It is not possible to reference anything outside the mind.
This means that anything you call real -- anything you CAN call real -- is a reference to mind. "Time," "space," "the REAL time," "the REAL space," "yeah but the REAL time outside my mind" etc. Also, actual time. Yes, that one. Omitting the quotation marks changes nothing.
This is hard to understand properly, but meditation can make it clear. Until then it can seem quite certain that you're referencing, and even experiencing, things other than mind.
Maybe even after all that meditation, nothing will have changed. Or maybe it will open up doors you've never dreamed of.
Why not find out?
"When you start to dream, the dream begins as a thought, like one you would have in the daytime. But you’re asleep, so the thought intensifies and becomes something like talk or gossip, and then the gossip intensifies or solidifies into images, and then you really think that you’re seeing people, seeing places, going places, and so on. And that is how it works with conventional appearances as well."
-- Thrangu Rinpoche