M,
I do speculate.  Probably everyone does. Quantum physics and cosmology are both tough areas, though. As humans, we find it hard to imagine that things might not have a beginning or end; like time and space. Or that things can work the way they tell us they do at the quantum physical level. So, I find that my mental machinery is already ‘challenged’ to try to imagine what they are telling me, much less to really grasp it and then imagine on further.
The ultimate question of where did the universe come from assumes a beginning. The idea that the universe will expand forever, suggests the question of what’s beyond the area it is expanding into. If you talk to scientists, some will tell you that it is the questions themselves that are wrong.
I used to try to understand how space/time could curve back on itself as Einstein suggested. That if you went long enough in one direction, you’d end up back in the same place again.  I never got it until someone pointed out the Mobius Strip as a representation of the idea and that being on the surface of a sphere is another. In both cases, you can start from a place and go in a direction and arrive back in the same place. With three-dimensional space, it is harder for our brains to wrap themselves around the same idea but, apparently, it is true.  So, there may not be a ‘beyond’ beyond what we see as strange as it might seem. I’ve read several laymen’s books on Einstein’s theory of Relativity and I still find them tough going.
I guess I’m seeing, as I’m writing, that in these areas I’m not speculating so much as trying to grasp what there already is to know.
The idea of the Big Bang and of what they call The Expansion bugs me.  It doesn’t feel right but that’s about all I can say about it.
And what about quantum physics?  They tell us that as you get smaller and smaller, you finally come to things the size of the Planck limit.  They say that there is nothing smaller. Well, I find that bizarre just like I find the idea that there’s nothing bigger than the universe or no beginning of time. But, perhaps that’s just because I inhabit an evolved mammalian brain which has no way to wrap itself around such ideas.
And Schrodering’s Cat is a situation that endless numbers of folks have thought about and gone away baffled and yet quantum physics tells us it is so.  Too weird.
So, where do I like to speculate? I’m fascinated by the mind and consciousness and what perception really is. What is awareness and self-awareness and how does the mind ‘model’ the reality around us?  How accurate or inaccurate are our perceptions?  The very tool (the mind) we use to ponder these things has inherent in it distortions and shortfalls that interfere with our ability to see through to the answers clearly.  I think a lot of this interest arose from having meditated for many years and spent a lot of time in inner spaces.
One of the reasons I enjoyed altered states of consciousness years ago was because they gave me an alternative to the normal state. And it is a truism that you cannot see where you are until you’ve seen it from some alternate place.  The more ‘elses’ you’ve visited, the more perspectives you can get on what is transitory and what is fixed among the different places.
Meditation allows you time to experiment with awareness without words, of being without time, of forming intentions and holding them as feelings and not words. Of identifying with the nervous system that is centered in your abdomen rather than the one in your head. Of separating your awareness from the stream of chatter that is ever arising from the mind’s language center. Of realizing as a direct knowing what creativity is and then coming back into normal consciousness and not being able to say it.
I like to speculate about history and where mankind is going and how this same drama might have played itself out on other planets where intelligent life evolved long ago and what might have become of those creatures if they managed to pass through their technological adolescence without destroying themselves.
I like to aggressively find and separate myself from my unconscious belief systems and replace them with things that I’ve had a good look at and have consciously decided are worth incorporating so that who and what I am is more and more a matter of conscious intentional choice rather than being composed of the flotsam and jetsam that happened to wash through my life during my formative years. And this connects back into a circle with the stuff I said earlier about trying to understand the foibles and limitations of the human mind. I highly recommend a book called “A Mind of it Own” by Cornelia Fine in this regard.
I find a lot of this to be hard going.  On every side, the temptation to get sucked into some bogus belief system is there. Hence, why I cleave so tightly to what science reveals. Hence why I constantly am taking time to stand away from my own beliefs and challenge them and look at alternatives so that I don’t get sucked into the trap of identifying with them and associated them with my ego and thus ending up defending them – right or wrong.
The ego is a big obstacle to clarity.  Cognitive dissonance is a big obstacle. Assumptions are a problem. The very way the mind works is a problem. And yet, someplace behind all of these shifting sands of illusion and misperception, is the bedrock reality we find ourselves within – even though each of us will give a different description of it.
I could go on for while like this.
Dennis