Maybe.
Our senses through which we experience the world are demonstrably fallible. Whether through sleight of hand and deception, or incorrect models and assumptions, what we think we know as concrete is often murkier than it first appears. suggests Mathematics may be a suitable answer; however, upon close inspection even math's cracks begin to show. Godel shook the math world with his which proved any axiomatic system necessarily contains contradictions. It turns out Mathematics, which seems so definite and absolute, has just as shaky a foundation as the musings of philosophers.
Can anything be truly proven? Philosophers have toiled away at this question trying to find anything they could be absolutely sure of. Descartes famously postured, "I think therefore I am", but does thinking necessitate existing? Perhaps he didn't exist even though Descartes thought. Socrates on the other hand believed any true knowledge was out of reach saying, "The only true wisdom is in knowing you know nothing". He did seem to think knowledge was theoretically attainable, unlike some philosophical skeptics that followed him.
So perhaps matter exists outside of experience like naive realism asserts, or maybe you're just a being fed false stimulus. It's impossible to know for sure. This quote by Thomas Metzinger always sticks with me when discussing perception and it's bearing on reality. "Our conscious model of reality is a low-dimensional projection of the inconceivably richer physical reality surrounding and sustaining us. Our sensory organs are limited: They evolved for reasons of survival, not for depicting the enormous wealth and richness of reality in all its unfathomable depth."
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