All we have to actually experience are the six sense doors, their object, and their associated consciousnesses.....with these tools it is impossible to either prove or disprove the existence of an external world.....the external world is therefore a conjecture or construel on our part.
I am with chownah on this.
Sights, sounds, smells, tastes and touch are received through the 5 sense organs. No matter how much we know about this cosmos, our solar system and earth including everything that exist on the surface of this planet comes under rupa (material world). Rupa pertains to the tangible, so it refers to material forms (the four great elements, and the form dependent on the four great elements).
Once these vast diversities of sense objects walk over the bridges of perception and enter your inner world (immaterial world), the 5 sense objects have no choice but to abandon their material forms and turn into non-material entity (energy): perception, mental formations and feelings. Sights, sounds, smells, tastes and tangible sensations carry exactly the same information and details but in different forms.
By seeing, smelling and or tasting one knows an orange. To one born blind, colors and shapes doesn't exist. To one born deaf music doesn't exist. Planes,space-craft, cars and cities do not exist naturally but are brought into existence by the mind. Gravity doesn't really exist either but are mental constructs.
You see yourself as the centre of the universe. Without your 5 senses, the material world does not exist. This is what happens in the jhanas during meditation when the material realm is abandoned. The various realms may well be mind states. When you are in any of those events, sleeping, unconscious, in a coma, all your senses(incl the 6th) cease to function. At that moment, your very own private universe disappears too although it very much exists for other people who are fully conscious.
Sights, sounds, smells, taste, touch, feelings, memories, thoughts and consciousness don't persist and are constantly arising and ceasing moment by moment. Each moment of arising potentially causing a new round of self identification (I see, hear ...feel, think and I am) unless the phenomena are seen as what they really are. The last fetter of conceit "I am" is identification with consciousness itself.
Views are relinquished by one who has gone beyond Vaccha, for it is seen as it really is;
this is the body, this is it's origin, this it's cessation,
these are feelings, this is their origin, this their cessation,
these are memories, this is their origin, this their cessation,
this is the will, this is it's origin, this it's cessation,
this are experiences, this is their origin, this their cessation.
I say one who has gone beyond has completely relinquished and abandoned
all views and theories, all agitation and worry, all fluctuation of opinion,
all 'this is my view', all 'this is my opinion', all egotism,
for he is passionless, selfless, detached, liberated, calm.
And what is right speech? Abstaining from lying, from divisive speech, from abusive speech, & from idle chatter: This is called right speech.