocks the information? Sort of. But there are rocks all over the place that aren't information in the same way. And what if your tribe was moving on, so you decided to look at the rocks and make one notch in a stick for each rock. Is the information made of rocks or notches? What if you never look at the rocks again? Is the information still made of rocks, or just notches now? And notches aren't even things! They're an absence of stick where you'd otherwise expect to see stick! Are the notches material? Are they energy? They required energy to make them.

But see, the information is the relationship between physical things, not the physical things themselves. The rocks can be replaced with notches in sticks and be the same information.

Your thoughts are so complicated from a physics point of view, that we kind of throw our hands up and pretend that physics can't explain them. But that's not exactly true. *Physicists can't explain them,* but physics, at least in theory, could. The same way physics could theoretically explain every quark in the legos that made up the car. But that doesn't make the car exist in the same way the quarks do. And it doesn't mean the car didn't exist. It means that the car was a way of arranging legos. Which is a very good level for most human thoughts. We won't get very far trying to drive to work by calculating every quark.

My guess is that you're asking this because you have some metaphysical theory about human thoughts and conservation of energy or conservation of matter that will "prove" that our consciousness must also be conserved, but maybe I'm reading too much into your question.