Is everything about the world the 6 sense objects

The other answers mention sense-objects and sense-organs, and contact (and could also mention sense-consciousness) -- see also Ayatana (e.g. on Wikipedia), and the Sabba sutta ("The All").

Additionally:

• The question ("is nothing really out there") could also be understood as implying that you're asking about the doctrine of emptiness or sunyata -- see e.g. the answers to What is the purpose of the Mahayana 'emptiness' doctrine? -- if only because that's translated as describing whether things have "real" existence.

• I think that "names" are mind-made -- all words, like "horse" and "tree" and "Buddhism" and "John etc. etc.

• There are "formations" or sankharas, I think those might be categorised as mind-made too -- e.g. if you'd ever associate a place with a person, with a smell, with a feeling.

• I suppose that tendencies (anusaya and asava) might be called "mind-made" too -- see e.g. the answers to What is effluent?

• Perhaps I should mention "wisdom" too, I'm not sure whether that's categorised as part of "everything about the world", nor even whether it's entirely categorised as "mind-made" (I think the Buddha is sometimes described as having "discovered" or "rediscovered" the Dhamma rather than as "inventing" it)

In summary Buddhism does see the mind as important -- and as trainable, and see e.g. the first couple of verses of the dhammapada -- but at least in this realm the mind tends to be conscious of (or to "sense") forms, sense-objects.

Since 5 of the 6 sense objects are not mind-made, obviously the world is not mind-made.

The world as we know it is from our senses. If we have not sensed something it is not there in our world. Before the microscope, there was no notion of microbes. When the way to sense it came about this expanded the knowledge of the world. For any being what he knows is the world.

This does not mean the world is mind-made. Our model of the known world is in our mind conditioned by our sense experiences.

It is not said anywhere in the teachings of Buddha that the world is the 6 sense doors. What is said is that we encounter the world, we sense the world, we come in contact with the world, through the 6 sense doors. Furthermore, since we have 6 sense doors through which we come in contact with the world, we cannot say precisely what the world is. And we cannot say that there is no world, for there is contact happening and because of this contact, phenomenon is encountered. To make assetions about the world, given that our encounter with the world is through 6 sense doors will be insufficient. To assert that there is no world would be incorrect because we know thorugh 6 sense doors there is a world. To anyone who says everything is in the mind, pick up a stone and throw at them and then ask- "Was this in your mind as well?" (Please dont actually throw a stone at anyone, I am simply pararphrasing a very useful Zen story about the mind-only reality):P

In my understanding, the suttas tell us that everything that can be cognized, it is cognized through our six sense-doors. The senses work conjoined with sensory stimuli and consciousness of each sense door, which arises only after the impingement between a stimuli with the sense-organ; the interaction between this three conditions is called "contact".

If one were to posit that something can be known outside of what our six senses offer to the mind, that would be inconsistent with our capacity to know the world.

From the above, we cannot conclude that "everything is mind-made", but only that we feel and get "our" information through "our" senses. Now, if you want to know where does this sensory data come from, I would argue that such answer is out of reach, beyond our ability of knowledge. The very question of "how can we feel what lies beyond our feelings" becomes contradictory, as far as I can tell.

We can only be conscious about what we perceive; and we perceive only what we feel through our sense-doors (including the mind as the six sense-door).

In my opinion, this is why the Buddha equates the senses to "the world", because in practice we can only speak and reflect about what our senses are able to tell us. Anything beyond them might fall under the realm of speculation and fantasy.

Kind regards!