And before the big bang?

How did we get here? What was here "before"?  No one knows. We know some things, however.

We can observe is that the universe is expanding, and we can determine that 13.73 billion years ago, all of the "stuff" outside of the Earth that we can now observe or infer was concentrated.

What about 50 billion years ago? No one knows.

PAUL DAVIES, a theoretical physicist and professor of natural philosophy, has this to say in his interesting article, "What happened before the big bang?"

... there is very good evidence that the universe did come into existence in a big bang, about fifteen billion years ago.

The effects of that primeval explosion are clearly detectable today-in the fact that the universe is still expanding, and is filled with an afterglow of radiant heat.

So we are faced with the problem of what happened beforehand to trigger the big bang. Journalists love to taunt scientists with this question when they complain about the money being spent on science. Actually, the answer (in my opinion) was spotted a long time ago, by one Augustine of Hippo, a Christian saint who lived in the fifth century. In those days before science, cosmology was a branch of theology, and the taunt came not from journalists, but from pagans: "What was God doing before he made the universe?" they asked. "Busy creating Hell for the likes of you!" was the standard reply.

But Augustine was more subtle. The world, he claimed, was made "not in time, but simultaneously with time." In other words, the origin of the universe-what we now call the big bang-was not simply the sudden appearance of matter in an eternally preexisting void, but the coming into being of time itself. Time began with the cosmic origin. There was no "before," no endless ocean of time for a god, or a physical process, to wear itself out in infinite preparation.

Remarkably, modern science has arrived at more or less the same conclusion as Augustine, based on what we now know about the nature of space, time, and gravitation. It was Albert Einstein who taught us that time and space are not merely an immutable arena in which the great cosmic drama is acted out, but are part of the cast-part of the physical universe. As physical entities, time and space can change- suffer distortions-as a result of gravitational processes. Gravitational theory predicts that under the extreme conditions that prevailed in the early universe, space and time may have been so distorted that there existed a boundary, or "singularity," at which the distortion of space-time was infinite, and therefore through which space and time cannot have continued. Thus, physics predicts that time was indeed bounded in the past as Augustine claimed. It did not stretch back for all eternity.

If the big bang was the beginning of time itself, then any discussion about what happened before the big bang, or what caused it-in the usual sense of physical causation-is simply meaningless. Unfortunately, many children, and adults, too, regard this answer as disingenuous. There must be more to it than that, they object.

Indeed there is. After all, why should time suddenly "switch on"? What explanation can be given for such a singular event? Until recently, it seemed that any explanation of the initial "singularity" that marked the origin of time would have to lie beyond the scope of science. However, it all depends on what is meant by "explanation." As I remarked, all children have a good idea of the notion of cause and effect, and usually an explanation of an event entails finding something that caused it. It turns out, however, that there are physical events which do not have well-defined causes in the manner of the everyday world. These events belong to a weird branch of scientific inquiry called quantum physics.

Mostly, quantum events occur at the atomic level; we don't experience them in daily life. On the scale of atoms and molecules, the usual commonsense rules of cause and effect are suspended. The rule of law is replaced by a sort of anarchy or chaos, and things happen spontaneously-for no particular reason. Particles of matter may simply pop into existence without warning, and then equally abruptly disappear again. Or a particle in one place may suddenly materialize in another place, or reverse its direction of motion. Again, these are real effects occurring on an atomic scale, and they can be demonstrated experimentally.

A typical quantum process is the decay of a radioactive nucleus. If you ask why a given nucleus decayed at one particular moment rather than some other, there is no answer. The event "just happened" at that moment, that's all. You cannot predict these occurrences. All you can do is give the probability-there is a fifty-fifty chance that a given nucleus will decay in, say, one hour. This uncertainty is not simply a result of our ignorance of all the little forces and influences that try to make the nucleus decay; it is inherent in nature itself, a basic part of quantum reality.

The lesson of quantum physics is this: Something that "just happens" need not actually violate the laws of physics. The abrupt and uncaused appearance of something can occur within the scope of scientific law, once quantum laws have been taken into account. Nature apparently has the capacity for genuine spontaneity.

In other words, time was created with the big bang, and before that, some strange quantum universe existed  without time. This idea matches observations we have made in this Time-Universe such as: At the speed of light, time does not exist. And sub atomic particles move instantly from one place to another. And spooky action at a distance of particles that are joined (entangled).

Evidence for the age of the universe:

The earliest and most direct kinds of observational evidence are the Hubble-type expansion seen in the redshifts of galaxies, the detailed measurements of the cosmic microwave background, and the abundance of light elements (see Big Bang nucleosynthesis). These are sometimes called the three pillars of the big bang theory. Many other lines of evidence now support the picture, notably various properties of the large-scale structure of the cosmos^[38] which are predicted to occur due to gravitational growth of structure in the standard Big Bang theory.  - wiki

If the Universe is only 13.73 billion years old, it seems still possible that some billion-year-old advanced intelligent alien civilizations exist out there. If we last long enough, we may be lucky enough to meet them and work on the bigger problem the entire universe faces: running out of energy.

After all the black holes have evaporated, (and after all the ordinary matter made of protons has disintegrated, if protons are unstable), the universe will be nearly empty. Photons, neutrinos, electrons and positrons will fly from place to place, hardly ever encountering each other. It will be cold, and dark, and there is no known process which will ever change things. - rit.edu

In a googol years (10 to the power of 100) which is "ten billion, billion, billion, billion, billion, billion, billion, billion, billion, billion, billion" years, the entire universe will be dead.

So. There it is. The universe, birth to death. No observable parents. No children left to bury it.

Can we have your liver then?