What is reality?

I have just finished reading This Way to the Universe, by Michael Dine, a theoretical physicist. It's essentially an overview of what physicists think they do and do not understand about the universe, trying to convey it to lay readers. I won't try to quantify how much of it I think I understand, but hardly anybody really understands it, including at the deepest level the theoretical physicists themselves.

But the details aren't really important to any but a few of us. The Big Picture is that scientific understanding has left all of our intuitions behind, along with all historical beliefs about the structure and meaning of reality. These old beliefs were mostly religious but also included metaphysical speculations that didn't need God, myth or scripture. But most people still depend on their intuitions about reality, and they needs metaphysical explanations that they can understand.

I'm willing to accept that 13.8 billion years ago the universe was compressed into a volume so small that spacetime as we know it could not exist. I'm willing to accept that before 10^-43 seconds after it started expanding, the four forces of nature - electromagnetism, the strong force, the weak force, and gravity -- were unified as a single force, whatever that exactly means. I accept that at about 10^-37 seconds, the universe underwent an enormous expansion, increasing in volume by a factor of 10^78 before the inflation stopped at 10^-32 seconds, then continued to expand more gradually. It wasn't until about 370,000 years that it cooled enough for protons and electrons to form hydrogen atoms, and light could travel freely through the universe. This event is the origin of the cosmic background radiation.

I can go on but again, the details are not the point. The standard model of particle physics and the quantum theory are equally bizarre. Actually quantum theory is even more bizarre. Physicists understand the history and the future fate of the universe through a combination of general relativity and quantum theory, but they haven't been able to put the two of them together into a single theory. But they do know that our universe is extremely improbable. All sorts of constants have to be just right for the universe to have been stable this long and to have produced stars and planets and people. 

This last problem has turned physicists into metaphysicians. They don't speculate the way the ancient Greeks did -- they have a whole lot more concrete information to go on. But they still don't know where everything came from, or why it came into existence at all, and in particular whether there may be other, even infinitely many universes, or what it even means to say that because the universe is, by definition, everything we can possibly observe.

What we definitely do know is that all religions are wrong, but we have nothing to replace them with when it comes to explanation of first causes. Buddha taught that it is pointless to speculate about first causes, but religions generally insist upon them. And most people can't free themselves from dependency on these explanations. I am content to live with the mystery, but it seems it is intolerable to the majority, and so we have preachers. If they can tell people what to believe about this, they can tell them what to believe about anything. And that is a problem.